Out-of-Hospital Ketamine: Indications for Use, Patient Outcomes, and Associated Mortality

Study objective: To describe out-of-hospital ketamine use, patient outcomes, and the potential contribution of ketamine to patient death. Methods: We retrospectively evaluated consecutive occurrences of out-of-hospital ketamine administration from January 1, 2019 to December 31, 2019 reported to the national ESO Data Collaborative (Austin, TX), a consortium of 1,322 emergency medical service agencies distributed throughout the United States. We descriptively assessed indications for ketamine administration, dosing, route, transport disposition, hypoxia, hypercapnia, and mortality. We reviewed cases involving patient death to determine whether ketamine could be excluded as a potential contributing factor. Results: Indications for out-of-hospital ketamine administrations in our 11,291 patients were trauma/pain (49%; n=5,575), altered mental status/behavioral indications (34%; n=3,795), cardiovascular/pulmonary indications (13%; n=1,454), seizure (2%; n=248), and other (2%; n=219). The highest median dose was for altered mental status/behavioral indications at 3.7 mg/kg (interquartile range, 2.2 to 4.4 mg/kg). Over 99% of patients (n=11,274) were transported to a hospital. Following ketamine administration, hypoxia and hypercapnia were documented in 8.4% (n=897) and 17.2% (n=1,311) of patients, respectively. Eight on-scene and 120 in-hospital deaths were reviewed. Ketamine could not be excluded as a contributing factor in 2 on-scene deaths, representing 0.02% (95% confidence interval 0.00% to 0.07%) of those who received out-of-hospital ketamine. Among those with in hospital data, ketamine could not be excluded as a contributing factor in 6 deaths (0.3%; 95% confidence interval 0.1% to 0.7%). Conclusion: In this large sample, out-of-hospital ketamine was administered for a variety of indications. Patient mortality was rare. Ketamine could not be ruled out as a contributing factor in 8 deaths, representing 0.07% of those who received ketamine.