Preoperative Evaluation

Cardiac risk factors dramatically increase surgical risk. Perioperative cardiac risk is typically assessed using the American College of Cardiology/American Heart Association's Revised Cardiac Risk Index ( see Figure: Algorithm for risk stratification for noncardiac surgery Algorithm for risk stratification for noncardiac surgery ). It considers the following independent predictors of cardiac risk:

Risk of cardiac complications increases with increasing risk factors:

A high-risk surgical procedure (eg, vascular surgery, open intrathoracic or intraperitoneal procedure) also independently predicts a high cardiac perioperative risk.

Patients with active cardiac symptoms (eg, of heart failure or unstable angina) have a particularly high perioperative risk. Patients with unstable angina Unstable angina Angina pectoris is a clinical syndrome of precordial discomfort or pressure due to transient myocardial ischemia without infarction. It is typically precipitated by exertion or psychologic stress... read more have about a 28% risk of perioperative myocardial infarction. In patients with stable angina, risk is proportional to their degree of exercise tolerance. Patients with active cardiac symptoms thus require thorough evaluation. For example, the cause of heart failure should be determined so that perioperative cardiac monitoring and treatment can be optimized before elective surgery. Other cardiac testing, such as stress echocardiography Stress echocardiography This photo shows a patient having echocardiography. This image shows all 4 cardiac chambers and the tricuspid and mitral valves. Echocardiography uses ultrasound waves to produce an image of... read more or even angiography Angiography Cardiac catheterization is the passage of a catheter through peripheral arteries or veins into cardiac chambers, the pulmonary artery, and coronary arteries and veins. Cardiac catheterization... read more , should be considered if there is evidence of reversible cardiac ischemia on preoperative evaluation.

Preoperative care should aim to control active disorders (eg, heart failure, diabetes) using standard treatments. Also, measures should be taken to minimize perioperative tachycardia, which can worsen heart failure and increase risk of myocardial infarction; for example, pain control should be optimized and beta-blocker therapy should be considered, especially if patients are already taking beta-blockers. Coronary revascularization should be considered for patients with unstable angina. If a heart disorder cannot be corrected before surgery or if a patient is at high risk of cardiac complications, intraoperative and sometimes preoperative monitoring with pulmonary artery catheterization Pulmonary Artery Catheter (PAC) Monitoring Some monitoring of critical care patients depends on direct observation and physical examination and is intermittent, with the frequency depending on the patient’s illness. Other monitoring... read more may be advised. Sometimes the cardiac risk outweighs the benefit of surgery. In such cases, a less invasive procedure may provide or serve as a bridge to definitive treatment (eg, tube cholecystostomy for cholecystitis) and decrease morbidity and mortality.

Incidental bacterial infections discovered preoperatively should be treated with antibiotics. However, infections should not delay surgery unless prosthetic material is being implanted; in such cases, surgery should be postponed until the infection is controlled or eliminated.

Patients with respiratory infections should be treated and have evidence that the infection has resolved before receiving inhalational anesthesia.

Viral infections with or without fever should be resolved before elective surgery is done, especially if a general anesthetic is going to be used.

Fluid and electrolyte imbalances should be corrected before surgery. Hypokalemia, hyperkalemia, hypocalcemia, and hypomagnesemia must be corrected before general anesthesia to decrease risk of potentially lethal arrhythmias. Dehydration and hypovolemia should be treated with IV fluids before general anesthesia to prevent severe hypotension on induction—blood pressure tends to fall when general anesthesia is induced.

Undernutrition Overview of Undernutrition Undernutrition is a form of malnutrition. (Malnutrition also includes overnutrition.) Undernutrition can result from inadequate ingestion of nutrients, malabsorption, impaired metabolism, loss... read more and obesity increase the risk of postoperative complications in adults. Nutritional status is assessed preoperatively using history, physical examination, and laboratory tests.

Severe nutritional risk factors include the following:

It is important to ask whether weight loss was intentional, because unintentional weight loss Involuntary Weight Loss Involuntary weight loss generally develops over weeks or months. It can be a sign of a significant physical or mental disorder and is associated with an increased risk for mortality. The causative... read more may reflect a catabolic state refractory to nutritional repletion, suggesting serious underlying pathology such as cancer.

Serum albumin is an inexpensive, widely available, and reliable indicator of undernutrition; it should be measured preoperatively in patients who may be undernourished. Values < 2.8 g/dL predict increased morbidity (including poor wound healing) and mortality. Because the half-life of serum albumin is 18 to 20 days, levels may not reflect acute undernutrition. If more acute undernutrition is suspected, a protein with a shorter half-life can be measured; for example transferrin (half-life 7 days) or transthyretin (pre-albumin; half-life 3 to 5 days). Preoperative and perioperative nutritional support with the aid of a dietitian to prevent and treat specific nutritional and electrolyte deficiencies is most likely to improve outcomes in patients whose histories of weight loss and protein levels indicate severe undernutrition (2 More Information Before elective surgical procedures, whether done in an outpatient or inpatient setting, the surgical team may consult an internist for a formal preoperative evaluation to minimize risk by identifying... read more ). In some cases, surgery can be delayed so patients can receive nutritional support, sometimes for several weeks (eg, in chronically undernourished patients, to help prevent the refeeding syndrome).

Significant obesity (body mass index > 40 kg/m²) increases perioperative mortality risk because such patients have increased risk of cardiac and pulmonary disorders (eg, hypertension, pulmonary hypertension, left ventricular hypertrophy, heart failure, coronary artery disease). Obesity is an independent risk factor for deep venous thrombosis Deep Venous Thrombosis (DVT) Deep venous thrombosis (DVT) is clotting of blood in a deep vein of an extremity (usually calf or thigh) or the pelvis. DVT is the primary cause of pulmonary embolism. DVT results from conditions... read more and pulmonary embolism; preoperative venous thromboembolism prophylaxis is indicated in most obese patients. Obesity also increases risk of postoperative wound complications (eg, fat necrosis, infection, dehiscence, and abdominal wall hernias).