Question: How should I code anesthesia for weaning a patient from ECMO (extracorporeal membrane oxygenation)? Maryland Subscriber Answer: Weaning from ECMO usually is not done under anesthesia. The ECMO code is 36822 (Insertion of cannula[s] for prolonged extracorporeal circulation for cardiopulmonary insufficiency [ECMO] [separate procedure]). This crosses to anesthesia code 01844 (Anesthesia for vascular shunt, or shunt revision, any type [e.g., dialysis]). Because using anesthesia for this is not standard, append modifier -23 (Unusual anesthesia) and include supporting documentation to justify anesthesia. If the physician sedated the patient before the procedure, report 01844-52 with the base and time units as usual. If the patient is already heavily sedated prior to weaning, some coders recommend reporting the applicable time units, but not the code's base units.