Pretreatment with butorphanol reduces myoclonus after etomidate

1.Etomidate is often used in the induction of general anesthesia with a very stable hemodynamic profile. Myoclonus is a common problem during induction of anesthesia with etomidate, which may be a problem in the non-fasting patient. It has been shown that the incidence of myoclonus is decreased with a variety of opioid agents. Butorphanol is a strong analgesic with both narcotic agonist and antagonistic properties. This study aims to determine the efficacy of butorphanol and fentanyl for prevention of etomidate-induced myoclonus. 2.One hundred-fifty ASA |-|| patients, undergoing elective surgery were randomly assigned into 3 groups of 50 each. Butorphanol group received butorphanol 2 mg, fentanyl group received fentanyl 100 μg, and placebo group received normal saline. Ninety seconds after pretreatment patients received etomidate 0.3 mg·kg-1. Assessment of myoclonus with IV etomidate was done by using a four-point scale: 0 = no myoclonus, 1 = mild myoclonus, 2 = moderate myoclonus, and 3 = severe myoclonus during a 60-second period after etomidate injection. 3.In the placebo group 41 (82%) patients had myoclonus after etomidate injection as compared to 12 (24%) and 2 (4%) in the fentanyl and butorphanol groups, respectively (p <0.001). 4.Butorphanol is an effective and safe drug to reduce the etomidate-induced myoclonus without significant effects.