Martindale S J, Shayevitz J R, D'Errico C
Addenbrookes Hospital, Cambridge, England.
J Cardiothorac Vasc Anesth. 1996 Jun;10(4):458-63. doi: 10.1016/s1053-0770(05)80004-7.
To determine how the stage of surgery affects the relationship between activated clotting time (ACT) and heparin effect in children undergoing cardiac surgery using cardiopulmonary bypass (CPB) and to compare the results of ACT determinations made with two different coagulation timers using different clot detection technologies and activator compositions.
Prospective, paired observation.
Tertiary care children's hospital affiliated with an academic medical center.
Fifty-eight children scheduled for nonprimary cardiac surgery.
None.
ACTs were measured by two different commercially available automated coagulation timers (Hepcon Hemostasis Management System [HP] and the Hemochron model 801 [HM]) at four different time points over the course of cardiac surgery requiring CPB in patients ranging in age from 0.16 to 19 years. Simultaneous determinations of whole blood heparin concentration using heparin-protamine titrations were made as well. When the two methods of ACT determination were compared, baseline ACTs were not significantly different. HP ACT prolongation after heparin administration but before bypass was significantly less than HM ACT prolongation (median ACT range HM > or = 999 seconds; HP, 560 to 679; p = 0.006). Twenty-one percent of the HP ACTs and none of the HM ACTs fell below the 480 seconds required at this institution for the initiation of CPB (p = 0.008). Both instruments showed a significant further prolongation of ACT after initiation of bypass (median ACT range HP > or = 999 seconds; HM > or = 999; p < 0.001 for both), whereas the heparin concentration decreased significantly (before, 3.5 +/- 0.2 U/mL; after, 2.7 +/- 0.1; p < 0.001). After termination of CPB and heparin neutralization, no significant difference between the ACTs was found. However, four HP ACTs were > or = 999 seconds despite simultaneous HM baseline values and whole blood heparin concentrations of zero. Heparin concentration correlated with ACT prolongation using both the HM (Spearman p = 0.36; p = 0.02) and the HP (Spearman p = 0.57; p = 0.0025) instruments before, but not 10 minutes after, initiation of bypass.
In pediatric cardiac surgery, the relationship between ACT and heparin concentration changes depending on when during the surgery the ACT is measured. ACT prolongation in children anticoagulated for CPB correlates poorly with heparin concentrations during CPB. HP and HM ACT tests are not interchangeable. The HM ACT is a better indicator of heparin neutralization than the HP ACT. On the other hand, continued prolongation of the HP ACT after heparin neutralization may be related to risk of postoperative hemorrhagic complications. If devices from different manufactures are freely substituted for each other, clinical practice may be altered in an uncontrolled manner.
确定手术阶段如何影响接受体外循环（CPB）心脏手术患儿的活化凝血时间（ACT）与肝素效应之间的关系，并比较使用不同凝血检测技术和激活剂成分的两种不同凝血计时器进行ACT测定的结果。
前瞻性配对观察。
一所学术医疗中心附属的三级护理儿童医院。
58名计划进行非初次心脏手术的儿童。
无。
在年龄从0.16岁至19岁、需要CPB的心脏手术过程中的四个不同时间点，使用两种不同的市售自动凝血计时器（Hepcon止血管理系统[HP]和Hemochron 801型[HM]）测量ACT。同时还使用肝素-鱼精蛋白滴定法同步测定全血肝素浓度。比较两种ACT测定方法时，基线ACT无显著差异。肝素给药后但体外循环前，HP测定的ACT延长明显小于HM测定的ACT延长（ACT中位数范围HM≥999秒；HP为560至679秒；p = 0.006）。该机构启动CPB所需的ACT为480秒，21%的HP测定ACT低于此值，而HM测定ACT均未低于此值（p = 0.008）。两种仪器在体外循环开始后均显示ACT进一步显著延长（ACT中位数范围HP≥999秒；HM≥999秒；两者p均<0.001），而肝素浓度显著下降（体外循环前3.5±0.2 U/mL；体外循环后2.7±0.1 U/mL；p < 0.001）。体外循环结束及肝素中和后，ACT之间无显著差异。然而，尽管同时HM基线值和全血肝素浓度为零，但仍有4次HP测定ACT≥999秒。在体外循环开始前，使用HM（Spearman p = 0.36；p = 0.02）和HP（Spearman p = 0.57；p = 0.0025）仪器时，肝素浓度与ACT延长相关，但体外循环开始10分钟后则不相关。
在小儿心脏手术中，ACT与肝素浓度之间的关系取决于ACT在手术中的测量时间。接受CPB抗凝的儿童ACT延长与CPB期间肝素浓度相关性较差。HP和HM ACT检测不可互换。与HP ACT相比，HM ACT是肝素中和的更好指标。另一方面，肝素中和后HP ACT持续延长可能与术后出血并发症风险有关。如果随意相互替换不同厂家的设备，临床实践可能会以无法控制的方式改变。
