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, flow, and volume were measured at the airway 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 microg x kg(-1) x 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.
Habre
W
W
Princess Margaret Hospital for Children and the Institute for Child Health Research, Perth, Australia.
Wildhaber
J H
JH
Sly
P D
PD
D000403:Airway Resistance / Q000187:drug effects; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D004987:Ethers / Q000494:pharmacology*; D006221:Halothane / Q000494:pharmacology*; D008170:Lung Compliance / Q000187:drug effects; D016210:Methacholine Chloride / Q000494:pharmacology*; D008738:Methyl Ethers; D012119:Respiration / Q000187:drug effects*; D000077149:Sevoflurane; D013552:Swine
D018685:Anesthetics, Inhalation; D004987:Ethers; D008738:Methyl Ethers; D016210:Methacholine Chloride; D000077149:Sevoflurane; D006221:Halothane