Platelet Dysfunction is an Early Marker for Traumatic Brain Injury-Induced Coagulopathy

Traumatic brain injury: Symptoms to systems in the 21st century

Severe traumatic brain injury (TBI) is a devastating injury with a mortality of ∼ 25-30 %. Despite decades of high-quality research, no drug therapy has reduced mortality. Why is this so? We argue two contributing factors for the lack of effective drug therapies include the use of specific-pathogen free (SPF) animals for translational research and the flawed practice of single-nodal targeting for drug design. A revolution is required to better understand how the whole body responds to TBI, identify new markers of its progression, and discover new system-acting drugs to treat it. In this review, we present a brief history of TBI, discuss its system's pathophysiology and propose a new research strategy for the 21st century. TBI progression develops from injury signals radiating from the primary impact, which can cause local ischemia, hemorrhage, excitotoxicity, cellular depolarization, immune dysfunction, sympathetic hyperactivity, blood-brain barrier breach, coagulopathy and whole-body dysfunction. Metabolic reprograming of immune cells drives neuroinflammation and secondary injury processes. We propose if sympathetic hyperactivity and immune cell activation can be corrected early, cardiovascular function and endothelial-glycocalyx-mitochondrial coupling can be restored, and secondary injury minimized with improved patient outcomes. The therapeutic goal is to switch the injury phenotype to a healing phenotype by restoring homeostasis and maintaining sufficient tissue O2 delivery. We have been developing a small-volume fluid therapy comprising adenosine, lidocaine and magnesium (ALM) to treat TBI and have shown that it blunts the CNS-stress response, supports cardiovascular function and reduces secondary injury. Future research will investigate its suitability for human translation.

The Impact of ADP Inhibition on Traumatic Brain Injury Outcomes

Platelet inhibition correlates with severity of traumatic brain injury and may be associated with mortality. Adenosine diphosphate participates in platelet aggregation via the activation of the ADP receptors, P2Y1 and P2Y12. Prior work suggests this ADP pathway is significant in managing patients with head injuries. This study aimed to measure the influence of ADP inhibition on outcomes after a traumatic brain injury (TBI), as measured by thromboelastography with platelet mapping (TEG-PM). Outcomes were defined as (a) hospital length of stay; (b) ICU length of stay, (c) mortality, and (d) progression of hemorrhage on CT. The resulting cohort was split into quartiles to compare the effect of increasingly inhibited ADP values on the identified outcomes. Comparisons of 2 groups of patients were also conducted, one defined by ADP inhibition less than or equal to 60% and the other group by ADP inhibition of greater than 60%. 98 patients were included in final analysis, with 72.4% having ADP inhibition less than 60%. These patients were significantly older and had lower global injury severity scores (ISSs), although their head-specific ISS was equivalent. Compared to the group with ADP inhibition over 60%, there was no significant difference in mortality, hospital or ICU length of stay, or progression of lesion on CT. Patients with ADP less than 60% inhibited had smaller ISS and higher GCS, indicating they were less injured than those with greater ADP inhibition, consistent with prior literature. The equivalent ICU and hospital length of stay and mortality suggests that ADP inhibition plays a smaller role in outcomes. Additional study with a larger sample size and guideline-based assessments is necessary to further define the impact of ADP inhibition and to determine the role of platelet transfusion in this population.

Platelet Dynamics in Neurodegenerative Disorders: Investigating the Role of Platelets in Neurological Pathology

Background: Neurological disorders, particularly those associated with aging, pose significant challenges in early diagnosis and treatment. The identification of specific biomarkers, such as platelets (PLTs), has emerged as a promising strategy for early detection and intervention in neurological health. This systematic review aims to explore the intricate relationship between PLT dynamics and neurological health, focusing on their potential role in cognitive functions and the pathogenesis of cognitive disorders. Methods: Adhering to PRISMA guidelines, a comprehensive search strategy was employed in the PubMed and Scholar databases to identify studies on the role of PLTs in neurological disorders published from 2013 to 2023. The search criteria included studies focusing on PLTs as biomarkers in neurological disorders, their dynamics, and their potential in monitoring disease progression and therapy effectiveness. Results: The systematic review included 104 studies, revealing PLTs as crucial biomarkers in neurocognitive disorders, acting as inflammatory mediators. The findings suggest that PLTs share common features with altered neurons, which could be utilised for monitoring disease progression and evaluating the effectiveness of treatments. PLTs are identified as significant biomarkers for detecting neurological disorders in their early stages and understanding the pathological events leading to neuronal death. Conclusions: The systematic review underscores the critical role of PLTs in neurological disorders, highlighting their potential as biomarkers for the early detection and monitoring of disease progression. However, it also emphasises the need for further research to solidify the use of PLTs in neurological disorders, aiming to enhance early diagnosis and intervention strategies.

Scenario Decision-Making About Plasma and Platelet Transfusion for Intracranial Monitor Placement: Cross-Sectional Survey of Pediatric Intensivists and Neurosurgeons

OBJECTIVES

To report pediatric intensivists' and pediatric neurosurgeons' responses to case-based scenarios about plasma and platelet transfusions before intracranial pressure (ICP) monitor placement in children with severe traumatic brain injury (TBI).

DESIGN

Cross-sectional, electronic survey to evaluate reported plasma and platelet transfusion decisions in eight scenarios of TBI in which ICP monitor placement was indicated.

SETTING

Survey administered through the Pediatric Acute Lung Injury and Sepsis Investigators and the American Association of Neurologic Surgeons.

SUBJECTS

Pediatric intensivists and pediatric neurosurgeons.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 184 participants responded (85 identified as pediatric intensivists and 54 as pediatric neurosurgeons). In all eight scenarios, the majority of respondents reported that they would base their decision-making about plasma transfusion on international normalized ratio (INR) alone (60-69%), or platelet transfusion on platelet count alone (83-86%). Pediatric intensivists, as opposed to pediatric neurosurgeons, more frequently reported that they would have used viscoelastic testing in their consideration of plasma transfusion (32% vs. 7%, p < 0.001), as well as to guide platelet transfusions (29 vs. 8%, p < 0.001), for the case-based scenarios. For all relevant case-based scenarios, pediatric neurosurgeons in comparison with pediatric reported that they would use a lower median (interquartile range [IQR]) INR threshold for plasma transfusion (1.5 [IQR 1.4-1.7] vs. 2.0 [IQR 1.5-2.0], p < 0.001). Overall, in all respondents, the reported median platelet count threshold for platelet transfusion in the case-based scenario was 100 (IQR 50-100) ×10 9 /L, with no difference between specialties.

CONCLUSIONS

Despite little evidence showing efficacy, when we tested specialists' decision-making, we found that they reported using INR and platelet count in pediatric case-based scenarios of TBI undergoing ICP monitor placement. We also found that pediatric intensivists and pediatric neurosurgeons had differences in decision-making about the scenarios.

Point-of-care, goal-directed management of bleeding in trauma patients

PURPOSE OF REVIEW

The purpose of this review is to consider the clinical value of point-of-care (POC) testing in coagulopathic trauma patients with traumatic brain injury (TBI) and trauma-induced coagulopathy (TIC).

RECENT FINDINGS

Patients suffering from severe TBI or TIC are at risk of developing pronounced haemostatic disorders. Standard coagulation tests (SCTs) are insufficient to reflect the complexity of these coagulopathies. Recent evidence has shown that viscoelastic tests (VETs) identify haemostatic disorders more rapidly and in more detail than SCTs. Moreover, VET results can guide coagulation therapy, allowing individualised treatment, which decreases transfusion requirements. However, the impact of VET on mortality remains uncertain. In contrast to VETs, the clinical impact of POC platelet function testing is still unproven.

SUMMARY

POC SCTs are not able to characterise the complexity of trauma-associated coagulopathy. VETs provide a rapid estimation of underlying haemostatic disorders, thereby providing guidance for haemostatic therapy, which impacts allogenic blood transfusion requirements. The value of POC platelet function testing to identify platelet dysfunction and guide platelet transfusion is still uncertain.

Age, admission platelet count, and mortality in severe isolated traumatic brain injury: A retrospective cohort study

BACKGROUND

We asked whether patients >50 years of age with acute traumatic brain injury (TBI) present with lower platelet counts and whether lower platelet counts are independently associated with mortality.

METHODS

We combined trauma registry and laboratory data on a retrospective cohort of all patients ≥18 years of age admitted to our Level 1 US regional trauma center 2015-2021 with severe (Head Abbreviated Injury Score [AIS] ≥3), isolated (all other AIS <3) TBI who had a first platelet count within 1 h of arrival. Age and platelet count were assessed continuously and as groups (age 18-50 vs. >50, platelet normals, and at conventional transfusion thresholds). Outcomes such as mean admission platelet counts and in-hospital mortality were assessed categorically and with logistic regression.

RESULTS

Of 44,056 patients, 1298 (3%, median age: 52 [IQR 33,68], 76.1% male) met all inclusion criteria with no differences between younger and older age groups for (ISS; 18 [14,26] vs. 17 [14,26], p = .22), New ISS (NISS; 29 [19,50] vs. 28 [17,50], p = .36), or AIS-Head (4 [3,5] vs. 4 [3,5]; p = .87). Patients aged >50 had lower admission platelet counts (219,000 ± 93,000 vs. 242,000 ± 76,000/μL; p < .001) and greater in-hospital mortality (24.5% vs. 15.6%, p < .001) than those 18-50. In multivariable regression, firearms injuries (OR9.08), increasing age (OR1.004), NISS (OR1.007), and AIS-Head (OR1.05), and decreasing admission platelet counts (OR0.998) were independently associated with mortality (p < .001-.041). Platelet transfusion in the first 4 h of care was more frequent among older patients (p < .001).

CONCLUSIONS

Older patients with TBI had lower admission platelet counts, which were independently associated with greater mortality.

Acute Haemostatic Depletion and Failure in Patients with Traumatic Brain Injury (TBI): Pathophysiological and Clinical Considerations

BACKGROUND

Because of the aging population, the number of low falls in elderly people with pre-existing anticoagulation is rising, often leading to traumatic brain injury (TBI) with a social and economic burden. Hemostatic disorders and disbalances seem to play a pivotal role in bleeding progression. Interrelationships between anticoagulatoric medication, coagulopathy, and bleeding progression seem to be a promising aim of therapy.

METHODS

We conducted a selective search of the literature in databases like Medline (Pubmed), Cochrane Library and current European treatment recommendations using relevant terms or their combination.

RESULTS

Patients with isolated TBI are at risk for developing coagulopathy in the clinical course. Pre-injury intake of anticoagulants is leading to a significant increase in coagulopathy, so every third patient with TBI in this population suffers from coagulopathy, leading to hemorrhagic progression and delayed traumatic intracranial hemorrhage. In an assessment of coagulopathy, viscoelastic tests such as TEG or ROTEM seem to be more beneficial than conventional coagulation assays alone, especially because of their timely and more specific gain of information about coagulopathy. Furthermore, results of point-of-care diagnostic make rapid "goal-directed therapy" possible with promising results in subgroups of patients with TBI.

CONCLUSIONS

The use of innovative technologies such as viscoelastic tests in the assessment of hemostatic disorders and implementation of treatment algorithms seem to be beneficial in patients with TBI, but further studies are needed to evaluate their impact on secondary brain injury and mortality.

Relationship between platelet indices and red cell distribution width and short-term mortality in traumatic brain injury with 30-day mortality

OBJECTIVE

This study aimed at investigating whether there is a relationship between 7- or 30-day mortality and mean platelet volume, platelet distribution width, platelet count-to-total lymphocyte count ratio, or red cell distribution width in patients with traumatic brain injury.

METHODS

We retrospectively analyzed intensive care unit patients with traumatic brain injury. We recorded patients' ages; genders; diagnoses; Glasgow Coma Scale scores; length of intensive care unit stay (in days); mean platelet volume, platelet distribution width, platelet count-to-total lymphocyte count ratio, and red cell distribution width values upon hospital admission; and health on the 7th and 30th days of their stays.

RESULTS

We analyzed data from 110 patients. Of these, 84 (76.4%) were male and 26 (23.6%) were female. On the 7- and 30-day mortality evaluations, compared to the living patients, the deceased patients had a significantly higher median age and a significantly lower median Glasgow Coma Scale. Thus, increased age and lower Glasgow Coma Scale scores were associated with increased 7- and 30-day mortality rates. mean platelet volume and platelet distribution width values were similar in living and deceased patients. platelet count-to-total lymphocyte count ratio values were lower in deceased patients, but this difference was not statistically significant. Within 30 days after traumatic brain injury, deceased patients' red cell distribution width values were significantly elevated in deceased patients compared to those of living patients.

CONCLUSION

Mean platelet volume, platelet distribution width, and platelet count-to-total lymphocyte count ratio values were not associated with 7- and 30-day mortality, whereas only elevated red cell distribution width was associated with 30-day mortality.

SHock-INduced Endotheliopathy (SHINE): A mechanistic justification for viscoelastography-guided resuscitation of traumatic and non-traumatic shock

Irrespective of the reason for hypoperfusion, hypocoagulable and/or hyperfibrinolytic hemostatic aberrancies afflict up to one-quarter of critically ill patients in shock. Intensivists and traumatologists have embraced the concept of SHock-INduced Endotheliopathy (SHINE) as a foundational derangement in progressive shock wherein sympatho-adrenal activation may cause systemic endothelial injury. The pro-thrombotic endothelium lends to micro-thrombosis, enacting a cycle of worsening perfusion and increasing catecholamines, endothelial injury, de-endothelialization, and multiple organ failure. The hypocoagulable/hyperfibrinolytic hemostatic phenotype is thought to be driven by endothelial release of anti-thrombogenic mediators to the bloodstream and perivascular sympathetic nerve release of tissue plasminogen activator directly into the microvasculature. In the shock state, this hemostatic phenotype may be a counterbalancing, yet maladaptive, attempt to restore blood flow against a systemically pro-thrombotic endothelium and increased blood viscosity. We therefore review endothelial physiology with emphasis on glycocalyx function, unique biomarkers, and coagulofibrinolytic mediators, setting the stage for understanding the pathophysiology and hemostatic phenotypes of SHINE in various etiologies of shock. We propose that the hyperfibrinolytic phenotype is exemplified in progressive shock whether related to trauma-induced coagulopathy, sepsis-induced coagulopathy, or post-cardiac arrest syndrome-associated coagulopathy. Regardless of the initial insult, SHINE appears to be a catecholamine-driven entity which early in the disease course may manifest as hyper- or hypocoagulopathic and hyper- or hypofibrinolytic hemostatic imbalance. Moreover, these hemostatic derangements may rapidly evolve along the thrombohemorrhagic spectrum depending on the etiology, timing, and methods of resuscitation. Given the intricate hemochemical makeup and changes during these shock states, macroscopic whole blood tests of coagulative kinetics and clot strength serve as clinically useful and simple means for hemostasis phenotyping. We suggest that viscoelastic hemostatic assays such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are currently the most applicable clinical tools for assaying global hemostatic function-including fibrinolysis-to enable dynamic resuscitation with blood products and hemostatic adjuncts for those patients with thrombotic and/or hemorrhagic complications in shock states.

Coagulopathy in Isolated Traumatic Brain Injury: Myth or Reality

INTRODUCTION

Traumatic Brain Injury (TBI) has been shown to be associated with altered hemostasis and coagulopathy, that correlates with worsening secondary injury and clinical outcomes. Isolated Traumatic Brain Injury (iTBI), that is TBI without significant extracranial injuries, has also been shown to be associated with systemic coagulopathy and derangements in hemostasis.

METHODS

Literature Review.

RESULTS

Present your results in logical sequence in the text, tables, and figures, giving the main or most important findings first. Do not repeat all the data in the tables or figures in the text; emphasize or summarize only the most important observations. Provide data on all primary and secondary outcomes identified in the Methods section. Give numeric results not only as derivatives (e.g. percentages) but also as the absolute numbers from which the derivatives were calculated, and specify the statistical significance attached to them, if any.

DISCUSSION

In this review, we provide an overview of the pathophysiology of the hemostatic disturbances caused by iTBI, review key clinical findings and discrepancies in the way this question has been approached, describe the use and role of global viscoelastic assays such as the thromboelastrogram, and detail principles for reversal of pre-injury blood thinners.

CONCLUSIONS

iTBI is clearly associated with the development of coagulopathy, but the extent to which it occurs is confounded by the fact that many of the studies have included patients with moderate extracranial trauma into the iTBI category. The coagulopathy itself has been better studied in preclinical models, and the mechanisms driving it suggest a pattern consistent with disseminated intravascular coagulation with hyperfibrinolysis. We provide pragmatic clinical takeaways and suggestions for future research.

Effects of Guideline-Based Correction of Platelet Inhibition on Outcomes in Moderate to Severe Isolated Blunt Traumatic Brain Injury

Platelet dysfunction has been demonstrated after traumatic brain injury (TBI) regardless of the use of platelet inhibitors. The purpose of this study was to determine the efficacy of a platelet-mapping thromboelastography (PM-TEG) in predicting TBI patients who would benefit from platelet transfusion. We hypothesized that adenosine diphosphate (ADP) and arachadonic acid (AA) inhibition in patients with TBI is associated with increased mortality and can be corrected with platelet transfusion. This is a retrospective review of patients admitted to a level 1 trauma center from January 2016 through September 2017 with moderate to severe blunt TBI (msTBI), defined by an initial Glasgow Coma Scale (GCS) ≤12 with intracranial hemorrhage. Patients received PM-TEG. Those with platelet dysfunction (ADP or AA inhibition ≥60%) received one unit of platelets followed by repeat PM-TEG, until inhibition <60% or three units of platelets. Cohorts were defined as patients initially without (NPI) and with (PI) inhibition and subdivided into those whose inhibition corrected (PI-C) versus those whose did not correct (PI-NC). From 69 patients with isolated blunt TBI, 40 (58%) presented with NPI, 29 (42%) with PI. Of those with PI, 16 (55%) were with PI-C and 13 (45%) with PI-NC. Platelet inhibition in msTBI patients undergoing guideline-based transfusion is associated with age and GCS and an increase in mortality. Platelet inhibition seems to have a more adverse effect on patients >55 years of age or with GCS <8. Correction of platelet inhibition normalized mortality to that of NPI.

Platelet Transfusion for Trauma Resuscitation

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.

Multiplate Platelet Function Testing upon Emergency Room Admission Fails to Provide Useful Information in Major Trauma Patients Not on Platelet Inhibitors

Platelet dysfunction is a suggested driver of trauma-induced coagulopathy. However, there is still a paucity of data regarding the impact of injury pattern on platelet function and the association of platelet dysfunction on transfusion requirements and mortality. In this retrospective cohort study, patients were grouped into those with isolated severe traumatic brain injury (TBI group), those with major trauma without TBI (MT group), and a combination of both major trauma and traumatic brain injury (MT + TBI group). Platelet function was assessed by whole blood impedance aggregometry (Multiplate^®, MP). Three different platelet activators were used: adenosine-diphosphate (ADP test), arachidonic acid (ASPI test), and thrombin activated peptide-6 (TRAP test). Blood transfusion requirements within 6 h and 24 h and the association of platelet dysfunction on mortality was investigated. A total of 328 predominantly male patients (75.3%) with a median age of 53 (37–68) years and a median ISS of 29 (22–38) were included. No significant difference between the TBI group, the MT group, and the MT + TBI group was detected for any of the investigated platelet function tests. Unadjusted and adjusted for platelet count, the investigated MP assays revealed no significant group differences upon ER admission and were not able to sufficiently predict massive transfusion, neither within the first 6 h nor for the first 24 h after hospital admission. No association between platelet dysfunction measured by MP upon ER admission and mortality was observed. Conclusion: Injury pattern did not specifically impact platelet function measurable by MP. Platelet dysfunction upon ER admission measurable by MP was not associated with transfusion requirements and mortality. The clinical relevance of platelet function testing by MP in trauma patients not on platelet inhibitors is questionable.

Traumatic brain injury patients with platelet inhibition receiving platelet transfusion demonstrate decreased need for neurosurgical intervention and decreased mortality

BACKGROUND

Platelet dysfunction is known to occur in patients with traumatic brain injury (TBI), and the correction of platelet dysfunction may prevent hemorrhagic progression in TBI. Thromboelastography with platelet mapping (TEG-PM; Haemonetics) evaluates the degree of platelet function inhibition through the adenosine diphosphate (ADP) and arachidonic acid (AA) pathways. We hypothesized that ADP and AA inhibition would improve with the transfusion of platelets in patients with TBI.

METHODS

A retrospective review was conducted at a Level I trauma center of all patients presenting with TBI from December 2019 to December 2020. Per a practice management guideline, a platelet mapping assay was obtained on all patients with TBI upon admission. If ADP or AA was found to be inhibited (>60%), the patient was transfused 1 unit of platelets and a repeat platelet mapping assay was ordered. Demographic data, laboratory values, and outcomes were analyzed.

RESULTS

Over the 13-month study period, 453 patients with TBI underwent TEG-PM with a protocol adherence rate of 66.5% resulting in a total of 147 patients who received platelets for ADP and/or AA inhibition; of those, 107 underwent repeat TEG-PM after platelets were administered. With the administration of platelets, ADP (p < 0.0001), AA (p < 0.0001), and MA (p = 0.0002) all significantly improved. Of 330 patients with TBI not taking antiplatelet medications, 50.9% showed inhibition in ADP and/or AA. If AA or ADP inhibition was noted on admission, mortality was increased (p = 0.0108). If ADP improved with platelet administration, the need for neurosurgical intervention was noted to decrease (p = 0.0182).

CONCLUSION

Patients with TBI and platelet inhibition may benefit from the administration of platelets to correct platelet dysfunction. Thromboelastography with platelet mapping may be implemented in the initial workup of patients presenting with TBI to assess platelet dysfunction and provide prognostic information, which may guide treatment.

LEVEL OF EVIDENCE

Therapeutic / Care Management, level III.

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.

Coagulopathy and Traumatic Brain Injury: Overview of New Diagnostic and Therapeutic Strategies

Coagulopathy is a common sequela of traumatic brain injury. Consumptive coagulopathy and secondary hyperfibrinolysis are associated with hypercoagulability. In addition, fibrinolytic pathways are hyperactivated as a result of vascular endothelial cell damage in the injured brain. Coagulation and fibrinolytic parameters change dynamically to reflect these pathologies. Fibrinogen is consumed and degraded after injury, with fibrinogen concentrations at their lowest 3-6 h after injury. Hypercoagulability causes increased fibrinolytic activity, and plasma levels of D-dimer increase immediately after traumatic brain injury, reaching a maximum at 3 h. Owing to disseminated intravascular coagulation in the presence of fibrinolysis, the bleeding tendency is highest within the first 3 h after injury, and often a condition called “talk and deteriorate” occurs. In neurointensive care, it is necessary to measure coagulation and fibrinolytic parameters such as fibrinogen and D-dimer routinely to predict and prevent the development of coagulopathy and its negative outcomes. Currently, the only evidence-based treatment for traumatic brain injury with coagulopathy is tranexamic acid in the subset of patients with mild-to-moderate traumatic brain injury. Coagulation and fibrinolytic parameters should be closely monitored, and treatment should be considered on a patient-by-patient basis.

A Machine Learning Approach for the Prediction of Traumatic Brain Injury Induced Coagulopathy

Background: Traumatic brain injury-induced coagulopathy (TBI-IC), is a disease with poor prognosis and increased mortality rate.

Objectives: Our study aimed to identify predictors as well as develop machine learning (ML) models to predict the risk of coagulopathy in this population.

Methods: ML models were developed and validated based on two public databases named Medical Information Mart for Intensive Care (MIMIC)-IV and the eICU Collaborative Research Database (eICU-CRD). Candidate predictors, including demographics, family history, comorbidities, vital signs, laboratory findings, injury type, therapy strategy and scoring system were included. Models were compared on area under the curve (AUC), accuracy, sensitivity, specificity, positive and negative predictive values, and decision curve analysis (DCA) curve.

Results: Of 999 patients in MIMIC-IV included in the final cohort, a total of 493 (49.35%) patients developed coagulopathy following TBI. Recursive feature elimination (RFE) selected 15 variables, including international normalized ratio (INR), prothrombin time (PT), sepsis related organ failure assessment (SOFA), activated partial thromboplastin time (APTT), platelet (PLT), hematocrit (HCT), red blood cell (RBC), hemoglobin (HGB), blood urea nitrogen (BUN), red blood cell volume distribution width (RDW), creatinine (CRE), congestive heart failure, myocardial infarction, sodium, and blood transfusion. The external validation in eICU-CRD demonstrated that adapting boosting (Ada) model had the highest AUC of 0.924 (95% CI: 0.902–0.943). Furthermore, in the DCA curve, the Ada model and the extreme Gradient Boosting (XGB) model had relatively higher net benefits (ie, the correct classification of coagulopathy considering a trade-off between false- negatives and false-positives)—over other models across a range of threshold probability values.

Conclusions: The ML models, as indicated by our study, can be used to predict the incidence of TBI-IC in the intensive care unit (ICU).

Coagulopathy and Progression of Intracranial Hemorrhage in Traumatic Brain Injury: Mechanisms, Impact, and Therapeutic Considerations

BACKGROUND

Traumatic brain injury (TBI) remains one of the most challenging health and socioeconomic problems of our times. Clinical courses may be complicated by hemostatic abnormalities either pre-existing or developing with TBI.

OBJECTIVE

To review frequencies, patterns, mechanisms, novel approaches to diagnostics, treatment, and outcomes of hemorrhagic progression and coagulopathy after TBI.

METHODS

Selective review of the literature in the databases Medline (PubMed) and Cochrane Reviews using different combinations of the relevant search terms was conducted.

RESULTS

Of the patients, 20% with isolated TBI display laboratory coagulopathy upon hospital admission with profound effect on morbidity and mortality. Preinjury use of antithrombotic agents may be associated with higher rates of hemorrhagic progression and delayed traumatic intracranial hemorrhage. Further testing may display various changes affecting platelet function/numbers, pro- and/or anticoagulant factors, and fibrinolysis as well as interactions between brain tissues, vascular endothelium, mechanisms of inflammation, and blood flow dynamics. The nature of hemostatic disruptions after TBI remains elusive but current evidence suggests the presence of both a hyper- and hypocoagulable state with possible overlap and lack of distinction between phases and states. More "global" hemostatic assays, eg, viscoelastic and thrombin generation tests, may provide more detailed and timely information on the overall hemostatic potential thereby allowing early "goal-directed" therapies.

CONCLUSION

Whether timely and targeted management of hemostatic abnormalities after TBI can protect against secondary brain injury and thereby improve outcomes remains elusive. Innovative technologies for diagnostics and monitoring offer windows of opportunities for precision medicine approaches to managing TBI.

Viscoelastic Testing and Coagulopathy of Traumatic Brain Injury

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.

The Pathophysiology and Management of Hemorrhagic Shock in the Polytrauma Patient

The recognition and management of life-threatening hemorrhage in the polytrauma patient poses several challenges to prehospital rescue personnel and hospital providers. First, identification of acute blood loss and the magnitude of lost volume after torso injury may not be readily apparent in the field. Because of the expression of highly effective physiological mechanisms that compensate for a sudden decrease in circulatory volume, a polytrauma patient with a significant blood loss may appear normal during examination by first responders. Consequently, for every polytrauma victim with a significant mechanism of injury we assume substantial blood loss has occurred and life-threatening hemorrhage is progressing until we can prove the contrary. Second, a decision to begin damage control resuscitation (DCR), a costly, highly complex, and potentially dangerous intervention must often be reached with little time and without sufficient clinical information about the intended recipient. Whether to begin DCR in the prehospital phase remains controversial. Furthermore, DCR executed imperfectly has the potential to worsen serious derangements including acidosis, coagulopathy, and profound homeostatic imbalances that DCR is designed to correct. Additionally, transfusion of large amounts of homologous blood during DCR potentially disrupts immune and inflammatory systems, which may induce severe systemic autoinflammatory disease in the aftermath of DCR. Third, controversy remains over the composition of components that are transfused during DCR. For practical reasons, unmatched liquid plasma or freeze-dried plasma is transfused now more commonly than ABO-matched fresh frozen plasma. Low-titer type O whole blood may prove safer than red cell components, although maintaining an inventory of whole blood for possible massive transfusion during DCR creates significant challenges for blood banks. Lastly, as the primary principle of management of life-threatening hemorrhage is surgical or angiographic control of bleeding, DCR must not eclipse these definitive interventions.

Role of Monocyte-to-lymphocyte Ratio, Mean Platelet Volume-to-Platelet Count Ratio, C-Reactive Protein and Erythrocyte Sedimentation Rate as Predictor of Severity in Secondary Traumatic Brain Injury: A Literature Review

BACKGROUND: Secondary traumatic brain injury (TBI) is injury to the brain following primary TBI because of neuroinflammation as consequences of neuronal and glial cell injury which cause release of various inflammation cytokine and chemokine. Biomarker examination to predict the severity of secondary TBI is important to provide appropriate treatment to the patient. This article reviews possibility several common laboratory parameter such as monocyte-to-lymphocyte ratio (MLR), mean platelet volume-to-platelet count (PC) ratio (MPV-PCR), c-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) to predict severity of secondary TBI. LITERATURE REVIEW: TBI activates microglia which increase infiltration and proliferation of monocyte. Neuroinflammation also increases thrombopoiesis which leads to increase megakaryocytes production. In the other hand, due to disruption of brain blood vessels because of trauma, coagulation cascade is also activated and leads to consumptive coagulopathy. These are reflected as high monocyte count, low PC, and high MPV. Lymphocyte count is reported low in TBI especially in poor outcome patients. CRP is an acute phase reactant that increased in inflammation condition. In TBI, increased production of Interleukin-6 leads to increase CRP production. In head injured patients, ESR level does not increase significantly in the acute phase of inflammation but last longer when compared to CRP. CONCLUSION: MLR, MPV-PCR, CRP, and ESR could be predictor of severity in secondary TBI.

Use of Thromboelastography in the Evaluation and Management of Patients With Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Supplemental Digital Content is available in the text.

Traumatic brain injury is associated with coagulopathy that increases mortality risk. Viscoelastic hemostatic assays such as thromboelastography (Haemonetics SA, Signy, Switzerland) provide rapid coagulopathy assessment and may be particularly useful for goal-directed treatment of traumatic brain injury patients. We conducted a systematic review to assess thromboelastography in the evaluation and management of coagulopathy in traumatic brain injury patients.

Characterization of antiplatelet response to low-dose cangrelor utilizing platelet function testing in neuroendovascular patients

STUDY OBJECTIVES

The optimal antiplatelet therapy for emergent neuroendovascular stenting is uncertain. Cangrelor is an intravenous P2Y12 inhibitor that is an attractive option due its favorable pharmacokinetic profile and ease of measurability but optimal dosing remains unclear. The primary objective of this study is to characterize the dose response of low dose cangrelor (<2 mcg/kg/min) with the utilization of platelet function testing (PFT).

DESIGN

A retrospective review of all patients treated with cangrelor for either procedural stenting or bridging was conducted between January 1st, 2019 and October 31st, 2020. Seventy-two patients met inclusion criteria. An in-depth analysis of dose response to low dose cangrelor based on PFT was performed.

PATIENTS

Neuroendovascular patients treated with cangrelor.

SETTING

Albany Medical Center Hospital.

INTERVENTION AND MAIN RESULTS

Patients who underwent procedural stenting were given a bolus of 5 mcg/kg and an initial infusion rate of either 0.75 mcg/kg/min or 1 mcg/kg/min. Patients who were bridged with cangrelor were administered an initial infusion rate of 0.75 mcg/kg/min or 1 mcg/kg/min. Twelve patient's doses were titrated to achieve a platelet reactivity unit (PRU) between 50-150; three patient's doses were titrated multiple times. Based on initial PFT results, utilizing the 1 mcg/kg/min maintenance dose resulted in more patients being in the acceptable (10-180) and desired (50-150) PRU range than the 0.75 mcg/kg/min dose (47% vs 56% and 70% vs 80%, respectively). Final recorded PRU results showed that 64% of patients had PRUs in the optimal range (50-150) and 88% of patients had PRUs in the desire range (10-180).

CONCLUSIONS

Utilizing low doses of cangrelor with platelet function testing is an option during emergent neuroendovascular stenting and bridging. Cangrelor demonstrates significant variability in response at low doses and exhibits a dose response relationship when PFT is utilized.

Multipotential and systemic effects of traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of disability and mortality of people at all ages. Biochemical, cellular and physiological events that occur during primary injury lead to a delayed and long-term secondary damage that can last from hours to years. Secondary brain injury causes tissue damage in the central nervous system and a subsequent strong and rapid inflammatory response that may lead to persistent inflammation. However, this inflammatory response is not limited to the brain. Inflammatory mediators are transferred from damaged brain tissue to the bloodstream and produce a systemic inflammatory response in peripheral organs, including the cardiovascular, pulmonary, gastrointestinal, renal and endocrine systems. Complications of TBI are associated with its multiple and systemic effects that should be considered in the treatment of TBI patients. Therefore, in this review, an attempt was made to examine the systemic effects of TBI in detail. It is hoped that this review will identify the mechanisms of injury and complications of TBI, and open a window for promising treatment in TBI complications.

Platelet Receptor Activity for Predicting Survival in Patients with Intracranial Bleeding

Blood coagulation disorders in patients with intracranial bleeding as a result of head injuries or ruptured aneurysms are a diagnostic and therapeutic problem and appropriate assessments are needed to limit CNS damage and to implement preventive measures. The aim of the study was to monitor changes in platelet aggregation and to assess the importance of platelet dysfunction for predicting survival. Platelet receptor function analysis was performed using the agonists arachidonic acid (ASPI), adenosine diphosphate (ADP), collagen (COL), thrombin receptor activating protein (TRAP), ristocetin (RISTO) upon admission to the ICU and on days 2, 3, and 5. On admission, the ASPI, ADP, COL, TRAP, and RISTO tests indicated there was reduced platelet aggregation, despite there being a normal platelet count. In ‘Non-survivors’, the platelet response to all agonists was suppressed throughout the study period, while in ‘Survivors’ it improved. Measuring platelet function in ICU patients with intracranial bleeding is a strong predictor related to outcome: patients with impaired platelet aggregation had a lower 28-day survival rate compared to patients with normal platelet aggregation (log-rank test p = 0.014). The results indicated that measuring platelet aggregation can be helpful in the early detection, diagnosis, and treatment of bleeding disorders.

Prospective Analysis of Coagulopathy Associated with Isolated Traumatic Brain Injury and Clinical Outcome

Introduction Traumatic brain injury (TBI) affects the coagulation pathway in a distinct way than does extracranial trauma. The extent of coagulation abnormalities varies from bleeding diathesis to disseminated thrombosis.

Design Prospective study.

Methods The study included 50 patients of isolated TBI with cohorts of moderate (MHI) and severe head injury (SHI). Coagulopathy was graded according to the values of parameters in single laboratory. The incidence of coagulopathy according to the severity of TBI and correlation with disseminated intravascular coagulation (DIC) score, platelets, prothrombin time (PT), activated partial thromboplastin time (APTT), D-dimer, and fibrinogen was observed. The comparison was also made between expired and discharged patients within each group. It also compared coagulation derailments with clinical presentation (Glasgow Coma Scale [GCS]) and outcome (Glasgow Outcome Scale [GOS]).

Results Road traffic accident was the primary (72%) mode of injury. Fifty-two percent had MHI and rest had SHI. Eighty-four percent of cases were managed conservatively. The mean GCS was 12.23 and 5.75 in MHI and SHI, respectively. Sixty-two percent of MHI and 96% of the patients with SHI had coagulation abnormalities. On statistical analysis, DIC score (p < 0.001) strongly correlated with the severity of head injury and GOS. PT and APTT were also significantly associated with the severity of TBI. In patients with moderate TBI, D-dimer and platelet counts showed association with clinical outcome. Fibrinogen levels did not show any statistical significance. The mean platelet counts remained normal in both the groups of TBI. The mean GOS was 1.54 and 4.62 in SHI and MHI, respectively.

Conclusion Coagulopathy is common in isolated TBI. The basic laboratory parameters are reliable predictors of coagulation abnormalities in TBI. Coagulopathy is directly associated with the severity of TBI, GCS, and poor outcome.

Early Coagulopathy in Pediatric Traumatic Brain Injury: A Pediatric Acute and Critical Care Medicine Asian Network (PACCMAN) Retrospective Study

BACKGROUND

Although early coagulopathy increases mortality in adults with traumatic brain injury (TBI), less is known about pediatric TBI.

OBJECTIVE

To describe the prothrombin time (PT), activated partial thromboplastin time (APTT), and platelet levels of children with moderate to severe TBI to identify predictors of early coagulopathy and study the association with clinical outcomes.

METHODS

Using the Pediatric Acute and Critical Care Medicine Asian Network (PACCMAN) TBI retrospective cohort, we identified patients <16 yr old with a Glasgow Coma Scale (GCS) ≤13. We compared PT, APTT, platelets, and outcomes between children with isolated TBI and multiple trauma with TBI. We performed logistic regressions to identify predictors of early coagulopathy and study the association with mortality and poor functional outcomes.

RESULTS

Among 370 children analyzed, 53/370 (14.3%) died and 127/370 (34.3%) had poor functional outcomes. PT was commonly deranged in both isolated TBI (53/173, 30.6%) and multiple trauma (101/197, 51.3%). Predictors for early coagulopathy were young age (adjusted odds ratio [aOR] 0.94, 95% CI 0.88-0.99, P = .023), GCS < 8 (aOR 1.96, 95% CI 1.26-3.06, P = .003), and presence of multiple trauma (aOR 2.21, 95% confidence interval [CI] 1.37-3.60, P = .001). After adjusting for age, gender, GCS, multiple traumas, and presence of intracranial bleed, children with early coagulopathy were more likely to die (aOR 7.56, 95% CI 3.04-23.06, P < .001) and have poor functional outcomes (aOR 2.16, 95% CI 1.26-3.76, P = .006).

CONCLUSION

Early coagulopathy is common and independently associated with death and poor functional outcomes among children with TBI.

Alterations in platelet behavior after major trauma: adaptive or maladaptive?

Platelets are damage sentinels of the intravascular compartment, initiating and coordinating the primary response to tissue injury. Severe trauma and hemorrhage induce profound alterations in platelet behavior. During the acute post-injury phase, platelets develop a state of impaired ex vivo agonist responsiveness independent of platelet count, associated with systemic coagulopathy and mortality risk. In patients surviving the initial insult, platelets become hyper-responsive, associated with increased risk of thrombotic events. Beyond coagulation, platelets constitute part of a sterile inflammatory response to injury: both directly through release of immunomodulatory molecules, and indirectly through modifying behavior of innate leukocytes. Both procoagulant and proinflammatory aspects have implications for secondary organ injury and multiple-organ dysfunction syndromes. This review details our current understanding of adaptive and maladaptive alterations in platelet biology induced by severe trauma, mechanisms underlying these alterations, potential platelet-focused therapies, and existing knowledge gaps and their research implications.

Differential Leukocyte and Platelet Profiles in Distinct Models of Traumatic Brain Injury

Traumatic brain injury (TBI) affects over 3 million individuals every year in the U.S. There is growing appreciation that TBI can produce systemic modifications, which are in part propagated through blood–brain barrier (BBB) dysfunction and blood–brain cell interactions. As such, platelets and leukocytes contribute to mechanisms of thromboinflammation after TBI. While these mechanisms have been investigated in experimental models of contusion brain injury, less is known regarding acute alterations following mild closed head injury. To investigate the role of platelet dynamics and bioenergetics after TBI, we employed two distinct, well-established models of TBI in mice: the controlled cortical impact (CCI) model of contusion brain injury and the closed head injury (CHI) model of mild diffuse brain injury. Hematology parameters, platelet-neutrophil aggregation, and platelet respirometry were assessed acutely after injury. CCI resulted in an early drop in blood leukocyte counts, while CHI increased blood leukocyte counts early after injury. Platelet-neutrophil aggregation was altered acutely after CCI compared to sham. Furthermore, platelet bioenergetic coupling efficiency was transiently reduced at 6 h and increased at 24 h post-CCI. After CHI, oxidative phosphorylation in intact platelets was reduced at 6 h and increased at 24 h compared to sham. Taken together, these data demonstrate that brain trauma initiates alterations in platelet-leukocyte dynamics and platelet metabolism, which may be time- and injury-dependent, providing evidence that platelets carry a peripheral signature of brain injury. The unique trend of platelet bioenergetics after two distinct types of TBI suggests the potential for utilization in prognosis.

Platelet Dysfunction after Traumatic Brain Injury: A Review

Coagulopathy is a known sequela of traumatic brain injury (TBI) and can lead to increased morbidity and mortality. Platelet dysfunction has been identified as one of several etiologies of coagulopathy following TBI and has been associated with poor outcomes. Regardless of whether the platelet dysfunction occurs as a direct consequence of the injury or because of pre-existing medical comorbidities or medication use, accurate detection and monitoring of response to therapy is key to optimal patient care. Platelet transfusion has been proposed as a potential therapeutic intervention to treat platelet dysfunction, with several studies using platelet function assays to monitor response. The development of increasingly precise diagnostic testing is providing enhanced understanding of the specific derangement in the hemostatic process, allowing clinicians to provide patient-specific treatment plans. There is wide variability in the currently available literature on the incidence and clinical significance of platelet dysfunction following TBI, which creates challenges with developing evidence-based management guidelines. The relatively high prevalence of platelet inhibitor therapy serves as an additional confounding factor. In addition, the data are largely retrospective in nature. We performed a literature review to provide clarity on this clinical issue. We reviewed 348 abstracts, and included 97 manuscripts in our final literature review. Based on the currently available research, platelet dysfunction has been consistently demonstrated in patients with moderate-severe TBI. We recommend the use of platelet functional assays to evaluate patients with TBI. Platelet transfusion directed at platelet dysfunction may lead to improved clinical outcome. A randomized trial guided by implementation science could improve the applicability of these practices.

Does the Degree of Platelet Adenosine Diphosphate and Arachidonic Acid Receptor Inhibition Correlate With the Severity of Injury in Non-Brain-Injured Trauma Patients?

BACKGROUND

Direct correlations between platelet adenosine diphosphate (ADP) and arachidonic acid (AA) receptor inhibition have been described in the traumatic brain injury (TBI) population. Our goal was to evaluate the percent inhibition of ADP receptor inhibition (ADPri) and AA receptor inhibition (AAri) receptors in non-TBI patients and correlate injury severity and outcomes.

METHODS

We performed a retrospective review of non-TBI patients admitted to our trauma center, who received thromboelastography with platelet mapping prior to blood transfusion. Exclusion criteria included patients younger than 18 years, current antiplatelet therapy, or history of renal failure. Univariate descriptive statistics and bivariate comparisons were performed on patient demographic and outcomes. Multivariable linear regression models were constructed to quantify any association between ADPri and AAri with injury outcomes. High ADP inhibition was defined >20% and high AA inhibition >7%.

RESULTS

117 patients met inclusion criteria. Mean age was 53 years with 61% male. Mean ADPri was 64% and AAri 42%. On bivariate analysis, no statistically significant differences with respect to injury severity measures or outcomes were identified. On multivariable linear regression, AAri was associated with longer hospital length of stay.

DISCUSSION

There was a high degree of platelet dysfunction in this cohort of severely injured patients without TBI. Despite this, the only correlation identified between injury severity and outcomes was AAri correlating with hospital length of stay. Irrespective of injury severity or outcomes, these patients' results were far from reported "normal" values. Further, research is needed to determine the significance and clinical implications of thromboelastography with platelet mapping use in trauma care.

Computed tomographic parameters correlate with coagulation disorders in isolated traumatic brain injury

BACKGROUND AND OBJECTIVE

The imbalanced hemostatic equilibrium caused by brain tissue or vessel damage underlies the pathophysiology of traumatic brain injury (TBI)-induced coagulopathy, and cranial computed tomography (CT) is the gold standard for evaluating brain injury. The present study aimed to explore the correlation between quantitative cranial CT parameters and coagulopathy after TBI.

METHODS

We retrospectively collected the medical records of TBI patients with extracranial abbreviated injury scale (AIS) scores <3 who were admitted to our institution. The quantitative cranial CT parameters of patients with and without coagulopathy were compared, and univariate correlation analysis between CT parameters and coagulation subtest values and platelet counts was performed. The predictors for each subtest of coagulation function were probed by multivariate regression.

RESULTS

TBI patients with coagulopathy had a larger intracerebral haematoma/contusion (ICH/C) volume (p < 0.001), a higher incidence of compressed basal cisterns (p = 0.015), a higher Graeb score (p < 0.001) and subarachnoid haematoma (Fisher's scaling score) (p = 0.019) than those without coagulopathy. IH/C volume was identified as an independent risk factor for predicting coagulopathy. ICH/C volume showed a significantly positive correlation with APTT (Pearson's correlation = 0.333, p < 0.001), while a significant negative correlation with PLT (Pearson's correlation = - 0.312, p < 0.001).

CONCLUSION

ICH/C volume was a main quantitative cranial CT parameter for predicting coagulopathy, suggesting that parenchymal brain damage and vessel injury were closely associated with coagulopathy after TBI.

A journey upstream: Fluctuating platelet-specific genes in cell-free plasma as proof-of-concept for using ribonucleic acid sequencing to improve understanding of postinjury platelet biology

BACKGROUND

The mechanisms of aberrant circulating platelet behavior following injury remain unclear. Platelets retain megakaryocyte immature ribonucleic acid (RNA) splicing and protein synthesis machinery to alter their functions based on physiologic signals. We sought to identify fluctuating platelet-specific RNA transcripts in cell-free plasma (CFP) from traumatic brain injury (TBI) patients as proof-of-concept for using RNA sequencing to improve our understanding of postinjury platelet behavior. We hypothesized that we could identify differential expression of activated platelet-specific spliced RNA transcripts from CFP of patients with isolated severe fatal TBI (fTBI) compared with minimally injured trauma controls (t-controls), filtered by healthy control (h-control) data sets.

METHODS

High-read depth RNA sequencing was applied to CFP from 10 patients with fTBI (Abbreviated Injury Scale [AIS] for head ≥3, AIS for all other categories <3, and expired) and five t-controls (Injury Severity Score ≤1, and survived). A publicly available CFP RNA sequencing data set from 23 h-controls was used to determine the relative steady state of splice-form RNA transcripts discoverable in CFP. Activated platelet-specific spliced RNA transcripts were derived from studies of ex vivo platelet activation and identified by splice junction presence greater than 1.5-fold or less than 0.67-fold ex vivo nonactivated platelet-specific RNA transcripts.

RESULTS

Forty-two differentially spliced activated platelet-specific RNA transcripts in 34 genes were altered in CFP from fTBI patients (both upregulated and downregulated).

CONCLUSION

We have discovered differentially expressed activated platelet-specific spliced RNA transcripts present in CFP from isolated severe fTBI patients that are upregulated or downregulated compared with minimally injured trauma controls. This proof-of-concept suggests that a pool of immature platelet RNAs undergo splicing events after injury for presumed modulation of platelet protein products involved in platelet function. This validates our exploration of injury-induced platelet RNA transcript modulation as an upstream "liquid biopsy" to identify novel postinjury platelet biology and treatment targets for aberrant platelet behavior.

LEVEL OF EVIDENCE

Diagnostic tests, level V.

New Uses for Thromboelastography and Other Forms of Viscoelastic Monitoring in the Emergency Department: A Narrative Review

Patients frequently visit the emergency department with conditions that place them at risk of worse outcomes when accompanied by coagulopathy. Routine tests of coagulation-prothrombin time, partial thromboplastin time, platelets, and fibrinogen-have shortcomings that limit their use in providing emergency care. One alternative is to investigate coagulation disturbance with viscoelastic monitoring (VEM), a coagulation test that measures the timing and strength of blood clot development in real time. VEM is widely used and studied in cardiac surgery, liver transplant surgery, anesthesia, and trauma. In this article, we review the technique of VEM and the biologic rationale of using it in addition to routine tests of coagulation in emergency clinical situations. Then, we review the evidence (or lack thereof) for using VEM in the diagnosis and treatment of specific conditions. Finally, we describe the limitations of the test and future directions for clinical use and research in emergency medicine.

Platelet Function Analysis by Flowcytometry in Thrombocytopenic Trauma Patients

Hemostasis is dependent on sufficient quantity and quality of circulating functional platelets. Platelet function in trauma patients with thrombocytopenia and its impact on the clinical outcome is not adequately explored. Whether platelet dysfunction has a role in the pathogenesis of acute traumatic coagulopathy needs to be studied. Blood samples were collected from 70 thrombocytopenic trauma patients before transfusing platelets and assessed for platelet activation and platelet aggregation using flowcytometry. Primary outcome was in-hospital mortality. Platelet dysfunction was identified in 57.1% of thrombocytopenic trauma patients. A weak inverse correlation between percentage of activated platelets and APTT was observed (Spearman coefficient - 0.25, p = 0.03). A sensitivity and specificity of 66.6% was achieved for a cut off of ≤ 6.5% of platelet activation post trauma with ROC-AUC of 0.658 for identifying coagulopathy. No correlation with mortality however was observed (p > 0.05). Platelet dysfunction had a weak association with coagulopathy suggesting limited contribution of platelet dysfunction in pathogenesis of acute traumatic coagulopathy and warrants further research.

Identification of injury and shock driven effects on ex vivo platelet aggregometry: A cautionary tale of phenotyping

BACKGROUND

Platelet behavior in trauma-induced coagulopathy is poorly understood. Injured patients have impaired platelet aggregation (dysfunction) in ex vivo agonist-stimulated platelet aggregometry (PA). However, PA assumes that platelets are inactivated before ex vivo stimulated aggregation, which may be altered by injury. We hypothesized that following trauma, platelet aggregation (area under the curve) is decreased regardless of injury burden, but that (1) minor injury is associated with an increased baseline electrical impedance, characteristic of a functional platelet phenotype (platelets that activate in response to injury), and that (2) severe injury is not associated with an increased baseline electrical impedance, characteristic of a dysfunctional phenotype (platelets that do not activate well in response to injury) compared with healthy controls.

METHODS

Blood from 458 trauma patients and 30 healthy donors was collected for PA. Baseline electrical impedance (Ω); platelet aggregation stimulated by adenosine diphosphate, collagen, thrombin, and arachidonic acid; and rotational thromboelastometry were measured. Multivariate regression was performed to identify associations of PA measures with blood transfusion.

RESULTS

Compared with healthy controls, injured patients had impaired platelet aggregation in response to ex vivo stimulation, regardless of injury burden. However, minorly injured patients had increased endogenous platelet activation (baseline electrical impedance, Ω: with shock, p = 0.012; without shock, p = 0.084), but severely injured patients did not have significant increases in endogenous platelet activation (baseline electrical impedance, Ω: with shock, p = 0.86; without shock, p = 0.37). For every 10 Ω increase in baseline electrical impedance, there was an 8% decrease in units of blood transfused in the first 24 h (-0.08; confidence interval, -0.14 to -0.02; p = 0.015).

CONCLUSION

Injury and shock confer differential patterns of platelet aggregation in PA. Minor injury overestimates the presence of platelet dysfunction, while severe injury induces a truly dysfunctional phenotype-platelets that do not activate nor aggregate appropriately after injury. This is consequential in improving accurate phenotyping of postinjury platelet behavior for platelet-based therapeutics.

LEVEL OF EVIDENCE

Prognostic, level IV.

Effect of Chronic Alcoholism on Traumatic Intracranial Hemorrhage

BACKGROUND

Traumatic intracranial hemorrhage (TICH) is one of the commonest indications for neurosurgical consultation after trauma. Worsening neurologic examination results, size of initial TICH, presence of displaced skull fracture, and concomitant anticoagulant use at the time of injury drive the recommendations for repeat computed tomography of head (RCTH), to assess for stability of intracranial hemorrhage. Chronic alcohol use is not generally considered an indication for repeat head computed tomography (CT).

METHODS

A retrospective study of 423 patients with TICH with normal admission platelet (PLT) counts was reviewed for this study, taken as a subset of 1330 patients with TICH admitted to Lahey Hospital and Medical Center over a 3-year period. Of these 423 patients, 330 were classified as nonalcoholics and 93 were classified as alcoholics, based on whether alcohol use disorder was documented in the patient's medical record, present before injury. The normal PLT level was defined as ≥100,000 μ/L. Patients were excluded from review if they had comorbid conditions that could cause PLT dysfunction or coagulopathy. Continuous and categorical variables were compared using independent t test and χ², respectively. Binary logistic regression was used to predict outcome: stable versus worsening of TICH on RCTH. Statistical analysis was conducted using SPSS version 25.

RESULTS

The mean age of the nonalcoholic and alcoholic cohorts were 71.9 years and 54.8 years, respectively. A significantly higher percentage of alcoholics were male. There was a statistically significant difference (χ² = 8.14; P < 0.004) in radiologic progression of TICH between the 2 groups, with the alcoholics having a worsening RCTH 16.1% of the time compared with only 6.7% in nonalcoholics. Chronic alcohol use was an independent predictor of radiologic progression in patients with normal PLT level (odds ratio, 2.69; confidence interval, 1.34-5.43; P < 0.006).

CONCLUSIONS

Chronic alcohol use was an independent predictor of radiologic progression of TICH in the setting of normal PLT level. Modification of this risk of progression with transfusion of fresh PLTs in chronic alcoholic patients with TICH needs to be investigated in a prospective trial.

Bloodletting Puncture at Hand Twelve Jing-Well Points Improves Neurological Recovery by Ameliorating Acute Traumatic Brain Injury-Induced Coagulopathy in Mice

Traumatic brain injury (TBI) contributes to hypocoagulopathy associated with prolonged bleeding and hemorrhagic progression. Bloodletting puncture therapy at hand twelve Jing-well points (BL-HTWP) has been applied as a first aid measure in various emergent neurological diseases, but the detailed mechanisms of the modulation between the central nervous system and systemic circulation after acute TBI in rodents remain unclear. To investigate whether BL-HTWP stimulation modulates hypocoagulable state and exerts neuroprotective effect, experimental TBI model of mice was produced by the controlled cortical impactor (CCI), and treatment with BL-HTWP was immediately made after CCI. Then, the effects of BL-HTWP on the neurological function, cerebral perfusion state, coagulable state, and cerebrovascular histopathology post-acute TBI were determined, respectively. Results showed that BL-HTWP treatment attenuated cerebral hypoperfusion and improve neurological recovery post-acute TBI. Furthermore, BL-HTWP stimulation reversed acute TBI-induced hypocoagulable state, reduced vasogenic edema and cytotoxic edema by regulating multiple hallmarks of coagulopathy in TBI. Therefore, we conclude for the first time that hypocoagulopathic state occurs after acute experimental TBI, and the neuroprotective effect of BL-HTWP relies on, at least in part, the modulation of hypocoagulable state. BL-HTWP therapy may be a promising strategy for acute severe TBI in the future.

Microvesicles generated following traumatic brain injury induce platelet dysfunction via adenosine diphosphate receptor

BACKGROUND

Traumatic brain injury (TBI) can result in an acute coagulopathy including platelet dysfunction that can contribute to ongoing intracranial hemorrhage. Previous studies have shown adenosine diphosphate (ADP)-induced platelet aggregation to be reduced after TBI. In addition, circulating microvesicles (MVs) are increased following TBI and have been shown to play a role in post-TBI coagulopathy and platelet function. We hypothesized that post-TBI MVs would affect platelet aggregation in a murine head injury model.

METHODS

Moderate TBI was performed using a weight-drop method in male C57BL6 mice. Whole blood, plasma, MVs, and MV-poor plasma were isolated from blood collected 10 minutes following TBI and were mixed separately with whole blood from uninjured mice. Platelet aggregation was measured with Multiplate impedance platelet aggregometry in response to ADP. The ADP P2Y12 receptor inhibitor, R-138727, was incubated with plasma and MVs from TBI mice, and platelet inhibition was again measured.

RESULTS

Whole blood taken from 10-minute post-TBI mice demonstrated diminished ADP-induced platelet aggregation compared with sham mice. When mixed with normal donor blood, post-TBI plasma and MVs induced diminished ADP-induced platelet aggregation compared with sham plasma and sham MVs. By contrast, the addition of post-TBI MV-poor plasma to normal blood did not change ADP-induced platelet aggregation. The observed dysfunction in post-TBI ADP platelet aggregation was prevented by the pretreatment of post-TBI plasma with R-138727. Treatment of post-TBI MVs with R-138727 resulted in similar findings of improved ADP-induced platelet aggregation compared with nontreated post-TBI MVs.

CONCLUSION

Adenosine diphosphate-induced platelet aggregation is inhibited acutely following TBI in a murine model. This platelet inhibition is reproduced in normal blood by the introduction of post-TBI plasma and MVs. Furthermore, observed platelet dysfunction is prevented when post-TBI plasma and MVs are treated with an inhibitor of the P2Y12 ADP receptor. Clinically observed post-TBI platelet dysfunction may therefore be partially explained by the presence of the ADP P2Y12 receptor within post-TBI MVs.

LEVEL OF EVIDENCE

Level III.

Expert consensus on the diagnosis and treatment of thrombocytopenia in adult critical care patients in China

Thrombocytopenia is a common complication of critical care patients. The rates of bleeding events and mortality are also significantly increased in critical care patients with thrombocytopenia. Therefore, the Critical Care Medicine Committee of Chinese People's Liberation Army (PLA) worked with Chinese Society of Laboratory Medicine, Chinese Medical Association to develop this consensus to provide guidance for clinical practice. The consensus includes five sections and 27 items: the definition of thrombocytopenia, etiology and pathophysiology, diagnosis and differential diagnosis, treatment and prevention.

Ability of Fibrin Monomers to Predict Progressive Hemorrhagic Injury in Patients with Severe Traumatic Brain Injury

BACKGROUND

Progressive hemorrhagic injury (PHI) is common in patients with severe traumatic brain injury (TBI) and is associated with poor outcomes. TBI-associated coagulopathy is frequent and has been described as risk factor for PHI. This coagulopathy is a dynamic process involving hypercoagulable and hypocoagulable states either one after the other either concomitant. Fibrin monomers (FMs) are a direct marker of thrombin action and thus reflect coagulation activation. This study sought to determine the ability of FM to predict PHI after severe TBI.

METHODS

We conducted a prospective, observational study including all severe TBI patients admitted in the trauma center. Between September 2011 and September 2016, we enrolled patients with severe TBI into the derivation cohort. Between October 2016 and December 2018, we recruited the validation cohort on the same basis. Study protocol included FM measurements and standard coagulation test at admission and two computed tomography (CT) scans (upon arrival and at least 6 h thereafter). A PHI was defined by an increment in size of initial lesion (25% or more) or the development of a new hemorrhage in the follow-up CT scan. Multivariate logistic regression analysis was applied to identify predictors of PHI.

RESULTS

Overall, 106 patients were included in the derivation cohort. Fifty-four (50.9%) experienced PHI. FM values were higher in these patients (151 [136.8-151] vs. 120.5 [53.3-151], p < 0.0001). The ROC curve demonstrated that FM had a fair accuracy to predict the occurrence of PHI with an area under curve of 0.7 (95% CI [0.6-0.79]). The best threshold was determined at 131.7 μg/ml. In the validation cohort of 54 patients, this threshold had a negative predictive value of 94% (95% CI [71-100]) and a positive predictive value of 49% (95% CI [32-66]). The multivariate logistic regression analysis identified 2 parameters associated with PHI: FM ≥ 131.7 (OR 6.8; 95% CI [2.8-18.1]) and Marshall category (OR 1.7; 95% CI [1.3-2.2]). Coagulopathy was not associated with PHI (OR 1.3; 95% CI [0.5-3.0]). The proportion of patients with an unfavorable functional neurologic outcome at 6-months follow-up was higher in patients with positive FM: 59 (62.1%) versus 16 (29.1%), p < 0.0001.

CONCLUSIONS

FM levels at admission had a fair accuracy to predict PHI in patients with severe TBI. FM values ≥ 131.7 μg/ml are independently associated with the occurrence of PHI.

It's About Time: Transfusion effects on postinjury platelet aggregation over time

BACKGROUND

Impaired postinjury platelet aggregation is common, but the effect of transfusion on this remains unclear. Data suggest that following injury platelet transfusion may not correct impaired platelet aggregation, and impaired platelet aggregation may not predict the need for platelet transfusion. We sought to further investigate platelet aggregation responses to transfusions, using regression statistics to isolate the independent effects of transfusions given in discrete time intervals from injury on both immediate and longitudinal platelet aggregation. We hypothesized that platelet aggregation response to platelet transfusion increases over time from injury.

METHODS

Serial (0-96 hours) blood samples were collected from 248 trauma patients. Platelet aggregation was assessed in vitro with impedance aggregometry stimulated by adenosine diphosphate, collagen, and thrombin receptor-activating peptide-6. Using regression, transfusion exposure was modeled against platelet aggregation at each subsequent timepoint and adjusted for confounders (Injury Severity Score, international normalized ratio (INR), base deficit, platelet count, and interval transfusions). The expected change in platelet aggregation at each timepoint under the intervention of transfusion exposure was calculated and compared with the observed platelet aggregation.

RESULTS

The 248 patients analyzed were severely injured (Injury Severity Score, 21 ± 19), with normal platelet counts (mean, 268 × 10/L ± 90), and 62% were transfused in 24 hours. The independent effect of transfusions on subsequent platelet aggregation over time was modeled with observed platelet aggregation under hypothetical treatment of one unit transfusion of blood, plasma, or platelets. Platelet transfusions had increasing expected effects on subsequent platelet aggregation over time, with the maximal expected effect occurring late (4-5 days from injury).

CONCLUSION

Controversy exists on whether transfusions improve impaired postinjury platelet aggregation. Using regression modeling, we identified that expected transfusion effects on subsequent platelet aggregation are maximal with platelet transfusion given late after injury. This is critical for tailored resuscitation, identifying a potential early period of resistance to platelet transfusion that resolves by 96 hours.

LEVEL OF EVIDENCE

Therapeutic, level V.

A Novel Platelet Function Assay for Trauma

BACKGROUND

Platelet function tests such as thrombelastography platelet mapping and impedance aggregometry have demonstrated universal platelet dysfunction in trauma patients. In this study, we introduce the measurement of platelet contraction force as a test of platelet function. We hypothesize that force will correlate with established coagulation tests such as thrombelastography, demonstrate significant differences between healthy subjects and trauma patients, and identify critically ill trauma patients.

METHODS

Blood samples were prospectively collected from level 1 trauma patients at initial presentation, assayed for force of and time to contraction and compared with thrombelastography. Blood from healthy subjects was assayed to establish a reference range. Results from trauma patients were compared with healthy controls and trauma patients that died.

RESULTS

The study includes one hundred trauma patients with mean age 45 y, 74% were male, and median injury severity score of 14 ± 12. Patients that survived (n = 90) demonstrated significantly elevated platelet contraction force compared with healthy controls (n = 12) (6390 ± 2340 versus 4790 ± 470 μN, P = 0.043) and trauma patients that died (n = 10) (6390 ± 2340 versus 2860 ± 1830 μN, P = 0.0001). Elapsed time to start of platelet contraction was faster in trauma patients that survived compared with healthy controls (660 ± 467 versus 1130 ± 140 s, P = 0.0022) and those that died (660 ± 470 versus 1460 ± 1340 s, P < 0.0001).

CONCLUSIONS

In contrast with all existing platelet function tests reported in the literature, which report platelet dysfunction in trauma patients, contractile force demonstrates hyperfunction in surviving trauma patients and dysfunction in nonsurvivors. Platelet contraction reflects platelet metabolic reserve and thus may be a potential biomarker for survival after trauma. Contractile force warrants further investigation to predict mortality in severely injured trauma patients.

Platelet Function Changes in a Time-Dependent Manner Following Traumatic Brain Injury in a Murine Model

Traumatic brain injury (TBI) results in systemic changes in coagulation and inflammation that contribute to post-traumatic morbidity and mortality. The potential interaction of platelets and pro-inflammatory cytokines in the modulation of coagulation, microthrombosis, and venous thromboembolic events after moderate TBI has not been determined. Using a murine model, we hypothesized that the degree of platelet-induced coagulation varies depending on the platelet aggregation agonist platelet-induced coagulation changes in a time-dependent manner following TBI, and changes in platelet-induced coagulation are mirrored by changes in the levels of circulating pro-inflammatory cytokines. An established weight-drop model was used to induce TBI in anesthetized mice. Blood samples were collected at intervals after injury for measurements of platelet count, serum fibrinogen, pro-inflammatory cytokines, and determination of soluble P-selectin levels. Thromboelastometry was used to evaluate changes in hemostasis. Platelet function was determined using whole blood impedance aggregometry. Ten minutes following TBI, adenosine diphosphate-induced platelet aggregation decreased as measured by platelet aggregometry. Despite no changes in platelet counts and serum fibrinogen, platelet aggregation, pro-inflammatory cytokines, and soluble P-selectin were increased at 6 h after TBI. Rotation thromboelastometry demonstrated increased maximal clot firmness at 6 h. Platelet function and coagulability returned to baseline levels 24 h following head injury. Our data demonstrate that after TBI, acute platelet dysfunction occurs followed by rebound platelet hyperaggregation. Alterations in post-TBI platelet aggregation are reflected in whole blood thromboelastometry and are temporally associated with the systemic pro-inflammatory response.

Goal-directed platelet transfusions correct platelet dysfunction and may improve survival in patients with severe traumatic brain injury

BACKGROUND

Platelet dysfunction, defined as adenosine diphosphate inhibition greater than 60% on thromboelastogram, is an independent predictor of increased mortality in patients with severe traumatic brain injury (TBI). We changed our practice to transfuse platelets for all patients with severe TBI and platelet dysfunction. We hypothesized that platelet transfusions would correct platelet dysfunction and improve mortality in patients with severe TBI.

METHODS

This retrospective review included adult trauma patients admitted to our Level I trauma center from July 2015 to October 2016 with severe TBI (head Abbreviated Injury Scale score ≥ 3) who presented with platelet dysfunction and subsequently received a platelet transfusion. Serial thromboelastograms were obtained to characterize the impact of platelet transfusion on clot strength. Subsequently, the platelet transfusion group was compared to a group of historical controls with severe TBI patients and platelet dysfunction who did not receive platelet transfusion.

RESULTS

A total of 35 patients with severe TBI presented with platelet dysfunction. Following platelet transfusion clot strength improved as represented by decreased K time, increased α angle, maximum amplitude, and G-value, as well as correction of adenosine diphosphate inhibition. When comparing to 51 historic controls with severe TBI and platelet dysfunction, the 35 study patients who received a platelet transfusion had a lower mortality (9% vs. 35%; p = 0.005). In stepwise logistic regression, platelet transfusion was independently associated with decreased mortality (odds ratio, 0.23; 95% confidence interval, 0.06-0.92; p = 0.038).

CONCLUSION

In patients with severe TBI and platelet dysfunction, platelet transfusions correct platelet inhibition and may be associated with decreased mortality.

LEVEL OF EVIDENCE

Therapeutic, level II.