Coagulopathy associated with traumatic brain injury

The role of coagulopathy and subdural hematoma thickness at admission in predicting the prognoses of patients with severe traumatic brain injury: a multicenter retrospective cohort study from China

BACKGROUND

Traumatic brain injury (TBI) is one of the diseases with high disability and mortality worldwide. Recent studies have shown that TBI-related factors may change the complex balance between bleeding and thrombosis, leading to coagulation disorders. The aim of this retrospective study was to investigate the prediction of coagulopathy and subdural hematoma thickness at admission using the Glasgow Outcome Scale (GOS) in patients with severe TBI at 6 months after discharge.

METHODS

In this retrospective cohort study, a total of 1006 patients with severe TBI in large medical centers in three different provinces of China from June 2015 to June 2021 were enrolled after the exclusion criteria, and 800 patients who met the enrollment criteria were included. A receiver operating characteristic (ROC) curve was used to determine the best cut-off values of platelet (PLT), international normalized ratio (INR), activated partial thromboplastin time (APTT), and subdural hematoma (SDH) thickness. The ROC curve, nomogram, calibration curve, and the decision curve were used to evaluate the predictive effect of the coagulopathy and Coagulopathy-SDH(X1) models on the prognoses of patients with severe TBI, and the importance of predictive indicators was ranked by machine learning.

RESULTS

Among the patients with severe TBI on admission, 576/800 (72%) had coagulopathy, 494/800 (61%) had SDH thickness ≥14.05 mm, and 385/800 (48%) had coagulopathy combined with SDH thickness ≥14.05 mm. Multivariate logistic regression analyses showed that age, pupil, brain herniation, WBC, CRP, SDH, coagulopathy, and X1 were independent prognostic factors for GOS after severe TBI. Compared with other single indicators, X1 as a predictor of the prognosis of severe TBI was more accurate. The GOS of patients with coagulopathy and thick SDH (X1, 1 point) at 6 months after discharge was significantly worse than that of patients with coagulopathy and thin SDH (X1, 2 points), patients without coagulopathy and thick SDH (X1, 3 point), and patients without coagulopathy and thin SDH (X1, 4 points). In the training group, the C-index based on the coagulopathy nomogram was 0.900. The C-index of the X1-based nomogram was 0.912. In the validation group, the C-index based on the coagulopathy nomogram was 0.858. The C-index of the X1-based nomogram was 0.877. Decision curve analysis also confirmed that the X1-based model had a higher clinical net benefit of GOS at 6 months after discharge than the coagulopathy-based model in most cases, both in the training and validation groups. In addition, compared with the calibration curve based on the coagulopathy model, the prediction of the X1 model-based calibration curve for the probability of GOS at 6 months after discharge showed better agreement with actual observations. Machine learning compared the importance of each independent influencing factor in the evaluation of GOS prediction after TBI, with results showing that the importance of X1 was better than that of coagulopathy alone.

CONCLUSION

Coagulopathy combined with SDH thickness could be used as a new, accurate, and objective clinical predictor, and X1, based on combining coagulopathy with SDH thickness could be used to improve the accuracy of GOS prediction in patients with TBI, 6 months after discharge.

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.

Neutrophil extracellular traps contribute to coagulopathy after traumatic brain injury

Coagulopathy contributes to the majority of deaths and disabilities associated with traumatic brain injury (TBI). Whether neutrophil extracellular traps (NETs) contribute to an abnormal coagulation state in the acute phase of TBI remains unknown. Our objectives were to demonstrate the definitive role of NETs in coagulopathy in TBI. We detected NET markers in 128 TBI patients and 34 healthy individuals. Neutrophil-platelet aggregates were detected in blood samples from TBI patients and healthy individuals using flow cytometry and staining for CD41 and CD66b. Endothelial cells were incubated with isolated NETs and we detected the expression of vascular endothelial cadherin, syndecan-1, thrombomodulin, von Willebrand factor, phosphatidylserine, and tissue factor. In addition, we established a TBI mouse model to determine the potential role of NETs in TBI-associated coagulopathy. NET generation was mediated by high mobility group box 1 (HMGB1) from activated platelets and contributed to procoagulant activity in TBI. Furthermore, coculture experiments indicated that NETs damaged the endothelial barrier and caused these cells to assume a procoagulant phenotype. Moreover, the administration of DNase I before or after brain trauma markedly reduced coagulopathy and improved the survival and clinical outcome of mice with TBI.

Emergent surgical evacuation of traumatic intracranial hematoma in patients with preoperative thrombocytopenia: surgical risk and early outcome

BACKGROUND

Surgical evacuation of intracranial hematoma, including epidural, subdural, intracerebral, and intraventricular hematoma, is recommended in patients with traumatic brain injury (TBI) for prevention of cerebral herniation and possible saving of life. However, preoperative coagulopathy is a major concern for emergent surgery on patients with severe TBI.

METHODS

We reviewed 65 consecutive patients with severe TBI who underwent emergency craniotomy for intracranial hematomas.

RESULTS

Univariate analysis showed preoperative pupil abnormality, absence of pupil light reflex, respiratory failure, preoperative thrombocytopenia (< 100 × 10⁹/L), increased activated partial thromboplastin time (> 36 s), low fibrinogen (< 150 mg/dL), platelet transfusion, red cell concentrate transfusion, and presence of brain contusion and traumatic subarachnoid hemorrhage (SAH) on computed tomography were correlated with poor outcome (death or vegetative state). Multivariate analysis revealed that pupil abnormality (p = 0.001; odds ratio [OR] 0.064, 95% confidence interval [CI] 0.012-0.344), preoperative thrombocytopenia (p = 0.016; OR 0.101, 95% CI 0.016-0.656), and traumatic SAH (p = 0.021; OR 0.211, 95% CI 0.057-0.791) were significant factors. Investigation of the 14 patients with preoperative thrombocytopenia found the emergency surgery was successful, with no postoperative bleeding during hospitalization. However, half of the patients died, and almost a quarter remained in the vegetative state mainly associated with severe cerebral edema.

CONCLUSIONS

Emergent craniotomy for patients with severe TBI who have preoperative thrombocytopenia is often successful, but the prognosis is often poor. Emergency medical care teams and neurosurgeons should be aware of this discrepancy between successful surgery and poor prognosis in these patients. Further study may be needed on the cerebral edema regulator function of platelets.

PEGylated Polyester Nanoparticles Trigger Adverse Events in a Large Animal Model of Trauma and in Naı̈ve Animals: Understanding Cytokine and Cellular Correlations with These Events

Intravenously infusible nanoparticles to control bleeding have shown promise in rodents, but translation into preclinical models has been challenging as many of these nanoparticle approaches have resulted in infusion responses and adverse outcomes in large animal trauma models. We developed a hemostatic nanoparticle technology that was screened to avoid one component of the infusion response: complement activation. We administered these hemostatic nanoparticles, control nanoparticles, or saline volume controls in a porcine polytrauma model. While the hemostatic nanoparticles promoted clotting as marked by a decrease in prothrombin time and both the hemostatic nanoparticles and controls did not active complement, in a subset of the animals, hard thrombi were found in uninjured tissues in both the hemostatic and control nanoparticle groups. Using data science methods that allow one to work across heterogeneous data sets, we found that the presence of these thrombi correlated with changes in IL-6, INF-alpha, lymphocytes, and neutrophils. While these findings might suggest that this formulation would not be a safe one for translation for trauma, they provide guidance for developing screening tools to make nanoparticle formulations in the complex milieux of trauma as well as for therapeutic interventions more broadly. This is important as we look to translate intravenously administered nanoparticle formulations for therapies, particularly considering the vascular changes seen in a subset of patients following COVID-19. We need to understand adverse events like thrombi more completely and screen for these events early to make nanomaterials as safe and effective as possible.

The Role of Platelets in the Stimulation of Neuronal Synaptic Plasticity, Electric Activity, and Oxidative Phosphorylation: Possibilities for New Therapy of Neurodegenerative Diseases

The central nervous system (CNS) is highly vascularized where neuronal cells are located in proximity to endothelial cells, astroglial limitans, and neuronal processes constituting integrated neurovascular units. In contrast to many other organs, the CNS has a blood-brain barrier (BBB), which becomes compromised due to infection, neuroinflammation, neurodegeneration, traumatic brain injury, and other reasons. BBB disruption is presumably involved in neuronal injury during epilepsy and psychiatric disorders. Therefore, many types of neuropsychological disorders are accompanied by an increase in BBB permeability leading to direct contact of circulating blood cells in the capillaries with neuronal cells in the CNS. The second most abundant type of blood cells are platelets, which come after erythrocytes and outnumber ~100-fold circulating leukocytes. When BBB becomes compromised, platelets swiftly respond to the vascular injury and become engaged in thrombosis and hemostasis. However, more recent studies demonstrated that platelets could also enter CNS parenchyma and directly interact with neuronal cells. Within CNS, platelets become activated by recognizing major brain gangliosides on the surface of astrocytes and neurons and releasing a milieu of pro-inflammatory mediators, neurotrophic factors, and neurotransmitters. Platelet-derived factors directly stimulate neuronal electric and synaptic activity and promote the formation of new synapses and axonal regrowth near the site of damage. Despite such active involvement in response to CNS damage, the role of platelets in neurological disorders was not extensively studied, which will be the focus of this review.

From Provider to Advocate: The Complexities of Traumatic Brain Injury Prompt the Evolution of Provider Engagement

Treating a patient with traumatic brain injury requires an interdisciplinary approach because of the pervasive, profound and protean manifestations of this condition. In this review, key aspects of the medical history and review of systems will be described in order to highlight how the role of any provider must evolve to become a better patient advocate. Although this review is written from the vantage point of a vision care provider, it is hoped that patients, caregivers and providers will recognize the need for a team approach.

The influence of hydrogen ions on coagulation in traumatic brain injury, explored by molecular dynamics

Background: Patients in intensive care units with traumatic brain injuries (TBI) frequently present acid-base abnormalities and coagulability disorders, which complicate their condition.Objective: To identify protonation through in silico simulations of molecules involved in the process of coagulation in standard laboratory tests.Materials and methods: Ten patients with TBI were selected from the intensive care unit in addition to ten "healthy control subjects", and another nine patients as "disease control subjects"; the latter being a comparative group, corresponding to subjects with diabetes mellitus 2 (DM2). Fibrinogen, FVII, FVIII, FIX, FX, and D-dimer in the presence of acidification were evaluated in 20 healthy subjects in order to compare clinical results with molecular dynamics (MD), and to explain proton interactions and coagulation molecules.Results: The TBI group presented a slight, non-significant increase in D-dimer; but this was not present in "disease control subjects". Levels of fibrinogen, FVII, FIX, FX, and D-dimer were affected in the presence of acidification. We observed that various specific residues of coagulation factors "trap" ions.Conclusion: Protonation of tissue factor and factor VIIa may favor anticoagulant mechanisms, and protonation does not affect ligand binding sites of GPIIb/IIIa (PAC1) suggesting other causes for the low affinity to PAC1.

Intraoperative cell salvage is associated with reduced allogeneic blood requirements and has no significant impairment on coagulation function in patients undergoing cesarean delivery: a retrospective study

OBJECTIVE

The aim of the study is to examine the association between Intraoperative cell salvage (ICS), allogeneic blood transfusion (ABT) and coagulation function in obstetrics.

METHODS

A total of 486 pregnant women undergoing cesarean delivery, of whom 157 were enrolled in this retrospective study. Patients were divided into ICS group (n = 101, ICS used during operation) and control group (n = 56, ICS not used during operation). Clinical data, including plasma prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fib) and thrombin time (TT) levels, were collected from all patients preoperatively (within 12-24 h) and postoperatively (within 6-12 h) and analyzed by t test, two-way repeated-measures ANOVA and Spearman's correlation.

RESULTS

The use of ICS is associated with lower requirement rate for ABT (P < .001), while the blood loss was similar between the two groups (P = .990). Mean volume of ICS transfusion was 432.65 mL. Compared to preoperative values, the postoperative PT and APTT levels were significantly increased, while Fib was decreased in the two groups (all P < .01). No significant difference in coagulation function was observed between groups in preoperative and postoperative phase (P > .05). Furthermore, PT, APTT and TT after surgery were not correlated with the transfused volume of salvaged blood (P > .05) while the levels of Fib were negatively correlated with the volume (P < .01). In addition, there were no transfusion reactions in both two groups.

CONCLUSIONS

Intraoperative cell salvage is correlated with reduced allogeneic blood requirements but did not impair blood coagulation significantly in patients undergoing cesarean delivery.

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.

Early Identification of Acute Traumatic Coagulopathy Using Clinical Prediction Tools: A Systematic Review

: Background and objectives: Prompt identification of patients with acute traumatic coagulopathy (ATC) is necessary to expedite appropriate treatment. An early clinical prediction tool that does not require laboratory testing is a convenient way to estimate risk. Prediction models have been developed, but none are in widespread use. This systematic review aimed to identify and assess accuracy of prediction tools for ATC. Materials and Methods: A search of OVID Medline and Embase was performed for articles published between January 1998 and February 2018. We searched for prognostic and predictive studies of coagulopathy in adult trauma patients. Studies that described stand-alone predictive or associated factors were excluded. Studies describing prediction of laboratory-diagnosed ATC were extracted. Performance of these tools was described. Results: Six studies were identified describing four different ATC prediction tools. The COAST score uses five prehospital variables (blood pressure, temperature, chest decompression, vehicular entrapment and abdominal injury) and performed with 60% sensitivity and 96% specificity to identify an International Normalised Ratio (INR) of >1.5 on an Australian single centre cohort. TICCS predicted an INR of >1.3 in a small Belgian cohort with 100% sensitivity and 96% specificity based on admissions to resuscitation rooms, blood pressure and injury distribution but performed with an Area under the Receiver Operating Characteristic (AUROC) curve of 0.700 on a German trauma registry validation. Prediction of Acute Coagulopathy of Trauma (PACT) was developed in USA using six weighted variables (shock index, age, mechanism of injury, Glasgow Coma Scale, cardiopulmonary resuscitation, intubation) and predicted an INR of >1.5 with 73.1% sensitivity and 73.8% specificity. The Bayesian network model is an artificial intelligence system that predicted a prothrombin time ratio of >1.2 based on 14 clinical variables with 90% sensitivity and 92% specificity. Conclusions: The search for ATC prediction models yielded four scoring systems. While there is some potential to be implemented effectively in clinical practice, none have been sufficiently externally validated to demonstrate associations with patient outcomes. These tools remain useful for research purposes to identify populations at risk of ATC.

Higher plasma C-type lectin-like receptor 2 concentrations for prediction of higher risk of 30-day mortality in isolated severe blunt traumatic brain injury

BACKGROUND

Platelet activation is implicated in secondary brain injury following traumatic brain injury (TBI). C-type lectin-like receptor 2 (CLEC-2) is extensively expressed on platelets and participates in platelet activation. We investigate dthe prognostic significance of plasma CLEC-2 in TBI patients.

METHODS

One hundred and six patients with isolated severe blunt TBI and 106 healthy controls were prospectively investigated. Plasma CLEC-2 concentrations were detected and Glasgow coma scale (GCS) scores were recorded. The relationship between plasma CLEC-2 concentrations and 30-day mortality in addition to overall survival was determined using multivariate models.

RESULTS

Patients exhibited a substantially higher concentration of plasma CLEC-2 than healthy controls. Among patients, plasma CLEC-2 concentrations were remarkably increased in the GCS scores- and Rotterdam computerized tomography classification- dependent manner. As compared with survivors within posttraumatic 30 days, plasma CLEC-2 concentrations were remarkably raised in non-survivors. Rising plasma CLEC-2 concentration was independently associated with an enhanced risk of 30-day mortality and short overall survival time. Plasma CLEC-2 concentrations had a significantly high area under receiver operating characteristic curve for predicting 30-day mortality.

CONCLUSIONS

Incremental plasma CLEC-2 concentrations are intimately related to increasing trauma severity, in close association with increased 30-day death, indicating the prognostic role of plasma CLEC-2 in TBI.

The procoagulant molecule plasminogen activator inhibitor-1 is associated with injury severity and shock in patients with and without traumatic brain injury

BACKGROUND

Traumatic injury is associated with an increased risk of coagulopathy and venous thrombosis. plasminogen activator inhibitor-1 (PAI-1) is a procoagulant molecule that inhibits tPA/uPA, thrombomodulin, and activated protein C. We hypothesized that elevated PAI-1 levels would be associated with increased Injury Severity Score (ISS) in injured patients with and without traumatic brain injury and that PAI-1 levels would vary with injury type.

METHODS

We retrospectively analyzed demographic, ISS, and hemodynamic data from a prospectively collected database. Patients with traumatic injury requiring intensive care unit admission (n = 268) were classified as multiple injuries, isolated body, or isolated head based on Abbreviated Injury Severity score. Admission PAI-1 levels were quantified using a Luminex analyte platform. Univariate tests for association informed the construction of a multivariate model of the relationship between PAI-1 and ISS.

RESULTS

Plasminogen activator inhibitor-1 positively associated with ISS (p < 0.0001) and was highest in patients with ISS greater than 35 (p < 0.0001). Plasminogen activator inhibitor-1 was significantly different between multiple injuries, isolated body, and isolated head patients (p < 0.0001). On univariate analysis, age (p = 0.0011), hypotension (p = 0.0076), and alcohol intoxication (p = 0.0024) were all positively associated with PAI-1 level. Admission international normalized ratio was not associated with PAI-1 level (p = 0.638). After adjusting for age, sex, hypotension, and alcohol intoxication, higher PAI-1 levels were associated with higher ISS (p < 0.0001).

CONCLUSION

Elevated PAI-1 at admission is associated with higher ISS. This association is more pronounced in patients with hypotension. These findings suggest that PAI-1 levels may reflect the burden of endothelial damage and platelet activation after injury.

LEVEL OF EVIDENCE

Prognostic, level III.

Elevated plasma levels of TIMP-3 are associated with a higher risk of acute respiratory distress syndrome and death following severe isolated traumatic brain injury

Background:

Complications after injury, such as acute respiratory distress syndrome (ARDS), are common after traumatic brain injury (TBI) and associated with poor clinical outcomes. The mechanisms driving non-neurologic organ dysfunction after TBI are not well understood. Tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) is a regulator of matrix metalloproteinase activity, inflammation, and vascular permeability, and hence has plausibility as a biomarker for the systemic response to TBI.

Methods:

In a retrospective study of 182 patients with severe isolated TBI, we measured TIMP-3 in plasma obtained on emergency department arrival. We used non-parametric tests and logistic regression analyses to test the association of TIMP-3 with the incidence of ARDS within 8 days of admission and in-hospital mortality.

Results:

TIMP-3 was significantly higher among subjects who developed ARDS compared with those who did not (median 2810 pg/mL vs. 2260 pg/mL, p=0.008), and significantly higher among subjects who died than among those who survived to discharge (median 2960 pg/mL vs. 2080 pg/mL, p<0.001). In an unadjusted logistic regression model, for each SD increase in plasma TIMP-3, the odds of ARDS increased significantly, OR 1.5 (95% CI 1.1 to 2.1). This association was only attenuated in multivariate models, OR 1.4 (95% CI 1.0 to 2.0). In an unadjusted logistic regression model, for each SD increase in plasma TIMP-3, the odds of death increased significantly, OR 1.7 (95% CI 1.2 to 2.3). The magnitude of this association was greater in a multivariate model adjusted for markers of injury severity, OR 1.9 (95% CI 1.2 to 2.8).

Discussion:

TIMP-3 may play an important role in the biology of the systemic response to brain injury in humans. Along with clinical and demographic data, early measurements of plasma biomarkers such as TIMP-3 may help identify patients at higher risk of ARDS and death after severe isolated TBI.

Level of evidence

III.

Adenosine, lidocaine, and Mg2+ (ALM) resuscitation fluid protects against experimental traumatic brain injury

BACKGROUND

Currently, no drug therapy prevents secondary injury progression after traumatic brain injury (TBI). Our aim was to investigate the effects of small-volume intravenous adenosine, lidocaine, and Mg (ALM) resuscitation fluid after moderate TBI in a rat fluid-percussion injury model.

METHODS

Anesthetized, mechanically ventilated male Sprague-Dawley rats (449 ± 5 g) were randomly assigned to one of four groups: (1) sham (craniotomy without TBI), (2) no-treatment, (3) saline-control, or (4) ALM therapy groups (all n = 16). A subdural probe was implanted in eight animals per group to measure cerebral blood flow. Fifteen minutes after moderate TBI was induced with lateral fluid percussion injury (2.57 atm), a single 3% NaCl ± ALM bolus (0.7 mL/kg) was injected intravenously, and after 60 minutes (Phase 1), 0.9% NaCl ± ALM stabilization "drip" (0.5 mL/kg per hour) was administered for 3 hours (Phase 2).

RESULTS

Mortality (without subdural brain probe) was 25% (saline controls) and 0% (ALM). Sixty minutes after bolus, ALM significantly increased cardiac function, cortical blood flow (CBF; approximately threefold) and blunted systemic inflammation compared to saline controls. Three hours after infusion drip, ALM improved left ventricular function, supported higher CBF, decreased proinflammatory cytokines systemically (IL-1β, tumor necrosis factor α, and regulated on activation, normal T cell expressed and secreted [RANTES]), increased anti-inflammatory cytokines in brain tissue (IL-10, IL-4), lowered brain injury markers (neuron-specific enolase, Syndecan-1, HMGB-1), reduced coagulopathy, increased platelet aggregation, and maintained baseline fibrinogen levels. Saline-controls were proinflammatory (brain, heart, lung, and blood) and hypocoagulable with neurogenic enlargement of the right side of the heart. Survival time significantly correlated with plasma neuron-specific enolase (p = 0.001) and CBF at 180 minutes (p = 0.009), and CBF correlated with brain anti-inflammatory cytokines (p = 0.001-0.034).

CONCLUSION

After moderate TBI, ALM resuscitation fluid increased survival and protected against early secondary injury by reducing coagulopathy, inflammation, and platelet dysfunction.

Plasma D-dimer safely reduces unnecessary CT scans obtained in the evaluation of pediatric head trauma

PURPOSE

Serum D-dimer has been proposed as a biomarker to aid in the diagnosis of pediatric traumatic brain injury (TBI). We investigated the accuracy of D-dimer in predicting the absence of TBI and evaluated the degree by which D-dimer could limit unnecessary computed tomography scans of the head (CTH).

METHODS

Retrospective review of patients with suspected TBI from 2011 to 2013 who underwent evaluation with CTH and quantitative D-dimer. D-dimer levels were compared among patients with clinically-important TBI (ciTBI), TBI, isolated skull fracture and no injury.

RESULTS

Of the 663 patients evaluated for suspected TBI, ciTBI was identified in 116 (17.5%), TBI in 77 (11.6%), skull fracture in 61 (9.2%) and no head injury in 409 (61.7%). Patients with no head injury had significantly lower D-dimer values (1531±1791pg/μL) compared to those with skull fracture, TBI and ciTBI (2504±1769, 2870±1633 and 4059±1287pg/μL, respectively, p<0.005). Using a D-dimer value <750pg/μL as a negative screen, no ciTBIs would be missed and 209 CTHs avoided (39.7% of total).

CONCLUSION

Low plasma D-dimer predicts the absence of ciTBI for pediatric patient with suspected TBI. Incorporating D-dimer into current diagnostic algorithms may significantly limit the number of unnecessary CTHs performed in this population.

TYPE OF STUDY

Study of diagnostic test.

LEVEL OF EVIDENCE

I.

Assessment of Platelet Function in Traumatic Brain Injury-A Retrospective Observational Study in the Neuro-Critical Care Setting

BACKGROUND

Despite seemingly functional coagulation, hemorrhagic lesion progression is a common and devastating condition following traumatic brain injury (TBI), stressing the need for new diagnostic techniques. Multiple electrode aggregometry (MEA) measures platelet function and could aid in coagulopathy assessment following TBI. The aims of this study were to evaluate MEA temporal dynamics, influence of concomitant therapy, and its capabilities to predict lesion progression and clinical outcome in a TBI cohort.

MATERIAL AND METHODS

Adult TBI patients in a neurointensive care unit that underwent MEA sampling were retrospectively included. MEA was sampled if the patient was treated with antiplatelet therapy, bled heavily during surgery, or had abnormal baseline coagulation values. We assessed platelet activation pathways involving the arachidonic acid receptor (ASPI), P2Y12 receptor, and thrombin receptor (TRAP). ASPI was the primary focus of analysis. If several samples were obtained, they were included. Retrospective data were extracted from hospital charts. Outcome variables were radiologic hemorrhagic progression and Glasgow Outcome Scale assessed prospectively at 12 months posttrauma. MEA levels were compared between patients on antiplatelet therapy. Linear mixed effect models and uni-/multivariable regression models were used to study longitudinal dynamics, hemorrhagic progression and outcome, respectively.

RESULTS

In total, 178 patients were included (48% unfavorable outcome). ASPI levels increased from initially low values in a time-dependent fashion (p < 0.001). Patients on cyclooxygenase inhibitors demonstrated low ASPI levels (p < 0.001), while platelet transfusion increased them (p < 0.001). The first ASPI (p = 0.039) and TRAP (p = 0.009) were significant predictors of outcome, but not lesion progression, in univariate analyses. In multivariable analysis, MEA values were not independently correlated with outcome.

CONCLUSION

A general longitudinal trend of MEA is identified in this TBI cohort, even in patients without known antiplatelet therapies. Values appear also affected by platelet inhibitory treatment and by platelet transfusions. While significant in univariate models to predict outcome, MEA values did not independently correlate to outcome or lesion progression in multivariable analyses. Further prospective studies to monitor coagulation in TBI patients are warranted, in particular the interpretation of pathological MEA values in patients without antiplatelet therapies.

Decreased mortality in patients with isolated severe blunt traumatic brain injury receiving higher plasma to packed red blood cells transfusion ratios

INTRODUCTION

Higher transfusion ratios of plasma to packed red blood cells (PRBC) and platelets (PLT) to PRBC have been shown to be associated with decreased mortality in major trauma patients. However, little is known about the effect of transfusion ratios on mortality in patients with isolated severe traumatic brain injury (TBI). The aim of this study was to investigate the effect of transfusion ratios on mortality in patients with isolated severe blunt TBI. We hypothesized that higher transfusion ratios of plasma to PRBC and PLT to PRBC are associated with a lower mortality rate in these patients.

METHODS

Retrospective observational study. Patients with isolated severe blunt TBI (AIS head≥3, AIS extracranial <3) admitted to an urban level I trauma centre were included. Clinical data were extracted from the institution's trauma registry, blood transfusion data from the blood bank database. The effect of higher transfusion ratios on in-hospital mortality was analysed using univariate and multivariable regression analysis.

RESULTS

A total of 385 patients were included. Median age was 32 years (IQR 2-50), 71.4% were male, and 76.6% had an ISS≥16. Plasma:PRBC transfusion ratios≥1 were identified as an independent predictor for decreased in-hospital mortality (adjusted OR 0.43 [CI 0.22-0.81]). PLT:PRBC transfusion ratios≥1 were not significantly associated with mortality (adjusted OR 0.39 [CI 0.08-1.92]).

CONCLUSION

This study revealed plasma to PRBC transfusion ratios≥1 as an independent predictor for decreased in-hospital mortality in patients with isolated severe blunt TBI.

Coagulopathy and haemorrhagic progression in traumatic brain injury: advances in mechanisms, diagnosis, and management

Normal haemostasis depends on an intricate balance between mechanisms of bleeding and mechanisms of thrombosis, and this balance can be altered after traumatic brain injury (TBI). Impaired haemostasis could exacerbate the primary insult with risk of initiation or aggravation of bleeding; anticoagulant use at the time of injury can also contribute to bleeding risk after TBI. Many patients with TBI have abnormalities on conventional coagulation tests at admission to the emergency department, and the presence of coagulopathy is associated with increased morbidity and mortality. Further blood testing often reveals a range of changes affecting platelet numbers and function, procoagulant or anticoagulant factors, fibrinolysis, and interactions between the coagulation system and the vascular endothelium, brain tissue, inflammatory mechanisms, and blood flow dynamics. However, the degree to which these coagulation abnormalities affect TBI outcomes and whether they are modifiable risk factors are not known. Although the main challenge for management is to address the risk of hypocoagulopathy with prolonged bleeding and progression of haemorrhagic lesions, the risk of hypercoagulopathy with an increased prothrombotic tendency also warrants consideration.

Point-of-care testing in the acute management of traumatic brain injury: Identifying the coagulopathic patient

Background:

The use of anticoagulants or antiplatelet medications has become increasingly common and is a well-established risk factor for worsening of hemorrhages in trauma patients. The current study addresses the need to investigate the efficacy of point-of-care tests (POC) as an adjunct to conventional coagulation testing in traumatic brain injury (TBI) patients.

Methods:

A retrospective review of 190 TBI patients >18 years of age who underwent both conventional and POC testing as part of their admission coagulopathy workup was conducted. Coagulation deficiency was defined as an international normalized ratio (INR) >1.4, a reaction time (r-value) on rapid thromboelastography >50 seconds, or a VerifyNow Aspirin (VN-ASA) level of < 550 Aspirin Reaction Units.

Results:

Among 190 patients, 91 (48%) disclosed a history of either warfarin or antiplatelet use or had documented INR >1.4. Of the 18 (9%) patients who reported warfarin use, 83% had elevated INR and 61% had elevated r-value. However, 41% of the patients without reported anticoagulant usage revealed significantly elevated r-value consistent with a post-traumatic hypocoagulable state. Of 64 (34%) patients who reported taking ASA, 51 (80%) demonstrated therapeutic VN-ASA. Interestingly, 31 of 126 (25%) patients not reporting ASA use were also noted to have therapeutic VN-ASA suggestive of platelet dysfunction.

Conclusions:

The coagulopathy POC panel consisting of r-TEG and VN-ASA successfully identified a subset of TBI patients with an occult coagulopathy that would have otherwise been missed. Standardization of these POC assays on admission in TBI may help guide patient resuscitation in the acute setting.

Tripartite Stratification of the Glasgow Coma Scale in Children with Severe Traumatic Brain Injury and Mortality: An Analysis from a Multi-Center Comparative Effectiveness Study

The Glasgow Coma Scale (GCS) score has not been validated in children younger than 5 years and the clinical circumstances at the time of assignment can limit its applicability. This study describes the distribution of GCS scores in the population, the relationship between injury characteristics with the GCS score, and the association between the tripartite stratification of the GCS on mortality in children with severe traumatic brain injury (TBI). The first 200 children from a multi-center comparative effectiveness study in severe TBI (inclusion criteria: age 0-18 years, GCS ≤8 at the time of intracranial pressure [ICP] monitoring) were analyzed. After tripartite stratification of GCS scores (Group A, GCS 3; Group B, GCS 4 - 5; and Group C, GCS 6 - 8), analyses of variance and chi-square testing were performed. Mean age was 7.61 years ±5.33 and mortality was 19.1%. There was no difference in etiology or type/mechanism of injury between groups. However, groups demonstrated differences in neuromuscular blockade, endotracheal intubation, pre-hospital events (cardiac arrest and apnea), coagulopathy, and pupil response. Mortality between groups was different (42.2% Group A, 22.6% Group B, and 3.8% Group C; p < 0.001), and adding pupil response improved mortality associations. In children younger than 5 years of age, a similar relationship between GCS and mortality was observed. Overall, GCS score at the time of ICP monitor placement is strongly associated with mortality across the pediatric age range. Development of models with GCS and other factors may allow identification of subtypes of children after severe TBI for future studies.

Management of neurologic complications of coagulopathies

Coagulopathy is common in intensive care units (ICUs). Many physiologic derangements lead to dysfunctional hemostasis; these may be either congenital or acquired. The most devastating outcome of coagulopathy in the critically ill is major bleeding, defined by transfusion requirement, hemodynamic instability, or intracranial hemorrhage. ICU coagulopathy often poses complex management dilemmas, as bleeding risk must be tempered with thrombotic potential. Coagulopathy associated with intracranial hemorrhage bears directly on prognosis and outcome. There is a paucity of high-quality evidence for the management of coagulopathies in neurocritical care; however, data derived from studies of patients with intraparenchymal hemorrhage may inform treatment decisions. Coagulopathy is often broadly defined as any derangement of hemostasis resulting in either excessive bleeding or clotting, although most typically it is defined as impaired clot formation. Abnormalities in coagulation testing without overt clinical bleeding may also be considered evidence of coagulopathy. This chapter will focus on acquired conditions, such as organ failure, pharmacologic therapies, and platelet dysfunction that are associated with defective clot formation and result in, or exacerbate, intracranial hemorrhage, specifically spontaneous intraparenchymal hemorrhage and traumatic brain injury.

Platelet adenosine diphosphate inhibition in trauma patients by thromboelastography correlates with paradoxical increase in platelet dense granule content by flow cytometry

BACKGROUND

The mechanism of platelet dysfunction in acute traumatic coagulopathy is unknown. Traumatic brain injury is hypothesized as a cause, while some investigators presume platelets become "exhausted." We hypothesized that platelet hyperstimulation and consumption resulting from trauma leads to decreased platelet function secondary to depletion of platelet granules.

METHODS

Twenty-five trauma patients were divided into traumatic brain injury and no traumatic brain injury groups. Healthy volunteers served as controls. All had thromboelastography with platelet mapping and flow cytometric assays of mepacrine performed. Mepacrine uptake in unstimulated platelets was used for quantification of platelet content of dense granules.

RESULTS

Twelve patients with traumatic brain injury and 13 patients without traumatic brain injury were enrolled. Twenty-one trauma patients showed adenosine diphosphate inhibition (>30%) on thromboelastography with platelet mapping compared with the healthy volunteers who served as controls (P < .01). Mepacrine assay showed a difference in mean fluorescent intensity for all trauma patients of 4,259 ± 1,341 compared with controls of 3,143 ± 709 (P = .044), correlating with greater quantities of dense granules. Neither adenosine diphosphate inhibition nor average difference in mean fluorescent intensity between traumatic brain injury and no traumatic brain injury groups were significant (P = .2).

CONCLUSION

Trauma patients maintain their dense granule, contradicting the theory of platelet granule exhaustion as the etiology for platelet dysfunction in traumatic brain injury.

From trash to treasure: The untapped potential of endothelial microparticles in neurovascular diseases

Discovered in 1947, microparticles (MP) represent a group of sub-micron cell-derived particles isolated by high speed centrifugation. Once regarded as cellular 'trash', in the past decade MP have gained tremendous attention in both basic sciences and medical research both as biomarkers and mediators of infection, injury and response to therapy. Because MP bear cell surface markers derived from parent cells, accumulate in extracellular fluids (plasma, serum, milk, urine, cerebrospinal fluid) MP based tests are being developed commercially as important components in 'liquid biopsy' approaches, providing valuable readouts in cardiovascular disease and cancer, as well as stroke, Alzheimer's disease and Multiple Sclerosis. Importantly, MP have been reported as mobile transport vectors in the intercellular transfer of mRNAs, microRNAs, lipids and proteins. Here we discuss MP structure, properties and functions with particular relevance to neurological and neurovascular diseases.

A meta-analysis to determine the effect of coagulopathy on intracranial haematoma progression in adult patients with isolated blunt head trauma

Coagulopathy following isolated traumatic brain injury is a well-recognised complication especially in patients with severe head injury. Intracranial haematoma progression is a major adverse factor affecting outcome in patients with traumatic brain injury. Coagulopathy is an important risk factor for haematoma progression. The aim of this meta-analysis was to determine the magnitude of effect of coagulopathy on intracranial haematoma progression in patients with isolated traumatic brain injury. Studies comparing patients with traumatic brain injury, coagulopathy and haematoma progression to patients with traumatic brain injury, haematoma progression and no coagulopathy were identified. The search was performed using Medline via the PubMed interface; no limits were placed on the language. In total 12 studies were identified as being suitable for the meta-analysis. Significant heterogeneity was present between the studies as demonstrated by an I2 = 80.185. The fixed effects model was considered to be the preferred model and this produced a pooled odds ratio of 6.897 (95% confidence interval: 5.495–8.655). The results of this meta-analysis show that traumatic brain injury-induced coagulopathy is a significant factor in haematoma progression in patients with isolated traumatic brain injury.

Microparticles impact coagulation after traumatic brain injury

BACKGROUND

The pathophysiology that drives the subacute hypercoagulable state commonly seen after traumatic brain injury (TBI) is not well understood. Alterations caused by TBI in platelet and microparticle (MP) numbers and function have been suggested as possible causes; however, the contributions of platelets and MPs are currently unknown.

MATERIALS AND METHODS

A weight-drop technique of TBI using a murine model of moderate head injury was used. Blood was collected at intervals after injury. MP enumeration and characterization were performed using Nanoparticle Tracking Analysis, and platelet counts and coagulation parameters were determined using thromboelastometry. A MP procoagulant assay was used to compare activity between injured and sham mice.

RESULTS

At 24 h after injury, there were no changes in circulating platelet numbers. However, there was a decrease in platelet contribution to clot formation. In contrast, there was a decline in circulating total MP numbers. When MPs from sham mice were added to the blood from head-injured animals, there was a normalization of platelet contribution to clot formation. Conversely, when MPs from TBI mice were added to sham blood, there was a significant decrease in platelet contribution to clot formation. Notably, there was an increase in MP procoagulant activity in head-injured mice.

CONCLUSIONS

MPs generated after TBI likely contribute to altered coagulation after head injury and may play a key role in the development of a posttraumatic hypercoagulable state in TBI patients.