Pretreatment of rocuronium reduces the frequency and severity of etomidate-induced myoclonus

To investigate the effect of pretreatment with a low dose of rocuronium on the occurrence of etomidate-induced myoclonus. Prospective, randomized, double-blinded study. Medical center in South Korea. 110 ASA physical status I, II, and III patients scheduled for elective cardiac or pulmonary surgery with general anesthesia. 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). 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. 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. Pretreatment with a small dose of rocuronium before induction of anesthesia with etomidate significantly reduced the frequency of myoclonus.