The effect of midazolam on the recovery quality, recovery time and the minimum alveolar concentration for extubation in the isoflurane-anesthetized pig

Abstract

There are no reported studies evaluating the effect of midazolam on recovery quality, recovery time or minimum alveolar concentration (MAC) at which extubation occurs (MACextubation). Our hypotheses were that midazolam administered prior to recovery would decrease MACextubation, prolong recovery time but provide a smoother recovery. Sixteen Yorkshire pigs were anesthetized with isoflurane for approximately 5 h. The end-tidal isoflurane concentration was then stabilized at 1.4% for 20 min. Pigs were randomly assigned to receive midazolam or saline. The vaporizer was decreased by 10% every 10 min until extubation. Pigs were declared awake by a blinded observer and were assigned a recovery score by the same observer. Mean MACextubation was not significantly different for pigs receiving saline prior to recovery compared with those pigs receiving midazolam. The overall mean MACextubation for both groups was 0.6 ± 0.4 vol%. Time to extubation was not significantly longer with midazolam (124 ± 36 min) compared with the saline group (96 ± 61 min; P = 0.09). Recovery score was not significantly different between groups (midazolam, 0.86 ± 1.1; saline 0.5 ± 0.5; P = 0.26). In conclusion, midazolam did not affect MACextubation. There was no advantage of administering midazolam in the recovery period when performing step-down titration of isoflurane anesthesia.