Preoperative evaluation: Clinical

A preoperative evaluation is done before an individual can undergo surgery, to assess their health. This is important because surgery and anesthesia are stressful events that can exacerbate underlying diseases.

The goal of a preoperative evaluation is to identify diseases and risk factors that can increase the risk of surgery and anesthesia, and to come up with strategies to reduce that risk.

The American Society of Anesthesiologists created the ASA physical status classification system for preoperative evaluations.

This classifies individuals into six groups: 1 is a healthy person; 2 is someone with mild systemic disease; 3 is someone with severe systemic disease; 4 is someone with severe systemic disease that is a constant threat to life; 5 is a moribund person who is not expected to survive for long without the operation; and finally, 6 is a declared brain-dead person whose organs are being removed as a donor.

If the surgery is an emergency, the physical status classification is followed by “E” for emergency.

In addition to the ASA physical status, other operative risk factors include age, comorbid conditions in addition to systemic diseases, the operative procedure, the type of anesthesia, and finally the surgical team and resources.

That includes the surgical and anesthesia team, duration of surgery and anesthesia, equipment, medications, blood, and postoperative care.

The first key risk factor is age, and much of the risk associated with age is due to comorbidities like cognitive and functional impairment, malnutrition, and frailty.

Next is exercise capacity, because those with good exercise tolerance generally have low risk. Next is a complete medication history, specifically including over-the-counter, complementary, and alternative medications, which could cause an increased risk of bleeding.

Most medications should be continued up to and including the morning of the operation, but some should be discontinued preoperatively.

For example, monoamine oxidase Inhibitors or MAOIs may need to be stopped 2 weeks before surgery because of the risk of drug-drug interactions with anesthesia medications.