Pretreatment with Esketamine Reduces Etomidate-Induced Myoclonus During the Induction of Anesthesia: A Randomized Controlled Trial

Background: Myoclonus is a common problem during induction of anesthesia with etomidate. A variety of agents, including opioids and lidocaine, reduced the incidence of myoclonus. However, there is no reported literature evaluating the effect of esketamine pretreatment on etomidate-induced myoclonus. We investigated the influence of pretreatment with esketamine on the incidence of etomidate-induced myoclonus. Methods: This is a prospective, double-blind, and randomized controlled trial. One hundred patients aged 18-65 scheduled for elective surgery under general anesthesia (including urology surgery, gynaecology surgery, general surgery, and thoracic surgery) were randomly allocated into two groups, each consisting of 50 patients. Esketamine was pretreated with 0.1 mg/kg 60 s before the initiation of etomidate in Group ESK, while normal saline was administered as the placebo (Group C). During the first 1 minute after etomidate administration, myoclonus incidence and severity were assessed. In addition, we measured the hemodynamic changes and side effects of esketamine before administering etomidate. Results: In group ESK, 14 patients (28%) had myoclonus (degrees of myoclonus: mild 2, moderate 7, severe 5), and 32 patients (64%) in group C (mild 6, moderate 5, severe 21) (P< 0.001). In group ESK, myoclonus incidence and severity were significantly lower than in group C (P< 0.001). Conclusion: Esketamine 0.1mg/kg IV pretreatment significantly reduce the incidence and the severity of severe myoclonus of etomidate-induced myoclonus without significant adverse effects.