poster 356: test results showing bench reliability on catheter dislodgement for ascenda, medtronic...

unit. She started rehabilitation therapy with toe touch weightbearing (TTWB) precautions to her right lower extremity.Patient was alert, oriented, and actively participating in ther-apies. Low molecular weight heparin was used for deep veinthrombosis prophylaxis.Setting: Acute rehabilitation unit.Results: Patient developed a right hip hematoma with pu-rulent discharge during hospitalization. Wound culture wasnegative, and no leukocytosis was present. A computed to-mography scan with intravenous contrast of her right hip wasrequested for further evaluation. Patient denied history ofallergies and reported she had a previous contrast study inthe past without any complications. After administration ofthe nonionic contrast solution intravenously, patient imme-diately reported some chest discomfort and shortness ofbreath. The patient became unresponsive, and seizure-likeactivity was witnessed. Initial resuscitation methods wereperformed until it was confirmed that the patient had a “donot resuscitate” (DNR) order. Patient was in cardiac asystole.An autopsy revealed evidence of cardiac disease as well aslaryngeal edema.Discussion: Fatal anaphylactoid reactions are rare but haveoccurred with both ionic and nonionic contrast agents. Lim-ited studies have reported sudden cardiopulmonary arrestimmediately after nonionic contrast medium administration.The risk of common and serious adverse effects has beenreduced with the use of nonionic contrast agents.Conclusions: Anaphylaxis after administration of intrave-nous contrast media is a major concern. Physiatrists shouldbe aware of this lethal complication because studies withintravenous contrast are frequently ordered. It is important torecognize signs and symptoms of anaphylactic reactions andtreat immediately.

Poster 356Test Results Showing Bench Reliability onCatheter Dislodgement for Ascenda,Medtronic Neuromodulation’s Next-Generation Catheter.Karl Hokanson, BSME, MSME (Medtronic Inc, Min-neapolis, MN); Amy Gjoraas; Julie Kopp; MichaelMetzler; Andrew Servi.

Disclosures: K. Hokanson, Medtronic Inc, Employment.Patients or Programs: A next-generation catheter(Ascenda™) was recently developed for a programmable,implanted infusion system that administers drugs to theintrathecal space. Our program evaluated several knownfailure modes for catheter dislodgement, which can occureven when an anchor is sutured to the site where the catheterexits the fascia. The catheter can migrate distal to the anchordue to a “sweeping motion” between skin and fascia, orproximal to the anchor due to tensile forces from bodymotion.Program Description: To evaluate catheter dislodge-

ment due to a “sweeping motion” between the skin andfascia, an anchored catheter was exposed to oscillatory forceof 0.70 lbf, perpendicular to the catheter axis. The anchoredcatheter was exposed to this force for a minimum of 120,450cycles, based on a study that evaluated activities of dailyliving and the number of cycles these activities could impartin 1 year (the time frame within which dislodgement distal tothe anchor is expected to occur). To evaluate catheter migra-tion and cyclic axial fatigue performance due to tensilestresses from body motion proximal to the anchor, the cath-eter anchor was exposed to a cyclic axial fatigue test for aminimum of 850,000 cycles at a displacement of 0.27” (de-rived from human studies that evaluated the maximum dis-placement of the catheter due to activities of daily living).Setting: Medical device manufacturer laboratory.Results: During attempted dislodgement, the catheter with-stood 250,000 cycles (more than twice the requirement)without displacement of the anchor. During tensile cyclicfatigue exposure, the catheter withstood 1,700,000 cycles(twice the requirement) without catheter movement relativeto the anchor.Discussion: These bench test results illustrate the robust-ness of the catheter with respect to dislodgement, above andbeyond established design requirements.Conclusions: When considered collectively, these resultsprovide evidence of a highly reliable and robust catheterdesign.

PROSTHETICS, ORTHOTICS, ASSISTIVEDEVICES

Poster 357Effect of Weight of PTB Prosthesis in the Gait ofTranstibial Amputee By Using CDG GaitAnalyzer.Priyadarshini C. Subramaniam, MBBS, DPMRDNB(PMR) (Stanley Medical College, Chennai, India);Ratnesh Kumar, MBBS, MS, DNB (PMR).

Disclosures: P. C. Subramaniam, None.Objective: The purpose of the study is to identify thekinematic characteristic and temporal parameters in the gaitof transtibial amputee with different prosthetic weights andthereby determine the optimal prosthetic weight.Design: Nonrandomized study.Setting: 5 transtibial amputees. The inclusion criteria aretraumatic unilateral amputee, without cardiopulmonary dis-ease and who can walk without assistance.Interventions: Patients were given light-weight patellartendon bearing (PTB) prosthesis and weights of 0.3, 0.5 kgadded to the center of gravity of the prosthesis and gaitanalysis done.Main Outcome Measures: Measuring gait efficiency bythe Physiological Cost Index (PCI) and gait parameters byCDG Gait analyzer.

S157PM&R Vol. 2, Iss. 9S, 2010