右美托咪定对瓣膜置换术患者体外循环期间体循环阻力和氧代谢的影响

摘要

目的 观察右美托咪定对瓣膜置换术患者体外循环期间体循环阻力和全身组织氧代谢的影响.方法 40例择期行二尖瓣置换术的患者,年龄40~55岁,体重45~65 kg,身高155~170 cm,性别不限,ASA Ⅱ~Ⅲ级,NYHA分级Ⅱ~Ⅲ级.采用随机数字表法将患者分为2组(n=20):右美托咪定组(D组)和对照组(C组).麻醉诱导后体外循环前D组经10 min静脉输注右美托咪定1.0 μg/kg,继之以0.5 μg/(kg·h)的速度持续输注直至体外循环结束,C组输注等容量的生理盐水.分别于上下腔静脉阻断后即刻(T1)、主动脉阻断后即刻(T2)、低温稳定期即鼻咽温稳定在30℃时(T3)、主动脉开放,心脏复跳后(T4)、上下腔静脉开放前即刻(T5)记录平均动脉压(MAP)、心输出量(CO)及心脏指数(CI)(以灌注流量代替CO、以灌注指数代替CI),并计算体循环阻力(SVR);抽取T1~ T5各时点的桡动脉血样和混合静脉血样,进行动静脉血气分析并计算氧供(DO2)、氧耗(VO2) 及氧摄取率(ERO2),同时测定桡动脉血血红蛋白(Hb)和动脉血乳酸浓度(Lac).结果 与C组比较,D组患者在T1~T5时CO、CI、DO2升高,SVR、VO2、ERO2、Lac降低(P<0.05).结论 麻醉诱导后体外循环前静脉输注右美托咪定1.0 μg/kg,继之以0.5 μg/(kg·h)的速度持续输注至体外循环结束可降低体外循环期间患者的SVR,改善全身组织的氧代谢状况,对器官保护具有一定的积极作用.%Objective To evaluate the effects of dexmedetomidine on systemic vascular resistance (SVR) and oxygen metabolism in systemic tissue during cardiopulmonary bypass (CPB) in patients undergoing valve replacement surgery.Methods Forty patients undergoing mitral valve replacement surgery,aged 40-55 ys,weighting 45-65 kg,heighting 155-170 cm,with ASA physical status Ⅱ or Ⅲ (NYHA Ⅱor Ⅲ),were randomly divided into 2 groups (n=20 in each) using a random number table: dexmedetomidine group (group D) and control group (group C).In group D,dexmedetomidine 1.0 μg/kg was infused intravenously for 10 min after induction of anesthesia before CPB,followed by continuous infusion of dexmedetomidine at 0.5 μg/(kg·h) until the end of the CPB,while in group C the equal volume of normal saline was given instead.Mean arterial pressure (MAP),cardiac output (CO,perfusion flow instead),cardiac index (CI,perfusion index instead) were measured and SVR was calculated accordingly immediately after the superior and inferior vena cava were blocked (T1),after aortic occlusion (T2),when nasopharyngeal temperature was stable at 30℃ (T3),when the aorta was opened,the heart was beating (T4),before the superior and inferior vena cava were opened (T5).At T1-T5,blood samples were collected from the radial artery and intravenous end of oxygenator for blood gas analysis,simultaneously Hb and lactate (Lac) concentration of arterial blood were measured.Oxygen delivery (DO2),oxygen consumption (VO2) and oxygen extraction ratio (ERO2) were calculated accordingly.Results Compared with group C,CO,CI and DO2 were significantly increased,SVR,VO2,ERO2 and the concentration of Lac were decreased at T1-T5 in group D.Conclusion Dexmedetomidine (1.0 μg/kg infused intravenously after induction of anesthesia before CPB,followed by infusion at a rate of 0.5 μg/(kg·h) until the end of CPB) can reduce the SVR in patients,improve the oxygen metabolism of systemic tissues during CPB and provide the protection of organs to some extent.