Fifty Percent Of Effective Concentration Of Sufentanil For Intubating Laryngeal Mask Airway Insertion In Obese Patients With Dexmedetomidine Sedation

Objective: To determine the fifty percent of effective concentration of sufentanin for Intubating Laryngeal Mask Airway insertion in obse patients during dexmedetomidine sedation with sequential method, in order to provide reference for clinical induction of anesthesia.Method: ASA physical status I or II obse patients (BMI≥25kg/m2 )undergoing elective surgical operation under general anesthesia were enrolled in this study. All the patient were fasting and premedicated with atropine 0.5mg half an hour before anaesthesia. All the patients were transfused 500ml Lactated Ringer's solution via the right elbow in half an hour before operation. The electrocardiogram,noninvasive blood pressure,pulse,blood oxygen saturation and BIS were monitored, given by oxygen mask(oxygen flow 3L/min). 5 min later received dexmedetomidine i.v. by a singlel 10-min infusion of 1.0μg/kg, and 1.0μg/kg/h followed till the BIS fell to 55~50. Then sufentanil was administered using target-controlled infusion with the Gepts model, and the Intubating Laryngeal Mask Airway was inserted through the awaked patient, when effective concentration achived the pre-setting concentration. Effective concentration of sufentanil was selected for each patient according to Sequential method. The ratio of two consecutive effective concentration was 1.1.The experiment started from effective concentration of sufentanil at 0.30ng/ml.The first enrolled patient was calculated from the one before who had positive response for laryngeal mask insertion. Patients were enrolled until six pairs positive-negative crossovers to obtain. The SBP,DBP,HR,SpO2 were recorded at the time the patient was quite 5min after entering operating room (T0),the effect compartement concentration of sufentanil came into ballence (T1),one minute (T2),three minutes (T3) and five minutes(T4) after laryngeal mask insertion was accomplished. Results: The EC50 of sufentanil was 0.23ng/ml. The 95% confidence interval was 0.21 ~ 0.25 ng/ml.Conclusion: The effective concentration of sufentanil at 0.23ng/ml can suppress responses to laryngeal mask insertion in 50% of obese patients with dexmedetomidine sedation when BIS was55~50.