Anesthesia Definitions

This document defines terms associated with the direction and supervision of eligible certified registered nurse anesthetists (CRNA) by anesthesiologists and surgeons.

Personally Performed Anesthesia Services

Anesthesia procedures that are personally performed by either an anesthesiologist or CRNA.

Medical Direction of Anesthesia Services

Medical direction occurs when an anesthesiologist is involved in two, three or four concurrent anesthesia procedures or a single anesthesia procedure with a qualified anesthetist. For each anesthesia procedure, the anesthesiologist must do the following seven services:

If one or more of the above services are not performed by the anesthesiologist, the service is not considered medical direction.

Ordinarily, anesthesiologist should not furnish additional services to other patients while concurrently directing the administration of anesthesia. The anesthesiologist can, however, provide any of the following services to other patients while medically directing the administration of anesthesia without affecting their ability to administer medical direction.

Medical Supervision of Anesthesia Services

Medical supervision occurs when an anesthesiologist is involved in five or more concurrent anesthesia procedures.

Medical supervision also occurs when the seven required services under medical direction are not performed by an anesthesiologist. This might occur in cases when the anesthesiologist:

Monitored Anesthesia Care (MAC)

Monitored anesthesia care is the intraoperative (i.e., during surgery) monitoring by an anesthesiologist or qualified individual under the direction of an anesthesiologist of a patient's vital physiological signs, in anticipation of:

Monitored anesthesia care includes the performance of the following by the anesthesiologists or qualified individual under the direction of an anesthesiologist:

The anesthesiologist, or qualified individual under the direction of an anesthesiologist, administering monitored anesthesia care must be continuously present to monitor the patient and provide anesthesia care.

The monitored anesthesia care service must be reasonable and medically necessary under the given circumstances.

Anesthesia Standby

Anesthesia standby occurs when the anesthesiologists, or the CRNA, is available in the facility in the event they are needed for a procedure requiring anesthesia (e.g., available in the facility in case of obstetric complications - breech presentation, twins, and trial of instrumental delivery), but is not physically present or providing services. Anesthesia standby is considered a part of any anesthesia services provided during the standby period.

Medical Supervision by a Surgeon

In some small institutions, nurse anesthetist performance is supervised by the operating practitioner (i.e., surgeon) who assumes responsibility for satisfying the requirement found in the state health codes and federal Medicare regulations pertaining to the supervision of nurse anesthetists. Supervision services provided by the operating physician are considered part of the surgical service provided.


American Society of Anesthesiologists, "Re: Medicare Programs; Revisions to Payment Policies Under the Physicians Fee Schedule for Calendar Year 2001; HCFA-1120-P." September 15, 2000. Accessed 9/27/00. Available at:

CIGNA HealthCare Medicare Administration, "Medicare Part B Carrier - Tennessee Local Medical Review Policy - Update." September 15, 1999. Accessed 10/25/00. Available at:

CIGNA Medicare Spring Workshop, Course materials. 1997 & 2000; published and sponsored by CIGNA.

Practical Anesthesia Billing, Coding & Compliance 2000, Course materials, Anesthesia 101: Anesthesia Billing for Beginners. October 19-20, 2000; published and sponsored by: Anesthesia Answer Book Anesthesia & Pain Practice Coder.

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