Ketamine use in the treatment of refractory status epilepticus

Refractory status epilepticus (RSE) occurs when status epilepticus (SE) fails to respond to appropriate therapy with typical antiepileptic drugs (AEDs). Animal studies have shown ketamine to be a highly efficacious agent in this setting, but very few case reports describe use of ketamine in human SE or RSE. We report a retrospective review of 11 patients who were treated for RSE with ketamine infusion in addition to other standard AEDs over a nine-year period. Data collection included age, gender, history of epilepsy, etiology of RSE, daily dose of ketamine, co-therapeutic agents, duration of seizures, treatment response, and disposition. RSE was successfully terminated in all 11 patients treated with ketamine. Dosing ranged from 0.45 mg/kg/h to 2.1 mg/kg/h based upon the preference of the treating clinician and response to therapy, with maximal daily doses ranging from 1392 mg to 4200 mg. Ketamine was the last AED used prior to resolution of RSE in 7/11 (64%) cases. In the remaining four cases, one other AED was added after ketamine infusion had begun. Time from ketamine initiation to seizure cessation ranged from 4 to 28 days (mean=9.8, SD=8.9). In 7/11 patients, RSE was resolved within one week of starting therapy. Administration of ketamine was uniformly associated with improvement in hemodynamic stability. Six of the seven patients (85%) who required vasopressors during early treatment for RSE were able to be weaned from vasopressors during ketamine infusion. No acute adverse effects were noted. These findings suggest that ketamine may be a safe and efficacious adjunctive agent in the treatment of RSE.