Introduction to Preoperative Screening
The purpose of the preoperative exam is to provide a thorough preoperative risk assessment, optimize medical comorbidities, and detect any unrecognized disease that may lead to poor surgical outcomes. The decision to extent the evaluation must balance the morbidity and costs of preoperative testing against the potential for meaningfully reducing surgical morbidity. To appropriately counsel the surgeon and patient the history, physical examination, and other studies should assess the risks for cardiovascular, neurological, venous thromboembolic, renal, pulmonary, infectious, and endocrine complications. In addition, patient-specific perioperative management strategies may be pertinent. The consultant, surgeon, and patient must balance the risks of proceeding directly to surgery against the risks of delaying a necessary procedure.
First, determine the type and urgency of the proposed surgery. Low-risk procedures do not need further evaluation given low risk of complications, even in the highest risk patient. Emergency surgeries should not be delayed for “medical clearance.”
For all other surgeries, the clinician should assess the patient for active heart conditions that could delay surgery. These include decompensated heart failure (CHF), unstable coronary syndromes (myocardial infarction [MI] within 30 days, unstable or severe angina), significant arrhythmias, and severe valvular disease (severe aortic or mitral stenosis).
If no “red flag” features are found, the patient’s functional status should be assessed. Patients who have symptoms with activities of less than four metabolic equivalents (METs) have poor functional capacity and an increased risk for perioperative cardiovascular events. One MET is defined as the energy expenditure for sitting quietly. For the average adult this is equivalent to oxygen consumption of 3.5 mL/kg body weight per minute. Activities that correlate with 4 to 5 METs of activity include mopping floors, cleaning windows, painting walls, pushing a power lawnmower, raking leaves, weeding a garden, or walking up one flight of stairs. If the patient cannot perform these activities, then it is important to determine if they are limited by dyspnea or cardiovascular disease which may require further workup. The ability to accomplish these activities without symptoms correlates with moderate or greater functional capacity and a lower perioperative risk.
Find out if complications have occurred with previous operations. Then focus the history and physical examination upon the specific areas of concern as outlined below.
Assessment of Cardiovascular and Pulmonary Risk from History
The most frequent cause of nonsurgical perioperative morbidity and mortality is acute myocardial infarction. The history is the best method of risk assessment. The American College of Cardiology and the American Hospital Association have published guidelines for perioperative cardiovascular evaluation based upon three factors: clinical predictors, functional capacity, and surgery-specific risks.
Determine whether your patient has angina and if so, find the frequency, precipitating factors, and response to rest and nitroglycerin. Especially, worrisome ...