Evaluation of the Use of Ketamine in Prehospital Seizure Management: A Retrospective Review of the ESO Database.

Benzodiazepines fail to stop seizures in 30% to 40% of cases, a condition called benzodiazepine-refractory status epilepticus (BRSE). Ketamine is a potential treatment, but its use by emergency medical services (EMS) is poorly documented. A retrospective review of 99,576 EMS encounters for seizures from 2018 to 2021 found that ketamine was administered in 2.54% of cases. In 1,283 encounters without an airway procedure, 48% received ketamine alone and 52% received it with another antiseizure medication, most often midazolam. Ketamine use without an airway procedure rose from 0.90% to 1.45% over the study period, a 62% increase. Most administrations occurred in adult patients in the southern United States and urban areas. The growth in ketamine use supports prospective research into its value for prehospital seizure management.

Study at a glance

Abstract

Benzodiazepines are the primary antiseizure medication used by Emergency Medical Services (EMS) for seizures. Available literature in the United States and internationally shows 30% to 40% of seizures do not terminate with benzodiazepines called benzodiazepine refractory status epilepticus (BRSE). Ketamine is a potential treatment for BRSE due to its unique pharmacology. However, its application in the prehospital setting is mostly documented in case reports. Little is known about its use by EMS professionals for seizure management, whether as initial treatment or for BRSE, creating an opportunity to describe its current use and inform future research. We performed a retrospective review of 9-1-1 EMS encounters with a primary or secondary impression of seizure using the ESO Data Collaborative from 2018 to 2021. We isolated encounters during which ketamine was administered. We excluded medication administrations prior to EMS arrival and encounters without medication administration. Subgroup analysis was performed to control for airway procedure as an indication for ketamine administration. We also evaluated for co-administration with other antiseizure medications, dose and route of administration, and response to treatment. We identified 99,576 encounters that met inclusion. There were 2,531/99,576 (2.54%) encounters with ketamine administration and 50.7% (1,283/2,531) received ketamine without an airway procedure. There were 616 cases (48%, 616/1,283) where ketamine was given without another antiseizure medication (ASM) and without any airway procedure. The remaining 667 (52%) cases received ketamine with at least one other ASM, most commonly midazolam (89%, 593/667). Adjusted for the growth in the ESO dataset, ketamine use by EMS professionals during encounters for seizures without an airway procedure increased from 0.90% (139/15,375) to 1.45% (416/28,651) an increase of 62% over the study period. In this retrospective review of the ESO Data Collaborative, ketamine administration for seizure encounters without an airway procedure increased over the study period, both as a single agent and with another ASM. Most ketamine administrations were for adult patients in the south and in urban areas. The frequency of BRSE, the need for effective treatment, and the growth in ketamine use warrant prospective prehospital research to evaluate the value of ketamine in prehospital seizure management.