The impact of clonidine on sedation after adenotonsillectomy: a prospective audit.

AIMS: Clonidine may be used intraoperatively to decrease emergence delirium in children, but the drug's impact on postoperative sedation is poorly quantified. METHODS: A prospective audit of children (≤15 years) undergoing (adeno) tonsillectomy or adenoidectomy over a period of 4 months was carried out. All children received sevoflurane for induction and maintenance of anesthesia. The use of clonidine as an adjunct was left to the discretion of the anesthesiologist. Postoperative sedation was assessed using the University of Michigan Sedation Scale (UMSS) at 30 min intervals until discharge. Arousal was characterized using a zero asymptote model. The impact of clonidine dose on half-time to an awake state after anesthesia was investigated using nonlinear mixed effects models. Survival analysis was used to explore the effect of clonidine dose on discharge time. RESULTS: The mean age of children (n = 177) was 5.4 sd 3.3 years, range 0.8-15.0 years and weight was 23.8 SD 11.4 kg, range 10.0-76.4 kg. There were 73 children given clonidine 0.29-4.80 mcg·kg(-1) after induction. The half-time to emergence was 10.8 (95% CI 8.5, 13.2) min. Emergence half-time was increased to 15 min with clonidine 0.5 mcg·kg(-1), 20 min with clonidine 1.5 mcg·kg(-1), 25 min with clonidine 2 mcg·kg(-1) and 65 min with clonidine 4 mcg·kg(-1). Clonidine doses 0.5-3 mcg·kg(-1) did not affect hospital discharge time. CONCLUSIONS: Clonidine administered intraoperatively for (adeno) tonsillectomy or adenoidectomy prolonged emergence from anesthesia. Doses of 0.5-3 mcg·kg(-1) caused greater sedation in the postanesthesia care unit but did not impact on hospital discharge times.