A review of ASA physical status - historical perspectives and modern developments.

The American Society of Anesthesiologists (ASA) physical status is a tool commonly used to classify a patient's physical fitness before surgery. Since its introduction in 1941 it has undergone very few modifications to improve its reliability and to eliminate subjectivity, despite vast changes in both surgical and anaesthetic technique. We present the history of the ASA physical status and review the literature on its applicability to contemporary anaesthetic practice.