A descriptive study of myoclonus associated with etomidate procedural sedation in the ED

Myoclonus is a well-recognized side effect of etomidate when given in induction doses for rapid sequence intubation. Most of the data reported on myoclonus with emergency department (ED) sedation doses are reported as a secondary finding.

Our objective was to prospectively quantify the incidence and duration of myoclonus associated with the administration of etomidate in the lower doses given for procedural sedation in the ED.

This was a prospective descriptive study performed between September 2008 and September 2010 at an urban teaching hospital ED with approximately 50000 patient visits per year. Procedural sedation was performed at the discretion of the treating emergency physician, and adult patients receiving etomidate were eligible for enrollment. The occurrence and duration of myoclonus were observed and recorded. Any interference of myoclonus with the ability to complete the procedure was recorded, and adverse effects were identified.

Thirty-four eligible subjects were enrolled, and 36 separate sedation procedures were performed. The mean initial etomidate dose was 0.13 mg/kg (range, 0.077-0.20), and the mean total etomidate dose was 0.15 mg/kg (range, 0.077-0.29). Myoclonus was noted in 26 (72%) of 36 sedations. Mean time to onset of myoclonus was 50 seconds (range, 15-146), and the mean duration was 93 seconds (range, 03-557). Myoclonus interfered with the procedure in only 1 (3%) of 36 attempted procedures, and no procedure was unsuccessful because of myoclonus.

Myoclonus associated with sedation doses of etomidate was common but rarely interfered with the completion of a procedure.