Minimum alveolar concentrations (MAC) of isoflurane with and without nitrous oxide in patients of various ages

Abstract

MAC for isoflurane alone was 1.28 ± 0.01% in the youngest group, 1.15 ± 0.06% in the middle aged group and 1.05 ± 0.05% in the oldest group. MAC's in the youngest and oldest groups differed significantly. As anticipated, addition of 70% nitrous oxide reduced the isoflurane requirement to 0.56 ± 0.07% in the youngest patients, 0.50 ± 0.07% in the middle aged patients, and 0.37 ± 0.04% in the oldest patients. The difference between MAC's in the youngest and oldest patients was significant. There was no significant difference between MAC's of men and women, either with isoflurane alone or with isoflurane nitrous oxide.