Comparison of MAC and the Rate of Rise of Alveolar Concentration of Sevoflurane with Halothane and Isoflurane in the Dog

The anesthetic requirements for sevoflurane, isoflurane, and halothane were determined in mongrel dogs. The MACs (minimum alveolar concentration) of sevoflurane, isoflurane, and halothane were 2.36 +/- 0.46% (n = 18), 1.39 +/- 0.25% (n = 10), and 0.89 +/- 0.20% (n = 12), respectively (mean +/- SD). In agreement with sevoflurane's low blood/gas partition coefficient (0.6), the rate of rise of alveolar concentration toward that inspired (FA/FI) for sevoflurane was significantly faster than that for either halothane or isoflurane. Thirty seconds after breathing a constant inspired concentration FA/FI was 0.75 for sevoflurane, which was 2.96 times higher than that with halothane (0.25 +/- 0.02) and 1.29 times higher than that with isoflurane (0.6 +/- 0.05). Induction with sevoflurane was smooth, with no struggling nor excessive salivation.