title: Comparison of the Effects of Low-Dose Midazolam, Magnesium Sulfate, Remifentanil and Low-Dose Etomidate on Prevention of Etomidate-Induced Myoclonus in Orthopedic Surgeries.
abstract: 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.
  
  
  OBJECTIVE
  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.
  
  
  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.
  
  
  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.
  
  
  CONCLUSIONS
  Intravenous etomidate 0.03 mg/kg prior to induction can effectively reduce the incidence and severity of myoclonus linked to etomidate.
authors.affiliation: Anesthesiology Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Sedighinejad
authors.affiliation: Anesthesiology Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran.
authors.forename: Bahram
authors.initials: B
authors.lastname: Naderi Nabi
authors.affiliation: Anesthesiology Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Haghighi
authors.affiliation: Anesthesiology Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran.
authors.forename: Gelareh
authors.initials: G
authors.lastname: Biazar
authors.affiliation: Anesthesiology Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran.
authors.forename: Vali
authors.initials: V
authors.lastname: Imantalab
authors.affiliation: Anesthesiology Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran.
authors.forename: Siamak
authors.initials: S
authors.lastname: Rimaz
authors.affiliation: Anesthesiology Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Zaridoost
keywords: Etomidate; Magnesium Sulfate; Midazolam; Prevention, Myoclonus; Remifentanil