American Society of Anaesthesiologists (ASA) classification

ASA Classification Definition Examples
ASA I A normal healthy patient Healthy, non-smoking, no or minimal alcohol use
ASA II A patient with mild systemic disease Mild diseases only without substantive functional limitations. Examples include (but not limited to): current smoker, social alcohol drinker, pregnancy, obesity (BMI 30 - 40), well-controlled Diabetes Mellitus/Hypertension, mild lung disease
ASA III A patient with severe systemic disease Substantive functional limitations; One or more moderate to severe diseases. Examples include (but not limited to): poorly controlled Diabetes Mellitus/Hypertension, COPD, morbid obesity (BMI > 40), active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate reduction of ejection fraction, End-Stage Renal Disease (ESRD) undergoing regularly scheduled dialysis, history (>3 months) of Myocardial infarction, Cerebrovascular accidents
ASA IV A patient with severe systemic disease that is a constant threat to life Examples include (but not limited to): recent (< 3 months) of Myocardial infarction, Cerebrovascular accidents, ongoing cardiac ischaemia or severe valve dysfunction, severe reduction of ejection fraction, sepsis, DIC, ARD or ESRD not undergoing regularly scheduled dialysis
ASA V A moribund patient who is not expected to survive without the operation Examples include (but not limited to): ruptured abdominal/thoracic aneurysm, massive trauma, intra-cranial bleed with mass effect, ischaemic bowel in the face of significant cardiac pathology or multiple organ/system dysfunction
ASA VI A declared brain-dead patient whose organs are being removed for donor purposes