Viscoelastic Hemostatic Assays and Outcomes in Traumatic Brain Injury: A Systematic Literature Review

BACKGROUND: Coagulopathy in traumatic brain injury (TBI) occurs frequently and is associated with poor outcomes. Conventional coagulation assays (CCA) traditionally used to diagnose coagulopathy are often not time sensitive and do not assess complete hemostatic function. Viscoelastic hemostatic assays (VHAs) including thromboelastography and rotational thromboelastography provide a useful rapid and comprehensive point-of-care alternative for identifying coagulopathy, which is of significant consequence in patients with TBI with intracranial hemorrhage. METHODS: A systematic review was performed in accordance with PRISMA guidelines to identify studies comparing VHA with CCA in adult patients with TBI. The following differences in outcomes were assessed based on ability to diagnose coagulopathy: mortality, need for neurosurgical intervention, and progression of traumatic intracranial hemorrhage (tICH). RESULTS: Abnormal reaction time (R time), maximum amplitude, and K value were associated with increased mortality in certain studies but not all studies. This association was reflected across studies using different statistical parameters with different outcome definitions. An abnormal R time was the only VHA parameter found to be associated with the need for neurosurgical intervention in 1 study. An abnormal R time was also the only VHA parameter associated with progression of tICH. Overall, many studies also reported abnormal CCAs, mainly activated partial thromboplastin time, to be associated with poor outcomes. CONCLUSIONS: Given the heterogenous nature of the available evidence including methodology and study outcomes, the comparative difference between VHA and CCA in predicting rates of neurosurgical intervention, tICH progression, or mortality in patients with TBI remains inconclusive.