Anesthesia Alert: Managing MAC

The use of deep monitored anesthesia care (MAC) during outpatient surgeries continues to increase, and for good reason. MAC eliminates the need for general anesthesia and is associated with decreased opioid use, reduced postoperative delirium and sore throat, and less pulmonary and cardiac physiologic disruption. From a facility perspective, you're accommodating patient safety and comfort with practical needs like efficient OR use and faster recoveries — and their associated cost savings.

MAC is a continuum from no sedation to depression of consciousness that can progress to general anesthesia and the need for ventilation support (Fig. 1 on opposite page). Propofol is the main drug of choice for MAC because of its favorable pharmacodynamic and pharmacokinetic profiles. Propofol is "fast on" and "fast off—" useful characteristics in maintaining patient comfort and breathing, and efficient patient throughput. Local and regional anesthetics are also often part of the MAC anesthetic mix. This synergistic effect between sedation and analgesia is hard to predict when a combination of medications are co-infused, so an increase in respiratory depression and delayed cognitive function recovery can occur.

Administering deep MAC is like walking a tight rope. Anesthesia providers must ideally maintain spontaneous breathing while preventing the need for ventilation support. Deep MAC is a great tool when properly administered, but it can be one of the most challenging anesthetics to deliver because each patient can respond differently.

Geriatric and certain ethnic populations (Asian Americans, for example) show a decreased threshold to anesthesia due to body composition and function. In general, patients may quickly transition from one level of sedation to another. As a result, anesthesia providers must be able to respond to all depths of anesthesia and have quick access to necessary equipment and supplies when the depth of sedation exceeds expectations.

As outpatient procedures continue to expand, so do the types of patient populations who undergo them. An increasing number of patients who are elderly, obese and who have a history of obstructive sleep apnea are now operated on in ambulatory ORs. For these patients, MAC can help minimize the respiratory and cardiac instability associated with a general anesthetic. However, these same patients are at increased risk of upper airway complications during anesthesia administration, including upper airway obstruction due to reduced muscle tone. In fact, most MAC-related complications result from respiratory events, which occur more often in obese, sleep apneic and elderly populations.

The most common sedation malpractice claim associated with MAC is inadequate oxygenation/ventilation with more than 80% of claims of this nature the result of brain damage or death, according to the American Society of Anesthesiologists' closed claims database. The American Association of Nurse Anesthetists Foundation's closed claims database also reports that respiratory events are the greatest cause of adverse anesthesia outcomes, with MAC identified as a contributing factor to those claims.

As the United States general population continues to grow older and obesity becomes more prevalent, the risk for upper airway complications during anesthesia in these patient groups increases as well. When administering deep MAC, anesthesia providers must be ready to intervene if upper airway obstruction occurs to prevent further morbidity or mortality.

Deep MAC is an extremely effective method of sedation when skilled anesthesia providers armed with the right medications and tools perform it on the right patients. These factors, along with strong clinical judgement and vigilant monitoring, improve post-op patient comfort, avoid the need for general anesthesia and contribute to faster and safer recoveries. OSM