Letter to the Editor:
Uriel Yodfat, MD
Monitored anesthesia care (MAC) is clearly defined by the American Society of Anesthesiologists (ASA) House of Delegates.1 This definition is often poorly understood by surgeons, patients and, at times, anesthesia providers. This lack of clarity is what brought about the need for the ASA statement distinguishing between MAC, various forms of sedation it might encompass and the expertise needed to administer it.
In modern-day clinical anesthesia practice, one finds that in the majority of cases performed under MAC, a state of complete unconsciousness occurs, to a point that reminds me of a different MAC—minimal alveolar concentration—used in general anesthesia. The result is that it is unclear which anesthetic technique was used: MAC or general anesthesia. The ASA’s own definition states, “General anesthesia is a drug-induced loss of consciousness during which an individual is not arousable, even by painful stimulation.”2
It appears that when assessing the state of consciousness for most of our MAC cases, a state of general anesthesia has been achieved for at least a meaningful portion of the procedure.
There are probably several explanations as to why our sedation has gotten so deep. Partly because of popular demand from both surgeon and patient (“the patient is moving, do something” and “I don’t want to hear or see anything”) and partly because our own practice has developed excellent early detection of apnea and techniques for treating it quickly and effectively (e.g., ventilatory support, airway devices including laryngeal mask airways and endotracheal intubation as a last resort), allowing us to comply with the wishes of surgeons and patients safely while distinguishing our services from “conscious sedation” available from nonanesthesia providers.
These blurred lines between various anesthetic techniques bring about questions:
- Is there really a principal difference between general anesthesia and MAC?
- Should we re-evaluate our existing terminology?
- Are we still using terms that no longer describe our modern practice?
- Should we find new and improved terms to define our practice?
- Is it still relevant to think of a general anesthetic in terms of endotracheal intubation or a laryngeal mask airway device?
- What about an oral (or nasal) airway, which is often used in cases considered MAC?
- Is there really a clear line drawn between a laryngeal mask airway and a regular oral airway to help differentiate general anesthesia from MAC, as is commonly seen in operating rooms across the country?
- Is there any difference between MAC and general anesthesia, and if so, how is it defined?
References
- American Society of Anesthesiologists. Distinguishing monitored anesthesia care (“mac”) from moderate sedation/analgesia (conscious sedation). Committee of Origin: Economics. (Approved by the ASA House of Delegates on October 27, 2004, last amended on October 21, 2009, and reaffirmed on October 16, 2013).asahq.org/?~/?media/?Sites/?ASAHQ/?Files/?Public/?Resources/?standards-guidelines/?distinguishing-monitored-anesthesia-care-from-moderate-sedation-analgesia.pdf.
- American Society of Anesthesiologists. Continuum of depth of sedation: definition of general anesthesia and levels of sedation/analgesia. Committee of Origin: Quality management and departmental administration. (Approved by the ASA House of Delegates on October 13, 1999, and last amended on October 15, 2014).asahq.org/?~/?media/?Sites/?ASAHQ/?Files/?Public/?Resources/?standards-guidelines/?continuum-of-depth-of-sedation-definition-of-general-anesthesia-and-levels-of-sedation-analgesia.pdf.
Dr. Yodfat is an anesthesiologist with Riverside Anesthesia Associates, and clinical assistant professor at Penn State Milton S. Hershey Medical Center, in Hershey, PA.