目的 观察右美托咪定(dexmedetomidine,Dex)复合0.25%盐酸罗哌卡因硬膜外麻醉对膝关节镜手术患者镇痛、镇静的影响,同时明确盐酸罗哌卡因硬膜外麻醉时的最适Dex剂量.方法 择期单膝关节镜手术患者80例(ASAⅠ或Ⅱ级,年龄25~60岁),随机分为4组,D1组(Dex 0.125μg/kg)、D2组(Dex 0.25μg/kg)、D3组(Dex 0.5μg/kg)、D4组(Dex 1μg/kg),将不同剂量的Dex加入0.25%盐酸罗哌卡因共20mL,硬膜外腔一次性给药.患者进入手术室后进行心电、无创血压、血氧饱和度监测,开放静脉,进行硬膜外麻醉(L1~2向下置管).记录入室(T0)、给药后10min(T1)、手术开始切皮(T2)、进入关节腔(T3)、进入关节腔后15min(T4)、手术缝皮结束(T5)时等各个时间点的平均动脉压(mean artery pressure,MAP)、心率(heart rate,HR);并进行T2、T3、T4、T5时的镇痛、镇静评分;记录患者的血氧饱和度,观察手术开始和结束时的麻醉平面和运动神经阻滞情况,术后记录患者开始感觉疼痛的时间,服用止疼药、恶心呕吐及尿潴留情况,并进行统计学分析.结果 D1~D4各组在T1~T5时间的平均动脉压和心率与T0时点相比差异有统计学意义(P＜ 0.01);同样,D1~D4各组在T2~T5时间的MAP和HR与T1时间相比差异有统计学意义(P＜0.01).组间比较,在T2~T5手术时间,D2~D4组的平均动脉压较D1组明显降低(P＜0.05或P＜0.01);在手术开始切皮(T2)时间,D2~D4组患者的镇痛评分明显低于D1组(P＜0.01),在T3~T4时间点,D3组的镇痛评分明显低于D2组(P＜0.05或P＜0.01),术后24h随访,D3、D4组患者术后服用镇痛药的例数少于D1、D2组,差异无统计学意义(P＞0.05).各组患者术后镇痛持续时间比较,差异均无统计学意义(P＞0.05);在T2~T4时间点,D3、D4组的镇静评分明显高于D1组、D2组(P＜0.01);各个时间点,D4组的镇静评分明显高于D3组,差异有统计学意义(P＜0.01);手术开始与结束时,D4组患者能抬腿的发生率均低于D1~D3组(P＜0.05或P＜0.01);术后24h随访,D3组患者恶心呕吐的发生率(0%)小于D1、D2、D4组,D3组患者尿潴留的发生率与D1组相同,但低于D2、D4组.结论 Dex复合低浓度局麻药应用于椎管手术,可以有效增强局麻药的镇痛效果;相比之下,0.5μg/kg Dex与盐酸罗哌卡因用于椎管内麻醉,对患者血流动力学影响小,术中及术后镇痛镇静作用完善且不良反应少.%Objective To observe the effect of epidural dexmedetomidine(Dex) with 0.25% ropivacaine hydrochloride on analgesia and sedation in arthroscopic knee surgery patients, and to determine the optimal concentration of Dex when combined with local anaesthetics in lower limbs surgeries. Methods A total of eighty patients of both gender aged 25 -60 years, American society of anaesthesiologist (ASA) physical status Ⅰ and Ⅱ who underwent single arthroscopic knee surgery were enrolled into the present study. Patients were randomly divided into four groups: D1 group(Dex 0. 125μg/ kg) , D2 group ( Dex 0. 25 μg/kg) , D3 group ( Dex 0. 5 μg/kg) , D4 group ( Dex 1 μg/kg ) . Different doses of Dex were added to 20ml 0. 25% ropivacaine hydrochloride,and were administered epidurally (introduced at L1-2 interspace,inserted 3cm into the epidural space in a decurrent direction) in the four groups. On arrival in the operating room,blood pressure,pulse oximetry and electrocardiogram were monitored. Heart rate(HR) ,mean artery pressure ( MAP) were recorded before anesthesia ( T0 ) ,10 minutes after epidural anesthesia ( T1 ) ,at skin incision ( T2 ) , into the articular cavity (T3) ,15 minutes after into the articular cavity (T4 ) and at the end of operation ( T5 ) . Intraoperative pain scores and sedation were recorded at T2 - T5. Besides cardio-respiratory parameters, pulse oxygen saturation, various block characteristics were also observed which included sensory analgesic level and motor blockade at the beginning and end of the operation. Postoperatively,time to first pain and analgesic using,side effects,such as nausea,vomiting and uroschesis were recorded. Results MAP and HR decreased in every group at T1 - T5 than at T0 ( P < 0. 01 ) ,and decreased in every group at T2 - T5 than at T1(P<0.01) ,MAP in D2 - D4 groups were lower than D1 group at T2 -T5. At T2 ,pain scores in D2 - D4 groups were lower than D1 group(P <0. 01) . Pain scores in D3 group were lower than D2 group at T3, T4 ( P < 0. 05 or P < 0. 01 ) , but there were no significant differences between D3 and D4 group. Patients who needed analgesic were fewer in D3, D4 groups than other groups(P <0. 01) . Ramsay scores were significantly higher in D3 ,D4 group than D1 ,D2 group at every time(P <0. 01) and higher in D4 group than D3 group(P <0. 01) . At the beginning and at the end of operation, motor blockade was fewer in D4 group than D1 and D3 group ( P < 0. 05 or P < 0.01). Postoperatively, side effects in every group had no differences, but that were lower in D3 group than other groups. Conclusion Dexmedetomidine combined with low concentration of ropivacaine hydrochloride in patients undergoing single arthroscopic knee surgery has the advantage of increasing analgesia for epidural analgesia. Dexmedetomidine 0. 5μg/kg provides stable hemodynamic, prolonged postoperative analgesia, lower consumption of postoperative analgesic with less adverse events.
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