序贯试验法测定罗哌卡因和布比卡因术后硬膜外镇痛的EC_(50)

Determination of EC_(50) of ropivacaine and bupivacaine for postoperative epidural analgesia by up-down sequential allocation

目的通过序贯试验法测定罗哌卡因和布比卡因术后硬膜外镇痛的半数有效浓度(EC50),比较两者用于术后硬膜外镇痛的相对效能.方法选择ASAⅠ～Ⅱ级择期妇科手术病人65例,随机分为罗哌卡因和布比卡因两组,分别用罗哌卡因和布比卡因20 ml术后硬膜外镇痛.硬膜外给药浓度按序贯增减法进行调整,镇痛效果以100mm视觉模拟评分法(VAS)进行评估,VAS≤10 mm为镇痛有效,VAS＞10 mm为镇痛无效.按Dixon方法计算罗哌卡因和布比卡因的EC50.结果罗哌卡因组EC50为0.098%,布比卡因组EC50为0.052%.结论序贯增减法简便、高效、结果可信,适用于罗哌卡因和布比卡因术后硬膜外镇痛EC50的测定;罗哌卡因用于妇科术后硬膜外镇痛的效能低于布比卡因.

Objective To determine the median effective concentration (EC 50 ) of ropivacaine and bupivacaine for postoperative epidural analgesia, and compare the efficacy of the 2 analgesics. Methods Sixty-five patients (ASAⅠtoⅡ) scheduled for elective gynaecological surgeries were randomly assigned into ropivacaine and bupivacaine groups to receive postoperative epidural analgesia with the indicated analgesics (20 ml). The concentration was determined by the response of a previous patient to a higher or lower concentration using double-blinded, up-down sequential allocation. The analgesic efficacy was assessed with 100 mm visual analog pain scores (VAS), and effectiveness was defined as having a VAS≤10 mm. Result EC 50 was determined by the formula of Dixon and Massey, which was 0.098% and 0.058% for ropivacaine and bupivacaine respectively. Conclusion Up-down sequential allocation is a simple, efficient and reliable method for EC 50 determination of ropivacaine and bupivacaine, and the former has a lower efficacy during postoperative epidural analgesia.