Andrew M, Schmidt B, Mitchell L, Paes B, Ofosu F
Department of Pediatrics, McMaster University Health Sciences Centre, Chedoke-McMaster Hospitals, Hamilton, Ontario, Canada.
Thromb Haemost. 1990 Feb 19;63(1):27-30.
The ability to generate thrombin is decreased and delayed in plasma from the healthy newborn infant compared to the adult. Only 30 to 50% of peak adult thrombin activity can be produced in neonatal plasma. To test whether this observation can be explained by the low neonatal levels of the contact or vitamin K dependent factors, we measured neonatal thrombin generation after raising the concentration of these factors to adult values. We also determined whether the addition of a variety of blood products to neonatal plasma improved thrombin generation. An amidolytic method was used to quantitate intrinsic (APTT) and extrinsic (PT) pathway thrombin generation in defibrinated pooled cord plasma from healthy term infants. Added individually, factors VII, IX, X or the contact factors (CF) failed to alter the rate or the total amount of thrombin generated in neonatal plasma. In contrast, the addition of prothrombin increased the total amount of thrombin generated to above adult values in both the APTT and the PT systems but did not alter the rate of thrombin generation. The rate of thrombin generation in cord plasma shortened after a combination of II, IX, X and CF was added to the APTT system or II, VII and X to the PT system. In both systems, the total amount of thrombin generated was linearly related to the initial prothrombin concentration. Each of fresh frozen plasma, cryoprecipitate, plasma from platelet concentrates, or factor IX concentrate (in amounts used therapeutically) caused an increase in the total amount of thrombin generated which was related to the increase in prothrombin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
与成年人相比，健康新生儿血浆中凝血酶的生成能力降低且延迟。新生儿血浆中只能产生成人凝血酶峰值活性的30%至50%。为了测试这一观察结果是否可以用新生儿接触或维生素K依赖性因子水平低来解释，我们将这些因子的浓度提高到成人水平后测量了新生儿凝血酶的生成。我们还确定向新生儿血浆中添加各种血液制品是否能改善凝血酶的生成。采用酰胺水解法对健康足月儿去纤维蛋白混合脐血血浆中内源性（活化部分凝血活酶时间，APTT）和外源性（凝血酶原时间，PT）途径的凝血酶生成进行定量。单独添加因子VII、IX、X或接触因子（CF）未能改变新生儿血浆中凝血酶生成的速率或总量。相比之下，添加凝血酶原可使APTT和PT系统中生成的凝血酶总量增加至高于成人水平，但未改变凝血酶生成的速率。在APTT系统中添加II、IX、X和CF或在PT系统中添加II、VII和X后，脐血血浆中凝血酶生成的速率缩短。在两个系统中，生成的凝血酶总量与初始凝血酶原浓度呈线性相关。新鲜冷冻血浆、冷沉淀、血小板浓缩物血浆或因子IX浓缩物（治疗用量）中的每一种都导致生成的凝血酶总量增加，这与凝血酶原浓度的增加有关。（摘要截短于250字）
