Pretreatment of Rocuronium Reduces the Frequency and Severity of Etomidate-induced Myoclonus

Study Objective: To investigate the effect of pretreatment with a low dose of rocuronium on the occurrence of etomidate-induced myoclonus.

Design: Prospective, randomized, double-blinded study.

Setting: Medical center in South Korea.

Patients: 110 ASA physical status I, II, and III patients scheduled for elective cardiac or pulmonary surgery with general anesthesia.

Interventions: All patients were randomized to pretreatment with a low dose of rocuronium (0.06 mg/kg; Group R) or placebo (saline; Group S), followed three minutes later by etomidate (0.3 mg/kg).

Measurements: Patients were monitored for myoclonic movements and pain on a scale of 0-3. Bispectral index (BIS) and electromyographic (EMG) activity were recorded continuously throughout the procedure.

Main Results: Frequency of myoclonus was significantly lower in Group R (25%) than in Group S (63%). In the latter group, there was no difference in the frequency of male (59%) and female (68%) patients experiencing myoclonus. In Group S, EMG activity and BIS were significantly increased in patients who experienced severe myoclonus, and BIS was well correlated with EMG activity.

Conclusions: Pretreatment with a small dose of rocuronium before induction of anesthesia with etomidate significantly reduced the frequency of myoclonus.