Abstract. Objective: The optimal dose of IM ketamine for ED procedural sedation in children is not known. The authors wished to quantify the doseresponse 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 Յ15 years of age given IM 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 Ϯ 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 Ϯ 0.44 mg/kg vs 3.77 Ϯ 0.49 mg/kg, p = 0.041), and a nonsignificant trend was noted toward uniformly adequate sedation with increasing dose (Յ91% at <4.00 mg/kg, 93% at 4.00 -4.49 mg/kg, and 100% at Ն4.50 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 Ն4.00 mg/kg of ketamine, and the study had power (␣ = 0.05,  = 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 IM 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. Key words: ketamine; child; sedation; dissociative state; dosing. ACADEMIC EMER- GENCY MEDICINE 1999; 6:21 -26 T HE DISSOCIATIVE agent ketamine is a safe and effective sedative to facilitate the performance of painful and/or emotionally disturbing ED procedures in children. 1 -8 Despite the fact that the majority of the published experience involves the IM route, the optimal dose for IM ketamine has not been previously established. An ideal dose for ketamine should be sufficiently high to reliably produce adequate sedation conditions while still minimizing the time to discharge and the incidence of adverse effects.We previously reported clinical data from a consecutive case series of 1,022 IM ketamine administrations.1 The protocol at the study institutions recommended a dose of 4 mg/kg. Despite this, the treating physicians frequently chose either higher or lower doses at their discretion, and the data set includes a wide range of initial dosing choices (0.48 to 9.09 mg/kg). We analyzed our 1,022-case experience to test the hypotheses that adequacies of sedation, times to discharge, and the incidences of adverse effects differed by ketamine dose administered. Based upon such results, we then hoped to identify an optimal dose.
METHODSStudy Design. This was a retrospective analysis of the database of a prospective case series. The study was approved by the ...