摘要目的 确定分娩镇痛时硬膜外左旋布比卡因运动阻滞的半数有效浓度(EC50).方法 30例ASAI级初产妇,在第一产程宫颈开至2～3 cm时,L2,3硬膜外间隙穿刺,注射负荷量左旋布比卡因10ml,第1例产妇的左旋布比卡因浓度为0.5%,应用序贯法确定下一例产妇的药物浓度,相邻浓度比值为0.95.注药后30 min采用改良Bromage评分法评价下肢运动阻滞程度.结果 左旋布比卡因运动阻滞的EC50为0.562%,95%可信区间为0.542%～0.584%.结论 分娩镇痛时第一产程硬膜外左旋布比卡因(10 ml)运动阻滞的EC50为0.562%,95%可信区间为0.542%～0.584%.

abstractsObjective To determine the median effective concentration (EC50) of levobupivacaine for motor block in epidural labor analgesia.Methods Thirty ASA I nulliparous parturients with 2-3 cm cervical dilatation in the first stage of labor who requested epidural analgesia were enrolled in this study.Epidural catheter Was placed at L2,3 interspace and advanced for 3 cm cephalad in the epidural space.Each parturient received a bolus of 10 ml epidural levobupivacaine.The initial levobupivacaine concentration wag O.5%.Up-and-down sequential allocation was used to determine EC50.The ratio between adjacent concentration was O.95.Thirty minutes after epidural administration the degree of motor block of lower extremities was assessed and scored using modified Bromage scale.Results The motor block EC50 of epidural levobupivacaine was 0.562% and the 95% confidence interval was 0.542%-0.584%.Conclusion The EC50 of epidural levobupivacaine(10 m1)in the first stage of labor is 0.562% with 95% confidenee imerval between 0.542%-0.584%.