Effect target plasma concentration of remifentanil on tracheal bucking response in 50% patients

Objective To determine the effect target plasma concentration of remifentanil on tracheal bucking response in 50% patients(Cp50).Methods Twenty-four patients undergoing elective surgery with nasal trachea intubation were enrolled in the study.Midazolam 60 μg/kg was given,5 min later remifentanil was administered by TCI,then 1% dicaine 3 ml were injected through cricothyroid membrane.Bucking response and intubation response were recorded.TCI remifentanil was given by up and down method,and ratio of two close plasma concentrations was 1.2.Results The Cp50 of remifentanil was 1.8 μg/L.The 95% confidence level was 1.5-2.2 μg/L.Conclusion The Cp50 of remifentanil for suppression of bucking response was 1.8 μg/L in patients(95% CI 1.5-2.2 μg/L).