TRANSFUSION AND INFUSION THERAPY FOR MASSIVE BLOOD LOSS. PART 4. PHYSIOLOGICAL PREREQUISITES AND LIMITATIONS OF PLATELETS TRANSFUSION FOR HAEMOSTATIC RESUSCITATION

Abstract

Platelets are the main component of primary haemostasis and participate in secondary, coagulation haemostasis. When bleeding from small vessels, primary (platelet) hemostasis can ensure the thrombus's stability, which is sufficient to stop the bleeding. In case of damage to medium and large vessels, stopping bleeding begins with the activation of platelets, but also requires the activation of the coagulation cascade with the involvement of internal and external coagulation pathways. Blood coagulation factors involved in internal, external and general coagulation pathways not only circulate in the blood but are carried by platelets. In addition, actin and myosin contained in platelets, take an active part already in the final phase of thrombus formation – in clot retraction. Platelets also contain growth factors that stimulate the healing of damaged blood vessels. For more than a decade, platelets have been an integral part of haemostatic resuscitation in cases of massive bleeding in trauma and wounds. The optimal ratio of platelets to red blood cells (RBC) and fresh frozen plasma (FFP) in trauma is 1:1:1, that is, to include a considerable number of platelets. With other variants of surgical massive bleeding, the optimal ratio may be different and the proportion of platelets to RBC, and the number of platelets is smaller. Platelets, like clotting factors, are consumed during thrombus formation and are also passively lost with the outflowing blood. The rate of loss of platelets is sometimes not directly proportional to the amount of blood loss and also depends on the haematocrit. Although during a full-scale war, the frequency of the development of massive bleeding in Ukraine is the highest in the world, to date, the logistical problems with the availability of platelets, especially at the stage of initial resuscitation, are still not resolved. Therefore, in this article, we provide ways to solve the situation, depending on the available resources. In civilian settings, the problem with platelets most often occurs because of intraoperative or traumatic bleeding in the background of taking antiplatelet agents, that is, inhibitors of platelet function. Taking antiplatelet agents can increase bleeding, and the physician needs to know how to restore lost platelet functions or how to replace these lost functions with platelet concentrate. In this publication, we will present the pathophysiological rationale for the importance of early recovery of the first phase of haemostasis - platelet aggregation by transfusion of platelet concentrate in case of traumatic massive bleeding. In addition, we present some methods that contribute to the preservation of platelets, as well as improving their functional activity. Other factors that increase the risk of developing MC are thrombocytopenia and thrombocytopenia caused by hereditary and acquired factors. Although haematologists treat such patients and should be involved as consultants, in this article we will briefly outline the most common treatment methods prescribed by haematologists. The factors that lead to platelet deficiency in the blood vary, but life-threatening bleeding treatment by platelet concentrate transfusion can be a common solution in many situations. If it is not possible to transfuse a sufficient number of platelets concentrate during life-threatening bleeding in patients with thrombocytopenia and platelet dysfunction, it may be transfused a fresh whole-blood.