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Preoperative Medical Evaluation of the Surgical Patient 

A. Introduction

The medical consultant is often asked to evaluate an individual prior to surgery. The general goals of this consultation are to:

• Identify unrecognized co-morbid disease and risk factors for medical complications of surgery.

• Optimize preoperative medical condition.

• Understand, recognize, and treat potential complications.

• Work as a team with surgeon and anesthesiologist.

Risk and benefit of the proposed procedure must be balanced:

• Why was the consult requested?

• What is the benefit to the patient of the proposed procedure?

• May one substitute a lower risk procedure?

• What are the known risks?

• What is the balance of risk-benefit?

• What are the patient's goals?

The internist assesses risk; the £mal analysis rests with the surgeon and the patient. The internist may be seeing the patient for the first time or may be the primary care physician evaluating the patient in the office prior to considering a surgical referral.

B. Principles of Consultation

• Restrict advice to the internist's unique areas of expertise.

• Example: OK to advise on perioperative insulin management. The selection of anesthetic technique is better left to the anesthesiologist.

• Keep number of recommendations to a minimum.

• Adherence to recommendations diminishes for consults with more than 5 recommendations (Am J Med 1983;74:870).

• Clarify the specific reason for the consult request. Content of consult will differ for "routine consult request than for request to evaluate risk of postoperative pulmonary complications in a high risk patient with COPD.

• Adherence to consultant's recommendations is greater for consults requested early in a patient's hospital course (J Fam Pract 1996;42:259-63). This may relate to a greater degree of perceived urgency on the part of the referring physician early on in a patient's hospital stay.

• Follow patients through the postoperative period as many perioperative complications occur during this time.

• Remember: The preoperative patient is not being "cleared." This may incorrectly imply there is no risk. Rather, the consultant may determine that the patient is at average risk for the proposed procedure, which should be the assessment in the chart if no factors are found which increase perioperative risk.

• Goldman's Ten Commandments of Consultation are useful guides for the consultant (Arch Int Med 1983;143:1753):

• Determine the Question.

• Establish Urgency.

• Look for Yourself.

• Be as Brief As Appropriate.

• Be Specific.

• Provide Contingency Plans.

• Honor Thy Turf.

• Teach ... with Tact.

• Talk is Cheap ... and Effective.

• Follow-up.

C. Effects of Anesthesia

• Modem anesthesia is extremely safe.

• Patient and surgical factors are more important risk predictors than anesthetic considerations (JAMA

1988;260:2859).

• ASA (Dripps) Classification is a powerful predictor of overall perioperative mortality. It also predicts cardiac and pulmonary morbidity.

ASA Classification

Class Systemic Disturbance Mortality*
1 Healthy patient with no disease outside of the surgical process <0.03%
2 Mild-to-moderate systemic disease caused by the surgical condition or by other pathologic processes 0.2%
3 Severe disease process which limits activity but is not incapacitating 1.2%
4 Severe incapacitating disease process that is a constant threat to life 8%
5 Moribund patient not expected to survive 24 hours with or without an operation 34%
E Suffix to indicate an emergency surgery for any class Increased

* Cohen et al. JAMA 1988; 260:2859

 

1. Sources of Anesthetic Risk

• Stress response to anesthetic drugs and interventions.

• Adverse drug effects.

• Mechanical and operator error.

2. Organ Effects

• Cardiac

• Inhalational agents are all myocardial depressants.

• Leads to "preload" dependence.

• Therefore, accentuated hypotensive response to induction of anesthesia in patients who are volume depleted, overdiuresed, or have poor ventricular function.

• Autonomic neuropathies, such as diabetic, also accentuate hypotension with anesthetic induction.

• Pulmonary

• Vital capacity decreased by 50%

• Decreased FRC below closing volumes leads to atelectasis and V/Q mismatch

• Decreased mucociliary clearance.

• Loss of sighing breaths.

• Depression of response to hypoxia and hypercarbia.

• Diaphragmatic dysfunction, greatest in thoracic and upper abdominal surgery

3. Spinal (or epidural) versus general anesthesia

• No difference in cardiac mortality.

• Probable decrease in the risk of pulmonary complications.

D. Preoperative Evaluation of Healthy Individuals

Perioperative risk is very low in healthy individuals, estimated at 0.03% or less. Therefore, additional evaluation will by definition have a low yield and a high likelihood of false positive results.

1. History

• The most important factor in evaluation of the healthy patient

• Questionnaire studies have used simple screening instruments to define a low risk population.

• In one questionnaire study, only 9 of 370 patients had surgically significant medical issues and screened incorrectly as low risk (Can J Anaesth 1998;45:87). This questionnaire follows:

1. Have you ever had a heart attack?

2. Have you ever had heart trouble?

3. Have you ever had heart failure?

4. Have you ever had fluid in your lungs?

5. Do you have a heart murmur?

6. Did you have rheumatic fever as a child?

7. Do you ever have chest pain, angina, or chest tightness?

8. Have you ever been treated for an irregular heart beat?

9. Do you have high blood pressure?

10. Do you ever have difficulty with your breathing?

11. Do you have asthma, bronchitis, or emphysema?

12. Do you cough frequently?

13. Does climbing one flight of stairs make you short of breath?

14. Does walling one city block make you short of breath?

15. Do you now or have you recently smoked cigarettes? How many packs? How many years?

16. Do you have liver disease, or a history of jaundice or hepatitis?

17. Do you drink more than three drinks of alcohol per day?

! 8. Do you have indigestion, heartburn, or a hiatus hernia?

19. Do you have a history of thyroid problems?

20. Do you have diabetes?

21. Do you have a kidney problem?

22. Do you have numbness or weakness of your arms or legs?

23. Do you have epilepsy, blackouts, or seizures?

24. Have you had problems with blood clots or excessive bleeding?

25. Do you have any other important medical problems? Please list.

26. Have you ever had an anesthetic? If yes, when was your last one?

27. Have you or a member of your family had a reaction to an anesthetic?

28. Do you have arthritis or pain in your neck or jaw?

29. Do you have dentures, capped or loose teeth?

30. Do you think you may be pregnant?

31. Have you taken prednisone, steroid medication, or cortisone-like drugs in the past year?

32. Please list any food or medication allergies that you have.

33. Please list any medications you are currently taking.

34. Please list any operations you have had in the past.

35. If this is the day of surgery, when did you last eat or drink?

36. Age Height Weight

 

Another study administered the following simple questionnaire. Patients who answered no to all questions were at average risk. There was no additional risk adjustment from history, exam, or labs in these patients (Br Med J 1980:1:509).

1. Do you feel unwell?

2. Have you had any serious illnesses in the past?

3. Do you get more short of breath on exertion than other people of your age?

4. Do you have any cough?

5. Do you have any wheeze?

6. Do you have any chest pain on exertion (angina type)?

7. Do you have any ankle swelling?

8. Have you taken any medicine or pills in the last 3 months? (including excess alcohol)?

9. Have you any allergies?

10.Have you had an anesthetic in the last 2 months?

11.Have you or your relatives had any problem with a previous anesthetic?

12.Observation of serious abnormality from "end of bed" (which might affect anesthetic)?

13.Date of last menstrual period?

• Exercise capacity

• Exercise capacity is an important determinant of perioperative risk

• Clinicians should ask all patients about exercise capacity prior to surgery

• Good exercise capacity generally predicts a low cardiac and pulmonary risk of surgery (Circulation 1996;93:1278)

• Medication use

• Include OTC meds such as ASA, NSAID's, etc.

• Age

• Age is variably reported as a risk factor for perioperative risk.

• However, it is difficult to establish the risk of age itself from the risk of comorbidities common in older patients.

• When adjusted for ASA class, the perioperative risk is the same across all age groups (Anesthesiology 1973;39:54-8).

2. Laboratory Testing

• Routine screening labs add little to the low overall risk assessment in healthy patients.

• Given the low prevalence of disease in patients who report they are healthy and have a negative questionnaire,

most positive test results are false positives.

• The more "screening" lab tests are ordered, the more likely one will find a false positive abnormal result in a healthy patient.

 

Predictive Value and Prevalence for a Test with 95% Sensitivity and Specificity

Prevalence of Disease (%) Predictive Value of Positive Test (%)
0.1 1.9
1 16.1
2 27.9
5 50.0
50 95.0

Probability of Obtaining an Abnormal Result in a Screening Battery

(Normal result defined as <2 S.D. from the mean)

 
Number of Independent Tests Probability of Abnormal Test (%)
1 5
2 10
4 19
6 26
10 40
20 64
50 92
90 99
 

Support from the medical literature for restraint in test ordering.

• 2000 sequential patients in UCSF study (JAMA 1985;253:3576)

• 60% of routinely ordered tests not clinically indicated

• 0.22% surgically significant abnormal results

• No instance where abnormal result recognized and acted on

 
Test #Tests #Abnormal

results

#Unindicated

abnormal

results

#Unindicated surgically significant abnormal results
Prothrombin Time 650 2 0 0
PTT 650 1 0 0
Platelet Count 1320 3 2 1
CBC 4660 22 2 0
Differential Count 1480 2 1 0
SMA-6 3200 41 1 0
Glucose 3100 25 4 2


• Similar outcome in Mayo Clinic study (Mayo Clinic Proc 1991; 66:155)

• 3782 patients.

• 160 abnormal results noted in routine preoperative testing

• 47 of which prompted further assessment

• 10 of which required treatment

• Only one requiring pharmacologic treatment.

• Retrospective review of 1044 patients who underwent surgery with no preoperative testing (Mayo Clin Proc 1997;72:505).

• Median age 21 years.

• 97% ASA class I or II.

• No deaths or major perioperative morbidities.

• Value of recent tests

• Study of 7549 preop tests in 1109 patients (Ann Int Med 1990; 113:969-73).

• Of 3096 previous normal results, only 13 tests repeated at time of surgery were abnormal, most were predicted based on clinical history

• Authors concluded safe to use laboratory test results obtained within past 4 months as preoperative tests if normal

• Specific tests

• Complete blood count- Anemia is present in 1% of asymptomatic patients. Blood loss common during major surgery. Baseline may be helpful prior to such procedures.

• Electrolytes- Incidence of unexpected abnormalities very low (<1%). Not routinely recommended.

• Renal function- Renal insufficiency increases with age. Its presence may require med dose adjustments. Suggest for patients over age 50 years, and if hypotension or nephrotoxic meds likely

• Glucose- No definite relationship between asymptomatic hyperglycemia and perioperative morbidity, not routinely recommended.

• Liver function tests- Asymptomatic mild liver test abnormalities are not known to be associated with perioperative morbidity. Clinical liver disease may pose a risk, these patients would be identified without screening. Not routinely recommended.

• Tests of hemostasis- Incidence of surgically significant abnormalities in patients without a clinical history of bleeding tendency is extremely low. Reserve these tests for patients with a known bleeding diathesis or an illness associated with bleeding tendency.

• Urinalysis-No evidence that asymptomatic pyuria increases risk of surgical site infections. Renal dysfunction is better detected by serum creatinine. Not recommended.

• EKG- Goal is the detection of prior silent MI or unsuspected arrhythmia that would increase cardiac risk.

• In a study of 1000 ASA class I and II patients, an abnormal EKG was not significantly predictive of the risk of perioperative cardiac events (J Cardioth Vase Anesth 1997; 11:752-5).

• Recommend the indications of Goldberger and O'Konski (Ann Int Med 1986; 105:552-7):

• Men over 40 y.o.

• Women over 55 y.o.

• Clinical evaluation suggests heart disease

• At risk for electrolyte abnormalities

• Systemic disease associated with possible unrecognized heart disease

• Chest X-ray- Incidence of surgically important abnormalities is very low in patients with no risk factors for cardiac or pulmonary disease, and was 0.3% in one study (JAMA 1983;250:3209). Not routinely recommended, should obtain in higher risk patients based on age or clinical disease.

•Beth Israel Deaconess Medical Center guidelines

• CBC

• Type and screen

• CXR for patients over age 60 (if not obtained within past 6 months)

• EKG for male pts over 45 yo, female pts over 55 yo (if not obtained within past month).

• All other tests at discretion of ordering physician.

3. Recommendations:

• Screening questionnaire for all patients

• History of exercise tolerance for all patients

• Blood pressure and pulse for all patients

• History and physical examination if one of the above is abnormal, in patients over 60 years, or in those undergoing major surgery

• Pregnancy test for women who may be pregnant

• Hematocrit for surgery with expected major blood loss

• Serum creatinine concentration if hypotension is expected, nephrotoxic drugs will be used, or the patient is above age 50

• ECG recommendations of Goldberger, unless obtained within the previous month

• Chest x-ray for patients over 60 years, or those with suspected cardiac or pulmonary disease, unless performed within the past 6 months

• Normal lab tests obtained within past 4 months need not be repeated if clinically stabl

• All other tests only if the clinical evaluation suggests a likelihood of disease

E. Pulmonary Disease in Surgical Patients

Postoperative pulmonary complications are a major source of morbidity and mortality. They are at least as frequent as clinically important cardiac complications and contribute to prolonged hospital stays and expense.

1. Definition- Definitions vary widely. More recent authors favor definitions that include abnormalities that are clinically significant and adversely affect the clinical course. This includes: • Atelectasis

• Infection, including bronchitis and pneumonia

• Prolonged mechanical ventilation and respiratory failure

• Exacerbation of underlying chronic lung disease

• Bronchospasm

2. Patient-Related Risk Factors

• COPD

• 3- to 5-fold increase in pulmonary complications.

• Decreased breath sounds, prolonged expiration, rales, wheezes, and rhonchi on physical examination predict a 5-fold increase in pulmonary complications in one study (Chest 1996;110:744)

• Smoking

• 2- to 6-fold increase in risk, even among patients without apparent COPD.

• Risk is highest for current smokers and those who have smoked within past one to two months (Mayo Clin Proc 1989;64:609)

• Higher risk for smokers who stop or reduce cigarettes within one month than those who continue to

smoke! (Chest 1998;113:883)

• Should advise smokers to stop smoking for a full eight weeks prior to elective surgery

• General health status

•Goldman cardiac risk index predicts risk

• ASA Class predicts postoperative pulmonary complications in addition to overall mortality

• Poor exercise capacity increases risk

• Obesity

• Data are mixed.

• Studies confounded by difficulty distinguishing obesity from associated comorbid conditions.

• Most studies show no increase in pulmonary complications, even for morbid obesity.

• Age

• Not a risk factor for pulmonary complications once comorbid conditions considered and patients correctly classified by ASA class.

• Respiratory infection

• URI not well studied; probably small risk if any.

• Bronchitis or pneumonia are risk factors. One should delay surgery if change in character or amount of sputum.

3. Procedure-Related Risk Factors

•Surgical Site

• This is the strongest overall risk factor for pulmonary complications

• Upper abdominal and thoracic surgery are greatest risk (20-50%)

• Result of splinting, diaphragmatic dysfunction from pain.

• Lower abdominal has a lower risk (0-5%)

• Pulmonary complications rare in other surgeries

• Laparoscopic cholecystectomy is lower risk (<1% in one large study)

• Duration of surgery

• Surgery lasting more than 3 hours increases risk of pulmonary complications

• Neuromuscular blockade

• Pancuronium leads to higher incidence of postoperative residual neuromuscular blockade than shorter-acting vecuronium or atracurium (Acta Anaesthesiol Scand 1997;41:1095-1103).

• Among patients with residual block, 4-fold increase in pulmonary complications with pancuronium.

4. Preoperative Risk Assessment

• History and physical examination are most important.

• Evaluate exercise capacity, exertional dyspnea, cough.

• Assess for presence of above risk factors.

5. Role of Pulmonary Function Tests

• Obtain in all patients prior to lung resection (consensus on this indication)

• Role in non resective surgery is controversial

• Even high-risk patients as defined by PFTs may undergo surgery with an acceptable risk. (Arch Int Med 1992; 152:967).

• 107 operations in 89 patients with severe COPD

• All patients with FEV1 <50% predicted and FEV1/FVC <70%.

• Conclusion is that even high risk patients, as defined by spirometry, can undergo surgery with acceptable degree of risk, with the possible exception of patients undergoing CABG



Operation N Minor pulmonary complication Major pulmonary

complication

Death
CABG 8 1 0 5
Other thoracic 7 0 1 0
Upper abdominal 8 2 2 0
Lower abdominal 8 7 0 0
Orthopedic 8 3 0 0
Regional anesthesia 19 2 1 0
Head and neck 11 1 1 1
Urologic 18 1 1 0



• Clinical features more predictive than PFTs in assessing risk of pulmonary complications (Chest 1996;110:744)

• Nested case control study of 164 patients undergoing abdominal surgery

• Primary outcome measure was postoperative pulmonary complications

• Clinical features predicted risk of postoperative pulmonary complications, while abnormal spirometry was not predictive in this study



Variable Odds ratio P value
Abnormal chest physical examination 5.8 0.045
Abnormal chest radiograph 3.2 0.038
Goldman cardiac risk index, per point 2.04 0.01
Charlson comorbidity index, per point 1.6 0.048
Abnormal FEV1 1.0 Not significant

 

• Studies suggesting benefit of PFTs have been flawed (Arch Int Med 1989; 149:280).

• May be most useful in evaluating patients with exercise intolerance or dyspnea that remains unexplained after clinical evaluation.

• The American College of Physicians position statement on preoperative PFTs remains the standard; though guidelines may be more liberal than supported by current data (Ann Int Med 1990;112:793-4):

• Coronary bypass or upper abdominal surgery with a history of tobacco use or dyspnea

• Lower abdominal surgery if uncharacterized pulmonary disease with anticipated prolonged or extensive surgery

• Head and neck or orthopedic surgery with uncharacterized pulmonary disease

• All patients undergoing lung resection

6. Risk reduction strategies

• Preoperative

• Cigarette cessation for at least 8 weeks

• Optimize COPD or asthma. Bronchodilators for symptomatic patients. Theophylline only if used chronically. Liberal use of steroids to achieve best baseline appropriate and safe in preoperative setting. Goal peak flow 80% of personal best or predicted for asthmatics.

• Antibiotics only if change in character of sputum to suggest infection, not warranted routinely.

• Begin patient education on lung expansion maneuvers.

• Intraoperative

• Epidural or spinal anesthesia if possible in high risk patients.

• Regional nerve block even lower risk

• Avoid pancuronium in high risk patients

• Select shorter duration procedures (less than 3 hours) in high risk patients.

• Consider less ambitious lower risk procedures in high risk patients when possible

• Postoperative

• Lung expansion maneuvers

• Deep breathing exercises (chest PT) or incentive spirometry preferred

• Each reduces risk of pulmonary complications by one half

• CPAP equally effective though more expensive and labor intensive. Reserve for patients unable to cooperate with deep breathing or incentive spirometry.

• Pain control

• Postoperative epidural analgesia reduces the risk of pulmonary complications in high risk upper abdominal, thoracic, and aortic surgery.

• Postoperative intercostal nerve blocks reduce incidence of postoperative pulmonary complications in high-risk patients.

F. The Surgical Patient with Potential Adrenal Insufficiency

1. Primary adrenal insufficiency (Addison's)



Time Management
Day before surgery Double Hydrocortisone (HC) dose
Midnight 100 mg HC IM (skip for same-day surgery)
Six a.m. 100 mg HC IM
O.R. 100 mg HC infused
First 24 hrs. 100 mg HC IV/IM q 6-8 hours
Post-op Taper by 50% daily, change to usual PO dose as tolerated. No need for additional mineralocorticoid


2. Steroid Suppression

• Obtain the history!

• Pituitary-adrenal axis suppression potentially present:

• Any patient on chronic steroids.

• 1 week of suppressive doses (i.e. prednisone >7.5 mg qd) within past 12 months.

• ACTH stimulation test can conf'mn integrity of pituitary-adrenal axis, but usually unnecessary.

• Standard management

• Give stress dose steroids, ie, 300 mg/24 hours hydrocortisone or equivalent.

• In patients not presently on steroids, protocol for Addison's may be used, taper off in 72 hours.

• Recent study challenges need for stress dose steroids (Surgery 1997; 121:123-9)

• 18 patients receiving chronic prednisone at least 7.5 mg qd.

• Randomized to stress dose steroids, HC 100 IV mg preop, then 25 mg q 6hrs for two days, then q 12 hrs for one day; or placebo saline.

• One episode hypotension in each group, responded to saline. No other complications in placebo group.

• If validated in larger trials, may change standard approach to perioperative steroid coverage.

G. The Diabetic Surgical Patient

1. Surgical Risks

• Altered wound healing; poor collagen formation.

• Susceptibility to infection

• Wound infection 11% in diabetics vs. 2% in controls in hip replacement surgery (Acta Diabetol 1984; 21:275)

• Micro/Macro vascular disease - may be occult.

• Autonomic neuropathy

• Perioperative bp lability (Anesthesiology 1989;70:591-7)

• A recent study challenges this premise. Though diabetics had a higher incidence of autonomic dysfunction than non diabetics, there was no increase in the incidence of hypotension in response to anesthetic induction (Anesth Analg 2001;88:985).

• Increased risk for perioperative cardiac arrest

• Increased risk of aspiration due to gastroparesis.

• Hyperglycemia

• Effect of stress response hormones

• One in four diabetics first present in perioperative period.

• Hypoglycemia - may be masked by anesthesia.

• Risk of ketoacidosis, hyperosmolar nonketotic coma.

• Lipolysis favored due to stress response hormones.

• Increased incidence of renal disease.

2. Preoperative Evaluation

• Focus on end organ complications.

• Particularly careful assessment for possible cardiac disease, functional assessment 

• Cardiac disease is the most common cause of perioperative mortality. 

• Labs

• Routine EKG given potential for silent MI. 

• Electrolytes, renal function, glucose 

• Urinalysis (exclude occult UTI).

3. Principles of Glucose Management

• Prevent hypoglycemia, correct acid/base and electrolyte abnormalities.

• Provide sufficient carbohydrate to inhibit lipolysis.

• Monitor frequently; ideal goal 120-180.

• Recommendations:

Diet-controlled

• "No glucose - no insulin".

• IVF contain no glucose.

• Careful perioperative monitoring of BS by f'mgersticks.

Oral Agents

• Discontinue prior to surgery to prevent hypoglycemia while NPO on day of procedure.

• Chlorpropamide D/C 2-3 days before procedure.

• Other agents D/C day before.

• Metformin also D/C day before (risk of lactic acidosis).

• If glucose >240 mg/dL, use regular insulin pro.

• Continuous 5% dextrose at 2ml/kg/hr perioperative.

Insulin-Dependent

• Classic Rx

• Give 50% usual NPH dose in a.m.

• Continuous 5% dextrose at 2ml/kg/hr perioperative.

• Check blood sugar q 2-4 hrs, use additional regular insulin prn.

• Continuous infusion

• 1-2 units regular insulin IV per hour.

• Continuous 5% dextrose.

• Check blood sugar q 1-2 hrs, adjust rate prn.

• Rationale for continuous infusion

• Continuous infusion insulin provides tighter glucose control but at the expense of increased risk of hypoglycemia.

• Experimental and animal data demonstrate impaired collagen formation and granulocyte function in deep wounds with sustained glucose > 250 mg/dl.

• Clinical data to support tighter perioperative control less compelling, though many subspecialty authors favor continuous infusion approach.

• Recent data show a small but significant decrease in the risk of deep sternal wound infections after cardiac surgery among patients treated with continuous infusion insulin. In a prospective study of 2467 cardiac surgical patients, the incidence of sternal infections was 2.0% in the subcutaneous insulin group and 0.8% in the continuous infusion insulin group (Ann Thorac Surg 2001;67:352).

• Recommendation: Use continuous infusion insulin in "brittle" diabetics, cardiac surgery, and major lengthy surgery.

H. Thromboembolism Prophylaxis

Stratify the risk of thromboembolism based on both patient factors and type of surgery.

1. Very High Risk

• Major surgery

• Age >40 yrs plus one of following:

• Previous venous thromboembolism 

• Hypercoagulable state 

• Malignant disease

• Major lower extremity orthopedic surgery 

• Hip fracture 

• Stroke

• Multiple trauma

• Spinal cord injury

2. High Risk

• Major surgery

• Age >60 yrs.

• No clinical risk factors*

Or

• Major surgery

• Age 40-60 yrs

• Clinical risk factors*

Or

• Patients with MI

Or

• Medical patients with clinical risk factors*

3. Moderate Risk

• Any surgery for age 40-60 yrs 

• Major surgery for age <40 yrs 

• No clinical risk factors*

Or

• Minor surgery

• Clinical risk factors

4. Low Risk

• Minor surgery

• Age <40 yrs

• No clinical risk factors*

*Clinical Risk Factors

• Obesity

• Immobilization

• Malignancy

• Varicose veins

• Estrogen use

• Paralysis

• Congestive heart failure

• Myocardial infarction

• Stroke

• Indwelling femoral vein catheter

• Inflammatory bowel disease

• Nephrotic syndrome

• Hereditary or acquired hypercoagulable states

• Prior venous thromboembolism

Aspirin is not recommended as prophylaxis for surgical patients as other measures are more efficacious.

A current consensus statement provides the evidence in support of the following general recommendations

(Chest 1998; 114 suppl 531 S-560S):



Type of Surgery Preferred Prophylaxis Alternative Prophylaxis
Low-risk general surgery

<40 y.o

Minor surgery

No prophylaxis
Moderate-risk general surgery

>40 y.o

Major surgery

No additional risk factors

Low-dose unadjusted heparin or

Low molecular weight heparin

or

Intermittent pneumatic compression

or

Elastic stockings

Intermittent pneumatic compression if prone to hematoma or wound infection
High-risk general surgery

>40 y.o

Major surgery

Additional risk factors

Low-dose unadjusted heparin or

Higher dose regimen of low molecular weight heparin

Warfarin to INR 2-3
Highest risk general surgery Multiple additional risk factors Low-dose unadjusted heparin or

Low molecular weight heparin

Plus

Intermittent pneumatic compression

Low-dose unadjusted heparin or

Low molecular weight heparin

Intracranial neurosurgery Intermittent pneumatic compression +/-

Elastic stockings

Hip replacement Warfarin or

Low molecular weight heparin

or

Adjusted dose heparin

Hip fracture Warfarin 

or

Low molecular weight heparin

Knee replacement Low molecular weight heparin or

Warfarin 

or

Intermittent pneumatic compression



Advantages of low molecular weight heparin as compared with standard unfractionated heparin:

• No need for INR monitoring.

• Once daily administration.

• Fewer wound hematomas.

Disadvantages of low molecular weight heparin:

• More costly (10-20 x more expensive at current costs)

I. Endocarditis Prophylaxis

New guidelines have been published by the American Heart Association (JAMA 1997;277:1794). These differ from

previous recommendations by:

• Cardiac conditions are stratified into high, moderate, and negligible risk.

• An algorithm is presented for patients with MVP.

• The dose of amoxicillin is reduced for dental prophylaxis.

• Erythromycin removed from regimens

• Regimens for GI/GU procedures are simplified.

1) High-Risk Category (Prophylaxis recommended)

• Prosthetic valves (metallic and bioprostheses)

• Previous endocarditis

• Complex cyanotic congenital heart disease

• Surgical systemic pulmonary shunts or conduits

2) Moderate-Risk Category (Prophylaxis recommended)

• Most other congenital malformations

• Acquired valvular dysfunction (ie. Rheumatic heart disease)

• Hypertrophic cardiomyopathy

• MVP with regurgitation and/or thickened leaflets

3) Negligible Risk Category (No prophylaxis recommended)

• Isolated secundum ASD

• Surgical repair of ASD, VSD, VDA

• Previous CABG

• MVP without regurgitation

• Physiologic, innocent, or functional murmurs

• Previous Kawasaki or rheumatic fever without valvular dysfunction

• Pacemakers

4) Dental Procedures for which prophylaxis recommended

• Dental extractions

• Periodontal procedures including surgery, scaling, planing, probing

• Dental implant placement

• Endodontic root canal instrumentation

• Subgingival placement of antibiotic fibers or strips

• Initial placement of orthodontic bands

• Intraligamentary local anesthetic injections

• Prophylactic cleaning where bleeding anticipated

5) Other procedure where prophylaxis recommended

• Respiratory

• Tonsillectomy

• Surgical operations of respiratory mucosa

• Rigid bronchoscopy

• Gastrointestinal

• Sclerotherapy of esophageal varices

• Esophageal stricture dilatation

• ERCP with biliary obstruction

• Biliary tract surgery

• Surgical operations involving intestinal mucosa

• GU Tract

• Prostate surgery

• Cystoscopy

• Urethral dilatation

6) Prophylactic regimens for dental, oral, esophageal, and respiratory procedures

• Standard

• Amoxicillin 2.0g 1 hour before procedure (no post procedure dose)

• Unable to take PO meds

• Ampicillin 2.0g IV or IM 30 min before procedure

• Allergic to penicillin

• Clindamycin 600 mg PO 1 hr before procedure, or

• Cephalexin or cefadroxil 2.0 g PO 1 hr before procedure (not if immediate type hypersensitivity reaction to PCN), or

• Azithromycin or Clarithromycin 500 mg 1 hr before procedure

• Allergic to PCN and unable to take PO meds

• Clindamycin 600 mg IV 30 min before procedure, or

• Cefazolin 1.0g IV or IM 30 min before procedure

7) Prophylactic regimens for genitourinary or gastrointestinal procedures

• High-risk patients

• Ampicillin 2.0 g IM or IV plus gentamicin 1.5 mg/kg IV or IM (not to exceed 120 mg) 30 minutes before procedure and ampicillin l g IV/IM or amoxicillin l g PO 6 hours after

• High-risk patients allergic to penicillin

• Vancomycin 1.0 g IV over 1-2 hrs plus gentamicin 1.5 mg/kg IV/IM (not to exceed 120 mg). Complete injection within 30 min of starting procedure.

• Moderate-risk patients

• Amoxicillin 2.0g PO 1 hr before procedure, or ampicillin 2.0 g IV or IM 30 min before procedure

• Moderate-risk patients allergic to penicillin

• Vancomycin 1.0 g 1V over 1-2 hrs, complete infusion within 30 min of starting procedure.

8) Approach to determining need for prophylaxis in MVP

• Murmur of MR-) prophylaxis

• Click with no murmur or presence of murmur unknown

• If emergency procedure » prophylaxis

• If not emergency, obtain echocardiogram. (controversial opinion)

• MR by echo » prophylaxis

• No MR by echo » no prophylaxis

J. Cardiac Disease

• The most important cause of perioperative morbidity and mortality.

• Requests for preoperative consultation often implicitly are to assess cardiac risk, even if not so stated.

• An assessment of cardiac risk should be part of every preoperative consultation.

• In most cases, a careful history and physical exam are sufficient to assess risk.

1. Risk factors for perioperative cardiac events

• Recent MI

• This is one of two major risk factors.

• Original guideline of 6 months is based on 1972 Mayo Clinic study.

• Increased risk of reinfarction for surgery within 6 months of MI, with the greatest risk in first 3 months.

• After 6 months, the risk leveled off.

• Two subsequent studies showed a similar pattern, but with the absolute risk decreased presumably secondary to improved anesthetic technique, use of hemodynamic monitoring and better risk assessment.

• Note the high mortality of perioperative infarctions.

• There is no difference in risk from previous Q-wave or non Q-wave infarctions.

 

Reinfarction Rates in Surgical Patients with Prior Myocardial Infarction
1972 1978 1983
# Patients 32,877 73,321 733
# Prior MI 422 587 733
0-3 months post MI 37% 27% 6%
3-6 months post MI 16% 11% 2%
>6 months post MI 4-5% 4-5% 1-2%
Infarction without prior MI 0.13%
Mortality of Reinfarction 69% 36%

References - Tarhan S, et al JAMA 1972;220:1451

Steen PA, et al JAMA 1978;239:2566

Rao T, et al Anesthesiol 1983,'59.'499


Congestive Heart Failure

• Congestive heart failure at the time of surgery, or previously, represents the other major risk factor.

• Treatment should be sufficient to control CHF, but not so aggressive as to lead to orthostatic hypotension

• In the studies of Goldman, jugular venous distension and S3 correlated best with adverse outcomes.

• In contrast to MI, perioperative CHF occurs usually within the first hour after procedure.

Correlation between Signs and Symptoms of Preoperative CHF and Risk of Perioperative Pulmonary Edema

(Ann Int Med 1983:98:504)

Sign or Symptom Total Patients (N) % Developing Pulmonary Edema
No H/O CHF 853 2%
Left heart failure by exam or CXR 66 16%
H/O pulmonary edema 22 23%
S3 gallop * 17 35%
Jugular venous distension * 23 30%

• Age

• Independent risk factor for age >70 y.o., conferring three-fold increased risk.

• Arrhythmias

• Risk factors as markers of poor ventricular function

• Not associated with excess arrhythmic death, but rather MI and heart failure.

• More recent prospective data (JAMA 1992; 268:217) suggest that preoperative VEA may not be a risk factor for perioperative cardiac death or MI.

• Type of Surgery

• Increased risk with intra-abdominal, intra-thoracic, and aortic procedures.

• No difference in risk between general and spinal anesthesia.

• Emergency Surgery - Cardiac complications increased four-fold.

2. The following factors have not been independently associated with increased cardiac risk.

• Mild-to-Moderate Hypertension

• Stable hypertension carries excess risk only for diastolic bp>110 (Anesthesiology 1979;50:285).

• Antihypertensive reeds should be continued through a.m. of surgery.

• Initial concerns regarding beta-blockers and blunting of intra-operative hemodynamic responses have proven unfounded. Early discontinuation of beta-blockers is associated with excess perioperative ischemia.

• Stable Angina

• Not a risk factor, although unstable angina shown to be a risk in the modified index of Detsky (J Gen Int Med 1986;1:21 I).

• Diabetes (with the exception of the Eagle criteria for vascular surgery)

• Smoking

• Elevated cholesterol

3. Cardiac Risk Indices

• Goldman Cardiac Risk Index

• Landmark work by Goldman identified principal risk factors and proposed a point system, which has since been validated prospectively by others. (NEJM 1977;297:845).

 

Goldman Cardiac Risk Index
Variable Point Score
History

Age>70 y.o.

Preoperative MI within 6 months



5

10

Physical Examination

S3 gallop or increased JVP >12

Significant Valvular Aortic Stenosis



11

3

EKG

Rhythm other than sinus, or atrial ectopy PVCs >5/minute at any time



7

7

General Medical Status

PO2<60 or PCO2>50

K+<3.0 or HCO3<20

BUN >50 or Creatinine >3.0

Chronic liver disease or debilitation





3
Operation

Intraperitoneal, intrathoracic, or aortic Emergency



3

4

Total Possible Points 53
Class I

Class II

Class III

Class IV

0-5

6-12

13-25

>25

A modified index by Detsky differs by the addition of unstable angina as a significant risk factor (J Gen Int Med 1986;1:211)

Variable Points
Coronary Artery Disease

MI 6 months

MI >6 months

Angina (Canadian Class)

Class III

Class IV

Unstable angina <6 months



10

5



10

20

10

Alveolar Pulmonary Edema

Within 1 week

Ever



10

5

Valvular Disease

Suspected critical aortic stenosis



20
Arrhythmia

Rhythm other than sinus

PVCs >5 at any time



5

5

Poor General Medical Status 5
Age >70 y.o. 5
Emergency Surgical Procedure 10
Total Points:

Class I

Class II

Class III



0-15

20-30

>30



The predictive ability of the Goldman index was confirmed in the following two prospective series. Patients with less than 5 points had less than 1% cardiac death or major complication.

Class (Points) # Patients Life-Threatening Complications Cardiac Death
Goldman Zeldin Goldman Zeldin Goldman Zeldin
I (0-5) 537 590 <1% <1% <1% <1%
II (6-12) 316 453 5% 2% 2% 1%
III (13-25) 130 74 12% 11% 2% 4%
IV (>25) 18 23 56% 26% 22% 4%

Goldman = Original series by Goldman, NEJM 1977; 297: 845

Zeldin = Subsequent prospective study of Zeldin, Can J Surg 1984; 27:402

 

4. Strategies to minimize risk.

• Recent MI

• Defer truly elective surgery for 6 mos.

• Semi-elective surgery may be considered after 6-12 weeks following a careful cardiac functional assessment.

• CHF

• Optimize condition.

• Avoid over-diuresis and orthostasis.

• PACs, PVCs

• Indications for perioperative antiarrhythmics the same as in non-surgical setting.

• Routine suppression not associated with improved outcomes.

• Aortic Stenosis

• All symptomatic patients should be evaluated.

• Be certain that patient is active enough to provoke symptoms.

• Poor general medical status

• Correct as appropriate.

• Type of operation

• Consider less ambitious procedure if high risk.

5. Use ofPerioperative Atenolol to Decrease Cardiac Risk (NEJM 1996;335:1713).

• Prospective study of 200 patients undergoing non-cardiac surgery.

• Patients with either CAD or two risk factors for CAD.

• Inclusion Criteria

• Known CAD

• Previous MI

• Angina

• Atypical angina with positive ETT

• CAD risk factors (at least two of following)

• >65 yo

• HTN

• Current Smoker

• Cholesterol 240

• Diabetes

• HR >55 and sbp >100 at time of each intervention.

• Exclusion criteria

• No third-degree heart block, CHF, or bronchospasm.

• Intervention

• Atenolol 5mg IV over 5 minutes, given 30 minutes preop and repeated after 5 minutes

• Repeat infusion (5mg x2) immediately post op.

• Atenolol 50-100mg PO qd (or 5 mg IV X2 q 12hrs if NPO) beginning post op day #1 and given until discharge.

• Outcomes (of the 194 who survived to leave the hospital)

• 1 year mortality 3% in atenolol group

• 1 year mortality 14% in placebo group.

• Recommendations (from ACP consensus statement Ann Int Med 1997;127:309)

• Use perioperative atenolol for all patients who meet above inclusion criteria.

6. Maintenance ofPerioperative Normothermia

• A recent provocative study evaluated the benefit of maintenance of intraoperative normothermia with a forced air warming blanket (NEJM 1997;277:1127-34).

• 300 patients with CAD or at high risk for CAD undergoing abdominal, thoracic, or vascular surgery.

• Incidence of postoperative morbid cardiac events:

• 1.4% in normothermic group

• 6.3% in usual care group (mild hypothermia)

• Forced air warming blankets are inexpensive and safe. This strategy should be considered pending validation from other trials.

7. Limitations of Cardiac Risk Index

• Underestimates risk in patients undergoing major vascular procedures as risk index was derived from general surgical patients.

• Fails to include severe or unstable angina, a modification later made by Detsky.

• Low score patients still carry some cardiac risk in some prospective analyses.

8. Features of Perioperative MI

• More often present without chest pain.

• Rather may present with hypotension, arrhythmia, pulmonary edema.

• Peak incidence is on third to fourth post-operative days as fluid is mobilized, patient begins to ambulate, pain reeds are decreased.

• High mortality.

9. Preoperative Patient Evaluation; Non-Vascular Surgery

• History

• When history is reliable, good exercise tolerance predicts a similar good response to the stress of anesthesia and surgery.

• In patients with angina, those with class II symptoms (2 bags of groceries up one flight stairs, or 2 blocks level ground walking) generally tolerate surgery well.

• Review of CASS data demonstrates decreased operative mortality in subsequent noncardiac surgery from 2.4% to 0.9% in those angina patients who received CABG (Ann Thorac Surg 1986;41:42). However, the mortality of the CAGB itself (2.3% in CASS Registry) was not included.

• Exercise Testing

• Should be reserved for unreliable historians.

• Has not been shown to be more predictive than clinical data alone in unselected patients undergoing surgery.

• ETT functions to assess exercise tolerance objectively.

• In a study of patients >65 years old (Ann Int Med 1985;103:832), inability to exercise for two minutes to raise the heart rate to >99 was an independent predictor of risk, whereas exercise RVG data were not.

• Interpretation of exercise testing is highly dependent on the pre-test probability of disease.

• Pharmacologic Stress Testing

• Neither dipyridamole thallium nor dobutamine echocardiography has been shown to be helpful in predicting cardiac events in non-vascular surgery.

• It is recommended (ACP consensus Ann Int Med 1997;127:309) that use of these tests be limited to patients undergoing vascular surgery (an opinion not shared by all consensus statements).

10. American Heart Association Guidelines:

• An AHA/ACC task force has recently proposed an alternate approach to risk stratification based on three factors (Circulation 1996; 93: 1278-1317):

• Functional capacity

• Clinical predictors

• Procedure specific risks

• As an example, a patient with minor clinical predictors who can perform activities requiring 4 METS can proceed to low and intermediate risk surgery at average risk.

• These factors are then incorporated in a complex algorithm from these three elements (see reference).

1) Estimated Energy Requirements for Various Activities

 

1 MET                Can you take care of yourself?.

                            Eat, dress, or use the toilet?

                            Walk indoors around the house?

                            Wall a block or two on level ground?

 

4 METs               Do light work around the house like dusting or washing dishes?

                            Climb a flight of stairs or wall up a hill?

                            Wall on level ground at 4 mph?

                            Run a short distance?

                            Do heavy work around the house like scrubbing floors or lifting heavy furniture?

                            Moderate activities like golf, bowling, dancing, doubles tennis.

 

10 METs             Strenuous sports like swimming, singles tennis, football, skiing



2) Clinical Predictors of Increased Perioperative Cardiovascular Risk



Major

• Unstable coronary syndromes

• Recent myocardial infarction with evidence of ischemic risk by clinical symptoms or noninvasive study

• Unstable or severe angina

• May include "stable" angina in sedentary patients.

• Decompensated congestive heart failure

• Significant arrhythmias

• High-grade atrioventricular block

• Symptomatic ventricular arrhythmias in the presence of underlying heart disease

• Supraventricular arrhythmias with uncontrolled ventricular rate

• Severe valvular disease

Intermediate

• Mild angina pectoris (Class I or II)

• Prior myocardial infarction by history or Q waves

• Compensated or prior congestive heart failure

• Diabetes mellitus

Minor

• Advanced age

• Abnormal ECG (LVH, LBBB, ST-T abnormalities)

• Rhythm other than sinus

• Low functional capacity (eg, inability to climb one flight of stairs with a bag of groceries)

• History of stroke

• Uncontrolled systemic hypertension

3) Cardiac Risk Stratification for Noncardiac Surgical Procedures

High (Cardiac Risk Often >5%)

• Emergent major operations

• Aortic and other major vascular

• Peripheral vascular

• Anticipated prolonged surgical procedures

• Anticipated large fluid shifts and/or blood loss

Intermediate (Cardiac risk generally <5%)

• Carotid endarterectomy

• Head and neck

• Prostate

• Intraperitoneal and intrathoracic

• Orthopedic

Low (Cardiac Risk Generally <1%)

• Endoscopic procedures

• Superficial procedure

• Cataract

• Breast

 

The AHA/ACC algorithm has been independently validated by a prospective study of 203 patients undergoing high-risk vascular surgery (Circulation 1997;95:2473).

• 203 patients undergoing aortic surgery

• Following the algorithm, 41 patients underwent non-invasive cardiac testing, 7 underwent coronary angiography, and 1 patient had myocardial revascularization.

• Overall hospital mortality was 3.5%, cardiac mortality and morbidity were 1% and 12.4% respectively.

11. American College of Physicians Guidelines (Ann Int Med 1997;127:309)

• Principles of ACP guidelines:

• Modified (Detsky) clinical index for all patients

• Apply "Eagle" low risk variables criteria to low risk "Detsky" patients.

• Risk stratify intermediate risk "Eagle" patients undergoing vascular surgery.

• Optimize condition of high-risk patients.

• Reserve revascularization for those patients who meet criteria independent of their need for non cardiac surgery.

• Algorithm follows:

12. Preoperative Evaluation; Vascular Surgery

• Clinical Indices

• The Goldman clinical index was derived from general surgical patients.

• Vascular surgery patients are known to have a higher incidence of CAD.

• A series of 1000 consecutive vascular surgery patients showed 13% with 3 vessel or left main disease,and only 8% had normal coronaries.

• Claudication may prevent these patients from exercising sufficiently to display cardiac symptoms.

• Clinical indices do not adequately identify patients at risk for cardiac complications.

• Of 13 cardiac complications in 125 vascular surgery patients, no clinical criteria in one study identified high-risk patients (J Vasc Surg 1991; 14:160). Although a high cardiac risk index was useful, many events occur in patients with low indices.

• Further testing of these patients is necessary

• Exercise Testing

• Most patients are unable to exercise sufficiently to obtain a diagnostic test, i.e. 85% of predicted heart rate.

• A negative test at target heart rate predicts low risk, however less than 30% of such patients achieve the target.

• This test has limited value as a screening test.

• Resting echocardiography

• Although several studies report higher risk with LVEF < 35%, LV dysfunction is not a consistent indicator of perioperative events.

• This test is not recommended as a screening test for risk stratification.

• Dipyridamole-Thallium Testing

• Shown to be superior to exercise testing in vascular surgery patients (J Vasc Surg 1989; 10:51).

Test Sensitivity Specificity Positive Predictive Value
Exercise testing 0.23 0.89 0.56
Dipyridamole Thallium 0.86 0.68 0.61
Both positive 0.18 0.97 0.80

• Administration of dipyridamole causes coronary vasodilation and a "steal" phenomenon past fixed stenoses.

• A negative test has a low predictive value.

• A positive test is associated only with a 10-20% risk of cardiac events.

• One study (NEJM 1994: 330:663) showed no predictive value and found age and definite CAD to be only predictors of risk. This may reflect its use in unselected patients.

• Prior probabilities may be used to define a group most likely to benefit from this test.

• Those at intermediate risk benefit most from dipyridamole thallium testing.

• One study defined clinical variables as (Ann Int Med 1989:110:863):

• Q waves on EKG,

• Age >70,

• Angina,

• Ventricular ectopy requiting treatment

• Diabetes requiring treatment.

• The test was of most value in patients with 1 or 2 clinical variables, or "Eagle" criteria. Events include unstable angina, MI, pulmonary edema, cardiac death.

• Perioperative Ischemia Monitoring

• Preoperative ST segment Holter monitoring has been studied.

• Cannot be used in some patients with resting baseline EKG abnormalities.

• Results are either positive or negative with no gradations to further stratify risk.

• A study of unselected sequential patients showed no benefit from this test (NEJM 1990; 323:1781).

• Inferior to pharmacologic stress tests.

• Should not be used as the sole preoperative test to select patients for angiography.

• Dobutamine Stress Echocardiography

• Dobutamine is infused in incremental doses.

• A positive test is new or worsened motion abnormalities.

• Positive predictive value of from 10-25%

• Negative predictive value of 93-100%.

• A negative test result indicates a low risk with a good deal of certainty.

• This test is of equal value to dipyridamole thallium testing.

• Selection of particular test depends on availability and reliability of test at a given institution.

• Several small studies have challenged the role of preoperative cardiac evaluation prior to major vascular surgery.

• An uncontrolled study of 113 patients undergoing AAA repair found only 2 adverse cardiac events in the entire group and no difference between patients who had preoperative cardiac studies and those who had not (J Vasc Surg 1997;25:152-6). Patients who were denied surgery based on preoperative evaluation were of course excluded.

• Another study found no benefit of preoperative optimization by invasive hemodynamic monitoring in 72 patients undergoing perpipheral vascular surgery (Surgery 1997; 122:584-92).

• A study of 189 patients undergoing AAA repair stratified patients into three groups (Arch Surg 1998; 133:833). The stratification was similar but not identical to the Eagle criteria approach.

• Group I: no cardiac history. Proceed directly to surgery

• Group II: history of stable angina or CAD risk factors. Noninvasive testing

• Group III: unstable angina or previous MI with LV dysfunction. Proceed to cath.

• Using this strategy, there were only two perioperative deaths and two non-fatal MIs.

• 37% of patients underwent revascularization using this algorithm.

• This study also supports the selective use of cardiac evaluation prior to vascular surgery.

13. Selection of High-Risk Patients for Angiography.

• Even high risk patients by non-invasive testing have only a 10-20% rate of cardiac events.

• No controlled studies have examined the benefit of prophylactic CABG or PTCA prior to non cardiac surgery.

• When estimated, the risk of revascularization procedure has approximated the reduced risk of the subsequent noncardiac surgery.

• CASS study of postoperative death and MI in high-risk noncardiac surgery (Circulation 1997;96:1882-7).

• Patients were previously randomized to either CABG or medical therapy of CAD as part of CASS study

• Retrospective review of risk associated subsequent noncardiac surgery

• Reduction of cardiac risk in high-risk noncardiac surgery equaled the risk of CABG itself.

• This study supports conservative medical Rx for patients with CAD and stable sx prior to noncardiac surgery

 

Postoperative death rates among patients undergoing noncardiac surgery based on previous CABG or medical

treatment of CAD (total n=3368)

Type of surgery No CAD (%) CAD Medical Rx (%) CAD Rx CABG (%)
Abdominal 0.7 3.1 1.5
Vascular 0 2.8 1.1
Thoracic 3.2 5.8 2.4
Head and neck 2.2 2.9 3.3
Urologic 0.8 0.9 0.8
Orthopedic 0.7 0.6 0

• Recent consensus suggests that the indications for revascularization are the same as for patients not facing non cardiac surgery. Examples include:

• Unstable angina

• Left main disease

• Three vessel CAD with impaired LV function

• Two vessel CAD with proximal LAD disease and impaired LV function.

• Other high risk-patients should be managed medically.

14. Approach

• One simplified approach to risk stratification follows.

 

Patient Approach to Risk Stratification
Good historian

Class II activities with no angina

Non vascular procedure

History and physical

Modified cardiac risk index

Surgery low risk

Poor historian

Exercise capacity unclear

Exercise testing
Poor historian

Unable to exercise

Dipyridamole thallium testing or dobutamine echocardiography

(Use of these tests in non vascular surgery controversial and unproven to be of benefit)

Vascular surgery

a. High cardiac risk index

b. >3 "Eagle" criteria

c. 1-2 "Eagle" criteria

d. No "Eagle" criteria and low cardiac risk index



High risk

High risk

Dipyridamole thallium testing or dobutamine echocardiography.

Low risk

All high-risk patients Consider coronary angiography if indication for revascularization exists independent of noncardiac surgery.

Prophylactic beta blockers per atenolol protocol

 

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