Butorphanol Pre-treatment Prevents Myoclonus Induced By Etomidate:a Randomised, Double-blind, Controlled Clinical Trial

QUESTIONS UNDER STUDY:Myoclonic movements are common problems during induction of anaesthesia with etomidate. The myoclonus occurring after etomidate administration may represent a form of seizure. Agonistic modulation of the κ opiate receptor may reduce seizures, and butorphanol acts in such a manner. The aim of this randomised, double-blind, placebo-controlled clinical trial was to test our hypothesis that pre-treatment with butorphanol might reduce the incidence and severity of myoclonus induced by etomidate.METHODS:Patients （108） with American Society of Anaesthesiologists physical status I or II were randomly assigned to one of two groups to receive either 0.015 mg/kg of butorphanol （n= 54） or saline （n= 54） intravenously. At two minutes after infusion of butorphanol or saline,0.3 mg/kg etomidate was given. The occurrence and severity （observational score of 0-3） of myoclonus was assessed during 2 minutes after administration of etomidate. For each patient, blood pressure （BP）, saturation of peripheral oxygen （SpO2）, and heart rate （HR） were measured.RESULTS:The incidence of myoclonus was significantly lower in Group Butorphanol than in Group Saline （13.0% vs 79.6%; RR= 0.163,95%CI: 0.081-0.329;χ2= 48.265,p<0.0001）. The severity levels of myoclonic movement were also significantly lower in Group Butorphanol than in Group Saline （p<0.0001）. Throughout the procedure, changes of BP, SpO2, and HR did not differ between the groups. There were no problems with bradycardia or hypotension.CONCLUSIONS:Infusion of 0.015 mg/kg butorphanol 2 minutes before etomidate administration is effective for suppressing myoclonus induced by etomidate during induction of general anaesthesia.Objective The aim of this prospective, randomized, double-blind controlled clinical trial was to evaluate the effects of pretreatment with dezocine on the incidence and severity of etomidate-induced myoclonus.Methods 108 ASA physical status I or II patients were randomly assigned to one of two groups to receive either 0.1mg·kg^-1 of dezocine（n = 54; Group D） or saline（n =54; Group S）. One minutes after infiision of study drugs,etomidate 0.3mg·kg^-1 was given. The occurrence and severity（observational score of 0-3） of myoclonus was assessed during two minutes after administration of etomidate, Non-invasive blood pressure（BP）, SpO₂ and HR were measured during the study period.Results The incidence and the intensity of myoclonus was significantly lower in the dezocine group（0%） than in the control group（75.9%）（P<0.001）. The cardiovascular profile throughout the procedure was stable in both groups. Mo case had a problem with bradycardia or hypotension.Conclusions In our study, i.v. infUsion of 0.1mg·kg^-1 dezocine 1 min before etomidate administration is demonstrated to be an effective method for suppressing etomidate-induced myoclonic movements during general anesthesia induction.