Ketamine to Prevent Endotracheal Intubation in Adults with Refractory Non-convulsive Status Epilepticus: A Case Series.

Abstract

Non-convulsive status epilepticus (NCSE) is defined as status epilepticus (SE) with no obvious motor phenomenon and is diagnosed based on electroencephalogram (EEG). Refractory SE (RSE) is the persistence of seizures despite treatment with an adequately dosed first-line and second-line agents. Although guidelines for convulsive RSE include third-line agents such as intravenous anesthetic drugs (midazolam, propofol, or barbiturates), the therapeutic approach to NCSE is not well outlined. Treatment with traditional anesthetics invariably includes endotracheal intubation, which is associated with significant adverse events. Comparatively, ketamine, a non-competitive N-methyl-D-aspartate receptor antagonist is not associated with significant cardiorespiratory depression and may help in avoiding intubation. In this case series, we describe our experience with the early use of intravenous ketamine as the first anesthetic agent in patients with refractory NCSE to avoid endotracheal intubation. We present a case series of nine patients managed in the Neurointensive Care Unit at a university-affiliated tertiary care hospital. The study was approved by the hospital and university institutional review boards and the requirement for informed consent was waived for retrospective analysis of existing data, per institutional policy. All cases of SE were identified from a prospective database, and a subsequent retrospective chart review identified all patients with a diagnosis of refractory NCSE in whom ketamine was used as the first anesthetic agent. The primary endpoint was the avoidance of endotracheal intubation while on ketamine infusion. The secondary endpoint was defined as cessation of both clinical and electrographic seizures recorded on continuous EEG within 24h of ketamine administration. A total of nine patients experiencing refractory NCSE were included in this case series, with a median age of 61 (range 26-72) years and seven patients were male. The primary endpoint, avoiding intubation, was achieved in five out of nine (55%)cases. Six patients experienced resolution of refractory NCSE with ketamine administration as the sole anesthetic agent. Four patients required endotracheal intubation and three patients had a failure of seizure cessation with ketamine. Hypersalivation and pneumonia were the most common ketamine associated adverse events. In non-intubated patients, no deaths occurred. One patient was discharged home, four to subacute rehabilitation, one to along term acute care hospital, and one patient to hospice. The use of ketamine as the primary anesthetic agent may be a reasonable option to avoid endotracheal intubation in a subset of patients with refractory NCSE. This study is limited by its small sample size, retrospective design, and reliance on information obtained from chartreview.