The minimum alveolar concentration of nitrous oxide in man.

The potency and anesthetic state produced by nitrous oxide alone were investigated in order to clarify its contribution to the effect of other anesthetic agents. Seven volunteers anesthetized with 1.55 atm absolute N2O in a pressure chamber displayed muscle rigidity with jerking movements, labored and rapid breathing, sweating, and dilated pupils. At 1.1 atm absolute N2O, relaxation and quiescence occurred, sweating ceased, and pupil size decreased. Determination of MAC (using tetanic electrical impulses as the noxious stimulus) produced a mean value of 1.04 +/- 0.10 (SE) atm absolute. All subjects complained of nausea and vomiting after anesthesia.