静脉输注右美托咪定对罗哌卡因骶管阻滞半数有效浓度的影响

Effect of intravenous dexmedetomidine on median effective concentration of ropivacaine for caudal block

目的:骶管阻滞具有操作简单、损伤小、起效快和麻醉效果明确等特点,是儿童和成人接受下肢、泌尿系统或肛肠手术的常用麻醉方法。静脉输注右美托咪定(intravenous dexmedetomidine,IV-DEX)是区域麻醉过程中常用的镇静方法,显示了其对局麻药的协同作用。本研究的目的是验证IV-DEX是否会降低局麻药骶管阻滞的半数有效浓度(median effective concentration,EC50)。方法:纳入60例计划行择期痔切除术的患者,分为2组,静脉输注生理盐水组(intravenous-normal saline,IV-NS组)和IV-DEX组。IV-NS组和IV-DEX组分别在骶管阻滞前15 min静脉输注20 mL生理盐水和1μg/kg右美托咪定(生理盐水稀释至20 mL)。采用Dixon-Massey“上下”顺序分配法确定罗哌卡因骶管阻滞的EC50。记录患者术中生命体征,需要药物处理的低血压、心动过缓和术中其他不良反应发生情况。结果:IV-NS组罗哌卡因骶管阻滞的EC50为0.280%,IV-DEX组为0.233%(P<0.05)。与IV-NS组相比,IV-DEX组中罗哌卡因的EC50降低16.8%(P=0.000),具有统计学差异。2组间需要药物治疗的低血压、心动过缓和术中其他不良反应发生率无统计学差异。结论:IV-DEX可以降低罗哌卡因骶管阻滞的EC50,但IV-DEX可能导致低血压、心动过缓的发生率增加。因此,IV-DEX与局麻药协同作用的最佳剂量仍需要进一步探索。

Objective:Caudal block,characterized by simple operation,small injury,rapid onset and definite anesthetic effect,is a common anesthesia method for children and adults undergoing lower extremity,urinary system or anorectal surgery.Intravenous dexme⁃detomidine(IV-DEX)is a commonly used sedative method during regional anesthesia,but it also shows synergistic effect on local anes⁃thetics.This study aims to examine whether IV-DEX reduces the median effective concentration(EC50)of local anesthetics for caudal block.Methods:Sixty patients scheduled for elective hemorrhoidectomy were enrolled in the study and divided into intravenousnormal saline(IV-NS)group and IV-DEX group.In IV-NS group and IV-DEX group,20 mL saline and 1μg/kg dexmedetomidine(diluted to 20 mL)were intravenously infused 15 min before caudal block,respectively.The EC50 of ropivacaine for caudal block was determined by Dixon-Massey“up and down”sequential assignment method.Vital signs,hypotension,bradycardia,and other intraop⁃erative adverse events requiring medical treatment were recorded.Results:The EC50 of ropivacaine for caudal block in IV-NS group was 0.280%,and that in IV-DEX group was 0.233%(P<0.05).Compared with the IV-NS group,the EC50 of ropivacaine in the IVDEX group was decreased by 16.8%(P=0.000),and the difference was statistically significant.The incidence of hypotension,bradycar⁃dia,and other adverse events requiring medical treatment had no difference between the two groups.Conclusion:IV-DEX can reduce the EC50 of ropivacaine for caudal block,but it may lead to an increase in the incidence of hypotension and bradycardia.Therefore,the optimal synergistic dose of IV-DEX with local anesthetics still needs to be further explored.