The pharmacokinetics of sevoflurane and isoflurane during their administration are defined as the ratio of end-tidal anesthetic concentration (FA) to inspired anesthetic concentration FI (ie, FA/FI) (mean ± SD). Consistent with its relative blood/gas partition coefficient, the FA/FI of sevoflurane increases more rapidly than that of isoflurane or halothane but slower than that of N2O or desflurane.