蛛网膜下腔注射罗哌卡因与布比卡因运动神经阻滞效力的比较

The potencies for motor block after intrathecal ropivacaine and bupivacaine

目的 比较蛛网膜下腔注射罗哌卡因与布比卡因的运动神经阻滞效力.方法 择期脊椎.硬膜外麻醉下拟行泌尿外科腔镜手术患者60例,年龄18～64岁,体重46～75 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者随机分为2组（n=30）：0.5%罗哌卡因组和0.5%布比卡因组.按照序贯法进行试验,阻滞有效,下一例患者采用低一级剂量,阻滞无效,下一例患者采用高一级剂量,初始剂量均为4 mg,剂量梯度1 mg,阻滞有效的标准：蛛网膜下腔给药后5或10 min时任一下肢的任一种运动神经阻滞评分〉0分.采用序贯法计算蛛网膜下腔注射罗哌卡因或布比卡因运动神经阻滞的半数有效剂量（ED50）及其95%置信区间.结果 患者蛛网膜下腔注射罗哌卡因和布比卡因运动神经阻滞的ED50及其95%置信区间分别为6.68（6.27～7.13）mg和4.07（3.56～4.47）mg,效力比为O.61.结论 患者蛛网膜下腔注射罗哌卡因运动神经阻滞效力低于布比卡因.

Objective To determine the median effective doae （ED50） for motor block after intrathecal ropivacaine and bupivacaine. Methods Sixty ASA Ⅰ or Ⅱ patients, aged 18-64, weighing 46-75 kg, undergoing elective urological surgery under combined spinal-epidural anesthesia, were randomized into 2 groups （ n = 30each） receiving intrathecal 0.5% ropivacaine and 0.5% bupivacaine respectively. The ED50 was determined by up-down sequential allocation. The initial dose was 4 mg. Each time the dose increased/decreased by 1 mg. Efficacy was determined by the occurrence of any motor block in either lower extremity （modified Bromage scale 〉 0）within 5 or 10 min after the spinal injection. Results The intrathecal ED50 for motor block was 6.68 mg for ropivacaine （95% confidence interval 6.27-7.13 mg） and 4.07 mg for bupivacaine （95% confidence interval 3.56-4.47mg） . The relative motor blocking potency ratio was ropivacaine/bupivacaine 0.61. Conclusion The potency of intrathecal ropivacaine is lower than that of bupivacaine for motor block.