SEVOFLURANE AND ISOFLURANE PROTECT AGAINST BRONCHOSPASM IN DOGS

Background Halothane and isoflurane have been shown to be effective in reversing bronchoconstriction; however, the effects of sevoflurane have not been well defined. we studied whether sevoflurane, compared with isoflurane, attenuates bronchospasm in dogs. Methods: Twenty-four dogs sensitized to Ascaris suum were assigned to three groups: control (n = 8), sevoflurane (n = 8), or isoflurane (n = 8). In all dogs, anesthesia was induced with pentobarbital. In the sevoflurane and isoflurane groups, the volatile anesthetics were administered at an end-tidal anesthetic concentration of 1 MAC throughout the study. After measurement of pulmonary resistance (R(L)) and dynamic pulmonary compliance (C-dyn) at baseline, A. suum antigen was administered intravenously into the systemic circulation to induce anaphylaxis, and R(L) and C-dyn were recorded continuously for 120 min after antigen challenge. Results: Effects on R(L) and C-dyn were maximal 5 min after the start of systemic administration of antigen in all groups. Both 1 MAC sevoflurane and 1 MAC isoflurane significantly attenuated the increase in R(L) provoked by antigen challenge, but the attenuation from 10 to 15 min after challenge in the sevoflurane group was not significantly different from that in the control group. There was no significant difference in R(L) between sevoflurane and isoflurane. For both sevoflurane and isoflurane, attenuation of the decrease in C-dyn was not statistically significant. There was no significant difference in C-dyn between sevoflurane and isoflurane. Conclusions: Sevoflurane is as effective as isoflurane in attenuating bronchoconstriction associated with anaphylaxis in dogs. Sevoflurane may be a useful alternative to halothane, enflurane, or isoflurane in the treatment of bronchospasm in asthma or anaphylaxis.