Does an early, balanced resuscitation strategy reduce the incidence of hypofibrinogenemia in hemorrhagic shock?

Objectives: Some centers have recommended including concentrated fibrinogen replacement in massive transfusion protocols (MTPs). Given our center's policy of aggressive early balanced resuscitation (1:1:1), beginning prehospital, we hypothesized that our rates of hypofibrinogenemia may be lower than those previously reported. Methods: In this retrospective cohort study, patients presenting to our trauma center November 2017 to April 2021 were reviewed. Patients were defined as hypofibrinogenemic (HYPOFIB) if admission fibrinogen <150 or rapid thrombelastography angle <60. Univariate and multivariable analyses assessed risk factors for HYPOFIB. Inverse probability of treatment weighting analyses assessed the relationship between cryoprecipitate administration and outcomes. Results: Of 29 782 patients, 6618 level 1 activations, and 1948 patients receiving emergency release blood, <1%, 2%, and 7% were HYPOFIB. HYPOFIB patients were younger, had higher head Abbreviated Injury Scale value, and had worse coagulopathy and shock. HYPOFIB had lower survival (48% vs 82%, p<0.001), shorter time to death (median 28 (7, 50) vs 36 (14, 140) hours, p=0.012), and were more likely to die from head injury (72% vs 51%, p<0.001). Risk factors for HYPOFIB included increased age (OR (95% CI) 0.98 (0.96 to 0.99), p=0.03), head injury severity (OR 1.24 (1.06 to 1.46), p=0.009), lower arrival pH (OR 0.01 (0.001 to 0.20), p=0.002), and elevated prehospital red blood cell to platelet ratio (OR 1.20 (1.02 to 1.41), p=0.03). Among HYPOFIB patients, there was no difference in survival for those that received early cryoprecipitate (within 2 hours; 40 vs 47%; p=0.630). On inverse probability of treatment weighted analysis, early cryoprecipitate did not benefit the full cohort (OR 0.52 (0.43 to 0.65), p<0.001), nor the HYPOFIB subgroup (0.28 (0.20 to 0.39), p<0.001). Conclusions: Low rates of hypofibrinogenemia were found in our center which treats hemorrhage with early, balanced resuscitation. Previously reported higher rates may be partially due to unbalanced resuscitation and/or delay in resuscitation initiation. Routine empiric inclusion of concentrated fibrinogen replacement in MTPs is not supported by the currently available data. Level of evidence: Level III.

Exposure to statin therapy decreases the incidence of venous thromboembolism after trauma.

INTRODUCTION: Venous thromboembolism (VTE) is a leading cause of morbidity and mortality in trauma patients, despite chemoprophylaxis. Statins have been shown capable of acting upon the endothelium. We hypothesized that statin therapy in the pre- or in-hospital settings leads to a decreased incidence of VTE. METHODS: We conducted a retrospective cohort study of injured patients who received statin therapy pre- or in-hospital. Adult, highest-level trauma activation patients admitted January 2018 - June 2022 were included. Patients on prehospital anticoagulants, history of inherited bleeding disorder, and who died within the first 24 hours were excluded. Statin users were matched to non-users by statin use indications including age, current heart and cardiovascular conditions and history, hyperlipidemia, injury severity, and body mass index. Time to in-hospital statin initiation and occurrence of VTE and other complications within 60 days were collected. Differences between groups were determined by univariate, multivariable logistic regression, and Cox proportional hazard analyses. RESULTS: Of 3,062 eligible patients, 79 were statin users that were matched to 79 non-users. There were no differences in admissions demographics, vital signs, injury pattern, transfusion volumes, lengths of stay, or mortality between groups. The overall VTE incidence was 10.8% (17/158). Incidence of VTE in statin users was significantly lower (3%) than non-users (19%; P = 0.003). Differences between statin users and non-users were observed for rates of DVT (0% vs 9%), PE (3% vs 15%), and sepsis (0% vs 5%). Exposure to statins was associated with an 82% decreased risk of developing VTE (hazard ratio = 0.18, 95% CI 0.04 - 0.86; P = 0.033). CONCLUSIONS: Statin exposure was associated with decline in VTE and lower individual rates of DVT, PE, and sepsis. Our findings indicate that statins should be evaluated further as a possible adjunctive therapy for VTE chemoprophylaxis after traumatic injury. LEVEL OF EVIDENCE AND STUDY TYPE: Level III, Retrospective Cohort Study.

Venous Thromboembolism: Review of Clinical Challenges, Biology, Assessment, Treatment, and Modeling.

Venous thromboembolism (VTE) is a massive clinical challenge, annually affecting millions of patients globally. VTE is a particularly consequential pathology, as incidence is correlated with extremely common risk factors, and a large cohort of patients experience recurrent VTE after initial intervention. Altered hemodynamics, hypercoagulability, and damaged vascular tissue cause deep-vein thrombosis and pulmonary embolism, the two permutations of VTE. Venous valves have been identified as likely locations for initial blood clot formation, but the exact pathway by which thrombosis occurs in this environment is not entirely clear. Several risk factors are known to increase the likelihood of VTE, particularly those that increase inflammation and coagulability, increase venous resistance, and damage the endothelial lining. While these risk factors are useful as predictive tools, VTE diagnosis prior to presentation of outward symptoms is difficult, chiefly due to challenges in successfully imaging deep-vein thrombi. Clinically, VTE can be managed by anticoagulants or mechanical intervention. Recently, direct oral anticoagulants and catheter-directed thrombolysis have emerged as leading tools in resolution of venous thrombosis. While a satisfactory VTE model has yet to be developed, recent strides have been made in advancing in silico models of venous hemodynamics, hemorheology, fluid-structure interaction, and clot growth. These models are often guided by imaging-informed boundary conditions or inspired by benchtop animal models. These gaps in knowledge are critical targets to address necessary improvements in prediction and diagnosis, clinical management, and VTE experimental and computational models.

Low molecular weight heparin decreases pro-coagulant activity in clinical MSC products.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are multipotent adult cells that can be isolated from tissues including bone marrow [MSC(BM)], adipose [MSC(AT)] and umbilical cord [MSC(CT)]. Previous studies have linked expression of tissue factor (TF) on MSC surfaces to a procoagulant effect. Venous thromboembolism (VTE), immediate blood-mediated inflammatory reaction (IBMIR) and microvascular thrombosis remain a risk with intravascular MSC therapy. We examined the effect of low molecular weight heparin (LMWH) on clinical-grade MSCs using calibrated automated thrombography (CAT). METHODS: Clinical grade MSC(BM)s, MSC(AT)s and MSC(CT)s harvested at passage 4 were added to normal pooled plasma (NPP) to a final concentration of either 400 000 or 50 000 cells/mL. LMWH was added to plasma in increments of 0.1 U/mL. Thrombin generation (TG) was measured using CAT. Flow cytometry was conducted on the cells to measure MSC phenotype and TF load. RESULTS: Presence of MSCs decreased lag time and increased peak TG. All cell lines demonstrated a dose response to LMWH, with MSC(AT) demonstrating the least thrombogenicity and most sensitivity to LMWH. TG was significantly reduced in all cell lines at doses of 0.2 U/mL LMWH and higher. DISCUSSION: All MSC types and concentrations had a decrease in peak thrombin and TG with increasing amounts of LMWH. While this in vitro study cannot determine optimal dosing, it suggests that LMWH can be effectively used to lower the risk of VTE associated with intravascular administration of MSCs. Future in vivo work can be done to determine optimal dosing and effect on IBMIR and VTE.

Fibrinogen Fragment X Mediates Endothelial Barrier Disruption via Suppression of VE-Cadherin.

INTRODUCTION: Major traumatic injury is associated with early hemorrhage-related and late-stage deaths due to multiple organ failure (MOF). While improvements to hemostatic resuscitation have significantly reduced hemorrhage-related deaths, the incidence of MOF among trauma patients remains high. Dysregulation of vascular endothelial cell (EC) barrier function is a central mechanism in the development of MOF; however, the mechanistic triggers remain unknown. Accelerated fibrinolysis occurs in a majority of trauma patients, resulting in high circulating levels of fibrin(ogen) degradation products, such as fragment X. To date, the relationship between fragment X and EC dysregulation and barrier disruption is unknown. The goal of this study was to determine the effects of fragment X on EC barrier integrity and expression of paracellular junctional proteins that regulate barrier function. METHODS: Human lung microvascular endothelial cells (HLMVECs) were treated with increasing concentrations of fragment X (1, 10, and 100 µg/mL), and barrier function was monitored using the xCELLigence live-cell monitoring system. Quantitative PCR (qPCR) was performed to measure changes in EC expression of 84 genes. Immunofluorescent (IF) cytostaining was performed to validate qPCR findings. RESULTS: Fragment X treatment significantly increased endothelial permeability over time (P < 0.05). There was also a significant reduction in VE-cadherin mRNA expression in fragment X-treated HLMVECs compared to control (P = 0.01), which was confirmed by IF staining. CONCLUSIONS: Fragment X may induce EC hyperpermeability by reducing VE-cadherin expression. This suggests that a targeted approach to disrupting EC-fragment X interactions could mitigate EC barrier disruption, organ edema, and MOF associated with major trauma.

TIME-DEPENDENT CHANGES IN PROINFLAMMATORY MEDIATORS ARE ASSOCIATED WITH TRAUMA-RELATED VENOUS THROMBOEMBOLISM.

ABSTRACT: Background: Tissue trauma and hemorrhage result in pronounced activation of the innate immune system. Given known crosstalk between inflammation and coagulation, soluble inflammatory mediators could be associated with venous thromboembolisms (VTEs) after major trauma. Objectives : This study aimed to identify plasma inflammatory mediators that are independent predictors of VTE risk in trauma patients. Methods: We performed a secondary analysis of the Pragmatic Randomized Optimal Platelets and Plasma Ratios (PROPPR) study. Plasma levels of 27 cytokines/chemokines were measured by Bio-Plex at admission and 2, 4, 6, 12, 24, 48, and 72 h later. Patients who died from exsanguination or within 24 h were excluded. Mann-Whitney tests were performed to assess no-VTE and VTE groups at each time point. Multivariable logistic regression was used to determine the adjusted effects of inflammatory mediators on VTE risk. Results: Eighty-six of the 575 patients (15%) included developed VTE. Interleukin (IL)-1ra, IL-6, IL-8, IL-10, eotaxin, granulocyte colony-stimulating factor, interferon-γ-inducible protein, monocyte chemoattractant protein 1 (MCP-1), and chemokine ligand 5 (regulated on activation, normal T cell expressed and secreted) were all significantly increased among VTE patients. Multivariable analyses demonstrated that IL-6, IL-8, interferon-γ-inducible protein, and MCP-1 were independently associated with VTE. Cox proportional hazards modeling identified IL-6, IL-8, and MCP-1 as independent predictors of accelerated VTE development. We identified significant correlations between inflammation and markers of coagulation and endothelial activation. Conclusion: Sustained systemic inflammation is a key driver of VTE risk after major trauma. Therapeutics targeting innate immune activation should be considered for development of future multimodal strategies to augment current VTE prophylaxis.

Design and Development of a Clot Burst Pressure Device to Investigate Resuscitation Strategies.

INTRODUCTION: A reduction in clot strength is a hallmark feature of trauma-induced coagulopathy. A better understanding of clot integrity can optimize resuscitation strategies. We designed a device to gauge clot strength by pressurizing fluids over a formed clot and measuring the pressure needed to dislodge the clot. We hypothesized that this device could distinguish between clots formed in hypocoagulable and hypercoagulable states by observing differences in the clot burst pressure. METHODS: Whole blood from healthy volunteers was collected into sodium citrate tubes and was treated with heparin or fibrinogen to generate clots in a hypocoagulable or hypercoagulable state, respectively. Small bore holes were drilled into polystyrene plates, and recalcified blood was pipetted into the holes. Plates were incubated at 37°C for 30 min to form clots. A pressure cap with an inlet for fluid from a syringe pump and an outlet leading to a measurement column was secured in the wells with a watertight seal. RESULTS: Clot burst pressure was normalized to individual baseline values to account for inherent differences in clot strength. The 1.0 g/L and 2.0 g/L fibrinogen groups were 1.65 ± 0.07 (P = 0.0078) and 2.26 ± 0.16 (P = 0.0078) times as strong as baseline, respectively. The 0.10, 0.15, or 0.20 USP units/mL groups were 0.388 ± 0.07 (P = 0.125), 0.31 ± 0.07 (P = 0.125), 0.21 ± 0.07 (P = 0.125) times as strong as baseline, respectively. Data were analyzed using Wilcoxon matched pairs signed rank testing. CONCLUSIONS: This device tests clot strength using burst pressure, an easily interpreted clinical parameter not measured in existing devices. Future work can test blood from trauma patients to better understand trauma pathophysiology.

Hydrogen Sulfide Ameliorates SARS-CoV-2-Associated Lung Endothelial Barrier Disruption.

Recent studies have confirmed that lung microvascular endothelial injury plays a critical role in the pathophysiology of COVID-19. Our group and others have demonstrated the beneficial effects of H2S in several pathological processes and provided a rationale for considering the therapeutic implications of H2S in COVID-19 therapy. Here, we evaluated the effect of the slow-releasing H2S donor, GYY4137, on the barrier function of a lung endothelial cell monolayer in vitro, after challenging the cells with plasma samples from COVID-19 patients or inactivated SARS-CoV-2 virus. We also assessed how the cytokine/chemokine profile of patients' plasma, endothelial barrier permeability, and disease severity correlated with each other. Alterations in barrier permeability after treatments with patient plasma, inactivated virus, and GYY4137 were monitored and assessed by electrical impedance measurements in real time. We present evidence that GYY4137 treatment reduced endothelial barrier permeability after plasma challenge and completely reversed the endothelial barrier disruption caused by inactivated SARS-CoV-2 virus. We also showed that disease severity correlated with the cytokine/chemokine profile of the plasma but not with barrier permeability changes in our assay. Overall, these data demonstrate that treatment with H2S-releasing compounds has the potential to ameliorate SARS-CoV-2-associated lung endothelial barrier disruption.

Injury-induced endotheliopathy: What you need to know.

ABSTRACT: The endotheliopathy of trauma involves a complex interplay between the glycocalyx, von Willebrand factor, and platelets that leads to abnormalities in coagulation, inflammation, and endothelial cell (EC) function. The current review presents a synopsis of EC function under homeostatic conditions, the structure and function of the endothelial glycocalyx; mechanisms of EC injury and activation after trauma; pathological consequences of the EoT at the cellular level; and clinical implications of the EoT. Recent evidence is presented that links the EoT to extracellular vesicles and hyperadhesive ultralarge von Willebrand factor multimers through their roles in coagulopathy. Lastly, potential therapeutics to mitigate the EoT are discussed. Most research to date has focused on blood products, primarily plasma, and its contribution to restoring postinjury EC dysfunction. Additional therapeutic adjuvants that target the glycocalyx, ultralarge von Willebrand factor, low ADAMTS-13, and pathologic extracellular vesicles are reviewed. Much of the pathobiology of EoT is known, but a better mechanistic understanding can help guide therapeutics to further repair the EoT and improve patient outcomes.

Soluble endothelial protein C receptor is an independent predictor of venous thromboembolism after severe injury: Secondary analysis of a prospective cohort study.

BACKGROUND: Venous thromboembolism is a leading cause of morbidity after trauma. Endothelial cells are essential regulators of coagulation. Although endothelial cell dysregulation is widely reported after trauma, the link between endothelial injury and venous thromboembolism has not been reported. METHODS: We conducted a secondary analysis of the Pragmatic Randomized Optimal Platelets and Plasma Ratios study. Deaths from hemorrhage or within 24 hours were excluded. Venous thromboembolism was diagnosed by duplex ultrasound or chest computed tomography. Endothelial markers soluble endothelial protein c receptor, thrombomodulin, and syndecan-1 were measured in plasma by enzyme-linked immunosorbent assay and compared over the first 72 hours from admission using the Mann-Whitney test. Multivariable logistic regression assessed the adjusted effects of endothelial markers on venous thromboembolism risk. RESULTS: Of 575 patients enrolled, 86 developed venous thromboembolism (15%). The median time to venous thromboembolism was 6 days ([Q1, Q3], [4, 13]). No differences were identified in demographics or injury severity. Soluble endothelial protein c receptor, thrombomodulin, and syndecan-1 showed significant increases over time among patients who developed venous thromboembolism compared to those who did not. Using the last available values, patients were stratified into high and low-soluble endothelial protein c receptor, thrombomodulin, and syndecan-1 groups. Multivariable analyses revealed an independent association between elevated soluble endothelial protein c receptor and venous thromboembolism risk (odds ratio 1.63; 95% confidence interval 1.01, 2.63; P = .04). Cox proportional hazards modeling demonstrated a strong yet nonsignificant trend between elevated soluble endothelial protein c receptor and time to venous thromboembolism. CONCLUSION: Plasma markers of endothelial injury, particularly soluble endothelial protein c receptor, are strongly associated with trauma-related venous thromboembolism. Therapeutics targeting endothelial function could mitigate the incidence of venous thromboembolism after trauma.

A 3-O-sulfated heparan sulfate dodecasaccharide (12-mer) suppresses thromboinflammation and attenuates early organ injury following trauma and hemorrhagic shock.

Introduction: Dysregulated inflammation and coagulation are underlying mechanisms driving organ injury after trauma and hemorrhagic shock. Heparan sulfates, cell surface glycosaminoglycans abundantly expressed on the endothelial surface, regulate a variety of cellular processes. Endothelial heparan sulfate containing a rare 3-O-sulfate modification on a glucosamine residue is anticoagulant and anti-inflammatory through high-affinity antithrombin binding and sequestering of circulating damage-associated molecular pattern molecules. Our goal was to evaluate therapeutic potential of a synthetic 3-O-sulfated heparan sulfate dodecasaccharide (12-mer, or dekaparin) to attenuate thromboinflammation and prevent organ injury. Methods: Male Sprague-Dawley rats were pre-treated subcutaneously with vehicle (saline) or dekaparin (2 mg/kg) and subjected to a trauma/hemorrhagic shock model through laparotomy, gut distention, and fixed-pressure hemorrhage. Vehicle and dekaparin-treated rats were resuscitated with Lactated Ringer's solution (LR) and compared to vehicle-treated fresh-frozen-plasma-(FFP)-resuscitated rats. Serial blood samples were collected at baseline, after induction of shock, and 3 hours after fluid resuscitation to measure hemodynamic and metabolic shock indicators, inflammatory mediators, and thrombin-antithrombin complex formation. Lungs and kidneys were processed for organ injury scoring and immunohistochemical analysis to quantify presence of neutrophils. Results: Induction of trauma and hemorrhagic shock resulted in significant increases in thrombin-antithrombin complex, inflammatory markers, and lung and kidney injury scores. Compared to vehicle, dekaparin treatment did not affect induction, severity, or recovery of shock as indicated by hemodynamics, metabolic indicators of shock (lactate and base excess), or metrics of bleeding, including overall blood loss, resuscitation volume, or hematocrit. While LR-vehicle-resuscitated rodents exhibited increased lung and kidney injury, administration of dekaparin significantly reduced organ injury scores and was similar to organ protection conferred by FFP resuscitation. This was associated with a significant reduction in neutrophil infiltration in lungs and kidneys and reduced lung fibrin deposition among dekaparin-treated rats compared to vehicle. No differences in organ injury, neutrophil infiltrates, or fibrin staining between dekaparin and FFP groups were observed. Finally, dekaparin treatment attenuated induction of thrombin-antithrombin complex and inflammatory mediators in plasma following trauma and hemorrhagic shock. Conclusion: Anti-thromboinflammatory properties of a synthetic 3-O-sulfated heparan sulfate 12-mer, dekaparin, could provide therapeutic benefit for mitigating organ injury following major trauma and hemorrhagic shock.

Predicting Futility in Severely Injured Patients: Using Arrival Lab Values and Physiology to Support Evidence-Based Resource Stewardship.

BACKGROUND: The recent pandemic exposed a largely unrecognized threat to medical resources, including daily available blood products. Some of the most severely injured patients who arrive in extremis consume tremendous resources yet succumb shortly after arrival. We sought to identify cut points available early in the patient's resuscitation that predicted 100% mortality. STUDY DESIGN: Cut points were developed from a previously collected data set of all level 1 trauma patients admitted January 2010 to December 2016. Objective values available on or shortly after arrival were evaluated. Once generated, we then validated these variables against (1) a prospective data set November 2017 to October 2021 of severely injured patients and (2) a multicenter, randomized trial of hemorrhagic shock patients. Analyses were conducted using STATA 17.0 (College Station, TX), generating positive predictive value (PPV), negative predictive value, sensitivity, and specificity. RESULTS: The development data set consisted of 9,509 patients (17% mortality), with 2,137 (24%) and 680 (24%) in the two validation data sets. Several combinations of arrival vitals and labs had 100% PPV. Patients undergoing CPR in the field or on arrival (with subsequent return of spontaneous circulation) required lower fibrinolysis LY-30 (30%) than those with systolic blood pressures of ≤50 (30 to 50%), ≤70 (80 to 90%), and ≤90 mmHg (90%). Using a combination of these validated variables, the Suspension of Transfusions and Other Procedures (STOP) criteria were developed, with each element predicting 100% mortality, allowing physicians to cease further resuscitative efforts. CONCLUSIONS: The use of evidence-based STOP criteria provides cut points of futility to help guide early decisions for discontinuing aggressive treatment of severely injured patients arriving in extremis.

Antithrombin Activity Is Associated with Persistent Thromboinflammation and Mortality in Patients with Severe COVID-19 Illness.

INTRODUCTION: Severe COVID-19 illness can lead to thrombotic complications, organ failure, and death. Antithrombin (AT) regulates thromboinflammation and is a key component of chemical thromboprophylaxis. Our goal was to examine the link between AT activity and responsiveness to thromboprophylaxis, markers of hypercoagulability, and inflammation among severe COVID-19 patients. METHODS: This was a single-center, prospective observational study enrolling SARS-CoV-2-positive patients admitted to the intensive care unit on prophylactic enoxaparin. Blood was collected daily for 7 days to assess AT activity and anti-factor Xa levels. Patient demographics, outcomes, and hospital laboratory results were collected. Continuous variables were compared using Mann-Whitney tests, and categorical variables were compared using χ2 tests. Multivariable logistic regression was used to determine the association between AT activity and mortality. RESULTS: In 36 patients, 3 thromboembolic events occurred, and 18 (50%) patients died. Patients who died had higher fibrinogen, D-dimer, and C-reactive protein (CRP) levels and lower AT activity. Reduced AT activity was independently associated with mortality and correlated with both markers of hypercoagulability (D-dimer) and inflammation (CRP). CONCLUSION: Low AT activity is associated with mortality and persistent hypercoagulable and proinflammatory states in severe COVID-19 patients. The anti-thromboinflammatory properties of AT make it an appealing therapeutic target for future studies.

Alterations in heparan sulfate proteoglycan synthesis and sulfation and the impact on vascular endothelial function.

The glycocalyx attached to the apical surface of vascular endothelial cells is a rich network of proteoglycans, glycosaminoglycans, and glycoproteins with instrumental roles in vascular homeostasis. Given their molecular complexity and ability to interact with the intra- and extracellular environment, heparan sulfate proteoglycans uniquely contribute to the glycocalyx's role in regulating endothelial permeability, mechanosignaling, and ligand recognition by cognate cell surface receptors. Much attention has recently been devoted to the enzymatic shedding of heparan sulfate proteoglycans from the endothelial glycocalyx and its impact on vascular function. However, other molecular modifications to heparan sulfate proteoglycans are possible and may have equal or complementary clinical significance. In this narrative review, we focus on putative mechanisms driving non-proteolytic changes in heparan sulfate proteoglycan expression and alterations in the sulfation of heparan sulfate side chains within the endothelial glycocalyx. We then discuss how these specific changes to the endothelial glycocalyx impact endothelial cell function and highlight therapeutic strategies to target or potentially reverse these pathologic changes.

PLATELET FUNCTION IN TRAUMA: IS CURRENT TECHNOLOGY IN FUNCTION TESTING MISSING THE MARK IN INJURED PATIENTS?

ABSTRACT: Platelets are subcellular anucleate components of blood primarily responsible for initiating and maintaining hemostasis. After injury to a blood vessel, platelets can be activated via several pathways, resulting in changed shape, adherence to the injury site, aggregation to form a plug, degranulation to initiate activation in other nearby platelets, and acceleration of thrombin formation to convert fibrinogen to fibrin before contracting to strengthen the clot. Platelet function assays use agonists to induce and measure one or more of these processes to identify alterations in platelet function that increase the likelihood of bleeding or thrombotic events. In severe trauma, these assays have revealed that platelet dysfunction is strongly associated with poor clinical outcomes. However, to date, the mechanism(s) causing clinically significant platelet dysfunction remain poorly understood. We review the pros, cons, and evidence for use of many of the popular assays in trauma, discuss limitations of their use in this patient population, and present approaches that can be taken to develop improved functional assays capable of elucidating mechanisms of trauma-induced platelet dysfunction. Platelet dysfunction in trauma has been associated with need for transfusions and mortality; however, most of the current platelet function assays were not designed for evaluating trauma patients, and there are limited data regarding their use in this population. New or improved functional assays will help define the mechanisms by which platelet dysfunction occurs, as well as help optimize future treatment.

Endotheliopathy is Associated with a 24-hour Fibrinolysis Phenotype Described by Low TEG Lysis and High D-Dimer after Trauma: a Secondary Analysis of the PROPPR Study.

Objectives: Determine associations between biomarkers of endotheliopathy, 24-hour fibrinolysis phenotypes and clinical outcomes after trauma. Background: The vascular endothelium is a critical regulator of hemostasis and organ function. The relationship between markers of endotheliopathy and fibrinolysis following trauma has not been evaluated. Methods: We performed a secondary analysis of prospectively collected biomarker data in the Pragmatic Randomized Optimal Platelet and Plasma Ratios (PROPPR) randomized controlled trial. We stratified subjects by 24-hour thromboelastography (TEG) percent clot lysis (LY30) and plasma D-dimer (DD) levels and evaluated differences in endotheliopathy biomarkers and clinical outcomes between subjects with one of four 24-hour fibrinolysis phenotypes: LY30 0.9-2.9% (LY30norm), LY30 >2.9% (LY30high), LY30 <0.9% and low DD (LY30low+DDlow), and LY30 <0.9% and high DD (LY30low+DDhigh). Results: The analysis included 168 subjects with LY30norm, 32 with LY30high, 147 with LY30low+DDlow and 124 with LY30low+DDhigh. LY30low+DDhigh subjects had greater injury severity and a higher incidence of severe head injury, multiorgan failure (MOF), and mortality than the other phenotypes. All endotheliopathy biomarkers were significantly higher in the LY30low+DDhigh phenotype. Adjusting for injury severity, mechanism and head trauma, 24-hour angiopoietin-2 and soluble thrombomodulin were independently associated with the LY30low+DDhigh phenotype. Both endothelial biomarkers were discriminating for MOF. Subjects with thrombomodulin level >9.5 ng/mL and angiopoietin-2 level >3.6 ng/mL accounted for 64% of subjects who developed MOF. Conclusions: In a multicenter trauma cohort, subjects with a fibrinolysis phenotype characterized by low TEG lysis and elevated DD 24 hours after injury have significantly worse endotheliopathy and clinical outcomes. Our findings support mechanistic evaluations of the role of the endothelium in fibrinolysis dysregulation that may drive late-stage organ injury.

Association of Changes in Antithrombin Activity Over Time With Responsiveness to Enoxaparin Prophylaxis and Risk of Trauma-Related Venous Thromboembolism.

Importance: Venous thromboembolism (VTE) affects 2% to 20% of recovering trauma patients, despite aggressive prophylaxis with enoxaparin. Antithrombin is a primary circulating anticoagulant and crucial component of enoxaparin thromboprophylaxis. Approximately 20% of trauma patients present with antithrombin deficiency (antithrombin activity <80%). Objective: To examine time-dependent changes in antithrombin activity, responsiveness to enoxaparin, as measured by anti-factor Xa (anti-FXa) levels, and incidence of VTE after severe trauma and to assess the association of ex vivo antithrombin supplementation with patients' sensitivity to enoxaparin prophylaxis. Design, Setting, and Participants: This single-center, prospective cohort study was performed at a level 1 trauma center between January 7, 2019, and February 28, 2020. Adult trauma patients admitted to the trauma service at high risk for VTE, based on injury pattern and severity, were screened and enrolled. Patients who were older than 70 years, were pregnant, had a known immunologic or coagulation disorder, or were receiving prehospital anticoagulants were excluded. Exposures: Blood samples were collected on emergency department arrival and daily for the first 8 days of hospitalization. Main Outcomes and Measures: Patients' antithrombin activity and anti-FXa levels were measured by a coagulation analyzer, and thrombin generation was measured by calibrated automated thrombography. Responsiveness to enoxaparin was assessed by measuring anti-FXa levels 4 to 6 hours after the first daily enoxaparin dose and compared between patients who developed VTE and who did not. In addition, the associations of ex vivo supplementation of antithrombin with plasma anti-FXa levels were assessed. Results: Among 150 patients enrolled (median [IQR] age, 35 [27-53] years; 37 [24.7%] female and 113 [75.3%] male; 5 [3.3%] Asian, 32 [21.3%] Black, and 113 [75.3%] White; and 51 [34.0%] of Hispanic ethnicity), 28 (18.7%) developed VTE. Patients with VTE had significantly lower antithrombin activity on admission compared with patients without VTE (median [IQR], 91% [79%-104%] vs 100% [88%-112%]; P = .04), as well as lower antithrombin activity on hospital days 5 (median (IQR), 90% [83%-99%] vs 114% [99%-130%]; P = .011), 6 (median [IQR], 97% [81%-109%] vs 123% [104%-134%]; P = .003), 7 (median [IQR], 82% [74%-89%] vs 123% [110%-140%]; P < .001), and 8 (median [IQR], 99% [85%-100%] vs 123% [109%-146%]; P = .011). Anti-FXa levels were significantly lower in patients with VTE vs those without VTE at hospital day 4 (median [IQR], 0.10 [0.05-0.14] IU/mL vs 0.18 [0.13-0.23] IU/mL; P = .006), day 6 (median [IQR], 0.12 [0.08-0.14] IU/mL vs 0.22 [0.13-0.28] IU/mL; P = .02), and day 7 (median [IQR], 0.11 [0.08-0.12] IU/mL vs 0.21 [0.13, 0.28] IU/mL; P = .002). Multivariable analyses found that for every 10% decrease in antithrombin activity during the first 3 days, the risk of VTE increased 1.5-fold. Conclusions and Relevance: The results of this cohort study suggest that after severe trauma, antithrombin deficiency is common and contributes to enoxaparin resistance and VTE. Interventional studies are necessary to determine the efficacy of antithrombin supplementation in the reduction of VTE incidence.

Green Plasma Has a Superior Hemostatic Profile Compared With Standard Color Plasma.

BACKGROUND: Limitations in available donors have dramatically reduced plasma availability over the past several decades, concurrent with increasing demand for some types of plasma. Plasma from female donors who are pregnant or taking oral contraceptives often has a green appearance, which frequently results in these units being discarded. This pilot study aimed to evaluate the hemostatic potential of green compared to standard-color plasma. MATERIALS AND METHODS: Plasma from twelve blood group-matched female and twelve male donors was obtained from the local blood center. Six of the female and all of the male units of plasma had a normal appearance (STANDARD), while six of the female units were grossly green (GREEN). The hemostatic potential was evaluated by thrombelastography (TEG), calibrated automated thrombogram (CAT), and coagulation factor level measurements. Univariate analysis was performed using Wilcoxon Rank-Sum. RESULTS: GREEN plasma was more procoagulant for all TEG values (r-value, k-time, angle, mA) when compared to STANDARD plasma. Differences were also observed in coagulation factor levels, with GREEN plasma having higher than STANDARD (factors II; VII, IX; X, XI, Protein S, and plasminogen); conversely, GREEN plasma had a longer lag time in CAT. DISCUSSION: This pilot study demonstrates that female donors with green plasma have a superior hemostatic profile than standard plasma. GREEN plasma should be further investigated for its safety profile and hemostatic potential, so if it is found to be a safe and functionally non-inferior product, it should be actively re-introduced for transfusion in bleeding patients.