What is the optimal dose of intramuscular ketamine for pediatric sedation?

OBJECTIVE: The optimal dose of i.m. ketamine for ED procedural sedation in children is not known. The authors wished to quantify the dose-response of ketamine with respect to sedation adequacy, time to discharge, and adverse effects in order to identify an optimal dose. METHODS: The study was a consecutive case series of 1,022 children < or = 15 years of age given i.m. ketamine in the EDs of a university medical center and an affiliated county hospital over a nine-year period. Adequacy of sedation, time to discharge, and adverse effects were compared with dose administered. RESULTS: Doses in the sample averaged 3.96+/-0.69 mg/kg, with a range of 0.48 to 9.09 mg/kg. Children judged to be adequately sedated received higher doses compared with those inadequately sedated (3.94+/-0.44 mg/kg vs 3.77+/-0.49 mg/kg, p=0.041), and a nonsignificant trend was noted toward uniformly adequate sedation with increasing dose (< or =91% at <4.00 mg/kg, 93% at 4.00-4.49 mg/kg, and 100% at > or = 4.50 mg/kg). No significant difference or trend in time to discharge or adverse effects was noted between the children receiving <4.00 mg/kg and those receiving > or = 4.00 mg/kg of ketamine, and the study had power (alpha=0.05, beta=0.20) to detect a 9-minute difference in times to discharge, a 3.3% difference in rates of airway complications, a 5.6% difference in rates of emesis, and a 12.3% difference in rates of recovery agitation. CONCLUSION: Ketamine doses of 4 to 5 mg/kg i.m. produced adequate sedation in 93%-100% of children, suggesting that this dosing range may be optimal for ED procedural sedation. No difference in time to discharge or adverse effects was observed for lower or higher doses.