收肌管阻滞术罗哌卡因浓度与维持膝关节术后功能锻炼肌力的关系

Relationship of ropivacaine concentration with muscle strength of knee functional exercise after adductor canal block

目的确定膝关节手术患者术后收肌管阻滞联合静脉自控镇痛(patient-controlled intravenous analgesia,PCIA)时,维持膝关节术后功能锻炼下肢肌力的罗哌卡因半数有效浓度(median effective concentration,EC;)和95%有效浓度(95%effective concentration,EC;)。方法行膝关节手术的患者43例,ASA分级Ⅰ~Ⅲ级。患者术后均行收肌管阻滞联合PCIA,采用Dixon序贯法选择患者接受罗哌卡因的浓度,首例患者选用质量分数0.375%罗哌卡因,以0.031%为1个罗哌卡因浓度梯度,若患者术后4 h下肢肌力分级<3级,则下1例患者下调1个罗哌卡因浓度梯度;若下肢肌力分级≥3级,则下1例患者上调1个罗哌卡因浓度梯度,直至出现第9个转折点。采用Probit法计算EC;、EC;及其95%CI。比较患者不同时间点下肢肌力分级、静息和运动时视觉模拟疼痛评分(visual analogue scale,VAS)、PCIA泵注速度,观察患者术后恶心、呕吐等不良反应发生情况。结果维持膝关节手术患者术后功能锻炼肌力的罗哌卡因EC;浓度及其95%CI为0.340%(95%CI:0.307%~0.370%),EC;浓度及其95%CI为0.249%(95%CI:0.032%~0.290%)。患者术后12、24、48 h时,下肢肌力分级、静息和运动时VAS评分和PCIA泵注速度均高于术后4、8 h(P<0.05),膝关节活动度低于术前(P<0.05)。患者术后恶心、呕吐平均发生率为5.3%,无尿潴留、皮肤瘙痒等不良反应发生。结论膝关节手术患者术后收肌管阻滞联合PCIA时,维持膝关节术后功能锻炼肌力的罗哌卡因EC;为0.34%,EC;为0.249%;推荐采用质量分数0.249%罗哌卡因为主导的多模式镇痛用于膝关节手术患者术后镇痛。

Objective To calculate the median effective concentration(EC;)and 95%effective concentration(EC;)of ropivacaine on muscle strength of knee functional exercise after adductor canal block(ACB)plus patient-controlled intravenous analgesia(PCIA)in patients undergoing knee surgery.Methods Forty-three patients with ASA physical status 1 to 3 degree underwent knee surgery,and ACB by ropivacaine combined with PCIA after surgery.Dixon sequential method was used to determine the concentration of ropivacaine.The concentration of ropivacaine was 0.375%in the first patient,and decreased by one gradient(0.031%)if the lower limb muscle strength grade was under 3 in 4 h after surgery in the second patient,otherwise increased by one gradient if the lower limb muscle strength grade was 3 or higher till the ninth turning point.EC;,EC;and 95%CI were calculated by Probit method.The lower limb muscle grade,visual analogue scale(VAS)at resting and exercise,and pump velocity of PCIA were compared at different time points,and the adverse reactions as postoperative nausea and vomiting were observed.Results The EC;and its 95%CI of ropivacaine to maintain the muscle strength of functional exercise after knee surgery were 0.340%(95%CI:0.307%-0.370%),and the EC;and its 95%CI were 0.249%(95%CI:0.032%-0.290%).The muscle strength,VAS scores at resting and exercise and pump velocity of PCIA were significantly higher at 12,24 and 48 h than those at 4 and 8 h after surgery,respectively(P<0.05),and the knee activity was lower than that before surgery(P<0.05).The mean incidence of postoperative nausea and vomiting was 5.3%,and no uroschesis or pruritus occurred.Conclusions The EC50 of ropivacaine on muscle strength of knee functional exercise after ACB plus PCIA is 0.34%,and the ED95 is0.249%.A low concentration of 0.249%ropivacaine is recommended for postoperative analgesia after knee surgery.