Pathophysiology of Coagulopathy Induced by Traumatic Brain Injury Is Identical to That of Disseminated Intravascular Coagulation With Hyperfibrinolysis

Phenotypes of Disseminated Intravascular Coagulation

Two phenotypes of disseminated intravascular coagulation (DIC) are systematically reviewed. DIC is classified into thrombotic and fibrinolytic phenotypes characterized by thrombosis and hemorrhage, respectively. Major pathology of DIC with thrombotic phenotype is the activation of coagulation, insufficient anticoagulation with endothelial injury, and plasminogen activator inhibitor-1-mediated inhibition of fibrinolysis, leading to microvascular fibrin thrombosis and organ dysfunction. DIC with fibrinolytic phenotype is defined as massive thrombin generation commonly observed in any type of DIC, combined with systemic pathologic hyperfibrinogenolysis caused by underlying disorder that results in severe bleeding due to excessive plasmin formation. Three major pathomechanisms of systemic hyperfibrinogenolysis have been considered: (1) acceleration of tissue-type plasminogen activator (t-PA) release from hypoxic endothelial cells and t-PA-rich storage pools, (2) enhancement of the conversion of plasminogen to plasmin due to specific proteins and receptors that are expressed on cancer cells and endothelial cells, and (3) alternative pathways of fibrinolysis. DIC with fibrinolytic phenotype can be diagnosed by DIC diagnosis followed by the recognition of systemic pathologic hyperfibrin(ogen)olysis. Low fibrinogen levels, high fibrinogen and fibrin degradation products (FDPs), and the FDP/D-dimer ratio are important for the diagnosis of systemic pathologic hyperfibrin(ogen)olysis. Currently, evidence-based treatment strategies for DIC with fibrinolytic phenotypes are lacking. Tranexamic acid appears to be one of the few methods to be effective in the treatment of systemic pathologic hyperfibrin(ogen)olysis. International cooperation for the elucidation of pathomechanisms, establishment of diagnostic criteria, and treatment strategies for DIC with fibrinolytic phenotype are urgent issues in the field of thrombosis and hemostasis.

Effect of low fibrinogen level on in-hospital mortality and 6-month functional outcome of TBI patients, a single center experience

In patients affected by traumatic brain injury (TBI), hypofibrinogenemia within the initial hours of trauma can be expected due to vascular and inflammatory changes. In this study, we aimed to evaluate the effect of hypofibrinogenemia on the in-hospital mortality and 6-month functional outcomes of TBI patients, admitted to Rajaee Hospital, a referral trauma center in Shiraz, Iran. This study included all TBI patients admitted to our center who had no prior history of coagulopathy or any systemic disease, were alive on arrival, and had not received any blood product before admission. On admission, hospitalization, imaging, and 6-month follow-up information of included patients were extracted from the TBI registry database. The baseline characteristics of patients with fibrinogen levels of less than 150 mg/dL were compared with the cases with higher levels. To assess the effect of low fibrinogen levels on in-hospital mortality, a uni- and multivariate was conducted between those who died in hospital and survivors. Based on the 6-month GOSE score of patients, those with GOSE < 4 (unfavorable outcome) were compared with those with a favorable outcome. A total of 3049 patients (84.3% male, 15.7% female), with a mean age of 39.25 ± 18.87, met the eligibility criteria of this study. 494 patients had fibrinogen levels < 150 mg/dl, who were mostly younger and had lower average GCS scores in comparison to cases with higher fibrinogen levels. By comparison of the patients who died during hospitalization and survivors, it was shown that fibrinogen < 150 mg/dl is among the prognostic factors for in-hospital mortality (OR:1.75, CI: 1.32:2.34, P-value < 0.001), while the comparison between patients with the favorable and unfavorable functional outcome at 6-month follow-up, was not in favor of prognostic effect of low fibrinogen level (OR: 0.80, CI: 0.58: 1.11, P-value: 0.19). Hypofibrinogenemia is associated with in-hospital mortality of TBI patients, along with known factors such as higher age and lower initial GCS score. However, it is not among the prognostic factors of midterm functional outcome.

Roles and therapeutic potential of different extracellular vesicle subtypes on traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of injury-related disability and death around the world, but the clinical stratification, diagnosis, and treatment of complex TBI are limited. Due to their unique properties, extracellular vesicles (EVs) are emerging candidates for being biomarkers of traumatic brain injury as well as serving as potential therapeutic targets. However, the effects of different extracellular vesicle subtypes on the pathophysiology of traumatic brain injury are very different, or potentially even opposite. Before extracellular vesicles can be used as targets for TBI therapy, it is necessary to classify different extracellular vesicle subtypes according to their functions to clarify different strategies for EV-based TBI therapy. The purpose of this review is to discuss contradictory effects of different EV subtypes on TBI, and to propose treatment ideas based on different EV subtypes to maximize their benefits for the recovery of TBI patients. Video Abstract.

Traumatic Brain Injury: Intraoperative Management and Intensive Care Unit Multimodality Monitoring

Traumatic brain injury is a devastating event associated with substantial morbidity. Pathophysiology involves the initial trauma, subsequent inflammatory response, and secondary insults, which worsen brain injury severity. Management entails cardiopulmonary stabilization and diagnostic imaging with targeted interventions, such as decompressive hemicraniectomy, intracranial monitors or drains, and pharmacological agents to reduce intracranial pressure. Anesthesia and intensive care requires control of multiple physiologic variables and evidence-based practices to reduce secondary brain injury. Advances in biomedical engineering have enhanced assessments of cerebral oxygenation, pressure, metabolism, blood flow, and autoregulation. Many centers employ multimodality neuromonitoring for targeted therapies with the hope to improve recovery.

Gender-related differences in the coagulofibrinolytic responses and long-term outcomes in patients with isolated traumatic brain injury: A 2-center retrospective study

Coagulation function differs by gender, with women being characterized as more hypercoagulable. Even in the early stages of trauma, women have been shown to be hypercoagulable. Several studies have also examined the relationship between gender and the prognosis of trauma patients, but no certain conclusions have been reached. Patients with isolated traumatic brain injury (iTBI) are known to have coagulopathy, but no previous studies have examined the gender differences in detail. This is a retrospective analysis of a prospective registry conducted at 2 centers. The study included adult patients with iTBI enrolled from April 2018 to March 2021. Coagulofibrinolytic markers were measured in each patient at 1 hour, 24 hours, 3 days, and 7 days after injury, and neurological outcomes were assessed with the Glasgow Outcome Scale Extended at 6 months. Subgroup analysis was also performed by categorizing patients into groups according to neurological prognosis or age at 50 years. Males (n = 31) and females (n = 21) were included in the analysis. In males, there was a significant difference in the levels of activated partial thromboplastin time (P = .007), fibrin/fibrinogen degradation products (P = .025), D-dimer (P = .034), α2-plasmin inhibitor (P = .030), plasmin-α2-plasmin inhibitor complex (P = .004) at 1 hour after injury between favorable and unfavorable long-term neurological outcome groups, while in females there was no significant difference in these markers between 2 groups. In the age group under 50 years, there were significant gender differences in fibrinogen (day 3: P = .018), fibrin/fibrinogen degradation products (1 hour: P = .037, day 3: P = .009, day 7: P = .037), D-dimer (day 3: P = .005, day 7: P = .010), plasminogen (day 3: P = .032, day 7: P = .032), and plasmin-α2-plasmin inhibitor complex (day 3: P = .001, day 7: P = .001), and these differences were not evident in the age group over 50 years. There were differences in coagulofibrinolytic markers depending on gender in patients with iTBI. In male patients, aggravation of coagulofibrinolytic markers immediately after traumatic brain injury may be associated with poor neurologic outcome 6 months after injury.

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.

Association of antithrombin with development of trauma-induced disseminated intravascular coagulation and outcomes

Introduction

Trauma activates the innate immune system to modulate hemostasis and minimize the damage caused by physiological bodily responses, including the activation of coagulation. Sufficiently severe trauma overwhelms physiological responses and elicits the systemic inflammatory response syndrome, which leads to the onset of disseminated intravascular coagulation (DIC), characterized by dysregulated inflammatory coagulofibrinolytic responses. Impaired anticoagulant mechanisms, including antithrombin, constitutes the pathology of DIC, while the dynamics of antithrombin and relevance to outcomes in trauma-induced coagulopathy have not been fully elucidated. This study investigated the associations of antithrombin activity with DIC onset and outcomes in severely injured patients.

Methods

This retrospective sub-analysis of a multicenter, prospective study included patients with an injury severity score ≥16. We characterized trauma patients with low antithrombin activity (antithrombin <80% on hospital arrival, n = 75) in comparison with those who had normal antithrombin activity (antithrombin ≥80%, n = 200). Global markers of coagulation and fibrinolysis, molecular biomarkers for thrombin generation (soluble fibrin [SF]), and markers of anticoagulation (antithrombin) were evaluated to confirm the associations of antithrombin with DIC development and outcomes, including in-hospital mortality and the multiple organ dysfunction syndrome (MODS).

Results

Patients with low antithrombin activity had higher prevalence of shock, transfusion requirements, and in-hospital mortality. Higher DIC scores and more severe organ dysfunction were observed in the low AT group compared to that in the normal AT group. Antithrombin activity on arrival at the hospital was an independent predictor of the development of DIC in trauma patients, and levels of SF increased with lower antithrombin values (antithrombin activity > 85%). Antithrombin activity at 3 h showed good predictive performance for in-hospital mortality, and a multivariable Cox proportional-hazard regression model with a cross-product term between the antithrombin and DIC showed that the in-hospital mortality in patients with DIC increased with decreased antithrombin activity. A multivariable logistic regression model showed that the odds for the development of MODS in patients with DIC increased with lower antithrombin values.

Conclusion

Decreased antithrombin activity in trauma-induced coagulopathy is associated with poor outcomes through worsening of DIC.

Hyperfibrinolysis and fibrinolysis shutdown in patients with traumatic brain injury

Traumatic brain injury (TBI) is associated with coagulation/fibrinolysis disorders. We retrospectively evaluated 61 TBI cases transported to hospital within 1 h post-injury. Levels of thrombin-antithrombin III complex (TAT), D-dimer, and plasminogen activator inhibitor-1 (PAI-1) were measured on arrival and 3 h, 6 h, 12 h, 1 day, 3 days and 7 days after injury. Multivariate logistic regression analysis was performed to identify prognostic factors for coagulation and fibrinolysis. Plasma TAT levels peaked at admission and decreased until 1 day after injury. Plasma D-dimer levels increased, peaking up to 3 h after injury, and decreasing up to 3 days after injury. Plasma PAI-1 levels increased up to 3 h after injury, the upward trend continuing until 6 h after injury, followed by a decrease until 3 days after injury. TAT, D-dimer, and PAI-1 were elevated in the acute phase of TBI in cases with poor outcome. Multivariate logistic regression analysis showed that D-dimer elevation from admission to 3 h after injury and PAI-1 elevation from 6 h to 1 day after injury were significant negative prognostic indicators. Post-TBI hypercoagulation, fibrinolysis, and fibrinolysis shutdown were activated consecutively. Hyperfibrinolysis immediately after injury and subsequent fibrinolysis shutdown were associated with poor outcome.

Neurovascular Unit-Derived Extracellular Vesicles: From Their Physiopathological Roles to Their Clinical Applications in Acute Brain Injuries

Extracellular vesicles (EVs) form a heterogeneous group of membrane-enclosed structures secreted by all cell types. EVs export encapsulated materials composed of proteins, lipids, and nucleic acids, making them a key mediator in cell–cell communication. In the context of the neurovascular unit (NVU), a tightly interacting multicellular brain complex, EVs play a role in intercellular communication and in maintaining NVU functionality. In addition, NVU-derived EVs can also impact peripheral tissues by crossing the blood–brain barrier (BBB) to reach the blood stream. As such, EVs have been shown to be involved in the physiopathology of numerous neurological diseases. The presence of NVU-released EVs in the systemic circulation offers an opportunity to discover new diagnostic and prognostic markers for those diseases. This review outlines the most recent studies reporting the role of NVU-derived EVs in physiological and pathological mechanisms of the NVU, focusing on neuroinflammation and neurodegenerative diseases. Then, the clinical application of EVs-containing molecules as biomarkers in acute brain injuries, such as stroke and traumatic brain injuries (TBI), is discussed.

Blood biomarkers for predicting coagulopathy occurrence in patients with traumatic brain injury: a systematic review

Purpose: The occurrence of coagulopathy in patients with traumatic brain injury (TBI) is related to severe complications. The authors performed the first systematic review to investigate whether biomarkers can predict the occurrence of hypocoagulopathy or progressive hemorrhagic injury in patients with TBI. Methods: The authors included studies that performed a receiver operating characteristics analysis for the biomarker and provided a clear value along with the respective sensitivity and specificity. Additionally, they attempted to classify each biomarker, taking into account its physiological role. Results: Twelve studies were included. All biomarkers were protein molecules, except in one study that examined the prognostic role of glucose. Copeptin had the highest sensitivity, and S100A12 had the highest specificity in predicting coagulopathy, while IL-33 had the highest sensitivity and GALECTIN-3 had the highest specificity in predicting progressive hemorrhagic injury. Conclusion: The study of the role of biomarkers in predicting the occurrence of coagulopathy in patients with TBI remains in its infancy.

Association of Histones With Coagulofibrinolytic Responses and Organ Dysfunction in Adult Post-cardiac Arrest Syndrome

Background

Patients successfully resuscitated from cardiac arrest often develop organ dysfunction caused by systemic inflammation and increased coagulation, leading to disseminated intravascular coagulation (DIC). The involvement of histones in DIC and organ dysfunction in patients with sepsis and trauma has been previously reported, raising the probability that histones may also be associated with pathophysiology in patients after cardiac arrest and resuscitation. This study evaluated the relationship between histones and organ dysfunction related to coagulofibrinolytic changes in patients with post-cardiac arrest syndrome (PCAS).

Methods

This prospective single-center observational study assessed 35 adult patients with PCAS who were divided into two groups, i.e., 15 patients with multiple organ dysfunction syndrome (MODS) and 20 patients without MODS. MODS was defined as a sequential organ failure assessment score of ≥12. The plasma levels of histones and coagulofibrinolytic markers, including soluble fibrin, tissue-type plasminogen activator, plasminogen activator inhibitor-1, plasmin-alpha 2-plasmin inhibitor complex (PIC), and soluble thrombomodulin, were measured in patients with PCAS immediately after admission to the emergency department, and 3 and 24 h after arriving at the hospital.

Results

PCAS patients with MODS had higher DIC scores [4 (3.0–5.0) vs. 1 (0.0–3.0), p = 0.012] and higher mortality rates (66.7% vs. 20.0%, p = 0.013) than those without MODS. Moreover, patients with MODS exhibited higher histone levels than those without MODS during the early phase of the post-resuscitation period. Severe endothelial injury and higher thrombin and plasmin generation were observed in the MODS group. Plasma levels of histones were positively correlated with those of soluble fibrin immediately after resuscitation (rho = 0.367, p = 0.030) and PIC 3 h after arriving at the hospital (rho = 0.480, p = 0.005). This correlation was prominent in the patient population with MODS (soluble fibrin: rho = 0.681, p = 0.005, PIC: rho = 0.742, p = 0.002).

Conclusions

This study demonstrated that elevated histone levels were associated with increased levels of thrombin, and subsequent plasmin generation in PCAS patients, especially those with MODS. Further studies are required to elucidate the causal relationship between histones and organ dysfunction related to DIC in PCAS.

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

Background: The incidence of coagulopathy after open traumatic brain injury (TBI) is high. Coagulopathy can aggravate intracranial hemorrhage and further increase morbidity and mortality. The purpose of this study was to determine the clinical characteristics of coagulopathy after open TBI and its relationship with the prognosis. Methods: This study retrospectively evaluated patients with isolated open TBI from December 2018 to December 2020. Coagulopathy was defined as international normalized ratio (INR) > 1.2, activated thromboplastin time (APTT) > 35 s, or platelet count <100,000/μL. We compared the relationship between the clinical, radiological, and laboratory parameters of patients with and without coagulopathy, and the outcome at discharge. Logistic regression analysis was used to evaluate the risk factors associated with coagulopathy. We then compared the effects of treatment with and without TXA in open TBI patients with coagulopathy. Results: A total of 132 patients were included in the study; 46 patients developed coagulopathy. Patients with coagulopathy had significantly lower platelet levels (170.5 × 10⁹/L vs. 216.5 × 10⁹/L, p < 0.001), and significantly higher INR (1.14 vs. 1.02, p < 0.001) and APTT (30.5 s vs. 24.5 s, p < 0.001) compared to those with no coagulopathy. A Low Glasgow Coma Scale (GCS) score, high neutrophil/lymphocyte ratio (NLR), low platelet/lymphocyte ratio (PLR), and hyperglycemia at admission were significantly associated with the occurrence of coagulopathy. Conclusions: Coagulopathy often occurs after open TBI. Patients with a low GCS score, high NLR, low PLR, and hyperglycemia at admission are at greater risk of coagulopathy, and therefore of poor prognosis. The efficacy of TXA in open TBI patients with coagulopathy is unclear. In addition, these findings demonstrate that PLR may be a novel indicator for predicting coagulopathy.