Perineural Dexmedetomidine as an Adjuvant Reduces the Median Effective Concentration of Lidocaine for Obturator Nerve Blocking: A Double-Blinded Randomized Controlled Trial

Research suggests that the addition of dexmedetomidine to local anesthetics can prolong peripheral nerve blocks; however, it is not known whether dexmedetomidine can reduce the quantity of local anesthetic needed. We hypothesized that adding dexmedetomidine as an adjuvant to an obturator nerve block could reduce the median effective concentration of lidocaine. In this double-blinded randomized trial, 60 patients scheduled for elective transurethral resection of bladder tumors on the lateral wall were randomly divided into two groups: the control group (C group, n = 30) and the dexmedetomidine group (D group, n = 30). Two main branches of the obturator nerve (i.e., anterior and posterior) were identified using neural stimulation at the inguinal level, with only lidocaine used for the C group and 1 μg/kg dexmedetomidine combined with lidocaine used for the D group. The median effective concentration was determined by an up-and-down sequential trial. The ratio of two consecutive concentrations was 1.2. The median effective concentration (95% confidence interval) of lidocaine was 0.57% (0.54%-0.62%) in the C group and 0.29% (0.28%-0.38%) in the D group. The median effective concentration of lidocaine was significantly lower in the D group than in the C group (p Trial Registration: ClinicalTrials.gov NCT02066727

现有研究表明，在局部麻醉药（local anesthetics）中加入右美托咪定（dexmedetomidine）可延长外周神经阻滞（peripheral nerve block）的持续时长，但目前尚不清楚右美托咪定是否能够减少所需局部麻醉药的用量。本研究假设，将右美托咪定作为佐剂（adjuvant）应用于闭孔神经阻滞（obturator nerve block），可降低利多卡因（lidocaine）的中位有效浓度（median effective concentration）。本项双盲随机对照试验（double-blinded randomized trial）共纳入60例拟行择期经尿道膀胱侧壁肿瘤切除术的患者，按随机原则分为两组：对照组（C组，n=30）与右美托咪定组（D组，n=30）。研究人员通过腹股沟水平的神经刺激定位，识别闭孔神经的两大分支（前支与后支）；对照组仅使用利多卡因，右美托咪定组则按1μg/kg的剂量联合使用右美托咪定与利多卡因。中位有效浓度通过上下序贯试验（up-and-down sequential trial）法进行测定，相邻两组浓度的比值为1.2。对照组利多卡因的中位有效浓度（95%置信区间（confidence interval））为0.57%（0.54%~0.62%），右美托咪定组则为0.29%（0.28%~0.38%）。右美托咪定组利多卡因的中位有效浓度显著低于对照组（p）。试验注册：ClinicalTrials.gov NCT02066727