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Springer Handbookof Medical Technology
Springer Handbook providesa concise compilation of approvedkey information on methods ofresearch, general principles, andfunctional relationships in physicsand engineering. The world’s lead-ing experts in the fields of physicsand engineering will be assigned byone or several renowned editors towrite the chapters comprising eachvolume. The content is selected bythese experts from Springer sources(books, journals, online content)and other systematic and approvedrecent publications of physical andtechnical information.
The volumes will be designed tobe useful as readable desk referencebook to give a fast and comprehen-sive overview and easy retrieval ofessential reliable key information,including tables, graphs, and bibli-ographies. References to extensivesources are provided.
123
HandbookSpringerof Medical Technology
Rüdiger Kramme, Klaus-Peter Hoffmann,Robert S. Pozos (Eds.)
With 1008 Figures and 139 Tables
EditorsRüdiger KrammeTitisee, Germany
Klaus-Peter HoffmannFraunhofer Institute for Biomedical EngineeringMedical Engineering and NeuroprostheticsSt. Ingbert, Germany
Robert S. PozosSan Diego State UniversityDepartment of BiologySan Diego, CA, USA
ISBN 978-3-540-74657-7 ISBN 978-3-540-74658-4DOI 10.1007/978-3-540-74658-4Springer Heidelberg Dordrecht London New York
Library of Congress Control Number: 2011933994
c© Springer-Verlag Berlin Heidelberg 2011This work is subject to copyright. All rights are reserved, whether the wholeor part of the material is concerned, specifically the rights of translation,reprinting, reuse of illustrations, recitation, broadcasting, reproduction onmicrofilm or in any other way, and storage in data banks. Duplication of thispublication or parts thereof is permitted only under the provisions of theGerman Copyright Law of September 9, 1965, in its current version, andpermission for use must always be obtained from Springer. Violations areliable to prosecution under the German Copyright Law.The use of general descriptive names, registered names, trademarks, etc. inthis publication does not imply, even in the absence of a specific statement,that such names are exempt from the relevant protective laws and regulationsand therefore free for general use.
Production and typesetting: le-tex publishing services GmbH, LeipzigSenior Manager Springer Handbook: Dr. W. Skolaut, HeidelbergTranslation of Chaps. 1, 3–7, 17, 28, 35, 47–51, 54, 58, 60 from German byGrace Hughes on behalf of Translearning GbR, MannheimTypography and layout: schreiberVIS, SeeheimIllustrations: le-tex publishing services GmbH, Leipzig, Hippmann GbR,SchwarzenbruckCover design: eStudio Calamar Steinen, BarcelonaCover production: WMXDesign GmbH, Heidelberg
Printed on acid free paper
Springer is part of Springer Science+Business Media (www.springer.com)
89/3180/YL 5 4 3 2 1 0
(eBook)
V
Preface
This Springer Handbook is an overview of the ex-panding and exciting field of medical technology inwhich the reader will find a modern presentation ofthe relevant aspects of research, design, manufactur-ing, and application of different medical devices. Thefollowing components: Basics, Functional DiagnosticsDevices, Monitoring, Medical Imaging, TherapeuticDevices, Rehabilitation, Medical Information Process-ing, Telemedicine, Equipment and Tools cover themajor aspects of this field.
The handbook was compiled to be an indispensableresource for professionals working directly or indirectlywith medical systems and appliances. Just as impor-tantly, it was organized for graduate and postgraduatestudents in hospital management, medical engineering,and medical physics.
Medical technology has a long and productive tra-dition of developing medical devices, and innovativeapproaches to solve critical problems in medicine, bi-ology, and environmental sciences. Hence, biomedicalengineering is a rapidly developing field, which exem-plifies multidisciplinary approaches such as biotechnol-ogy, microsystems technology and telematics. Biomed-ical engineers develop devices and systems whichultimately contribute to the identification, treatment,abatement and monitoring of diseases and to the com-pensation of disabilities. The use of modern diagnosticmethods enables the early and safe identification of nu-merous diseases and improving therapeutic outcomes.Using engineering methods to address medical prob-lems will foster additional breakthroughs in clinicaltreatment and management.
The transfer of ideas from basic research and pro-totyping to the final medical product, including the
methodological questions of application requires con-tinued cooperation between teams. The result of theinteraction of basic and clinical medical sciences, in-formation technology, engineering, materials science,and cell biology will open up undreamed-of possibili-ties in diagnostics and therapy. Challenges include 4-Dimaging, e.g. for beating heart diagnostics, coupling ofmicrosystems to neurons, e.g. neural prostheses, the ap-plication of new biomaterials with surface modificationsat the nanoscale, e.g. for the fabrication of a lifelongstable joining of hip prostheses, and the computer mod-eling of a virtual patient for the verification of diagnosisand direction of therapy.
Protection of patients, cost reduction and the con-sideration of progress in medicine as well as thetechnological state-of-the-art are significant challengesfor the development of medical products. Hopefully thisSpringer Handbook will assist in the continued develop-ment of new medical products that will enhance the wellbeing of patients.
The editors would like to thank the authors for theirfruitful, successful and collegial cooperation. It wasa pleasure for us to collect views from the differentfields of medical technology and bring them togetherin the handbook. Special thanks to Dr. Werner Skolaut,Senior Manager Springer Handbooks, and Dr. ThomasDitzinger, Senior Editor Engineering/Applied Sciences,from Springer publishing for their time, help and kindsupport.
May 2011Rüdiger Kramme TitiseeKlaus-Peter Hoffmann St. IngbertRobert S. Pozos San Diego
VII
About the Editors
Rüdiger Kramme, Graduate Engineer, studied Biomedical and Hospital Engineeringas well as Economics in Gießen and Freiburg, Germany. After his studies, he acquiredseveral years of professional experience in sales, marketing and human resources de-velopment in the medical device industry for consumer and investment capital goods.Since 1993 he is working for the German Federal State of Baden-Württemberg andthe German Federal Armed Forces, where he is involved in planning and project de-velopment of University Hospitals and Military Medical Facilities in Germany andabroad. He is a lecturer for Medical Engineering at the University of Applied Sciencesin Gießen, Germany. Rüdiger Kramme has authored numerous scientific publicationsin magazines and books, and is the founder and editor of the Springer standard workMedizintechnik, which will be published in its fourth edition in 2011, as well as theSpringer Dictionary Technische Medizin.
Klaus-Peter Hoffmann received his Doctorate degree in Biomedical Engineeringfrom the University of Technology in Ilmenau, Germany, in 1987. He is currentlyProfessor of Biomedical Engineering at the University of Applied Sciences in Saar-brueck, and Head of the Department of Medical Engineering and Neuroprostheticsat the Fraunhofer Institute for Biomedical Engineering in St. Ingbert. His main re-search interests include methods and devices of Clinical Neurophysiology especiallyNeuromonitoring and saccadic eye movement as well as the use of Microsystems inmedicine especially sensors and actuators for Neuroprostheses. He is also active in thefield of cognitive technical systems. He has coordinated various European and nationalresearch projects, has published more than 200 journal papers, conference papers andbook chapters. He is member of several scientific societies as well as in the advisoryboard of the journal Das Neurophysiologie-Labor. Since 2004, Professor Hoffmannhas led the Expert Group Neuroprosthetics in the Initiative Micromedicine of of theGerman Association for Electrical, Electronic & Information Technologies (VDE). Heis also member of the Technical Committee on Cardiopulmonary Systems of the IEEEEngineering in Medicine and Biology Society.
Robert Pozos, Professor of Biology at San Diego State University, has been activelyengaged in numerous studies utilizing various biomedical technologies to study humanperformance in extreme environments. His expertise extends to motor control studiesin which he has two patents dealing with quantification of fatigue generated duringtyping using dynamic finger force measurements. His current studies deal with thequantification of surface electromyographic signals during various athletic events uti-lizing wifi technology. In addition he is continuing his studies that combine the use ofNIRS measurements with EMG signals during movement.
IX
List of Authors
Dino AccotoUniversità Campus Bio-Medico di Roma
CIR – Center for Integrated Research
Via A. Del Portillo
00128 Rome, Italy
e-mail: [email protected]
Albert J. AugustinStädtisches Klinikum Karlsruhe
Augenklinik
Moltkestr. 90
76133 Karlsruhe, Germany
e-mail: [email protected]
Natasha Avilae-medicis
26 rue George Sand
75016 Paris, France
e-mail: [email protected]
Michael BatemanUniversity of Minnesota
Department of Biomedical Engineering and
Surgery
420 Delaware St. SE
Minneapolis, MN 55455, USA
e-mail: [email protected]
Andreas BermannSiemens Healthcare
Imaging and Therapy Division, SYNGO
Henkestr. 127
91052 Erlangen, Germany
e-mail: [email protected]
Ulrich BöcklerSorin Group Deutschland GmbH
Lindberghstr. 25
80939 München, Germany
e-mail: [email protected]
Armin BolzKarlsruhe Institute of Technology
Institute for Biomedical Engineering
Kaiserstr. 12
76128 Karlsruhe, Germany
e-mail: [email protected]
Jörn BorgertPhilips Technologie GmbH Forschungslaboratorien
Tomographic Imaging Group
Röntgenstr. 24–26
22335 Hamburg, Germany
e-mail: [email protected]
Michael BornSan Diego State University
Department of Biology
5500 Campanile Drive
San Diego, CA 92182, USA
e-mail: [email protected]
Guenther BraunUniversity Medical Center Freiburg
Paediatrics and Adolescent Medicine
Mathildenstr. 1
79106 Freiburg, Germany
e-mail: [email protected]
Dirk BüchelMedical Faculty of Tübingen
Ernst-Simon-Str. 16
72072 Tübingen, Germany
e-mail: [email protected]
Thorsten M. BuzugUniversity of Lübeck
Institute of Medical Engineering
Ratzeburger Allee 160
23538 Lübeck, Germany
e-mail: [email protected]
X List of Authors
Marco CapogrossoScuola Superiore Sant Anna
ARTS lab
Piazza Martiri della Liberta, 33
56100 Pisa, Italy
e-mail: [email protected]
Peter H. CossmannMed Tech Consulting
Säntisstr. 10
5430 Wettingen, Switzerland
e-mail: [email protected]
Andreas DemosthenousUniversity College London
Electronic and Electrical Engineering
Torrington Place
London, WC1E 7JE, UK
e-mail: [email protected]
Thomas M. DesernoRWTH Aachen University
Pauwelsstr. 30
52057 Aachen, Germany
e-mail: [email protected]
Nick DonaldsonUniversity College London
Medical Physics & Bioengineering
Gower St.
London, WC1E 6BT, UK
e-mail: [email protected]
William K. DurfeeUniversity of Minnesota
Department of Mechanical Engineering
111 Church St SE
Minneapolis, MN 55455, USA
e-mail: [email protected]
Günter Edlingerg.tec medical engineering GmbH
Herbersteinstr. 60
8020 Graz, Austria
e-mail: [email protected]
Amir EftekharImperial College London,
South Kensington Campus
Centre for Bio-Inspired Technology
London, SW7 2AZ, UK
e-mail: [email protected]
Mariana FernandesUniversity of Minho
Department of Industrial Electronics,
DEI – Campus de Azurém
4800-058 Guimarães, Portugal
e-mail: [email protected]
Eduardo FernandezUniversidad Miguel Hernández
Bioengineering Institute
Avenida de la Universidad, s/n
03202 Elche, Spain
e-mail: [email protected]
Fabiola Fernandez-GutierrezUniversity of Dundee
Institute for Medical Science and Technology
1 Wurzburg Loan, Dundee Medipark
Dundee, DD2 1FD, UK
e-mail: [email protected]
Celso P. FigueiredoUniversity of Minho, Campus de Azurém
Department of Industrial Electronics
4800-058 Guimarães, Portugal
e-mail: [email protected]
Harald FischerCreamedix GmbH
Königsberger Str. 2
76356 Weingarten, Germany
e-mail: [email protected]
Martin R. FischerPrivate University Witten/Herdecke gGmbH
Fakultät für Gesundheit
Alfred-Herrhausen-Str. 50
58448 Witten, Germany
e-mail: [email protected]
List of Authors XI
Óscar S. GamaUniversidade do Minho, Campus de Gualtar
Departamento de Informática
4710-057 Braga, Portugal
e-mail: [email protected]
Stephan GarbeUniversity Hospital of Bonn
Radiology Department
Sigmund-Freud-Str. 25
53105 Bonn, Germany
e-mail: [email protected]
Belinda GarnerImperial College London,
South Kensington Campus
Institute of Biomedical Engineering
London, SW7 2AZ, UK
e-mail: [email protected]
Armin GärtnerIngenieurbüro für Medizintechnik
Edith-Stein-Weg 8
40699 Erkrath, Germany
e-mail: [email protected]
Bernhard GleichPhilips Technologie GmbH
Tomographic Imaging Group
Röntgenstr. 24–26
22335 Hamburg, Germany
e-mail: [email protected]
Rudolf GötzAloka GmbH
Halskestr. 25
47877 Willich, Germany
e-mail: [email protected]
Christoph Gugerg.tec medical engineering GmbH, Guger
Technologies OG
Sierningstr. 14
4521 Schiedlberg, Austria
e-mail: [email protected]
Eugenio GuglielmelliUniversita’ Campus Bio-Medico
CIR – Center For Integrated Research
Via Alvaro Del Portillo 21
00128 Rome, Italy
e-mail: [email protected]
Martin HaagHeilbronn University
Medical Informatics
Max-Planck-Str. 39
74081 Heilbronn, Germany
e-mail: [email protected]
Reiner HaagLawton GmbH & Co. KG
Württemberger Str. 23
78567 Fridingen, Germany
e-mail: [email protected]
Peter HaasUniversity of Applied Sciences and Arts Dortmund
Medical Informatics
Emil-Figge-Str. 42
44147 Dortmund, Germany
e-mail: [email protected]
Andreas HahnSorin Group Deutschland GmbH
General Management
Lindberghstr. 25
80939 München, Germany
e-mail: [email protected]
Sibylle HanusTextile Research Institute Thuringia-Vogtland
Textile Structures and Materials
Zeulenrodaer Str. 42
07973 Greiz, Germany
e-mail: [email protected]
Michael HeinleinMednovo Medical Software Solutions GmbH
Hohenzollerndamm 150
14199 Berlin, Germany
e-mail: [email protected]
XII List of Authors
Ewald HennigDeutsches Herzzentrum Berlin
Augustenburger Platz 1
13353 Berlin, Germany
e-mail: [email protected]
Roland HentschelUniversitätsklinikum Freiburg
Neonatologie/Intensivmedizin, Zentrum für
Kinder- und Jugendmedizin
Mathildenstr. 1
79106 Freiburg, Germany
e-mail: [email protected]
Roland HetzerDeutsches Herzzentrum Berlin
Augustenburger Platz 1
13353 Berlin, Germany
e-mail: [email protected]
Lothar HeuserKlinikum der Ruhr-Universität Bochum
Institut für Diagnostische & Interventionelle
Radiologie, Knappschaftskrankenhaus
In der Schornau 23–25
44892 Bochum, Germany
e-mail: [email protected]
Ullrich HieronymiDräger Medical Deutschland GmbH
Moislinger Allee 53–55
23558 Lübeck, Germany
e-mail: [email protected]
Robert HitchcockUniversity of Utah
Bioengineering
Salt Lake City, UT 84112, USA
e-mail: [email protected]
Gerhard HoffmannOrangedental GmbH & Co KG
Aspachstr. 11
88400 Biberach, Germany
e-mail: [email protected]
Klaus-Peter HoffmannFraunhofer Institute for Biomedical Engineering
Medical Engineering and Neuroprosthetics
Emsheimer Str. 48
66386 St. Ingbert, Germany
e-mail: [email protected]
Gerald C. HolstJCD Publishing Company
Winter Park, FL 32789, USA
e-mail: [email protected]
Sebastian HothUniversity of Heidelberg
ENT Hospital – Audiology
Im Neuenheimer Feld 400
69120 Heidelberg, Germany
e-mail: [email protected]
Stephen A. HowardUniversity of Minnesota
Department of Biomedical Engineering and
Surgery
420 Delaware St. SE
Minneapolis, MN 55455, USA
e-mail: [email protected]
Bernhard HugKLS Martin GmbH + Co. KG
Am Gansacker 1b
79224 Umkirch, Germany
e-mail: [email protected]
Paul A. IaizzoUniversity of Minnesota
Department of Surgery
420 Delaware St. SE
Minneapolis, MN 55455, USA
e-mail: [email protected]
Erwin ImmelUniversity of Dundee
Institute for Medical Science and Technology
Wurzburg Loan
Dundee, DD2 1FD, UK
e-mail: [email protected]
List of Authors XIII
Klaus-Martin IrionKarl Storz GmbH & Co. KG
Mittelstr. 8
78532 Tuttlingen, Germany
e-mail: [email protected]
Heinz-Michael JustKlinikum Nürnberg
Institute of Hospital Epidemiology, Medical
Microbiology and Infectious Diseases
Prof.-Ernst-Nathan-Str. 1
90419 Nürnberg, Germany
e-mail: [email protected]
Daniel W. KauffUniversity Medicine of the Johannes Gutenberg
University Mainz
Department of General and Abdominal Surgery
Langenbeckstr. 1
55131 Mainz, Germany
e-mail: [email protected]
Rüdiger KlarUniversitätsklinik Freiburg
Institut für Medizinische Biometrie und
Medizinische Informatik
Stefan-Meier-Str. 26
79104 Freiburg, Germany
e-mail: [email protected]
Werner KneistUniversity Medicine of the Johannes Gutenberg
University Mainz
Department of General and Abdominal Surgery
Langenbeckstr. 1
55131 Mainz, Germany
e-mail: [email protected]
Klaus P. KochUniversity of Applied Sciences Trier
Department of Engineering
54293 Schneidershof, Trier, Germany
e-mail: [email protected]
Heike KrammeFuchsweg 14
79822 Titisee, Germany
e-mail: [email protected]
Rüdiger KrammeFuchsweg 14
79822 Titisee, Germany
e-mail: [email protected]
Ursula KrechelUniversity Clinic Freiburg
IT-Department
Robert-Koch-Str. 1
79106 Freiburg, Germany
e-mail: [email protected]
Harald KronbergAm Hohen Rain 6
64720 Michelstadt, Germany
e-mail: [email protected]
Klaus A. KuhnTechnische Universität München (TUM)
Institute of Medical Statistics and Epidemiology
München, Germany
e-mail: [email protected]
Bernhard KulikMaquet GmbH & Co. KG
Kehler Str. 31
76437 Rastatt, Germany
e-mail: [email protected]
Timothy G. LaskeMedtronic, Inc.
8200 Coral Sea St. NE.
Mounds View, MN 55112, USA
e-mail: [email protected]
Martin LeonhardKarl Storz GmbH & Co. KG
Research and Technology
Mittelstr. 8
78532 Tuttlingen, Germany
e-mail: [email protected]
Xiao LiuUniversity College London
Department of Electronic and Electrical
Engineering
Torrington Place
London, WC1E 7JE, UK
e-mail: [email protected]
XIV List of Authors
Martin MaierPhilips Healthcare
Hewlett-Packard-Str. 2
71034 Böblingen, Germany
e-mail: [email protected]
Giovanni MaioUniversity of Freiburg
Institute of Bioethics and History of Medicine
Stefan-Meier-Str. 26
79104 Freiburg, Germany
e-mail: [email protected]
Albrecht MalkmusGE Medical Systems Information Technologies
Munzinger Str. 5
79111 Freiburg, Germany
e-mail: [email protected]
Kei MasaniToronto Rehabilitation Institute
Lyndhurst Centre
520 Sutherland Drive
Toronto, Ontario M4G 3V9, Canada
e-mail: [email protected]
Ulrich MaternwwH-c GmbH
Ernst-Simon-Str. 16
72072 Tübingen, Germany
e-mail: [email protected]
John McNultySan Diego State University
Department of Biology
5500 Campanile Drive
San Diego, CA 92182, USA
e-mail: [email protected]
Andreas MelzerUniversity Dundee
IMSaT
1 Würzburg Loan
Dundee, Scottland DD2 1FD, UK
e-mail: [email protected]
Paulo M. MendesUniversity of Minho, Campus de Azurém
Department of Industrial Electronics
4800-058 Guimarães, Portugal
e-mail: [email protected]
Silvestro MiceraETH Zürich, ETL K 10.1
Institut für Automatik
Physikstr. 3
8092 Zürich, Switzerland
e-mail: [email protected]
Kostis MichelakisImperial College London,
South Kensington Campus
Institute of Biomedical Engineering
London, SW7 2AZ, UK
e-mail: [email protected]
Uwe MöhringTextile Research Institute Thuringia-Vogtland
Zeulenrodaer Str. 42–44
07973 Greiz, Germany
e-mail: [email protected]
Wolfgang Müller-WittigNanyang Technological University (NTU)
Fraunhofer IDM@NTU
Nanyang Avenue
639798 Singapore
e-mail: [email protected]
Andreas NeudeckTextile Research Institute Thuringia-Vogtland
Zeulenrodaer Str. 44
07973 Greiz, Germany
e-mail: [email protected]
Wolfgang R. NitzSiemens AG Healthcare Sector
Allee am Röthelheimpark 2
91052 Erlangen, Germany
e-mail: [email protected]
Heike OschatzTextile Research Institute Thuringia-Vogtland
Textile Structures and Materials
Zeulenrodaer Str. 42
07973 Greiz, Germany
e-mail: [email protected]
List of Authors XV
Ernst PelikanUniversity Medical Center Freiburg
Hospital Computer Department
Agnesenstr. 6–8
79106 Freiburg, Germany
e-mail: [email protected]
Thomas PeynDräger Medical AG & Co. KG
Department for Respiratory Care
Lübeck, Germany
e-mail: [email protected]
Doris PommiSiemens Healthcare
Siemensstr. 1
91301 Forchheim, Germany
e-mail: [email protected]
Milos R. PopovicUniversity of Toronto
Rehabilitation Engineering Laboratory, Institute of
Biomaterials and Biomedical Engineering
164 College St.
Toronto, Ontario M5S 3G9, Canada
e-mail: [email protected]
Robert S. PozosSan Diego State University
Department of Biology
5500 Campanile Dr.
San Diego, CA 92182-4616, USA
e-mail: [email protected]
Anna Radomska-Botelho MonizImperial College London,
South Kensington Campus
Institute of Biomedical Engineering
London, SW7 2AZ, UK
e-mail: [email protected]
Stanisa RaspopovicScuola Superiore Sant Anna
ARTS lab
Piazza Martiri della Liberta, 33
56100 Pisa, Italy
e-mail: [email protected]
Annette ReinhardtKlinikum Nürnberg
Institute of Hospital Epidemiology
Prof.-Ernst-Nathan-Str. 1
90419 Nürnberg, Germany
e-mail:
Cristiano RizzoMicromed S.p.A.
Via Giotto, 2
31021 Mogliano Veneto (TV), Italy
e-mail: [email protected]
Eckhard RoggenkampKlinikum Nuremberg
Institute of Hospital Epidemiology
Prof.-Ernst-Nathan-Str. 1
90419 Nürnberg, Germany
e-mail:
Christopher RolfesUniversity of Minnesota
Department of Biomedical Engineering and
Surgery
420 Delaware St. SE
Minneapolis, MN 55455, USA
e-mail: [email protected]
Christian RotschFraunhofer Institute for Machine Tools and
Forming Technology IWU
Department Adaptronics and Acoustics
Nöthnitzer Str. 44
01187 Dresden, Germany
e-mail: [email protected]
Georg-Friedemann RustRendoscopy AG
Grubmühlerfeldstr. 54
82131 Gauting, Germany
e-mail: [email protected]
Christina SampognaUniversity of Cambridge
Newmarket, Suffolk C88 7YY, UK
e-mail: [email protected]
XVI List of Authors
Gregor SchaefersMR:comp GmbH
Buschgrundstr. 33
45894 Gelsenkirchen, Germany
e-mail: [email protected]
Rolf M. SchlegelmilchSMT medical GmbH & Co.
Im Kreuz 9
97076 Würzburg, Germany
e-mail: [email protected]
Oliver ScholzHTW Saarland,
University of Applied Sciences
Goebenstr. 40
66117 Saarbrücken, Germany
e-mail: [email protected]
Frank SchönAloka Holding Europe AG
Steinhauserstr. 74
6300 Zug, Switzerland
e-mail: [email protected]
Arthur SchultzHannover Medical School
EEG Monitoring Research Group
Carl-Neuberg-Str. 1
30625 Hannover, Germany
e-mail: [email protected]
Barbara SchultzHannover Medical School
Informatik/Biometrie
Podbielskistr. 380
30659 Hannover, Germany
e-mail: [email protected]
Dirk SchulzeDDZ Breisgau
Kaiser-Joseph-Str. 263
79098 Freiburg, Germany
e-mail: [email protected]
Wilhelm SchütteKreiskrankenhaus Gummersbach, Academic
Teaching Hospital of the University of Cologne
Department of Medical Radiation Physics
Wilhelm-Breckow-Allee 20
51643 Gummersbach, Germany
e-mail: [email protected]
Danny SchwabeTextile Research Institute Thuringia-Vogtland
Zeulenrodaer Str. 44
07973 Greiz, Germany
e-mail: [email protected]
Sanjiv SharmaImperial College London,
South Kensington Campus
Institute of Biomedical Engineering
London, SW7 2AZ, UK
e-mail: [email protected]
Erich SiegelDräger Medical AG & Co. KG
Moislinger Allee 53–55
23558 Lübeck, Germany
e-mail: [email protected]
Florian SolzbacherUniversity of Utah
Electrical and Computer Engineering
Salt Lake City, UT 84112, USA
e-mail: [email protected]
Silvia SterziUniversità Campus Bio-Medico
Physical Medicine and Rehabilitation
Via Alvaro del Portillo 21
00128 Rome, Italy
e-mail: [email protected]
Wilfried StorzGebrüder Martin GmbH & Co. KG
Ludwigstaler Str. 132
78532 Tuttlingen, Germany
e-mail: [email protected]
List of Authors XVII
Dirk SunderbrinkSiemens AG – Healthcare Sector
Imaging and Therapy Department
Hartmannstr. 16
91301 Forchheim, Germany
e-mail: [email protected]
Hajo TanckMednovo Medical Software Solutions GmbH
Hohenzollerndamm 150
14199 Berlin, Germany
e-mail: [email protected]
Prashant TathireddyUniversity of Utah
Electrical and Computer Engineering
Salt Lake City, UT 84112, USA
e-mail: [email protected]
Rachel ToomeyUniversity of Dundee
Institute for Medical Science and Technology
1 Wurzburg Loan, Dundee Medipark
Dundee, DD2 1FD, UK
e-mail: [email protected]
Iasonas F. TriantisSensors Systems and Circuits Research Group
Department of Electronic and Electrical
Engineering
University College London
London, WC1E 7JE, UK
e-mail: [email protected]
Jakub TrzebinskiImperial College London,
South Kensington Campus
Institute of Biomedical Engineering
London, SW7 2AZ, UK
e-mail: [email protected]
Friedrich UeberleHamburg University of Applied Sciences
Department of Life Sciences/Biomedical
Technology
Lohbrügger Kirchstr. 65
21033 Hamburg, Germany
e-mail: [email protected]
Hans-Peter UhligÖsterreicher Str. 69a
01279 Dresden, Germany
e-mail: [email protected]
Jörg VienkenFresenius Medical Care
Else Kroener Str. 1
61342 Bad Homburg, Germany
e-mail: [email protected]
Udo VogesKarlsruher Institut für Technologie
Institut für Angewandte Informatik
Hermann-von-Helmholtz-Platz 1
76344 Eggenstein-Leopoldshafen, Germany
e-mail: [email protected]
Birgit WackerPhilips Healthcare
Hewlett-Packard Str. 2
71034 Böblingen, Germany
e-mail: [email protected]
Golam Abu ZakariaHospital of the University of Cologne
Department of Medical Radiation Physics
Wilhelm-Breckow-Allee 20
51643 Gummersbach, Germany
e-mail: [email protected]
Christian ZapfSiemens AG – Healthcare Sector
Imaging and Therapy – SYNGO
Hartmannstr. 16
91052 Erlangen, Germany
e-mail: [email protected]
Frank ZgodaLaser- und Medizin-Technologie GmbH
Fabeckstr. 60–62
14195 Berlin, Germany
e-mail: [email protected]
Loredana ZolloUniversità Campus Bio-Medico di Roma
Laboratory of Biomedical Robotics and
Biomicrosystems
Via Álvaro Del Portillo, 21
00128 Rome, Italy
e-mail: [email protected]
XIX
Contents
List of Abbreviations ................................................................................. XXXVII
Part A Medical Technology Basics
1 Technology in Medicine:Its Role and Significance in Terms of Health PolicyRüdiger Kramme, Heike Kramme .............................................................. 31.1 A Short History .............................................................................. 31.2 Early Breakthroughs of Medical Technology .................................... 31.3 Analog to Digital ........................................................................... 41.4 Health Policy ................................................................................. 51.5 New Key Areas............................................................................... 51.6 Innovation Versus Financial Resources ........................................... 6
2 Medicine Is More Than Applied Technology for Human BeingsGiovanni Maio ......................................................................................... 72.1 Technology Suggests Feasibility and Controllability ......................... 72.2 Technology Knows No Bounds ........................................................ 82.3 Technology Is Unable to Answer the Question of Meaning ............... 92.4 Technology Alone Does Not Make Medicine Humane ....................... 9References .............................................................................................. 10
3 Hygiene in Medical TechnologyHeinz-Michael Just, Eckhard Roggenkamp, Annette Reinhardt .................. 113.1 Background .................................................................................. 123.2 Causes of Infection ........................................................................ 133.3 Vaccinations ................................................................................. 133.4 Disinfection Methods ..................................................................... 143.5 Sterilization Methods..................................................................... 213.6 Hygiene of Noninvasive Technology Equipment .............................. 253.7 Hygiene of Invasive Technology Equipment .................................... 263.8 Practical Examples......................................................................... 263.9 Regulations ................................................................................... 31References .............................................................................................. 33
4 Technical Safety of Electrical Medical Technology Equipmentand SystemsRüdiger Kramme, Hans-Peter Uhlig .......................................................... 354.1 General Information Regarding the Safety of Technical Systems ....... 364.2 Attaining Safety in Medical Institutions .......................................... 364.3 Minimum Requirements for ME Equipment ..................................... 37
XX Contents
4.4 Areas Used for Medical Purposes .................................................... 404.5 Electrical Systems According to the Nature of the Connection
to Earth ........................................................................................ 424.6 Protection Against Shock Currents .................................................. 424.7 Power Supply ................................................................................ 444.8 Power Sources for Safety Purposes with Accumulators ..................... 444.9 Final Circuits and Plug Sockets ....................................................... 454.10 Static Electricity ............................................................................. 454.11 Electromagnetic Compatibility ........................................................ 464.12 Conclusions ................................................................................... 47References .............................................................................................. 47
5 Quality Management in Medical TechnologyAlbrecht Malkmus .................................................................................... 495.1 Objectives of a Quality Management System ................................... 495.2 Elements of a Quality Management System ..................................... 545.3 Organization of a Quality Management System ............................... 545.4 Implementation of a QMS .............................................................. 565.5 Product Quality ............................................................................. 575.6 Concluding Remarks ...................................................................... 57References .............................................................................................. 58
6 Usability of Medical DevicesUlrich Matern, Dirk Büchel........................................................................ 596.1 What Is Usability? .......................................................................... 596.2 Usability in Medical Technology – Obligation or Opportunity? .......... 606.3 Usability in Medical Technology – Why?.......................................... 616.4 Development of Usable Devices – How Is this Done? ....................... 626.5 Testing of Usable Devices – How Is this Done?................................. 646.6 Assessment of Usability ................................................................. 676.7 Usability Development, Testing, and Assessment – An Example ....... 67References .............................................................................................. 70
Part B Functional Diagnostics Devices
7 Basic Diagnostics in CardiologyRüdiger Kramme...................................................................................... 757.1 Electrocardiography....................................................................... 757.2 Electrocardiograph Equipment Technology and PC ECG .................... 767.3 ECG Methods ................................................................................. 797.4 Lead Systems ................................................................................ 807.5 Methodological Notes .................................................................... 837.6 The Diagnostic Value of the ECG...................................................... 837.7 Complications ............................................................................... 847.8 Technical Safety Aspects of ECG Systems .......................................... 847.9 Long-Term ECG .............................................................................. 84
Contents XXI
7.10 Long-Term ECG Systems ................................................................. 857.11 Computer-Based Assessment ......................................................... 857.12 Heart Rate Variability and Heart Rate Turbulence ............................ 877.13 Indications for Long-Term Electrocardiography ............................... 877.14 The Significance of the Long-Term ECG ........................................... 877.15 The Exercise ECG ............................................................................ 887.16 Equipment Technology .................................................................. 887.17 Reduced Exercise ECG Leads ........................................................... 897.18 Automatic ST Measuring Programs .................................................. 907.19 Exercise Test .................................................................................. 907.20 Methodological Notes .................................................................... 937.21 The Diagnostic Value of Ergometry .................................................. 937.22 Indications ................................................................................... 937.23 Abort Criteria and Safety Measures ................................................. 937.24 Technical Safety Aspects................................................................. 947.25 Notes on Planning ......................................................................... 94Further Reading ...................................................................................... 94
8 Pulmonary Function TestingRolf M. Schlegelmilch, Rüdiger Kramme .................................................... 958.1 Spirometry .................................................................................... 958.2 Advanced Cardiopulmonary Function Testing .................................. 105References .............................................................................................. 116
9 Devices and Methods in Clinical NeurophysiologyKlaus-Peter Hoffmann, Ursula Krechel ...................................................... 1199.1 Basics ........................................................................................... 1199.2 Electroencephalograph .................................................................. 1299.3 Electromyograph ........................................................................... 138Further Reading ...................................................................................... 157
10 Sleep Diagnostic SystemsKlaus-Peter Hoffmann, Robert S. Pozos .................................................... 15910.1 Function and Application .............................................................. 15910.2 Sleep Diagnostics, Sleep Laboratories, and Sleep Apneas ................. 16010.3 Technology ................................................................................... 16210.4 Sleep Diagnostic Procedures ........................................................... 16510.5 Signal Recording and Signal Processing .......................................... 16610.6 Fields of Application ...................................................................... 17110.7 Methodical Instructions ................................................................. 17210.8 Medical Significance of Sleep Diagnostics ....................................... 17310.9 Therapy ........................................................................................ 17510.10 Safety Aspects ............................................................................... 17610.11 Planning Advice ............................................................................ 176Further Reading ...................................................................................... 176
XXII Contents
11 NystagmographyKlaus-Peter Hoffmann, Eduardo Fernandez .............................................. 17911.1 Application ................................................................................... 17911.2 Eye Movements ............................................................................. 18011.3 Technology and Methods ............................................................... 18111.4 Methods ....................................................................................... 18411.5 Signal Recording and Signal Processing .......................................... 18711.6 Medical Significance ...................................................................... 18711.7 Safety Aspects ............................................................................... 18811.8 Spatial Planning ............................................................................ 188References .............................................................................................. 189
12 AudiometrySebastian Hoth ........................................................................................ 19112.1 Physical, Technical and Physiological Bases of Audiometry .............. 19112.2 Behavioral Audiometric Assessment ............................................... 20012.3 Objective Audiometric Assessment .................................................. 21212.4 Technical Hearing Devices .............................................................. 228References .............................................................................................. 242
13 Measurement Techniques in OphthalmologyAlbert J. Augustin .................................................................................... 24513.1 Measurement of Intraocular Pressure ............................................. 24613.2 Optical Coherence Tomography (OCT)............................................... 24713.3 Laser-Scanning Tomography
with the Heidelberg Retina Tomograph (HRT) .................................. 24913.4 Nerve Fiber Polarimetry with GDx ................................................... 25113.5 The Rostock Cornea Module (Confocal Laser Microscope) .................. 25213.6 Automatic Refractometry ............................................................... 25213.7 Visually Evoked Potential (VEP) ....................................................... 25313.8 The Ganzfeld ERG (Ganzfeld Electroretinogram) ............................... 25413.9 Pattern Electroretinography (Pattern ERG, PERG) ............................. 25713.10 Multifocal ERG (mfERG) .................................................................. 25913.11 Electrooculograms (EOG) ................................................................ 26013.12 Adaptometry ................................................................................. 26113.13 Aberrometry (Wavefront Analysis)................................................... 26113.14 Keratometry .................................................................................. 26313.15 Retinoscopy or Skiascopy ............................................................... 26313.16 Ultrasound .................................................................................... 26313.17 Corneal Topography ....................................................................... 26513.18 The Orbscan .................................................................................. 26513.19 Scheimpflug Examination .............................................................. 26713.20 Fluorescence Angiography of the Retina (Sodium-Fluorescein) ........ 26713.21 Fluorescence Angiography of the Retina (Indocyanine Green) .......... 26913.22 Visual Field Measurement (Perimetry) ............................................. 26913.23 Exophthalmometry ........................................................................ 271References .............................................................................................. 271
Contents XXIII
14 Functional Force Assessment of Skeletal MusclesPaul A. Iaizzo, William K. Durfee .............................................................. 27314.1 The Need for Skeletal Muscle Force Assessment ............................... 27314.2 Manual Muscle Strength Testing ..................................................... 27514.3 Advanced Muscle Assessment Methods ........................................... 27814.4 Stimulated Muscle Force Assessment .............................................. 27914.5 Stimulated Muscle Force Assessment in Animal Models ................... 28314.6 Conclusion .................................................................................... 285References .............................................................................................. 285
Part C Medical Imaging
15 Digital RadiographyLothar Heuser .......................................................................................... 29115.1 Historical Background .................................................................... 29115.2 From Analog to Digital Image ......................................................... 29215.3 Digital Imaging Systems in Radiology ............................................. 29615.4 Digital Image Processing ................................................................ 30515.5 Image Communication and Archiving ............................................. 307References .............................................................................................. 309
16 Computed TomographyThorsten M. Buzug ................................................................................... 31116.1 Background .................................................................................. 31116.2 Milestones of Computed Tomography ............................................. 31316.3 Computed Tomography Technology ................................................ 31816.4 Image Reconstruction .................................................................... 32316.5 Scan Planning and Applications ..................................................... 32916.6 Dose ............................................................................................. 33516.7 Special System Designs .................................................................. 338References .............................................................................................. 341
17 Ultrasound DiagnosticsRudolf Götz, Frank Schön ......................................................................... 34317.1 Basic Physical Principles ................................................................ 34417.2 Visualization of the Blood Flow and Vascular System ....................... 34817.3 Equipment Technology .................................................................. 35017.4 Three-Dimensional Ultrasound (3-D, Real-Time 3-D) ...................... 36017.5 Operation of an Ultrasound Unit .................................................... 367Further Reading ...................................................................................... 367
18 Medical Infrared ImagingGerald C. Holst, Thorsten M. Buzug ........................................................... 36918.1 Background .................................................................................. 36918.2 Infrared System Design .................................................................. 37018.3 Infrared Physics ............................................................................ 372
XXIV Contents
18.4 IR Imaging in Medical Applications................................................. 37318.5 Specific Applications ...................................................................... 37418.6 Limitations of IR Imaging in Medical Applications ........................... 37718.7 Summary ...................................................................................... 377References .............................................................................................. 378
19 EndoscopyMartin Leonhard, Klaus-Martin Irion ........................................................ 37919.1 Basics ........................................................................................... 38019.2 Endoscopes and Endoscopic Accessories ......................................... 38219.3 Integrated Operating Theaters........................................................ 39119.4 Medical Applications ..................................................................... 39319.5 Tissue Differentiation .................................................................... 39419.6 Further Future Developments ......................................................... 398References .............................................................................................. 402
20 Cone-Beam Computed Tomography and NavigationDirk Schulze, Gerhard Hoffmann............................................................... 40520.1 Technical Background of Dental Digital Volume Tomography ........... 40520.2 Areas of Application of Dental CBCT................................................. 408References .............................................................................................. 413
21 Interventional Radiology – AngiographyDoris Pommi ............................................................................................ 41721.1 Definition of Digital Subtraction Angiography ................................. 41721.2 Application Range for Angiography ................................................ 41921.3 Advantages of Interventional Radiology Procedures ........................ 42021.4 Trends of Development .................................................................. 420Further Reading ...................................................................................... 421
22 Near-Infrared Spectroscopy (NIRS)John McNulty, Michael Born, Robert S. Pozos............................................. 42322.1 NIRS – Technical ............................................................................ 42322.2 NIRS Technology: Engineering Aspects ............................................ 42522.3 Instrumentation and Equipment .................................................... 42722.4 New Developments: Multidepth Differential Approach .................... 43022.5 Clinical Application and Study of NIRS ............................................ 43122.6 Does Skin Blood Flow Affect NIRS Measurements? ............................ 43322.7 Future of NIRS ............................................................................... 436References .............................................................................................. 437
23 Magnetic Resonance ImagingWolfgang R. Nitz ..................................................................................... 43923.1 History of MRI ............................................................................... 43923.2 MRI – System Components ............................................................. 441
Contents XXV
23.3 MRI – Basic Principles and Applications .......................................... 44623.4 MRI – Safety-Relevant Aspects ....................................................... 45323.5 MRI – Pictures of the Future .......................................................... 456References .............................................................................................. 458
24 Magnetic Particle ImagingJörn Borgert, Bernhard Gleich, Thorsten M. Buzug..................................... 46124.1 Introduction ................................................................................. 46124.2 A Brief History of Magnetic Particle Imaging.................................... 46224.3 How Magnetic Particle Imaging Works ............................................ 46324.4 From Data to Images – Reconstruction ........................................... 46824.5 Beyond General Purpose Systems – Special Geometry ..................... 47024.6 Putting MPI to Use – Applications .................................................. 472References .............................................................................................. 474
25 MR-Guided Interventions and SurgeryAndreas Melzer, Erwin Immel, Rachel Toomey,
Fabiola Fernandez-Gutierrez.................................................................... 47725.1 MRI Basics ..................................................................................... 47825.2 MRI Image Guidance for Interventions and Surgery in Comparison
with CT and Ultrasound ................................................................. 47925.3 MR Systems Design and Setup for Interventions and Surgery ........... 47925.4 Instruments for Interventional and Intraoperative MRI ................... 48225.5 MR-Applicable Endoscopic Instrument Systems ............................... 48225.6 Instrument Representation and Tracking in MRI .............................. 48325.7 MR-Guided Robotics and Navigation .............................................. 48525.8 Hybrid Multimodal Imaging for MR-Guided Diagnosis and Therapy .. 49125.9 Therapeutic MR-Guided Imaging .................................................... 49325.10 MR-Guided Delivery of Implants .................................................... 49425.11 Conclusions ................................................................................... 498References .............................................................................................. 498
26 Devices and Materials in MRIGregor Schaefers, Andreas Melzer ............................................................. 50326.1 MR Safety ...................................................................................... 50426.2 Interactions in the MR Environment ............................................... 50426.3 Examples of MR Artifacts Caused by Medical Devices ........................ 51026.4 Evaluation of MRI Artifacts of Implants ........................................... 51226.5 MR Safety Labeling ........................................................................ 51426.6 Interpretation of MR Labeling ........................................................ 51726.7 Discussion ..................................................................................... 518References .............................................................................................. 519
XXVI Contents
Part D Therapeutic Devices
27 Long-Term Ventilators for Intensive TherapyThomas Peyn ........................................................................................... 52527.1 Tasks of the Ventilator ................................................................... 52527.2 Function and Components of a Long-Term Ventilator ...................... 52627.3 Technical Implementation ............................................................ 52927.4 Controlling the Ventilator .............................................................. 53027.5 Ventilation Procedures .................................................................. 53127.6 Ventilation Extras and Special Functions......................................... 54027.7 Patient Monitoring and Alarm Limits .............................................. 54327.8 Weaning Strategy and SmartCare/PS ............................................... 543
28 Defibrillators and ICD SystemsRüdiger Kramme...................................................................................... 54528.1 Defibrillator Technology ................................................................. 54628.2 Therapeutic Intervention ............................................................... 54928.3 Methodological Notes .................................................................... 55028.4 Complications ............................................................................... 55128.5 Technical Safety Aspects................................................................. 55128.6 Implantable Cardioverter-Defibrillators .......................................... 551References .............................................................................................. 556
29 Laser SystemsFrank Zgoda ............................................................................................ 55729.1 History of the Laser ....................................................................... 55829.2 Physics and Technology ................................................................. 55829.3 Application Methods ..................................................................... 56429.4 Biophysical Effects on Tissue .......................................................... 56429.5 Laser Types in Medicine ................................................................. 56729.6 Fields of Use ................................................................................. 57129.7 Safety Aspects ............................................................................... 57429.8 Future Prospects ............................................................................ 577References .............................................................................................. 577
30 Inhalational Anesthesia DevicesErich Siegel.............................................................................................. 57930.1 Anesthesia Devices in General Anesthesia ....................................... 57930.2 Functional Principle, Medical Aspects ............................................. 58030.3 Functional Principle of the Main Components ................................. 58230.4 Safe Operation Prerequisites .......................................................... 594Further Reading ...................................................................................... 595
31 Extracorporeal Blood Purification SystemsJörg Vienken ............................................................................................ 59731.1 Historical Perspective .................................................................... 59831.2 Blood Purification for the Therapy of Renal Failure ......................... 600
Contents XXVII
31.3 Dialysis Machines and Additional Equipment: Use and Conditions ... 61131.4 Blood Purification in Liver Replacement Therapy............................. 614References .............................................................................................. 617
32 Heart–Lung MachinesUlrich Böckler, Andreas Hahn ................................................................... 62132.1 Historical Development of Extracorporeal Circulation....................... 62132.2 Extracorporeal Circulation .............................................................. 62332.3 Structure and Function of the Heart–Lung Machine ........................ 62332.4 Components of the Heart–Lung Machine ........................................ 62732.5 Extracorporeal Circulation .............................................................. 62932.6 Differentiation of Heart–Lung Machines ......................................... 63532.7 Aspects of Technical Safety ............................................................. 63632.8 Prospects for Further Development ................................................. 637References .............................................................................................. 638
33 Application of Shock Waves and Pressure Pulses in MedicineFriedrich Ueberle...................................................................................... 64133.1 Introduction – Historical Development ........................................... 64233.2 Definitions of Physical Terms: Acoustics – Sound Waves –
Pressure Pulses – Shock Waves ....................................................... 64333.3 The Acoustic Field of a Lithotripter –
Basics of Measurement Technology ................................................ 64933.4 Generation of Pressure Pulses for Extracorporeal Lithotripsy (ESWL)
and Extracorporeal Shock Wave Therapy (ESWT) ............................... 66033.5 Extracorporeal Lithotripsy (ESWL)
and Extracorporeal Shock Wave Therapy (ESWT) in Practice .............. 66433.6 The Patient ................................................................................... 66733.7 Assessment of the Clinical Efficiency of Lithotripters ....................... 66833.8 Associations and Societies for Lithotripsy and Pressure Pulse
Therapy ........................................................................................ 670References .............................................................................................. 671
34 High-Frequency SurgeryBernhard Hug, Reiner Haag ..................................................................... 67734.1 Development of High-Frequency Surgery ........................................ 67834.2 Physical and Technical Principles ................................................... 68134.3 Technology and Techniques ........................................................... 68434.4 Types of Current and Their Application ........................................... 68739.5 Methodical Instructions for Application and Safety ......................... 69734.6 Outlook ......................................................................................... 700References .............................................................................................. 701
35 Medical Radiation TherapyPeter H. Cossmann ................................................................................... 70335.1 X-Radiation .................................................................................. 70435.2 Historical Development of Radiation Therapy .................................. 704
XXVIII Contents
35.3 Physical and Technical Principles of Radiation Physics..................... 70535.4 Forms of Therapy ........................................................................... 70835.5 Equipment Technology for the Generation of Radiation .................. 71035.6 Special Techniques and Newer Developments in Teletherapy ........... 716References .............................................................................................. 721
36 Mechanical Circulatory Support SystemsRoland Hetzer, Ewald Hennig ................................................................... 72336.1 Introduction – History ................................................................... 72436.2 Indications for Application of MCSS................................................. 72536.3 Classification of MCSS ..................................................................... 72736.4 Today’s Systems ............................................................................ 72836.5 Complications ............................................................................... 73936.6 Technical Follow-Up and Care ........................................................ 74236.7 Psychosomatic Syndromes and Quality of Life During Treatment
with MCS ....................................................................................... 74236.8 Overview and Outlook ................................................................... 744References .............................................................................................. 747
37 Neural Interfaces for Implanted StimulatorsXiao Liu, Andreas Demosthenous, Nick Donaldson ..................................... 74937.1 Stimulating Electrodes ................................................................... 75137.2 Implantable Cable Management .................................................... 75337.3 Design of Stimulator Output Stage .................................................. 75637.4 Conclusions ................................................................................... 763References .............................................................................................. 764
38 Cardiac Pacemaker SystemsArmin Bolz .............................................................................................. 76738.1 Structure of a Pacemaker System .................................................... 76838.2 The Functionality of a Cardiac Pacemaker ....................................... 77138.3 Stimulation Modes ........................................................................ 774References .............................................................................................. 782
39 Introduction to NeuroprostheticsKlaus-Peter Hoffmann, Silvestro Micera .................................................... 78539.1 Neuroprostheses ........................................................................... 78539.2 Application of Neural Prostheses .................................................... 78739.3 Specific Technological Features ...................................................... 78839.4 Biological–Technical Interface ....................................................... 79039.5 Future Developments .................................................................... 798References .............................................................................................. 799
Contents XXIX
40 Implantable MicrosystemsPrashant Tathireddy, Florian Solzbacher, Robert Hitchcock,
Klaus-Peter Hoffmann ............................................................................. 80140.1 Market, Applications, and Common Requirements .......................... 80140.2 Sensors ......................................................................................... 80540.3 In vitro and in vivo Testing ............................................................ 814References .............................................................................................. 816
41 Visual ProsthesesEduardo Fernandez, Klaus-Peter Hoffmann .............................................. 82141.1 The Case for Artificial Vision ........................................................... 82241.2 Visual Pathways: From Real Vision to Visual Neuroprostheses .......... 82241.3 Current Approaches to Visual Prostheses ......................................... 82441.4 Engineering Visual Neuroprostheses ............................................... 82741.5 Safe and Effective Stimulation of Visual Pathways
Through Multiple Microelectrodes .................................................. 82941.6 Selection of Suitable Subjects for a Visual Prosthesis ....................... 83041.7 Challenges and Future Perspectives ................................................ 831References .............................................................................................. 832
42 Rehabilitation and Therapeutic RoboticsLoredana Zollo, Dino Accoto, Silvia Sterzi, Eugenio Guglielmelli ................. 83542.1 Background .................................................................................. 83542.2 Human-Centered Approach to Rehabilitation Robot Design ............. 83742.3 Robot-Based Measure of Patient’s Performance.............................. 84442.4 Conclusions and Further Readings .................................................. 850References .............................................................................................. 851
43 Cardiac Devices and TestingMichael Bateman, Stephen A. Howard, Christopher Rolfes,
Timothy G. Laske, Paul A. Iaizzo ............................................................... 85543.1 Background .................................................................................. 85643.2 Selected Landmark Events in Cardiac Devices and Surgery ............... 85643.3 Market Released Cardiac Devices .................................................... 85743.4 Device Development ...................................................................... 85743.5 The Anatomy of a Device ................................................................ 86743.6 Emerging Cardiac Device Technology .............................................. 87143.7 Conclusions ................................................................................... 874References .............................................................................................. 874
44 Functional Electrical Stimulation in Rehabilitationand NeurorehabilitationKei Masani, Milos R. Popovic .................................................................... 87744.1 The Basis of Electrical Stimulation .................................................. 87844.2 Neuroprosthetic Use of FES ............................................................. 883
XXX Contents
44.3 FES Therapy ................................................................................... 88944.4 Other Uses of Electrical Stimulation ................................................ 89044.5 Concluding Remarks ...................................................................... 890References .............................................................................................. 890
45 Treatment Planning and Patient TreatmentGolam Abu Zakaria, Wilhelm Schütte, Stephan Garbe ................................ 89745.1 Principles of Radiotherapy and Treatment Planning ........................ 89845.2 Imaging in Treatment Planning...................................................... 90145.3 Basic Techniques in External Beam Therapy .................................... 90245.4 Target Volumes and Organ at Risk .................................................. 90945.5 Modern Treatment Planning Systems .............................................. 91045.6 Simulation of the Patient and the First Treatment........................... 91545.7 Quality Control in Radiation Therapy .............................................. 917References .............................................................................................. 919
Part E Monitoring
46 Recording and Processing of BiosignalsKlaus-Peter Hoffmann, Florian Solzbacher................................................ 92346.1 Measuring in Medicine .................................................................. 92346.2 Registration of Biological Signals ................................................... 93446.3 Measurement and Signal Analysis from a Metrological Point of View 94046.4 Test Planning and Clinical Studies .................................................. 944Further Reading ...................................................................................... 945
47 Monitoring SystemsUllrich Hieronymi, Rüdiger Kramme .......................................................... 94747.1 Fields of Use for Patient Monitoring Systems ................................... 94847.2 Types of Monitors .......................................................................... 94947.3 Monitor Screen Content ................................................................. 95147.4 Handling ...................................................................................... 95247.5 Alarms and Events ......................................................................... 95247.6 Trend Display ................................................................................ 95247.7 Automatic Calculations .................................................................. 95347.8 Advanced System Properties .......................................................... 95347.9 Central Monitoring and Documentation .......................................... 953Further Reading ...................................................................................... 954
48 Cardiovascular MonitoringUllrich Hieronymi, Rüdiger Kramme .......................................................... 95548.1 Monitoring the Cardiac Function .................................................... 95548.2 Monitoring the Circulatory Function (Hemodynamic Monitoring) ...... 957References .............................................................................................. 969
Contents XXXI
49 Respiratory Monitoring and Pulse OximetryUllrich Hieronymi, Rüdiger Kramme, Harald Kronberg ............................... 97149.1 Respiratory Mechanics ................................................................... 97149.2 Gas Exchange ................................................................................ 973References .............................................................................................. 985
50 Temperature MonitoringRüdiger Kramme, Ullrich Hieronymi .......................................................... 98750.1 Hyperthermia and Hypothermia ..................................................... 98750.2 Measuring Sites for Temperature Measurement ............................... 98750.3 Temperature Sensors and Probes.................................................... 98750.4 Methodological Notes .................................................................... 989Further Reading ...................................................................................... 990
51 Cerebral MonitoringBarbara Schultz, Arthur Schultz, Harald Kronberg ..................................... 99151.1 EEG Monitoring ............................................................................. 99151.2 Intracranial Pressure ..................................................................... 995References .............................................................................................. 1000
52 Brain Computer InterfaceGünter Edlinger, Cristiano Rizzo, Christoph Guger...................................... 100352.1 Introduction to BCI ........................................................................ 100352.2 Measuring Brain Activity ................................................................ 100452.3 BCI System Structure ...................................................................... 100552.4 Conclusions ................................................................................... 1014References .............................................................................................. 1015
53 Fetal MonitoringBirgit Wacker, Martin Maier...................................................................... 101953.1 Cardiotocography (CTG) .................................................................. 101953.2 Obstetric Monitoring Systems ......................................................... 1022Further Reading ...................................................................................... 1030
54 Neonatal MonitoringRoland Hentschel..................................................................................... 103154.1 Electrocardiogram ......................................................................... 103254.2 Impedance Pneumography ............................................................ 103354.3 Combined Cardiorespiratory Analysis .............................................. 103454.4 Pulse Oximetry .............................................................................. 103554.5 Transcutaneous Measurement of the Partial Pressure ...................... 103754.6 Measurement of the PtcCO2 (Transcapnode) .................................... 103854.7 Measurement of the PtcO2 (Transoxode) ......................................... 103854.8 Monitoring the Oxygenation – Which Method? ............................... 103954.9 Setting Alert Limits and Limit Values............................................... 1040References .............................................................................................. 1041
XXXII Contents
55 Intraoperative NeuromonitoringWerner Kneist, Daniel W. Kauff ................................................................. 104355.1 General Principles ......................................................................... 104355.2 Neuromonitoring Signals ............................................................... 104655.3 Scope of Application ...................................................................... 104855.4 Quality Management ..................................................................... 105655.5 Guidelines and Legal Aspects ......................................................... 1056Further Reading ...................................................................................... 1057
56 Ionic Neural SensingIasonas F. Triantis, Anna Radomska-Botelho Moniz, Kostis Michelakis,
Sanjiv Sharma, Jakub Trzebinski, Belinda Garner, Amir Eftekhar ................ 105956.1 Central and Peripheral Nervous System Monitoring ......................... 106056.2 Chemistry of Neural Activity ........................................................... 106456.3 Chemical Neural Sensing Technology and Challenges....................... 106556.4 Conclusion .................................................................................... 1069References .............................................................................................. 1070
Part F Medical Information Processing and Communication
57 Fusing Medical Engineering and Information Technology –Structure, Integration and Process OptimizationHajo Tanck, Michael Heinlein ................................................................... 107557.1 Standards of Interfaces .................................................................. 107657.2 Data Structure ............................................................................... 107757.3 Integrating the Healthcare Enterprise ............................................. 107857.4 Integration of Medical Devices ....................................................... 107857.5 Sample Integration – From Findings to Medical Documentation ...... 108257.6 Résumé ........................................................................................ 1082Further Reading ...................................................................................... 1083
58 Communicating Medical Systems and NetworksArmin Gärtner ......................................................................................... 108558.1 Medical Networks .......................................................................... 108558.2 Requirements for Medical Networks ............................................... 108658.3 Interconnected Medical Networks .................................................. 108758.4 Risk Management, DIN EN ISO 14971 ................................................ 108858.5 Shared Networks ........................................................................... 108958.6 Security Aspects of Medical Networks from a Regulatory Viewpoint .. 109258.7 Future Standard IEC 80001-1 .......................................................... 1093References .............................................................................................. 1093
59 Hospital Information SystemsPeter Haas, Klaus A. Kuhn ........................................................................ 109559.1 Background .................................................................................. 109559.2 Necessity, Objectives, and Benefits of Comprehensive HIS................ 1096
Contents XXXIII
59.3 Dimensions of IT Support ............................................................... 109859.4 Case Study .................................................................................... 109959.5 Architecture and Components of HIS ............................................... 110359.6 Current Trends and Prospects ......................................................... 110859.7 Selection and Implementation of HIS ............................................. 111059.8 Conclusion .................................................................................... 1117References .............................................................................................. 1118
60 Telemedicine in GermanyRüdiger Klar, Ernst Pelikan....................................................................... 111960.1 The Peculiar Features of German Telemedicine ............................... 112060.2 Consequences of the Peculiarities of the German System
for Telemedicine ........................................................................... 1125References .............................................................................................. 1126
61 Telemedicine Using Active ImplantsKlaus P. Koch, Oliver Scholz ...................................................................... 112961.1 Telemedicine in the Operating Theater ........................................... 112961.2 Telemedicine in Domestic Care ....................................................... 113061.3 Implant Telemetry ......................................................................... 113161.4 Inclusion of Active Medical Implants in Telemedicine Systems ......... 1136References .............................................................................................. 1136
62 Fundamentals of Medical Image ProcessingThomas M. Deserno.................................................................................. 113962.1 Background .................................................................................. 113962.2 Remarks on the Terminology.......................................................... 114162.3 Image Enhancement ..................................................................... 114262.4 Feature Extraction ......................................................................... 114762.5 Segmentation ............................................................................... 114862.6 Classification ................................................................................. 115462.7 Quantitative Measurements ........................................................... 115762.8 Interpretation ............................................................................... 115862.9 Image Data Visualization ............................................................... 115862.10 Image Management ...................................................................... 116162.11 Conclusion and Outlook ................................................................. 1163References .............................................................................................. 1165
63 Virtual Reality in MedicineWolfgang Müller-Wittig ........................................................................... 116763.1 Virtual Reality ............................................................................... 116863.2 Medical Applications ..................................................................... 116863.3 VR-Based Medical Simulation ........................................................ 117463.4 Model Generation – Virtual Anatomy ............................................. 117563.5 Manipulations – Surgical Interventions .......................................... 117863.6 Outlook ......................................................................................... 1182References .............................................................................................. 1184
XXXIV Contents
64 Computer-Supported Teaching and Learning Systems in MedicineMartin Haag, Martin R. Fischer................................................................. 118764.1 Historical Development.................................................................. 118764.2 Moves Towards the Reform of Medical Studies ................................ 118964.3 Developing Learning and Teaching Systems .................................... 118964.4 Learning Environments .................................................................. 119364.5 Application Scenarios for Learning and Teaching Systems ................ 119564.6 Status of and Outlook for e-Learning in Medicine ........................... 1195References .............................................................................................. 1197
65 PACS and RISChristian Zapf, Andreas Bermann, Dirk Sunderbrink .................................. 119965.1 Radiological Workflow ................................................................... 120065.2 Integrating PACS/RIS into the Hospital Environment ........................ 120565.3 State-of-the-Art IT Infrastructure .................................................. 120665.4 Summary ...................................................................................... 1208References .............................................................................................. 1208
66 3-D Postprocessing in Virtual EndoscopyGeorg-Friedemann Rust ........................................................................... 120966.1 What Is Virtual Reality? .................................................................. 121066.2 Why Virtual Reality? ....................................................................... 121066.3 Advantages of 3-D Visualization ..................................................... 121066.4 Conclusions ................................................................................... 1216References .............................................................................................. 1216
67 e-Health – Ambient Assisted Living and Personal Health SystemsNatasha Avila, Christina Sampogna.......................................................... 121767.1 Background .................................................................................. 121867.2 AAL and PHS Approaches ................................................................ 122167.3 Benefits and Challenges Ahead ...................................................... 123467.4 Conclusion .................................................................................... 1241References .............................................................................................. 1243
68 Electrical Stimulation of the Nervous SystemStanisa Raspopovic, Marco Capogrosso, Silvestro Micera ............................ 124768.1 Background .................................................................................. 124768.2 Biophysics Models of Neuronal Response to External Fields ............. 124868.3 Finite Element (FE) Models ............................................................. 125268.4 Conclusion .................................................................................... 1256References .............................................................................................. 1256
Contents XXXV
Part G Equipment and Tools
69 Operating Tables – the Surgeon’s WorkplaceBernhard Kulik ........................................................................................ 126169.1 The History of the Operating Table .................................................. 126269.2 The OR Table System ...................................................................... 126369.3 Technology of Operating Room Table Systems ................................. 126469.4 Safe Patient Positioning................................................................. 126869.5 Preparation: Care, Maintenance, and Hygiene ................................ 1271Further Reading ...................................................................................... 1272
70 Medical RoboticsHarald Fischer, Udo Voges ........................................................................ 127370.1 Fundamentals ............................................................................... 127370.2 Development of Medical Robots ..................................................... 127470.3 Overview of Systems ...................................................................... 127570.4 Medical Applications ..................................................................... 128070.5 Technical Aspects .......................................................................... 128170.6 Outlook ......................................................................................... 1282References .............................................................................................. 1283
71 IncubatorsGuenther Braun, Roland Hentschel ........................................................... 128571.1 Historical Background .................................................................... 128571.2 Construction and Function of an Incubator ..................................... 128671.3 Incubator Models .......................................................................... 128771.4 Risks of Incubator Therapy ............................................................. 128971.5 Hygiene ........................................................................................ 128971.6 Unsolved Problems ........................................................................ 1290References .............................................................................................. 1290
72 Surgical ScissorsReiner Haag, Wilfried Storz ...................................................................... 129172.1 The History of Scissors .................................................................... 129272.2 The Function and Design of Scissors ............................................... 129372.3 Materials ...................................................................................... 129472.4 Manufacture of Surgical Scissors ..................................................... 129472.5 Diversification Overview ................................................................ 129772.6 Handling and Care ........................................................................ 131072.7 Inspection, Testing, and Care ......................................................... 131472.8 Packaging ..................................................................................... 131472.9 Current Terminology ...................................................................... 131572.10 Steam Sterilization with Saturated Steam ....................................... 131572.11 Quality Characteristics.................................................................... 131672.12 Future Developments .................................................................... 131772.13 Bipolar Scissors ............................................................................. 1318References .............................................................................................. 1319
XXXVI Contents
73 Intelligent Textiles and TrendsChristian Rotsch, Sibylle Hanus, Danny Schwabe, Heike Oschatz,
Andreas Neudeck, Uwe Möhring ............................................................... 132173.1 Textile Manufacturing Technologies and Applications ...................... 132173.2 Sensory Applications of Textiles ...................................................... 132673.3 Active Textiles – Therapeutical Applications .................................... 133073.4 Passive Medical Textiles for Therapy ............................................... 1333References .............................................................................................. 1335
74 Electronics in MedicinePaulo M. Mendes, Celso P. Figueiredo, Mariana Fernandes, Óscar S. Gama . 133774.1 Basics ........................................................................................... 133874.2 Electronic Sensing ......................................................................... 134174.3 Electronics for Wireless Health Monitoring ...................................... 134474.4 Power Supply ................................................................................ 134874.5 Wearable Medical Electronics ......................................................... 135374.6 Electronics in Medicine at Work...................................................... 1358References .............................................................................................. 1373
Appendix.................................................................................................... 1377Acknowledgements ................................................................................... 1391About the Authors ..................................................................................... 1393Detailed Contents ...................................................................................... 1415Subject Index ............................................................................................. 1455
XXXVII
List of Abbreviations
μTAS micro total analytical system1-D one-dimensional2-D two-dimensional3-D three-dimensional3-D CSI three-dimensional chemical shift imaging4-D four-dimensional
A
A-mode amplitude modeA/D analogue/digitalAAA abdominal aortic aneurysmAAL ambient assisted livingAAMI Association for the Advancement of
Medical InstrumentationABI auditory brainstem implantABLB alternate binaural loudness balanceABR auditory brainstem responsesAC air conductionAC alternating currentACC American College of CardiologyACD absolute claudication distanceACT activated clotting timeADC analog-to-digital converterADHD attention-deficit/hyperactivity disorderADL advanced distributed learningADSL asymmetric digital subscriber lineADT admission, discharge, and transferAEC automatic exposure controlAED automated external defibrillatorAEP auditory evoked potentialAEP acoustic evoked potentialAGC automatic gain controlAGC/i input-controlled automatic gain controlAGC/o output-controlled automatic gain controlAGIT Arbeitsgemeinschaft InformationstechnikAHA American Heart AssociationAI artificial intelligenceAIx augmentation indexACF autocorrelation functionALL acute lymphatic leukemiaALS amyotrophic lateral sclerosisAMFR amplitude modulation following responseAMI alternate mark inversionAMI auditory midbrain implantAMIGO advanced multimodality image-guided
operating roomAML acute myeloic leukaemiaANSD auditory neuropathy spectrum disorderAP anaesthetic proofAPD auditory processing disorder
APOD adaptive probe off detectionAPm mean arterial pressureAR augmented realityAR automated refractometerARM Aspen return monitorART algebraic reconstruction techniqueASB assisted spontaneous breathingASD atrial septal defectASHA American Speech and Hearing
AssociationASICS application-specific integrated circuitASL arterial spin labelingASSR auditory steady-state responseASTM American Society for Testing and
MaterialsAT adaptive tripoleATC automatic tube compensationATMP advanced therapy medicinal productATP antitachycardic pacingATP adenosine triphosphateATPD ambient temperature and pressure, dryATPS ambient temperature and pressure,
saturatedATS American Thoracic SocietyAV atrioventricularAVC automatic volume controlAWIGS advanced workplace for image guided
surgery
B
B-mode brightness modeB2B business-to-businessBAHA bone-anchored hearing aidBANG bis acrylamide nitrogen gelatinBAR billing and accounting requestBART breathing-adapted radiotherapyBC bone conductionBCI brain–computer interfaceBCM body composition monitorBER bit error ratioBERA brainstem electric response audiometryBERA brainstem evoked response audiometryBF body floatingBGA blood gas analysisBGO bismuth germanateBILD binaural intelligibility level differenceBIS bispectral indexbit binary digitBL blended learningBMLD binaural masking level difference
XXXVIII List of Abbreviations
BOLD blood oxygenation-dependent imagingBPEG British Pacing and Electrophysiology
GroupBPH benign prostate tissueBPS battery-supported power supplyBSE bovine spongiform encephalopathyBSN body sensor networkBTB bridge to bridgeBTD bridge to decisionBTE behind the earBTPS body temperature and pressure, saturatedBTR bridge to recoveryBTT bridge a patient to transplantationBVAD biventricular assist deviceBfArM Bundesinstitut für Arzneimittel und
MedizinprodukteBipol-TUR bipolar transurethral resection
C
CABG coronary artery bypass graftingCAD computer-aided diagnosisCAD coronary artery diseaseCAL computer-assisted learningCAM computer-aided manufactureCAP contention access periodCAPD central auditory processing disorderCAS compressed analog stimulation strategyCAS computer-aided surgeryCAT computerized axial tomographyCBCT cone-beam computed tomographyCBF cerebral blood flowCBI computer-based instructionCBIR content-based image retrievalCBT computer-based trainingCBV cerebral blood volumeCCC China compulsory certificateCCD charge-coupled deviceCCITT Comité Consultatif International
Téléphonique et TélégraphiqueCCR continuity of care recordCCU camera control unitCCU coronary care unitCCU critical care unitCD compact discCD-ROM compact disc read-only memoryCDA clinical document architectureCDC Center for Disease ControlCDM central display and control moduleCE contractile elementCEN Comité Européen de NormalisationCENELEC European Committee for Electrotechnical
StandardizationCERA cortical electric response audiometryCF cardiac floatingCFP contention-free period
CGM continuous glucose monitoringCGMS continuous glucose monitoring systemCGS centimeter-gram-secondCI cochlear implantCI confidence intervalCIC completely in the canalCIM ceramic injection moldingcIONM continuous intraoperative
neuromonitoringCIRS computer integrated radiology systemCJD Creutzfeldt–Jakob diseaseCL comfortable stimulation levelCLT color lookup tableCMCT central motor conduction timeCML chronic myeloic leukemiaCMOS complementary
metal–oxide–semiconductorCMRR common mode rejection ratioCNAP continuous noninvasive arterial pressureCNC computer numerically controlledCNCA Certification and Accreditation
Administration of the Peoples Republicof China
CNS central nervous systemCNT carbon nanotubeCNV choroidal neovascularizationsCNV contingent negative variationCO cardiac outputCPA continuous positive airwayCPAP continuous positive airway pressureCPK creatine phosphokineaseCPOE computerized physician order entryCPP cerebral perfusion pressureCPU central processing unitCQC China Quality Certification CentreCQM contact quality monitorCR computed radiographyCROS contralateral routing of signalsCRT cardiac resynchronization therapyCRT cathode-ray tubeCSCL computer-supported
cooperative/collaborative learningCSCN customer support clinical networkCSCW computer-supported cooperative workCSF cerebrospinal fluidCSMA-CA carrier sense multiple access with
collision avoidanceCSSD central sterilization supply departmentCT computer tomograph(y)CTA CT-angiographyCTG cardiotocographyCTI computed tomography imagingCTV clinical target volumeCUNY City University of New YorkCVC central venous catheterCVD cardiovascular disease
List of Abbreviations XXXIX
CVD congenital vascular disorderCVP central venous pressureCW continuous waveCWRUVA Case Western Reserve
University/Department of VeteransAffairs
D
D2D doctor-to-doctorDAC digital-to-analog converterDART dynamic adaptive radiotherapyDAS data-acquisition systemDAS detector angular subtenseDBS deep brain stimulationDC direct currentDCT dynamic contour tonometryDECT digital enhanced cordless
telecommunicationDFM design for manufactureDFT defibrillation thresholdDFT detail financial transactionDGSL Deutsche Gesellschaft für
StosswellenlithotripsieDGSM German Sleep SocietyDHZB Deutsches Herzzentrum BerlinDICOM digital imaging and communications in
medicineDIHK Deutscher Industrie- und
HandelskammertagDIMDI Deutsches Institut für Medizinische
Dokumentation und InformationDIT differential infrared thermographyDMD Duchenne muscular dystrophyDNA deoxyribonucleic acidDNEP descending neurogenic evoked potentialDOF degree of freedomDPF differential path lengthDPOAE distortion product otoacoustic emissionDQE dose quantum efficiencyDR direct radiographyDR dual rateDRC dynamic range compressionDRG diagnosis related groupDRL driven right legDRR digitally reconstructed radiographDRR dynamic range reductionDSA digital subtraction angiographyDSL desired speech levelDSO distribution system operatorDSP digital signal processorDT destination therapyDTI diffusion tensor imagingDTL Dawson–Trick–LitzkowDVD digital versatile discDVH dose volume histogram
DWI diffusion-weighted imagingDoD Department of DefenseDoF degree of freedom
E
E-ABR evoked auditory brainstem responsee-HC electronic health cardEAEP early auditory evoked potentialEAS electric and acoustic stimulationEBCT electron-beam computed tomographyEBUS endobronchial ultrasonographyECC enhanced cornea compensationECC extracorporeal circulationECG electrocardiogramECG electrocardiograph(y)ECMO extracorporeal circulatory supportECW extracellular waterECoG electrocortical gridECoG electrocorticographyED energy flux densityEDG electrodermographyEDP electronic data processingEDTA ethylenediaminetetraacetic acidEEG electroencephalogramEEG electroencephalograph(y)eFA electronic case recordEFOV extended field of viewEFT electrical fast transientEG electrogramEGFET extended gate field effect transistorEGG electrogastrographyEHG electrohysterographyEHR electronic health recordEHT electrohydrothermosationEIRP effective isotropically radiated powerEIS electrochemical impedance spectroscopyEL electroluminescentEM electromagneticEMC electromagnetic compatibilityEMEA European Medicine AgencyEMG electromyogramEMG electromyograph(y)EMI Electric and Musical Industries Ltd.EMI electromagnetic interferenceEMS electrical muscle stimulationEMSE electromagnetic sourceENG electronystagmographyENG electroneurogramENG electroneurographyENT ear, nose, throatEO electroopticEO ethylene oxideEOAE evoked otoacoustic emissionEOG electrooculogramEOG electrooculography
XL List of Abbreviations
EP electropolishedEP evoked potentialEPR electronic patient recordEPSP excitatory postsynaptic potentialER enhanced realityERA electric response audiometryERB equivalent rectangular bandwidthERD event-related desynchronizationERG electroretinographyERG electroretinogramERP early receptor potentialERP event related potentialERS European Respiratory SocietyERS event-related synchronizationERV expiratory reserve volumeESC European Society of CardiologyESD electrostatic dischargeESWL extracorporeal shock wave lithotripsyESWT extracorporeal shock wave treatmentESWT extracorporeal shock wave therapyETL echo train lengthETO ethylene oxideETSI European Telecommunications Standards
InstituteEUG ectopic pregnancy (Extrauteringravidität)EUS endosonographicEUTox European Uremic Toxin Working GroupEVC expiration volume capacity
F
FA flip angleFAEP brainstem auditory evoked potentials
(frühe akustisch evozierte Potentiale)FBP filtered back-projectionFCC US Federal Communications
CommissionFDA US Food and Drug AdministrationFDI Fédération Dentaire InternationaleFDL flashlamp pumped dye laserFDRC full dynamic range compressionFEL free-electron laserFEM finite element methodFES functional electrical stimulationFET FES therapyFFE fast field echoFFP field free pointffs form/fill/sealFFT fast Fourier transformationFHN Fitzhugh–NagumoFINE flat interface nerve electrodeFIR far-infraredFIV1 forced expiratory volume in 1 sFLAIR fluid-attenuated inversion recoveryFLASH fast low-angle shotFMD fibromuscular dysplasia
FMEA failure modes and effects analysisfMRI functional magnetic resonance imagingFMT floating mass transducerFO formaldehydeFOV field of viewFP Framework ProgrammeFRC functional residual capacityFSE fast spin echoFSK frequency shift keyingFSM Frederick S. MikelbergFSP fine structure processingFT Fourier transformationFTIR Fourier transform infraredFVC forced vital capacityFWHM full width at half maximumFoV field of view
G
GA genetic algorithmGCP good clinical practiceGEDV global end-diastolic volumeGEF global ejection fractionGIF graphics interchange formatGM gray matterGMDS Society for Medical Informatics,
Biometry and EpidemiologyGMG Law on the Modernization of HealthcareGOx glucose oxidaseGPU graphics processing unitGRAPPA generalized autocalibrating partially
parallel acquisitionGRE gradient echoGS general supplyGSDOM German Society of Dental, Oral and
Craniomandibular SciencesGSM Global System for Mobile
CommunicationsGSR galvanic skin responseGTV gross tumor volumeGTWM Georgia Tech Wearable MotherboardGUI graphical user interface
H
hcg human chorionic gonadotropicHCV hepatitis C virusHD hemodialysisHDD hard-disc driveHDF hemodiafiltrationHDR high-dose rateHEMO hemodialysisHF hemofiltrationHF high frequencyHFCS high-frequency current-switchingHFITT HF-induced interstitial tumor therapy
List of Abbreviations XLI
HH Hodgkin and HuxleyHI hypopnea indexHINT hearing in noise testHIS hospital information systemHL hearing levelHL hearing lossHL7 Health Level 7HLD high level disinfectionHLM heart–lung machineHMD head-mounted displayHME heat and moisture exchangerHMEF heat and moisture exchange filterHPC health professional cardHR heart rateHRT Heidelberg Retina TomographHTX heart transplantHU Hounsfield unitHV Vickers hardnessHb hemoglobinHbt hemoglobin concentrationHpD hematoporphyrin derivative
I
IC inspiratory capacityIC integrated circuitICD implantable cardioverter-defibrillatorICD International Classification of DiseasesICD implantable cardioverter–defibrillatorICD initial claudication distanceICG impedance cardiogramICG indocyanine greenICP intracranial pressureICSD International Classification of Sleep
DisordersICSPE International Commission for the
Standardization of ErgometryApplication
ICT information and communicationtechnology
ICT information and computer technologyICU intensive care unitICW intracellular waterID identification numberIDE investigational device exemptionIDEFIX identification of dental fixturesIEC International Electrotechnical
CommissionIEGM intracardial electrogramIFOV instantaneous field of viewIG insertion gainIGRT image guided radiotherapyIGV intra-thoracic gas volumeIHC inner hair cellIHE integrating healthcare enterprises
IHS inspiratory help systemiIONM intermittent intraoperative
neuromonitoringILR implantable loop recorderILV independent lung ventilationIMAT intensity-modulated arc therapyIMRT intensity-modulated radiotherapyINA instrumentation amplifierIOERT intraoperative electron radiation therapyIOL intraocular lensIOM Institute of MedicineIONM intraoperative neuromonitoringIOP intraocular pressureIP intellectual propertyIPPV intermittent positive pressure ventilationIPSP inhibitory postsynaptic potentialIQ installation qualificationIR infraredIRFI infrared functional imagingIRMA image retrieval in medical applicationsIROG infrared oculographyIRV inspiratory reserve volumeISDN integrated services digital networkISE ion-selective electrodeISF interstitial fluidISFET ion-sensitive field effect transistorISM industrial, scientific, and medicalISO International Standardization
OrganizationIT information technologyITBV intrathoracic blood volumeITGV intra-thoracic gas volumeITS initial transmission slotITU International Telecommunication UnionIVC inspiration vital capacity
J
jnd just noticeable difference
K
KIT Karlsruhe Institute of TechnologyKV health insurance (Krankenversicherung)
L
LAN local area networkLAP left atrial pressureLASER light amplification by stimulated
emission of radiationLCA Leber’s amaurosisLCD liquid-crystal displayLDA linear discriminant analyzerLDH lactate dehydrogenase
XLII List of Abbreviations
LDR low-dose rateLED light-emitting diodeLF low frequencyLFP local field potentialLGN lateral geniculate nucleusLI laser iridotomyLITT laser-induced thermotherapyLLLT low-level laser therapyLLT laser lithotripsyLMS learning management systemLOINC logical observation identifiers names and
codesLPRT low-power, real-time protocolLSHD light spot hydrophoneLTP low-temperature plasma sterilizationLUT look-up tableLVAD left ventricular assist deviceLWIR long-wavelength infraredLiDCO lithium ion dilution
M
M-mode motion modeMAC media access controlMAEP middle latency auditory evoked potentialMAP mean arterial pressureMARS adsorbent recirculating systemMC microcontrollerMCS mechanical circulatory supportMCSS mechanical circulatory support systemMDCT multidetector computed tomographyMDD medical device directiveMDM manage document messageMDR medium-dose rateMDS move during scanMDS myelodysplastic syndromeMDX dystrophic miceME medical electricalME medical engineeringMEA multielectrode arrayMEDARPA medical augmented reality for patientsMEDDEV medical deviceMEG magnetoencephalographyMEMS microelectromechanical systemMEP motor evoked potentialMEQ modified essay questionmfERG multifocal ERGMFI micro flex interconnection techniqueMFT multifrequency tympanometryMHLW Ministry of Health, Labor and WelfareMIB medical information busMICS medical implant communication serviceMIP maximum-intensity projectionMIS minimally invasive surgery
MITOS multimodality image-guided diagnosisand therapy setup
MLC multileaf collimatorMLEM maximum-likelihood expectation
maximizationMLRA middle latency response audiometryMMN mismatch negativityMMS multimedia message serviceMMT manual muscle testingMOD magnetooptical discMOG magnetooculographyMPDA microphotodiode arrayMPE maximum permissible exposureMPI magnetic particle imagingMPI master patient indexMPPS modality performed procedure stepMPR multiplanar reconstructionMPS magnetic particle spectrometerMPS maximum physical frame sizeMR magnetic resonanceMRI magnetic resonance imagingMRS MR spectroscopyMRSA methicillin-resistant staphylococcus
aureusMRT magnetic resonance tomographyMRT minimum resolvable temperatureMRgFUS MR-guided focused ultrasoundMS multiple sclerosisMSCT multislice computer tomographyMSLT multiple sleep latency testMT movement timeMTF modulation transfer functionMTT mean transit timeMUAP motor unit action potentialMUP motor unit potentialMV minute volumeMVCT megavoltage computer tomographyMVP MedBiquitous virtual patientMWIR mid-wavelength infraredMWT maintenance of wakefulness testMb myoglobinMetHb methemoglobinMi mechanical index
N
NA numerical apertureNAA n-acetyl-aspartateNAL National Acoustics LaboratoriesNAS network attached storageNASPE North American Society of Pacing and
ElectrophysiologyNBG NASPE/BPEG generic pacemaker codeNBI narrowband imagingNBP noninvasive blood pressure
List of Abbreviations XLIII
NCIGT National Center for Image GuidedTherapy
nCPAP nasal continuous positive airway pressureNCV nerve conduction velocityNDIR nondispersive infraredNDT nondestructive testingNE neutral electrodeNEDT noise equivalent differential temperatureNET noise equivalent temperatureNETD noise equivalent temperature differenceNFD nephrogenic fibrosing dermopathyNFI nerve fiber indicatorNIBP noninvasive blood pressureNICU neonatal intensive care unitNIHL noise-induced hearing lossNIP needle image plateNIR near-infraredNIRS near-infrared spectroscopyNIV noninvasive ventilationNMES neuromuscular electrical stimulationNMR nuclear magnetic resonanceNN nearest neighborNOTES natural orifice translumenal endoscopic
surgeryNP neural pathwayNRZ no return to zeroNSF nephrogenic systemic fibrosisNTC negative-temperature coefficientNTP normal transmission periodNTSC National Television System CommitteeNYHA New York Heart Association
O
O2Hb oxyhemoglobinO2C oxygen to seeOAE otoacoustic emissionOAR organ at riskOCT optical coherence tomographyODI oxygen desaturation indexOEG open ear gainOHC outer hair cellOID object identifierOKN optokinetic nystagmusOL-HDF online hemodiafiltrationOME otitis media with effusionONH optic nerve headOP operative fieldOPCAB off-pump coronary artery bypassOPS classification of operational procedures
(Germany)OQ operational qualificationOR operating roomORC oxygen ratio controllerORM order message
ORU observation results unsolicitedOSA obstructive sleep apnoeaOSCE objective structured clinical examinationOSI open system interconnectionOT operating theaterOXI oximetry
P
PA polyamidePAAM polyacrylamidePACC patient contact controlPACS picture archiving and communication
systemPAD peripheral arterial diseasePAL pharmaceutical affairs lawPAN polyacrylonitrilePAP pulmonary artery pressurePAPm mean pulmonary artery pressurePAT parallel acquisition techniquePAV proportional assist ventilationPAW airway pressurePBL problem-based learningPC peak clippingPC personal computerPC pressure controlledPC-AC pressure control–assist controlPC-APRV pressure control airway pressure release
ventilationPC-BIPAP pressure control, biphasic positive airway
pressurePC-CMV pressure control-continuous mandatory
ventilationPC-SIMV+ pressure control-synchronized
intermittent mandatory ventilation plusPCB printed circuit boardPCR principal component regressionPCS patient control systemPCV pressure-controlled ventilationPCWP pulmonary capillary wedge pressurePDA patent ductus arteriosusPDA personal digital assistantPDCA plan–do–check–actPDD percentage depth dosePDF portable document formatPDM permanent dynamic monitoringPDMA Pharmaceuticals and Medical Devices
AgencyPDR pulsed-dose ratePDT photodynamic therapyPDw proton density weightingPE parallel elementPE protective earthPEEP positive end-expiratory pressurePEF peak expiratory flow
XLIV List of Abbreviations
PEG polyethylene glycolPELV protective extra low voltagePEMS programmable electrical medical systemPENG photoelectronystagmographyPERG pattern ERGPET positron emission tomographyPF pulmonary functionPFO patent foramen ovalePFT pulmonary function testPHS personal health systemPI perfusion indexPID proportional–integral–derivativePII pulse intensity integralPIN personal identification numberPLS partial least-squaresPLV pressure-limited ventilationPMMA polymethylmethacrylatePMS periodic leg movementPMV pump minute volumePNS peripheral nerve stimulationPNS peripheral nervous systemPPG photoplethysmogramppm parts per millionPPS proportional pressure supportPQ performance qualificationPRF proton resonance frequencyPRF pulse repetition frequencyPRVC pressure regulated volume controlledPS power supplyPS pressure supportPSN pelvic splanchnic nervePSu polysulfonePT perception thresholdPT programmed teachingPTA percutaneous transluminal angioplastyPTCA percutaneous transluminal coronary
angioplastyPTS permanent threshold shiftPTT pulse transit timePTV planned target volumepTX parallel transmitPUK personal unblocking keyPUR polyurethanePUVA psoralen and ultraviolet APVAD paracorporeal ventricular assist devicePVARP postventricular atrial refractory periodPVC polyvinyl chloridePVDF polyvinyl difluoridePVDF polyvinylidene fluoridePVI pleth variability indexPVP polyvinylpyrrolidonePVR pulmonary vascular resistancePW pulsed wavePW pulse widthPWC pulse working capacityPWV pulse wave velocity
Q
QBE query by exampleQM quality managementQMS quality management systemQSRL Q-switched ruby laserQT quasi-tripoleQWIP quantum-well infrared photodetectorQoS quality of service
R
RAID redundant array of independent discsRARE rapid acquisition with relaxation
enhancementRBC red blood cellRCD residual current protective deviceRCTX radiochemotherapyRDI respiratory disturbance indexRECD real ear to coupler differenceREFET reference FETREM rapid eye movementRF radiofrequencyRFID radiofrequency identificationRGB red–green–blueRGRT respiratory guided radiotherapyRIM reference information modelRIS radiology information systemRKI Robert Koch InstituteRLN recurrent laryngeal nerveRMS root mean squareROI region of interestROM range of motionRPE retinal pigment epitheliumRR respiration rateRSNA Radiological Society of North AmericaRST rotation, scale, and translationRT radiation therapyRV residual volumeR&TTE radio and telecommunications terminal
equipment
S
S-MAC sensor MACSA sinoatrialSAN storage area networkSAP systemic arterial pressureSAR specific absorption rateSARS severe acute respiratory syndromeSB spontaneous breathingSBRT stereotactic body radiation therapySCI steered compound imagingSCI spinal cord injurySCORM sharable courseware object reference
model
List of Abbreviations XLV
SCP slow cortical potentialSD standard deviationSE spin echoSE series elementSEM scanning electron microscopysEMG spontaneous electromyographySENSE sensitivity encodingSEP somatosensory evoked potentialSET signal extraction technologySF standard flashSFOAE stimulus frequency otoacoustic emissionSIDS sudden infant death syndromeSIMV synchronized intermittent mandatory
ventilationSISI short increment sensitivity indexSLARSI sacro-lumbar anterior root stimulator
implantSMD surface mount deviceSME small and medium-sized enterprisesSMR sensorimotor rhythmicSMS short message serviceSNOMED Systematized Nomenclature of MedicineSNR signal-to-noise ratioSOA service oriented architectureSOAE spontaneous otoacoustic emissionSOC system-on-a-chipSPECT single photon emission computed
tomographySPGR spoiled gradient recalledSPIN speech in noiseSPIO superparamagnetic iron oxideSPL sound pressure levelSPN-CPAP spontaneous-continuous positive airway
pressureSPN-CPAP/PS spontaneous continuous positive airway
pressure/pressure supportSPN-PPS spontaneous proportional pressure
supportSQUID superconductive quantum interference
deviceSRS stereotactic radiosurgerySRT stereotactic radiotherapySRT speech perception thresholdSSEP somatosensory evoked potentialSSVEP steady-state visually evoked potentialSTAN ST waveform analysisSTIR short-tau inversion recoverySTPD standard temperature and pressure, drySTR scotopic threshold responseSV stroke volumeSVC superior vena cavaSVES ventricular super-extrasystoleSVR systemic vascular resistanceSWI susceptibility-weighted imagingSWIR short-wavelength infraredSkBF skin blood flow
T
TA technical assistantTAH total artificial heartTASP téléassistance en soins de plaiesTBI total body irradiationTC tube compensationTCI target-controlled infusionTCP/IP transmission control protocol/Internet
protocolTDI tissue Doppler imagingTDMA time-division multiple accessTE time of echoTEB thoracic electrical bioimpedanceTEC thermoelectric coolerTEE transesophageal echocardiographytEMG triggered electromyographyTENS transcutaneous electrical nerve
stimulationTEOAE transient evoked otoacoustic emissiontf-LIFE thin-film longitudinal intrafascicular
electrodeTFT thin-film technologyTFT thin-film transistorTHC tissue hemoglobin measurementTHI tissue hemoglobin indexTIFF tagged image file formatTIVA total intravenous anesthesiaTLC total lung capacityTLD thermoluminescent dosimeterTMP transmembrane pressureTMS transcranial magnetic stimulationTN-S terre neutre séparéTOI tissue oxygenation indexTPR total peripheral resistanceTPS treatment planning systemTPU thermoplastic polyurethaneTR time of repetitionTRICKS time-resolved imaging of contrast
kineticsTSE turbo spin echoTSEBT total skin electron beam therapyTT true-tripoleTTDT threshold tone decay testTTP time to peakTTS temporary threshold shiftTTS transdermal therapeutical systemTUR transurethral resectionTUR-B transurethral resection, bladderTUR-P transurethral resection, prostateTV televisionTWIST time-resolved imaging with interleaved
stochastic trajectoryTimCT total imaging matrix with continuous
table movementToF-MRA time-of-flight MR angiography
XLVI List of Abbreviations
U
UCUM Unified Code for Units of MeasureUDP user datagram protocolUEA Utah electrode arrayUITDD ultrasound-induced targeted drug
deliveryULF ultralow frequencyUPG ultrasound pneumographyUPS uninterruptible power supplyURR urea reduction rateUS ultrasoundUSB universal serial busUSRDS United States Renal Data SystemUV ultraviolet
V
VAD ventricular assist deviceVAH Verbund für angewandte HygieneVAP ventilator-associated pneumoniaVC vital capacityVC volume controlledVC-AC volume control-assist controlVC-MMV volume control-mandatory minute
volumeVC-SIMV volume control-synchronized intermittent
mandatory ventilationvCJD variant Creutzfeldt–Jakob diseaseVCT volume computer tomographyVDE Verband der Elektrotechnik, Elektronik
und InformationstechnikVEP visual evoked potentialVES ventricular extrasystoleVG volume guaranteeVLAN virtual local area networkVLF very low frequency
VLWIR very longwave infraredVNA vendor-neutral archiveVOG videooculographyVOR vestibulo-ocular reflexVOT vascular occlusion testVR ventricular rateVR virtual realityVRE vancomycin-resistant enterococcus
faeciumVRT volume rendering techniqueVSV vacuum–steam–vacuumVT tidal volumeVTC videoteleconference
W
W3C World Wide Web ConsortiumWBT web-based trainingWD washer-disinfectorWDRC wide dynamic range compressionWHMS wireless health monitoring systemWIM wireless interface moduleWLAN wireless local area networkWM white matterWOB work of breathingWPW Wolff–Parkinson–White-syndromeWSN wireless sensor network
X
XDS cross-enterprise document sharingXML extensible markup language
Z
ZVEI Zentralverband der ElektrotechnischenIndustrie
1
Medical TPart APart A Medical Technology Basics
1 Technology in Medicine: Its Roleand Significance in Terms of Health PolicyRüdiger Kramme, Titisee, GermanyHeike Kramme, Titisee, Germany
2 Medicine Is More Than Applied Technologyfor Human BeingsGiovanni Maio, Freiburg, Germany
3 Hygiene in Medical TechnologyHeinz-Michael Just, Nürnberg, GermanyEckhard Roggenkamp, Nürnberg, GermanyAnnette Reinhardt, Nürnberg, Germany
4 Technical Safety of Electrical MedicalTechnology Equipment and SystemsRüdiger Kramme, Titisee, GermanyHans-Peter Uhlig, Dresden, Germany
5 Quality Management in Medical TechnologyAlbrecht Malkmus, Freiburg, Germany
6 Usability of Medical DevicesUlrich Matern, Tübingen, GermanyDirk Büchel, Tübingen, Germany
3
Technology i1. Technology in Medicine:Its Role and Significance in Terms of Health Policy
Rüdiger Kramme, Heike Kramme
New avenues in diagnosis and therapy are to-
day increasingly being opened up as a result
of sophisticated and advanced technology, and
at the forefront of this are evolutionary devel-
opments in existing technology. Many medical
devices and pieces of equipment are devel-
oping at lightning speed as a result of digital
technologies, which enable new medical con-
cepts, strategies, and visions to be implemented
faster than ever before. This means that de-
velopments which previously took a decade to
implement are now being introduced at a rate of
one a year. Technology thus not only has a dynamic
interrelationship with medicine; it influences
and shapes modern medical science on the
1.1 A Short History ..................................... 3
1.2 Early Breakthroughsof Medical Technology .......................... 3
1.3 Analog to Digital .................................. 4
1.4 Health Policy ........................................ 5
1.5 New Key Areas ...................................... 5
1.6 Innovation Versus Financial Resources.... 6
basis of new technical possibilities. First-class
health care would be inconceivable without
progress and innovation in the field of medical
technology.
1.1 A Short History
Medicine (from the Latin ars medicı̄na, the art of heal-ing) and technology (from the Greek, meaning skill,craft) have inspired and fascinated mankind since itsearly beginnings. Technical instruments and deviceshave always had their place in medicine. Acupunctureneedles are known to have been used in Far Easternmedicine since approximately 2500 BC. Hippocrates(460–370 BC), the founder of scientific medicine inthe Western world and a prominent doctor of his time,was already using a proctoscope to inspect his pa-tients’ intestines. He also gave descriptions of a varietyof instruments and apparatuses for the treatment of
wounds. These included, for example, apparatuses withweights and straps which, in the case of an arm frac-ture, positioned the broken bones in relation to oneanother, straightened them, and simultaneously immo-bilized them. As striking evidence from archeologicaldigs in the buried town of Pompeii has shown, sophisti-cated instruments and devices for surgical interventionswere already being used in the Roman Empire (from63 BC onwards). The vision aids known as glasses, onwhich many of us rely, are not an achievement of the20th century but had already been invented by a crafts-man at the end of the 13th century.
1.2 Early Breakthroughs of Medical Technology
The first major breakthrough in medical technologyand boom in modern medicine took place around theturn of the 20th century with Röntgen’s discovery of
x-rays in 1895. Although the nomenclature of the elec-trocardiograph (ECG) – which is still in use today –had already been decided by Einthoven in 1895, use
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of the first clinically viable ECG was not possible un-til 1903. In 1896, Riva-Rocci introduced the methodof noninvasive palpatory measurement for determin-ing blood pressure. The electroencephalogram (EEG)was first recorded in 1924 by Berger using a stringgalvanometer. Other milestones in medical technologywere the invention and introduction of the artificial kid-ney (1942), the heart–lung machine (1953), hip-jointprostheses (1960), artificial cardiac valves (1961), andthe first clinical patient monitoring devices (around1965). Criteria which had already been used for classifi-cation in the USA were developed for measurement andstandardization of the ECG according to the Minnesota
Code around 1960. In the early 1940s, the constructionof the first electronic computer ushered in a new era, anda new technology was born which was to revolution-ize medical technology once more: data processing andinformation technology. This new technology overshad-owed all the technological developments which wentbefore it. If a modern calculator were equipped withelectronic components (e.g., transistors) from 40 yearsago, that calculator would require a power of 6000 W,provided by an electricity supply and emitted to the sur-roundings as heat. A weight of 50 kg and cube edgesapproximately 1 m in length would more likely suggestan oven than a calculator.
1.3 Analog to Digital
The radical change in technology from analogue todigital opened up new dimensions in medical technol-ogy: the computer tomograph (CT), which generatescross-sectional images of the body, was developed byHounsfield and Cormack, and a prototype was installedand tested in a hospital in 1971. In 1977, Mansfieldfound success with a breakthrough for medical appli-cations of magnetic resonance tomography using themagnetic resonance method, and the human thorax wasimaged for the first time without the use of x-rays.Unique and sophisticated possibilities in diagnosis wereintroduced by a large-scale medical technology systemwhich is used in nuclear medicine: the positron emis-sion tomograph (PET). As an imaging system, the PETenhances the diagnostic range because it enables repre-sentations of physiological and metabolic processes inthe human body to be determined both quantitativelyand on a location-dependent basis. Molecular imagingwith hybrid PET/CT scanners offers a view of thingswhich had previously not been visible. However, otherhybrids such as ultrasound and magnetic resonanceimaging also not only have the advantage that they offeran image quality which is much more precise and accu-rate in every detail when compared with other imagingmethods, but they can also be used without any expo-sure to radiation. It has so far been possible to reducethe radiation dose for a full body scan to as little as 40%compared with older systems.
As a result of the increasing integration ofcomputer-based systems in x-ray technology, imagingmethods are being redeveloped in ever shorter timecycles. The rapid growth of the spectrum of clinical
applications and the continuous further developmentand implementation of new technologies have not onlyled to an altered and extended range of indications forthese methods. Furthermore, imaging technologies areincreasingly being developed as a complete solution,such as hybrid systems for interventional radiology orintegrated IT solutions (picture archiving and commu-nication system (PACS), radiology information system(RIS), etc.) which aim to optimize processes and thusincrease efficiency in hospitals. The increasing inter-connectedness of technology will change the healthsystem.
To outline the progress and development of all thedevices and achievements in medical technology wouldbe to go beyond the scope of this book. Although med-ical technology is in most cases not original but ratheradopts technological developments from fields such aselectronics, optics, precision engineering, and plasticstechnology among others, and these developments areonly thought of as being part of medical technologywhen applied to living creatures, medical technologyhas nevertheless established itself as a field, and med-ical care today would be unthinkable without it. Thisfact reveals the real significance of medical technology:
Medical technology devices and equipment (includ-ing in the laboratory and research field) are individualor interlinked instruments, apparatuses, machines, ap-pliances, and auxiliary devices, and any necessaryequipment which is used because of its function forthe identification (diagnosis), treatment (therapy), ob-servation (monitoring), and prevention (prophylaxis) ofillness in humans.
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Technology in Medicine: Its Role and Significance in Terms of Health Policy 1.5 New Key Areas 5
1.4 Health Policy
The aim of health policy must be to provide hu-man, modern, high-performance, efficient, and people-orientated medical care both in hospitals and on anambulatory basis, with the focus on the patient. Inthe future, diagnosis and therapy will be adjusted ac-cording to the genetics of the patient, and technicalsolutions will be orientated towards the interaction be-tween diagnosis and therapy. Another trend is thatof orientation towards disease patterns. This aspectis even more important, because the risks of acuteillnesses will increase as a result of ageing society. In-vestment in health care should provide benefits, notonly in terms of administration at the level of individ-ual hospitals and clinics but also in terms of nationaleconomics.
The development of medical technology as anessential part of health care is in permanent in-teraction with the changes in social lifestyles. Thesignificance of medical technology in terms of healthpolicy is therefore essentially based on the followingpoints.
• The quality and security of medical care as a re-sult of continuous modifications and improvementsto diagnostic and therapeutic options and promotionof medical and technological research, and further-more with broad application and extension to largepopulation and patient groups using equipment-based mass screening (e.g., within the scope ofillness prevention).• Shortening the duration of illness or the length ofhospital stay, which will reduce costs and thereforebring about associated benefits in terms of nationaleconomics.• Relieving staff from time-consuming routine jobs.• Meeting the expectations and demand level of thepopulation in terms of the quality of the processesand of the results in health care.
Future developments in technical medicine must begeared towards the additional demands of health care asa result of limited resources.
• Medical technological diagnosis and therapy withhigh cost-savings potential, using environmentallyfriendly equipment and systems.• Further development of minimally invasive proce-dures with the aim of reducing morbidity rates andconvalescence times.• Miniaturized compact systems, which are less timeand cost intensive in terms of installation and ser-vicing.• User-friendly and operationally reliable design,which substantially avoids faulty operation. Inva-sive techniques will increasingly be replaced byless invasive and/or noninvasive techniques, suchas disintegration of kidney and gall stones usinga lithotripter instead of surgical intervention, en-doscopic minimally invasive interventions insteadof conventional surgery, three-dimensional (3-D)echocardiography to show complex malformationsof the heart, pathomorphological changes in the mi-tral or tricuspid valve, and atrial or ventricular septaldefects instead of the complex and high-risk pro-cedure of cardiac catheterization, and imaging thecoronary vessels using magnetic resonance imag-ing instead of contrast angiography or diagnosis bycardiac catheterization.
It is becoming apparent that the boundaries be-tween diagnosis and therapy are becoming increasinglyblurred by the use of current technological solutionssuch as interventional radiological or endoscopic pro-cedures, for example.
Where operative interventions in traditional surgerywere performed using a scalpel and surgical instru-ments, in the foreseeable future these will to a largeextent be replaced by the light and sound of noninvasivesurgery. Successful high-energy ultrasound operationson the brain have already been achieved in the field ofneurosurgery, meaning not only that there are new meth-ods of treatment opening up but that there is even talkof a paradigm shift in neurosurgical therapy. Neurosur-gical treatment by means of ultrasound in the case ofpsychiatric disorders, such as affective psychoses, forexample, should also be possible in the future.
1.5 New Key Areas
A key area of technology in health care of the 21stcentury is telematics, which has the potential to bring
enormous advantages to all those involved in healthcare but will also mean that health care organizations
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are faced with many new organizational, technologi-cal, and legal requirements. In the future, hospitals willbe centers of telemedicine applications. Telemedicalcommunication and systems – that is to say all IT ap-plications in the health care system which are providedvia public or long-distance communications networks –enable large amounts of data to be transferred quickly,
meaning that physical distance is no longer an obsta-cle. This is also a reason for the fact that increasinglygreat importance is placed on telemedicine internation-ally. These endeavors are aimed at developing a uniformplatform for telematics, so that use of modern telecom-munications and information technology will improvethe quality of care and economic efficiency in the future.
1.6 Innovation Versus Financial Resources
Today, limited financial resources in hospitals meanthat it is only rarely possible to introduce and exploitevery technical innovation and possibility. It is there-fore imperative for the user to evaluate any investmentdecisions on a commercial and performance-related ba-sis (e.g., by process-orientated technology assessment,which takes account primarily of criteria such as perfor-mance, effectiveness, and efficiency). Particularly withrespect to the advantages of a real investment, it is im-portant that it is not emotional but rather rational criteriawhich are at the fore in the decision-making process.One of the key questions is whether there are limits totechnical progress, and where these limits might lie. As-sessment of technological possibilities with respect totheir benefits for patients requires an understanding ofmodern technology and its limits. Frequently, the aimof medical technological manufacturers and suppliersis to provide medical technological products and medi-cal data-processing systems which are better and moretechnically perfect every time. The result is that, thesedays, the functions of many medical technological prod-ucts go far beyond the needs and possible uses for them.Users – who are usually not technophiles – will pay forsomething extra that they cannot use. Numerous sophis-ticated products are perhaps technically perfect but arerarely tailored to suit a need. There is a lot which is fea-
sible technologically, but equally it is obvious that hu-mans can barely control this technology, as in the caseof the complexity of various software interfaces, whichare no longer completely understood even by highlyqualified technicians. This means that the technical pos-sibilities are frequently beyond the ability of many usersto use them. Uncritical enthusiasm for technology cantherefore very quickly turn into technophobia.
However, to do nothing or to make do without in-novations and to cling to outdated technical products isnot a solution either. In the future, the service providedto customers in hospitals or in a doctor’s practice willitself become a product with greater potential for dif-ferentiation than the quality and technical performanceof medical technological products. The innovations inmedical technology which will also be indispensable inthe future must have a human dimension and be tai-lored to suit a need. This will inevitably be embeddedin the area of tension between technical and scientificknowhow, market orientation, and orientation towardsindividual customers. From the point of view of theuser, virtually all products are becoming increasinglysimilar. Good customer service will be another factorin the success of medical products: the focus must in-creasingly be on the demand for products and not justsupplying them on offer.
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7
Medicine Is M2. Medicine Is More Than Applied Technologyfor Human Beings
Giovanni Maio
Medicine owes many of its undeniable achieve-
ments to technological developments; without the
elaboration of technologies, medicine would have
been unable to devise or apply many methods of
treatment which are, indisputably, a blessing for
mankind. And yet, curative science has sometimes
been dazzled by the alliance between medicine
and technology. Medicine has been taken in by
technology to such an extent that it has lost sight
of what characterizes it as curative science and
what constitutes its actual essence. Technology is
not just a method to be chosen, but also a pro-
gramme. Ethical reflections on the relationship
2.1 Technology Suggests Feasibilityand Controllability ................................ 7
2.2 Technology Knows No Bounds................ 8
2.3 Technology Is Unable to Answerthe Question of Meaning ....................... 9
2.4 Technology Alone Does Not Make MedicineHumane .............................................. 9
References .................................................. 10
between medicine and technology are presented
in this chapter.
From the very moment when medicine presentsa purely technical solution to the crisis of fallingill, medicine has not only chosen a method, buthas devoted itself to a certain view of the world
and humankind. If the relationship between medicineand technology is to be understood adequately, thesebasic preconceptions about humanity must be contem-plated.
2.1 Technology Suggests Feasibility and Controllability
Despite the uncertainty that still remains, a system thatbacks technology alone assumes a high degree of con-trollability of the system. In this case, that which isincalculable merely represents a challenge to the de-veloper to perfect technology to make it controllable.If technology is now used to heal the ill, and as a centralinstrument at that, this engineer’s way of thinking alsoinfiltrates how physicians think. In other words, physi-cians who rely fully on technology are under the tacitassumption that the problems faced by medicine aregenerally problems that can be solved using technology.If a problem remains, however, technology is to blamefor not being sophisticated enough, according to thiscredo. This way, it is assumed that basically everythingis feasible and that all problems faced by mankind canbe solved using technology. The reproductive-medicine
complex is one example of coupling treatment withtechnology. Reproductive medicine, in particular, whichincreasingly regards itself as a market-oriented ser-vice industry, equates remedy with the application oftechnical instruments; it responds to many persons’ cri-sis of meaning by offering technical solutions. Whatis more, reproductive medicine implicitly declares thetechnical solution to be the only possible responseto the challenge arising from involuntary childless-ness. Medicine that regards itself in this way does notonly create an offer, but also establishes standards thatthose who are confronted with involuntary childless-ness are virtually unable to avoid [2.1]. In particular,however, reproductive medicine comprehended in thisway fails to make use of the opportunity of mak-ing couples aware of the potential of alternative life
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concepts at a sufficiently early stage. Such an absolu-tization of the technical solution leads to a continuationof infertile couples being dependent on the techni-cal solutions offered by medicine, rather than makingthem aware that a crisis of meaning can also be over-come by giving life a new meaning, a meaning thatmay arise by opening up new prospects of life [2.2].It is the example of reproductive medicine, in par-ticular, that highlights the fact that humane medicineis more than about just being technically adept. Itis equally important to invest in good consultation,in a good conversation which should, in particularcases, also include touching upon the potential fail-ure of technology. Technology suggests feasibility –
as can be clearly seen using reproductive medicineas an example – and puts the victims of technologyin a situation where they are unable to escape fromthe resulting technical imperative. Thanks to technol-ogy, every woman has the opportunity to fall pregnant,and if they still remain infertile, they just have not in-vested enough or have not had a sufficient number ofattempts. It hardly occurs to the majority of physicians,nor, secondarily, to many couples, that the technicalsolution may not be the adequate one. Thus, technol-ogy creates a maelstrom, a feasibility maelstrom, whichcan only be resisted with difficulty. This aspect mustalways be taken into consideration with every newtechnology.
2.2 Technology Knows No Bounds
Technology has no boundaries; it progresses into un-chartered territory, it never shies away from the new,nor does it spare the essence of being; technology isalways oriented towards change and dynamism. Withsuch a basic concept, however, technology ensures thatthere is no longer such a thing as a reasonable bound-ary within medicine, and that there is no state that mightnot undergo technical optimization or change. Researchon embryos is one example of this. Here, in particu-lar, it can be seen that technical methods are consideredalmost blindly without thinking about morally tenableboundaries. There are grounds here for criticizing thebasic approach of using an inherently problematic tech-nical means for an undeniably good cause. The fact thatthe destruction of embryos was at all taken into accountas an option is the actual core of the ethical problem,which is that, in their basic approach, the natural sci-ences and technology grasp blindly at methods simplybecause they are technically feasible or simply becausethey are required to make promises come true. Offer-ing such options alone creates a problematic denial ofany boundaries whatsoever. It is like asking a counter-part a certain question that simply should not be asked,no matter what the situation is, because it is, for exam-ple, an unreasonable demand. In the same way, thereshould be certain methods in technical research and de-velopment that one simply does not select, because theyare bound to offend the feelings of far too many people,and should therefore be regarded as unacceptable. Con-sequently, the basic problem that research on embryoshas to face only arose because research methods werechosen blindly from the start, and, from the very begin-
ning, no respect was shown for the fact that merely therequest of sacrificing embryos is an unreasonable de-mand for many people – and this is just one examplerepresenting many more. We need only think of cloningtechniques, the creation of chimera, and so on. In thiscase, technicians cannot retract and deny any respon-sibility. Moreover, simply by selecting their methods,technicians assume responsibility, and this responsibil-ity must become apparent prior to the development sothat no blind mechanization occurs, but a mechaniza-tion on a humane scale. And this humane scale mustalso take boundaries into consideration, and must bearin mind that certain processes are inherently problem-atic. If they are still selected, despite being aware ofthese problems, presenting the whole of society witha fait accompli, this could signify a heavy burden incertain constellations.
And yet, it is not only the moral boundary that de-velopers of technology defy without further reflection –the denial of the boundary itself is the basic problem oftechnical development. Technology knows no point atwhich it could be said that it is perfect now as it is; tech-nology, i. e., those who work on technical products, arealways anxious to surpass existing technology with onethat is even faster, even more sophisticated, even smalleror even more comprehensive. This attitude towards end-less development is based on the lack of a notion aboutthe ideal state and on a glorification of efficiency. Thecredo is: the faster, the better; the more, the better, andso on. Admittedly, this credo may be useful when deal-ing with certain utensils. In the context of medicine,however, the credo cannot be generalized in all cases.
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Medicine Is More Than Applied Technology for Human Beings 2.4 Technology Alone Does Not Make Medicine Humane 9
What about the discussion on enhancement? This is pre-cisely where the esteem for more and more reaches itslimits and where less is more makes sense [2.3]. Thehuman being is not a machine that operates better thefaster it runs; humans need efficiency as much as theycrave leisure, they need to achieve their goals quickly,but also need changes in their lives, and resistance to be
able to mature at all. Accelerating everything – humanbeings included – does not automatically mean that hu-man beings are doing themselves a favor. With regard tohumanity, offering less, decelerating or back-pedallingis often more conducive to reaching the goal, provided,of course, that humanity finds fulfilment is the desirablegoal rather than rapid production.
2.3 Technology Is Unable to Answer the Question of Meaning
Technology knows only purpose-rational thinking, andif technology is proclaimed as the solution for mankind,the human being will primarily be regarded as a bodymachine within such thought. Technology does not askabout meaning, about the superior sense; indeed, it can-not ask what is meaningful, because it lacks the tools toassess the answer to this question – since the questionof meaning cannot be expressed in figures and values.With regard to technology in the context of medicine,this aspect is particularly precarious. As a result of tech-nology’s triumph, medicine has sometimes fallen victimto an absolutization of the natural sciences and technol-ogy, with the grave consequence that medicine is timeand again inclined to define not only what is properbut also what is good via the natural sciences. Thatwhich takes place as an applied natural science andtechnology in the course of the self-image of medicineis equating functionality with the good, equating naturalscientific properness with what is good for mankind. In
this context, organic functionality is occasionally seenas a value in itself; in other words, functionality shouldalways be restored. Secondly, the loss of functionalityis per se interpreted as something negative or even asa failure on the part of medicine under this natural scien-tific dictum. Both conclusions, however, are inherentlyproblematic. First of all, trying to restore functional-ity by all means may be problematic if sight of thewhole picture is lost. Concerning the superior sense,restoring functionality cannot be equated with the cre-ation of meaningfulness; for example, organs can berestored but the treatment may be senseless regardless.The more medicine becomes specialized and regards it-self as a natural science, the more it sometimes treatsorgans and x-ray photographs, blood gases, and labo-ratory values, but by doing this does not automaticallytreat the human being. Precisely this, then, becomesa serious problem if medicine sees itself only as a tech-nically oriented specialist medicine.
2.4 Technology Alone Does Not Make Medicine Humane
Bearing all this in mind, it should become apparent thatit is not a matter of demonizing technology. Technologyper se is not the problem of modern medicine. The prob-lem starts when the importance of technology is overes-timated, i. e., when it is assumed that existential ques-tions arising from a patient falling ill can only be solvedby technological means. The central criticism is there-fore not directed at technology itself, but at the thoughtthat technology is the one and only solution. Medicinethat categorically rejects technology is doomed to fail-ure, because in this case, it often fails to exploit thepotential of being able to assist. Medicine, however,that relies solely on technology and ignores everythingelse will equally fail. For this reason, humane medicinehas to focus on implementing technology, whilst al-
ways bearing in mind that human beings need morethan effective technology to recover. The art of heal-ing is to precisely recognize where technology wouldbe a good solution for human beings and where it ismerely an apparent solution. This art of healing requiresa pronounced practical power of judgement in a morecomprehensive sense, and not only technical expertise.
The technical credo in modern medicine overlooksthe fact that physicians often successfully bring abouta cure by a good relationship in which technology hasto be embedded. Technology without a relationship willgenerally achieve little. Great importance is attached tothe technical aspect, whereas the human relationship isoften completely ignored. This change in priorities rep-resents the greatest challenge mechanized medicine has
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to face. The more technology is used as a substitute fora relationship, the more this will lead to the loss of a cu-rative culture. Consequently, as long as we do not expectmore from technology than it is actually able to solve,and avoid using it as a substitute for everything, thesick will rightly hope that they will regain their health ifpossible or find comfort and meaning when there is nofurther chance of a cure. As long as medicine wishes tosee itself as a curative science and not as a repair ser-vice, it will have to invest the same amount of energy
in comforting the suffering and giving their life newmeaning as in technical development.
Further Reading• M. L. Eaton, D. Kennedy: Innovation in MedicalTechnology: Ethical Issues and Challenges (JohnsHopkins Univ. Press, Baltimore 2007)• R. Chadwick (Ed.): The Concise Encyclopedia ofthe Ethics of New Technologies (Academic, NewYork 2000)
References
2.1 G. Maio: Auf dem Weg zum Kind als erkauftes
Dienstleistungsprodukt? Eine ethische Kritik der
modernen Reproduktionsmedizin, Z. Evang. Ethik
52(3), 194–205 (2010)
2.2 G. Maio: Zur Hilflosigkeit der modernen Medizin im
Hinblick auf die Frage nach dem Sinn, Ethica 18(1),
3–9 (2010)
2.3 J. Boldt, G. Maio: Neuroenhancement. Vom tech-
nizistischen Missverständnis geistiger Leistungs-
fähigkeit. In: Das technisierte Gehirn. Neurotech-
nologien als Herausforderung für Ethik und Anthro-
pologie, ed. by O. Müller, J. Clausen, G. Maio (Mentis,
Paderborn 2009) pp. 381–395
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Hygiene in M3. Hygiene in Medical Technology
Heinz-Michael Just, Eckhard Roggenkamp, Annette Reinhardt
The application of new technologies in medicine
leads to therapeutic and diagnostic advance-
ments, yet also causes risks for patients to aquire
health-care associated infections. In this chapter
precautions to prevent the transmission of in-
fectious agents from inanimate medicotechnical
sources are shown.
Disinfection and sterilization processes are
described in detail aside with requirements for
cleaning equipement used for noninvasisve and
invasive technology on the patient (Sects. 3.4–3.7).
Targeted measures with focus on technical means
for preventing the four most important device-
related infections are pointed out in practical
examples (Sect. 3.8). Furthermore special atten-
tion is given to dialysis departments because of
high risk of infection both for patients and staff
and to the special processing of medical devices
that have been used on patients with proven or
strongly suspected Creutzfeld–Jacob disease (CJD)
respectively its new variant (vCJD).
Finally technical regulations and standards fo-
cused on german and european circumstances
give an overview of what must be observed
by manufacturers and users of medical devices
(Sect. 3.9).
3.1 Background ......................................... 123.1.1 Employee Protection ..................... 123.1.2 Patient Protection ........................ 12
3.2 Causes of Infection ............................... 13
3.3 Vaccinations......................................... 13
3.4 Disinfection Methods ............................ 143.4.1 Basics of Disinfection .................... 143.4.2 Disinfection Processes ................... 143.4.3 Chemical Disinfecting Agents ......... 153.4.4 Carrying out Manual Disinfection ... 153.4.5 Physical Disinfection Processes....... 163.4.6 Application Times
and Ranges of Action .................... 193.4.7 Comparison of Chemical
and Physical Disinfection Processes 20
3.5 Sterilization Methods ............................ 213.5.1 Sterilization Processes................... 21
3.6 Hygieneof Noninvasive Technology Equipment ... 253.6.1 Equipment Used on the Patient ..... 253.6.2 Equipment Not Used on the Patient 263.6.3 Repair and Maintenance ............... 26
3.7 Hygieneof Invasive Technology Equipment ......... 26
3.8 Practical Examples ................................ 263.8.1 Postoperative Wound Infections ..... 283.8.2 Ventilator-Associated Pneumonias
(VAP)........................................... 283.8.3 Catheter-Related Septicemia ......... 293.8.4 Catheter-Related Urinary Tract
Infection ..................................... 293.8.5 Dialysis ....................................... 293.8.6 Creutzfeldt–Jakob Disease ............. 31
3.9 Regulations ......................................... 313.9.1 Technical Regulations
for Hazardous Substances.............. 313.9.2 Standards ................................... 32
References .................................................. 33
Technology is increasingly finding its way intomedicine. Many diagnostic and therapeutic advance-
ments have only become possible as a result of corre-sponding technical processes and further developments.
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3.1 Background
The significance of hygiene becomes clear when werealize that even many years ago almost half of allinfections contracted by patients in hospital were asso-ciated with medicotechnical measures or were (partly)caused by them [3.1]. Medical progress uses increas-ingly complicated and sophisticated technical facilitiesand equipment, the use and preparation of which alsoendangers employees.
It is difficult to obtain reliable data which is moreor less representative from Germany, because to datethere is no central collection point for this purpose. Anindication can be gained by drawing on observationswhich are based on data from the Trade Associationfor Health and Welfare in Hamburg [3.2]. Accord-ing to these observations, infectious diseases representthe second largest group after dermatosis with a fre-quency of 7.3%, but their numbers increase to one-thirdin the case of those occupational diseases for whichcompensation is awarded for the first time. The datado not show what percentage of the cases of der-matosis can also be attributed to technical use inthe widest sense, such as handling of detergents anddisinfectants.
Hygiene measures in the context of medical tech-nology devices must therefore pursue the goals of
1. Protection of employees during handling,2. Protection of patients during use of these devices
against the transmission of germs, which can leadtoa) Contamination,b) Colonization, orc) Infection.
The measures that are necessary in individual casesto achieve these goals depend on several factors.
3.1.1 Employee Protection
When using these devices on patients, the rule is to actsuch that the risk of coming into contact with the pa-tient’s germs is kept to a minimum. This is achievedby providing appropriate briefing regarding correct han-dling before a medical technology device is used for thefirst time. Hygiene guidelines govern which protectivemeasures are necessary and when, but these protec-tive measures are also dependent on the illness of thepatient, the suspected bacterial colonization, and thepossible transmission path. When dealing with medical
technology devices in the course of reprocessing, main-tenance, and repair, the employee can himself monitorwhether the equipment is already visibly contaminatedon the outside or components are dirty, for example.He/she must in particular have been instructed by theoperator regarding whether the device has been usedimmediately beforehand for a patient with a contagiousdisease or with certain germs.
In such cases, disinfectant preliminary cleaningmust be carried out before maintenance or repair isbegun. Disinfection as a first step is also always nec-essary when handling of the device is linked withan increased risk of injury. Where reprocessing workis concerned, processes should be used in which thedevices are cleaned and disinfected by machine, andthis should be done with the application of heat andin one process. Under some circumstances, certainprotective clothing (e.g., gloves) is sensible or evencompulsory.
3.1.2 Patient Protection
How the medical technology device is used on thepatient is crucial to the necessary measures. A pace-maker implanted in the patient must be and remainsterile and pyrogen-free during insertion. Disinfectantpretreatment is sufficient for medical equipment withonly external (skin) contact, and in the case of equip-ment which stands at the bedside next to the patient,cleaning is generally sufficient. However, if parts ofa piece of equipment which is situated remotely fromthe patient come into contact with sterile areas of thepatient (e.g., tube systems which convey blood in a dial-ysis machine or in cardiac surgery equipment), then thissystem component must of course satisfy the same crite-ria as an implanted device. The same also applies whenequipment is used to introduce fluids or medication intosensitive (e.g., lungs in the case of machine-assisted ar-tificial respiration) or sterile regions of the body (e.g.,infusion apparatus) [3.3–5].
The text which follows explains the principles oftargeted hygiene measures and demonstrates, with ref-erence to examples, how the risks can be recognized andwhich risk-based measures are necessary. Reference ismade to sets of regulations which must be observed, al-though it is the duty of the person responsible for thearea in question to adapt the catalog of measures to newscientific findings and recommendations in the courseof regular training. General guidelines which are not
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Hygiene in Medical Technology 3.3 Vaccinations 13
orientated towards practical use, the specific risk of in-fection, and the path of infection are often expensive, as
they require a lot of personnel and time, but are rarelyeffective.
3.2 Causes of Infection
Requirements for an infection to develop are an in-fectious agent, a person susceptible to infection, andcontact which enables the germs to colonize the individ-ual such that an infection can develop. This multitudeof requirements makes it clear that there is no rea-son to live in general fear of microorganisms, bethey bacteria, viruses or fungi. Bacteria colonize ourskin and mucous membranes and are an importantpart of our body’s defenses. Over 40 different speciescan be isolated from our nasopharyngeal cavity, andthere are up to 1012 germs living in every gram offeces.
The natural bacterial colonization present in the skinof every human being can be divided into permanentand temporary. Permanent germs are always present,whereas temporary germs are acquired and thereforechange according to what the person has been handlingor what work he/she has been carrying out. Wash-ing the hands eliminates the majority (> 90%) of thisacquired contamination but leaves the permanent bac-terial colonization undisturbed. Disinfecting the handsor skin should completely eliminate acquired germs,but it also has an adverse effect on the permanent skincolony.
The skin and mucous membranes are mechanicalbarriers which, when they are not damaged, preventmicroorganisms from penetrating into our bodies. Thisexplains why damage to the skin and mucous mem-branes is always accompanied by an increased risk ofinfection, whether that be in the form of a local, super-ficial infection (pustule, abscess) or whether it be in the
form of a widespread infection – usually occurring inimmunocompromised patients – of the soft tissue (ul-ceration, gangrene), which can also result in sepsis withhigh fever.
In many fields, our body has also developed fur-ther defense mechanisms, such as the acid mantle ofthe skin, microorganism-killing enzymes in secretionsand excretions (e.g., tear fluid), and special structures inour blood whose primary role is to eliminate intruders.These include the white blood cells which eat up anddigest bacteria (phagocytose), and so-called antibodieswhich help blood cells identify structures in the bodywhich they should destroy. These specific antibodies areformed in the lymphatic tissue of our body followingsuch stimulation. Stimulation of this kind may be dueto contact with the infectious agent itself (natural immu-nization) or may be as a result of vaccination (artificialimmunization, see later).
If a germ nonetheless manages to attach to skin ormucous membranes, then the first important step hasbeen successful. If this colonization persists, althoughit does not result in illness, the patient or member ofstaff would become an (undetected) source of furthertransmission, in case the germ in question is a problem-atic germ (infectious agent, multiresistant bacterium).However, if in the second step the germ is able to de-ploy its pathogenic properties and the person affectedis not immune, then this would lead to an infectionwhich, depending on the state of health of the affectedindividual, can result in an illness which varies in itsseverity.
3.3 Vaccinations
One of the most important measures for protect-ing against infections is vaccination. The vaccinationswhich are recommended and constantly updated bythe Standing Committee on Vaccination (StändigeImpfkommission – STIKO) at the Robert Koch In-stitute (RKI) [3.6] are of particular importance foremployees in the health care system. The vaccina-tions in category S (standard vaccinations with general
application = standard vaccinations) are the vaccina-tions for infants and children and should be givento all employees in the health care system and, ifnecessary, should be regularly boosted. These includeimportant vaccinations against such as tetanus, po-liomyelitis, and diphtheria. Depending on the field ofactivity, so-called indicated vaccinations (category I)may also be added, such as vaccinations against hep-
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atitis A and B, influenza, and varicella. The point ofcontact for questions regarding personal vaccine pro-
tection and work-related requirements is generally theoccupational health officer.
3.4 Disinfection Methods
3.4.1 Basics of Disinfection
Like sterilization (Sect. 3.5), disinfection also has theaim of preventing transmission of pathogens. Completefreedom from germs (sterility) is not guaranteed, how-ever. Disinfection of equipment and materials is alwayssufficient if, although the aim is to prevent transmissionof microorganisms which are capable of multiplying,the body physiologically speaking has a certain level ofself-protection in these areas as well as in other areas ofthe human body which have colonies of germs (e.g., thegastrointestinal tract). Obligate pathogens (those whichalways cause illness) must not be present on disinfecteditems, however.
When using disinfectants and disinfection pro-cesses, both the respective microbiological spectrum ofactivity and the field of use must be taken into consid-eration. Thermal disinfection processes, where they canbe used, must always be given precedence over chem-ical disinfectants and disinfection processes. Providedthey do not contain any other special directions, chem-ical disinfectants are usually only suitable for killingvegetative bacteria and fungi.
Before they come onto the market, disinfectants aretested for their antimicrobial action by means of micro-biological analysis. There are standardized methods forthis, whose results also determine whether a substancewill be included in the list of substances permitted by
Table 3.1 Advantages and disadvantages and fields of use of the most common active substances in disinfectants
Active substance Advantages Disadvantages Field of use
Alcohols Fast-acting, no residues,low toxicity, pleasant odor
Not sporocidal,combustible/explosive, expensive
Hand disinfection,skin disinfection, small surfaces
Iodine/iodophosphoruscompounds
Does not irritate mucousmembranes, fast-acting
Allergies possible,naturally colored,(side-effects on thyroid?)
Skin disinfection,mucous membrane disinfection,hand disinfection
Formaldehyde/aldehyde Broad spectrum of activity,biodegradable
Irritant, allergenic,moderately toxic, (carcinogenic?)
Surfaces, instruments,disinfection of rooms
Quaternary ammoniumcompounds
Good detergent action,low odor, low toxicity
Gaps in effectiveness,inactivated by soap and protein
Disinfection of surfacesin special areas (kitchen)
Peracids/peroxides Broad spectrum of activity,fast-acting
Inactivated by protein,corrosive, irritant, unstable
Surfaces, instruments
Phenols Low impactbecause of environment
Gaps in effectiveness,barely biodegradable
Disinfection of excretions,otherwise obsolete
the Robert Koch Institute in accordance with the Ger-man Infection Protection Act [3.7].
3.4.2 Disinfection Processes
Thermal processes are only suitable for thermostableobjects, while chemical processes are also suitable forthermolabile objects and surfaces.
A distinction is made between the fields of use forchemical disinfection, as follows:
• Disinfection of hands, skin, and mucous membranes• Disinfection of surfaces• Disinfection of instruments.
Disinfection of Hands, Skin, and Mucous
Membranes and Disinfection of Surfaces
Disinfection of hands, skin, and mucous membranes anddisinfection of surfaces can only be carried out in theform of chemical disinfection, with various germicidalsubstance groups being used (Table 3.1). When select-ing a substance, the purpose for which it will be used andthe required strength of its effect as well as the requiredscope of its effect are crucial in this selection. Appro-priate definitions should be regulated in area-specificor process-specific hygiene plans based on the corre-sponding KRINKO (Kommission für Krankenhaushy-giene und Infektionsprävention) recommendation [3.8].
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Disinfection of Instruments
Instruments and equipment can be disinfected thermally,thermochemically, or else purely chemically. The choiceof the process is dependent on the suitability of thematerial for certain types of disinfection, on the localconditions (infrastructure), and if applicable, on certainrequirements. The most reliable option is mechanicalthermal disinfection in special washer-disinfectors, be-cause it is only when exposed to appropriate tempera-tures that the desired reduction in germs is guaranteedwith sufficient certainty. The machines report faults inthe program sequence, which means that it is not possi-ble to remove items inadvertently before the disinfectionprocess is complete, and errors are for the most partruled out. Purely chemical processes, such as immersionin solutions, etc., are in contrast susceptible to errors inprocessing and require a high degree of reliability on thepart of the staff performing the process.
3.4.3 Chemical Disinfecting Agents
The most common active substances in disinfectants,their advantages and disadvantages, and their fields ofuse are reproduced in Table 3.1. In the rarest cases,commercial disinfectants contain only one active sub-stance, but they frequently consist of mixtures of activesubstances in order to achieve the most optimum an-timicrobial action possible.
3.4.4 Carrying out Manual Disinfection
Selection of Disinfectants
Disinfectants are usually selected on the basis of theNetwork for Applied Hygiene (Verbund für angewandteHygiene, VAH) list. However, in so doing it is neces-sary to bear in mind that, in addition to the field of use,the concentration, and the application time (which aredependent on one another), the necessary scope of activ-ity is also ensured. Where there is any doubt, referencemust be made to appropriate expert advice. A furtherimportant source of information, in particular from thepoint of view of occupational health, is the materialsafety data sheets according to 91/155/EEC – amendedby 2001/58/EEC – for the disinfectants in question.With regard to material compatibility and effectiveness,particular care must be taken with materials which con-tain rubber and plastic.
Exposure Time
The maximum period during which the substance has itsintended effect can be gathered from the relevant data
sheets. If the solution becomes visibly dirty, however,then it should be replaced immediately. If a combina-tion of detergents and disinfectants is used, the exposuretime is generally only 24 h.
Sequence: Disinfection and Cleaning
In the case of instruments where there is a risk of in-jury, disinfection must be carried out prior to cleaning.In other cases, disinfection is performed with or aftercleaning.
Procedures
Disinfectants for treating surfaces and instruments areprovided by manufacturers in the form of a concen-trate in various packaging sizes, from sachets to largepacks, and must be made up to the appropriate us-age concentration by the user by adding water. Toavoid foam formation when preparing a disinfectant so-lution, water is added first and then the disinfectant.The solution is prepared by hand by means of dosingaids or using mixing equipment. The advantage of us-ing mixing equipment is the automatic dosing of thedisinfectant.
Disinfectants must only be used for the stated pur-pose and must not be mixed with detergents withoutprior testing, because this can result in a loss of effec-tiveness of the disinfectant (follow the information fromthe manufacturer). It becomes necessary to change thedisinfectant solution when the exposure time stated bythe manufacturer has been reached or when the solutionbecomes visibly dirty.
Effectiveness may be impaired in tubes and pipeswith narrow lumen, e.g., as a result of air bubbles or im-purities. It is therefore necessary to ensure that the itemto be disinfected is completely submerged, that thereare no bubbles, and that all surfaces are completely andthoroughly wetted.
All items should be disassembled as far as possible.Instruments should be immersed in the solution withcare to prevent damage.
Cost-Saving Hints
The following options can be used for cost savings:
• It is often sufficient to carry out cleaning instead ofdisinfection prior to subsequent sterilization. Excep-tions: Only pointed, sharp items must be disinfectedprior to cleaning.• Where feasible from a time perspective, low con-centrations should be selected with a longer appli-cation time.
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• If possible, make do without additional detergents,because a disinfectant solution with added detergentmust be changed daily.• Contaminate the solution as little as possible withorganic materials, so that it is not necessary tochange the solution before the end of the exposuretime.• Wipe down items instead of immersing them.
Pouring Away
To protect drainage systems against corrosion, caremust be taken to ensure that the solution is dilutedsufficiently before it is poured away. Disinfectants fortreating instruments are generally provided with cor-rosion inhibitors. High concentrations can neverthelessbe problematic for drains. The municipal wastewaterbylaws must also be taken into account. Disinfectantconcentrates are considered hazardous substances, andtheir disposal requires special supervision.
Personal Protection
When preparing the solution, immersing/removingitems, and emptying and cleaning the bowl, gloves (dis-posable or household gloves) and protective clothing(waterproof apron) must be worn. If there is a dan-ger of splashing, protective goggles and a face maskmust be worn. Bowls filled with disinfectant must becovered to minimize evaporation into the surround-ing air. Disinfectant solutions must always be madeup with cold water (no warmer than lukewarm) forthe same reason. Disinfectant concentrates must notbe stored above eye level. The workplace-specificregulations to protect staff should take into accountthe relevant technical regulations (the German Tech-nical Regulations for Biological Agents, TRBA, andthe Technical Regulations for Hazardous Substances,TRGS) (Bundesanstalt für Arbeitsschutz und Arbeits-medizin, BAuA).
Special Circumstances
There may be undesired effects on materials if unsuit-able disinfectants are used. The chemical resistance ofthe items must therefore always be taken into account.Where there is any doubt, enquiries should be made tothe instrument manufacturer.
3.4.5 Physical Disinfection Processes
With physical disinfection processes, a distinction ismade between thermal and thermochemical disinfectionprocesses.
Thermal Disinfection Processes
In thermal disinfection processes, pathogens are ren-dered harmless as a result of the influence of heat.The higher the temperature and the longer the applica-tion time, the more effective the process is. In practicalapplications, a distinction is made between dry heatand damp heat, depending on the presence or absenceof free water. Only damp heat is of significance forcombating hospital infections. When using a treatmentwith damp heat, a distinction is made between twoprocesses:
1. Rinsing with hot water (washer-disinfectors) and2. Treating with steam (steam disinfection process).
Washer-disinfectors
Washer-disinfectors are devices in which instruments,anesthesia accessories, laboratory materials (glasswareand the like), and other thermostable items are pro-cessed by machine.
The series of standards DIN EN ISO 15883 specifiesthe performance and device requirements for washer-disinfectors.
Depending on the design, a distinction is made be-tween washer-disinfectors with one processing chamberand devices with multiple processing chambers, so-called batch washer systems.
Washer-disinfectors are available in a front-loadingdesign (loaded and unloaded in the same area) or ina through-loading design with two doors (separated intoa clean and dirty side).
Batch washer systems (multichamber systems) con-sist of multiple washing chambers and drying chambersthrough which the items to be treated are passed onloading trolleys. The loading trolleys differ accordingto the items to be treated. Sensors on the loading trol-leys allow the control unit in the system to identify whatitems are on the trolley and to automatically select thecorrect processing program, which means that operat-ing errors as a result of incorrectly selected programs,temperatures, and times are ruled out.
The disinfection process which runs in each caseis usually thermochemical or thermal. An ultrasoniccleaning tank can be added to the system as an addi-tional feature for precleaning of heavily soiled items.
Different processing steps are performed in eachchamber. Special tanks with the appropriate detergentsare assigned to each chamber. The detergent solution iscollected in the tanks and reused for the next process-ing batch. Because not all of the detergent solution isrecaptured, some of the solution must be supplemented.
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The exact dosing of the detergent is done using dosingpumps which are controlled via contact water meters.The contents of the processing tank must be emptiedand refilled every working day.
Owing to their relatively high throughput rate, batchwasher systems are predominantly used in central sterilesupply departments.
Carrying out Machine Cleaning
and Disinfection
To achieve a good cleaning and disinfection result,the way in which the machine is loaded is of cru-cial importance. It is important to ensure that all itemsare disassembled as far as is possible and that hollowparts are inserted with the opening pointing downwards.Fluid must also flow through the interior of instrumentswith long or narrow cavities, such as metal catheters,metal suction apparatus, special needles, etc. Specialloading trolleys must be used for this.
In the case of use of detergents or combined dis-infectants and detergents, the information provided bythe manufacturer (application time, concentration, andtemperature) must be followed precisely.
Only the correct dosage will ensure a perfect disin-fection and cleaning result while providing the greatestpossible protection of the material. Underdosing of al-kaline detergents involves the risk that pitting mayoccur, as this is avoided at pH values of above 10.5.When using acidic detergents, corrosion may occur asa result of chlorides in the water, and this can only beprecluded by using demineralized water.
In the case of machine cleaning, all residues fromthe cleaning phase must be reliably removed in the rins-ing phase, as otherwise stains and discolorations mayappear on the surgical instruments. Additional use ofa suitable neutralizing agent can support this processand improve the result of rinsing.
Documentation
In the course of quality assurance, when processingmedical equipment it is necessary for the process-relevant processing steps of the individual batches to bedocumented with direct assignment to the relevant itemsto be treated.
Inspections and Maintenance
Disinfection measures in cleaning equipment are onlyeffective if maintenance and inspection of these ma-chines are not neglected. The necessary inspection andmaintenance are specified in the operating instruction,which should be issued by the manufacturer. Mainte-
nance should be carried out at least once a year bytrained specialists.
Tests
The ordinance regarding the installation, opera-tion, and use of medical devices (German Medi-cal Devices Operator Ordinance – Medizinprodukte-Betreiberverordnung, MPBetreibV) states the require-ment that medical devices must be processed usingsuitable, validated processes such that reproduciblesuccess is ensured and the safety and health of pa-tients, users, and third parties are not endangered. TheKRINKO recommendation [3.9] likewise requires vali-dated processing of medical devices.
Specific information about carrying out the vali-dation and the subsequent periodic tests is set out inDIN EN ISO 15883-1 – Washer-disinfectors – GeneralRequirements, Definitions, and Tests, and in the guide-line from the German Society for Hospital Hygiene, theGerman Society for Sterile Supply, and the WorkingGroup Instrument Preparation for routine monitoring ofmachine washer-disinfectors for thermolabile medicaldevices.
Validation is a documented process for providing,recording, and interpreting the results necessary to showthat a process constantly produces the desired qual-ity which conforms with the given specifications. Forwasher-disinfectors (WD), the validation consists ofinstallation qualification, operating qualification, andperformance qualification, performed for devices whichhave documented proof from the manufacturer of com-pliance with the requirements of DIN EN ISO 15883.
The installation qualification is performed to en-sure that the WD and accessories have been properlysupplied and installed and that the supply of operatingmedia satisfies the special requirements. The tests andinspections which are to be carried out for the installa-tion qualification must be defined and performed, andthe results documented.
Tests and inspections which must be carried out are:
• Testing the scope of supply and delivery (in the caseof existing installations, testing the stock)• Loading trolleys/baskets, cartridges, and also plugs/adapters• Installation plan, instructions for use• Testing the connections and supply of media, andcomparing them with the installation plan• Electricity• Water (cold/warm/demineralized)• Steam
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• Wastewater• Exhaust air/ventilation.
The operating qualification is carried out to en-sure that the WD and the supply of media complywith the manufacturer’s specifications and the require-ments set out in DIN EN ISO 15883. The tests andinspections which are to be carried out for the operat-ing qualification must be defined and performed, andthe results documented. In the performance testing, thespecified washer-disinfector programs are tested for ref-erence loading, and the results are documented. Whenobserving the regulations, it should be ensured that re-sults are obtained which can be reproduced at any time.Any reference loading must cover instruments with con-tamination which is typical of operation as well ascritical design features. Reference loading is alwaysoperator specific and must be documented. A require-ment for the performance qualification is specificationand documentation of the necessary programs with thecorresponding process flows. The description of the pro-cess must also include the preconditions for cleaning.The process description must be documented in detail,including precise information about the chemicals. Thefollowing tests are performed as part of the performancequalification.
Testing the Cleaning. The cleaning is tested usingtwo different methods. Test instruments (hemostats af-ter Crile) with defined test soiling in accordance withDIN EN ISO 15883 and instruments which are actu-ally soiled following use are used. Every program usedmust be tested. The test instruments are removed fromthe WD using gloves following the cleaning phase andprior to the disinfection phase.
The results of the cleaning process are first evalu-ated visually, and these findings are documented. Thetest instruments must be visibly clean. The test instru-ments must then be tested for protein residues usinga protein detection method which is at least semiquan-titative. In practice, detection of protein residues usingthe Biuret method has proven successful. Testing of theinstruments which are actually soiled is carried out inthe same way.
Assessment. The limit value is that all test instrumentsmust neither reach nor exceed the protein content of100 μg protein per ml eluate. If this limit is exceeded,then the WD is immediately shut down. The guide valueis a maximum of 50 μg protein per ml eluate for a testinstrument, at which no measures are necessary.
Testing the Disinfection. The disinfection is testedusing thermoelements which are distributed in the dis-infection chamber at critical locations and which recordthe temperature profile during processing. The result-ing temperature graphs show whether the temperaturenecessary for killing microorganisms was present at alllocations in the chamber. The A0 value can be calcu-lated from the temperature graph in accordance withDIN EN ISO 15883. The A0 value of a disinfection pro-cess with damp heat is a measure of the rate at whichmicroorganisms are killed, given as a time in seconds ata temperature of 80 ◦C applied to the medical item bythe process.
The A0 value which must be achieved depends onthe nature and quantity of the microorganisms on thecontaminated medical device and on the subsequentuse. In the case of crucial medical devices and medicaldevices which are or may be contaminated with heat-resistant viruses such as hepatitis B, the A0 value mustreach 3000. This corresponds to an application time of5 min at a temperature of 90 ◦C or an application timeof 50 min at a temperature of 80 ◦C.
An A0 value of 600 is used in the case of noncriti-cal medical devices which can only come into contactwith undamaged skin. This corresponds to an appli-cation time of 1 min at a temperature of 90 ◦C or anapplication time of 10 min at a temperature of 80 ◦C.
In addition to the thermoelectric measurements (A0concept), biological indicators can also be used to makestatements about the killing of microorganisms. Biolog-ical indicators are germ carriers which are contaminatedwith a blood/germ mixture which has a defined resis-tance to the disinfection process in question. The RobertKoch Institute stipulates the use of contaminated screwsand tubes for testing thermal disinfection processes inwasher-disinfector machines. Meanwhile, equally goodbiological indicators are available which allow testingwhich is easier for the user.
The performance qualification must be repeated an-nually. When the programs or process chemicals arechanged or new medical devices are introduced whichhave to be processed differently, the performance quali-fication must be carried out once more.
Decontamination Systems
Decontamination systems have in the past been usedfirst and foremost for cleaning and disinfection (de-contamination) of bed frames and accessories. Require-ments regarding hygiene, economic considerations, andoccupational safety requirements (TRBA 401 hazarddue to skin contact) have led to decontamination sys-
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tems increasingly being used for other articles in thefield of medicine as well, such as transport trolleys, con-tainers (e.g., for medications, medical devices, sterilearticles, and meals), operating theater shoes, transport-ing containers for small conveyor systems, and similaritems.
A decontamination system consists of a decontami-nation chamber, which receives the items to be treated,and an apparatus compartment, which contains the unitsand components necessary for operation. The systemsare generally constructed with a two-door design.
The items to be treated are pushed into the decon-tamination chamber on the dirty side (in some casesusing special loading trolleys). Combined cleaning anddisinfection of the items to be treated is carried outin the first phase using a separate nozzle system bymeans of a recirculation pump. The temperature ofthe decontamination agent solution and the decontam-ination period can be set and changed on the controlpanel, making it possible to optimally adapt the processquickly and simply to the items being treated. The de-contamination agent solution is supplied from a heatedstorage tank.
Following the decontamination process, the itemsbeing treated are sprayed with a rinsing agent solution toremove residues of the decontamination agent solutionand ensure fast and spotless drying. During the dry-ing time, a ventilator extracts the damp warm air fromthe interior of the compartment, while at the same timesucking in fresh air from the clean side. The decontam-ination agent solution is pumped back into the storagetank via a recirculation pump, so that only about 20 l ofwater is required for each batch.
With regard to the requirements, operation, and test-ing of the effectiveness of decontamination systems,reference should also be made to DIN standards 58955section 1–7.
Steam Disinfection Processes
Steam disinfection processes are preferably used to dis-infect bedding (mattresses, laundry, and textiles) butalso for waste which needs to be disinfected. Simul-taneous use of these systems for disinfecting waste aswell can be considered to be problematic because of theoffensive smell and risk of contamination of the appa-ratus. With appropriate separation, however, joint use ofthe apparatus to disinfect both bedding and waste is alsoperfectly feasible.
The items to be disinfected are subjected to theeffect of saturated steam in the steam disinfection ap-paratus. To ensure that all surfaces to be disinfected
are exposed to unobstructed steam, the air must beremoved from the disinfection chamber and from theitems.
A distinction of steam disinfection processes can bemade depending on the procedure:
1. Steam flow process, and2. Fractionated vacuum process (vacuum–steam–va-
cuum (VSV) process).
Steam Flow Process (Range of Action, ABC:
Sect. 3.4.6). In the steam flow process the air is forcedout of the chamber and the items to be disinfectedusing saturated steam. The disinfection temperature is100–105 ◦C, with an application time of at least 15 min.For porous items, the application time may be more than1 h. The steam flow process is suitable for disinfectingwaste which contains sufficient water, e.g., microbio-logical cultures.
Fractionated Vacuum Process. The process (Fig. 3.1)is characterized by:
1. Removal of the air from the chamber and the itemsto be disinfected by repeated evacuation alternatedwith influx of saturated steam
2. Disinfection with saturated steam3. Drying of the disinfected items by evacuation.
To perform this process, steam which is largelyfree of air and foreign gases is necessary (cf. DIN EN285). The disinfection chamber must be vacuumtight.The fractionated vacuum process is mainly used to dis-infect porous items such as mattresses, blankets, andwaste.
3.4.6 Application Timesand Ranges of Action
The application times and ranges of action are presentedin Table 3.2. In the list of disinfectants and disinfectionprocesses tested and approved by the Robert Koch Insti-tute [3.7], the ranges of action are identified by letters;these are:
• A – suitable for killing vegetative bacteria, includ-ing mycobacteria, as well as fungi, including fungalspores• B – suitable for inactivating viruses• C – suitable for killing spores of the anthraxpathogen.
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p/T
Forevacuum Disinfection Drying Venting
t
Fig. 3.1 Diagram of the fractionatedvacuum process
Table 3.2 Application times and ranges of action of disinfection processes
Temperature (◦C) Duration (min) Range of action
75 20 A, B (except viral hepatitis)
105 1 A, B
105 5 A, B, C
Higher temperatures and longer application timesare sometimes used for disinfecting waste. Approvedprocesses can be found in the RKI list. The require-ments, operation, and testing of the effectiveness ofsteam disinfection apparatus are laid down in the DINstandards 58949 section 1–7.
3.4.7 Comparison of Chemicaland Physical Disinfection Processes
Disadvantages of Chemical Disinfection• Gaps in effectiveness, contamination• (Primary) bacterial resistance• Adaptation (biofilm formation)• Possible distribution of germs in the hospital (cen-tral units)• Dependence on concentration, temperature, andpH• Decomposability, loss of effectiveness
• Inactivation by soap and protein• Limited ability to penetrate organic material• Risk of decontamination• Disinfectant residues in the material (e.g., rubber)• Material corrosion• Health effects for staff and patients• Pollution of the workplace and environmental dam-age• High costs• Increase in the volume of refuse.
Advantages of Physical Disinfection Processes• Lower costs• Lower impact on the environment• Higher degree of reliability• Automated operation possible• Cleaning, disinfection, and drying in one process• No toxicity and no allergization• Testing for effectiveness.Part
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Hygiene in Medical Technology 3.5 Sterilization Methods 21
3.5 Sterilization Methods
3.5.1 Sterilization Processes
• Physical processes• Steam sterilization• Hot air sterilization• Physicochemical processes• Ethylene oxide gas sterilization• Formaldehyde gas sterilization• H2O2 low-temperature plasma sterilization.
Physical Processes
Steam Sterilization. Sterilization with the aid of sat-urated and compressed steam, also sometimes referredto as damp heat, is the most reliable sterilization pro-cess and, because of its simple handling, is the mostimportant process for sterilizing medical devices.
The principle of steam sterilization is based on thetransfer of thermal energy to the contaminated surfacesas a result of condensation of compressed steam. Energyis released through condensation of the steam on theitems to be sterilized, which causes irreversible damageto microorganisms.
The pressure and temperature of steam are depen-dent on one another; for example, compressed, saturatedsteam at a temperature of 121 ◦C has a pressure of 2 bar(1 bar = 105 Pa), while at a temperature of 134 ◦C it hasa pressure of 3.2 bar. In practice, two standard condi-tions are used:
• 121 ◦C with application time of 15 min• 134 ◦C with application time of 3 min (only for cor-respondingly heat-resistant items).
Pathogen Resistance to Damp Heat. The resistanceof germs to damp heat is classified into four levels (Ta-ble 3.3).
A complete effect of the steam on the items to besterilized is only possible if the air has been removedfrom the chamber and from the items which are to besterilized. Processes for removing the air from the itemsto be sterilized include:
Table 3.3 The four levels of resistance of germs to damp heat
Level of resistance Temperature (◦C) Application time Pathogens recorded
I 100 Seconds to minutes Vegetative bacteria, fungi including fungal spores, viruses, protozoa
II 105 5 min Bacterial spores with a lower level of resistance, e.g., anthrax spores
III 121 or 134 15 min or 3 min Bacterial spores with a higher level of resistance
IV 134 Up to 6 h Bacterial spores with a high level of resistance
1. Fore-vacuum process. In the fore-vacuum process(Fig. 3.2), the air is removed from the sterilizerchamber using a vacuum pump. The process fea-tures the following operating phases:– Single evacuation of the sterilizer chamber to
pressure of 20–70 mbar– Admission of steam until the operating pressure
has been reached.The fore-vacuum process is not suitable for ster-ilizing porous items (e.g., laundry) in sterilizationcontainers with a filter or valve in the lid of thesterilization container.
2. Fractionated vacuum process. The fractionated vac-uum process (Fig. 3.3) features operating phasessuch as:– Evacuation to pressure < 130 mbar (1 mbar
= 100 Pa), repeated several times– Alternated with influx of steam to a pressure
which is below or above atmospheric pressure– Admission of steam until the operating pressure
has been reached.
The fractionated vacuum process is suitable for allsterilization items in packaging approved for steam ster-ilization.
According to the German Medical Devices OperatorOrdinance § 4, medical devices must be sterilized us-
p
t
Fig. 3.2 Fore-vacuum process
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p
t
Fig. 3.3 Fractionated vacuum process
ing suitable, validated processes, such that reproduciblesuccess of these processes is ensured and the safety andhealth of patients, users, and third parties are not en-dangered. Validation serves to prove the effectiveness ofthe sterilization process under the operating conditionspresent in the location where the equipment is installed,with the items which are to be sterilized in routineoperation, in the appropriate packaging, and with theloading model used. Validation consists of commis-sioning and performance qualification. DIN EN 554and DIN 58946-6 have been replaced by DIN EN ISO17665-1. Validation according to DIN EN ISO 17665-1consists of installation qualification (IQ), operationalqualification (OQ), and performance qualification (PQ).
In the installation qualification, evidence must befound that the device equipment, documentation, oper-ating media, and installation comply with the standard.It must also be demonstrated that the device is in goodworking order, and that there is no leakage of the oper-ating media or in the equipment.
In the operational qualification, evidence must beprovided that the sterilizer is able to perform the speci-fied sterilization programs.
In the performance qualification, all sterilizationitems and the types of packaging used must be recordedand commissioned. The sterilization parameters of theresulting commissioned items are then measured andassessed in the sterilizer using physical test methods.
In addition to the physical test methods, DINEN ISO 17665 also approves microbiological testing.Thermoelectric tests cannot be performed on medi-cal devices (e.g., instruments for minimally invasivesurgery). In this case, there is the option of contami-nating the instrument directly with test germs or usingsuitable medical device simulators as per DIN 58921.The results must be documented in the validation report.
Documentation. As part of the quality assurance inthe central sterilization supply department (CSSD), thesterilization batches must be documented. This is donefirstly by recording the process-relevant sterilization pa-rameters (pressure, temperature, and time) and secondlyby testing each batch using a suitable chemical indicatorin a special test specimen. Using a label with the batchnumber on ensures that the item to be sterilized is as-signed to the batch. Once sterilization has taken place,the parameters are checked, and the batch is releasedand documented.
Hot Air Sterilization. Hot air sterilization is sterilizationby dry heat. Because dry air is a poor thermal conductor,relatively high temperatures and long application times(e.g., 180 ◦C for 30 min sterilization time) are neces-sary to ensure reliable sterilization. Table 3.4 presentsthe sterilization times for hot air sterilization.
Germs, spores, and viruses are killed as a result ofprotein coagulation. The sterilization effect is stronglydependent on the preparation of the items to be steril-ized. The items to be sterilized must be clean and dry(evaporatively cooled).
The following must be taken into considerationwhen loading the sterilizer.
• It must be possible for air to flow unhindered aroundall of the items.• The direction of the air flow must be taken intoaccount.• Larger items can create a slipstream.• The items to be sterilized must not be stacked inblocks.
Larger sterilizers must be equipped with forced aircirculation equipment (ventilator). Because of their un-reliable operation, hot air sterilizers should only be usedto a very limited degree. Their fields of use are:
• Glass (laboratory)• Metal• Porcelain.
Suitable packaging materials are:
• Metal cases• Glass bowls• Aluminium foil.
Note that textile and paper packaging are not suitable.
Physicochemical Processes
Ethylene Oxide Sterilization. Sterilization with ethy-lene oxide must only be used if the item to be sterilizedcannot be sterilized using any other process [3.10].
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Hygiene in Medical Technology 3.5 Sterilization Methods 23
Table 3.4 Sterilization times for hot air sterilization
Sterilization temperature (◦C) Sterilization time (min)
160 120
170 60
180 30
According to the German Ordinance on HazardousSubstances and the TRGS 513, since 1 January 1995,ethylene oxide (EO) may only be used in validated, fullyautomatic sterilizers, in which an automated degassingprogram follows the sterilization program, with the ster-ilizer remaining locked until the program is finished.
Substance Properties. Ethylene oxide is a colorless,sweet-smelling, highly flammable gas, which can formexplosive mixtures with air. It is toxic and can causecancer and inheritable damage. A maximum allowableconcentration (MAC value), in the sense of harmlessconcentration, can therefore not be given. The technicalreference concentration (TRC value) for the breathingair in the workplace is 1 ppm-vol. EO irritates the eyes,the respiratory organs, and the skin. It is classified ashazardous to water (water hazard class WHC 2).
How It Works. Its good ability to penetrate cells makesit possible for various vital biochemical components inthe metabolism of microorganisms, such as DNA, pro-teins, vitamins, and enzymes, to be exposed to EO.The alkylation reaction of proteins with EO kills themicroorganisms.
The effectiveness of EO is influenced by various pa-rameters. The relative humidity of the gas mixture isoptimally 33% at a temperature of 55±3 ◦C. Becausethe materials to be sterilized and their packaging absorbwater to different degrees depending on how the steril-ization chamber is loaded, relative humidity of 100% isin practice aimed for at the beginning of the sterilizationprocess. Water loss due to vacuum and absorption thenresults in a reduction in the relative humidity. This ini-tially high humidification should in practice prevent therelative humidity from dropping below the limit valueof 33% which is necessary for reliable EO sterilization.
Adsorption and Desorption. Ethylene oxide bindsto surfaces of solids (is adsorbed) depending on thematerial. With regard to EO sterilization this meansthat residues adhere to the materials following EOexposure. A relatively long degassing or desorptiontime is therefore necessary for the treated items fol-lowing sterilization. These may contain a maximum
residual concentration of 1 ppm EO before use onpatients [3.11]. As already mentioned above, in accor-dance with TRGS 513, the desorption process mustbe performed in the sterilization chamber, which isautomatically locked, after sterilization has ended.Reloading of the sterile items directly after sterilizationinto so-called ventilation cabinets is not permitted.
Exhaust Air from EO Sterilization Systems. A mass flowof 2.5 ppm EO (according to the German Technical In-structions on Air Quality Control, TALuft) must not beexceeded in the exhaust air from the system. Methodsused for reducing the EO concentration are listed here.
• Combustion. This must be supported using aux-iliary gas firing. The consumption of fuel gas is≈ 0.5 m3/h. In the process, EO is fully convertedinto carbon dioxide and water.• Catalytic reaction. The necessary temperature of thecatalyst is reached by supplying energy in the formof steam or electrical energy. It is virtually impossi-ble to achieve complete decomposition of the EO.• Gas wet scrubbing process (only for pure EO). Thefirm VIG provides a process in which the EO isbonded with a washing agent. Using diluted sulfuricacid in water, the EO is converted to ethylene gly-col. The EO is disposed of completely, and there isno need to supply exhaust air.
Sterilization Processes
Vacuum Process. This process involves working with100% EO in the vacuum range. After evacuation to be-low absolute pressure of 55 hPa and humidification ofthe sterilization chamber, the EO flows into the cham-ber, and the items to be sterilized are treated at anoperating temperature of 50–60 ◦C for between 1 h and6 h. The application time is essentially determined bythe process parameters of EO concentration, pressure,humidity, and temperature. The pressure range is keptbelow the lower explosive limit of EO. The sterilizationchamber is then purged and ventilated multiple times.
Overpressure Process. Following a pre-vacuum andhumidification, sterilization is performed in the over-pressure range using a gas mixture of 6% EO and 94%CO2. As in the vacuum pressure process, the applicationtime is essentially determined by the process parametersof EO concentration, pressure, humidity, and temper-ature. The inert gas (mostly carbon dioxide) helps toavoid explosion. After the sterilization phase, multiplevacuum and ventilation phases take place alternately to
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achieve desorption of the EO from the sterile items. Thedesorption time is generally 8–10 h.
Requirements for Sterilizers. The requirements for re-liable sterilization are described in detail in DIN 58948and DIN EN 1422. According to the German ordinancefor minimizing hazardous substances, care should betaken to ensure that sterilizers work with gas mixturesof 6% EO and 94% CO2 and that the risks for staff,patients, and the environment are therefore reduced.
Requirements for Operating Staff. According toTRGS 513, operating staff must demonstrate knowl-edge of the subject through an approved course.
Formaldehyde Gas Sterilization
Substance Properties. Formaldehyde (FO) is a color-less, pungent-smelling gas with a broad spectrum ofbiocidal activity. It is toxic, allergenic, suspected tocause cancer, combustible, and can form explosive mix-tures with air. With the exception of its allergenicity, thepotential for danger in the areas just mentioned is lowerthan in the case of ethylene oxide, but it is also less ef-fective. The maximum allowable concentration (MACvalue) is 0.5 ppm. Formaldehyde is commercially avail-able as a 30–50 weight percent solution (formalin).
Adsorption and Desorption. Formaldehyde is adsorbedby the surfaces of solids. With regard to FO sterilization,this means that residues remain on materials follow-ing FO exposure. After the sterilization phase, the FOresidues adsorbed on the sterile items are removed bypurging with air and steam (desorption). The extent ofadsorption and desorption is dependent, among otherthings, on the type of material of the solids. Experi-ments looking at its desorption behavior have shownthat the residues on sterilized products can often beremoved relatively easily, but that the residues in thesterilization packaging are many times higher in com-parison. FO-sterilized items stored in poorly ventilatedspaces can lead to the MAC value for formaldehyde be-ing reached in the air of the room. Storage locationsin which sufficient dilution and aeration are guaranteedmust accordingly be selected.
Process Sequence
1. Ventilation and humidification, often using a frac-tionated vacuum process. The FO sterilizationprocess is not able to penetrate to the same extentas the EO sterilization process. To achieve sufficientpenetration in the process, the FO sterilization pro-
cess may only be performed using the fractionatedvacuum process.
2. Sterilization, at a constant, low vacuum and highatmospheric humidity (at least 60%); i. e., formalde-hyde and steam are used for sterilization in combi-nation at temperature of 60–75 ◦C.
3. Desorption: purging and ventilation using steam/airscrubbing; i. e., the chamber and the items beingsterilized are purged in 15–20 changes in pressurewith air or steam.
Requirements for Sterilizers. Sterilizers must complywith the requirements of DIN 58948.
Requirements for Operating Staff. According toTRGS 513, operating staff must demonstrate knowl-edge of the subject through an approved course.
H2O2 Low-Temperature
Plasma Sterilization (LTP)
Field of Use. Because of their well-known problems inrespect of residues, there are considerable restrictionson operation of conventional gas sterilizers (ethyleneoxide/formaldehyde) (German Ordinance on HazardousSubstances, TRGS 525). No harmful residues of theactive substance are to be expected in the case ofH2O2 LTP sterilization, which is based on the activesubstance H2O2, i. e., hydrogen peroxide plasma, andwhose chamber temperature is 45 ◦C.
Active Principle. The active substance used is hydro-gen peroxide (H2O2). In a vacuum it is evaporated,diffused through the sterilization packaging, and thenexcited by radiofrequency to form hydrogen peroxideplasma. Hydroxyl and hydroperoxy radicals form in theplasma, which inactivate the microorganisms. After theradiofrequency field is switched off, the radicals losetheir high levels of energy and recombine to form waterand oxygen [3.12, 13].
Process Sequence
First Phase: Vacuum. The sterilization chamber isevacuated to residual pressure of ≈ 1 mbar (1 mbar =100 Pa). The radiofrequency generator is then switchedon, and an air plasma is generated. The chamber is thenventilated and evacuated once more to prepare for theinjection. The air plasma allows any residual moistureto be dried for better preparation for loading.
Second Phase: Injection. At room temperature, 1.8 mlH2O2 is injected into the chamber and evaporated at
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pressure of ≈ 11 mbar. A short period of ventilationthen follows. This ensures that the active substance pen-etrates quickly into the lumina.
Third Phase: Diffusion. The H2O2 diffuses into theitems being sterilized. A vacuum is generated onceagain before the plasma phase.
Fourth Phase: Plasma. The pressure in the chamberis reduced to 0.7 mbar, and the plasma phase is be-gun by means of radiofrequency in the MHz range.The hydrogen peroxide vapor is thereby ionized, i. e.,converted into gas plasma. This consists, among otherthings, of highly reactive hydroxy and hydroxyl rad-icals, which bond with functional building blocks ofmicroorganisms, thus causing them irreversible dam-age. Phases 2–4 are carried out twice, the so-called firstand second halves of the cycle.
Fifth Phase: Ventilation/Pressure Equalizing. Follow-ing completion of the 10 min plasma phase, the gasresidues in the chamber and in the sterile items are re-moved harmlessly by fractionated air purging and activecarbon filtering. The vacuum is equalized. When atmo-spheric pressure is reached, the cycle is ended and thedoor can be opened.
Process Duration. When fully loaded, the process lastsfor 75 min. Smaller loads sometimes mean shorter pro-cess times.
Information for Use. Because of the way in whichit works, this process can be used for sterilization of
thermolabile items, but with certain restrictions [3.14].Users of this process should draw up a list of all thethermolabile items which must be sterilized and thendecide which items this process can be used for. A so-called positive list of articles which are approved forsterilization is issued by the manufacturer.
Based on comprehensive tests, open plastic tubeswith internal lumen > 3 mm and up to 200 mm in lengthcan currently be sterilized. Tubes with internal lumen< 3 mm must be provided with a diffusion amplifier be-fore sterilization. Catheters which are closed at one endcannot be reliably sterilized.
The disadvantages of this process should be dis-cussed very specifically: hydrogen peroxide vapor isstrongly adsorbed by materials containing cellulose.Plasma sterilization therefore cannot be used for itemsto be sterilized which contain cellulose or for instru-ments in packaging containing cellulose. All packagingmaterials must be free from cellulose and are currentlyonly available from the operating company. Packagingbags, for example, are also on average three times moreexpensive than similar products for steam sterilization.Containers for instruments, such as those which areavailable for steam sterilization, are only in the devel-opment stages. The instruments must be completely drybefore loading the plasma sterilizer. In the case of or-ganic contamination of the surface, the effect of plasmasterilization is restricted considerably, but this is also thecase with all surface sterilization processes.
Inspection and Testing for Effectiveness. Test sys-tems with biological indicators in accordance withISO 14937 must be used to test effectiveness.
3.6 Hygiene of Noninvasive Technology Equipment
This category includes all equipment and technicalmeasures which are used for diagnosis and therapybut which are not inserted into the patient. Thesemay be electrocardiogram (ECG) electrodes, ultrasonictransducers or monitors by the patient’s bed or infunction-testing departments, and they may equally besmall conveyor systems, ventilation technology or pro-cessing machines.
3.6.1 Equipment Used on the Patient
These must be included in regular cleaning. If theequipment does not come into contact with the patient,
then cleaning – often only of the accessible surfaces– is usually sufficient. Environmentally friendly de-tergents should be given preference for this, and itis also important to bear in mind material compat-ibility and area-specific regulations (e.g., explosionprotection).
Where such equipment is in areas with increased re-quirements in terms of sterility (e.g., operating theaters)or in isolation rooms (infectious patients, patients withmultiresistant colonized bacteria, immunosuppressedpatients), disinfectant cleaning must be stipulated. Thedisinfectant used must be suitable for the field of use(disinfectants for treating surfaces or instruments) and
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must comply with requirements in the scope of its ef-fect. When used in areas with increased requirementsin terms of sterility, all potential pathogens should becovered, and when used in isolation areas, substancesare preferred which act very quickly against the knownpathogens with a long-lasting effect.
Equipment or equipment parts which come into con-tact with the patient must be cleaned carefully prior touse in accordance with the guidelines and must alwaysbe disinfected if there are corresponding regulations(e.g., after use on patients with multiresistant germs) orif, despite proper cleaning, there is still a risk of infec-tion, e.g., in the case of severely immunocompromisedpatients for whom even harmless environmental germscan become a threat.
3.6.2 Equipment Not Used on the Patient
Initially, the same requirements apply for this equip-ment as for use outside a hospital. It must be maintainedaccording to its intended purpose and regularly cleaned.Different requirements may be necessary when theequipment is used in areas with increased requirementsin terms of sterility, and, when necessary, these in-creased requirements should be governed by in-houseguidelines. If, as a result of use, the equipment/unitis contaminated with material from the patient, thendisinfectant cleaning is recommended, and if the ma-terial is from an infectious patient then disinfectantcleaning is a requirement. For certain equipment (e.g.,air-conditioning units, cleanroom benches), special reg-
ulations may need to be taken into account (seebelow).
3.6.3 Repair and Maintenance
Equipment which is handed in for repair and mainte-nance to relevant departments should have been given atleast basic cleaning beforehand. Equipment parts whichhave been in contact with patients/patient material mustonly be disinfected before being worked on if they arevisibly dirty, or if it can be assumed that it is con-taminated with germs which should be prevented fromspreading in the hospital (multiresistant germs), whichcan lead to infections in the maintenance staff, or whichare subject to special regulations by law (German Infec-tion Protection Act). These also include germs such ashepatitis and tuberculosis pathogens, and other similarpathogens.
Whether this pretreatment is carried out by the user,somebody in another position (processing unit) or themaintenance department itself may depend on the struc-ture of the organization and also on the size of thehospital. It is therefore recommended that the procedureand the respective responsibility are set down in writingand that hygiene plans are used to regulate who has todo what, when, and in particular precisely how, and inwhat sequence. This should in any case be agreed upontogether with the person responsible for hygiene (hy-giene officer/infection control nurse) and possibly alsowith the member of staff responsible for occupationalhealth and safety.
3.7 Hygiene of Invasive Technology Equipment
This includes all equipment, equipment parts, and tech-nical measures which are used for diagnosis or therapyand which in the process are inserted into the patient.These may either be instruments or equipment whichare used in the patient without penetrating the skin ormucosa (e.g., bronchoscope, oesophageal arteriography,suction aspirator), in which case there may be inten-tional (biopsy) or unintentional damage to the mucosa,or they may be instruments or equipment which are de-signed for use with or after penetration of the barrier of
the skin/mucosa (e.g., biopsy forceps, arthroscope, andvascular catheter).
Disinfectant measures are usually sufficient for thefirst group, whereas a sterilization process is obligatoryfor the second group (see above).
Here, too, the following general rule applies: Pri-marily use thermal disinfection (washing) processes,and only consider thermochemical or even purely chem-ical processes when the materials are not compatiblewith thermal disinfection processes.
3.8 Practical Examples
Targeted measures to prevent transmission of germs andinfections must be adapted to the pathogen, the group
of people, and the hazard potential. Vaccination alonemay be sufficient, or specific disinfection or steriliza-
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tion measures or even isolation of the patient may benecessary. The route of transmission plays a crucial rolein this (Table 3.5).
The German Infection Protection Act, which hasbeen in force since 1 January 2001 and has replaced the
Table 3.5 Types of infection transmission and their features and protective measures (after [3.15])
Type of transmission Features Examples Protective measures
Airborne transmission Microorganisms at-tached to particlesin the air with sizeof <5 μm, move-ment over a relativelylong period of timetherefore possible
1. Reasonable suspicion of orconfirmed tuberculosis2. Measles3. Varicella/disseminated her-pes zoster4. HIV patients with cough,fever, and opaque pulmonaryinfiltrates, provided TB cannotbe ruled out
1. Isolation in a singleroom (door and windowsclosed), cohort isolationpotentially possible2. Respiratory protectionwhen entering the room ifopen-lung TB is identifiedor there is strong clinicalsuspicion3. In the case of certaindiseases (measles, vari-cella) nonimmune peopleshould not enter the room;if unavoidable, only withrespiratory protection
Droplet transmission Microorganisms at-tached to particles>5 μm (these dropletsare created whenspeaking, coughing,and sneezing)
1. Bacterial diseases: H.influenzae (type B) infections,meningococcal infections,multiresistant pneumococcalinfections, diphtheria, pertus-sis, mycoplasma pneumoniainfections2. Viral diseases: influenza,mumps, rubella, parvovirusinfections
1. Single room, cohortisolation if necessary; ifnot possible a distance ofat least 1 m should be keptbetween the infectious pa-tient and other patients orvisitors2. Mouth and nose pro-tection required whenworking close to thepatient (<1 m distance)
Contact transmission Direct contact (touch-ing) or indirectcontact (secondary,e.g., via contami-nated surfaces) withepidemiologically im-portant pathogens inthe case of infected orcolonized patients
1. Infectious diarrheal diseases2. C. difficile enteritis3. Respiratory infections inchildren (bronchiolitis, croup)4. Multiresistant pathogenssuch as Methicillin-resistantStaphylococcus aureus(MRSA), Vancomycin-resistant Enterococcusfaecium (VRE) (except mul-tiresistant TB)5. Abscess or secretingwounds which cannot becovered
1. If possible single room;cohort isolation if neces-sary2. Gloves and gowns de-pending on the pathogenand site of the infection(follow infection controlrecommendations)3. Disinfect hands onleaving the room
old Federal Contagious Diseases Act, takes into con-sideration these findings but also takes into account theeffects of technology in the changing world of medicineby stipulating in § 23 that infections acquired in hospi-tals must be continuously recorded, even those which
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are particularly influenced by technical factors (devicerelated):
• Postoperative wound infections• Ventilator associated pneumonias• Catheter-related septicemias• Catheter-related urinary tract infections.
Because these are also the four most commonhealth-care acquired infections in hospitals and the mea-sures required by law make an important contributionto sensible quality management, the following practicalexamples are limited to these infections and demonstratethe vital contribution that technology can make here.
3.8.1 Postoperative Wound Infections
The pathogens for postoperative wound infections ei-ther originate from the patient himself (germs in the skinor mucous membranes) or are introduced into the pa-tient from outside during surgery as a result of a lack ofhygiene. Before many surgical procedures, hair removalup to now is still carried out using a razor (medicotech-nical measure). If this is done on the evening before theprocedure, then the bacteria from skin flora have timeovernight to migrate deep into the skin via the micro-scopic cuts in the skin which are unavoidably causedduring shaving to cause inflammation there. The re-sult is a significantly higher risk of developing surgicalsite infection. It is therefore recommended either not toshave at all and to simply cut the hair short using hairtrimmers, or to shave immediately before the surgeryand thus immediately before the skin is disinfected (seealso KRINKO recommendation for the prevention ofpostoperative infections in the operating field [3.9]).
Further important measures for the avoidance ofpostoperative wound infections which are proven intheir effectiveness and which relate to technical meansare: sterile instruments, sterile implants, reliably ster-ilized equipment parts which are required for surgery(suction apparatus, counter with connection cable, etc.),correctly functioning air-conditioning units, sufficientvacuum in the case of reprocessed reusable drainageequipment, etc. [3.16].
3.8.2 Ventilator-Associated Pneumonias(VAP)
Pneumonia is the second most common overall infec-tion in hospitals and is the most important in the caseof intensive care patients. It is seen as the primary orsecondary cause in 30–50% of deaths. With respect
to diagnosis related groups (DRGs), it is also signif-icant that health-care associated pneumonia increasesthe length of hospital stay by an average of 11.5 days.The main risk factor for developing health-care associ-ated pneumonia is mechanical ventilation.
According to the KRINKO evidence criteria, ori-entated towards the criteria of the Centers for DiseaseControl and Prevention (CDC) [3.17], the followingtechnically relevant points are important for targetedprevention [3.17–20].
1. Oral intubation is better than nasal (development ofmaxillary sinusitis); in the case of long-term artifi-cial respiration prefer tracheotomy.
2. Use sterile or disinfected tracheal tubes.3. Clean all equipment and tools thoroughly before
disinfection and sterilization.4. Do not carry out routine sterilization or disinfection
of the circulation system of ventilators and anes-thetic apparatus.
5. Do not change ventilator breathing circuits morefrequently than every 48 h, including tubes andexpiratory valves and also nebulizers and steam hu-midifiers, provided the equipment is only used forone patient (according to recent studies an intervalof 7 days between changing is even possible).
6. Do not use atmospheric humidifiers, which form aer-osols (= atomizer), if sterilization/disinfection andsterile water are not used on at least a daily basis.
7. Use sterile (not distilled or nonsterile) water forrinsing the processed equipment and tools which areused on the respiratory tract after they have beenchemically disinfected.
8. Do not reprocess equipment and tools which havebeen manufactured for single use, unless there is datato show that reprocessing does not pose any threat tothe patient and is cost-effective and that the function-ality of the equipment and tools is not altered.
9. Sterilize or disinfect ventilation breathing circuitsand humidifiers between use on different patients.
10. Do not use bacterial filters between the humidifierreservoir and the inspiratory tube.
11. Do not change the respiratory tube routinely if thesystem is connected to an heat and moisture ex-change (HME) or heat and moisture exchange filter(HMEF), provided it is only used on one patient.
12. Change tubes between patients, including noseclamps or masks, which are used to supply oxygenfrom a wall outlet.
13. Sterilize atmospheric humidifiers which are used ininhalation therapy, e.g., for tracheostomy patients,
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or disinfect between patients and every 24 h whenused on the same patient.
14. Sterilize or disinfect portable spirometers, oxygenprobes, and other respiratory tools which are usedon various patients between uses.
15. Anesthetic equipment: clean and then sterilize orthermally/chemically disinfect the reprocessableparts of the respiratory circuit (such as the endo-tracheal tube or mask, inspiratory and expiratorytube, Y-piece, bag valve mask, humidifier, and tube)between use on different patients and observe therelevant manufacturer’s instructions.
16. Pulmonary function testing: sterilize or disinfectreusable mouthpieces and tubes between differentpatients or in accordance with the manufacturer’sinstructions.
3.8.3 Catheter-Related Septicemia
Most cases of septicemia acquired in hospitals are theresult of using a vascular catheter. The most impor-tant points to avoid resulting infections are checkingof the indication for access, selection of the correctcatheter and the correct access site, aseptic placementof the catheter, and aseptic dressing change. The tech-nical component is comparatively low here and coversthe following points [3.21]:
1. Change IV tubes including the three-way valvesonly every 72 h (every 24 h when blood/blood prod-ucts or lipid solutions are administered), exceptwhere there are signs of infection.
2. When choosing transducers (pressure sensors), pref-erence should if possible be given to disposableitems (as opposed to reusable equipment).
3. The transducer, the tube system, and the rinse solu-tion must be changed at least every 96 h.
4. All components of the blood pressure monitoringsystem must be sterile (including the calibration ap-paratus and the rinsing fluid). The entire pressuresystem (tube lines, transducers, and rinse solution)must be handled aseptically.
5. Reusable pressure systems must be processed andsterilized taking into account the manufacturer’s in-structions.
6. If preparation of mixed infusions in areas close topatients is unavoidable, then it must be done undercontrolled aseptic conditions.
In past years it has been increasingly common to re-process certain expensive intravascular catheters within
the hospital or to have them reprocessed by externalproviders (see later). This practice is currently the sub-ject of controversial debate for very many differentreasons (German Medical Devices Act, costs, borinespongiform enphalopaty (BSE)). In this context, refer-ence should in particular be made to the recommenda-tions of the German Commission for Hospital Hygieneand Infection Prevention at the RKI [3.21] and [3.9]with the explanations from the RKI and the final re-port of the vCJD taskforce: variant Creutzfeldt–Jakobdisease (vCJD), epidemiology, identification, diagnosis,and prevention, with particular consideration of mini-mizing the risk of iatrogenic transmission via medicaldevices, particularly surgical instruments [3.22]. Refer-ence is further made to specific literature [3.23–26].
3.8.4 Catheter-Related Urinary TractInfection
Urinary tract infections make up more than 40% of allinfections acquired in hospital and, as the starting pointfor urosepsis, are responsible for up to 15% of cases ofsepticemia. Up to 80% of these urinary tract infectionsare found in patients with urinary catheters, which em-phasizes their significance. Technically relevant aspectsof targeted prevention are as follows:
• Urinary catheters should only be placed if medicallynecessary and only for as long as is absolutely nec-essary; an indication as part of nursing care must berejected.• Only sterile, permanently sealed urine drainage sys-tems with an antireflux valve should be used (i. e.,without disconnection to empty the bag) [3.27, 28].
3.8.5 Dialysis
Because of the high risk of infection both for patientsand also for staff, dialysis departments deserve specialattention. The risks of infection are:
1. For the patient:a) Infections via the vascular accessb) Bloodborne infectionsc) Contamination of the dialysate and dialyzer.
2. For the staff:a) Through infected dialysis systemsb) Infections via blood and dialysate.
In comparison with peritoneal dialysis, hemodial-ysis is more significant from a technical viewpoint
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and is the basis for the following explanations. How-ever, some of the requirements also apply to peritonealdialysis.
If drinking water is used for dialysis, it must un-dergo additional processing because it contains bacteriaand pyrogens, even if chlorinated. The processes usedfor this are ion exchange (water softening), activecarbon filtering, distillation, and reverse osmosis. How-ever, it must be borne in mind that particularly thefirst process mentioned can provide waterborne bacte-ria (mainly Pseudomonas spp. and other Gram-negativebacteria such as acinetobacter and enterobacter) but alsomycobacteria, which are present in water and are de-scribed as atypical, with good opportunities to multiply.Subsequent ultrafiltration to remove bacteria and bacte-rial toxins is therefore considered essential [3.29].
Although reverse osmosis is currently the most op-timum processing method, it is still necessary to takeinto account that, even with this method, there may bemicrobial contamination of the membrane, and germsmay find their way in if there are leaks. Once thedialysate is added, this forms a mixture which, be-cause of its composition, is a good culture mediumfor waterborne bacteria. Various countries have there-fore suggested guidelines for the assessment of dialysiswater (Table 3.6).
To prevent contamination of hemodialysis equip-ment and supply apparatus, the following technicalrequirements are deemed necessary [3.30]:
• No open reservoirs for water and processed dialysisfluid• No open reservoirs for concentrates• Small line cross-sections in supply lines• Route lines as a closed circular pipeline; avoid deadspaces (only for clean water)• Complete disinfectability of the line system• Pipe disconnection when disposing of the dialysisfluid to prevent retrograde microbial contamination.
In accordance with the hygiene guideline which isan appendix to the 2006 Dialysis Standard [3.31], dial-ysis equipment (hemo- and peritoneal dialysis) used
Table 3.6 Guidelines for assessment of dialysis water in various countries
Dialysis water (generally permeate) Dialysis fluid
(CFU/ml) Endotoxin (CFU/ml) Endotoxin
AAMI (USA 2004) ≤ 200 2 EU/ml ≤ 2000 2 EU/ml
European Pharmacopoeia (2008) ≤ 100 ≤ 0.25 IU/ml No information No information
Swedish Pharmacopoeia (1997) < 100 < 0.25 IU/ml < 100
Japanese Society for Dialysis Therapy (2008) < 100 < 0.05 EU/ml < 100 0.05 EU/ml
must comply with the regulations of the German Med-ical Devices Act and must be maintained, operated,cleaned, and disinfected in accordance with the man-ufacturer’s instructions (instructions for use, technicalmanual) [3.30]. Due to this required disinfection aftereach patient, the formerly required separation into a so-called yellow (for infectious patients) and white (fornoninfectious patients) region is now obsolete. The op-erator is responsible for ensuring that all parts whichcome into contact with the used dialysate or even withthe patient’s blood are treated as potentially infectiousand that the equipment is disinfected after each dialysistreatment.
This can be done by [3.29]:
• Sterilization with steam at a temperature of 121 ◦C,provided this is technically possible from a mater-ials point of view (equipment with stainless-steeltanks)• Disinfection using hot water (90–95 ◦C for 20 min);citric acid is automatically added during the processto prevent deposits in the equipment• Thermochemical disinfection (for ecological rea-sons, preferably with peracetic acid, possiblyalso with formaldehyde or glutaraldehyde or withsodium hypochlorite).
Dialyzers have been regularly reprocessed in thepast. Figures for the USA show that the proportion ofdialysis centers reprocessing their equipment rose from18% in 1976 to 82% in 1997 [3.32], and correspond-ing processing guidelines issued by the Association forthe Advancement of Medical Instrumentation (AAMI)were adopted by official authorities [3.33]. The per-centage then dropped to 62% by 2002. The literaturedescribes infectious complications through to outbreaksin the course of reprocessing dialyzers, without be-ing able to prove causality beyond doubt [3.34]. Forquality assurance purposes it is therefore necessaryto ensure that effective processes are used, which arecurrently based on thermochemical disinfection. Thehygiene guideline which is an appendix to the 2006Dialysis Standard – written by the German Commit-
PartA
3.8
Hygiene in Medical Technology 3.9 Regulations 31
tee for Clinical Nephrology in collaboration with theAssociation of German Nephrology Centers run bythe German Society of Nephrologists in Private Prac-tice and also with the German Society of PediatricNephrology, in agreement with the German Commis-sion for Hospital Hygiene and Infection Prevention– likewise points to the requirements for a process-ing method with appropriate validation and stressesthat the German Committee for Nephrology currentlydoes not favor reuse of dialyzers and tube systems,despite the financial ramifications [3.30]. Tests to mon-itor clean water and dialysis fluid must be performedand documented at least twice a year [3.30, 35]. Therelevant water-conducting systems (e.g., closed circu-lar pipelines) must be fitted with suitable samplingpoints.
The following procedure is considered necessary totest the microbiological quality of the water [3.35]:
• Disinfect hands before each sample is taken• Use sterile glass bottles with a screw closure forcollecting the sample; to test for endotoxins usepyrogen-free containers made from polystyrene• Draw off ≈ 100 ml in each case• Demineralized water– From the closed circular pipeline at the bedside– Aseptic sampling (disinfected adapter, at least
twice a year)• Basic bicarbonate– Only if it is taken as a concentrate from a closed
circular pipeline at the bedside (not from canis-ters or cartridges)
– Aseptic sampling (disinfected adapter)– Once a month• Dialysis fluid– Sample taken from the dialyzer– Before the start and after the end of dialysis– Every 6 months
• The assessment is performed according to the fol-lowing guidelines– In the processed water and in the dialysis fluid
before the beginning of dialysis: 100 CFU/ml.
In an ISO standard [3.36] which appeared in 2009and in which the quality of fluids for hemodialysis isformulated as an international standard, requirements,and limit values for the chemical constituents and impu-rities in water, concentrate, and dialysis fluid are listedin addition to microbiological quality standards. Theoperator of specialist dialysis departments is responsi-ble for monitoring of microbiological water quality andalso for chemical monitoring.
3.8.6 Creutzfeldt–Jakob Disease
After medical devices have been used on patients witha proven or strongly suspected case of Creutzfeldt–Jakob disease (CJD) or its new variant (vCJD), spe-cial processing procedures are necessary [3.22, 25].According to the currently favored prion theory, par-ticular significance is attributed to the cleaning whichtakes place during processing, because proteins mustprimarily be removed. For disinfectant processing,1–2 M sodium hydroxide (NaOH), 2.5–5% sodiumhypochlorite (NaOCl), or 4 M guanidinium thiocyanate(GdnSCN) is currently recommended [3.22].
Instruments which cannot be steam-sterilized arethen subsequently processed with aldehyde disinfectantand finally rinsed with 70% alcohol (e.g., endoscope)and gas-sterilized.
Instruments which can be steam-sterilized undergochemical decontamination before then being subjectedto machine processing at 93 ◦C, and are finally auto-claved at 134 ◦C for 1 h.
The relevant appendices to the RKI guideline mustbe observed [3.22].
3.9 Regulations
3.9.1 Technical Regulationsfor Hazardous Substances
• TRGS 513. Fumigations with ethylene oxide andformaldehyde in sterilization and disinfection sys-tems (edition June 2008).• TRGS 525. Handling of hazardous substances in fa-cilities for human medical care (as of May 1998
BArbBl. no. 5/1998, p. 58, currently undergoing re-vision).• TRGS 401. Hazards due to skin contact (as of June2008).• TRBA/TRGS 406. Sensitizing substances for theairways (as of June 2008).• TRBA 250. Technical regulations for biologicalagents (as of February 2008).
PartA
3.9
32 Part A Medical Technology Basics
3.9.2 Standards
The importance of standards has been re-evaluated asa result of Directive 93/42/EEC about medical devicesand the correspondingly harmonized German Medical
Table 3.7 Standards for the (minimum) standard for medi-cal devices �
Table 3.8 Overview of major standards in the field of sterilization technology for the health care system
Standard Steam sterilization As of
DIN EN 285 Sterilization – steam sterilizers – large sterilizers 8/2009
DIN EN/ISO 17665-1 Requirements for the development, validation, and routine control of a sterilization processfor medical devices
11/2006
DIN 58948 Sterilization – low-temperature steam formaldehyde sterilizers
Section 17 Requirements for the installation and operation of low-temperature steam formaldehyde andformaldehyde sterilizers and their supply sources
3/2009
DIN EN 14180 Sterilizers for medical purposesLow-temperature steam and formaldehyde sterilizers – requirements and testing
1/2010
Standard Ethylene oxide sterilization As of
DIN EN 1422 Sterilizers for medical purposes – ethylene oxide sterilizers – requirements and test methods 8/2009
DIN 58948-7 Requirements on the installation and requirements on the service supply for ethylene oxidesterilizers
1/2010
DIN 58949 Steam disinfection apparatus As of
Section 1 Terminology 1/2001
Section 2 Requirements 1/2001
Section 3 Efficiency testing 2/2004
Section 4 Biological indicators for efficacy tests 10/2006
Section 6 Operating of steam disinfection apparatus 2/2004
Section 7 Structural requirements and requirements on service supply 1/2001
DIN 58955 Decontamination equipment for medical use As of
Section 1 Terminology 1/2003
Section 2 Requirements 7/2005
Section 3 Efficiency testing 9/1998
Section 4 Biological indicators for efficacy tests 3/2006
Section 6 Operation 3/2001
Section 7 Structural requirements and requirements on service supply 3/2001
DIN EN/ISO 11138 Sterilization of health care products – biological indicators
Section 1 Requirements 8/2008
Section 2 Biological indicators for ethylene oxide sterilization processes 9/2009
Section 3 Biological indicators for moist heat sterilization processes 9/2009
Section 4 Biological indicators for dry heat sterilization processes 9/2006
Section 5 Biological indicators for low-temperature steam and formaldehyde sterilization processes 9/2007
DIN 58921 Draft standard: Test method to demonstrate the suitability of a medical device simulatorduring steam sterilization – medical device simulator testing
12/2008
DIN EN/ISO 11140 Sterilization of health care products – chemical indicators
Section 1 General requirements 9/2009
Section 3 Class 2 indicator systems for use in the Bowie and Dick-type steam penetration test 9/2009
Section 4 Class 2 indicators as an alternative to the Bowie and Dick-type test for detection of steampenetration
7/2007
Type of standard Source
DIN German standard
E DIN Published German draft standard
EN European standard
DIN EN Harmonized (European) standard
prEN, E Published European draft standard
DIN EN/ISO International standard
PartA
3.9
Hygiene in Medical Technology References 33
Devices Act. They specify the (minimum) state of theart which the manufacturer must observe during thedesign, manufacture, operation, and use of medical de-
vices (Table 3.7). Table 3.8 gives an overview of majorstandards in the field of sterilization technology for thehealth care system.
References
3.1 W.E. Stamm: Infections due to medical devices, Part
2, Annu. Intern. Med. 89, 764–769 (1978)
3.2 F. Hofmann: Arbeitsmedizin und Gesundheitsschutz
im Krankenhaus. In: Praktische Krankenhaushy-
giene und Umweltschutz, ed. by F. Daschner
(Springer, Berlin, Heidelberg 1997)
3.3 A.R. Aitkenhead, J.F. Dhainaut: International stan-
dards for safety in the intensive care unit, Intensive
Care Med. 19, 178–181 (1993)
3.4 P. Gastmeier, K. Weist, O. Weigt, H. Rüden: Präven-
tion nosokomialer Infektionen in der Intensivstation
und im OP, Anästhesist 48, 575–590 (1999)
3.5 M.A. Martin: Nosocomial infections related to pa-
tient care support services: Dietetic services, central
services department, laundry, respiratory care, dial-
ysis, and enoscopy. In: Prevention and Control of
Nosocomial Infections, ed. by R.P. Wenzel (Williams,
Philadelphia 1997)
3.6 Robert-Koch-Institut: Impfempfehlungen der Stän-
digen Impfkommission (STIKO) am Robert-Koch-In-
stitut/Stand Juli 2009 (2000) http://www.rki.de/ (last
accessed July 2011)
3.7 Robert-Koch-Institut: Liste der vom Robert-Koch-
Institut geprüften und anerkannten Desinfektions-
mittel und -verfahren, Stand vom 31.05.2003, 14.
Ausgabe, Bundesgesundheitsblatt 46, 72–95 (2003)
3.8 KRINKO: Anforderungen an die Hygiene bei der
Reinigung und Desinfektion von Flächen, Mit-
teilung der Kommission für Krankenhaushygiene
und Infektionsprävention am Robert Koch-Institut,
Bundesgesundheitsblatt 47, 51–61 (2004)
3.9 KRINKO: Anforderungen an die Hygiene bei der Auf-
bereitung von Medizinprodukten, Mitteilung der
Kommission für Krankenhaushygiene und Infek-
tionsprävention am Robert Koch-Institut, Bundes-
gesundheitsblatt 44, 1115–1126 (2001)
3.10 C. Ruef, S. Harbarth, A. Henry, D. Pittet: Sterilisa-
tion mit Ethylenoxid: Anwendungen und Grenzen,
Swiss-NOSO 4, 3–6 (1997)
3.11 V. Herzog: Desorption von Ethylenoxid (EO) zur
Einhaltung der Grenzwerte, Zentralsterilisation 8,
204–209 (2000)
3.12 P. Mecke: Wasserstoffperoxid-Plasma, Ein interes-
santes mikrobizides Prinzip, Hyg. Med. 17, 537–542
(1992)
3.13 A.F. Widmer, H. Siegrist: Plasmasterilisation: Eine
revolutionäre Technik für thermolabile Instrumente,
Swiss-NOSO 1, 7 (1994)
3.14 M. Borneff, U. Färber, H. Getreuer, P. Heeg, C. Höller,
U. Junghannß, H. Martiny, R. Mechmerth, P. Mecke,
J. Peters, : Zur Wirksamkeit und Prüfung von
H2O2-Plasma-Sterilisatoren, Hyg. Med. 18, 557–558
(1993)
3.15 H.M. Just, R. Ziegler: Isolierungsmaßnahmen. In:
Praktische Krankenhaushygiene und Umweltschutz,
ed. by F. Daschner (Springer, Berlin, Heidelberg
2006)
3.16 KRINKO: Prävention postoperativer Infektionen im
Operationsgebiet, Mitteilung der Kommission für
Krankenhaushygiene und Infektionsprävention am
Robert Koch-Institut, Bundesgesundheitsblatt 50,
377–393 (2007)
3.17 KRINKO: Prävention der Nosokomialen Pneumonie,
Mitteilung der Kommission für Krankenhaushygiene
und Infektionsprävention am Robert Koch-Institut,
Bundesgesundheitsblatt 43, 302–309 (2000)
3.18 D. Craven, K.A. Steger: Nosocomial pneumonia in
mechanically ventilated adult patients: Epidemiol-
ogy and prevention in 1996, Semin. Respir. Infect.
11, 32–53 (1996)
3.19 M.H. Kolleff: The prevention of ventilator-associated
pneumonia, Curr. Concepts 340, 627–634 (1999)
3.20 M. Lacour, P. Gastmeier, H. Rüden, F. Daschner:
Prävention der nosokomialen Pneumonie, Emp-
fehlungen des Nationalen Referenzzentrums (NRZ)
für Krankenhaushygiene, 1. Prävention der Beat-
mungspneumonie, Intensivmedizin 35, 87–94
(1998)
3.21 KRINKO: Prävention Gefäßkatheter-assoziierter In-
fektionen, Mitteilung der Kommission für Kranken-
haushygiene und Infektionsprävention am Robert
Koch-Institut, Bundesgesundheitsblatt 45, 907–924
(2002)
3.22 Verhütung und Kontrolle von TSE: Die Variante
der Creutzfeldt-Jakob-Krankheit (vCJK). Epidemi-
ologie, Erkennung, Diagnostik und Prävention unter
besonderer Berücksichtigung der Risikominimierung
einer iatrogenen Übertragung durch Medizinpro-
dukte, insbesondere chirurgische Instrumente –
Abschlussbericht der Task Force vCJK zu diesem
Thema, Mitteilung der Robert Koch Instituts, Bun-
desgesundheitsblatt 45, 376–394 (2002)
3.23 H. Baron, J. Safar, D. Groth, S.J.. DeArmond: Prions.
In: Disinfection, Sterilization, and Preservation, ed.
by S.S. Block (Lippincott, Philadelphia 2001)
3.24 P. Gastmeier: Device-associated nosocomial infec-
tion surveillance in neonatal intensive care using
specified criteria for neonates, J. Hosp. Infect. 38,
51–60 (1998)
3.25 B. Hörnlimann, D. Riesner, H. Kretzschmar (Eds.):
Prionen und Prionkrankheiten (De Gruyter, Berlin
2001)
PartA
3
34 Part A Medical Technology Basics
3.26 M. Lacour: Prävention von Infektionen durch in-
travasale Katheter, Intensivmedizin 35, 582–592
(1998)
3.27 D.H. Forster, P. Gastmeier, H. Rüden, F. Daschner:
Prävention nosokomialer Harnweginfektionen, In-
tensivmedizin 36, 15–26 (1999)
3.28 J. Martius, P. Brühl, M. Dettenkofer, U. Hartenau-
er, S. Niklas, H.-J. Piechota: KRINKO Prävention
und Kontrolle Katheter-assoziierter Harnwegsinfek-
tionen. Mitteilung der Kommission für Kranken-
haushygiene und Infektionsprävention am Robert
Koch-Institut, Bundesgesundheitsblatt 42, 806–809
(1999)
3.29 H. Gartmann, M. Dettenkofer: Dialyse. In: Prakti-
sche Krankenhaushygiene und Umweltschutz, ed.
by F. Daschner (Springer, Berlin, Heidelberg 2006)
3.30 Dialyseeinheiten (2008) Hygieneleitlinie als Ergän-
zung zum Dialysestandard 2006 der Deutschen
Arbeitsgemeinschaft für Klinische Nephrologie e.V.
in Zusammenarbeit mit dem Verband deutsche
Nierenzentren der DD nÄ e.V. sowie der Gesellschaft
für pädiatrische Nephrologie (GPN) in Abstimmung
mit der KRINKO www.nephrologle.de/Leitlinie.pdf
bzw. www.rki.de (last accessed July 2011)
3.31 Dialysestandard 2006 der Deutschen Arbeitsgemein-
schaft für klinische Nephrologie, Mitt. Arb. Klin. Ne-
phro. 35, 121–184 (2006), http://www.nephrologie.
de/Richtlinien.html (last accessed July 2011)
3.32 J.I. Tokars, E.R. Miller, M.J. Alter, M.J. Arduino:
National surveillance of dialysis-associated dis-
eases in the United States, Semin. Dial. 13, 75–85
(2000)
3.33 AAMI: American National Standard: Reuse of
Hemodialyzers ANSI/AAMI RD47-2002/A1:2003 (Asso-
ciation Advancement of Medical Instrumentation,
Arlington 2003)
3.34 J.M. Arduino: Dialysis-associated complications and
their control. In: Bennett and Brachmann’s Hospital
Infections, ed. by W.R. Jarvis (Lippincott, Philadel-
phia 2007)
3.35 A. Podbielski, M. Herrmann, E. Kniehl, H. Mauch:
MiQ: Qualitätsstandards in der mikrobiologisch-
infektiologischen Diagnostik, Teil 1 (Elsevier, Munich
2005) pp. 22–27
3.36 ISO 11663: Quality of Dialysis Fluid for Hemodial-
ysis and Related Therapies (International Or-
ganization for Standardization, Geneva 2009),
http://www.iso.org/ (last accessed July 2011)
PartA
3
35
Technical Saf4. Technical Safety of Electrical Medical TechnologyEquipment and Systems
Rüdiger Kramme, Hans-Peter Uhlig
Medical electrical (ME) equipment and systems
are used primarily in medical institutions such
as doctors’ surgeries, dental surgeries, medical
centers, outpatient clinics, rehabilitation clinics,
sanatoriums, health clinics, nursing homes for
the elderly, homes for the disabled and those
with learning difficulties, and hospitals and clin-
ics. According to the regulations and standards
for electrical systems, suitable rooms – areas
used for medical purposes – must be present
in these institutions in which mains-operated
ME equipment can be operated. Many questions
emerge concerning the use of this equipment,
on the one hand relating to the safety of pa-
tients and those operating the equipment, and
on the other hand relating to the smooth op-
eration of this apparatus. The main risks posed
by these pieces of ME equipment and ME sys-
tems may be of electrical, mechanical or thermal
nature. Other possible potential risks are ioniz-
ing radiation, explosion or fire as outlined in this
chapter.
4.1 General Information Regardingthe Safety of Technical Systems.............. 36
4.2 Attaining Safety in Medical Institutions .. 36
4.3 Minimum Requirementsfor ME Equipment ................................. 37
4.4 Areas Used for Medical Purposes ............ 40
4.5 Electrical Systems Accordingto the Nature of the Connection to Earth 42
4.6 Protection Against Shock Currents .......... 42
4.7 Power Supply ....................................... 44
4.8 Power Sources for Safety Purposeswith Accumulators ................................ 44
4.9 Final Circuits and Plug Sockets ............... 45
4.10 Static Electricity .................................... 45
4.11 Electromagnetic Compatibility ............... 46
4.12 Conclusions .......................................... 47
References .................................................. 47
What is meant by risks and hazard? Risks in an opera-tional process are components of the working systemwhich can damage the life or health of operatingstaff or patients. These risks are energy sources orare connected to them. When this energy is greaterthan the electrical resistance of the human body or anaffected body part, the energy is of a damaging na-ture. The damaging force is derived from the ratio ofenergy to body resistance. A hazard is described asthe possibility of humans encountering risks in spaceand time. To provide safe medical workplaces, it istherefore necessary to clarify how and under what
operating conditions humans encounter risks and therisk of injury occurs, and what successful safety mea-sures (protection objectives) are or should be in useto guard against this [4.1]. The largest proportion ofpossible hazards result from ME equipment and MEsystems for diagnosis, therapy, and monitoring. Thecommonest causes of an electrical accident can be at-tributed to malfunctioning protective devices, defectiveinsulation on cables and wires, defective or missingprotective covers on equipment and plug connectors,and missing, disconnected or interchanged protectiveearths.
PartA
4
36 Part A Medical Technology Basics
4.1 General Information Regarding the Safety of Technical Systems
The current state of science and technology which hasbeen achieved in principle makes it possible to developand build technical products and systems which are verysafe. Absolute safety nevertheless does not exist, eitherin life or in technology. The important thing is thereforeto ascertain the justifiable residual risk in each individ-ual case, then to consciously live with this risk [4.2].
DIN 31000 general guidelines for the safety de-sign of technical products (Allgemeine Leitsätze fürdas sicherheitsgerechte Gestalten technischer Erzeug-nisse), dated 03/1979, forms the basis for the contentof safety standards and VDE (Verband der Elektrotech-nik, Elektronik und Informationstechnik, Associationfor Electrical, Electronic and Information Technology)specifications. In DIN 31000 part 2, dated 12/1987,which was unfortunately withdrawn in 2005, borderlinerisk is described as the greatest risk relating to a certaintechnical process or condition that is still consideredjustifiable. Safety is defined according to DIN VDE31000 part 2 as a circumstance in which the residualrisk remains below a defined borderline risk. The levelof risk is formed as an abstract variable from the prod-uct of the extent of damage and probability of damageoccurring [4.3]. The temporal and content-based limiton safety resulting from this is achieved through thedescription of appropriate requirements or measures.
The measures which ensure safety are divided intothree classes according to DIN 31000 part 1 (three-classtheory).
1. Direct safety engineering includes measures whichprovide safety mainly through constructive, planning-related engineering of products and systems and theirparts.
2. Indirect safety engineering is understood as mean-ing the application of safety-related means, e.g.,locking mechanisms.
3. Indicative safety engineering is produced by guide-lines regarding the conditions for risk-free use –e.g., in operating instructions and on signs – whendirect and indirect safety engineering do not, or donot completely, achieve their goal.
In the case of all of the safety-engineering measuresmentioned, use of the products and systems accord-ing to their intended purpose is a precondition. Thefirst-fault philosophy, described in DIN VDE 0752supplementary sheet 1, dated 03/2003, forms an im-portant foundation when assessing hazard situations.The findings of the international standardization onthe subject of safety, such as the contents of IEC300-3-9, dated 12/1995 (Dependability Management;Part 3: Application Guide; Section 9: Risk Analysisof Technological Systems), can also be used [4.2].The possible consequences of first faults are virtuallyruled out by protective measures and by scheduledtesting and maintenance. Suitable monitoring devicesmust immediately discover any first faults which mightoccur.
4.2 Attaining Safety in Medical Institutions
In Germany there are very comprehensive regulations,provisions, standards, and guidelines which apply tothe planning, installation, refurbishment, and testing ofelectrical systems in medical institutions. The same ap-plies to the development, manufacture, and operationof ME equipment and ME systems. The crossoversor points of intersection between these documentsare unfortunately not defined but are instead fluid.So, for example, different provisions and standardsfor ME equipment contain important requirementsregarding the planning and installation of electricalsystems.
Provisions and standards in principle contain only theminimum requirements, and there is not always confor-mity between them. In addition, they do not always reflectthe state of the art, because in many cases technologi-cal developments move at a faster rate than revision ofthese documents is carried out. Each individual projectmust therefore be checked both with regard to observanceof the statutory and normative minimum requirementsand with regard to additional requirements. The requiredsafety can in principle only be achieved if the overall sys-tem, consisting of the physical structure and technicalsystems as well as the ME equipment, is safe.
PartA
4.2
Technical Safety of Electrical Medical Technology Equipment and Systems 4.3 Minimum Requirements for ME Equipment 37
The safety of the system consisting of electricalsystem/ME equipment is essentially described by theprotection objectives [4.2].
• Protection of patients and staff from shock currentsand from the risks of power failure or of poor-quality voltage or frequency• Safety of the interface between the ME equipmentand the electrical system, in particular when usingequipment for vital purposes
• Safety of the escape and emergency routes• Protection from fires and their effect on the systemof electrical installations and ME equipment overa required period of time• Safety as a result of using reliable technology• Safety as a result of using all of the sys-tem components according to their intended pur-pose• Safety as a result of operation in accordance withregulations and regular maintenance.
4.3 Minimum Requirements for ME Equipment
DIN EN 60601-1 (classified as VDE 0750-1) Med-ical electrical equipment: General requirements forbasic safety and essential performance (Medizini-sche elektrische Geräte; Allgemeine Festlegungen fürdie Sicherheit einschließlich der wesentlichen Leis-tungsmerkmale), dated 2007 (which replaces the 1996edition), is the basic standard in this series and describesthe general requirements for ME equipment. All ap-proved ME equipment in Germany must be built andtested according to the standards of the DIN EN 60601series. The basic standard DIN EN 60601-1 is evalu-ated here based mainly in connection to the electricalsystem. The protection classes I and II are approved formains-operated ME equipment.
In protection class I, all nonactive parts of the MEequipment are connected to the protective earth (PE).The equipment housing is composed of metal and islikewise connected to the PE. In the event of a fault toframe or earth fault internally in the equipment (e.g., in-sulation fault) between an active conductor and the PE,a protective device is triggered in the equipment and/orin the electrical system and the electrical circuit affectedis disconnected. During a fault situation, a contact volt-age occurs between the housing of the equipment andother earthed components.
The definition of ME equipment in protection class Iwhich is given in DIN 60601-1.
The equipment in protection class II is double in-sulated (all-insulated). A fault can only occur betweenactive conductors or an active conductor and the neu-tral conductor (N). No contact voltage to earth occursduring a first fault to frame or earth fault.
The definition of ME equipment in protectionclass II which is given in DIN EN 60601-1.
Another category is made up mostly by battery-operated ME equipment which does not rely on mainselectricity. As in mains-operated ME equipment of pro-tection class II, with regard to protection against shockcurrents, this equipment is not dependent on the in-stalled protective measures.
Equipment in class AP (anaesthetic proof (low risk))must comply with the requirements regarding con-struction, labeling, and accompanying documentation toavoid ignition sources in explosive mixtures of inhala-tional anesthetic agents with air.
Equipment in class APG (anaesthetic proof, Cat. G(high risk)) must comply with the requirements regard-ing construction, labeling, and accompanying documen-tation to avoid ignition sources in explosive mixturesof inhalational anesthetic agents with oxygen or nitrousoxide.
A distinction is also made between ME equipmentaccording to the insulation classes of the applied parts.
• Insulation class B: The applied part is connectedto earth. External application to the patient. Pro-vides protection against electric shock by taking intoaccount the fault current. Not suitable for direct ap-plication to the heart.• Insulation class BF: The applied part is insulatedfrom the ME equipment (no connection to earth).External application to the patient, higher-qualityprotection against electric shock than in insulationclass B. Not suitable for direct application to theheart.• Insulation class CF: The applied part is insulated toa high level from the ME equipment (no connec-tion to earth). External and intracardiac application
PartA
4.3
38 Part A Medical Technology Basics
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2M
Eeq
uipm
ent
prot
ectio
ncl
ass
1or
2
Inve
stig
atio
nsan
d/or
ther
apie
sdi
rect
lyon
the
hear
tan
dno
tre
peat
able
2Pr
ohib
ited
Pres
crib
ed(V
DE
0100
-71
0)
Not
perm
issi
ble
inpa
tient
envi
ronm
ent
Man
dato
ryPo
ssib
lein
prot
ectio
ncl
ass
II
Onl
yw
hen
ME
equi
pmen
tis
suita
ble
Onl
yw
hen
ME
equi
pmen
tis
suita
ble
If requ
ired
for
safe
oper
atio
nof
the
ME
equi
pmen
t
Proh
ibite
d(V
DE
0100
-710
)
3M
Eeq
uipm
ent
prot
ectio
ncl
ass
1an
d2
Inve
stig
atio
nsan
d/or
ther
apie
sno
tdir
ectly
onth
ehe
art
and
not
repe
atab
le
2Pr
ohib
ited
Pres
crib
ed(V
DE
0100
-71
0)
Pres
crib
ed(V
DE
0100
-710
)
Not
appl
icab
leA
llow
edin
case
ofpr
otec
tion
thro
ugh
insu
latio
nan
dco
atin
gor
cove
rage
Onl
yw
hen
ME
equi
pmen
tis
suita
ble
Onl
yw
hen
ME
equi
pmen
tis
suita
ble
If requ
ired
for
safe
oper
atio
nof
the
ME
equi
pmen
t
Proh
ibite
d(V
DE
0100
-710
)
4M
Eeq
uipm
ent
prot
ectio
ncl
ass
1an
d2
Inve
stig
atio
nsan
d/or
ther
apie
sno
tdir
ectly
onth
ehe
art
and
repe
atab
le
1A
llow
ed(V
DE
0100
-710
)
Allo
wed
,bu
tnot
pres
crib
ed
Pres
crib
ed(V
DE
0100
-710
)
Not
appl
icab
leA
llow
edin
case
ofpr
otec
tion
thro
ugh
insu
latio
nan
dco
atin
gor
cove
rage
Allo
wed
,bu
tnot
pres
crib
ed
Allo
wed
,bu
tnot
pres
crib
ed
Allo
wed
,bu
tnot
pres
crib
ed
Allo
wed
5O
pera
tion
thea
tre
(OT
)lig
hts
Illu
min
atio
nof
wor
kar
ea2
Proh
ibite
dPr
escr
ibed
atV
n>
25V
AC
(VD
E01
00-
710)
Pres
crib
ed(V
DE
0100
-710
)
For
ther
apie
s:to
bete
sted
dire
ctly
onth
ehe
art
Pres
crib
edat
Vn
≤25
VA
C(V
DE
0100
-710
)
Proh
ibite
d(V
DE
0100
-710
)
Pres
crib
ed(V
DE
0100
-710
)
Bes
tso
lutio
nPr
ohib
ited
(VD
E01
00-7
10)
PartA
4.3
Technical Safety of Electrical Medical Technology Equipment and Systems 4.3 Minimum Requirements for ME Equipment 39
Con
sum
-ab
les
App
lied
for
Pro
tect
ion
agai
nst
elec
tric
shoc
kP
ower
supp
ly
Dis
con-
nect
ion
ITsy
stem
ΔU ≤25
VΔ
U ≤10
mV
Pro
tect
ive
extr
alo
wvo
ltag
e(P
ELV
)25
V
For
safe
typu
rpos
esw
ith
perm
issi
ble
inte
rrup
tion
tim
eV
iage
nera
lpo
wer
supp
ly
Ser. no.
Medical area of group
≤15
s≤
0.5
s0.
0s
6O
Tm
icro
scop
esIl
lum
inat
ion
ofw
ork
area
2Pr
ohib
ited
Pres
crib
edat
Vn
>25
VA
C(V
DE
0100
-71
0)
Pres
crib
ed(V
DE
0100
-710
)
For
ther
apie
s:to
bete
sted
dire
ctly
onth
ehe
art
Pres
crib
edat
Vn
≤25
VA
C(V
DE
0100
-710
)
Proh
ibite
d(V
DE
0100
-710
)
Pres
crib
ed(V
DE
0100
-710
)
Bes
tso
lutio
nPr
ohib
ited
(VD
E01
00-7
10)
7E
xam
inat
ion
light
sIl
lum
inat
ion
ofw
ork
area
for
sim
ple
exam
inat
ions
1A
llow
ed(V
DE
0100
-710
)
Allo
wed
,bu
tnot
pres
crib
ed
Pres
crib
ed(V
DE
0100
-710
)
Not
appl
icab
leN
otap
plic
able
Acc
ordi
ngto
VD
E01
00-7
10no
tre
quir
ed,
tobe
test
edin
indi
vidu
alca
ses
Allo
wed
,bu
tnot
pres
crib
ed
Allo
wed
,bu
tnot
pres
crib
ed
Allo
wed
,bu
tnot
sens
ible
inal
lcas
es
8E
xam
inat
ion
light
sIl
lum
inat
ion
ofw
ork
area
for
sim
ple
exam
inat
ions
0A
llow
ed(V
DE
0100
-710
)
Not
appl
icab
leN
otap
plic
able
Not
appl
icab
leN
otap
plic
able
Acc
ordi
ngto
VD
E01
00-7
10no
tre
quir
ed,
tobe
test
edin
indi
vidu
alca
ses
Not
appl
icab
leN
otap
plic
able
Allo
wed
,bu
tnot
sens
ible
inal
lcas
es
Table 4.1 Requirements ofthe electrical system for MEequipment
PartA
4.3
40 Part A Medical Technology Basics
to the patient, higher-quality protection against elec-tric shock than in insulation class BF. Suitable fordirect application to the heart.
DIN EN 60601-1 applies accordingly to the safety ofME equipment.
Prerequisites for this are performance of risk man-agement processes, use of the equipment accordingto its intended purpose, and compliance with the in-structions from the manufacturer. The following areconsidered to be first faults for ME equipment.
1. Break in the protective earth.2. Break in a power supply cable.3. Occurrence of an external voltage at applied parts
with code letter “F”.4. Occurrence of an external voltage at signal input or
output parts.5. Failure of an electrical component.
The rated voltage may be a maximum of 250 V forhandheld ME equipment. For ME equipment and MEsystems which are operated on direct current or single-phase alternating current, the maximum value is 250 Vat a power limitation of 4 kV A. For ME equipment andME systems operated on polyphase current, the upperlimit of the rated voltage is 500 V.
The tolerance of the nominal voltage for ME equip-ment is ±10% and that of the mains frequency is≤ 1 Hz. According to the standards which apply to elec-trical systems, other values may also occur in this case(Sect. 4.7).
The protective earth of the equipment must bechecked regularly. A limit value of 0.1 Ω is permitted
between the PE of the plug and exposed metal parts(housing) for equipment with a permanently connectedpower supply cord, and of 0.2 Ω for equipment witha removable power supply cord.
The collateral standard DIN EN 60601-1-1 stipu-lates that, when using portable multiple sockets, it mustbe possible to connect the ME equipment of an ME sys-tem to a multiple socket only with the aid of a tool.Multiple sockets of this kind are available factory-builtin accordance with DIN EN 60601-1-1. Alternatively,the portable multiple socket must be electrically isolated(e.g., isolating transformer).
It is worth noting that electrically wired toroidaltransformers are frequently used as isolating transform-ers. There is no proof of safety from first faults for thisarrangement. The same applies to the supply of entireME systems from one power socket. Complete powerfailure is possible at any time.
The conclusion is that the safest kind of powersupply is the supply of ME systems from fixedsingle power sockets, especially for vital purposes,being connected to an information technology (IT)system.
Some of the requirements for ME equipment in DINEN 60601-1 which have been mentioned have a director indirect bearing on the electrical system. Some ad-ditional requirements for the electrical system can befound there [4.2].
Table 4.1 summarizes the various applications ofME equipment such that the most important require-ments can be recognized at the interface with theelectrical system and additional requirements can bedefined.
4.4 Areas Used for Medical Purposes
Medical examinations and treatments must be carriedout in appropriate rooms, areas used for medical pur-poses, regardless of where these rooms are. It may bea hospital, medical center or health center, an outpa-tient clinic or a private doctor’s practice. The use ofmedical procedures requires the areas used for medicalpurposes to be divided into the groups 0, 1 or 2 (DINVDE 0100-710).
There are specific hazards caused by the possi-ble condition of patients, such as unconsciousness, orthe nature of the medical examination or treatment,e.g., an operation. A patient’s skin resistance can becompromised as a result of medical interventions, anda patient’s cognitive ability or the body’s defenses can
be impaired or limited as a result of medical treat-ment. It is mandatory that the required classificationand division of the areas used for medical purposesinto groups be carried out – generally by the repre-sentative of the purchaser (= planner) together withthe medical and technical staff (= operators). An es-sential basis for the decision regarding which groupa room is allocated to (Table 4.2) is the nature of thecontact between the applied parts of the ME equip-ment and the body of the patient. In areas belongingto group 1, invasive examinations and therapies caneven be performed, but no examinations or therapiescan be performed directly on the heart. A power fail-ure with a maximum duration of 15 s can be dangerous
PartA
4.4
Technical Safety of Electrical Medical Technology Equipment and Systems 4.4 Areas Used for Medical Purposes 41
Table 4.2 Normative criteria for the classification of rooms in groups
Group 0 Group 1 Group 2
Consulting rooms Medical and dental practice rooms Surgery preparation rooms
Surgery consulting rooms Surgical outpatient clinics Operating theaters
Dressing rooms Rooms for home dialysis Recovery rooms
Wards Wards Intensive care units
Massage rooms Rooms for hydrotherapy Special baby care units
Fitness rooms Endoscopy rooms Endoscopy rooms
OT adjoining rooms Rooms for minimally invasive surgery Rooms for minimally invasive surgery
Respiratory chambers Angiography rooms Angiography rooms
Cardiac catheterization laboratories Cardiac catheterization laboratories
(investigation) (investigation and treatment)
CT rooms
Magnetic resonance imaging (MRI) rooms
Electrocardiography (ECG) rooms
Electroencephalography (EEG) rooms
Delivery room
Treatments aredangerous for the
patient. Investigationscannot be repeated.
Area used for medicalpurposes, belonging
to group 0
Area used for medicalpurposes, belonging
to group 1
Area used for medicalpurposes, belonging
to group 2
Application parts of MEequipment are not
used.
The patient is not put atrisk as a result of a firstfault to frame or earth
fault when switching offthe electrical system.
The patient is not put atrisk in the event of
failure of the generalpower supply.
Investigations andtreatments can beinterrupted and
repeated.
Application parts of MEequipment are usedexternally and/or
invasively on any part ofthe body required,except on the heart.
The patient is put at riskin the event of failure of
the general powersupply.
The patient is put atrisk as a result of a firstfault to frame or earth
fault when switching offthe electrical system.
Application parts of MEequipment are used for
applications such asintracardiac procedures
and vital treatments.
Fig. 4.1 Examples of the allocation of rooms to groups
PartA
4.4
42 Part A Medical Technology Basics
in this situation, however. Classification in group 2and the use of a battery-supported power supply forsafety purposes (BPS, previously PS) should thereforebe considered.
In group 2, the criteria applied are intracardiacor open-heart treatments or examinations (in addition,consider DIN 57753-2) and essential examinations and
treatments. The additional description of the electricalconditions in DIN VDE 0100-710 for classification intogroups should help in making the decision (Fig. 4.1).All criteria which are important for the safety of thepatient must always be consulted when selecting thegroup. Where there is any doubt, the decision shouldbe made to choose the higher level of safety [4.2].
4.5 Electrical Systems According to the Natureof the Connection to Earth
Consistent application of the terre neutre séparé (TN-S)system in accordance with DIN VDE 0100-100 andDIN VDE 0100-710 within a building is of fundamentalimportance for the effectiveness and the proper appli-cation of protective measures in the electrical system,in particular of measures to protect against shock cur-rents and against electromagnetic interference (externalvoltages). In this system, the neutral conductor and theprotective earth (PE) are conducted separately in theentire building and are only connected to one anotherat one point, e.g., in the low-voltage main distribution
board. As a result, only fault currents but no operat-ing currents can continue to flow in the protective earth.In normal operation, small, unavoidable fault currentsoccur in the protective earth of the final circuits, in par-ticular small inductively and capacitively induced faultcurrents and those induced by insulation resistances.These currents can be several amps in the protectiveearth of the building’s main distributor. In the case offault to frame or earth faults, relatively high fault cur-rents of up to several kA may briefly occur in finalcircuits until the protective device is triggered [4.2].
4.6 Protection Against Shock Currents
In areas used for medical purposes belonging togroups 1 and 2, according to DIN VDE 0100-710 anagreed limit of the contact voltage (DIN VDE 0100-200) of UL ≤ 25 V applies, which must be observed.Examinations and treatments performed directly on theheart are an exception. A maximum contact voltage of10 mV is applicable in this case, in accordance withDIN 57753 part 2 of 02/1983 (VDE guideline 0753-2part 2/02.83). In the event of a fault, a low value of thiskind cannot be achieved purely by physical means viathe protective earth by means of measures in the electri-cal system. For this reason, ME equipment in protectionclass I can in this case only be operated at the medical ITsystem (DIN VDE 0100-710). The flexible additionalpotential equalization cables must be connected withoutfail. With interventions of this kind, measures must alsobe carried out on the medical side, such as the use ofME equipment with applied parts of insulation class CF.Under the conditions mentioned, risks caused by leak-age currents are extremely unlikely. Leakage currents(Fig. 4.2) and their effects are limited in terms of theelectrical system by the application of the medical ITsystem and by the additional potential equalization.
Protection against the effect of leakage currents isachieved in terms of equipment by using ME equipmentin protection class II and by limiting the patient leakagecurrent (Table 4.3).
The additional potential equalization in every areaused for medical purposes is the most important fun-damental protective measure in the areas used formedical purposes belonging to groups 1 and 2. Inthe areas belonging to group 2, in accordance withDIN VDE 0100-710, additional connector bolts forthe additional potential equalization according to DIN42801 are installed in the patient environment (DINVDE 0100-710, DIN EN 60601-1-1). The flexiblepotential equalization cables to be connected there,which establish an additional direct connection betweenthe PE of the permanently installed system and thehousings of the ME equipment, serve the purposesof
• equalizing potential differences between the MEequipment in the patient environment,• preventing failure of the protective earth in equip-ment in protection class I (first-fault safety), and
PartA
4.6
Technical Safety of Electrical Medical Technology Equipment and Systems 4.6 Protection Against Shock Currents 43
Operator
Patient
Housing leakage current
Exposed metal parts
Mains part Applied partL1 mains
A–aB–a
B–d
C
CC
Patient leakage current
Fig. 4.2 Patient and op-erator connected to MEequipment (after [4.4]).The various equipmentparts form capacitors Cwith the safety-related in-sulation which is situatedbetween them, and the pa-tient leakage current andhousing leakage currentflow via these capacitors.In equipment belongingto protection class I, theearth leakage current alsoflows via the protectiveearth. (A–a Insulationmains part/exposed metalparts, B–a Insulationmains part/applied part,B–d Insulation appliedpart/mains part)
• ensuring that the required contact voltage at thehousing of equipment in protection class I is main-tained.
These cables are of great importance for protect-ing against shock currents and must always beconnected when equipment in protection class I isused [4.2].
Further important protective measures againstshock currents include
1. Protection by automatic disconnection according toDIN VDE 0100-410The electrical circuits of power sockets must be dis-connected by the associated protective device within0.3 s in the event of a fault (zero-impedance shortcircuit). In accordance with DIN VDE 0100-410 of
Table 4.3 Maximum permissible leakage currents fromME equipment according to DIN EN 60601-1
Type Type B Type BF Type CF
Earth leakage 0.5 0.5 0.5
current (mA)
Housing leakage 0.1 0.1 0.1
current (mA)
Patient leakage 0.1 0.1 0.01
current (mA)
2007, this protective measure may only be used forpower sockets of up to 20 A when the power socketis monitored (in this regard see the German govern-ment safety organization regulation BGV A3). In allother situations, 2 shall apply.
2. Protection by automatic disconnection of the powersupply using residual current protective devices(RCD) release current IΔN = 30 mAThis protective measure is prescribed for powersockets in areas in groups 1 and 2 if there is no riskto the patient. ME equipment for vital purposes mustnot be connected here.
3. Protection by notification of insulation faults in themedical IT systemWhere ME equipment is used for vital purposesor for investigations which cannot be repeated, theequipment must be supplied from a medical IT sys-tem. In accordance with DIN VDE 0100-710, powersockets of this type are only installed in areas be-longing to group 2. Here, the medical IT systemconstitutes the preferred protective measure. Owingto the limitation of power in the IT isolating trans-formers to a maximum of 8 kV A, however, it cannotalways be used universally.
The medical IT system forms an isolated and locallyrestricted network. The conductive housing of the ME
PartA
4.6
44 Part A Medical Technology Basics
equipment in protection class I is connected to the pro-tective earth. When only one first fault to frame or earthfault occurs, only the housing leakage current emergesas a fault current and there is no disconnection. Thisensures that a piece of ME equipment which is vitalfor the examination or treatment will not fail and cancontinue to be operated until the treatment is complete.The medical staff are notified of this. Protection againstoverload is not permissible. The overloading of the ITisolating transformer is communicated to the medicalstaff via a monitoring device. The causes of the overload
must be determined and remedied because otherwise theisolating transformer can be destroyed.
The power sockets of the medical IT system mustbe accordingly labeled or designed such that they areunmistakable when several systems are present in oneroom according to the type of earth connection. The in-tention of this is to prevent ME equipment which mustbe supplied from the medical IT system from beinginadvertently connected to power sockets of the TN-S system. There are no normative guidelines for suchcolor coding.
4.7 Power Supply
A safe power supply is another important criterion forsafe operation. The following forms of power supply areavailable for areas used for medical purposes.
• General supply (GS) via a house connection ora high-voltage feed from a distribution system op-erator (DSO);• Power supply for safety purposes (PS) via powergeneration units with internal combustion recipro-cating piston engines;• Battery-supported central power supply for safetypurposes (BPS).
When supplying safety-relevant consumers in areas be-longing to group 2, it is necessary to switch betweenthese power supplies (power sources and mains net-works). The requirements for this switching can befound in DIN VDE 0100-710 under several sections.Considering these normative sources, the followingswitching devices are necessary in the subdistributorsfor the supply to areas in group 2.
• Switching between a PS and GS feed.In this case, the voltage of the outer conductor of thefirst cable (PS) is monitored. If the first cable fails,
continued supply to the consumers mentioned un-der 710.564.4 and 5 must be guaranteed within 15 s,provided this supply is fed from a subdistributor.• Switching between a PS and BPS feed.In this case, the voltage of the outer conductor ofthe first cable (PS) is monitored. If the first cablefails, continued supply to the ME equipment mustbe guaranteed within 0.5 s. If the BPS is used incontinuous operation and the first cable is suppliedwith power from the BPS, the voltage provided isuninterruptible.
The stability and quality of the supply voltage is animportant criterion for a safe power supply. When thestandards for the power socket are observed, in individ-ual cases the nominal voltage of the mains electricitycan deviate by 14% below the nominal voltage. Whensupplying the mains from a power generation unit, inthe case of certain load changes deviations of ±1 Hzfrom the permissible tolerance band for the ME equip-ment are possible. On account of the lower impedanceof the generator compared with mains electricity, har-monic currents can also affect the voltage and lead tointerference. The deviations mentioned can be compen-sated by suitable planning measures [4.2].
4.8 Power Sources for Safety Purposes with Accumulators
In accordance with DIN VDE 0100-710, supply froma BPS with a maximum permissible interruption timeof 0.5 s and a minimum supply period of 1 or 3 h is re-quired for surgical lights. A minimum supply period of3 h is required when only one power generation unit ispresent.
Central BPS units for the supply of ME equipmentare unfortunately not covered by DIN VDE 0100-710.DIN EN 60601-1 requires that ME equipment be de-signed such that an interruption in the power supplydoes not present a hazard before it is restored. On thisbasis, the function of the BPS is in many cases adopted
PartA
4.8
Technical Safety of Electrical Medical Technology Equipment and Systems 4.10 Static Electricity 45
by what are known as internal power sources built intothe ME equipment. There is still demand for centralBPS units, however, as is evidenced by many examples.Some reasons for this are
• a central BPS generates lower costs, in particular inlarge medical institutions, when the high testing andmaintenance costs for the internal power sources(small accumulators) are taken into consideration inaddition to the investment costs,• other indispensable lighting for the operating the-ater lighting (e.g., OT microscopes, endoscopes) areoperated with a 230 V alternating current,• the internal power sources of ME equipment are notsufficiently reliable,
• the internal power sources of ME equipment haveno standby system,• there is ME equipment without internal powersources in circulation,• the central BPS units are required under buildinglaw.
For battery-supported central power supply systems(BPS) for safety purposes for supplying areas usedfor medical purposes, the German national standardDIN VDE 0558-507 has been applicable since October2008.
A uninterruptible power supply (UPS) must not beused to supply ME equipment because it does not meetthe necessary requirements.
4.9 Final Circuits and Plug Sockets
Important requirements for the circuits of plug socketsare mentioned in DIN VDE 0100-710. The plug sock-ets in the patient space must therefore be split betweenat least two circuits. The note includes the requirementthat two medical IT systems must be set up where thereare more than two electrical circuits per patient space. Itis therefore virtually recommended by the standards toset up two medical IT systems per patient space.
When using portable multiple sockets, individu-ally protected electrical circuits are prescribed. For
safety reasons, multiple sockets must not be used,with the exception of wheeled equipment trolleys(Sect. 4.3).
DIN VDE 0100-710 furthermore stipulates that allpower sockets which supply ME equipment must beequipped with an optical voltage indicator. As a result,the medical personnel will immediately be able to rec-ognize which power sockets are still carrying voltagefollowing a fault.
4.10 Static Electricity
Static charges are dependent on the conductivity andseparation speed of the materials involved. Conductivesubstances are those solid or liquid substances whosespecific resistance is up to 104 Ω/m. Nonconductivesubstances on the other hand have specific resistance ofmore than 104 Ω/m. Particularly in the field of surgery,where there is a large amount of medical technologyequipment, and anesthetic gases as well as combustibleliquids such as disinfectants are used, an electrostaticdischarge could ignite the explosive OT atmosphere,with devastating consequences. The following protec-tive measures are therefore necessary in rooms usedfor medical purposes which have areas with potentiallyexplosive atmospheres [4.5].
• Work clothes and also sheets and blankets must bemade of a blended fabric consisting of at least 30%
natural cotton or viscose (without a resin finish).Rubber blankets, mattresses, and pillows must bemade or covered with conductive rubber.• The leakage resistance of the flooring may be107 –108 Ω. To achieve a certain standard insula-tion, the flooring leakage resistance should not fallbelow 5 × 104 Ω.• Equipment and furnishings which are exposed andare conductive must be conductively connectedboth to one another and to the floor. The floor-ing should be electrostatically conductive and atthe same time connected to the potential equaliza-tion. Because explosive, volatile anesthetics suchas halothane or enflurane are no longer available,a controversial discussion has arisen about theneed to equip operating theaters with expensivestatic-dissipative flooring. Nevertheless, according
PartA
4.1
0
46 Part A Medical Technology Basics
to experts, the problem of static charge remainsand can negatively influence or even damage medi-cal technology equipment (e.g., monitoring), whichmeans that it is still sensible to keep the floordissipative.• Operating table systems must be connected to thepotential equalization conductor or protective earth.The tabletop pad must be electrically conductiveso that any electricity generated as a result of fric-
tion can be discharged via the earthed table withoutsparking.• Conductive footwear (including overshoes) musthave a leakage resistance of at least 5 × 104 Ω.• Breathing bags of inhalational anesthetic equip-ment and oxygen ventilation equipment must onlybe manufactured from conductive material. Elec-trically conductive latex mixtures or polypropyleneare particularly suitable for this purpose.
4.11 Electromagnetic Compatibility
A very high level of electromagnetic compatibility(EMC) is required in ME equipment and ME systems toensure the proper functioning of other electrical devices.IEC 50-161 gives the definition for EMC [4.7].
Magnetic and electrical interference fields can im-pair or prevent the safe operation of medical technologyequipment and systems. Interference radiated or con-ducted from the environment can on the one hand affectmedical technology electrical devices, but can also orig-inate from such devices. One example of a radiatedinterference variable is electrosurgery or radiofrequency(RF) surgery. The construction of an RF generator(frequency spectrum 0.4–5 MHz) is in principle com-parable to a transmitter; all that is missing are electroniccomponents for the transmission of information and anantenna. A high proportion of the radiofrequency en-ergy of the RF generator is radiated wirelessly fromthe cables into the environment, especially in the caseof relatively old equipment. Further interference occurswhen electrical cables are conducted parallel to the ca-bles of the RF generator, because stray currents arise inthe electrical supply cables of neighboring equipmentas a result of capacitive and inductive coupling. To en-sure the smooth operation of electromedical equipmentand systems it is also necessary for the required mainsvoltage to be electromagnetically compatible, i. e., forthe effective value to be stable within prescribed lim-its and the level of interference in the voltage to be lessthan the level of compatibility of the equipment beingoperated (EMC environment class 1 and/or 2). Majorconduction-related parasitic inductions are caused bywhat are known as interference phenomena, such as
• fluctuations in the voltage and periodic voltage fluc-tuations as a result of quick load changes in thesupply network (flicker),• harmonics and interharmonics,
• voltage drops and short interruptions,• transient overvoltages,• imbalances,• fluctuations in the mains frequency.
As the number and use of pieces of ME equipmentincrease, there is also a proportional increase in theproblems with electromagnetic compatibility, which isultimately a synonym for concepts including overvolt-age, RF noise, 50 Hz mains hum, earth loops, and circuitfeedback (Table 4.4).
The following EMC features are of particular inter-est for electromedical equipment [4.8].
• In the case of life-sustaining and life-supportingmedical technology equipment and systems, correctoperation without any impairment must be ensured.• In the case of medical technology equipment andsystems which are not for life-sustaining purposes,impairment may occur which is not relevant tosafety and can be recognized by the operator.
Table 4.4 Reference values for interference parameters(after [4.6])
Interference variable Unit Reference value
Frequency range [Hz] 0–1010
Voltage [V] 10−6 –106
Voltage variation [V/s] up to 1011
Current [A] 10−9 –105
Current variation [A/s] up to 1011
Field strength, electrical [V/m] up to 105
Field strength, magnetic [A/m] 10−6 –108
Power [W] 10−9 –109
Pulse energy [J] 10−9 –107
Pulses Rise time [s] 10−10 –10−2
Duration [s] 10−8 –10
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Technical Safety of Electrical Medical Technology Equipment and Systems References 47
• Equipment with various functions which are di-rectly connected to the patient must operate reliably,without any mutual interference.• Specific requirements apply for the operating the-ater area.• There are special interference-suppression conceptsregarding leakage currents (e.g., housing leakagecurrent).
To guarantee electromagnetic compatibility in med-ical technology, the following technical and organiza-tional measures are available, among others [4.9].
1. For direct safety, grounding, potential equalization,shielding, filtering, protection against overvoltage,selection of cables, and circuit layouts suitable forEMC are all possibilities.
2. Indirect safety is achieved by spatial measures,signal conversion of the usage variables, use ofinterference-free software, and installation of alerttechnologies.
3. Administrative safety is achieved by measuressuch as a code of conduct, EMC planning,repair, maintenance, and servicing, among oth-ers.
4.12 Conclusions
The primary requirements for ME equipment and theelectrical system in areas used for medical purposesare based on a safe power supply, protection againstshock currents and magnetic or electrical interference,and protection against the risk of explosion and fire.
When dealing with ME equipment in the clinicalenvironment, it is inevitable that each operator will
become familiar with the functioning and intended pur-pose of the electromedical equipment and with thepossible combinations with ME systems. In addition,monitoring of the condition of the equipment, the ac-cessories, and the cable lines and function checking ofthe ME equipment and ME systems are also crucial forsafe operation.
References
4.1 B. Schneider: Aufgabe und Arbeitsweise der
Fachkräfte für Arbeitssicherheit. In: Grundlehrgang
A für Sicherheitsfachkräfte, Vol. II, ed. by Bundes-
anstalt für Arbeitsschutz (TÜV, Cologne 1976)
4.2 H.-P. Uhlig, N. Sudkamp: Elektrische Anlagen in
medizinischen Einrichtungen (Hüthig Pflaum, Hei-
delberg 2004)
4.3 ISO Guide 51: Guidelines for inclusion of safety as-
pects in standards (Beuth, Berlin 1990)
4.4 T. Flügel, W. Linke, E. Möller, H.-J. Slisch-
ka, K. Tillmanns: Starkstromanlagen in medi-
zinisch genutzten Gebäuden mit stationären oder
ambulanten Bereichen, 3rd edn. (VDE, Berlin
2004)
4.5 W. Twachtmann: Sichere Stromversorgung im
Krankenhaus, Krankenh. Tech. 1, 42–44 (1992)
4.6 H.G. Meyer: Elektromagnetische Verträglichkeit. In:
Biomedizinische Technik, Medizinische Sonderge-
biete, Vol. 4, ed. by H. Hutten (Springer/TÜV, Berlin
Heidelberg 1991) pp. 301–339
4.7 IEC 50-161: International Electrotechnical Vocabulary
(IEV), Electromagnetic Compatibility (Beuth, Berlin
1990), Chap. 161
4.8 R. Sitzmann: Elektromagnetische Verträglichkeit in
der Medizintechnik, Electromedica 2, 84–86 (1998)
4.9 C. Hartung: Szenario elektromagnetischer Störungen
am Beispiel der Medizintechnik im Krankenhaus, mt
5, 172–177 (1999)
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49
Quality Mana5. Quality Management in Medical Technology
Albrecht Malkmus
This chapter aims to provide a basic under-
standing about the objectives, elements, and
structure of a quality management system in
the field of medical technology. It will show
the elements and the organization of a qual-
ity management system. Practical guidance is
given for setting up a quality management
system.
5.1 Objectivesof a Quality Management System ........... 495.1.1 Concepts ..................................... 495.1.2 Objectives and Clientele of a QMS ... 505.1.3 Regulatory Requirements .............. 50
5.2 Elementsof a Quality Management System ........... 54
5.3 Organizationof a Quality Management System ........... 54
5.4 Implementation of a QMS ...................... 565.4.1 The QMS and the (End) Customers ... 565.4.2 The QMS and the Management....... 565.4.3 The QMS and the Employees .......... 565.4.4 The QMS and Satisfaction
of the Regulatory Requirements ..... 56
5.5 Product Quality .................................... 57
5.6 Concluding Remarks ............................. 57
References .................................................. 58
5.1 Objectives of a Quality Management System
5.1.1 Concepts
What exactly is a quality management system, and whatdoes it achieve?
The standard EN ISO 9000:2008 gives the followinganswers to this question:
• A quality management system is a management sys-tem to direct and control an organization with regardto quality.• Quality is the degree to which a set of inherent char-acteristics fulfils requirements.
Expressed in rather more everyday language, thismeans that, with the help of a quality management sys-tem (QMS), the relevant processes in an organizationare designed and controlled such that the finished prod-ucts or services rendered satisfy the requirements of thecustomers to the highest possible degree.
According to this understanding, other managementactivities such as finance management or environmentalmanagement are not part of quality management (QM)– unless the quality of the products and services would
be directly affected by these management systems. Allof a company’s customer-based and value-adding pro-cesses are accordingly the subject of QM:
• Marketing and sales• Development, procurement, and production• Delivery, installation, and maintenance.
A particular feature of medical technology is thecomprehensive regulatory guidelines, that is to say thelegal requirements which are attached to the marketingand operation of medical devices. Since these require-ments have an impact on virtually all product realizationprocesses, it makes sense in the field of medical technol-ogy to regard the systematic fulfilment of the regulatoryrequirements (regulatory affairs) as part of QM.
Another feature is the critical nature of medical de-vices: The consequent minimization of risks for thepatient, user, and third parties during development, pro-duction, installation, and use of a medical device mustbe pursued with a dedicated risk management process.
Because the requirement for safe medical devices ispart of the essential customer requirements, the techni-
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50 Part A Medical Technology Basics
cal risk management must also be an integral part ofQM.
Quality Costs
Another concept which is important in understandingQM is the idea of quality costs. Quality costs are under-stood as being the sum of the following cost groups:
• Prevention costsAll endeavors which are undertaken to preventfaults from emerging: implementation of a QMS,internal audits, staff training, identifying cus-tomer requirements, designing the infrastructureand working environment, etc.• Appraisal costsAll endeavors which are undertaken to detect faults:verification and validation of products and pro-cesses.• Nonconformity costsAll endeavors which are undertaken to remedyfaults and their consequences: reworking, warrantycosts, etc.• External quality assurance costsAll endeavors which are undertaken to demonstrateto third parties the existence of an effective QMS:certifications and product approvals, demonstrationof the QMS to customers, etc.
5.1.2 Objectives and Clientele of a QMS
Why do businesses with high costs implement a QMS?The increase in the competitiveness of the company isthe intrinsic motivation for implementing a QMS. Thismeans:
• Realizing the products and services such that theyfulfil the requirements of the customers as best pos-sible• Introducing new products onto the desired marketsin as short a time as possible, while fulfilling allapplicable regulatory requirements• Minimizing the quality costs while maintaininga given level of quality.
The numerous regulatory requirements and the re-quirements of the market are the extrinsic motivation:
• An effective QMS is required by law as a prerequi-site for marketing medical devices. The existence ofan effective QMS is checked by independent certifi-cation authorities (notified bodies).
• The customers in the business-to-business sector(B2B) and also large end customers will only acceptsuppliers which have a certified QMS.• The liability risk of the manufacturer within thescope of product liability can be reduced by an ap-propriate design of the QMS. A checklist coveringthese points can be found in a handbook providedby the DIHK (Deutscher Industrie- und Handels-kammertag, German Association of Chambers ofIndustry and Commerce) [5.1].
As a result of these different objectives for a QMS,a QMS must also serve different customer groups.
The diagram in Fig. 5.1 shows the most importantcustomer groups for a QMS in medical technology.
5.1.3 Regulatory Requirements
The numerous regulatory requirements in the field ofmedical technology relate to:
• The product realization processes and the manufac-turer itself• The products manufactured and the services ren-dered, as well as• The marketing, installation, operation, and mainte-nance of medical devices.
These regulatory requirements therefore have a di-rect impact on the processes of the company which fallwithin the domain of QM and must therefore be takeninto consideration when setting up a QMS. Table 5.1gives an overview of the applicable requirements in themost important medical technology markets.
In addition to the directives, numerous guidelineshave also been created for the European Union (EU) ina consensus between authorities and manufacturers ofmedical devices, so-called MEDDEVs, which representa general interpretation of legal requirements. Theseguidelines deal with different issues, from definitionsof concepts, through general and specific production re-quirements, to market observation. A complete list ofthe MEDDEVs can be found on the Internet pages ofthe European Commission [5.2].
In the case of the European Union, the national lawsmust also be taken into account, which arise as a resultof the translation of European law into national law.
Those which are applicable for Germany are thoseshown in Table 5.2.
In addition to the European directives and guide-lines and the national laws, the approval of medical
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Quality Management in Medical Technology 5.1 Objectives of a Quality Management System 51
Customer(end customer, B2B)
QMS certificate,declaration of conformity,
quality certificates
Requirements,market observation
Requirements
Declarationof conformity
QMS certificate,evidence
Qualityagreement
QMSin
medicaltechnology
QMScertificate
Reports
Evidence
Guide-lines
Qualityperformance
figures
QMS certificate, risk management
Legislating body
Notified body
Authorities
Court
Insurer
Supplier
Employee Evidence
Qualitygoals
Companymanagement
Fig. 5.1 Customer groups for a QMS in medical technology
devices in the European economic zone is predomi-nantly based on harmonized standards:
• Harmonized standards are developed by the Eu-ropean standardization bodies CEN (Comite Eu-ropeen de Normalisation, Europeaan Committee forStandardization), CENELEC (European Commit-tee for Electrotechnical Standardization), and ETSI(European Telecommunications Standards Institute)with the aim of specifying the requirements of theCE directives.• Harmonized standards adapt the requirements to theEU member states. When a harmonized standard issatisfied, it is assumed that the requirements of thecorresponding CE directive on which it is based willbe satisfied.• The implementation of (harmonized) standards isnot compulsory. However, the manufacturer must
then demonstrate in some other way that the under-lying requirements are satisfied.• The harmonized standards include standards forquality management models such as EN ISO 13485,standards regarding general safety, and standardsregarding the safety and effectiveness of specificproduct groups or products.
A complete list of the harmonized standards in thefield of medical devices is provided by the EuropeanCommission on the Internet (http://www.newapproach.org/Directives/DirectiveList.asp). The European Direc-tives for medical devices distinguish between differentdevelopment stages of a quality management system:
• Complete quality management system.The QMS includes the areas of design, manufacture,and final checking of the products in question.
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52 Part A Medical Technology Basics
Table 5.1 International regulatory requirements in medical technology
Economic zone Applicable requirements Authority/link
European Union directives 93/42/EEC Medical device directive (1993)90/385/EEC Active implantable medical devices (1990)98/79/EC In vitro diagnostic medical devices (1998)
National authorities in GermanyBundesinstitut für Arzneimittelund Medizinprodukte (BfArM):http://www.bfarm.de/Deutsches Institut für MedizinischeDokumentation und Information(DIMDI): http://www.dimdi.de/
USA 21 CFR Part 820 Quality system regulation21 CFR Part 11 Electronic records21 CFR Parts 800–1299 Medical devices
Federal Drug Administration (FDA)http://www.fda.gov/
Canada Medical devices regulations Health Canada:http://www.hc-sc.gc.ca/
Japan New Japanese pharmaceutical affairs law (PAL; 2005) Ministry of Health, Labor andWelfare (MHLW), Pharmaceuticalsand Medical Devices Agency(PDMA): http://www.mhlw.go.jp/
China China compulsory certificate (CCC) Certification and AccreditationAdministration of the PeoplesRepublic of China (CNCA), ChinaQuality Certification Centre (CQC):http://www.cnca.gov.cn/
Table 5.2 Further regulatory requirements in Germany in the field of medical technology
Law Applies to
MPG Medical Devices Act; 2002/2007/2009 (Medizinproduktegesetz) Manufacturer and productMPV Ordinance on Medical Devices; 2001/2004 (Medizinprodukteverordnung) Manufacturer and productMPSV Ordinance on Medical Devices Safety Planning; 2003
(Medizinprodukte-Sicherheitsplanverordnung)Manufacturer, operator
MPBetreibV Medical Devices Operator Ordinance; 2003(Medizinprodukte-Betreiberverordnung)
Manufacturer, operator
MPVertrV Ordinance on Medical Devices Marketing Channels; 1997/2001/2003(Medizinprodukte-Vertriebswegeverordnung)
Manufacturer
MPVerschrV Ordinance on the Prescription Requirement for Medical Devices; 2002(Verschreibungspflicht von Medizinprodukten)
Manufacturer, operator
DIMDIV Ordinance on Database-Assisted Information Systems Concerning Medical Devices(Verordnung Datenbankgestütztes Informationssystem über Medizinprodukte)
Manufacturer, operator
• Quality management system production.The QMS only includes the areas of manufactureand final checking of the products in question.• Quality management system product.The QMS only includes the final checking of theproducts in question.
With the lower development stages of the QMS,depending on the critical nature of the product, product-related tests must be carried out by a notified body –process steps which under certain circumstances canlead to sensitive delays in market introduction. Becausethe international requirements moreover do not makethese distinctions, it can only be recommended thata complete QMS be implemented.
The requirements for a QMS in the field of medicaltechnology are specified in the following standards.
• EN ISO 13485:2009. Medical devices – Qualitymanagement systems – Requirements for regulatorypurposes.• EN ISO 14971:2008. Medical devices – Applicationof risk management to medical devices.
Whoever is certified according to ISO 13485:2009satisfies the European legal requirements for a QMS. Inaddition, compliance with ISO 13485 and ISO 14971also for the most part means satisfaction of the inter-national requirements (USA, Japan, Canada, etc.) fora QMS.
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Quality Management in Medical Technology 5.1 Objectives of a Quality Management System 53
Table 5.3 The most important QM elements according to ISO 13485
Responsibility of the managementand quality management officer
Quality management is the responsibility of the company man-agement.It is the responsibility of the company management to ensurethe implementation and maintenance of a QMS and to regularlycheck its effectiveness.A member of the company management (management rep-resentative) must be nominated who has responsibility andauthorization for the implementation and maintenance of theQMS and who informs the management about quality mattersin the company.
Quality policy and quality goals The responsibilities of the company management also includethe obligation of the company to document quality in a qualitypolicy and to form concrete quality goals from this policy.
Document management Document management, which is to say the creation, release, dis-tribution, and updating of specifications and quality certificates,must be provided in written form. The standard also stipulateswhat content must be documented.
Human resources The employees whose work can influence the product qualitymust be adequately qualified for their jobs.
Infrastructure and working environment The company must design the infrastructure and the working en-vironment such that the required product properties are achieved.Examples of this include suitable premises, machines, and toolsor environmental conditions, such as the atmospheric humidity,temperature, etc.
Product realizationPlanning of all the necessary processeswithin the scope of product realization(including risk management)Ascertainment of customer requirementsDefine product development processesDefine procurement processesDefine production processesDefine processes for delivery, installation,and maintenance
All product realization processes must be planned and docu-mented.The process chain under consideration ranges from marketingand sales (ascertaining customer requirements) to service in thefield (maintenance and market observation).The standard stipulates at what points in the process chain checksmust be performed.The (technical) risk management must be integrated in thisprocess chain in the same way as the verifiable fulfilment ofall regulatory requirements (conformity to standards, productapprovals).
Measurement, analysis, and improvement Setting up meaningful and valid performance measurement sys-tems which provide information about the conformity of theproduct and the conformity and effectiveness of the QMS.The spectrum of the performance figures covers both technicalprocess parameters and performance figures concerning cus-tomer satisfaction.Setting up effective improvement processes which make the nec-essary corrective and preventive measures possible.
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54 Part A Medical Technology Basics
Note: ISO 13485:2009 is based on ISO 9001:2008,which is not industry specific. Allowance must be madefor the fact that ISO 13485 has not adopted all of the
requirements of ISO 9001. Organizations which arecertified according to ISO 13485 therefore do not au-tomatically meet the requirements of ISO 9001.
5.2 Elements of a Quality Management System
The requirements for a QMS in the field of medicaltechnology are defined in detail in ISO 13845. In caseof any questions, the following standards can be used:
• DIN EN ISO 9000:2005 (Concepts)• DIN EN ISO 9004:2000• ISO/TR 14969 (Guidelines).
Table 5.3 aims to give a brief overview of the es-sential elements of a QMS according to ISO 13485:The last element “Measurement, analysis, and improve-ment” in particular represents a principle which formsthe basis of all QM models, the plan–do–check–act(PDCA) cycle by Deming [5.3], a cycle for continuousimprovements (Fig. 5.2):
Plan: Analysis of the current situation, determina-tion of the new quality goals, specification ofthe new processes
Do: Implementation of the new processesCheck: Checking to ascertain whether the planned
goals are being achieved
Act Do
Check
Plan
Fig. 5.2 ThePDCA cycle byDeming [5.3],a cycle forcontinuous im-provements
Act: Transfer the new processes into the routine andimplement countermeasures in the event of de-viations.
This cycle is followed continuously for the purposeof constant improvement and is a closed control loop.
The challenge when setting up a QMS is to integratethe principle of the PDCA cycle into all elements ofthe QMS and thus to create an active and self-adaptingQMS.
5.3 Organization of a Quality Management System
If the field of application and the elements of the QMShave already been prescribed in detail by means of theEuropean directives and ISO 13485, then there is a greatdeal of room for maneuver in the organization of theQMS. The spectrum of the possible forms of organi-zation ranges from a large, central QM department,which is responsible for all QM duties, to delegationof the QM duties to all management staff and employ-ees and to complete abandonment of a separate QMorganization.
Three principles have proved to be of value in prac-tice and are consistent with the applicable requirements:
1. Direct feeding or integration of QM into companymanagement
2. Preferably process-oriented responsibility for theindividual elements of the QMS
3. Guarantee the independence of all testing authori-ties.
These principles can lead to the following organiza-tional model:
• A separate organizational unit is formed which is re-sponsible and authorized for all superior (company-wide) QM issues.• This central QM position is a member of the corpo-rate management or is directly below the corporatemanagement.• In all functional areas of the company which are thesubject of QM, one or more employees are assignedQM tasks. Depending on the size of the functionalarea, they take on the QM tasks either in addition toother assignments or on a full-time basis. Within thescope of their QM tasks, they report professionallyto the superior QM position.• All employees who perform checks do not belong tothe organizational unit whose processes or productsthey check.
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Quality Management in Medical Technology 5.3 Organization of a Quality Management System 55
Table 5.4 Organization of quality management
Superior QM QM representative of a functional area
Formulation of the company-wide quality goals in co-ordination with the company management
Formulation of the area-specific quality goals in coor-dination with the area management and the superiorQM position
Implementation and adjustment of a company-wideperformance measurement system
Determination of the performance figures for the func-tional area
Preparation of the annual management appraisal Provision of the necessary information
Identification of the applicable legal and normative re-quirements and communication of these requirementsin the company
Adaptation of the processes in the functional area tothe applicable requirements
Coordination/performance of QM trainingprogrammes
Performance of QM training in the functional area
Implementation and maintenance of the company-wide QM handbook
Implementation and maintenance of all sections of theQM handbook which concern the functional area
Implementation and maintenance of a superior proce-dure model for product realization
Implementation and maintenance of all steps of theprocedure model which concern the functional area
Coordination of external quality audits and certifica-tions
Preparation and provision of the necessary documentsand points of contact
Coordination/performance of internal quality audits Preparation and provision of the necessary documentsand points of contact; if necessary, involvement in theaudit
Monitoring of superior corrective and preventive mea-sures
Monitoring of area-specific corrective and preventivemeasures
Performance of product approvals Provision of the necessary documents
Contact with authorities as part of the notification obli-gation
Provision of the necessary information
In the model above, the tasks would be distributedas shown in Table 5.4. The representation of Ta-ble 5.4 does not show the processing of customercomplaints, investigation into customer satisfaction orproduct observation in the field. These activities canbe sensibly integrated into the superior QM positionand into service or sales. Demonstration of conformityof the products with technical standards is likewisenot included. According to the principle of process-oriented responsibility, it is recommended that these
tasks be integrated into product development. The num-ber of employees who are assigned QM tasks is ofcourse dependent on the size of the company andthe complexity of the products. In very small compa-nies, all of the activities described above could alsobe undertaken by one employee in simultaneously heldpositions.
Last but not least, the principles of effective man-agement should of course also be observed in thestructuring of a QMS [5.4].
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56 Part A Medical Technology Basics
5.4 Implementation of a QMS
As in the organizational implementation, there is alsoa large degree of freedom in the technical implementa-tion of a QMS. When implementing a QMS, the variouscustomer groups of the QMS should be consideredagain (Sect. 5.1.2).
5.4.1 The QMS and the (End) Customers
The (end) customer is the reason for the existence ofthe company and the QMS. It is important that the cus-tomer is actually also integrated into the processes of theQMS as a real person. This should be done not merelyreactively as part of the processing of complaints butalso proactively, for example, through cooperation inthe development of new products and services.
5.4.2 The QMS and the Management
The management of the company is the key customergroup of the QMS. For the management, the QMS mustrepresent a reliable instrument for managing the com-pany. As mentioned in Concept of a QMS (Sect. 5.1.1)to the management the QMS is just one of manymanagement systems. To create an easily understand-able and manageable basis for decision-making forthe company management, the most important perfor-mance figures from the QMS should be integrated withthe most important performance figures from the othermanagement systems to form a common instrument.
One suitable approach to this is the balanced score-card performance and management system [5.5].
A balanced scorecard combines at least the follow-ing four perspectives of a company:
1. The financial perspective2. The customer perspective3. The internal processes perspective4. The learning and development perspective.
With the help of these four perspectives, both retro-spective and prospective performance figures are usedto manage the company. The performance figures forthe QMS fall under the customer perspective in partic-ular, but also the internal processes perspective and thelearning and development perspective.
5.4.3 The QMS and the Employees
The employees are numerically the largest customergroup of a QMS. If their requirements are not met, the
guidelines of a QMS do not become a valued resourcebut rather an unpopular burden. The regulations of theQMS should not only satisfy the regulatory require-ments but should also represent valuable tools for theemployee.
This results in the following requirements for theQMS.
• The structure of the quality management manualshould be orientated towards the processes in thecompany, and not towards the structure of a stan-dard.• Specifications (process descriptions, work instruc-tions, etc.) should be written for the respective targetgroup in an easily comprehensible form and shouldcontain implementable instructions. For each pro-cess step, the required results should be defined incontent and structure.• All specifications should be integrated into the re-spective working environment, and it should bepossible to find them quickly and intuitively.• It is recommended that a structured proceduremodel be defined for product realization and that thenecessary results be reported for each process step.
This structured procedure model is ideally imple-mented as an electronic workflow. This workflow isused for implementation of the QMS as well as forproject management. Note: In the case of a paperlessworkflow, the international regulatory requirements forelectronic signatures must be observed (see, for exam-ple, [5.6]):
• All process steps of the QMS should regularly bechecked for their effectiveness, their efficiency, andthe reason for their existence.• Checking of the acceptance of the QMS by theemployees should be incorporated in the QMS asa fixed component.
5.4.4 The QMS and Satisfactionof the Regulatory Requirements
The implementation of a QMS should take into consid-eration the regulatory requirements of all countries inwhich the products will be marketed. A decision mustalso be made regarding the language in which the doc-uments of the QMS and the product-related documents,such as specifications, design documents or test certifi-cates, will be written. To be able to present the QMS
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Quality Management in Medical Technology 5.6 Concluding Remarks 57
externally with little effort or cost, it is a good idea tocreate associations between the QMS documents andthe product-related documents on the one hand and thevarious national and international requirements on theother hand.
Ideally, these associations are managed in a databaseand are integrated directly into the electronic documentmanagement system and into the electronic workflow
of product realization. All necessary regulatory per-spectives can then be generated from the database ondemand, and the proof of conformity for the QMS andfor the products can thus be provided with little effort orcost. Conversely, the electronic workflow can automati-cally compile the respective process steps necessary andproduct-related documents on the basis of the informa-tion for the planned markets.
5.5 Product Quality
Table 5.5 Product requirements of various parties in different lifecycle phases
Lifecycle phase Distributor Buyer/ User Patient Technical Health Notified Legislatingoperator service insurance body body/
authority
Product realization × × × ×
Marketing × × × ×
Commissioning × × × × ×
Operation × × × × × ×
Maintenance × × × ×
Reprocessing × × ×
Decommissioning ×
Scrapping × ×
Following the discussion of the objectives and the im-plementation of quality management systems, the actualsubject of a QMS should still be taken into considera-tion: the quality of the products manufactured. What isimportant here is that consideration should not only begiven to the requirements of patient and user during op-eration of the product, but also that the manufacturertakes into account the requirements of all relevant par-ties over the entire lifecycle of the product. Table 5.5illustrates which parties place requirements on the prod-uct in which phase of its lifecycle.
The scope of the requirements and the signifi-cance of the individual lifecycle phases are dependent
on the nature and complexity of the medical de-vice: nonactive or active medical device, instrument orcomputer-assisted device, individual product or systemcomponent, disposable product or reusable equipment,etc.
The QMS of the manufacturer of the medical devicemust therefore be designed such that the requirementsof all parties for a product in the various lifecycle phasesare determined at the beginning of the product realiza-tion phase and are adequately satisfied. Only in this wayis it possible to guarantee that the customer receivesa product which complies with their requirements overits entire lifecycle.
5.6 Concluding Remarks
The principle of QM – to systematically ensure thatthe requirements of the customers are met – must al-ways also be adapted to the QMS itself. In a continuousprocess of reflection, or rather in a continuous plan–do–check–act cycle, checks must continuously be carriedout to determine:
• Whether the QMS effectively establishes the rele-vant requirements for the product and ensures theserequirements are met• Whether the balance is maintained between(a) helpful guidelines and unnecessary regi-mentation, (b) important evidence and superflu-
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58 Part A Medical Technology Basics
ous paper, and (c) customer-orientated optimiza-tion of products and mere conformity with theQMS.
The instrument of management appraisal, as re-quired in Sect. 5.6 of ISO 13485, can performthis reflection process and maintain the balance bycarefully testing and evaluating to what degree theQMS satisfies the requirements of its many cus-tomers.
In the face of strong regulatory pressure, many com-panies tend to forget the intrinsic motivation for theQMS and neglect the employees and the company man-agement as customers of the QMS. This would meanthrowing away valuable potential, however a QMSshould never be pursued solely to meet external re-quirements but should always be used to increase thecompetitiveness of a company.
Further Reading• ISO: DIN EN ISO 9000:2005-12 Quality manage-ment systems – Fundamentals and vocabulary (ISO2005)• ISO: DIN EN ISO 9001:2000-09 Quality manage-ment systems – Requirements (ISO 2000)• ISO: DIN EN ISO 9004:2000-12 Quality manage-ment systems – Managing for the sustained successof an organization (ISO 2000)• ISO: DIN EN ISO 13485:2009-07 Medical devices– Quality management systems – Requirements forregulatory purposes (ISO 2003)• ISO: DIN EN ISO 14971:2007-07 Medical devices– Application of risk management to medical de-vices (ISO 2007)• ISO: ISO/TR 14969:2005-10 Medical devices –Quality management systems – Guidance on the ap-plication of ISO 13485:2003 (ISO/TR 2005)
References
5.1 DIHK: Produkthaftung – Ein Leitfaden für Hersteller,
Zulieferer, Importeure und Händler (DIHK, Bonn
2008)
5.2 European Commission, Enterprise and Indus-
tries, Healthcare Industries, Referenced Documents:
http://ec.europa.eu/enterprise/sectors/medical-
devices/documents/guidelines/ (European Commis-
sion, Brussels 2010)
5.3 W.E. Deming: Out of the Crisis (Massachusetts Insti-
tute of Technology, Cambridge 1982) p. 88
5.4 F. Malik: Führen, Leisten, Leben. Wirksames Man-
agement für eine neue Zeit (Heyne, München
2001)
5.5 R.S. Kaplan, D.P. Norton: Balanced Scorecard –
Strategien erfolgreich umsetzen (Schäffer-Poeschel,
Stuttgart 1997)
5.6 US Government: Code of Federal Regulations, Title 21
Food and Drugs, Chapter I, Part 11 Electronic Records,
Electronic Signatures (US Government Printing Office,
Washington 2005)
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