Prevention of methacholine-induced changes in respiratory mechanics in piglets: A comparison of sevoflurane and halothane

Background: Sevoflurane is a new volatile anesthetic agent that may be a useful alternative to halothane for anesthesia in children. However, there is insufficient information about its effects on respiratory mechanics, particularly in the presence of constrictor stimuli. Methods: Eighteen piglets had anesthesia induced and maintained with either pentobarbital (control: n = 8), 1 minimum alveolar concentration (MAC) sevoflurane (sevo: n = 5), or 1 MAC halothane (halo: n = 5). Pressure, now, and volume were measured at the ah-way opening and used to calculate lung compliance (C-L) and resistance (R-L). Resistance was partitioned into airway (Raw) and parenchymal (Vti) components using alveolar pressure. Methacholine was infused intravenously in a dose sufficient (15 mu g . kg(-1). h(-1)) to approximately double R-L. Results: The increase in R-L seen in the control group was almost entirely due to an increase in Vti. Sevoflurane and halothane prevented the increase in R-L and Vti (both P < 0.02) and the decrease in C-L (both P < 0.02). Conclusions: Sevoflurane and halothane can prevent methacholine-induced changes in lung function.