G. L. Bryson, MD, FRCPC, MScDepartment of AnesthesiologyThe Ottawa Hospital – Civic
Campus
Preoperative Assessment
Risk assessment and management
Department of AnesthesiologyCivic Campus
Objectives
• Perioperative morbidity and mortality• You can’t avoid what you can’t anticipate
• Preoperative testing• Less than you’d expect
• NPO guidelines• Problems
Department of AnesthesiologyCivic Campus
Preoperative assessment
• Just like the rest of medicine…• History• Physical• Laboratory
Department of AnesthesiologyCivic Campus
An approach to preoperative evaluation
• What’s wrong with the patient?• Is the patient is good as they can get?• If not, does it have to be better pre-op?• Getting to the OR is less than half the job.• Anticipate postoperative problems, then plan.
Department of AnesthesiologyCivic Campus
Anesthesia is bad for you• Unable to protect airway
• Aspiration• Obstruction
• Altered control of ventilation• Diminished response to CO2 and O2
• Altered respiratory mechanics FRC, restrictive chest wall defect
• Myocardial depression• Decreased conductivity • Vasodilatation• Immune suppression
Department of AnesthesiologyCivic Campus
The Killing Fields
• Getting patients out of the OR is easy• Getting patients home is another matter• Postoperative course complicated by:
• Increased O2 demand• Myocardial ischemia/infarction• Respiratory depression / VQ mismatching• Hemorrhage • Fluid and electrolyte shifts • Hypercoagulable• Protein catabolism
Department of AnesthesiologyCivic Campus
Causes of 3-day postop mortality
System implicated % of cases
Cardiovascular 59
Respiratory 25
Renal 22
Sepsis 21
Hematological 12
GI 11
Metabolic 10
Surgical condition 9
CNS 8
Hepatic 6
NCEPOD 2002 www.ncepod.org. uk
Department of AnesthesiologyCivic Campus
Functional capacity predicts outcome
• Postoperative cardiac deaths confined to those with VO2Max < 3 METS
Older P. Chest 1999;116:355-62
• Inability to climb 2 flights of stairs 82% PPV (97% specific) for postoperative CV/RS complications
Girish M. Chest 2001;120:1147-51 • Self-reported exercise tolerance < 2 flights of
stairs doubled risk of complications following non-cardiac surgery (20% v 10%)
Reilly DF. Arch Intern Med 1999;159(18):2185-92
Department of AnesthesiologyCivic Campus
ASA Physical Status Classification
Class Description I Healthy II Systemic disease no functional limitation III Systemic disease with functional limitation IV Systemic disease with functional limitation
constant threat to life V Moribund unlikely to survive 24 hrs
with or without surgery E Emergency procedure
Department of AnesthesiologyCivic Campus
ASA class and mortality
ASA Class
Vercanti 1970
Marx 1973
Cohen 1986
Forrest 1990
I 0.07 0.06 0.07 0.00
II 0.24 0.40 0.20 0.04
III 1.43 4.3 1.15 0.59
IV 7.46 23.4 7.66 7.95
V 9.38 50.7 - -
Department of AnesthesiologyCivic Campus
Revised Cardiac Risk Index
Risk Factor Cardiac EventsCrude Data
Adjusted OR(95% CI)
High risk surgery 18/490 (4%)
2.6 (1.3 – 5.3)
CAD 26/478 (5%) 3.8 (1.7 – 8.2)
CHF 19/255 (7%) 4.3 (2.1 – 8.8)
CVD 10/140 (7%) 3.0 (1.3 – 6.8)
Insulin therapy 3/59 (5%) 1.0 (0.3 – 3.8)
Cr > 177 3/55 (5%) 0.9 (0.2 – 3.3)
Lee TH. Circulation 1999;100:1043-1049
Department of AnesthesiologyCivic Campus
Revised Cardiac Risk Index and Cardiac Events
Risk Factors Cardiac Events (%) 95% CI
0 0.4 0.05 – 1.5
1 0.9 0.3 – 2.1
2 6.6 3.9 – 10.3
3 or more 11.0 5.8 – 18.4
Lee TH. Circulation 1999;100:1043-1049
Department of AnesthesiologyCivic Campus
Risk Factor PointsType of Surgery
AAA 15
Thoracic 14
Upper Abdominal 10
Neck 8
Neurosurgery 8
Age
> 80 years 17
70 – 79 years 13
60 – 69 years 9
Functional Capacity
Totally dependent 10
Partially dependent 6
Weight Loss > 10% in past 6 mo
7
COPD 5
11 others worth 4
Points Pneumonia (%)
0 – 15 0.24
16 – 25 1.18
26 – 40 4.6
41 – 55 10.8
> 55 15.8
Arozullah AM. Ann Intern Med 2001;135:847-57.
Incidence 1.5%
30-day mortality 21%
Risk factors for postoperative pneumonia
Department of AnesthesiologyCivic Campus
Preoperative testing
• Routine preoperative testing isn’t helpfulMunro J. Health Technology Assessment 1997;1(12)
• Testing should “follow” history and physical• Like most testing, it’s most helpful when you don’t
know what the answer is.• OMA-GAC statement• http://gacguidelines.ca/pdfs/tools/Ontario%20Preoperative%20Testing
%20Grid.pdf
• Elective versus emergency patient
Department of AnesthesiologyCivic Campus
OMA-GAC recommendations
http://gacguidelines.ca/pdfs/tools/Ontario%20Preoperative%20Testing%20Grid.pdf
Department of AnesthesiologyCivic Campus
TOH fasting guidelines
• For elective surgery:• NPO solids at 2400• Unlimited water until 3 hours preop
• For urgent surgery:• NPO solids a minimum of 6 hours• NPO clear fluids 3 hours• Modified by urgency of surgery
• All usual medications given, except• Anticoagulants, oral hypoglycemics, MAOIs• Insulin and glucose require physician order
Department of AnesthesiologyCivic Campus
Withholding preoperative medication
% of patients in whom drug was withheld
Drug Class All surgeries Non-emergency
Anti-anginal 27 22
Anti-arrhythmic 25 20
Anti-hypertensive 34 33
Thyroid 43 31
Bronchodilator 16 15
Steroids 19 17
NCEPOD 2002 www.ncepod.org. uk
Department of AnesthesiologyCivic Campus
Valvular or congenital heart disease
• Stenotic lesions intolerant of changes in preload/afterload
• RL shunts aggravated by hypoxia & SVR • Important to understand the plumbing
• Preoperative echocardiogram helpful • Anticoagulation issues• SBE prophylaxis
• www.americanheart.org/Scientific/statements/1997/079701.html
Department of AnesthesiologyCivic Campus
Subacute bacterial endocarditits
• Oral / dental surgery• Ampicillin 2000 mg (50 mg/kg) IV 60 min pre-op• Cefazolin 1000 mg (25 mg/kg) IV 60 min pre-op• Clindamycin 600 mg (20 mg/kg) IV 60 min pre-op
• Gastrointestinal, genitourinary• As above, plus• Gentamicin 1.5 mg/kg IV 60 minutes pre-op • Vancomycin 1000 mg (20 mg/kg) IV 60 minutes
pre-op, if penicillin-sensitive• Repeat Ampicillin 6 hours post-op if high-risk
pathologyhttp://circ.ahajournals.org/cgi/content/full/96/1/358
Department of AnesthesiologyCivic Campus
Pacemakers and AICDs
• Pacemakers• Should be evaluated preoperatively• If pacemaker dependent, reprogram to VOO• Rate adaptive functions may need to be disabled• Use bipolar cautery, if possible• Short bursts if monopolar required
• AICDs• Must be turned off preoperatively• in monitored environment
Department of AnesthesiologyCivic Campus
Anticoagulation• Normal coagulation expected preoperatively• Neuraxial hematoma & surgical hemorrhage
• Coumadin held for 5 days• INR less than 1.4• LMWH held for 24 hours • UFH held for 6 hours• Fancy antiplatelet drugs withdrawn (7 days)• ASA is OK for most procedures
• Vitamin K needs a day• Don’t drown folks with FFP
Department of AnesthesiologyCivic Campus
I think that’s a blood thinner• Clopidogrel (Plavix) • Abciximab (RheoPro) • Eptifibatide (Integrilin) • Low molecular weight heparins
• Dalteparin (Fragmin)• Enoxaparin (Lovenox)• Nadroparin (Fraxiparin)• Tinzaparin (Innohep)
• Fondaparinux (Arixtra)• Ximelagatran (Exanta)
Department of AnesthesiologyCivic Campus
Summary
• Preoperative assessment must identify and anticipate perioperative problems
• Getting to the OR is the easy part• Communication is essential• Fasting should not exclude hydration or
medication• Laboratory testing should be individualized
Department of AnesthesiologyCivic Campus
The surgeon is a carnivorous beast. It’s happy only when there is fresh meat on the table. Ross Kerridge MD, FRCA
Newcastle, AustraliaAt WCA Montreal 2000
Questions??
Department of AnesthesiologyCivic Campus
Case 1
• 64 yr old male scheduled for hemicolectomy for colon ca. Past history includes:• Diabetes x 15 years (on insulin)• CVA 3 years ago• Stable CCS 3 angina• He takes diltiazem, hctz, and plavix
• What is his risk of cardiovascular event?• What preoperative tests would you order?• What preop instructions would you give?
Department of AnesthesiologyCivic Campus
Revised Cardiac Risk Index
Risk Factor Cardiac EventsCrude Data
Adjusted OR(95% CI)
High risk surgery 18/490 (4%)
2.6 (1.3 – 5.3)
CAD 26/478 (5%) 3.8 (1.7 – 8.2)
CHF 19/255 (7%) 4.3 (2.1 – 8.8)
CVD 10/140 (7%) 3.0 (1.3 – 6.8)
Insulin therapy 3/59 (5%) 1.0 (0.3 – 3.8)
Cr > 177 3/55 (5%) 0.9 (0.2 – 3.3)
Lee TH. Circulation 1999;100:1043-1049
Department of AnesthesiologyCivic Campus
Risk of cardiac morbidity?
Lee TH. Circulation 1999;100:1043-9
Department of AnesthesiologyCivic Campus
AHA ACC guidelines for cardiac evaluation prior to noncardiac surgery
Department of AnesthesiologyCivic Campus
What about ß-blockers?
Mangano Poldermans
Treated Control Treated Control
Patients 99 101 59 53
In-hospital mortality 1(1) 2 (2) 2 (3) 9 (17)
In-hospital death/mi 2 (2) 4 (4) 2 (3) 18 (34)
Post-discharge PCM* 16 (17) 32 (32) 8 (14) 14(32)
Mangano DT. NEJM 1996;335(23):1713-20Wallace A. Anesthesiology 1998;88(1):7-17
Poldermans D. NEJM 1999;341(24):1789-94Poldermans D. Eur Heart J 2001;22(15):1353-8.
Department of AnesthesiologyCivic Campus
An aspirin an day…
Neilipovitz DA. A&A 2001;93:573-80
Outcome ASA % No ASA %
MI 2.71 4.61
CVAt 1.12 1.69
CVAh 0.59 0.37
GI bleed 0.76 0.35
Wound bleed 7.71 5.58
All adverse events 12.89 12.90
Mortality 2.05 2.78
QALY 14.79 14.72
Department of AnesthesiologyCivic Campus
ASA and perioperative hemorrhage
Antiplatelet Trialists’ Collaboration. III. BMJ 1994;308:235-48Pulmonary Embolism Prevention Trial. Lancet 2000;355:1295-302
ATC III PEP
Bleed Control Treated Control Treated
Fatal 0 0.05 0.2 0.2
Major 0.4 0.7 2.4 2.9
Wound 5.6 7.8 3.9 4.4
Department of AnesthesiologyCivic Campus
Case 2
• A 45 yr old male is scheduled for TURP.• He has hypertension, atrial fibrillation, and
had a mechanical aortic valve placed 4 years ago.
• He takes metoprolol and coumadin.• What investigations?• What instructions?
Department of AnesthesiologyCivic Campus
Coumadin and thrombosis
IndicationAnnual Risk
TreatedAnnual Risk
UntreatedRisk
Reduction
Atrial fibrillation 2.3 % 7.4% 67%
Aortic valve 1.9% 12.3% 85%
Mitral valve 4.7% 22.2% 79%
Department of AnesthesiologyCivic Campus
Who needs special care with coumadin?
• DVT < 3 months ago• History of recurrent DVT• Arterial thromboembolism < 3 months ago• Mechanical prosthetic heart valves• Tissue prosthetic heart valves + embolism• Thrombophilia (lupus ac, Factor V - L, C&S)• Atrial fibrillation + embolism
Department of AnesthesiologyCivic Campus
Coumadin withdrawal plan
• Day -5. Stop coumadin.• Day -3. Dalteparin 200 u·kg-1 sc.• Day -2. Dalteparin 200 u·kg-1 sc.• Day -1. Dalteparin 100 u·kg-1 sc.• Day 0. Check INR pre-op• Day +1. Is surgical blood loss controlled?
Restart coumadinDalteparin 200 u·kg-1 until INR
>2.0
Department of AnesthesiologyCivic Campus
Subacute bacterial endocarditits
• Oral / dental surgery• Ampicillin 2000 mg (50 mg/kg) IV 60 min pre-op• Cefazolin 1000 mg (25 mg/kg) IV 60 min pre-op• Clindamycin 600 mg (20 mg/kg) IV 60 min pre-op
• Gastrointestinal, genitourinary• As above, plus• Gentamicin 1.5 mg/kg IV 60 minutes pre-op • Vancomycin 1000 mg (20 mg/kg) IV 60 minutes
pre-op, if penicillin-sensitive• Repeat Ampicillin 6 hours post-op if high-risk
pathologyhttp://circ.ahajournals.org/cgi/content/full/96/1/358
Department of AnesthesiologyCivic Campus
Case 3
• 45 yr old female for lumbar spinal fusion• Uses “some percocets” for pain control• Smokes 1.5 packs per day
Department of AnesthesiologyCivic Campus
Smoking is bad for you
• 6x increase in pulmonary complications• Need to stop > 4 weeks preop
Bluman LG. Chest 1998 Apr;113(4):883-9
• 3x increase in wound complications following breast surgery
Sorensen LT Eur J Surg Oncol 2002 Dec;28(8):815-20
• 2x increase risk of bony non-unionAndersen T. Spine 2001 Dec 1;26(23):2623-8
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Smoking cessation works
Cessation Control
n 56 52
Age 66 64
Pack years 35 37
Wound 3 (5%) 16 (31%)
Reoperation 2 (4%) 8 (15%)
Any complication 10 (18%) 27 (52%)
Moller AM. Lancet 2002;359:114-7
Department of AnesthesiologyCivic Campus
Narcotic tolerance
• Important to document just how much narcotic patients are taking preoperatively
• Previous intake must be accommodated in perioperative care
• If patient takes 2 percocets 6 x day• 60 mg oxycodone = 90 mg morphine• 90 mg morphine po = 22.5 mg morphine IV• Adjust PCA settings accordingly
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Regional anesthesia and outcome
Rodgers A.BMJ 2000;321:1–12