Time- and Dose-Dependent Effects of Desflurane in Sensitized Airways.

BACKGROUND

Although the bronchodilatory actions of volatile anesthetics, such as halothane, isoflurane, and sevoflurane, have been well documented in previous studies, the properties of desflurane remain controversial. The aim of this study was to investigate the effects of desflurane at different concentrations and durations in an ovalbumin-sensitized guinea pig model of airway hyper-responsiveness.

METHODS

Ovalbumin-sensitized animals (n = 176) were randomly assigned to 5 groups according to the minimum alveolar concentration (MAC) of desflurane they received: 0.0, 0.5, 1.0, 1.5, and 2.0 MAC. Total lung resistance in vivo, airway smooth muscle tension in vitro, and intracellular cyclic adenosine monophosphate (AMP) levels were measured to evaluate the effects of desflurane.

RESULTS

In 5 sensitized groups, total lung resistance increased from baseline to peak at approximately 8 minutes and then decreased slowly until about 17 minutes with extended administration of desflurane. Desflurane dose-dependently increased total lung resistance with or without incremental doses of acetylcholine and reduced muscle tension with increasing concentrations of carbacholine. Cyclic AMP levels were increased by desflurane: at the 60-minute time point, cyclic AMP concentrations (means ± SD) with 0.5 MAC (1.96 ± 0.40) and 1.0 MAC (2.11 ± 0.50) desflurane were higher than those at the 8-minute time point (1.11 ± 0.23 and 1.32 ± 0.32).

CONCLUSIONS

Desflurane exerted time- and dose-dependent effects and could be used at 0.5 and 1.0 MAC concentrations without significant bronchoconstriction in ovalbumin-sensitized guinea pigs. Cyclic AMP-mediated airway smooth muscle relaxation might be one mechanism by which desflurane induces bronchodilation.