The effect of fentanyl pretreatment on myoclonus during induction of anesthesia with etomidate in elderly patients

Background: Etomidate is frequently used as an induction agent in the elderly patients. This study was done to determine whether etomidate-based induction can provide hemodynamic stability and fentanyl decreases the incidence of myoclonus. Methods: Eighty ASA II or III patients older than 65 years were randomly allocated to four groups. Group 1 (n = 20) received etomidate 0.2 mg/kg after normal saline 3 ml, Group 2 (n = 20) received etomidate 0.25 mg/kg after normal saline 3 ml, Group 3 (n = 20) received fentanyl 2 ug/kg before the administration of etomidate 0.2 mg/kg, Group 4 (n = 20) received fentanyl 2 ug/kg before the administration of etomidate 0.25 mg/kg. The time interval from etomidate infusion to loss of eyelash reflex, to decrease bispectral index (BIS) 50, to intubation were recorded. We measured hemodynamic change, the BIS index, the incidence, duration and grade of myoclonus. Results: There were no significant differences in time interval, mean arterial pressure (MAP), BIS index between groups. MAP and HR were increased after intubation in all groups. The incidence of myoclonus were 25%, 30%, 0%, 15% respectively. There were no significant differences in incidence and duration of myoclonus between 4 groups, but group 3 had reduced incidence compared with group 1. Conclusions: Loss of consciousness and hemodynamic changes during induction with 0.2 mg/kg and 0.25 mg/kg of etomidate were appropriate. Pretreatment with fentanyl and small dose of etomidate decrease the incidence of myoclonus.