A COMPARISON OF SEVOFLURANE WITH HALOTHANE, ENFLURANE, AND ISOFLURANE ON BRONCHOCONSTRICTION CAUSED BY HISTAMINE

This study was conducted to assess the effect of sevoflurane on lung resistance and compliance, and its responsiveness to histamine. We studied eight dogs to compare the effect of sevoflurane, isoflurane, enflurane, and halothane on bronchoconstriction caused by histamine. Baseline values of pulmonary resistance (R(L)) and dynamic pulmonary compliance (C-dyn) were measured prior to administration of histamine. Histamine 12, 4, and 8 mu g.kg(-1) were administered iv, and the values of R(L) and Cd, at the time of peak effect were recorded Under 1 or 2 MAC anaesthesia, sevoflurane as well as the other three anaesthetics had no bronchoactive effects. The four anaesthetics, including sevoflurane, demonstrated inhibitory effect on increases in R(L) and decreases in C-dyn caused by histamine. At 1 MAC anaesthesia, % changes in R(L) caused by 2, 4, or 8 mu g. kg(-1) of histamine were 38 +/- 11, 85 +/- 21, or 132 +/- 24% (mean +/- SE) for halothane, and 65 +/- 11, 132 +/- 15, or 172 +/- 19% for sevoflurane, respectively Sevoflurane was less efective than halothane in preventing increases in R(L). In preventing decreases in C-dyn sevoflurane was less effective than halothane only at 8 mu g.kg(-1) of histamine under 1 and 2 MAC anaesthesia. There was no difference in attenuating effect on changes in R(L) and C-dyn between sevoflurane and isoflurane or enflurane. We concluded that sevoflurane was less potent than halothane in attenuating changes in R(L) and C-dyn in response to iv histamine.