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 (RL) and dynamic pulmonary compliance (Cdyn) at baseline, A. suum antigen was administered intravenously into the systemic circulation to induce anaphylaxis, and RL and Cdyn were recorded continuously for 120 min after antigen challenge.

RESULTS

Effects on RL and Cdyn 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 RL 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 RL between sevoflurane and isoflurane. For both sevoflurane and isoflurane, attenuation of the decrease in Cdyn was not statistically significant. There was no significant difference in Cdyn 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.