In inhalational anesthesia, what does MAC stand for?

• A. Maximum Alveolar Concentration
• B. Mean Alveolar Concentration
• C. Minimum Alveolar Concentration
• D. Monitored Anesthesia Concentration

Answer: (C)

Inhaled anesthetic potency is described using a standard measure, MAC. This stands for the alveolar concentration at which 50% of patients do not move in response to a standardized surgical stimulus. It’s a statistic that links the amount of drug in the lungs to the likelihood of immobility, reflecting the brain concentration needed to achieve that effect. Because a lower MAC means the agent is more potent, MAC provides a convenient way to compare different inhaled anesthetics and guide dosing across patients.

The other phrases don’t fit because they describe different concepts. Maximum Alveolar Concentration would imply the highest possible concentration needed, which isn’t how potency is defined. Mean Alveolar Concentration isn’t the standard reference used for predicting movement response. Monitored Anesthesia Concentration is a monitoring term (end-tidal concentration) rather than the potency metric represented by MAC.