Comparison between Minimum Alveolar Concentration and Minimum Alveolar Concentration for Blunting Adrenergic Response after Administration of Sevoflurane in Cats

Objectives: Minimum alveolar concentration (MAC) is defined as the alveolar concentration of anesthetic at 1 atmosphere that produces immobility in 50% of subjects exposed to a noxious stimulus. There is limited information regarding the MAC of sevoflurane required for blunting adrenergic responses (MAC-BAR) in cats. The aim of this study was to compare the MAC and MAC-BAR of sevoflurane required to prevent autonomic responses and purposeful movements in cats. Methods: Six adult healthy domestic short-haired catswere anesthetized with sevoflurane. The MAC and MAC-BAR values for sevoflurane were determined by judging the cats' responses to a noxious electrical stimulus (50 V, 50 Hz, 10 msec) applied to the ventral side of the tail base. Results: The difference between the MAC and MAC-BAR values for sevoflurane was not statistically significant. Conclusions and Relevance: These results suggest that autonomic responses are prevented by anesthetic concentrations of sevoflurane at which purposeful movements are absent. Detrimental cardiovascular side effects, such as hypotension and impaired cardiac contractility, can occur easily in cat's anesthetized using sevoflurane.