Minimum alveolar concentration

Minimum alveolar concentration or MAC is the concentration, often expressed as a percentage by volume, of a vapour in the alveoli of the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) stimulus. MAC is used to compare the strengths, or potency, of anaesthetic vapours.[1] The concept of MAC was first introduced in 1965.[2]

MAC actually is a median value, not a minimum as term implies. The original paper proposed MAC as the minimal alveolar concentration,[3] which was shortly thereafter revised to minimum alveolar concentration.[4] A lower MAC value represents a more potent volatile anesthetic.

Other uses of MAC include MAC-BAR (1.7–2.0 MAC), which is the concentration required to block autonomic reflexes to nociceptive stimuli, and MAC-awake (0.3–0.5 MAC), the concentration required to block voluntary reflexes and control perceptive awareness.

  1. ^ "Policy: Ban on Use of Ether". Laboratory Animal Science Center. Archived from the original on 2008-06-09. Retrieved 2008-11-10.
  2. ^ Eger EI, Saidman LJ, Brandstater B (1965). "Minimum alveolar anesthetic concentration: a standard of anesthetic potency". Anesthesiology. 26 (6): 756–63. doi:10.1097/00000542-196511000-00010. PMID 5844267.
  3. ^ Merkel, Giles; Eger, Edmond I. (1963-05-01). "A Comparative Study of Halothane and Halopropane AnesthesiaIncluding Method for Determining Equipotency". The Journal of the American Society of Anesthesiologists. 24 (3): 346–357. doi:10.1097/00000542-196305000-00016. ISSN 0003-3022. PMID 13935000. S2CID 35750587.
  4. ^ Eger, Edmond I.; Saidman, Lawrence J.; Brandstater, Bernard (1965-11-01). "Minimum Alveolar Anesthetic ConcentrationA Standard of Anesthetic Potency". The Journal of the American Society of Anesthesiologists. 26 (6): 756–763. doi:10.1097/00000542-196511000-00010. ISSN 0003-3022. PMID 5844267.