Letter to the Editor
Ivan Hronek, MD
The term “monitored anesthesia care” (MAC) was introduced in 19861 to improve on the term “anesthesia standby” used up until then, with the term “standby” being hard to defend when payment was requested. However, the words monitored anesthesia care do not discriminate by themselves from other types of anesthesia as any anesthesia care has to be monitored. The name of a procedure should describe its contents, but the term MAC informs that there will be monitoring and an anesthesia provider will be present but it does not say sedation may be given, and so it is impossible to be understood without further explanation.
More importantly, the term MAC is supposed to be distinct from general anesthesia (GA). However, depth of sedation and transition to GA has been described as a continuum by the American Society of Anesthesiologists (ASA),2and it is well accepted that, after an equivalent weight-based dose of an anesthetic, some patients are sedated whereas others, due to interindividual sensitivity differences, are under GA. The ASA Position Statement on MAC3states that when the patient loses the ability to respond purposefully, then the anesthesia is GA. Going by that definition, practitioners correctly point out that during MAC, there routinely are periods of GA. Using the term GA for cases that are MAC is not accurate either, as during many MACs, we do not guarantee loss of purposeful response or awareness at all times during the procedure.
In light of this criticism, there are two ways to redefine the term MAC:
- Widen the MAC definition to include short periods of GA. The current definition of MAC already includes an anesthesiologist’s choice of monitoring only light, moderate and deep sedation. If it is considered acceptable that a term may include approaches that are not included in its name, short periods of GA could be added to its definition. We would continue to live with the fact that, for everyone’s understanding, we must add regular-language terms, such as general anesthesia, sedation, nerve block and their combinations. Stretching the MAC definition would not require changes in the existing billing or surgical and nursing software, which contain MAC as an option and do not contain sedation or the possibility of combining them.
- Narrow the definition of MAC to describe situations in which there actually is monitoringonlyand no medication is given. The advantage here is that the term MAC would actually mean what it says—monitored anesthesia care only.
There would be the following anesthesia options and their combinations:
- General anesthesia
- Sedation or anesthesia sedation—defined as use of medication
- MAC—defined as monitoring only (but still including preoperative evaluation, psychological support and option for immediate conversion to other types of anesthesia)
- Regional anesthesia
Combinations would clearly describe what actually occurred with both planned or converted MAC/sedation, MAC/sedation/GA, MAC/GA, regional/sedation, regional/MAC and regional/GA. This would also more succinctly describe regional anesthesia cases in which the question of the type of anesthesia used often comes up. As an example, the new description of the current term MAC in which periods of sedation as well as GA occur would be a combination: Sedation/GA Mix.
Let’s ask the ASA to consider one of such redefinitions. Until any change is made, though, I believe we need to describe what actually happens, so if there is a level of nonresponsiveness to pain during a procedure that started as MAC, we need to record that as both MAC and GA, for reasons of clarity and legality.
Dr. Hronek is an anesthesiologist with Tarzana Anesthesia Medical Group in Los Angeles and moderates the LinkedIn group Anesthideas.
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