ANESTHETIC POTENCY OF DESFLURANE IN THE HORSE - DETERMINATION OF THE MINIMUM ALVEOLAR CONCENTRATION

Objective-To determine the minimum alveolar concentration (MAC) of des flurane (DES) in the horse. Study Design-Prospective study. Animals-Si x healthy adult horses (three males and three females) weighing 370 +/ - 16 kg and aged 9 +/- 2 years old. Methods-Anesthesia was induced wit h DES vaporized in oxygen via a face mask connected to a large-animal, semiclosed anesthetic circle system. The horses were endotracheally i ntubated and positioned in right lateral recumbency. Inspired and end- tidal DES were monitored using a calibrated Ohmeda RGM 5250 multigas a nalyzer (Ohmeda-BOC, Spain). The MAC of desflurane that prevented gros s purposeful movement in response to 60 seconds of noxious electrical stimulation of oral mucous membranes was determined. Results-The time from the start of DES administration to lateral recumbency was 6.1 +/- 0.9 min. The MAC of DES in these horses was 7.6 +/- 0.4%. Time requir ed for the animal to regain sternal recumbency after 98 +/- 4 minutes of anesthesia was 6.6 +/- 0.5 minutes and the time to standing was 14. 3 +/- 2.7 minutes. Conclusions-The MAC of desflurane in these horses w as 7.6 +/- 0.4%. DES provided a rapid induction to, and recovery from, anesthesia. Clinical Relevance-Desflurane offers the potential for mo re precise control during anesthesia, and may allow a faster and uneve ntful recovery. It is important to know the MAC of an inhalant to use it clinically. (C) Copyright 1997 by The American College of Veterinar y Surgeons.