4. Neurologic System. The patient’s ability to answer health history questions practically ensures a normal mental status (exclude the presence of increased intracranial pressure, cerebrovascular disease, seizure history, pre-existing neuromuscular disease, or nerve injuries).

5. Endocrine System. The patient should be screened for endocrine diseases (diabetes mellitus, adrenal cortical suppression) that may affect the perioperative course.

IV. EVALUATION OF THE PATIENT WITH KNOWN SYSTEMIC DISEASE

A. Cardiovascular Disease

1. The goals are to define risk; determine which patients will benefit from further testing; devise an appropriate anesthetic plan; and identify patients who will benefit from perioperative beta-blockade, intervention therapy, or even surgery (Table 22-5).

2. Independent predictors of complications in the Goldman risk index include high-risk type of surgery, history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, preoperative treatment with insulin, and preoperative serum creatinine >2.0 mg/dL.

3. The presence of unstable angina has been associated with a high perioperative risk of myocardial infarction (MI).

4. The presence of active congestive heart failure before surgery is associated with an increased incidence of perioperative cardiac morbidity.

5. The importance of the intervening time interval between an acute MI and elective surgery (traditionally 6 months or longer) may no longer be valid in the current era of interventional therapy (Table 22-6).

B. Identifying Patients at Risk for Cardiac Disease. For patients without overt symptoms or history, the probability of CAD varies with the type and number of atherosclerotic risk factors present (peripheral arterial disease associated with CAD).

1. Diabetes Mellitus. Autonomic neuropathy is the best predictor of silent CAD.

2. Hypertension. Hypertensive patients with left ventricular hypertrophy and undergoing noncardiac surgery are at a higher perioperative risk than nonhypertensive patients.

a. Although there has been a suggestion in the literature that surgery should be delayed if the diastolic pressure is ≥110 mm Hg, the study often quoted as the basis for this determination demonstrated no major morbidity in that small group of patients.

b. Other authors state that there is little association between blood pressures of <180 mm Hg systolic or 110 mm Hg diastolic and postoperative outcomes. (Such patients are prone to perioperative myocardial ischemia, ventricular dysrhythmias, and lability in blood pressure.)

3. Other Risk Factors. Tobacco use and hypercholesterolemia increase the probability of developing CAD but have not been shown to increase perioperative cardiac risk.

C. Importance of Surgical Procedure (Table 22-7)

1. The surgical procedure influences the scope of preoperative evaluation required by determining the potential range of physiologic flux during the perioperative period.

a. Peripheral procedures performed as ambulatory surgery are associated with an extremely low incidence of morbidity and mortality.

b. High-risk procedures include major vascular, abdominal, thoracic, and orthopedic surgery.

D. Importance of Exercise Tolerance

1. Exercise tolerance is one of the most important determinants of perioperative risk and the need for further testing and invasive monitoring.

2. An excellent exercise tolerance, even in patients with stable angina, suggests that the myocardium can be stressed without failing.

a. If a patient can walk a mile without becoming short of breath, the probability of extensive CAD is small.

b. If patients experience dyspnea associated with chest pain during minimal exertion, the probability of extensive CAD is high, which has been associated with a greater perioperative risk.

3. There is good evidence to suggest that minimal additional testing is necessary if the patient has good exercise tolerance.

V. INDICATIONS FOR FURTHER CARDIAC TESTING. No preoperative cardiovascular testing should be performed if the results will not change the perioperative management.

A. Cardiovascular Tests

1. Electrocardiography

a. Abnormal Q waves in high-risk patients are highly suggestive of a past MI. (It is estimated that approximately 30% of MIs occur without symptoms and can only be detected on routine electrocardiograms [ECGs].)

b. The presence of Q waves on a preoperative ECG in a high-risk patient, regardless of symptoms, should alert the anesthesiologist to an increased perioperative risk and the possibility of active ischemia.

c. It has not been established that information obtained from the preoperative ECG affects clinical care.

d. Although controversy exists, current recommendations for a resting 12-lead preoperative ECG include patients with at least one clinical risk factor who are undergoing a vascular surgical procedure and for patients with known CAD, peripheral vascular disease, or cerebrovascular disease who are undergoing intermediate-risk surgical procedures.

2. Noninvasive Cardiovascular Testing

a. The exercise ECG represents the most cost effective and least invasive method of detecting ischemia.

b. Pharmacologic stress thallium imaging is useful in patients who are unable to exercise.

c. In patients who cannot exercise, dopamine can be used to increase myocardial oxygen demand by increasing heart rate and blood pressure.

d. The ambulatory ECG (Holter monitoring) provides a means of continuously monitoring the ECG for significant ST-segment changes before surgery.

e. Stress echocardiography may be of value in evaluating patients with suspected CAD.

f. Dobutamine echocardiography has been found to have among the best predictive values.

g. Current recommendations are that patients with active cardiac conditions (unstable angina, congestive heart failure, arrhythmias, valve disease) should undergo noninvasive testing before noncardiac surgery.

3. Assessment of Ventricular and Valvular Function

a. Both echocardiography and radionuclide angiography may assess cardiac ejection fraction at rest and under stress, but echocardiography is less invasive and is also able to assess regional wall motion abnormalities, wall thickness, valvular function, and valve area.

b. Conflicting results exist regarding the predictive value of ejection fraction determinations.

c. It is reasonable for those with dyspnea of unknown origin and for those with current or prior heart failure with worsening dyspnea to have preoperative evaluation of left ventricular function.

d. Aortic stenosis has been associated with a poor prognosis in noncardiac surgical patients, and knowledge of valvular lesions may modify perioperative hemodynamic therapy.

4. Coronary angiography is the best method of defining coronary artery anatomy. Narrowing of the left main coronary artery may be associated with a greater perioperative risk.

B. Perioperative Coronary Interventions. The long-term survival of some patients scheduled for high-risk surgery may be enhanced by revascularization (transluminal coronary angioplasty, coronary stent placement).

C. Patients with Coronary Stents. Early surgery after coronary stent placement has been associated with adverse cardiac events. Antiplatelet therapy (aspirin, clopidogrel) requires perioperative management to balance the risk of bleeding versus stent thrombosis. The risk of regional versus general anesthesia is a consideration in the presence of antiplatelet therapy.

D. Patients with Cardiovascular Implantable Electronic Devices. The function of cardiac pacemakers and implantable defibrillators may be impaired by electromagnetic interference during surgery.

VI. PULMONARY DISEASE. Pulmonary complications (aspiration, atelectasis, bronchospasm, hypoxemia, exacerbation of chronic obstructive pulmonary disease, respiratory failure requiring mechanical ventilation) occur more frequently than cardiac complications. The site and type of surgery (thoracic and upper abdominal surgery) are the strongest predictors of pulmonary complications. The duration of surgery is a well-established risk factor for postoperative pulmonary complications with morbidity rates increasing after 2 to 3 hours.

A. Patient-related Factors. Preoperative evaluation of patients with pre-existing pulmonary disease should include assessment of the type and severity of disease, as well as its reversibility. Smoking is an important risk factor but usually cannot be influenced. Cessation of smoking for 2 days may decrease carboxyhemoglobin levels, abolish nicotine’s effects, and improve mucous clearance, but smoking cessation for at least 8 weeks is necessary to reduce the rate of postoperative pulmonary complications.

1. Asthma. Frequent use of bronchodilators, hospitalization for asthma, and the requirement for systemic steroids are all indicators of the severity of the disease.

a. After an episode of asthma, airway hyperreactivity may persist for several weeks.

b. The possibility of adrenal insufficiency is another concern in patients who have received more than a “burst and taper” of steroids in the previous 6 months.

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