Viscoelastic Testing and Coagulopathy of Traumatic Brain Injury

Abstract

A unique coagulopathy often manifests following traumatic brain injury, leading the clinician down a difficult decision path on appropriate prophylaxis and therapy. Conventional coagulation assays—such as prothrombin time, partial thromboplastin time, and international normalized ratio—have historically been utilized to assess hemostasis and guide treatment following traumatic brain injury. However, these plasma-based assays alone often lack the sensitivity to diagnose and adequately treat coagulopathy associated with traumatic brain injury. Here, we review the whole blood coagulation assays termed viscoelastic tests and their use in traumatic brain injury. Modified viscoelastic tests with platelet function assays have helped elucidate the underlying pathophysiology and guide clinical decisions in a goal-directed fashion. Platelet dysfunction appears to underlie most coagulopathies in this patient population, particularly at the adenosine diphosphate and/or arachidonic acid receptors. Future research will focus not only on the utility of viscoelastic tests in diagnosing coagulopathy in traumatic brain injury, but also on better defining the use of these tests as evidence-based and/or precision-based tools to improve patient outcomes.

Factors Associated with the Development of Coagulopathy after Open Traumatic Brain Injury

“…In our study, we observed a lower PLR in patients with coagulopathy after TBI, which may be due to the massive release of tissue factors after severe open TBI, resulting in activation of the coagulation cascade, PLT consumption, and a subsequent reduction in PLR; however, the incidence and underlying mechanism remain unclear. In addition, a recently published review by Bradbury et al [ 25 ] suggests that platelet dysfunction is the most important cause of coagulopathy in TBI patients, including dysfunction of platelet adhesion, activation, and aggregation, but whether platelet transfusion can improve patient outcomes remains controversial. To the best of our knowledge, our study is the first to report the PLR as a predictor of coagulopathy after TBI.…”

“…Although animal experiments have demonstrated that infusion of FFP can down-regulate the expression of inflammatory pathways and reduce brain swelling [ 29 ], Anglin et al [ 30 ] showed that TBI patients with moderate coagulopathy who underwent FFP were more likely to have a poor prognosis. Thrombocytopenia and platelet dysfunction are central to the development of coagulopathy in TBI patients [ 25 ], platelet transfusion has not been shown to improve mortality in patients with intracranial hemorrhage after TBI, but may instead increase transfusion-related risks in patients with mild TBI, including allergic reactions, acute lung injury, and infections [ 31 ]. In our study, patients presenting with coagulopathy appeared to be more frequently treated with TXA ( p = 0.034), DC ( p < 0.001), and transfusion ( p < 0.001), as well as more transfused volume ( p < 0.001).…”

Hemorrhagic Resuscitation Guided by Viscoelastography in Far-Forward Combat and Austere Civilian Environments: Goal-Directed Whole-Blood and Blood-Component Therapy Far from the Trauma Center

“…The use of VHAs to monitor transfusion requirements has been widely employed in adult and pediatric trauma [61,62], liver transplantation [63], cardiac surgery [64,65], traumatic brain injury [66,67], and postpartum hemorrhage [68]. VHAs have also shown to be cost-neutral compared to CCAs [69].…”

“…While some centers had years of experience with VHAs in trauma, other centers only began VHA use at the start of the trial. Finally, there was a high incidence of traumatic brain injury which confounds causal links to death by exsanguination [67]. Consequently, VHA-guided BCT for trauma remains controversial.…”

Letter to the Editor Regarding “Viscoelastic Hemostatic Assays and Outcomes in Traumatic Brain Injury: A Systematic Literature Review”

“… 19 In contrast, VHAs, including thromboelastography (TEG; Haemonetics SA, Signy, Switzerland) and rotational thromboelastometry (ROTEM; Werfen, Bedford, MA), offer more detailed information about hemostatic potential, measuring the initiation, amplification, propagation, and termination of clot formation. 20 The addition of platelet mapping to these assays also isolates the contribution of platelets to clot strength. 21 As a result, some centers have used VHAs to detect functional differences in coagulation among patients with hemorrhagic stroke, which were not identifiable on CCAs but appeared responsible for hematoma expansion in their respective series.…”