comparison of the effects of low-dose midazolam, magnesium sulfate, remifentanil and low-dose etomidate on prevention of etomidate-induced myoclonus in orthopedic surgeries

conclusions intravenous etomidate 0.03 mg/kg prior to induction can effectively reduce the incidence and severity of myoclonus linked to etomidate. results the incidence and intensity of myoclonus were significantly lower in the low-dose etomidate group. the incidence rates of myoclonus were 51 (71.85%), 61 (85.9%), 30 (42.3%) and 41 (57.7%), and the percentages of patients who experienced grade iii of myoclonus were 30 (58.8%), 32 (52.5%), 9 (30%) and 14 (34.1%) in the midazolam, magnesium sulfate, etomidate and remifentanil groups, respectively. the incidence and intensity of myoclonus were significantly lower in the low-dose etomidate group (p = 0.0001). no notable adverse effect was detected in our patients during the study period. objectives the present study was designed to compare the effectiveness of low- dose midazolam, magnesium sulfate, remifentanil and low-dose etomidate to suppress etomidate-induced myoclonus in orthopedic surgery. patients and methods a double-blind clinical trial study was conducted in an academic hospital from september 2014 to august 2015. two hundred and eighty-four eligible patients, american society of anesthesiologists class i - ii, scheduled for elective orthopedic surgery were randomly allocated into four equal groups (n = 71). they received premedication with intravenous low-dose midazolam 0.015 mg/kg, magnesium sulfate 30 mg/kg, remifentanil 1 μg/kg and low-dose etomidate 0.03 mg/kg two minutes before induction of anesthesia with 0.3 mg/kg intravenous etomidate. then the incidence and intensity of myoclonus were evaluated on a scale of 0 - 3; 0 = no myoclonus; 1 = mild (movement at wrist); 2 = moderate (movement at arm only, elbow or shoulder); and 3 = severe, generalized response or movement in more than one extremity, within ninety seconds. any adverse effect due to these premedication agents was recorded. background etomidate is a potent hypnotic agent with several desirable advantages such as providing a stable cardiovascular profile with minimal respiratory adverse effects and better hemodynamic stability compared with other induction agents. this drug is associated, however, with myoclonic movements which is characterized by a sudden, brief muscle contractions as a disturbing side-effect.