The effect of injection rate on etomidate-induced myoclonus / 대한마취과학회지

ABSTRACT

BACKGROUND: Etomidate frequently causes myoclonus. Since the myoclonus is caused by a transient disequilibrium due to etomidate exposure in the CNS, we hypothesized that a slow rate of injection of the drug may decrease the incidence of myoclonus. We conducted a prospective randomized study to compare the effect of two different types of the etomidate injection rate on the incidence and severity of myoclonus. METHODS: Fifty patients were randomly assigned to the fast-injection group (group F) or slow-injection group (group S) Group F patients received etomidate (0.3 mg/kg) over ten seconds. The same dose was administered over two minutes for group S patients. The response to the injection of etomidate was graded on a four-point scale in a blinded manner. The time to loss of consciousness (LOC) was also recorded. RESULTS: The incidence of myoclonus was significantly lower (P < 0.001) in group S patients; 84% and 28% in group F and group S patients, respectively. The myoclonus was also significantly less severe in group S patients (P < 0.001). The time to LOC was significantly longer in group S patients (106 +/- 22 sec) than that of group F patients (49 +/- 18 sec, P < 0.001). CONCLUSIONS: With same dose, a slower rate of injection resulted in a lower incidence of myoclonus and can effectively reduce myoclonus without the use of a pretreatment agent.