Median effective concentration of remifentanil by TCI inhibiting cardiovascular response to placement of operating laryngoscopy performed under propofol anesthesia administered by TCI / 中华麻醉学杂志

ABSTRACT

Objective To determine the median effective concentration(EC50) of remifentanil by TCI inhibiting the cardiovascular response to the placement of operating laryngoscope performed under propofol anesthesia administered by TCI.Methods Twenty ASA Ⅰ orⅡ patients,aged 20-51 yr,weighing 52-83 kg,undergoing extirpation of vocal cord polyps under general anesthesia with remifentanil-pmpofol administered by TCI.were enrolled in the study.The target plasma concentration (Cp) of propofol was set at 4μg/ml.Operating laryngoscope was placed at 3 min after tracheal intubation.HR and MAP were continuously monitored.When HR or MAP increased by 15%,the candiovascular response was defined as positive.The EC50 was determined by up-and-down technique.The initial Cp of remifentanil was set at 5 ng/ml and was increased/decreased by 20%in the next patient if the cardiovascular response was positive or negative.Results No chest wall stiffness and intraoperative awareness occurred in all the patients.The EC50 of remifentanil TCI inhibiting the cardiovascular response to the placement of operating laryngoscope was 3.50ng/ml with confidence interval(CI) between 3.47-3.60 ng/ml.Conclusion Thee EC50 of remifentanil TCI inhibiting cardiovascular response to the placement of operating laryngoscope is 3.50ng/ml with CI between 3.47-3.60ng/ml.