超声引导0.5%罗哌卡因股神经阻滞的半数有效剂量:单位股神经横截面积剂量

Median effective dose of 0.5% ropivacaine for ultrasound-guided femoral nerve block: dose per unit femoral nerve cross-sectional area

目的:确定超声引导0.5%罗哌卡因股神经阻滞时,按股神经横截面积用药的半数有效剂量(ED_(50))。方法:选择拟行髌骨骨折切开复位内固定术或髌骨骨折内固定取出术患者,ASA分级Ⅰ或Ⅱ级,BMI 20~30 kg/m^(2),年龄18~64岁,性别不限。超声引导下定位股神经,测量股神经横截面积,根据面积注射0.5%罗哌卡因,采用Dixon序贯法进行试验,起始剂量为0.22 ml/mm^(2),相邻剂量差值0.02 ml/mm^(2)。阻滞有效标准:神经阻滞30 min内膝关节前面皮肤、小腿内侧面和足背内侧缘皮肤均无痛觉和Brunnstrom运动功能评定法为1~3级。若以上神经分布区有1处存在痛觉即认为神经阻滞无效。出现7个有效和无效交替波终止研究。采用Probit法计算ED_(50)及其95%可信区间。结果:27例患者纳入研究,股神经横截面积(75±5)mm^(2)。超声引导下0.5%罗哌卡因股神经阻滞ED_(50)为0.106 ml/mm^(2),95%可信区间为0.069~0.125 ml/mm^(2)。结论:超声引导0.5%罗哌卡因股神经阻滞时,按股神经横截面积用药的ED_(50)为0.106 ml/mm^(2)。

Objective To determine the median effective dose(ED_(50))of 0.5%ropivacaine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block.Methods Patients of both sexes,aged 18-64 yr,of American Society of Anesthesiologists physical status I orⅡ,with body mass index of 20-30 kg/m^(2),scheduled for elective open reduction and internal fixation for patella fracture or removal of patella fracture by internal fixation,were enrolled in this study.Ultrasonic localization of femoral nerve was performed for measurement of the femoral nerve cross-sectional area,and 0.5%ropivacaine was injected based on the area.ED_(50) was determined by Dixon′s up-and-down sequential method.The initial dose was 0.22 ml/mm^(2),and the difference between the two successive doses was 0.02 ml/mm^(2).The effective block was defined as complete loss of pain sensation in the areas of anterior skin of knee joint,skin on the inner side of the calf and dorsal medial skin of the foot and the degree of motor block was in stages 1-3 assessed using Brunnstrom motor function within 30 min after nerve block.Nerve block was considered ineffective if pain occurred in any nerve distribution area mentioned above.The study was terminated if 7 effective and ineffective alternating waves occurred.ED_(50) and 95%confidence interval(CI)were calculated using Probit analysis.Results Twenty-seven patients were enrolled in the study with the femoral nerve cross-sectional area(75±5)mm^(2).ED_(50)(95%CI)of 0.5%ropivacaine for ultrasound-guided femoral nerve block was 0.106(0.069-0.125)ml/mm^(2).Conclusion ED_(50) of 0.5%ropivacaine based on femoral nerve cross-sectional area for ultrasound-guided femoral nerve block is 0.106 ml/mm^(2).