The Reduction in Minimum Alveolar Concentration for Tracheal Extubation After Clonidine Premedication in Children

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Abstract
The effects of clonidine on minimum alveolar concentration for tracheal extubation (MAC-ex) have not been elucidated. Clonidine may lead to prolonged emergence from anesthesia. We investigated the effects of oral clonidine premedication on MAC-ex and examined the emergence properties of sevoflurane in children. Sixty ASA physical status I pediatric patients, aged from 2 to 9 yr, were randomly divided into one of three groups and received placebo, clonidine 2 μg/kg, or clonidine 4 μg/kg (n = 20 each) orally, 100 min before the induction of anesthesia. The induction of anesthesia, tracheal intubation, and maintenance of anesthesia were performed with sevoflurane in air and oxygen. MAC-ex was defined according to the modification of Dixon’s up-and-down method, with 0.25% as a step size. In addition, in the Control and 4 μg/kg groups, the time from tracheal extubation to spontaneous eye opening (eye-opening time) and the time from tracheal extubation to leaving the operating room (awakening time) were recorded. MAC-ex for sevoflurane (mean ± sd) was 1.63% ± 0.13%, 1.04% ± 0.26%, and 0.66% ± 0.09% respectively in the Control group, 2 μg/kg group, and 4 μg/kg group. Significant differences were observed among the three groups. The eye-opening times were 5.7 ± 3.5 min in the Control group and 5.1 ± 1.0 min in the 4 μg/kg group. The awakening times were 9.7 ± 3.7 min in the Control group and 9.2 ± 3.8 min in the 4 μg/kg group. No significant differences were observed among the groups.