Minimum alveolar concentration (MAC) of xenon in intubated swine.
BACKGROUND
The minimum alveolar concentration (MAC) is a traditional index of the hypnotic potency of an inhalational anaesthetic. To investigate the anaesthetic as well as the unwanted effects of xenon (Xe) in a swine model, it is useful to know MAC(Xe).


METHODS
The study was performed using ten swine (weight 27.8-35.4 kg) anaesthetized with halothane and Xe 0, 15, 30, 40, 50 and 65% in oxygen. With each Xe concentration, various concentrations of halothane were administered in a step-by-step design. For each combination, a supramaximal pain stimulus (claw clamp) was applied and the appearance of a withdrawal reaction was recorded. The MAC(Xe) with halothane was calculated using a logistic regression model.


RESULTS
During stable ventilation, haemodynamics and temperature, MAC(Xe) value was determined as 119 vol. % (95% confidence limits 103-135).


CONCLUSIONS
MAC(Xe) in swine was calculated by extrapolation of a logistic regression model. Its theoretical value is 119 vol. %.
Hecker
K E
KE
Department of Anaesthesiology, Klinikum der RWTH Aachen, Pauwelsstr. 30, D-52074 Aachen, Germany. klaus.hecker@post.rwth-aachen.de
Horn
N
N
Baumert
J H
JH
Reyle-Hahn
S M
SM
Heussen
N
N
Rossaint
R
R
D000764:Anesthesia, Closed-Circuit; D019162:Anesthetics, Combined / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006221:Halothane / Q000494:pharmacology; D007442:Intubation, Intratracheal; D016015:Logistic Models; D017288:Pain Threshold / Q000187:drug effects; D013552:Swine; D014978:Xenon / Q000493:pharmacokinetics*
D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D014978:Xenon; D006221:Halothane