| Modifier | Description |
|---|---|
| AA | Anesthesia services personally performed by the anesthesiologist |
| AD | Supervision, more than four procedures |
| QK | Medical direction of two, three, or four concurrent anesthesia procedures |
| QX | Qualified non-physician anesthetist with medical direction by a physician |
| QY | Medical direction of one CRNA/AA by an anesthesiologist |
| QZ | Certified registered nurse anesthetist (CRNA) without medical direction by a physician |
| QS | Monitored anesthesia care (MAC) services (can be billed by a qualified nonphysician anesthetist or physician) |
| G8 | Deep complex complicated, or markedly invasive surgical procedures |
| G9 | Appended with an anesthesia code to indicate that the patient has a history of a severe cardiopulmonary condition |
| P1 | A normal healthy patient |
| P2 | A patient with mild systemic disease |
| P3 | A patient with severe systemic disease |
| P4 | A Patient with severe systemic disease that is a constant threat to life |
| P5 | A moribund patient who is not expected to survive without the operation |
| P6 | A declared brain-dead patient whose organs are being removed for donor purposes |
| GC | These services have been performed by a resident under the direction of a teaching physician. Note: This modifier is reported by the teaching physician to indicate they rendered the service in compliance with the teaching physician requirements. The teaching anesthesiologist should report modifiers “AA” and “GC” (certification modifier). |
| 23 | Unusual anesthesia Note: Using modifier 23 attests that proper documentation is on file to support the unusual anesthesia service. |
| 33 | Preventive services: When the primary purpose of the service is the delivery of an evidence based service in accordance with a U.S. Preventive Services Task Force A or B rating in effect and other preventive services identified in preventive services mandates (legislative or regulatory), the service may be identified by adding 33 to the procedure. |