Platelet Transfusion for Trauma Resuscitation

Abstract

Purpose of Review To review the role of platelet transfusion in resuscitation for trauma, including normal platelet function and alterations in behavior following trauma, blood product transfusion ratios and the impact of platelet transfusion on platelet function, platelet function assays, risks of platelet transfusion and considerations for platelet storage, and potential adjunct therapies and synthetic platelets. Recent Findings Platelets are a critical component of clot formation and breakdown following injury, and in addition to these hemostatic properties, have a complex role in vascular homeostasis, inflammation, and immune function. Evidence supports that platelets are activated following trauma with several upregulated functions, but under conditions of severe injury and shock are found to be impaired in their hemostatic behaviors. Platelets should be transfused in balanced ratios with red blood cells and plasma during initial trauma resuscitation as this portends improved outcomes including survival. Multiple coagulation assays can be used for goal-directed resuscitation for traumatic hemorrhage; however, these assays each have drawbacks in terms of their ability to measure platelet function. While resuscitation with balanced transfusion ratios is supported by the literature, platelet transfusion carries its own risks such as bacterial infection and lung injury. Platelet supply is also limited, with resource-intensive storage requirements, making exploration of longer-term storage options and novel platelet-based therapeutics attractive. Future focus on a deeper understanding of the biology of platelets following trauma, and on optimization of novel platelet-based therapeutics to maintain hemostatic effects while improving availability should be pursued. Summary While platelet function is altered following trauma, platelets should be transfused in balanced ratios during initial resuscitation. Severe injury and shock can impair platelet function, which can persist for several days following the initial trauma. Assays to guide resuscitation following the initial period as well as storage techniques to extend platelet shelf life are important areas of investigation.

Interplay between Platelet Dysfunction and Vascular Thrombosis in Traumatic Injury

“…Platelets are more hyperreactive as demonstrated by amplified binding to fibrinogen in the presence of increased doses of ADP [53]. This phase is immediate within minutes to hours [54] and is often missed by most studies due to timing of blood sampling.…”

“…Due to the inconsistency in terminology such as 'platelet exhaustion' or 'desensitized, stunned, inactive, post activated, dysfunctional, or degranulated' used to describe the platelet dysfunction in trauma. Perhaps better terminologies such as 'functional anergy' [63] and 'agonist refractoriness' [54] are more apt. It has been opined that what is called maladaptive or dysfunctional platelet in the acute phase of trauma is likely a misnomer, and perhaps it could be an adaptive natural selection mechanism for ensuring survival through possible microvascular thrombosis during the low flow states that kick in following hemorrhage in order to maintain organ perfusion [64].…”

“…Whilst circulating platelets are dysfunctional after trauma [140], platelet transfusion is not associated with restoration of function [54,128,141,142]. The improvement in hemostasis reported in some studies [143] may be attributed to inhibition of fibrinolysis in bleeding trauma patients, but platelets functions remain unaltered compared to those who do not receive transfusion [144].…”