A way to describe the pre¬ operative condition of a patient, used by anesthesiologists. It was originally devised by the American Society of Anesthetists (predecessor of the American Society of Anesthesiologists) to permit collection and tabulation of statistical data in anesthesia. It has now become a routine, international “shorthand” for anesthesiologists to use in assessing a patient prior to surgery. There are five classes: (1) normal, healthy patient; (2) patient with mild systemic disease; (3) patient with severe systemic disease that limits activity but is not incapacitating; (4) a patient with an incapacitating disease that is a constant threat to life; (5) a moribund patient who is not expected to survive for 24 hours with or without an operation. Also called ASA physical classification, PS score, PS grade.