不同体位对膝关节镜手术患者蛛网膜下腔阻滞罗哌卡因ED50的影响

目的研究不同体位对膝关节镜手术患者蛛网膜下腔阻滞罗哌卡因半数有效剂量(ED50)的影响。方法选取90例需要进行择期单侧膝关节镜手术的患者,年龄18~64岁,ASA分级为I或Ⅱ级,体质量指数(BMI)为18~24 kg/m^(2),根据不同的体位,这些患者被分为三组,分别是头高脚低0°组、10°组和20°组。试验采用序贯法,每组第1例患者均获得蛛网膜下腔注射0.75%罗哌卡因11.25 mg,接下来根据前1例患者蛛网膜下腔阻滞是否有效,决定下一位患者的剂量是否减少或增加0.75 mg。使用概率单位回归分析法,计算罗哌卡因在不同体位下的蛛网膜下腔阻滞ED50。结果三组的ED50分别为:0°组为11.625 mg(95%CI:11.259~11.991 mg);10°组为11.325 mg(95%CI:10.968~11.669 mg);20°组为9.373 mg(95%CI:8.963~9.765 mg)。与0°组比较,10°组和20°组运动阻滞恢复时间缩短,20°组ED50降低、最高感觉阻滞平面下降、运动阻滞起效时间延长(P<0.05);与10°组比较,20°组ED50降低、运动阻滞恢复时间缩短(P<0.05)。三组术中低血压和恶心呕吐发生率比较差异无统计学意义(P>0.05)。结论膝关节镜手术患者在保持头高脚低0°、10°、20°体位时,蛛网膜下腔阻滞罗哌卡因的ED50分别为11.625 mg、11.325 mg和9.373 mg。通过头高脚低20°的姿势可以降低蛛网膜下腔阻滞的罗哌卡因ED50。

Objective To investigate the effect of different body positions on the median effective dose(ED50)of ropivacaine for subarachnoid block in patients undergoing knee arthroscopic surgery.Methods 90 patients under elective unilateral knee arthroscopic surgery,age ranged from 18 to 64 years,of American Society of Anesthesiologists(ASA)physical status Ⅰ or Ⅱ,with body mass index(BMI)of 18~24 kg/m^(2),randomly divide into three groups according to different positions,the position was head high and foot low,and the angle was 0(group 0°),10(group 10°)and 20(group 20°).The initial dose of 0.75% ropivacaine was 11.25 mg.The effective dose was defined as reaching the T10 level within 10 minutes.Reduced or increased the dose of ropivacaine by 0.75 mg for the next patient using an up-down sequential allocation.The ED50 in different positions was calculated by probit analysis.Results The ED50 of 0.75%ropivacaine was 11.625 mg for the group 0°[95%CI:11.259 to 11.991 mg],11.325 mg for the group 10°(95%CI:10.968 to 11.669 mg)and 9.373 mg for the group 20°(95%CI:8.963 to 9.765 mg).Compared with the 0°group,the recovery time of motor block was shortened in the 10°group and the 20°group,and the ED50 was decreased,the highest sensory block plane was decreased,and the onset time of motor block was prolonged in the 20°group(P<0.05).Compared with the 10°group,the ED50 of the 20°group was decreased and the recovery time of motor block was shortened(P<0.05).There was no significant difference in the incidence of hypotension and nausea and vomiting(P>0.05).Conclusion The ED50 of ropivacaine for subarachnoid block is 11.625 mg,11.325 mg and 9.373 mg in patients with head high and foot low 0°,10°and 20°。The posture with 20°head high and foot low can reduce the ED50 of ropivacaine in subarachnoid block.