Camorcia M, Capogna G, Columb M O
Department of Anesthesiology, Città di Roma Hospital, Roma, Italy.
Int J Obstet Anesth. 2008 Jul;17(3):223-7. doi: 10.1016/j.ijoa.2007.05.015. Epub 2008 May 22.
The up-down sequential allocation model has been adapted to investigate a variety of clinical and pharmacological issues in neuraxial anaesthesia including the estimation of relative potency ratios for analgesia and motor block of the most commonly used epidural and intrathecal local anaesthetics. The aim of this study was to establish the median effective doses (ED50) for motor block with intrathecal lidocaine and bupivacaine and to define the relative motor blocking potency ratio.
In this prospective, randomised, double blind, parallel group, up-down sequential allocation study, we enrolled 71 parturients undergoing elective caesarean section under combined spinal-epidural anaesthesia. The women received either intrathecal lidocaine 2% w/v or bupivacaine 0.5% w/v. The initial dose was 4 mg for bupivacaine and 12 mg for lidocaine. Subsequent doses were determined by the outcome in the previous parturient, according to the up-down sequential allocation technique. The end point was the occurrence of any motor block in either lower limb within 5 min.
The intrathecal ED50 for motor block was 13.7 mg for lidocaine (95% CI, 13.1 to 14.4) and 3.4 mg for bupivacaine (95% CI, 2.6 to 4.1) (P<0.0001) and the relative motor blocking potency ratio was 4.1 (95% CI 3.3 to 5.2).
Intrathecal bupivacaine was 4.1 times more potent than lidocaine for motor block.
上下序贯分配模型已被用于研究神经轴麻醉中的各种临床和药理学问题，包括估计最常用的硬膜外和鞘内局部麻醉药的镇痛和运动阻滞的相对效价比。本研究的目的是确定鞘内注射利多卡因和布比卡因产生运动阻滞的半数有效剂量（ED50），并确定相对运动阻滞效价比。
在这项前瞻性、随机、双盲、平行组、上下序贯分配研究中，我们纳入了71例在腰麻-硬膜外联合麻醉下接受择期剖宫产的产妇。这些女性接受鞘内注射2% w/v利多卡因或0.5% w/v布比卡因。布比卡因的初始剂量为4 mg，利多卡因为12 mg。后续剂量根据前一位产妇的结果，按照上下序贯分配技术确定。终点是5分钟内任一下肢出现任何运动阻滞。
鞘内注射利多卡因产生运动阻滞的ED50为13.7 mg（95% CI，13.1至14.4），布比卡因为3.4 mg（95% CI，2.6至4.1）（P<0.0001），相对运动阻滞效价比为4.1（95% CI 3.3至5.2）。
鞘内注射布比卡因产生运动阻滞的效力是利多卡因的4.1倍。
