JSAL Anesthesia Practice Test

Minimum Alveolar Concentration (MAC) expresses how potent an inhaled anesthetic is. It’s the alveolar concentration needed to prevent movement in 50% of subjects in response to a standardized painful stimulus. The lower the MAC, the more potent the drug. For isoflurane in common veterinary species, the MAC is about 1.2–1.3%, which fits a moderate potency profile. This value is a baseline; MAC can shift with species, age, temperature, and what other drugs are given. In practice, adding other anesthetics or analgesics (like opioids or sedatives) often lowers the required isoflurane MAC, meaning you can maintain anesthesia with a lighter concentration. Why the other statements don’t fit: a MAC of 0.5–0.8% would imply greater potency than isoflurane typically has, which isn’t supported by veterinary data. A MAC of 2.0–2.5% would indicate much weaker potency, also inaccurate for isoflurane. And isoflurane is routinely used in veterinary surgery, so saying it’s never used isn’t correct.