Which statement is true about the MAC value of isoflurane as provided?

Which statement is true about the MAC value of isoflurane as provided?

• A. It is 0.5-0.6%
• B. It is 1.2-1.3%
• C. It is 2.0-2.5%
• D. It is 3.0-4.0%

Answer: (B)

MAC reflects how potent an inhaled anesthetic is: it’s the alveolar concentration at which 50% of patients won’t move in response to a standard surgical stimulus. For isoflurane in adults, the MAC is about 1.15%, so a range of 1.2–1.3% matches the expected value. The other ranges are too low or too high for isoflurane and would correspond to either more potent or less potent agents. In practice, MAC varies with age, temperature, and other drugs, and clinical depth is guided by neuromonitoring and clinical signs, not MAC alone.

MAC reflects how potent an inhaled anesthetic is: it’s the alveolar concentration at which 50% of patients won’t move in response to a standard surgical stimulus. For isoflurane in adults, the MAC is about 1.15%, so a range of 1.2–1.3% matches the expected value. The other ranges are too low or too high for isoflurane and would correspond to either more potent or less potent agents. In practice, MAC varies with age, temperature, and other drugs, and clinical depth is guided by neuromonitoring and clinical signs, not MAC alone.