Definition Factors affecting MAC Significant hypoxia (below 40 mm Hg) decreases MAC. Hypothermia decreases MAC. Hyperthermia increases MAC. Hyperthyroidism slightly raises MAC (about 15%) Increasing age decreases MAC: Neonatal Halothane MAC: 1.1 70 y.o. MAC: 0.63 Circadian rhythms alter MAC + 10% Opioids reduce MAC, but there is a ceiling effect beyond which additional opioid […]