Lacassie Héctor J, Columb Malachy O, Lacassie Héctor P, Lantadilla Rodrigo A
Anesthesiology Department, Pontificia Universidad Católica de Chile, Marcoleta 367, 3rd Floor, Santiago, Chile.
Anesth Analg. 2002 Jul;95(1):204-8, table of contents. doi: 10.1097/00000539-200207000-00036.
Minimal local analgesic concentrations (MLAC) have been used to determine the epidural analgesic potencies of bupivacaine and ropivacaine. There are no reports of the motor blocking potencies of these drugs. We sought to determine the motor block MLAC of both drugs and their relative potency ratio. Sixty ASA physical status I and II parturients were randomized to one of two groups, during the first stage of labor. Each received a 20-mL bolus of epidural bupivacaine or ropivacaine. The first woman in each group received 0.35%. Up-down sequential allocation was used to determine subsequent concentrations at a testing interval of 0.025%. Effective motor block was defined as a Bromage score <4 within 30 min. The up-down sequences were analyzed by using the Dixon and Massey method and probit regression to quantify the motor block minimal local analgesic concentration. Two-sided P < 0.05 defined significance. The motor block minimal local analgesic concentration for bupivacaine was 0.326% (95% confidence interval [CI], 0.285-0.367) and for ropivacaine was 0.497% (95% CI, 0.431-0.563) (P = 0.0008). The ropivacaine/bupivacaine potency ratio was 0.66 (95% CI, 0.52-0.82). This is the first MLAC study to estimate the motor blocking potencies of bupivacaine and ropivacaine. Ropivacaine was significantly less potent for motor block, at 66% that of bupivacaine.
The results of this study demonstrate that epidural ropivacaine is less potent than epidural bupivacaine in producing motor blockade during labor. The motor block potency relation is similar to the sensory potency ratio for these two drugs.
最小局部镇痛浓度（MLAC）已被用于确定布比卡因和罗哌卡因的硬膜外镇痛效能。尚无关于这些药物运动阻滞效能的报道。我们试图确定这两种药物的运动阻滞MLAC及其相对效价比。60例美国麻醉医师协会（ASA）身体状况为Ⅰ级和Ⅱ级的产妇在分娩第一阶段被随机分为两组。每组均接受20毫升硬膜外布比卡因或罗哌卡因推注。每组的第一名女性接受0.35%的浓度。采用上下序贯分配法，以0.025%的测试间隔确定后续浓度。有效运动阻滞定义为30分钟内布罗玛杰（Bromage）评分<4分。采用狄克逊（Dixon）和梅西（Massey）方法以及概率回归分析上下序列，以量化运动阻滞最小局部镇痛浓度。双侧P<0.05为有统计学意义。布比卡因的运动阻滞最小局部镇痛浓度为0.326%（95%置信区间[CI]，0.285 - 0.367），罗哌卡因为0.497%（95%CI，0.431 - 0.563）（P = 0.0008）。罗哌卡因/布比卡因效价比为0.66（95%CI，0.52 - 0.82）。这是第一项估计布比卡因和罗哌卡因运动阻滞效能的MLAC研究。罗哌卡因的运动阻滞效能明显较低，为布比卡因的66%。
本研究结果表明，在分娩期间硬膜外使用罗哌卡因产生运动阻滞的效能低于硬膜外使用布比卡因。这两种药物的运动阻滞效能关系与感觉效能比相似。
