Inadvertent ketamine overdose in children: Clinical manifestations and outcome

Study objective: We sought to characterize the clinical manifestations, out come, and etiology of inadvertent ketamine overdose in the emergency depart ment. Methods: We investigated cases of inadvertent ketamine overdose in children seen in the ED solicited through electronic mail subscription lists or rep orted to the Institute for Safe Medication Practices. The clinical manifest ations, outcome, and reported cause for each case are described. Results: We identified 9 cases of inadvertent ketamine overdose in children treated in the ED. Patients received either 5 (n=3), 10 (n=5), or 100 (n=1 ) times the intended dose, either by the intramuscular (n=5) or intravenous (n=4) route. All 9 experienced prolonged sedation (3 to 24 hours). Four ex perienced brief respiratory depression shortly after administration, and as sisted ventilation was performed in 2. Two children without respiratory dif ficulty or hypoxemia were intubated by their physicians as a precaution. In 5 children, the dosing error was not discovered until late in the sedation , often when the child was not waking at the expected time. No adverse outc omes were noted, and all children were normal neurologically on discharge a nd longer-term follow-up if available. Conclusion: No adverse outcomes were noted in 9 healthy children treated in the ED who inadvertently received 5 to 100 times the intended dose of keta mine. Toxicity manifested as prolonged sedation in all 9 and brief respirat ory depression in 4. The margin of safety in ketamine overdose may be wide, although less common and more serious outcomes cannot be excluded by this small, self-reported sample.