Despotis G J, Summerfield A L, Joist J H, Goodnough L T, Santoro S A, Spitznagel E, Cox J L, Lappas D G
Department of Anesthesiology, Washington University School of Medicine, St. Louis, Mo 63110.
J Thorac Cardiovasc Surg. 1994 Dec;108(6):1076-82.
Previous reports suggest that activated clotting times do not correlate with heparin concentration during cardiopulmonary bypass. This study was designed to compare whole blood heparin concentration and activated clotting time measurements with laboratory-based plasma heparin concentration. Sixty-two patients having cardiac operations requiring cardiopulmonary bypass were enrolled in this study. The study was conducted in two phases. In phase I of this trial, blood specimens were obtained from 30 patients before heparin administration and after each of three heparin doses (20, 80, and 150 U/kg). In phase II, blood specimens were obtained from 32 patients before heparin administration and 10 minutes after each of the following: heparin administration (250 or 300 U/kg), initiation of cardiopulmonary bypass, achievement of hypothermia, initiation of rewarming, and immediately before discontinuation of bypass. Blood specimens were used to measure activated clotting time (kaolin and celite), whole blood heparin concentration, and anti-factor Xa plasma heparin concentration. In phase I, activated clotting time (celite: r = 0.91; kaolin: r = 0.93) and whole blood heparin concentration (r = 0.98) measurements correlated well with plasma heparin concentration. After initiation of cardiopulmonary bypass (phase II), weak correlations for activated clotting time measurements (celite: r = 0.34; kaolin: r = 0.59) and a strong correlation for whole blood heparin concentration (r = 0.95) were evident when compared with plasma heparin concentration. During bypass, activated clotting time measurements also inversely correlated with temperature (celite: r = -0.21; kaolin: r = -0.19) and hematocrit (celite: r = -0.26; kaolin: r = -0.21). A weak correlation between activated clotting time measurements and plasma heparin concentration is evident during the cardiopulmonary bypass period, probably because of the influence of both reduced hematocrit and temperature on the activated clotting time assay. In contrast, whole blood heparin measurements correlate well with plasma heparin concentration before and during bypass. Further studies are needed to determine whether maintaining heparin levels during cardiopulmonary bypass by monitoring heparin concentration is more effective in preventing consumptive activation of the hemostatic system, reducing bleeding, and minimizing the use of blood products after cardiopulmonary bypass when compared with a protocol based on activated clotting time.
以往的报告表明，在体外循环期间活化凝血时间与肝素浓度不相关。本研究旨在比较全血肝素浓度和活化凝血时间测量值与基于实验室的血浆肝素浓度。62例需要体外循环进行心脏手术的患者纳入本研究。该研究分两个阶段进行。在本试验的第一阶段，在30例患者肝素给药前以及给予三个肝素剂量（20、80和150 U/kg）中的每一个剂量后采集血标本。在第二阶段，在32例患者肝素给药前以及以下每个时间点后10分钟采集血标本：肝素给药（250或300 U/kg）、体外循环开始、体温降低达到时、复温开始时以及体外循环停止前即刻。血标本用于测量活化凝血时间（高岭土和硅藻土）、全血肝素浓度以及抗Xa因子血浆肝素浓度。在第一阶段，活化凝血时间（硅藻土：r = 0.91；高岭土：r = 0.93）和全血肝素浓度（r = 0.98）测量值与血浆肝素浓度相关性良好。在体外循环开始后（第二阶段），与血浆肝素浓度相比，活化凝血时间测量值的相关性较弱（硅藻土：r = 0.34；高岭土：r = 0.59），而全血肝素浓度的相关性较强（r = 0.95）。在体外循环期间，活化凝血时间测量值也与温度呈负相关（硅藻土：r = -0.21；高岭土：r = -0.19）以及与血细胞比容呈负相关（硅藻土：r = -0.26；高岭土：r = -0.21）。在体外循环期间，活化凝血时间测量值与血浆肝素浓度之间存在较弱的相关性，这可能是由于血细胞比容降低和温度对活化凝血时间测定均有影响。相比之下，全血肝素测量值在体外循环前及期间与血浆肝素浓度相关性良好。需要进一步研究以确定与基于活化凝血时间的方案相比，在体外循环期间通过监测肝素浓度维持肝素水平在预防止血系统的消耗性激活、减少出血以及使体外循环后血液制品使用最小化方面是否更有效。
