Davenport Patricia, Sola-Visner Martha
Division of Newborn Medicine, Boston Children's Hospital, Boston, MA, United States.
Front Pediatr. 2021 Mar 2;9:627715. doi: 10.3389/fped.2021.627715. eCollection 2021.
The neonatal hemostatic system is strikingly different from that of adults. Among other differences, neonates exhibit hyporeactive platelets and decreased levels of coagulation factors, the latter translating into prolonged clotting times (PT and PTT). Since pre-term neonates have a high incidence of bleeding, particularly intraventricular hemorrhages, neonatologists frequently administer blood products (i.e., platelets and FFP) to non-bleeding neonates with low platelet counts or prolonged clotting times in an attempt to overcome these "deficiencies" and reduce bleeding risk. However, it has become increasingly clear that both the platelet hyporeactivity as well as the decreased coagulation factor levels are effectively counteracted by other factors in neonatal blood that promote hemostasis (i.e., high levels of vWF, high hematocrit and MCV, reduced levels of natural anticoagulants), resulting in a well-balanced neonatal hemostatic system, perhaps slightly tilted toward a prothrombotic phenotype. While life-saving in the presence of active major bleeding, the administration of platelets and/or FFP to non-bleeding neonates based on laboratory tests has not only failed to decrease bleeding, but has been associated with increased neonatal morbidity and mortality in the case of platelets. In this review, we will present a clinical overview of bleeding in neonates (incidence, sites, risk factors), followed by a description of the key developmental differences between neonates and adults in primary and secondary hemostasis. Next, we will review the clinical tests available for the evaluation of bleeding neonates and their limitations in the context of the developmentally unique neonatal hemostatic system, and will discuss current and emerging approaches to more accurately predict, evaluate and treat bleeding in neonates.
新生儿止血系统与成人的显著不同。除其他差异外，新生儿的血小板反应性低下，凝血因子水平降低，后者导致凝血时间延长（PT和PTT）。由于早产儿出血的发生率很高，尤其是脑室内出血，新生儿科医生经常给血小板计数低或凝血时间延长的非出血性新生儿输注血液制品（即血小板和新鲜冰冻血浆），试图克服这些“缺陷”并降低出血风险。然而，越来越清楚的是，新生儿血液中促进止血的其他因素（即高水平的血管性血友病因子、高血细胞比容和平均红细胞体积、天然抗凝剂水平降低）有效地抵消了血小板反应性低下以及凝血因子水平降低的情况，从而形成了一个平衡良好的新生儿止血系统，可能略微倾向于血栓前表型。虽然在有活动性大出血时输血可挽救生命，但根据实验室检查结果给非出血性新生儿输注血小板和/或新鲜冰冻血浆不仅未能减少出血，而且在输注血小板的情况下还与新生儿发病率和死亡率增加有关。在这篇综述中，我们将介绍新生儿出血的临床概况（发生率、部位、危险因素），接着描述新生儿和成人在初级和次级止血方面的关键发育差异。接下来，我们将回顾用于评估出血新生儿的临床检查及其在发育独特的新生儿止血系统背景下的局限性，并将讨论当前和新出现的更准确预测、评估和治疗新生儿出血的方法。
