Polley L S, Columb M O, Lyons G, Nair S A
Department of Anesthesiology, University of Michigan Medical Center, Ann Arbor 48109-0048, USA.
Anesth Analg. 1996 Nov;83(5):987-90. doi: 10.1097/00000539-199611000-00015.
The minimum local analgesic concentration (MLAC) has been defined as the median effective local analgesic concentration (EC50) in a 20-mL volume in the first stage of labor. The aim of this study was to determine the local anesthetic sparing efficacy of epidural fentanyl by its effect on the MLAC of chloroprocaine. Fifty-six parturients, not exceeding 7 cm cervical dilation, who requested epidural analgesia were allocated to one of two groups in this double-blind, randomized, prospective study. After placing a lumbar epidural catheter, 20 mL of the solution being tested was given: chloroprocaine (n = 28) or chloroprocaine with fentanyl 3 micrograms/mL (60 micrograms) (n = 28). The concentration of chloroprocaine was determined by the response of the previous patient to a higher or lower concentration using up-down sequential allocation. Analgesic efficacy was assessed using 100-mm visual analog pain scores with 10 mm or less within 30 min defined as effective. The MLAC of chloroprocaine was reduced from 0.43% wt/vol to 0.26% wt/vol by fentanyl (P = 0.023). Thus, the addition of epidural fentanyl 3 micrograms/mL (60 micrograms resulted in a significant 40% reduction in the MLAC of chloroprocaine in the first stage of labor.
最低局部镇痛浓度（MLAC）被定义为第一产程20毫升容积中的中位有效局部镇痛浓度（EC50）。本研究的目的是通过其对氯普鲁卡因MLAC的影响来确定硬膜外给予芬太尼对局部麻醉药的节省效果。在这项双盲、随机、前瞻性研究中，将56例宫颈扩张不超过7厘米且要求硬膜外镇痛的产妇分配到两组中的一组。置入腰段硬膜外导管后，给予20毫升受试溶液：氯普鲁卡因（n = 28）或含3微克/毫升（60微克）芬太尼的氯普鲁卡因（n = 28）。氯普鲁卡因的浓度根据前一位患者对更高或更低浓度的反应采用序贯上下法确定。使用100毫米视觉模拟疼痛评分评估镇痛效果，30分钟内评分10毫米或更低定义为有效。芬太尼使氯普鲁卡因的MLAC从0.43%重量/体积降至0.26%重量/体积（P = 0.023）。因此，硬膜外给予3微克/毫升（60微克）芬太尼可使第一产程中氯普鲁卡因的MLAC显著降低40%。
