Halfves the EC_(50) for remifentanil for tracheal induction in children during target-controlled infusion of propofol

Objective To determine the effective target effect-site concentration(EC) of remifentanil for intubation without muscle relaxants in children in 50% of patients(EC50) during a target-controlled infusion(TCI) of propofol at 6 μg/ml.Methods Twenty-eight ASA Ⅰ patients aged(6.6±1.0) years old undergoing elective plastic surgery were enrolled in the study.Propofol was administered by TCI at a target EC of 6 μg/ml followed by remifentanil given by TCI at EC of 4 ng/ml.After the equilibration between plasma and effect-site concentration,tracheal intubation manipulated.Using Dixon's up-and-down method,EC50 of remifentanil was determined by the response of the previous patients,by increments or decrements of 0.2 ng/ml.Results The EC50 of remifentanil was 4.67 ng/ml.The 95% confidence interval was 4.52-4.87 ng/ml.Conclusion The EC50 of remifentanil for tracheal intubation without muscle relaxant in children was 4.67 ng/ml during a TCI of propofol at 6 μg/ml.