The Effect of Midazolam for Reducing Myoclonus after Etomidate

Background: Etomidate is a rapid acting sedative agent used for the induction of general anesthesia. One of the side effects of etomidate limiting its usage is myoclonus. This study was designed to determine whether a small dose of midazolam decreases the incidence of myoclonus after infusion of etomidate. Methods: Eighty ASA physical status 1 or 2, 16－60 year old patients undergoing elective surgery were randomly allocated into two groups. Group 1 (n = 40) received normal saline 0.04 ml/kg and group 2 (n = 40) received midazolam 0.04 mg/kg 3 minutes before the administration of etomidate 0.3 mg/kg. We measured and compared the incidence, severity, onset time and duration of myoclonus, and blood pressure and heart rate. Results: There were significant differences in the onset time and severity of myoclonus, but no significant differences in the incidence and duration of myoclonus. Systolic blood pressure was significantly higher in group 1 than group 2 at 3 minutes after pretreatment drug administration, immediatly after etomidate administration and 3 minutes after etomidate administration. Conclusions: An infusion of 0.04 mg/kg midazolam 3 minutes before etomidate decreases the severity of myoclonus and the onset of myoclonus.