(1515) Ketamine as a Rescue Drug for Benzodiazepine-Resistant Status Epilepticus in the Prehospital Setting

Introduction: Basic science data, early clinical findings and various feasibility factors have provided rationales for using ketamine as a proposed rescue drug for benzodiazepine-resistant status epilepticus (SE) in the challenging prehospital environment. This report details the multi-year outcome experience of paramedics managing midazolam resistant SE following introduction of a ketamine rescue protocol.

Methods: A 7 year, population-based, observational study was conducted in a large, diversely populated U.S county (pop. ~1 million) to evaluate outcomes of patients receiving 9-1-1 emergency response for persistent SE resistant to up to 10 mg of midazolam and then were treated with intravenous, intra-osseous, intramuscular or intranasal (IV/IO/IM/IN) ketamine as a rescue drug. Adults/pubescent adolescents received 100 mg ketamine IV/IO/IM/IN and children 1 mg/kg IM/IN. Tracked outcomes included: 1) rapid/sustained termination of convulsions while under paramedics’ care; 2) corresponding evaluations in children/adolescents; 3) any concerning observations regarding need for assisted-ventilation/intubation/other active/invasive interventions post-ketamine; 4) any identifiable associations between outcomes and circumstances, demographics or medical history.

Results: Among 81 total cases, 57 involved adults (ages 18-86 years) receiving the SE midazolam/ketamine protocol. Ketamine fully terminated convulsions in every case (100%) without recurrence while under paramedics’ care. For approved reasons, paramedics administered ketamine directly (no midazolam) in 8 other adults and one child, also terminating convulsions in every case. Among 15 childhood/adolescent cases (ages 1-17), treated per protocol, ketamine terminated convulsions in 12, but only mitigated them in 4, two of whom received ketamine intra-nasally. In retrospective, one was also a likely case of post-anoxic posturing. For all 81 adults and children/adolescents, there were no clinically significant ketamine-attributable complications identified and, in particular, no need for additional active interventions.

Conclusions: Among adults with on-going out-of-hospital seizures resistant to significant dosings of midazolam, ketamine was consistently effective in terminating those convulsions. Near-similar results were achieved in children/adolescents.