蛛网膜下腔阻滞下膝关节镜半月板切除术罗哌卡因的半数有效剂量

Minimum effective local anesthetic dose of intrathecal ropivacaine for arthroscopic meniscectomy

目的：探索蛛网膜下腔阻滞下膝关节镜半月板切除术罗哌卡因的半数有效剂量（ED50）。方法蛛网膜下腔阻滞下膝关节镜半月板切除术患者25例，以序惯法研究罗哌卡因的 ED50，有效标准为：蛛网膜下腔阻滞后20 min ，感觉阻滞平面至少达到 T12水平；运动阻滞达到Bromage Scale评分大于或等于2分；蛛网膜下腔阻滞后至少1 h硬膜外不追加局部麻醉药物。首次剂量为10 mg ，根据上一个患者有效与无效结果减少或增加1 mg剂量。结果蛛网膜下腔阻滞下膝关节镜半月板切除术罗哌卡因的 ED50为12．24 mg （95％ C I：12．09～12．39）。结论蛛网膜下腔阻滞下膝关节镜半月板切除术罗哌卡因的应用剂量最好大于12．24 mg ，但麻醉效果可能还与局部麻醉药物的比重和患者因素（身高、体质量、年龄）有关。

Objective To determine the minimum effective local anesthetic dose （ED50 ） of spinal ropivacaine for arthroscopic meniscecto-my .Methods Twenty-five patients undergoing arthroscopic meniscectomy under combined spinal-epidural anesthesia received intrathecal ropivacaine .ED50 of ropivacaine was determined by the sequence method .The effective criteria were as follows ：the level of sensory block reaching at least T12 within 20 min after injection of the local anesthetic ;the motion block reaching the Bromage Scale score ≥2 within 20 min after injection of the local anesthetic ;no supplemental epidural anesthetic at least 1 h after injection of the local anesthetic .The initial dose was 15mg and according to the effective or ineffective results in previous patient ,a dose of ropivacaine 1 mg was decreased or increased . Results ED50 of ropivacaine for the arthroscopic meniscectomy was 12 .24 mg（95% CI 12 .09-12 .39） .Conclusion The dose of ropiva-caine more than 12 .24 mg for arthroscopic meniscectomy is the best .But the anesthetic effect may be related with the specific gravity of the local anesthetic and the patients′factors（height ,weight ,age） .