Green T P, Isham-Schopf B, Steinhorn R H, Smith C, Irmiter R J
Department of Pediatrics, University of Minnesota, Minneapolis.
Crit Care Med. 1990 May;18(5):494-8. doi: 10.1097/00003246-199005000-00006.
Bleeding complications are the principal cause of morbidity and mortality in infants treated with extracorporeal membrane oxygenation (ECMO). The whole blood activated clotting time (ACT) test is used universally to monitor heparin therapy during this procedure. To enhance our understanding of this test and improve our management of anticoagulation, we studied the relationship between the ACT and blood heparin concentration in nine infants during ECMO. The activated clotting time correlated with the simultaneously determined heparin concentration (r = .55, p less than .001 for all patients samples; r = .92, p less than .001 for mean patients values). Within the range of values found in our patients, platelet count, fibrinogen, and fibrin degradation products did not affect the ACT-heparin concentration relationship. However, the interpretation of an individual ACT result was limited by its low precision: the mean difference of duplicate determinations was 9.2%, and the estimation of heparin concentration by a single ACT had a coefficient of variation of 32%. Two commercially available techniques using different activators gave results that differed numerically but correlated well with each other. Both provided similar precision in the estimation of heparin concentration. The ACT is a low cost, bedside test whose accuracy and precision allow the achievement of target heparin concentrations required in infants during ECMO. Multiple determinations, either in duplicate or serially, are needed to achieve satisfactory precision. These data will be useful in designing future studies to determine the optimal serum heparin concentration to provide adequate anticoagulation, but avoid bleeding complications.
出血并发症是接受体外膜肺氧合（ECMO）治疗的婴儿发病和死亡的主要原因。全血活化凝血时间（ACT）检测普遍用于在此过程中监测肝素治疗。为了加深我们对该检测的理解并改善我们的抗凝管理，我们研究了9例接受ECMO治疗的婴儿的ACT与血液肝素浓度之间的关系。活化凝血时间与同时测定的肝素浓度相关（所有患者样本的r = 0.55，p < 0.001；患者平均值的r = 0.92，p < 0.001）。在我们患者所测得的值范围内，血小板计数、纤维蛋白原和纤维蛋白降解产物不影响ACT与肝素浓度的关系。然而，单个ACT结果的解读因其低精度而受限：重复测定的平均差异为9.2%，通过单次ACT估计肝素浓度的变异系数为32%。两种使用不同激活剂的市售技术给出的结果在数值上有所不同，但彼此相关性良好。两者在估计肝素浓度方面提供了相似的精度。ACT是一种低成本的床旁检测，其准确性和精度能够实现ECMO治疗期间婴儿所需的目标肝素浓度。需要进行多次重复或连续测定才能获得令人满意的精度。这些数据将有助于设计未来的研究，以确定最佳的血清肝素浓度，以提供足够的抗凝效果，同时避免出血并发症。
