罗哌卡因锁骨下入路单点法臂丛阻滞的最低有效浓度

The minimum local anesthetic concentration of ropivacaine in patient receiving infraclavicular brachial plexus block

目的研究并确定罗哌卡因在锁骨下入路臂丛阻滞的最低有效浓度（mini mum local anestheticconcentration,MLAC）,该浓度可达到感觉与运动分离,有利于减少臂丛阻滞的局麻药毒性反应,亦有利于外科医师及时发现术中神经损伤、判断术后效果。方法选取40名年龄18-65岁、美国麻醉医师协会（ASA）Ⅰ-Ⅱ级、择期行上肢肘关节以下部位手术的患者,均在神经刺激器引导下行锁骨下入路臂丛阻滞。采用序贯法进行试验,以60 mL为总量,第1例患者的起始浓度为0.25%,浓度分级为0.01%。设定注药后45 min内患者感觉阻滞2级,运动阻滞3级或3级以上,术中无牵拉痛,不需要静脉辅助用药为有效。若上一例有效,则下一例采用低一级浓度;若无效,则下一例采用高一级浓度。采用概率单位回归法计算满足手术的半数有效浓度（half-effective concentration,EC50）及其95%可信区间（95%confidenceinterval,95%CI）。结果所有患者均顺利完成研究。罗哌卡因的EC50及其95%CI分别为0.176%和0.116%-0.212%。结论罗哌卡因应用于锁骨下入路臂丛阻滞的最低有效浓度为0.176%,此浓度可在临床上使患者产生感觉与运动分离效应。

Objective To study the minimum local anesthetic concentration（MLAC） of ropivacaine in patients receiving infraclavicular brachial plexus block,under which concentration the effective anaesthesia was obtained with minimal motor block without local anesthetic systemic toxicity and neurotoxicity.It is better for surgeon to find nerve injury during the operation and to evaluate the effect after the operation.Methods Forty patients scheduled for surgical procedures below elbow were enrolled.All patients who were distributed to ASA physical status class Ⅰ-Ⅱ and aged between 18 and 65 years old received an infraclavicular brachial plexus block by nerve stimulator.The total volume was 60 mL,and the concentration started at 0.25% with concentration gradient of 0.01%,depending on the response of the previous patient,using the technique of up-down sequential allocation.Half-effective concentration（EC50） and 95% confidence interval（95% CI） were obtained by probit analysis.Results The EC50 and 95% CI for ropivacaine was 0.176% and（0.116%-0.212%）.Conclusions The minimum local anesthetic concentration of ropivacaine in patient receiving infraclavicular brachial plexus block was 0.176%.The effective concentration of ropivacaine can provide effective anaesthesia with minimal motor block.