Serendipity: Being in the right place at the right time
The minimum alveolar concentration (MAC) of an inhaled anesthetic preventing movement in response to a surgical incision as a measure of equipotency was “invented” in 1964 at the University of California, San Francisco. The principal advantage of MAC is that it allows the pharmacologic effects of inhaled anesthetics to be compared against each other at a similar anesthetic depth. Thus, if the hemodynamic effect (hypotension, decreased cardiac output) of anesthetic “A” is greater than that of anesthetic “B,” the anesthesiologist may elect to use “A” in patients with myocardial dysfunction. A rare side effect of a volatile anesthetic is that in some patients, malignant hyperthermia may occur with or without succinylcholine use. This phenomenon was detected in a patient in whom halothane MAC was being measured. The availability of the Severinghaus blood gas device allowed for the first ever measurement of the metabolic and respiratory acidemia that accompanies malignant hyperthermia. Copyright © 2022, the American Society of Anesthesiologists. All Rights Reserved.