Polley L S, Columb M O, Naughton N N, Wagner D S, van de Ven C J
Department of Anesthesiology, Women's Hospital, University of Michigan Health System, Ann Arbor, USA.
Anesthesiology. 1999 Apr;90(4):944-50. doi: 10.1097/00000542-199904000-00003.
The minimum local analgesic concentration (MLAC) has been defined as the median effective local analgesic concentration in a 20-ml volume for epidural analgesia in the first stage of labor. The aim of this study was to assess the relative analgesic potencies of epidural bupivacaine and ropivacaine by determining their respective minimum local analgesic concentrations.
Seventy-three parturients at < or = 7 cm cervical dilation who requested epidural analgesia were allocated to one of two groups in this double-blinded, randomized, prospective study. After a lumbar epidural catheter was placed, 20 ml of the test solution was given, either ropivacaine (n = 34) or bupivacaine (n = 39). The concentration of local anesthetic was determined by the response of the previous patient in that group to a higher or lower concentration using up-down sequential allocation. Analgesic efficacy was assessed using 100-mm visual analog pain scores with < or = 10 mm within 30 min defined as effective. An effective result directed a 0.01% wt/vol decrement for the next patient. An ineffective result directed a 0.01% wt/vol increment.
The minimum local analgesic concentration of ropivacaine was 0.111% wt/vol (95% confidence interval, 0.100-0.122), and the minimum local analgesic concentration of bupivacaine was 0.067% wt/vol (95% confidence interval, 0.052-0.082). Ropivacaine was significantly less potent than bupivacaine, with a potency ratio of 0.6 (95% confidence interval, 0.49-0.74). No difference in motor effects was observed.
Ropivacaine was significantly less potent than bupivacaine for epidural analgesia in the first stage of labor.
最小局部镇痛浓度（MLAC）被定义为分娩第一产程硬膜外镇痛20毫升容量中的中位有效局部镇痛浓度。本研究的目的是通过确定各自的最小局部镇痛浓度来评估硬膜外布比卡因和罗哌卡因的相对镇痛效能。
在这项双盲、随机、前瞻性研究中，将73例宫颈扩张≤7厘米且要求硬膜外镇痛的产妇分配到两个组中的一组。放置腰段硬膜外导管后，给予20毫升测试溶液，要么是罗哌卡因（n = 34），要么是布比卡因（n = 39）。局部麻醉药的浓度根据该组前一位患者对更高或更低浓度的反应，采用序贯上下分配法来确定。使用100毫米视觉模拟疼痛评分评估镇痛效果，30分钟内≤10毫米定义为有效。有效结果则下一位患者的浓度降低0.01%（重量/体积）。无效结果则下一位患者的浓度增加0.01%（重量/体积）。
罗哌卡因的最小局部镇痛浓度为0.111%（重量/体积）（95%置信区间，0.100 - 0.122），布比卡因的最小局部镇痛浓度为0.067%（重量/体积）（95%置信区间，0.052 - 0.082）。罗哌卡因的效能明显低于布比卡因，效能比为0.6（95%置信区间，0.49 - 0.74）。未观察到运动效应的差异。
在分娩第一产程中，罗哌卡因用于硬膜外镇痛的效能明显低于布比卡因。
