[Prevention of myoclonus after etomidate using a priming dose]

To investigate the influence of pretreatment with a low dose of etomidate (priming dose) on the incidence of etomidate-induced myoclonus.

Prospective randomized double-blind study.

Forty six patients ASA physical status I - II, scheduled for abdominal elective surgery, were allocated randomly to receive either pre-treatment 0.03 mg/kg of etomidate (priming group) or placebo (control group). Sixty-seconds after the pre-treatment was injected, anesthesia was induced with etomidate 0.3 mg/kg and 60 seconds later induction was completed with fentanyl (3 microg/kg) and vecuronium (0.1 mg/kg). The occurrence and intensity of myoclonus were graded clinically by a blinded observer as: 0=no myoclonus, 1=mild myoclonus, 2=moderate myoclonus and 3=severe myoclonus.

Fisher test exact for qualitative variable and Student t-test for quantitative variables.

Demographic data and the average dose of etomidate used during the induction were similar in the 2 groups (0.29+/-0.032 mg/kg in the priming group and 0.30+/-0.029 mg/kg in the control group). Twenty patients (87%) in the control group experienced myoclonic movements whereas only 6 patients (26%) in the control group had such movements (P<0,001).

Pretreatment with etomidate (0.03 mg/kg), given 60 seconds before induction of anesthesia, is effective at reducing etomidate-induced myoclonus, without related side-effect.