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.

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.

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.

The Impact of Rapid Infuser Use on the Platelet Count, Platelet Function, and Hemostatic Potential of Whole Blood.

BACKGROUND: Rapid infusion pumps employing filters, roller pumps, and heat exchangers for the administration of blood products are not approved for platelets or cryoprecipitate. This technology may decrease platelet count and degrade coagulation proteins. The effect of rapid infusers on the hemostatic potential of whole blood is unknown. METHODS: Five units of low titer O+ whole blood were obtained from anonymous donors. Each unit was subjected to infusion by five different techniques: (1) gravity infusion without a filter, (2) gravity infusion with a filter, (3) Belmont rapid infuser at 70 mL/min, (4) Belmont at 100 mL/min, and (5) pressurized infusion with a pneumatic pressure bag and filter. After infusion, platelet count, platelet function, thrombin generation, and hemostatic potential were measured for each aliquot. Infusion techniques were compared, using gravity infusion without a filter as the control. RESULTS: There was a significant decrease in platelet count from baseline (168,000) in the BELMONT70 (97,000) and BELMONT100 (94,000) groups (P < 0.05). However, there were no differences in platelet function (all P > 0.20). While there were no differences in thromboelastography parameters between control and infusion models (all P > 0.20), there were significant increases in thrombin generation parameters by CAT in both the BELMONT70 and BELMONT100 groups (all P < 0.05). CONCLUSIONS: The use of a rapid infuser decreases the platelet count of WB but does not decrease platelet function or overall hemostatic potential. In fact, thrombin generation and thrombin potential are actually increased. Rapid infusers are safe for the transfusion of WB.

Advances in the understanding of trauma-induced coagulopathy.

Ten percent of deaths worldwide are due to trauma, and it is the third most common cause of death in the United States. Despite a profound upregulation in procoagulant mechanisms, one-quarter of trauma patients present with laboratory-based evidence of trauma-induced coagulopathy (TIC), which is associated with poorer outcomes including increased mortality. The most common causes of death after trauma are hemorrhage and traumatic brain injury (TBI). The management of TIC has significant implications in both because many hemorrhagic deaths could be preventable, and TIC is associated with progression of intracranial injury after TBI. This review covers the most recent evidence and advances in our understanding of TIC, including the role of platelet dysfunction, endothelial activation, and fibrinolysis. Trauma induces a plethora of biochemical and physiologic changes, and despite numerous studies reporting differences in coagulation parameters between trauma patients and uninjured controls, it is unclear whether some of these differences may be "normal" after trauma. Comparisons between trauma patients with differing outcomes and use of animal studies have shed some light on this issue, but much of the data continue to be correlative with causative links lacking. In particular, there are little data linking the laboratory-based abnormalities with true clinically evident coagulopathic bleeding. For these reasons, TIC continues to be a significant diagnostic and therapeutic challenge.

Traumatic Endotheliopathy: A Prospective Observational Study of 424 Severely Injured Patients.

OBJECTIVE: Investigate and confirm the association between sympathoadrenal activation, endotheliopathy and poor outcome in trauma patients. BACKGROUND: The association between sympathoadrenal activation, endotheliopathy, and poor outcome in trauma has only been demonstrated in smaller patient cohorts and animal models but needs confirmation in a large independent patient cohort. METHODS: Prospective observational study of 424 trauma patients admitted to a level 1 Trauma Center. Admission plasma levels of catecholamines (adrenaline, noradrenaline) and biomarkers reflecting endothelial damage (syndecan-1, thrombomodulin, and sE-selectin) were measured and demography, injury type and severity, physiology, treatment, and mortality up till 28 days were recorded. RESULTS: Patients had a median ISS of 17 with 72% suffering from blunt injury. Adrenaline and noradrenaline correlated with syndecan-1 (r = 0.38, P < 0.001 and r = 0.23, P < 0.001, respectively) but adrenaline was the only independent predictor of syndecan-1 by multiple linear regression adjusted for age, injury severity score, Glascow Coma Scale, systolic blood pressure, base excess, platelet count, hemoglobin, prehospital plasma, and prehospital fluids (100 pg/mL higher adrenaline predicted 2.75 ng/mL higher syndecan-1, P < 0.001). By Cox analyses adjusted for age, sex, injury severity score, Glascow Coma Scale, base excess, platelet count and hemoglobin, adrenaline, and syndecan-1 were the only independent predictors of both <24-hours, 7-day and 28-day mortality (all P < 0.05). Furthermore, noradrenaline was an independent predictor of <24-hours mortality and thrombomodulin was an independent predictor of 7-day and 28-day mortality (all P < 0.05). CONCLUSIONS: We confirmed that sympathoadrenal activation was strongly and independently associated with endothelial glycocalyx and cell damage (ie, endotheliopathy) and furthermore that sympathoadrenal activation and endotheliopathy were independent predictors of mortality in trauma patients.

Impact of blood products on platelet function in patients with traumatic injuries: a translational study.

BACKGROUND: Reductions in platelet (PLT) count and function are associated with poor outcomes in trauma patients. We proposed to determine if patients expected to receive blood products have a decrease in PLT function higher than expected based on the reduction in PLT count, and if the reduction in function could be associated with the donor plasma/supernatant received. METHODS: PLT count and function were measured on admission to the emergency department and intensive care unit in severely injured patients expected to receive a transfusion. PLT function was measured by Multiplate aggregometry in response to five agonists. Function was corrected for alterations in count. In vitro studies were conducted in the blood of normal subjects to assess the effect of dilutions with AB donor plasma on PLT function. RESULTS: Forty-six patients were enrolled, with 87% requiring a transfusion. Median Injury Severity Score was 23 (13, 29) and mortality 15%. PLT count and function were decreased from emergency department to intensive care unit admission by 25% and 58%, respectively. Decreases in function persisted after adjustment for count. Patients requiring large volumes of blood products had reductions in function that were disproportionately greater. Reductions in PLT function were greatest after transfusion of PLTs. In in vitro studies with a 30% dilution by autologous plasma caused a relational reduction in function, whereas allogenic plasma resulted in greater decreases that were highly variable between donors. CONCLUSIONS: Within hours of injury a decrease in both PLT count and function occurs, that is aggravated with the administration of blood products, with transfusion of PLTs showing the greatest effect. The effect on PLT function of allogenic transfused plasma appears to be highly donor related.

Protease-Activated Receptor 1 Contributes to Angiotensin II-Induced Cardiovascular Remodeling and Inflammation.

BACKGROUND: Angiotensin II (Ang II) plays an important role in cardiovascular disease. It also leads to the activation of coagulation. The coagulation protease thrombin induces cellular responses by activating protease-activated receptor 1 (PAR-1). We investigated whether PAR-1 contributes to Ang II-induced cardiovascular remodeling and inflammation. METHODS AND RESULTS: PAR-1+/+ (wild-type; WT) and PAR-1-/- mice were infused with Ang II (600 ng/kg/min) for up to 4 weeks. In WT mice, this dose of Ang II did not cause a significant increase in blood pressure but it did cause pathological changes in both the aorta and the heart. Ang II infusion resulted in vascular remodeling of the aorta, demonstrated by a significant increase in medial wall thickening and perivascular fibrosis. Importantly, both parameters were significantly attenuated by PAR-1 deficiency. Furthermore, perivascular fibrosis around coronary vessels was reduced in Ang II-treated PAR-1-/- mice compared to WT mice. In addition, PAR-1 deficiency significantly attenuated Ang II induction of inflammatory cytokines and profibrotic genes in the aortas compared to WT mice. Finally, PAR-1 deficiency had no effect on Ang II-induced heart hypertrophy. However, the heart function measured by fractional shortening was less impaired in PAR-1-/- mice than in WT mice. CONCLUSION: Our data indicate that PAR-1 plays a significant role in cardiovascular remodeling mediated by a blood pressure-independent action of Ang II.

Endothelial glycocalyx shedding and vascular permeability in severely injured trauma patients.

BACKGROUND: The endothelial glycocalyx layer (EGL) is a key regulator of vascular permeability, cell adhesion, and inflammation. The EGL is primarily composed of syndecan-1, hyaluronic acid (HA), heparan sulfate (HS) and chondroitin sulfate (CS). While many studies have observed increased shedding of syndecan-1 during hemorrhagic shock, little is known about the shedding of other EGL components, and their effects on altered permeability and coagulation. We characterized shedding of all four primary components of the EGL, as well as the plasma's effect on permeability and thrombin generation in a cohort of trauma patients. METHODS: Plasma samples were collected from 5 healthy consented volunteers and 22 severely injured trauma patients upon admission to the emergency department. ELISA assays were performed to quantify shed HA, HS, CS and syndecan-1 in plasma. A colloid osmometer and Electric Cell-substrate Impedance Sensing (ECIS) system were used to measure plasma colloid osmotic pressure (COP) and cell permeability, respectively. Thrombin generation was measured using a calibrated automated thrombogram (CAT). Initial vital signs, routine laboratory values, and injury severity scores (ISS) were recorded. Non-parametric statistical tests were used to compare differences between groups. RESULTS: We observed increased shedding of all four proteins in trauma patient plasma compared to healthy controls: 31.7 vs. 21.2 U/L of CS, 175.8 vs. 121.9 ng/ml of HS, 946.7 vs. 618.6 ng/ml of HA and 245.8 vs. 31.6 ng/ml of syndecan-1 (all p<0.05). Patients with low plasma COP (≤16 mmHg) had significantly increased syndecan-1 and HA compared to those with normal COP, which corresponded to increased cell permeability via ECIS. CS and HS did not vary between COP groups. Lastly, patients with low COP displayed reduced peak thrombin generation of less than 250 nM on average (p<0.05). CONCLUSIONS: Glycocalyx components were shed more in trauma patients compared to healthy controls in this cohort. However, only syndecan-1 and HA shedding were significantly higher in patients with reduced plasma COP. Thrombin generation was impaired in patients with low plasma COP. These data suggest that low plasma COP correlates well to glycocalyx degradation and thrombin loss following trauma, which consequently affect permeability and coagulation.

Hypercoagulability after energy drink consumption.

BACKGROUND: Energy drink consumption in the United States has more than doubled over the last decade and has been implicated in cardiac arrhythmias, myocardial infarction, and even sudden cardiac death. We hypothesized that energy drink consumption may increase the risk of adverse cardiovascular events by increasing platelet aggregation, thereby resulting in a relatively hypercoagulable state and increased risk of thrombosis. METHODS: Thirty-two healthy volunteers aged 18-40 y were given 16 oz of bottled water or a standardized, sugar-free energy drink on two separate occasions, 1-wk apart. Beverages were consumed after an overnight fast over a 30-min period. Coagulation parameters and platelet function were measured before and 60 min after consumption using thrombelastography and impedance aggregometry. RESULTS: No statistically significant differences in coagulation were detected using kaolin or rapid thrombelastography. In addition, no differences in platelet aggregation were detected using ristocetin, collagen, thrombin receptor-activating peptide, or adenosine diphosphate-induced multiple impedance aggregometry. However, compared to water controls, energy drink consumption resulted in a significant increase in platelet aggregation via arachidonic acid-induced activation (area under the aggregation curve, 72.4 U versus 66.3 U; P = 0.018). CONCLUSIONS: Energy drinks are associated with increased platelet activity via arachidonic acid-induced platelet aggregation within 1 h of consumption. Although larger clinical studies are needed to further address the safety and health concerns of these drinks, the increased platelet response may provide a mechanism by which energy drinks increase the risk of adverse cardiovascular events.

Mechanisms of trauma-induced coagulopathy.

PURPOSE OF REVIEW: Hemorrhage is the leading cause of potentially preventable death following injury. Excessive and uncontrolled bleeding, commonly referred to as trauma-induced coagulopathy (TIC), affects a quarter of all trauma patients and is associated with substantial injuries, increased transfusion requirements, and poor outcomes. Recent data have contributed to our current understanding of the molecular mechanisms driving TIC. RECENT FINDINGS: The current literature offers evidence supporting proposed mechanisms that induce TIC, such as platelet dysfunction, endogenous anticoagulation, endothelial activation, fibrinogen modifications, and hyperfibrinolysis. However, the majority of these data are mere associations; causative data are slowly unfolding through the utilization of animal models of hemorrhagic shock coupled with prospective observational clinical studies. SUMMARY: As both clinical and basic science research expands our understanding of TIC, trauma patient care is improving substantially. Future studies should focus on the interplay between the coagulation pathways whose simultaneous or codependent dysregulation could offer the most advantageous points for intervention.

Tumor-derived tissue factor activates coagulation and enhances thrombosis in a mouse xenograft model of human pancreatic cancer.

Cancer patients often have an activated clotting system and are at increased risk for venous thrombosis. In the present study, we analyzed tissue factor (TF) expression in 4 different human pancreatic tumor cell lines for the purpose of producing derivative tumors in vivo. We found that 2 of the lines expressed TF and released TF-positive microparticles (MPs) into the culture medium. The majority of TF protein in the culture medium was associated with MPs. Only TF-positive cell lines activated coagulation in nude mice, and this activation was abolished by an anti-human TF Ab. Of the 2 TF-positive lines, only one produced detectable levels of human MP TF activity in the plasma when grown orthotopically in nude mice. Surprisingly, < 5% of human TF protein in plasma from tumor-bearing mice was associated with MPs. Mice with TF-positive tumors and elevated levels of circulating TF-positive MPs had increased thrombosis in a saphenous vein model. In contrast, we observed no difference in thrombus weight between tumor-bearing and control mice in an inferior vena cava stenosis model. The results of the present study using a xenograft mouse model suggest that tumor TF activates coagulation, whereas TF on circulating MPs may trigger venous thrombosis.

In vitro efficacy of RiaSTAP after rapid reconstitution.

BACKGROUND: Fibrinogen is the first coagulation factor to reach critical levels during hemorrhage. Consequently, reestablishing normal fibrinogen levels is necessary to achieve adequate hemostasis. Fibrinogen is supplemented through administration of fresh frozen plasma, cryoprecipitate, or human fibrinogen concentrate, RiaSTAP. RiaSTAP is potentially the most advantageous fibrinogen replacement product because it offers the highest fibrinogen concentration, lowest volume, and most consistent dose. Unfortunately, RiaSTAP is limited by a protocol reconstitution time of 15 min. Conversely, physicians in emergency settings frequently resort to a forceful and rapid reconstitution, which causes foaming and possible protein loss and/or damage. This study aims to address the in vitro effectiveness of protocol-reconstituted RiaSTAP versus rapidly reconstituted RiaSTAP versus cryoprecipitate. METHODS: Three fibrinogen treatments were prepared: protocol-reconstituted RiaSTAP, rapidly reconstituted RiaSTAP, and thawed cryoprecipitate. Each treatment was added in theoretical doses of 0-600 mg/dL to fibrinogen-depleted plasma (normal fibrinogen level is 150-450 mg/dL). Samples were generated in triplicate, and each sample was subjected to rapid thrombelastography and Clauss assays. The rapid thrombelastography assay measures the hemostatic potential of a blood and/or plasma sample. The maximum amplitude (MA) parameter indicates overall clot strength and is a reflection of fibrinogen efficacy. The Clauss assay measures the time to clot formation in response to a known concentration of thrombin, and the amount of functional fibrinogen is then determined from a standard curve. RESULTS: For all fibrinogen treatments, increasing fibrinogen dose resulted in an increase in MA. There was no significant difference in MA between both RiaSTAP reconstitutions (slope of RiaSTAP [protocol], 10.85 mm/[100 mg/dL] and slope of RiaSTAP [rapid], 10.54 mm/[100 mg/dL]). However, both protocol-reconstituted RiaSTAP and rapidly reconstituted RiaSTAP have higher MA values than cryoprecipitate in doses of ≥100 mg/dL. Moreover, each replicate of cryoprecipitate showed a higher variance in fibrinogen efficacy (coefficient of variance [CV] = 44.7%) at a fibrinogen dose of 300 mg/dL. RiaSTAP, however, showed a lower variance in fibrinogen efficacy for both reconstitutions (RiaSTAP [protocol], CV = 3.3% and RiaSTAP [rapid], CV = 2.7%), indicating a consistent fibrinogen dose. CONCLUSIONS: RiaSTAP (either reconstitution method) has greater hemostatic potential and less variability in fibrinogen concentration compared with cryoprecipitate. Rapidly reconstituted RiaSTAP does not compromise hemostatic potential and can be used to potentially facilitate hemostasis in rapidly bleeding patients.

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.

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.

Causal relationship between hyperfibrinogenemia, thrombosis, and resistance to thrombolysis in mice.

Epidemiologic studies have correlated elevated plasma fibrinogen (hyperfibrinogenemia) with risk of cardiovascular disease and arterial and venous thrombosis. However, it is unknown whether hyperfibrinogenemia is merely a biomarker of the proinflammatory disease state or is a causative mechanism in the etiology. We raised plasma fibrinogen levels in mice via intravenous infusion and induced thrombosis by ferric chloride application to the carotid artery (high shear) or saphenous vein (lower shear); hyperfibrinogenemia significantly shortened the time to occlusion in both models. Using immunohistochemistry, turbidity, confocal microscopy, and elastometry of clots produced in cell and tissue factor-initiated models of thrombosis, we show that hyperfibrinogenemia increased thrombus fibrin content, promoted faster fibrin formation, and increased fibrin network density, strength, and stability. Hyperfibrinogenemia also increased thrombus resistance to tenecteplase-induced thrombolysis in vivo. These data indicate that hyperfibrinogenemia directly promotes thrombosis and thrombolysis resistance and does so via enhanced fibrin formation and stability. These findings strongly suggest a causative role for hyperfibrinogenemia in acute thrombosis and have significant implications for thrombolytic therapy. Plasma fibrinogen levels may be used to identify patients at risk for thrombosis and inform thrombolytic administration for treating acute thrombosis/thromboembolism.

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.