Liver int：一单位血小板对凝血状态影响甚微

肝硬化患者因存在脾功能亢进，血小板破坏增加，通常存在血小板计数减少，导致自发性出血风险增加。为了改善这一状况，临床上通常给予一单位（即一标准成人血小板量）的输注以预防出血，但究竟一标准成人血小板能起到多大的作用？是否能够有效改善患者的凝血状态？如何输注效果会更好？这些仍不清楚。意大利米兰安吉洛比安奇博诺米血友病和血栓形成研究中心Armando Tripodi等人对于上述问题进行了一系列研究，发现输注一个成人标准剂量的血小板仅引起血小板计数轻微增加，而未使凝血酶生成及血栓弹性检测等实验结果正常化。所以为了得到更明显的血小板计数的增加以及相关实验室检查结果的正常化，更加密集的血小板输注以及非输血性治疗药物的使用时必要的。这一结果发表在2013年3月的Liver上。
肝硬化患者均存在不同程度的血小板减少，从而在进行有创性治疗的过程中发生出血的风险增加。为了防止血小板减少性出血，对于肝硬化合并血小板减少的患者通常给予输注一个标准成人血小板剂量来预防出血，然而因为临床研究及实验室检查工具的效力不足的原因，对于临床上有效的血小板阈值仍不明确。体外实验表明，患有肝硬化的患者产生凝血酶的量与正常人群相似，该结果提示肝硬化患者血小板计数至少为100×109/L。
为了评估体内实验及体外研究的相关性，我们研究了26名具有血小板减少的肝硬化患者，进行了36静脉结扎，以便观察输注一个成人标准剂量的血小板能否使血小板上升至之前描述的水平。我们同时采用凝血检测全套：如凝血酶水平测定、血栓弹性测定等方法对输注血小板的效果进行了评估。结果显示：血小板输注对于增加血小板计数作用很小（输注前计数39×109/L (16- 64)，输注后计数52×109/L (19-91)，P < 0.001），对于凝血酶的产生影响也很微弱。这一结果可能与所有的患者再接受血小板输注后其血小板计数水平均低于100×109/L这一目标值。并且，存在异常凝血酶产生水平（低于正常范围下限）的患者人数也未受到输注血小板的影响（输注前为36%，输注后为42%）。输注血小板后血小板计数的微量增加与血栓弹性测定等凝血相关检查结果的改善相平行，但没有患者在输注血小板后达到正常水平。
由此作者得出结论，因输注一个成人标准剂量的血小板仅引起血小板计数轻微增加，而未使凝血酶生成及血栓弹性检测等实验结果正常化。所以为了得到更明显的血小板计数的增加以及相关实验室检查结果的正常化，更加密集的血小板输注以及非输血性治疗药物的使用时必要的。
与肝硬化相关的拓展阅读：

• J Hepatol：肝硬化患者骨折风险增高
• GUT：急性肾损害或将影响肝硬化腹水患者的预后
• GUT：轻度急性肾损害会影响肝硬化腹水患者的预后
• Lancet：长期替诺福韦酯治疗可逆转慢乙肝肝硬化
• J HEPATOL：博赛泼维药物组合治晚期纤维化/肝硬化安全有效
• 丁惠国：肝硬化低钠血症的临床处理
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Global hemostasis tests in patients with cirrhosis before and after prophylactic platelet transfusion.
BACKGROUND/AIMS
Cirrhosis presents with variable degrees of thrombocytopenia that might cause bleeding during invasive procedures. Transfusion of one standard adult platelet dose is often employed to prevent bleeding in thrombocytopenia, but the threshold platelet count that is clinically effective is not well established because clinical studies and laboratory tools to judge on efficacy are insufficient. However, in vitro studies showed that patients with cirrhosis generate as much thrombin as healthy individuals provided that their platelet count is at least 100 × 10(9) /L.
METHODS
To assess the in vivo relevance of these in vitro studies, we investigated 26 thrombocytopenic patients with cirrhosis, undergoing 36 variceal ligations, to see whether transfusion of one standard adult platelet dose was able to attain the above platelet count. We also evaluated the effect of platelet transfusion on such global hemostasis tests as thrombin generation and thromboelastometry.
RESULTS
Transfusion did slightly increase platelet count [pre- vs. post-infusion: 39 × 10(9) /L(16-64) vs. 52 × 10(9) /L(19-91), P < 0.001], without significant effect on thrombin generation, probably because post-transfusion platelet count was less than the target of 100 × 10(9) /L in all patients. In addition, the percentage of patients with abnormal thrombin generation (i.e. below the lower limit of normal range) was scarcely affected by transfusion (pre- vs. post-infusion: 36% vs. 42%). The small post-transfusion increase in platelet count was paralleled by some degree of improvement of thromboelastometry, but none of the patients reached normal values after transfusion.
CONCLUSIONS
Infusing one standard adult platelet dose secures only a small increase in platelet count without normalizing thrombin generation and thromboelastometry tests. To obtain greater increases in platelet count and normalization of laboratory tests more intensive platelet transfusions or treatment with non-transfusional drugs are probably needed.