Objective: Varying rates of complications have been reported for prehospital sedation with ketamine, and the relationship to dosing has not been studied on a large scale. We evaluated the association between prehospital ketamine dosing and rates of intubations and other adverse events in patients with behavioral emergencies.
Methods: Using the 2018/2019 ESO public-use research datasets, we included all non-traumatic, adult behavioral and drug-related EMS encounters with ketamine administration. Based on consensus guidelines, we stratified patients into "above" and "at/below" the maximum dosing for sedation (2 mg/kg IV/IO or 5 mg/kg IM) using the highest single dose of ketamine given. We created propensity scores for matched subjects using 1:1 propensity score matching. Using logistic regression, we compared rates of intubation and other airway interventions, antipsychotic coadministration, improvement reported by EMS, hypoxia, hypotension, and cardiac arrest between the two groups.
Results: We included 2383 patients: 478 in the above and 1905 in the at/below dose group. Above-dose ketamine was associated with a higher rate of intubation or supraglottic airway placement (6.4% v 3.3%, OR 2.0, 95% CI 1.00-3.90). Other airway interventions were similar (40.0% v 40.0%, OR 1, 95% CI 0.80-1.30). The above-dose group also showed a higher rate of improvement noted by EMS clinicians (92.5% v 88.7%, OR 1.6, 95% CI 1.01-2.40). The rates of antipsychotic coadministration, hypoxia, hypotension, and cardiac arrest were similar between the cohorts.
Conclusions: Patients given ketamine doses above consensus recommendations for sedation appeared more likely to receive prehospital intubation but not more likely to experience other adverse events.