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 a poor surgical outcome. The extent of the evaluation must balance the morbidity and cost of preoperative testing against the potential for meaningfully reducing surgical morbidity. To appropriately counsel the surgeon and patient the history, physical exam, 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. Even high-risk patients undergoing low-risk procedures do not need evaluation beyond a brief screening history and exam. Emergency surgeries should not be delayed for medical consultation. For all other surgeries, the clinician should assess the patient for active heart conditions that could delay surgery. These include decompensated congestive 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 <4 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 4–5 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. One validated tool to help determine level of activity is the Duke Activity Status Index (DASI). If the patient cannot perform activities consistent with 4 METs, then it is important to determine if they are limited by dyspnea or cardiovascular disease requiring further workup. The ability to accomplish these activities without symptoms correlates with a lower perioperative risk.
Find out if complications have occurred with previous operations. Then focus the history and physical exam upon the specific areas of concern outlined below.
Assessing 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 Heart Association have published guidelines for perioperative cardiovascular evaluation based upon three factors: clinical predictors, functional capacity, and surgery-specific risks.
Determine whether the patient has angina and if so the frequency, precipitating factors, and response to rest and nitroglycerin. Especially ...