摘要
Abstract
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.关键词
右美托咪定/体外循环/体循环阻力/氧代谢Key words
Dexmedetomidine/Cardiopulmonary bypass/Systemic vascular resistance/Oxygen metabolism
