摘要
目的通过评价右美托眯定局部用药对罗哌卡因臂丛神经阻滞半数有效浓度（EC50）的影响，探讨其局部用药的镇痛机制。方法前臂及手部择期手术患者52例，年龄18～50岁，体重50～80kg，ASA分级I或Ⅱ级，拟在超声引导下行腋路臂丛神经阻滞。采用随机数字表法，将其分为2组（n=26），对照组（C组）神经阻滞时仅用罗哌卡因；右美托咪定组（D组）神经阻滞时局部注射罗哌卡因和0．8μg／kg右美托眯定的混合液。以臂丛支配区痛觉消失为阻滞有效，局麻药容量30ml，采用序贯法确定罗哌卡因浓度：初始浓度为0．50％，相邻浓度比值为1．2，阻滞有效则下一例采用低一级浓度，阻滞无效则下一例采用高一级浓度。用Dixon．Massey法确定EC50及其95％可信区间。结果D组罗哌卡因EC50（95％可信区间）为0．32％（0．30％～0．33％），C组为0．44％（0．42％～0．46％）。D组罗哌卡因EC50低于C组（P〈0．05）。结论右美托咪定局部用药可降低罗哌卡因臂丛神经阻滞的EC50提示其具有局麻药样效应。
Objective To investigate effect of local application of dexmedetomidine on the medium effec- tive concentration （EC50） of ropivacaine for brachial plexus block and the mechanism of the analgesic effect in- duced by dexmedetomidine. Methods Fifty-two ASA Ⅰ or Ⅱ patients of both sexes, aged 18-50 yr, weighing 50-80 kg, scheduled for elective forearm or hand surgery, requiring ultrasound-guided axillary brachial plexus block, were randomly assigned into 2 groups （ n = 26 each） ： control group （group C） and dexmedetomidine group （group D）. Axillary brachial plexus block was performed using only ropivacaine in group C. In group D the mixture of ropivacaine and 0. 8 μg/kg dexmedetomidine was injected for the block. The effective block was defined as com- plete loss of pain sensation in the brachial plexus distribution. The volume of local anesthetics was 30 ml. The con- centration of .ropivacaine was determined by up-and-down technique. The initial concentration was 0.5 % and the ratio between the two successive concentrations was 1.2. If the block was effective, the next patient received a lower dose of ropivacaine, or if ineffective, a higher dose was given in the next patient. The EC50 and 95 % confi- dence interval of ropivacaine were determined using the Dixon-Massey method. Results The EC50 （95 % confi- dence interval） of ropivacaine was 0.32% （0.30%-0.33%） in group D and 0.44% （0.42%-0.46%） in group C. The EC50 of ropivacaine was significantly lower in group D than in group C （ P 〈 0.05 ）. Conclusion Local application of dexmedetomidine can decrease the EC50 of ropivacaine for brachial plexus block guided by ultra- sound, indicating that the mechanism of the analgesic effect induced by dexmedetomidine is related to the local an- esthetic-like effect.
出处
《中华麻醉学杂志》
CAS
CSCD
北大核心
2013年第3期328-330,共3页
Chinese Journal of Anesthesiology
