Question: Answer: You need to better understand the payer's anesthesia billing requirements in order to determine what modifier the payer might require. Still report modifier AA (Anesthesia services personally furnished by an anesthesiologist) if the anesthesiologist provided anesthesia for the entire case by himself. You also might need to include the appropriate physical status modifier from P1-P5 to describe the patient's physical condition during surgery. Check with the payer to see if they publish anesthesia guidelines.