Effects of Hypothermia on Halothane MAC and Isoflurane MAC in the Rat

Abstract

MAC was determined in tracheotomized rats for halothane (5 rats) and inoflurane (3 rats) at 37, 32, and 27 C. Rectilinear decreases in MAC occurred with both agents. The change with halothane (4.82 per cent per degree) did not differ significantly from that seen with isoflurane (5.28 per cent per degree). We conclude that animals anesthetized with isoflurane conform to the pattern of linear MAC decreases with decreases in temperature described for other anesthetics. The MAC decrease for isoflurane is greater than those found with fluroxene, ether, or cyclopropane.