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With an aging and increasingly obese population, patients with significant comorbidities present for surgery. Although age per se is not a factor in determining candidacy for ambulatory procedures, each patient must be considered in the context of his or her comorbidities, the type of surgery to be performed, and the expected response to anesthesia. First developed in 1963, the American Society of Anesthesiologists’ (ASA) physical status classification system (Table 66-1) summarizes the physiologic fitness of each patient prior to surgery. It serves as a means of communication between health-care providers and is used for record-keeping.

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TABLE 66-1   ASA’s Physical Status Classification of Patients1 

In general, ambulatory surgeries should be of a complexity and duration such that one could reasonably assume that the patient will make an expeditious recovery. Assessment of the patient’s ASA physical status and completion of a thorough history and physical examination are crucial in the screening of patients selected for ambulatory or office-based surgery. ASA 4 and 5 patients normally would not be candidates for ambulatory surgery, whereas ASA 1 and 2 patients would be prime candidates for such surgery. ASA 3 patients with diabetes, hypertension, and stable coronary artery disease would not be precluded from an ambulatory procedure, provided their diseases are well controlled. Ultimately, the surgeon and anesthesiologist must identify patients for whom an ambulatory or office-based setting is likely to provide benefits (eg, convenience, reduced costs, and charges) that outweigh risks (eg, the lack of immediate availability of all hospital services, such as a cardiac catheterization laboratory, emergency cardiovascular stents, assistance with airway rescue, and rapid consultation).


Criticism of the ASA physical status scale is primarily due to its exclusion of age and difficulty of intubation. A study of 1095 patients undergoing total hip replacement, prostatectomy, or cholecystectomy found that both age and ASA physical status accurately predicts postoperative morbidity and mortality. Although it does not predict operative risk, the ASA physical status scale remains a useful application for all ...

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