Emergence and recovery in children after desflurane and isoflurane anaesthesia: effect of anaesthetic duration

Background. We hypothesized that increasing duration of inhalationanaesthesia is associated with slower emergence and recoveryin children, and that this effect would be less marked withdesflurane in comparison with isoflurane. Methods. Fifty-four infants and children assigned in groupsaccording to age and expected length of operation were prospectivelyrandomized to receive either isoflurane (I) or desflurane (D)for anaesthesia. After standard induction, the anaesthesia wasmaintained using an age-related 1.0 minimum alveolar concentration(MAC) equivalent for either agent in air and oxygen. Local analgesiawas used as appropriate. End-tidal volatile agent concentrationwas recorded until extubation. Clinical evaluation of recoverywas made by observers, blinded to group allocation. Results. For patients <4 yr of age, the median (95% CI) timesin minutes to first movement 5.27 (D), 9.22 (I)], eye opening9.42(D), 13.3(I)] and extubation 7.18 (D), 12.5 (I)] weresignificantly shorter (P<0.05) for desflurane. In the group>4 yr of age, the median (95% CI) times in minutes to firstmovement 4.42 (D), 11.6 (I)], eye opening 8.55(D), 18.0(I)]and extubation 7.08 (D), 16.7 (I)] were significantly shorter(P<0.001) for desflurane. Times to leave recovery were notsignificantly different for the group <4 yr of age, but weresignificantly shorter for desflurane in the group >4 yr ofage (P<0.01). The isoflurane, but not desflurane, had a time-dependenteffect on arousal. There were no significant differences inincidence of airway irritation or emergence delirium betweenthe two agents. Conclusions. The rate of recovery in children after exposureto desflurane was faster than those patients receiving isoflurane;recovery from desflurane, but not isoflurane, was relativelyunaffected by the duration of anaesthesia.