preoperative assessment

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


Preoperative assessment

• Just like the rest of medicine…• History• Physical• Laboratory


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.


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


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


Causes of 3-day postop mortality

System implicated % of cases

Cardiovascular 59 Respiratory 25Renal 22Sepsis 21Hematological 12GI 11Metabolic 10Surgical condition 9CNS 8Hepatic 6

NCEPOD 2002 www.ncepod.org. uk


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


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


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 - -


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


Revised Cardiac Risk Index and Cardiac Events

Risk Factors Cardiac Events (%) 95% CI0 0.4 0.05 – 1.51 0.9 0.3 – 2.1 2 6.6 3.9 – 10.3 3 or more 11.0 5.8 – 18.4



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


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

http://gacguidelines.ca/pdfs/tools/Ontario%20Preoperative%20Testing%20Grid.pdf



OMA-GAC recommendations



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


Withholding preoperative medication

% of patients in whom drug was withheld

Drug Class All surgeries Non-emergencyAnti-anginal 27 22Anti-arrhythmic 25 20Anti-hypertensive 34 33Thyroid 43 31Bronchodilator 16 15Steroids 19 17

NCEPOD 2002 www.ncepod.org. uk


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


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


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


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


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)


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


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??


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?


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)



Risk of cardiac morbidity?



AHA ACC guidelines for cardiac evaluation prior to noncardiac surgery


What about ß-blockers?

Mangano PoldermansTreated 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.


An aspirin an day…

Neilipovitz DA. A&A 2001;93:573-80

Outcome ASA % No ASA %MI 2.71 4.61CVAt 1.12 1.69CVAh 0.59 0.37GI bleed 0.76 0.35Wound bleed 7.71 5.58All adverse events 12.89 12.90Mortality 2.05 2.78QALY 14.79 14.72


ASA and perioperative hemorrhage

Antiplatelet Trialists’ Collaboration. III. BMJ 1994;308:235-48Pulmonary Embolism Prevention Trial. Lancet 2000;355:1295-302

ATC III PEPBleed Control Treated Control Treated

Fatal 0 0.05 0.2 0.2Major 0.4 0.7 2.4 2.9Wound 5.6 7.8 3.9 4.4


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?


Coumadin and thrombosis

Indication Annual RiskTreated

Annual RiskUntreated

Risk Reduction

Atrial fibrillation 2.3 % 7.4% 67%Aortic valve 1.9% 12.3% 85%Mitral valve 4.7% 22.2% 79%


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


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


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


Case 3

• 45 yr old female for lumbar spinal fusion• Uses “some percocets” for pain control• Smokes 1.5 packs per day


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 surgerySorensen 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


Smoking cessation works

Cessation Controln 56 52Age 66 64Pack years 35 37Wound 3 (5%) 16 (31%)Reoperation 2 (4%) 8 (15%)Any complication 10 (18%) 27 (52%)

Moller AM. Lancet 2002;359:114-7


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


Regional anesthesia and outcome

Rodgers A.BMJ 2000;321:1–12

preoperative assessment

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