Modifiers – Anesthesia Related to CRNAs, AAs, Locum Tenens

Modifiers – Anesthesia Related to CRNAs, AAs,  Locum Tenens 

Medical direction is defined as the medical involvement of an Anesthesiologist or a qualified anesthetist (CRNA), anesthesia assistant (AA), in one, two, three or four concurrent procedures where the Anesthesiologist is physically present. Medicare requires the utilization of CRNAs and AA to be indicated with the use of a modifier.
Insurance Plans differ in their requirement for reporting the use of assistants in anesthesia care. Medicare is especially vigilant in ensuring anesthesiologists are implementing proper guidelines and correctly documenting the use of CRNAs or AAs when billing for their services.

  • AA = Anesthesia service performed personally by anesthesiologist (used for physician billing)
  • QX = Medically directed by a physician: two, three, or four concurrent procedures (used for CRNA /AA billing)
  • QK = Medical Direction of two, three, or four concurrent procedures (used for physician billing)
  • QY = Medical direction of one certified registered nurse anesthetist (CRNA) by an anesthesiologist (used for physician billing)
  • QZ = CRNA without medical direction by a physician (used for CRNA /AA billing)

In some cases that are extremely extensive like a multiple or complicated trauma case it is sometimes medically necessary for both the Anesthesiologist and the CRNA to be completely involved in a single case. Full payment to each can be made if documentation is submitted by both and the following modifiers are billed. The following circumstances must apply:

  • Trauma defined by the use of ICD9 codes from 800.00 – 929.9 or 940.0-959.9
  • Aneurysms that have ruptured
  • ICD9 codes 430 / 441.1 / 441.3 / 441.5 / 441.6
  • Massive blood transfusions exceeding 10 units of blood
  • Major body surface burns greater than 27% of BSA (use diagnosis codes 948.20-948.99)
  • Pediatric and neonatal heart surgery
  • Organ transplant (CPT 00580, 00796,00868)


Reported to indicate the use of Monitored Anesthesia Care (MAC). May be used in addition to other appropriate modifiers.

The Health Care Finance Administration has developed two temporary modifiers to report monitored anesthesia care. It is up to the carrier to recognize these modifiers for anything other than informational These modifiers went into effect on 7-1-99. However the use of the new modifier G8 with code 00300 became effective on 01-01-00 Guidelines for use of modifiers:

G8 modifier: MAC for deep, complex, complicated or markedly invasive procedures.

  • Should be used with ASA codes 00100 /00300 / 00400 / 00160 /00532/ 00920.
  • Should be reported with the appropriate anesthesia payment modifier ex. AA,QX,AB etc being listed first.
  • Don’t use with the QS modifier ex. AA, G8

G9 modifier: MAC for patients who have a history of severe cardiopulmonary conditions

  • May be used in association with QS modifier.
  • Must also have the anesthesia payment modifier placed first.
  • Must be billed with the appropriate ICD9 code to support medical necessity. Ex AA,QS,G9

If you have not received notice from your carrier as to their specific policy or the new modifiers, it would be advisable to obtain a written copy for your office.


In situations in which the regular provider is unavailable, a locum tenens can be used to provide a visit/service. The locum tenens must be the same type of provider as for whom the locum is substituting (for example, a physician can only authorize another physician as a locum tenens, an APRN/PA can only authorize another APRN/PA, etc.) and the locum tenens must be licensed in Kansas and only perform within his/her scope of license. The locum tenens must not provide services during a continuous period of longer than 60 days. For situations extending beyond 60 days, BCBSKS must be contacted to discuss billing arrangements.

In billing for services provided by a locum tenens, the claim must be filed using the NPI or specific performing provider number of the provider for whom the locum tenens is substituting and a Q6 modifier must be used. In addition, the medical record must indicate the services were provided by a locum tenens.

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