Department of Anaesthesia and Intensive Care, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
Anaesthesia. 2011 Sep;66(9):808-11. doi: 10.1111/j.1365-2044.2011.06813.x. Epub 2011 Jul 19.
Previous estimates for the end-tidal concentration of desflurane that allows removal of the laryngeal mask airway in 50% of anaesthetised adults (ED50) have ranged from 2.1% to 5.3%. To assess which value is correct, we studied 32 female patients (aged 30-50 years) undergoing intracavity caesium implants for cervical carcinoma under general anaesthesia. Anaesthesia was induced with propofol 2-3 mg.kg(-1) and maintained with desflurane in a 50% nitrous oxide-oxygen mixture. At the end of surgery, a predetermined target end-tidal desflurane concentration (starting at 4%) was maintained for 10 min using Dixon's up-down method and the laryngeal mask airway was removed. The target end-tidal concentration in the next patient was increased or decreased by 0.5% depending upon the response of the previous patient. Removal of the laryngeal mask airway without coughing, clenching, biting, movement or any adverse airway event during or within 1 min after removal was considered to be successful. We found that the laryngeal mask airway can be successfully removed in 50% (ED50) and 95% (ED95) of the anaesthetised adults at end-tidal desflurane concentrations of 2.4% (95% CI 1.3-2.9) and 3.8% (3.1-9.6), respectively.
先前对于 50%全身麻醉成年人可移除喉罩的呼气末七氟醚浓度（ED50）的估计值范围为 2.1%至 5.3%。为了评估哪个值是正确的，我们研究了 32 名接受腔内铯植入治疗宫颈癌的女性患者（年龄 30-50 岁）。麻醉诱导用丙泊酚 2-3mg/kg，并用 50%氧化亚氮-氧气混合物中的七氟醚维持。手术结束时，采用 Dixon 的上下法维持预定的呼气末七氟醚浓度（起始浓度为 4%）达 10 分钟，并移除喉罩。下一个患者的目标呼气末浓度根据前一个患者的反应增加或减少 0.5%。在移除期间或移除后 1 分钟内无咳嗽、紧握、咬牙、运动或任何气道不良事件发生，被认为是成功移除。我们发现，在呼气末七氟醚浓度分别为 2.4%（95%可信区间为 1.3-2.9）和 3.8%（3.1-9.6）时，喉罩可分别在 50%（ED50）和 95%（ED95）的全身麻醉成年人中成功移除。
