摘要:目的:定量测定50 %小儿在喉罩表面涂抹丁卡因胶浆的情况下平稳拔除喉罩时呼气末七氟烷浓度。方法:25例择期行四肢及体表手术的患儿,高流量吸入七氟烷诱导并以七氟烷和氧化亚氮维持麻醉,不使用肌肉松弛剂及静脉麻醉药物,手术结束后停止吸入氧化亚氮,并维持设定的七氟烷浓度10min后拔除喉罩。根据Dixon序贯法确定喉罩拔除时的七氟烷浓度,每0.1 Vol%七氟烷为1个增减单位。患儿未出现咳嗽、牙关紧闭、体动、屏气及喉痉挛则认为拔除喉罩平稳。结果:50 %小儿平稳拔除喉罩时呼气末七氟烷浓度(EC50)为1.22 Vol%(95 %的置信区间分别为0.99 Vol%～1.49 Vol%)。结论:在喉罩表面涂抹丁卡因胶浆的情况下,3～8岁患儿喉罩满意拔除时呼气末七氟烷EC50值为1.22 Vol%。Abstract: Objective: To determine the concentration of sevoflurane where 50%( EC50 ) of the attempts to remove the laryngeal mask airway (LMA ) with the Teracainum Gel would be successful in children. Methods: Twentyfive nonpremedicated children, aged 38 years old, ASA physical status I, scheduled for extremities or peripherical surgery were enrolled in this study. General anesthesia was induced with sevoflurane and maintained with sevoflurane and nitrous oxide in oxygen. After the surgery, the target concentration was maintained for at least 10 min, and then the LMA was removed. Each target concentration was predetermined by the Dixon’s upanddown method (with 0.1 Vol% as a step size), starting at 1.20 Vol% concentration of sevoflurane. A removal accomplished without coughing, teeth clenching, gross purposeful movement, breath holding or laryngospasm, during or within 1 min after removal was considered to be successful. Results:The concentration of sevoflurane to achieve successful LMA removal in 50% of children was 1.22 Vol% (95%CL, 0.99 Vol%1.49 Vol%). Conclusion: The EC50 value of sevoflurane for LMA smooth extubation in children aged 38 years old with teracainum gel was 1.22 Vol%.