Question: An anesthesiologist was involved with a case for 18 hours. He was personally performing anesthesia for the first 10 hours, then was relieved for the last eight hours by another anesthesiologist who was performing -AD (Medical supervision by a physician: more than four concurrent anesthesia procedures). How should the case be billed? New Jersey Subscriber Answer: Bill the case as two separate claims, based on how the services were provided: -AA (Anesthesia services performed personally by anesthesiologist) for the first 10 hours and -AD for the following eight hours. Submit the claim on paper so you can send copies of all reports and write a letter of explanation to the carrier.