Clinical Overview: The ASA Classification
The American Society of Anesthesiologists (ASA) Physical Status Classification System is a simple but powerful system to categorize a patient's physiological state before surgery. It helps clinicians communicate about a patient's overall health and is strongly correlated with perioperative risk.
The Six Classes
- ASA I: A normal healthy patient (non-smoker, no/minimal alcohol).
- ASA II: A patient with mild systemic disease (e.g., controlled HTN, mild obesity, smoker).
- ASA III: A patient with severe systemic disease (e.g., poorly controlled DM, COPD, morbid obesity).
- ASA IV: A patient with severe systemic disease that is a constant threat to life (e.g., recent MI, ongoing ischemia, end-stage renal disease).
- ASA V: A moribund patient who is not expected to survive without the operation (e.g., ruptured AAA).
- ASA VI: A declared brain-dead patient whose organs are being removed for donor purposes.
The 'E' Modifier
ASA Physical Status = Class (I-VI) [+ E if Emergency]
Where:
ASA I-II=
Low perioperative riskASA III-V=
Significantly increased riskIf a surgery is an emergency (where a delay in treatment would significantly increase the threat to life or limb), the letter E is added to the class (e.g., ASA IIIE).