MAC or Monitored Anesthesia Care is a time-based reimbursable service, which has to be reported using thecorrect monitored anesthesia modifier, QS, G8 or G9 attached to the appropriate CPT code for anesthesia services. MAC is defined as “a planned procedure during which the patient undergoes local anesthesia together with sedation and analgesia.” MAC must be proved medically necessary if it is to be reimbursed.

MAC is reimbursed only when the following requirements are met:

The service has to be properly coded
All documentation has to be clear, meeting all requirements
The service provided is medically necessary
All facility requirements are satisfied

An anesthesiologist or CRNA is reimbursed for monitored anesthesia care provided he/she meets the following requirements:

Prescribes the anesthesia care required
Is physically present throughout when participating in the case
Observes all facility regulations regarding anesthesia services
Provides indicated postoperative anesthesia care
Administers analgesics, sedatives, anesthetic agents, hypnotics or other medications in view of patient safety
Performs a pre-anesthetic examination and evaluation
Identifies and treats clinical problems that may occur during the procedure

MAC is not included in moderate (conscious) sedation; moderate sedation is usually reported with CPT codes 99143-99150.

The QS, G8 and G9 MAC modifiers are usually used for informational purposes, and are to be used in the position of the second modifier. The first modifier position is to be filled in using a pricing anesthesia modifier such as AA, QX, AB.

QS—Monitored anesthesia care (MAC). It is used in addition to other appropriate modifiers.
G8—used to report MAC provided for deep, complex, complicated or significantly invasive surgical procedures
G9 – to report MAC provided for a patient with a history of severe cardiopulmonary condition

The G8 modifier can be used only with six anesthesia CPT codes. These are:

00300 – to report anesthesia for procedures on the integumentary system of the neck, including subcutaneous tissue
00100, 00400, 00160 – to report surgical procedures on the face, neck and breast
00532 –  to report procedures for access to central venous circulation
00920 –  to report procedures on male external genitalia

The modifier G8 is used in the place of modifier QS and should not be used in conjunction with it. Usually, G8 does not require an ICD-9-CM code to support medical necessity, mainly because the surgical procedure itself rather than the condition of the patient justifies MAC.

The G9 modifier is used instead of the QS modifier, and the QS modifier should not be therefore listed on the claim. The G9 modifier has to be supported by an ICD-9-CM code to prove medical necessity.

In anesthesia claims, one of these three MAC modifiers have to be used when reporting a MAC anesthesia service listed in the CPT/HCPCS section. Otherwise, the claim might be denied.

The Level II modifiers or the HCPCS/national modifiers signified by two alphabetic or alphanumeric digits are recognized by carriers on a national level. The modifiers G8 and G9 are not required by all carriers, in such cases MAC should be reported using the QS modifier. Though included as a ‘statistical reporting’ modifier initially, the QS modifier is now mandatory on anesthesia claims. When billing for anesthesia, it is important for coders to have clear knowledge about the policies of the particular state. Anesthesia medical coding is quite complex, since private carrier requirements and local medical review policies on the use of anesthesia modifiers vary from one state to another. Accurate coding can be ensured only with complete awareness regarding the specific policies of insurance carriers in particular states.

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