Thrombin generation profiles as predictors of symptomatic venous thromboembolism after trauma: A prospective cohort study

Circulating Blood Biomarkers and Risk of Venous Thromboembolism in Cancer Patients: A Systematic Review and Meta-Analysis

BACKGROUND

 Cancer patients have an increased risk of venous thromboembolism (VTE). Currently, the availability of highly discriminatory prediction models for VTE in cancer patients is limited. The implementation of biomarkers in prediction models might lead to refined VTE risk prediction. In this systematic review and meta-analysis, we aimed to evaluate candidate biomarkers and their association with cancer-associated VTE.

METHODS

 We searched Medline, EMBASE, and Cochrane Central for studies that evaluated biomarkers in adult cancer patients from inception to September 2022. We included studies reporting on VTE after a cancer diagnosis with biomarker measurements performed at a defined time point. Median/mean differences (for continuous measures) and odds ratios (for dichotomous measures) with 95% confidence intervals were estimated and pooled using random-effects models.

RESULTS

 We included 113 studies in the systematic review. Of these, 50 studies were included in the meta-analysis. We identified two biomarkers at cancer diagnosis (factor VIII and time to peak thrombin), three biomarkers pre-chemotherapy (D-dimer, fibrinogen, and mean platelet volume), and one biomarker preoperatively (platelet count) that had significant median or mean differences. Additionally, we found that hemoglobin <100 g/L and white blood count >11 × 109/L were significantly associated with future VTE risk only when measured at cancer diagnosis. Pre-chemotherapy neutrophil-to-lymphocyte ratio ≥3 and preoperative platelet count ≥400 × 109/L were also found to be associated with future VTE risk.

CONCLUSION

 In conclusion, this study identified nine candidate blood biomarkers that may help in optimizing VTE prediction in cancer patients that should be further explored in future studies.

INHIBITORS OF INORGANIC POLYPHOSPHATE AND NUCLEIC ACIDS ATTENUATE IN VITRO THROMBIN GENERATION IN PLASMA FROM TRAUMA PATIENTS

ABSTRACT

Background: Inorganic polyphosphate (polyP) is a procoagulant polyanion. We assessed the impact of polyP inhibition on thrombin generation after trauma using the novel polyP antagonists, macromolecular polyanion inhibitor 8 (MPI 8), and universal heparin reversal agent 8 (UHRA-8). Methods: Plasma thrombin generation (calibrated automated thrombogram, CAT), in 56 trauma patients and 39 controls +/- MPI 8 and UHRA-8 (50 μg/mL), was expressed as lag time (LT, minutes), peak height (PH, nM), and time to peak (ttPeak, minutes), with change in LT (ΔLT) and change in ttPeak (ΔttPeak) quantified. Results expressed in median and quartiles [Q1, Q3], Wilcoxon matched-pairs testing, P < 0.05 significant. Results: Trauma patients had greater baseline PH than controls (182.9 [121.0, 255.2]; 120.5 [62.1, 174.8], P < 0.001). MPI 8 treatment prolonged LT and ttPeak in trauma (7.20 [5.88, 8.75]; 6.46 [5.45, 8.93], P = 0.020; 11.28 [8.96, 13.14]; 11.00 [8.95, 12.94], P = 0.029) and controls (7.67 [6.67, 10.50]; 6.33 [5.33, 8.00], P < 0.001; 13.33 [11.67, 15.33]; 11.67 [10.33, 13.33], P < 0.001). UHRA-8 treatment prolonged LT and ttPeak and decreased PH in trauma (9.09 [7.45, 11.33]; 6.46 [5.45, 8.93]; 14.02 [11.78, 17.08]; 11.00 [8.95, 12.94]; 117.4 [74.5, 178.6]; 182.9 [121.0, 255.2]) and controls (9.83 [8.00, 12.33]; 6.33 [5.33, 8.00]; 16.67 [14.33, 20.00]; 11.67 [10.33, 13.33]; 55.3 [30.2, 95.9]; 120.5 [62.1, 174.8]), all P < 0.001. Inhibitor effects were greater for controls (greater ΔLT and ΔttPeak for both inhibitors, P < 0.001). Conclusion: PolyP inhibition attenuates thrombin generation, though to a lesser degree in trauma than in controls, suggesting that polyP contributes to accelerated thrombin generation after trauma.

Venous Thromboembolic Events in Adult Trauma Patients Receiving Balanced Hemostatic Resuscitation (BHR): An Analysis of Their Incidence, Predictors, and Associated Mortality Rates at a Level 1 Trauma Center

Background and objective Studies assessing the incidence of venous thromboembolic (VTE) events in the setting of massive balanced transfusions and/or tranexamic acid (TXA) infusion have yielded varied outcomes. In light of this, we conducted this study to examine the incidence of VTEs in trauma patients requiring blood products, and to identify the risk factors for VTE and mortality in this population. Methods We performed a retrospective analysis of trauma patients admitted to our level 1 trauma center from January 2013 to September 2023. Clinical characteristics were compared between patients who developed VTE and those who did not. A regression analysis of potential variables associated with the development of VTEs and mortality was performed. Results Among 1305 patients (mean age: 42.4 ± 18.8 years) receiving blood products within the initial 24 hours, 4.3% (56 patients) developed a VTE. Patients with VTE experienced prolonged ICU and hospital stays and ventilation duration (p<0.001). They were also noted to have delayed initiation of VTE prophylaxis (104.2 vs. 50.3 hours, p<.001). Prolonged ventilation >7 days was the sole significant factor associated with VTE in multivariate regression analysis [odds ratio (OR): 6.2, p=0.004]. Early TXA administration (within four hours) showed a higher association with VTE than TXA within 24 hours (OR: 2.1, p=0.07 vs. OR 1.6, p=0.22). Massive transfusion was found to increase VTE risk (OR: 2.65, p<0.001). Severe head and neck (OR: 6.0, p=0.002) and chest (OR: 3.8, p=0.01) injuries were key predictors of mortality, while TXA was not significantly associated with mortality in the multivariate model. Conclusions Our study revealed an elevated risk of VTE in patients requiring massive transfusion protocol (MTP, ≥6 units). Early TXA administration was neither associated with increased VTE risk in MTP patients nor increased mortality risk. Strategies directed at reducing the risk of VTE in massively transfused patients while maintaining the survival benefits of balanced resuscitation and TXA need to be devised.

A murine multiple-injury model for the study of thromboinflammation

INTRODUCTION

Neutrophil extracellular traps (NETs) contribute to trauma-induced coagulopathy. We aimed to develop a murine multiple-injury model that induces thrombo-inflammatory response, that is, NETosis and accelerated thrombin generation.

METHODS

Wild-type male mice (n = 10, aged 8-12 weeks) underwent multiple injuries (gastrocnemius crush, femur fracture, and laparotomy) and were compared with an uninjured control group (n = 10). Mice were euthanized by cardiac puncture performed 3 hours after injury. Whole blood samples were immediately processed to platelet poor plasma for thrombin generation kinetics (calibrated automated thrombogram), myeloperoxidase (MPO), and von Willebrand factor quantification. Immunohistochemistry of lung tissue was performed to assess for citrullinated histone 3 (CitH3) and MPO. A NETosis cluster was defined as 3+ neutrophils staining for CitH3 at 400× magnification (CitH3 cluster). Data were presented either as mean (SD) or median (interquartile range) with p < 0.05 significant. Sham and trauma treated animals were compared by the two-sample Wilcoxon rank-sum test.

RESULTS

Animals subjected to multiple injuries had accelerated thrombin generation compared with controls with greater peak height (61.3 [41.2-73.2] vs. 28.4 [19.5-37.5] nM, p = 0.035) and shorter time to peak (3.37 [2.81-3.81] vs. 4.5 [4.08-4.75] minutes, p = 0.046). Markers of neutrophil activation were greater following multiple injuries than in controls (MPO, 961.1 [858.1-1116.8] vs. 481.3 [438.0-648.9] ng/mL; p = 0.004). NETosis, as evidenced by the aforementioned defined number of CitH3 clusters in the lung, was greater in multiple-injury animals than in controls (mean [SD], 3 [2.9] vs. 0.2 [0.7]; p = 0.009).

CONCLUSION

This is the first study to demonstrate that NETosis and accelerated thrombin generation can be induced using a murine multiple-injury model, as early as 3 hours following injury.

Rapid clearing CT-001 restored hemostasis in mice with coagulopathy induced by activated protein C

BACKGROUND

Activated protein C (APC) is one of the mechanisms contributing to coagulopathy, which is associated with high mortality. The counteraction of the APC pathway could help ameliorate bleeding. However, patients also transform frequently from a hemorrhagic state to a prothrombotic state at a later time. Therefore, a prohemostatic therapeutic intervention should take this thrombotic risk into consideration.

OBJECTIVES

CT-001 is a novel factor VIIa (FVIIa) with enhanced activity and desialylated N-glycans for rapid clearance. We assessed CT-001 clearance in multiple species and its ability to reverse APC-mediated coagulopathic blood loss.

METHODS

The N-glycans on CT-001 were characterized by liquid chromatography-mass spectrometry. Three species were used to evaluate the pharmacokinetics of the molecule. The potency and efficacy of CT-001 under APC pathway-induced coagulopathic conditions were assessed by coagulation assays and bleeding models.

RESULTS

The N-glycosylation sites of CT-001 had high occupancy of desialylated N-glycans. CT-001 exhibited 5 to 16 times higher plasma clearance in human tissue factor knockin mice, rats, and cynomolgus monkeys than wildtype FVIIa. CT-001 corrected the activated partial thromboplastin time and thrombin generation of coagulopathic plasma to normal in in vitro studies. In an APC-mediated saphenous vein bleeding model, 3 mg/kg of CT-001 reduced bleeding time in comparison with wildtype FVIIa. The correction of bleeding by CT-001 was also observed in a coagulopathic tail amputation severe hemorrhage mouse model. The efficacy of CT-001 is independent of the presence of tranexamic acid, and the combination of CT-001 and tranexamic acid does not lead to increased thrombogenicity.

CONCLUSION

CT-001 corrected APC pathway-mediated coagulopathic conditions in preclinical studies and could be a potentially safe and effective procoagulant agent for addressing APC-mediated bleeding.

Trauma-induced coagulopathy: What you need to know

ABSTRACT

Trauma-induced coagulopathy (TIC) is a global inflammatory state accompanied by coagulation derangements, acidemia, and hypothermia, which occurs after traumatic injury. It occurs in approximately 25% of severely injured patients, and its incidence is directly related to injury severity. The mechanism of TIC is multifaceted; proposed contributing factors include dysregulation of activated protein C, increased tPA, systemic endothelial activation, decreased fibrinogen, clotting factor consumption, and platelet dysfunction. Effects of TIC include systemic inflammation, coagulation derangements, acidemia, and hypothermia. Trauma-induced coagulopathy may be diagnosed by conventional coagulation tests including platelet count, Clauss assay, international normalized ratio, thrombin time, prothrombin time, and activated partial thromboplastin time; viscoelastic hemostatic assays such as thrombelastography and rotational thrombelastography; or a clinical scoring system known as the Trauma Induced Coagulopathy Clinical Score. Preventing TIC begins in the prehospital phase with early hemorrhage control, blood product resuscitation, and tranexamic acid therapy. Early administration of prothrombin complex concentrate is also being studied in the prehospital environment. The mainstays of TIC treatment include hemorrhage control, blood and component transfusions, and correction of abnormalities such as hypocalcemia, acidosis, and hypothermia.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

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.

Plasma thrombin generation kinetics vary by injury pattern and resuscitation characteristics in pediatric and young adult trauma patients

BACKGROUND

Thrombin generation kinetics are not well studied in children. This study aimed to assess how thrombin generation kinetics vary in pediatric and young adult (YA) trauma patients by clinical characteristics and injury pattern.

METHODS

Prospective cohort study where plasma samples were obtained from pediatric (ages 0-17 years) and YA (ages 18-21 years) trauma patients upon emergency department arrival. Thrombin generation (calibrated automated thrombogram [CAT]) was quantified as lag time (LT, minutes), peak height (PH, nM), time to peak (ttPeak, minutes), and endogenous thrombin potential (ETP, nM × minute). Results are expressed as median and quartiles [Q1, Q3] and compared using Wilcoxon rank sum testing with p < 0.05 considered significant.

RESULTS

We enrolled 47 pediatric (median age, 15 [14, 17] years, 78% male, 87% blunt, median Injury Severity Score, 12) and 49 YA (median age 20 [18, 21] years, 67% male, 84% blunt, median Injury Severity Score, 12) patients. Pediatric and YA patients had similar rates of operative intervention (51% vs. 57%), transfusion (25% vs. 20%), and traumatic brain injury (TBI) (53% vs. 49%). Pediatric patients who required an operation had accelerated initiation of thrombin generation, with shorter LT than those who did not (2.58 [2.33, 2.67]; 2.92 [2.54, 3.00], p = 0.034). Shorter LT (2.41 [2.22, 2.67]; 2.67 [2.53, 3.00]) and ttPeak (4.50 [4.23, 4.73]; 5.22 [4.69, 5.75], both p < 0.01) were noted in pediatric patients who required transfusion as compared with those who did not. The YA patients requiring transfusion had shorter LT (2.33 [2.19, 2.74]; 2.83 [2.67, 3.27]) and ttPeak (4.48 [4.33, 5.65]; 5.33 [4.85, 6.28] both p < 0.04) than those who were not transfused. Young adults with TBI had greater ETP than those without (1509 [1356, 1671]; 1284 [1154, 1471], p = 0.032).

CONCLUSION

Thrombin generation kinetics in pediatric trauma patients prior to intervention vary with need for operation and transfusion, while thrombin generation kinetics in young adult patients are influenced by TBI and need for operation or transfusion. This is a promising tool for assessing coagulopathy in young trauma patients.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level III.

Enhanced in vivo and ex vivo thrombin generation after lower-leg trauma, but not after knee arthroscopy

BACKGROUND

There is room for improvement of prevention of venous thromboembolism (VTE) after lower-leg cast application or knee arthroscopy. Information about the mechanism of clot formation in these patients may be useful to identify new prophylaxis targets. We aimed to study the effect of 1) lower-leg injury and 2) knee arthroscopy on thrombin generation.

METHODS

A cross-sectional study was conducted using plasma samples of POT-(K)CAST trials to measure ex vivo thrombin generation (Calibrated Automated Thrombography [CAT]) and plasma levels of prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin (TAT), fibrinopeptide A (FPA). Plasma was obtained shortly after lower-leg trauma or before and after (< 4 h) knee arthroscopy. Participants were randomly selected from those who did not develop VTE. For aim 1, samples of 88 patients with lower-leg injury were compared with 89 control samples (i.e., preoperative samples of arthroscopy patients). Linear regression was used to obtain mean differences (or ratios if ln-retransformed because of skewedness) adjusted for age, sex, body mass index, comorbidities. For aim 2, pre- and postoperative samples of 85 arthroscopy patients were compared, for which mean changes were obtained.

RESULTS

In patients with lower-leg injury (aim 1), endogenous thrombin potential, thrombin peak, velocity index, FPA and TAT were increased as compared with controls. In arthroscopy patients (aim 2), pre- and postoperative levels were similar for all parameters.

CONCLUSION

Lower-leg trauma increases thrombin generation both ex vivo and in vivo, in contrast to knee arthroscopy. This may imply that the pathogenesis of VTE is different in both situations.

Estradiol and Dihydrotestosterone Levels in COVID-19 Patients

OBJECTIVE

To determine differences in plasma sex hormone levels in male and female coronavirus disease 2019 (COVID-19) patients and healthy volunteers (HVs) because cell entry of severe acute respiratory syndrome coronavirus 2 occurs via the angiotensin-converting enzyme 2 receptor which is downregulated by 17β-estradiol.

PATIENTS AND METHODS

Citrated plasma samples were collected from 101 patients with COVID-19 upon presentation to the emergency department and from 40 HVs between November 1, 2020, and May 30, 2021. Plasma 17β-estradiol and 5α-dihydrotestosterone (DHT) levels were measured using enzyme-linked immunosorbent assay (pg/mL). Data are presented as median and quartiles (IQR). Wilcoxon rank sum test with a P value less than .05 was considered significant.

RESULTS

Patients with COVID-19 (median age, 49 years) included 51 males and 50 females (25 postmenopausal). Hospital admission was required for 58.8% of male patients (n = 30) and 48.0% of female patients (n = 24) (66.7% postmenopausal, n = 16) Healthy volunteers (median age, 41 years) included 20 males and 20 females (9 postmenopausal). Female patients with COVID-19 were found to have decreased 17β-estradiol levels (18.5 [IQR, 10.5-32.3] pg/mL; 41.4 [IQR, 15.5-111.0] pg/mL, P=.025), and lower 17β-estradiol to DHT ratios (0.073 [IQR, 0.052-0.159] pg/mL; 0.207 [IQR, 0.104-0.538] pg/mL, P=.015) than female HVs. Male patients with COVID-19 were found to have decreased DHT levels (302.8 [IQR, 249.9-470.8] pg/mL; 457.2 [IQR, 368.7-844.3] pg/mL, P=.005), compared with male HVs. Levels of DHT did not differ between female patients with COVID-19 and female HVs, whereas 17β-estradiol levels did not differ between male patients with COVID-19 and male HVs.

CONCLUSION

Sex hormone levels differ between patients with COVID-19 and HVs, with sex-specific patterns of hypogonadism in males and females. These alterations may be associated with disease development and severity.

TELOMERE LENGTH OF PERIPHERAL BLOOD MONONUCLEAR CELLS IS ASSOCIATED WITH DISCHARGE DISPOSITION IN OLDER TRAUMA PATIENTS

Introduction: Little is known regarding peripheral blood mononuclear cell telomere length (PBMC-TL) and response to traumatic injury. The objective of this study was to characterize the role of PBMC-TL in coagulation and clinical outcomes after injury. Methods: Plasma and buffy coats were prospectively collected from trauma patients and healthy volunteers. DNA was purified and PBMC-TL quantified by quantitative polymerase chain reaction. Thrombin generation kinetics were expressed as lag time (in minutes), peak height (in nanometers), time to peak (in minutes), and endogenous thrombin potential (in nM × min). Results are in median and quartiles [Q1, Q3]. P < 0.05 was considered significant (Wilcoxon rank sum testing). Results: Forty-two younger patients (21 [20, 22] years, 69% were male) and 39 older patients (62 [61, 64] years, 79% were male) were included. There was no significant difference in Clinical Frailty Scores between groups. Younger patients had longer total PBMC-TL (0.40 Mb [0.30, 0.49] vs. 0.29 Mb [0.23, 0.33], P < 0.001) and longer average PBMC-TL per chromosome (4.3 kb [3.3, 5.3] vs. 3.2 kb [2.5, 3.7], P < 0.001). When older patients were stratified by 50th percentile of PBMC-TL, there were no differences in thrombin generation; however, those with shorter telomeres were less likely to be discharged home (29% vs. 77%, P = 0.004). Older patients in the bottom quartile of PBMC-TL had shorter lag time (2.78 min [2.33, 3.00] vs. 3.33 min [3.24, 3.89], P = 0.030) and were less likely to be discharged home (22% vs. 90%, P = 0.006) than those in the top quartile of PBMC-TL. Multivariable logistic regression models revealed both increased age and shorter PBMC-TL to be independent predictors of discharge disposition other than home. Conclusion: In older trauma patients, shorter PBMC-TL is associated with accelerated initiation of thrombin generation and lower likelihood of being discharged to home.

Age-dependent thrombin generation predicts 30-day mortality and symptomatic thromboembolism after multiple trauma

Trauma-induced coagulopathy (TIC) is a risk factor for death and is associated with deviations in thrombin generation. TIC prevalence and thrombin levels increase with age. We assayed in vivo and ex vivo thrombin generation in injured patients (n = 418) to specifically investigate how age impacts thrombin generation in trauma and to address the prognostic ability of thrombin generation. Biomarkers of thrombin generation were elevated in young (< 40 years) and older (≥ 40 years) trauma patients. In vivo thrombin generation was associated with Injury Severity Score (ISS) and this association was stronger in young than older patients. In vivo thrombin generation decreased faster after trauma in the young than the older patients. Across age groups, in vivo thrombin generation separated patients dying/surviving within 30 days at a level comparable to the ISS score (AUC 0.80 vs. 0.82, p > 0.76). In vivo and ex vivo thrombin generation also predicted development of thromboembolic events within the first 30 days after the trauma (AUC 0.70-0.84). In conclusion, younger trauma patients mount a stronger and more dynamic in vivo thrombin response than older patients. Across age groups, in vivo thrombin generation has a strong ability to predict death and/or thromboembolic events 30 days after injury.

Haemostasis and Inflammatory Parameters as Potential Diagnostic Biomarkers for VTE in Trauma-Immobilized Patients

Venous thromboembolism (VTE), which encompasses deep venous thrombosis (DVT) and pulmonary embolism (PE), is a major public health concern due to its high incidences of morbidity and mortality. Patients who have experienced trauma with prolonged immobilization are at an increased risk of developing VTE. Plasma D-dimer levels have been known to be elevated in trauma patients, and they were closely correlated with the number of fractures. In other words, plasma D-dimer levels cannot be used as the only indicator of VTE in trauma cases. Given the limitations, further study is needed to explore other potential biomarkers for diagnosing VTE. To date, various established and novel VTE biomarkers have been studied in terms of their potential for predicting VTE, diagnostic performance, and improving clinical therapy for VTE. Therefore, this review aims to provide information regarding classic and essential haemostasis (including prothrombin time (PT), activated partial thromboplastin time (aPTT), D-dimer, fibrinogen, thrombin generation, protein C, protein S, antithrombin, tissue factor pathway inhibitor, and platelet count) and inflammatory biomarkers (C-reactive protein, erythrocyte sedimentation rate, and soluble P-selectin) as potential diagnostic biomarkers that can predict the risk of VTE development among trauma patients with prolonged immobilization. Thus, further advancement in risk stratification using these biomarkers would allow for a better diagnosis of patients with VTE, especially in areas with limited resources.

Characterization of 2 Different Prothrombin Complex Concentrates by Different Hemostatic Assays in an In Vitro Hemodilution Model

BACKGROUND

Viscoelastically guided coagulation factor concentrate-based algorithms for the treatment of trauma-induced coagulopathy include the administration of prothrombin complex concentrates (PCCs). However, the exact role of PCC preparations in this context is a matter of debate. Particularly, the ideal diagnostic trigger for their administration and potential differences between heparin-containing and heparin-free preparations remain unclear. We investigated the hypothesis that 2 different PCCs might have distinct influences on in vitro blood coagulation.

METHODS

We conducted a direct comparison of 2 commercially available PCC preparations (the heparin-containing Beriplex P/N and the heparin-free Cofact) in an in vitro hemodilution model. Sole fibrinogen substitution served as the control group. To characterize the hemostatic changes, we utilized conventional coagulation tests, a thrombin generation assay (TGA), and 2 different viscoelastic hemostatic assays (VHAs; ROTEM delta and ClotPro).

RESULTS

Irrespective of the diagnostic assay used, no significant differences between the 2 PCC groups were observed. Fibrinogen levels remained stable from the baseline throughout every dilution level. The control group already showed an increased endogenous thrombin potential (ETP; nM·L -1 ·min -1 ) at all dilution levels compared to baseline (baseline, 2829.4 (432.8); 40% dilution, 4211.7 (391.6); 60% dilution, 4290.9 (300.8); 80% dilution, 3861.4 (303.5); all P < .001). Spiking with both PCC preparations led to a further-pronounced thrombin elevation in comparison to the control group (ETP at 40% dilution, PCC1: 4913.3 [370.2], PCC2: 4988.1 [265.7]; 60% dilution, PCC1: 5174.5 [234.7], PCC2: 5390.4 [334.9]; 80% dilution, PCC1: 5253.8 [357.9], PCC2: 5392.6 [313.4]; all P < .001). Conventional coagulation tests did not mirror the TGA results. Despite increased thrombin generation, prothrombin time was significantly prolonged at all dilution levels for the control group, and both PCC groups exhibited significant prolongations at the 60% and 80% dilution levels (all P < .001) compared to baseline. Similarly, VHA did not depict the thrombin elevation. Furthermore, descriptive analyses revealed relevant differences between the 2 VHA devices, particularly at baseline.

CONCLUSIONS

Both PCC preparations (ie, irrespective of heparin content) induced significant elevation of thrombin generation, which was not depicted by conventional coagulation tests or VHA. Our in vitro results suggest that diagnostic assays routinely used to guide PCC administration might not adequately reflect thrombin generation in bleeding patients.

Does Antithrombotic Therapy Affect Outcomes in Major Trauma Patients? A Retrospective Cohort Study from a Tertiary Trauma Centre

Antithrombotic therapy may affect outcomes in major trauma but its role is not fully understood. We aimed to investigate adverse outcomes among those with and without antithrombotic treatment in major trauma. Material and methods: This is a retrospective study conducted at the Emergency Department (ED) of the University Hospital of Genoa, a tertiary trauma center, including all major trauma between January 2019 and December 2020. Adverse outcomes were reviewed among those without antithrombotic treatment (Group 0), on antiplatelet treatment (Group 1), and on anticoagulant treatment (Group 2). Results: We reviewed 349 electronic charts for full analysis. Group 0 were n = 310 (88.8%), Group 1 were n = 26 (7.4%), and Group 2 were n = 13 (3.7%). In-hospital death and ICU admission, respectively, were: n = 16 (5.6%) and n = 81 (26%) in Group 0, none and n = 6 (25%) in Group 1, and n = 2 (15.8%) and n = 4 (30.8%) in Group 2 (p = 0.123-p = 0.874). Altered INR (OR 5.2) and increasing D-dimer levels (AUC: 0.81) correlated to increased mortality. Discussion: Group 2 showed higher mortality than Group 0 and Group 1, however Group 2 had fewer active treatments. Of clotting factors, only altered INR and elevated D-dimer levels were significantly correlated to adverse outcomes. Conclusions: Anticoagulant but not antiplatelet treatment seems to produce the worst outcomes in major trauma.

Advances in the Management of Coagulopathy in Trauma: The Role of Viscoelastic Hemostatic Assays across All Phases of Trauma Care

Uncontrolled bleeding is the leading cause of preventable death following injury. Trauma-induced coagulopathy can manifest as diverse phenotypes ranging from hypocoagulability to hypercoagulability, which can change quickly during the acute phase of trauma care. The major advances in understanding coagulation over the past 25 years have resulted from the cell-based concept, emphasizing the key role of platelets and their interaction with the damaged endothelium. Consequently, conventional plasma-based coagulation testing is not accurate in predicting bleeding and does not provide an assessment of which blood products are indicated. Viscoelastic hemostatic assays (VHA), conducted in whole blood, have emerged as a superior method to guide goal-directed transfusion. The major change in resuscitation has been the shift from unbridled crystalloid loading to judicious balanced blood product administration. Furthermore, the recognition of the rapid changes from hypocoagulability to hypercoagulability has underscored the importance of ongoing surveillance beyond emergent surgery. While the benefits of VHA testing are maximized when used as early as possible, current technology limits use in the pre-hospital setting and the time to results compromises its utility in the emergency department. Thus, most of the reported experience with VHA in trauma is in the operating room and intensive care unit, where there is compelling data to support its value. This overview will address the current and potential role of VHA in the seriously injured patient, throughout the continuum of trauma management.

DNASE-MEDIATED DISSOLUTION OF NEUTROPHIL EXTRACELLULAR TRAPS ACCELERATES IN VITRO THROMBIN GENERATION KINETICS IN TRAUMA PATIENTS

ABSTRACT

Introduction: Neutrophil extracellular traps (NETs) trigger thrombin generation. We aimed to characterize the effects of deoxyribonuclease (DNAse) on NET components (cell-free DNA [cfDNA] and histones) and thrombin generation after trauma. Methods: Citrated plasma samples were collected from trauma patients and healthy volunteers. Thrombin generation (calibrated automated thrombogram) was measured as lag time (LT, in minutes), peak height (in nM), and time to peak thrombin generation (in minutes). Citrullinated histone 3 (CitH3) and 4 (CitH4) were measured by enzyme-linked immunosorbent assay; cfDNA by PicoGreen (all in nanograms per milliliter). Samples analyzed +/- DNAse (1,000 U/mL). Results expressed as median and quartiles [Q1, Q3], Wilcoxon testing, P < 0.05 significant. Results: We enrolled 46 patients (age, 48 [31, 67] years; 67% male) and 21 volunteers (age, 45 [28, 53] years; 43% male). Deoxyribonuclease treatment of trauma plasma led to shorter LT (3.11 [2.67, 3.52] min; 2.93 [2.67, 3.19] min), shorter time to peak thrombin generation (6.00 [5.30, 6.67] min; 5.48 [5.00, 6.00] min), greater peak height (273.7 [230.7, 300.5] nM; 288.7 [257.6, 319.2] nM), decreased cfDNA (576.9 [503.3, 803.1] ng/mL; 456.0 [393.5, 626.7] ng/mL), decreased CitH3 (4.54 [2.23, 10.01] ng/mL; 3.59 [1.93, 7.98] ng/mL), and increased H4 (1.30 [0.64, 6.36] ng/mL; 1.75 [0.83, 9.67] ng/mL), all P < 0.001. The effect of DNAse was greater on trauma patients as compared with volunteers for LT (ΔLT, -0.21 vs. -0.02 min, P = 0.007), cfDNA (ΔcfDNA -133.4 vs. -84.9 ng/mL, P < 0.001), and CitH3 (ΔCitH3, -0.65 vs. -0.11 ng/mL, P = 0.004). Conclusion: Deoxyribonuclease treatment accelerates thrombin generation kinetics in trauma patient samples as compared with healthy volunteers. These findings suggest that NETs may contribute to the hypercoagulable state observed in trauma patients.

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.

Performance and reference intervals of thrombin generation test: results from the Brazilian longitudinal study of adult health (ELSA-Brasil). A cross-sectional study

BACKGROUND

The thrombin generation test (TGT) has shown promise for investigation of hemorrhagic and thrombotic diseases. However, despite its potential, it still needs standardization. Moreover, few studies have established reference values for TGT parameters. In Brazil, these values have not yet been established.

OBJECTIVE

To determine TGT performance and reference intervals for TGT parameters in healthy individuals.

DESIGN AND SETTING

Cross-sectional study conducted among participants in the Brazilian Longitudinal Study of Adult Health (Estudo Longitudinal de Saúde do Adulto, ELSA-Brasil).

METHODS

The reference sample consisted of 620 healthy individuals. The calibrated automated thrombogram (CAT) method, under low and high tissue factor (TF) conditions, was used to assess thrombin generation. Test performance was analyzed using intra and interassay coefficients of variation (CV) and reference intervals were calculated using the nonparametric method proposed by the International Federation of Clinical Chemistry and the Clinical and Laboratory Standards Institute.

RESULTS

The intraassay CV ranged from 1.4% to 2.2% and the interassay CV, 6.8% to 14.7%. The reference intervals for TGT parameters under low and high TF conditions were, respectively: lagtime: 3.0-10.3 and 1.4-3.7 min; endogenous thrombin potential (ETP): 1134.6-2517.9 and 1413.6-2658.0 nM.min; normalized ETP: 0.6-1.3 and 0.7-1.4; peak: 103.2-397.7 and 256.4-479.0 nM; normalized peak: 0.3-1.3 and 0.7-1.2; and time-to-peak: 5.6-16.0 and 3.4-6.7 min. These parameters were categorized relative to sex.

CONCLUSION

TGT performance was adequate and the proposed reference intervals were similar to those of other studies. Our findings may be useful for consolidating the TGT, through contributing to its standardization and validation.

Second victim phenomenon after patient safety incidents among Korean nursing students: A cross-sectional study

BACKGROUND

Perfectionism in the medical field turns healthcare professionals into second victims of patient safety incidents. They suffer physically and psychologically, which makes them consider changing occupations. Nursing students may also have similar negative experiences during clinical practice.

OBJECTIVE

To describe the second victim phenomenon among nursing students after patient safety incidents during their clinical practice.

DESIGN

A descriptive cross-sectional study using an online questionnaire.

SETTING AND PARTICIPANTS

Fourth-year nursing students (n = 354) who encountered patient safety incidents directly or indirectly during clinical practice. Participants were recruited through convenience and snowball sampling methods using personal contacts, professional networks, and online platforms.

METHODS

The questionnaire addressed the characteristics of patient safety incidents, and physical and psychological responses after the most significant patient safety incident. Descriptive statistics and a chi-square test were performed for data analysis.

RESULTS

Of the participants, 22.6% were directly involved in patient safety incidents and 77.4% had indirectly encountered patient safety incidents, such as witnessing incidents with colleagues or other healthcare professionals. After patient safety incidents, of those, 67.8% experienced shock at the time of the incident, 47.2% feared experiencing a similar incident, and 28.2% were still affected although time had passed. Additionally, 26.3% reported experiencing long-term embitterment; of them, 7.3% were experiencing severe embitterment. Furthermore, 31.9% and 27.1% of the students experienced sleeping and eating difficulties, respectively, and these rates were higher when incidents were encountered directly rather than indirectly.

CONCLUSIONS

Nursing students may become second victims of patient safety incidents during clinical practice. Therefore, nursing education institutions need to develop comprehensive support strategies to help nursing students cope with experiencing the second victim phenomenon.

Biomarkers of thromboinflammation correlate to COVID-19 infection and admission status in emergency department patients

Background

COVID-19-associated coagulopathy is incompletely understood.

Objectives

To characterize thrombin generation, Von Willebrand Factor (VWF), neutrophil extracellular traps (NETs), and their role in COVID-19 risk stratification in the emergency department (ED).

Patients/methods

Plasma samples from 67 ED COVID-19 patients were compared to 38 healthy volunteers (HVs). Thrombin generation (calibrated automated thrombogram, CAT) was expressed as lag time (LT, min), peak height (PH, min), and time to peak (ttPeak, min). Citrullinated nucleosomes and histones were quantified with ELISA, VWF antigen and activity (IU/dL) through latex immunoassay, Factor VIII (IU/dL) through one-stage optical clot detection, and VWF multimers with Western blot densitometry. Wilcoxon testing and multivariable logistic regression were performed. Results presented as median [Q1, Q3]; p < 0.05 significant.

Results

COVID-19 patients had longer LT (4.00 [3.26, 4.67]; 2.95 [2.67, 3.10], p < 0.001) and ttPeak (7.33 [6.33, 8.04]; 6.45 [6.00, 7.50], p = 0.004), greater VWF antigen (212 [158, 275]; 110 [91, 128], p < 0.001) and Factor VIII levels (148 [106, 190]; 106 [86, 129], p < 0.001), with decreased high molecular weight multimers (Normalized multimer ratio 0.807 [0.759, 0.869]; 0.891 [0.858, 0.966], p < 0.001), than HVs. COVID-19 patients requiring admission from the ED had longer LT and ttPeak with greater VWF antigen and Factor VIII levels than those not admitted. Two and three variable models of CAT parameters and VWF correlated with COVID-19 and admission status (C-statistics 0.677 to 0.922).

Conclusions

Thrombin generation kinetics and VWF levels, independent of NETs, may have a role in predicting admission need for COVID-19 patients.

Potential value of the calibrated automated thrombogram in patients after a cerebral venous sinus thrombosis; an exploratory study

Background

Cerebral venous sinus thrombosis (CVST) is a relatively rare, but potentially lethal condition. In approximately 15% of the patients, the cause of CVST remains unclear. Conventional clotting tests such as prothrombin time and activated partial thromboplastin time are not sensitive enough to detect prothrombotic conditions nor mild haemostatic abnormalities. The calibrated automated thrombogram (CAT) is a physiological function test that might be able to detect minor aberrations in haemostasis. Therefore, we aimed to detect the presence of a prothrombotic state in patients who endured idiopathic CVST with the CAT assay.

Methods

Five adult patients with an idiopathic, radiologically proven CVST that had been admitted during the past 3 years were included in this study. The control group consisted of five age/gender matched healthy volunteers. Exclusion criteria were known haematological disorders, malignancy (current/past) or hormonal and anticoagulant therapy recipients. We obtained venous blood samples from all participants following cessation of anticoagulation. Using the CAT assay, we determined lag time, normalized endogenous thrombin potential (ETP), ETP reduction and normalized peak height. In addition, prothrombin concentrations were determined.

Results

We found no significant differences in lag time (4.7 min [4.5–4.9] vs 5.3 min [3.7–5.7], p = 0.691), normalized ETP (142% [124–148] vs 124% [88–138], p = 0.222), ETP reduction (29% [26–35] vs 28% [24–58], p > 0.999), and normalized peak height (155% [153–175] vs 137 [94–154], p = 0.056) between patients and their age/gender matched controls. In addition, prothrombin concentrations did not significantly differ between patients and controls (120% [105–132] vs 127% [87–139], p > 0.999).

Conclusion

Reasons for absent overt hypercoagulability within this study population may be the small patient sample, long time since the event (e.g. 3 years) and avoidance of acquired risk factors like oral contraception. Given the fact that CVST is a serious condition with a more than negligible risk of venous thrombosis event recurrence, exclusion of clinically relevant hypercoagulability remains a challenging topic to further study at the acute and later time points, particularly in patients with idiopathic CVST.

Thrombin Generation Following Severe Trauma: Mechanisms, Modulators, and Implications for Hemostasis and Thrombosis

ABSTRACT

Thrombin is the central coagulation enzyme that catalyzes the conversion of fibrinogen to form insoluble fibrin blood clots. In vivo, thrombin production results from the concerted effort of plasma enzymatic reactions with essential contributions from circulating and vessel wall cells. The relative amount of thrombin produced directly dictates the structure and stability of fibrin clots; therefore, sufficient thrombin generation is essential for normal hemostasis to occur. Examination of thrombin generation phenotypes among severely injury trauma patients reveals important relationships between the potential for generating thrombin and risks of bleeding and thrombotic complications. Thus, understanding determinants of thrombin generation following traumatic injury is of high clinical importance. This review will focus on patterns and mechanisms of thrombin generation in severely injured patients, the role of fluid resuscitation in modulating thrombin generation and implications for outcomes.

Neutrophil Extracellular Trap Formation and Syndecan-1 Shedding Are Increased After Trauma

BACKGROUND

Damage-associated molecular patterns (DAMPs) stimulate endothelial syndecan-1 shedding and neutrophil extracellular traps (NET) formation. The role of NETs in trauma and trauma-induced hypercoagulability is unknown. We hypothesized that trauma patients with accelerated thrombin generation would have increased NETosis and syndecan-1 levels.

METHODS

In this pilot study, we analyzed 50 citrated plasma samples from 30 trauma patients at 0 h (n = 22) and 6 h (n = 28) from time of injury (TOI) and 21 samples from healthy volunteers, for a total of 71 samples included in analysis. Thrombin generation was quantified using calibrated automated thrombogram (CAT) and reported as lag time (LT), peak height (PH), and time to peak (ttPeak). Nucleosome calibrated (H3NUC) and free histone standardized (H3Free) ELISAs were used to quantify NETs. Syndecan-1 levels were quantified by ELISA. Results are presented as median [interquartile range] and Spearman rank correlations.

RESULTS

Plasma levels of H3NUC were increased in trauma patients as compared with healthy volunteers both at 0 h (89.8 ng/mL [35.4, 180.3]; 18.1 ng/mL [7.8, 37.4], P = 0.002) and at 6 h (86.5 ng/mL [19.2, 612.6]; 18.1 ng/mL [7.8, 37.4], P = 0.003) from TOI. H3Free levels were increased in trauma patients at 0 h (5.74 ng/mL [3.19, 8.76]; 1.61 ng/mL [0.66, 3.50], P = 0.002) and 6 h (5.52 ng/mL [1.46, 11.37]; 1.61 ng/mL [0.66, 3.50], P = 0.006). Syndecan-1 levels were greater in trauma patients (4.53 ng/mL [3.28, 6.28]; 2.40 ng/mL [1.66, 3.20], P < 0.001) only at 6 h from TOI. H3Free and syndecan-1 levels positively correlated both at 0 h (0.376, P = 0.013) and 6 h (0.583, P < 0.001) from TOI. H3NUC levels and syndecan-1 levels were positively correlated at 6 h from TOI (0.293, P = 0.041). TtPeak correlated inversely to H3 NUC (-0.358, P = 0.012) and syndecan-1 levels (-0.298, P = 0.038) at 6 h from TOI.

CONCLUSIONS

Our pilot study demonstrates that trauma patients have increased NETosis, measured by H3NUC and H3Free levels, increased syndecan-1 shedding, and accelerated thrombin generation kinetics early after injury.

Euglobulin clot lysis time reveals a high frequency of fibrinolytic activation in trauma

Activation of the fibrinolytic system plays a central role in the host response to trauma. There is significant heterogeneity in the degree of fibrinolysis activation at baseline that is usually assessed by whole blood thromboelastography (TEG). Few studies have focused on plasma markers of fibrinolysis that could add novel insights into the frequency and mechanisms of fibrinolytic activation in trauma. Global fibrinolysis in plasma was assessed using a modified euglobulin clot lysis time (ECLT) assay in 171 major trauma patients and compared to commonly assessed analytes of fibrinolysis. The median ECLT in trauma patients was significantly shorter at 8.5 h (IQR, 1.3-19.5) compared to 19.9 h (9.8-22.6) in healthy controls (p < 0.0001). ECLT values ≤2.5th percentile of the reference range were present in 83 (48.5%) of trauma patients, suggesting increased fibrinolytic activation. Shortened ECLT values were associated with elevated plasmin-antiplasmin (PAP) complexes and free tissue plasminogen activator (tPA) levels in plasma. Sixteen (9.2%) individuals met the primary outcome for massive transfusion, here defined as the critical administration threshold (CAT) of 3 units of packed red cells in any 60-minute period within the first 24 h. In a univariate screen, plasma biomarkers associated with CAT included D-dimer (p < 0.001), PAP (p < 0.05), free tPA (p < 0.05) and ECLT (p < 0.05). We conclude that fibrinolytic activation, measured by ECLT, is present in a high proportion of trauma patients at presentation. The shortened ECLT is partially driven by high tPA levels and is associated with high levels of circulating PAP complexes. Further studies are needed to determine whether ECLT is an independent predictor of trauma outcomes.

Acquired antithrombin deficiency is a risk factor for venous thromboembolism after major trauma

BACKGROUND

Up to 30% of severely injured patients on prophylactic anticoagulation experience venous thromboembolism (VTE). Our previous work shows that acquired antithrombin (AT) deficiency [AT<80%] occurs in approximately 20% of trauma patients upon admission and drives poor responsiveness to enoxaparin. However, changes in AT over time and its association with VTE remain unknown. The aim of this study was to determine the relationship between acquired AT deficiency and VTE in severely injured patients.

METHODS

A secondary analysis of the Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) clinical trial was performed. Patients who died within 24 h of hemorrhage were excluded from analysis. Demographics, mechanism and severity of injury, transfusions volumes, and outcomes were compared between patients who did and did not develop VTE. Non-parametric statistical tests were used to compare patients with and without VTE. Logistic regression analyses were performed to identify predictors of VTE risk, controlling for AT deficiency (over first 72 h), age, gender, race, body mass index, study site, randomization group and injury severity. A Cox proportional hazards model was used to assess the contribution of AT deficiency to the risk of VTE, while censoring for early deaths.

RESULTS

Of the 680 patients enrolled in PROPPR, 101 died of hemorrhage. Of the remaining 579 patients, 86 (14.9%) developed VTE. The median time to VTE was 6 days (IQR 3, 13). No differences in demographics, injuries, or transfusion volumes were identified between VTE cases and controls. AT deficiency at 72 h post-admission was independently associated with VTE. Patients who experienced AT deficiency at 72 h had a 3.3 fold increased risk of VTE [p < 0.01; 95% CI 1.56, 6.98]. Lastly, patients who developed VTE had worse outcomes as displayed by significantly fewer hospital-free days compared to non-VTE patients [0 (0, 8) vs. 4 (0, 18), p < 0.01, respectively].

CONCLUSIONS

Acquired AT deficiency (AT<80%) is an important risk factor for VTE in severely injured patients. These data indicate that intervening, perhaps through AT supplementation, in the first three days after injury could mitigate the risk of VTE and improve patient outcomes.

Trauma-induced coagulopathy

Uncontrolled haemorrhage is a major preventable cause of death in patients with traumatic injury. Trauma-induced coagulopathy (TIC) describes abnormal coagulation processes that are attributable to trauma. In the early hours of TIC development, hypocoagulability is typically present, resulting in bleeding, whereas later TIC is characterized by a hypercoagulable state associated with venous thromboembolism and multiple organ failure. Several pathophysiological mechanisms underlie TIC; tissue injury and shock synergistically provoke endothelial, immune system, platelet and clotting activation, which are accentuated by the 'lethal triad' (coagulopathy, hypothermia and acidosis). Traumatic brain injury also has a distinct role in TIC. Haemostatic abnormalities include fibrinogen depletion, inadequate thrombin generation, impaired platelet function and dysregulated fibrinolysis. Laboratory diagnosis is based on coagulation abnormalities detected by conventional or viscoelastic haemostatic assays; however, it does not always match the clinical condition. Management priorities are stopping blood loss and reversing shock by restoring circulating blood volume, to prevent or reduce the risk of worsening TIC. Various blood products can be used in resuscitation; however, there is no international agreement on the optimal composition of transfusion components. Tranexamic acid is used in pre-hospital settings selectively in the USA and more widely in Europe and other locations. Survivors of TIC experience high rates of morbidity, which affects short-term and long-term quality of life and functional outcome.

Quantification of von Willebrand factor and ADAMTS-13 after traumatic injury: a pilot study

BACKGROUND

Von Willebrand factor (VWF) is an acute phase reactant synthesized in the megakaryocytes and endothelial cells. VWF forms ultra-large multimers (ULVWF) which are cleaved by the metalloprotease ADAMTS-13, preventing spontaneous VWF-platelet interaction. After trauma, ULVWF is released into circulation as part of the acute phase reaction. We hypothesized that trauma patients would have increased levels of VWF and decreased levels of ADAMTS-13 and that these patients would have accelerated thrombin generation.

METHODS

We assessed plasma concentrations of VWF antigen and ADAMTS-13 antigen, the Rapid Enzyme Assays for Autoimmune Diseases (REAADS) activity of VWF, which measure exposure of the platelet-binding A1 domain, and thrombin generation kinetics in 50 samples from 30 trauma patients and an additional 21 samples from volunteers. Samples were analyzed at 0 to 2 hours and at 6 hours from the time of injury. Data are presented as median (IQR) and Kruskal-Wallis test was performed between trauma patients and volunteers at both time points.

RESULTS

REAADS activity was greater in trauma patients than volunteers both at 0 to 2 hours (190.0 (132.0-264.0) vs. 92.0 (71.0-114.0), p<0.002) and at 6 hours (167.5 (108.0-312.5.0) vs. 92.0 (71.0-114.0), p<0.001). ADAMTS-13 antigen levels were also decreased in trauma patients both at 0 to 2 hours (0.84 (0.51-0.94) vs. 1.00 (0.89-1.09), p=0.010) and at 6 hours (0.653 (0.531-0.821) vs. 1.00 (0.89-1.09), p<0.001). Trauma patients had accelerated thrombin generation kinetics, with greater peak height and shorter time to peak than healthy volunteers at both time points.

DISCUSSION

Trauma patients have increased exposure of the VWF A1 domain and decreased levels of ADAMTS-13 compared with healthy volunteers. This suggests that the VWF burst after trauma may exceed the proteolytic capacity of ADAMTS-13, allowing circulating ULVWF multimers to bind platelets, potentially contributing to trauma-induced coagulopathy.

LEVEL OF EVIDENCE

Prospective case cohort study.

Thrombin Generation Kinetics are Predictive of Rapid Transfusion in Trauma Patients Meeting Critical Administration Threshold

INTRODUCTION

We hypothesize that a patient (pt) with accelerated thrombin generation, time to peak height (ttPeak), will have a greater odds of meeting critical administration threshold (CAT) criteria (> 3 packed red blood cell [pRBC] transfusions [Tx] per 60 min interval), within the first 24 h after injury, independent of international normalized ratio (INR).

METHODS

In a prospective cohort study, trauma patients were enrolled over a 4.5-year period and serial blood samples collected at various time points. We retrospectively stratified pts into three categories: CAT+, CAT- but receiving some pRBC Tx, receiving no Tx within the first 24 h. Blood collected prior to Tx was analyzed for thrombin generation parameters and prothrombin time (PT)/INR.

RESULTS

A total of 484 trauma pts were analyzed: injury severity score = 13 [7,22], age = 48 [28, 64] years, and 73% male. Fifty pts met criteria for CAT+, 64 pts CAT-, and 370 received no Tx. Risk factors for meeting CAT+: decreased arrival systolic blood pressure (OR 2.82 [2.17, 3.67]), increased INR (OR 2.09, [1.66, 2.62]) and decreased time to peak OR 2.27 [1.74, 2.95]). These variables remained independently associated with increased risk of requiring Tx in a multivariable logistic model, after adjusting for sex and trauma type.

CONCLUSIONS

Pts in hemorrhagic shock, who meet CAT+ criteria, are characterized by accelerated thrombin generation. In our multivariable analysis, both ttPeak and PT/INR have a complementary role in predicting those injured patients who will require a high rate of Tx.

Exploring the utility of a novel point-of-care whole blood thrombin generation assay following trauma: A pilot study

INTRODUCTION

Plasma thrombin generation kinetics as measured by the calibrated automated thrombogram (CAT) assay is a predictor of symptomatic venous thromboembolism after trauma. We hypothesized that data from a new prototype assay for measurement of thrombin generation kinetics in fresh whole blood (near patient testing of thrombin generation), will correlate with the standard CAT assay in the same patients, making it a potential tool in the future care of trauma patients.

METHODS

Patients were enrolled from June 2018 to February 2020. Within 12 hours of injury, blood samples were collected simultaneously for both assays. Variables compared and correlated between assays were lag time, peak height, time to peak, and endogenous thrombin potential. Data are presented as median with interquartile range (IQR). Spearman and Pearson correlations were estimated and tested between both assays; a P value of <0.05 was considered to be significant.

RESULTS

A total of 64 trauma patients had samples analyzed: injury severity score = 17 (IQR), 10-26], hospital length of stay = 7.5 (IQR), 2-18) days, age = 52 (IQR, 35-63) years, 71.9% male, and 42.2% of patients received a transfusion within 24 hours of injury. Thrombin generation parameters between plasma and whole blood were compared and found that all parameters of the two assays correlate in trauma patients.

CONCLUSION

In this pilot study, we have found that a novel point-of-care whole blood thrombin generation assay yields results with modest but statistically significant correlations to those of a standard plasma thrombin generation assay. This finding supports studying this device in a larger, adequately powered study.

Whole Blood Thrombin Generation in Severely Injured Patients Requiring Massive Transfusion

BACKGROUND

Despite the prevalence of hypocoagulability after injury, the majority of trauma patients paradoxically present with elevated thrombin generation (TG). Although several studies have examined plasma TG post injury, this has not been assessed in whole blood. We hypothesize that whole blood TG is lower in hypocoagulopathy, and TG effectively predicts massive transfusion (MT).

STUDY DESIGN

Blood was collected from trauma activation patients at an urban Level I trauma center. Whole blood TG was performed with a prototype point-of-care device. Whole blood TG values in healthy volunteers were compared with trauma patients, and TG values were examined in trauma patients with shock and MT requirement.

RESULTS

Overall, 118 patients were included. Compared with healthy volunteers, trauma patients overall presented with more robust TG; however, those arriving in shock (n = 23) had a depressed TG, with significantly lower peak thrombin (88.3 vs 133.0 nM; p = 0.01) and slower maximum rate of TG (27.4 vs 48.3 nM/min; p = 0.04). Patients who required MT (n = 26) had significantly decreased TG, with a longer lag time (median 4.8 vs 3.9 minutes, p = 0.04), decreased peak thrombin (median 71.4 vs 124.2 nM; p = 0.0003), and lower maximum rate of TG (median 15.8 vs 39.4 nM/min; p = 0.01). Area under the receiver operating characteristics (AUROC) analysis revealed lag time (AUROC 0.6), peak thrombin (AUROC 0.7), and maximum rate of TG (AUROC 0.7) predict early MT.

CONCLUSIONS

These data challenge the prevailing bias that all trauma patients present with elevated TG and highlight that deficient thrombin contributes to the hypocoagulopathic phenotype of trauma-induced coagulopathy. In addition, whole blood TG predicts MT, suggesting point-of-care whole blood TG can be a useful tool for diagnostic and therapeutic strategies in trauma.

Sufficient Thrombin Generation Despite 95% Hemodilution: An In Vitro Experimental Study

Guidelines for the treatment of severe bleeding comprise viscoelastic-test-guided use of coagulation factor concentrates as part of their recommendations. The aim of this study is to investigate the effects of substituting fibrinogen, prothrombin complex concentrate, and a combination of both on conventional coagulation tests, viscoelastic test results, and thrombin generation. Blood was drawn from seven healthy volunteers to obtain platelet-free plasma, which later was diluted by replacing 40%, 60%, 80%, 90%, 95%, and 99% with a crystalloid solution. The diluted samples were spiked with fibrinogen concentrate, prothrombin complex concentrate, a combination of both, or a corresponding amount of crystalloid solution. Up to a dilution level of 95%, viscoelastically determined clotting time was significantly shorter in the group substituted with fibrinogen only in comparison with the additional use of prothrombin complex concentrate. Clot firmness and endogenous thrombin potential remained at relatively stable values up to a dilution level of 95% with the substitution of fibrinogen but not prothrombin complex concentrate. Substitution of prothrombin complex concentrate led to an excessive overshoot of thrombin generation. The results of our study question currently propagated treatment algorithms for bleeding patients that include the use of prothrombin complex concentrate for patients without former intake of oral anticoagulants. Even in severely bleeding patients, thrombin generation might be sufficient to achieve adequate hemostasis.

Trauma-Induced Coagulopathy and Massive Bleeding: Current Hemostatic Concepts and Treatment Strategies

Hemorrhage after trauma remains a significant cause of preventable death. Trauma-induced coagulopathy (TIC) at the time of hospital admission is associated with an impaired outcome. Rather than a universal phenotype, TIC represents a complex hemostatic disorder, and standard coagulation tests are not designed to adequately reflect the complexity of TIC. Viscoelastic testing (VET) has gained increasing interest for the characterization of TIC because it provides a more comprehensive depiction of the coagulation process. Thus, VET has been established as a point-of-care-available hemostatic monitoring tool in many trauma centers. Damage-control resuscitation and early administration of tranexamic acid provide the basis for treating TIC. To improve survival, ratio-driven massive transfusion protocols favoring early and high-dose plasma transfusion have been implemented in many trauma centers around the world. Although plasma contains all coagulation factors and inhibitors, only high-volume plasma transfusion allows for adequate substitution of lacking coagulation proteins. However, high-volume plasma transfusion has been associated with several relevant risks. In some European trauma facilities, a more individualized hemostatic therapy concept has been implemented. The hemostatic profile of the bleeding patient is evaluated by VET. Subsequently, goal-directed hemostatic therapy is primarily based on coagulation factor concentrates such as fibrinogen concentrate or prothrombin complex concentrate. However, a clear difference in survival benefit between these two treatment strategies has not yet been shown. This concise review aims to summarize current evidence for different diagnostic and therapeutic strategies in patients with TIC.

Supplementation with antithrombin III ex vivo optimizes enoxaparin responses in critically injured patients

BACKGROUND

The high incidence of venous thromboembolism (VTE) following trauma persists in spite of aggressive thromboprophylaxis strategies. Approximately half of VTE patients do not achieve the recommended anti-FXa response to enoxaparin anticoagulation (0.1-0.4 IU/mL), however, research to explain or correct this phenomenon is lacking. We hypothesized that antithrombin III (AT) deficiency is associated with poor enoxaparin responsiveness in trauma patients that develop VTE which can be reversed through supplementation with AT.

METHODS AND FINDINGS

A retrospective cohort study was performed on plasma collected from trauma patients who did and did not develop pulmonary embolism (PE) as well as healthy volunteers. AT levels, thrombin generation, and anti-FXa levels were measured in the collected plasma at baseline and in response to supplementation with AT concentrate at 120-200% or plasma (30% volume). A total of 54 PE patients and 46 non-PE patients were enrolled in this study for analysis. Compared to healthy volunteers, trauma patients had lower levels of AT, elevated thrombin generation, and lower anti-FXa levels in response to enoxaparin. Moreover, thrombin generation was higher and responses to enoxaparin were lower in patients who developed PE compared to those who did not develop PE. We found that supplementation with AT, but not plasma, increased AT levels and improved enoxaparin-mediated inhibition of thrombin generation.

CONCLUSIONS

Supplementation with AT may provide a novel adjunct therapy to increase the effectiveness of enoxaparin thromboprophylaxis and reduce the incidence of VTE in the trauma population.

New considerations on pathways involved in acute traumatic coagulopathy: the thrombin generation paradox

Abstract

Background

An acute traumatic coagulopathy (ATC) is observed in about one third of severely traumatized patients. This early, specific, and endogenous disorder is triggered by the association of trauma and hemorrhage. The early phase of this condition is characterized by the expression of a bleeding phenotype leading to hemorrhagic shock and the late phase by a prothrombotic profile leading to multiple organ failure. The physiopathology of this phenomenon is still poorly understood. Hypotheses of disseminated intravascular coagulation, activated protein C-mediated fibrinolysis, fibrinogen consumption, and platelet functional impairment were developed by previous authors and continue to be debated. The objective of this study was to observe general hemostasis disorders in case of ATC to confront these hypotheses.

Method

Four groups of 15 rats were compared: C, control; T, trauma; H, hemorrhage; and TH, trauma and hemorrhage. Blood samples were drawn at baseline and 90 min. Thrombin generation tests, platelet aggregometry, and standard hemostasis tests were performed.

Results

Significant differences were observed between the baseline and TH groups for aPTT (17.9 ± 0.8 s vs 24.3 ± 1.4 s, p < 0.001, mean ± SEM), MAP (79.7 ± 1.3 mmHg vs 43.8 ± 1.3 mmHg, p < 0.001, mean ± SEM), and hemoglobin (16.5 ± 0.1 g/dL vs 14.1 ± 0.3 g/dL, p < 0.001, mean ± SEM), indicating the presence of an hemorrhagic shock due to ATC. Compared to all other groups, coagulation factor activities were decreased in the TH group, but endogenous thrombin potential was (paradoxically) higher than in group C (312 ± 17 nM/min vs. 228 ± 23 nM/min; p = 0.016; mean ± SEM). We also observed a subtle decrease in platelet count and function in case of ATC and retrieved an inversed linear relationship between fibrinogen concentration and aPTT (intercept, 26.53 ± 3.16; coefficient, − 3.40 ± 1.26; adjusted R²: 0.1878; p = 0.0123).

Conclusions

The clinical-biological profile that we observed, combining normal thrombin generation, fibrinogen depletion, and a hemorrhagic phenotype, reinforced the hypothesis of activated protein C mediated-fibrinolysis. The key role of fibrinogen, but not of the platelets, was confirmed in this study. The paradoxical preservation of thrombin generation suggests a protective mechanism mediated by rhabdomyolysis in case of major trauma. Based on these results, we propose a new conception concerning the pathophysiology of ATC.

Whole blood thrombin generation is distinct from plasma thrombin generation in healthy volunteers and after severe injury

BACKGROUND

Plasma thrombin generation has been used to characterize trauma-induced coagulopathy, but description of whole blood thrombin generation is lacking. This study aimed to evaluate plasma and whole blood thrombin generation in healthy volunteers and trauma patients. We hypothesized that (1) plasma and whole blood thrombin generation are distinct, (2) whole blood thrombin generation is more pronounced in trauma patients than in healthy volunteers, and (3) thrombin generation correlates with clinical coagulation assays.

METHODS

Blood was collected from healthy volunteers and trauma patients at a single, level-1 trauma center. Whole blood thrombin generation was assessed with a prototype point-of-care whole blood thrombin generation device, and plasma thrombin generation was measured with a calibrated automated thrombogram analogue. Plasma and whole blood thrombin generation were compared and correlated with international normalized ratio and thrombelastography.

RESULTS

Overall, 10 healthy volunteers (average age 30, 50% men) were included and 58 trauma patients (average age 34, 76% men, 55% blunt mechanism, and with a median new injury severity score of 17) were included. Plasma and whole blood thrombin generation differed with more robust thrombin generation in plasma. Trauma patients had a significantly increased whole blood thrombin generation compared with healthy volunteers]. Plasma thrombin generation correlated with international normalized ratio, whereas whole blood thrombin generation did not correlate with thrombelastography.

CONCLUSION

Plasma and whole blood thrombin generation are distinct, highlighting the need to perform standardized assays to better understand their correlation and to assess how whole blood thrombin generation confers differential outcomes in trauma.

Response to Letter to the Editor submitted by Dr. Wada and Dr. Yamakawa re: Trauma-induced coagulopathy: The past, present, and future

It is with equal appreciation and enthusiasm that we have the opportunity to participate in these valuable scientific discussions with our respected colleagues Dr. Wada and Dr. Yamakawa, as we did with Dr. Gando and Dr. Otomo on their analogous disseminated-intravascular coagulation (DIC)-centric views of trauma-induced coagulopathy (TIC). We welcome and appreciate Drs Wada and Yamakawa’s expounded descriptions on their areas of their expertise specific to the critical thrombin-specific biologies. We find their additions valuable to the overall framing of the state of the science and controversies that exists in TIC investigations. However, we continue to support that it would be erroneous to continue to force an inflexible view of the complex biology of TIC, thereby failing to acknowledge the various competing mechanisms and mediators described throughout the literature, including the sometimes contradictory biomarker phenotypes that are ‘impaired’ in TIC. In addition, much of our following response to Drs Wada and Yamakawa’s letter will involve referring back to what was already addressed within the manuscript that appears to have been overlooked. However, of absolute importance, we would like to stress that TIC remains open science should therefore be regarded with open minds and without siloed opinions.

A label-free electrochemical aptasensor based on magnetic biocomposites with Pb2+-dependent DNAzyme for the detection of thrombin

Herein, a novel magnetic biocomposite (Fe₃O₄@Au-S1/S2) was applied to analyze thrombin. The Fe₃O₄@Au-S1/S2 consisted of Fe₃O₄@Au nanoparticles (Fe₃O₄@Au NPs) as carriers for magnetic separation and magnetic field-induced self-assembly, thiolated complementary strand (S1) anchored based on Au-S bond and thrombin binding aptamer (S2) as a recognition element. As a redox indicator, methylene blue (MB) can be adsorbed to DNA anchored on the surface of Fe₃O₄@Au NPs by electro-static interaction. In the absence of thrombin, MB were adsorbed on double-stranded DNA (S1/S2) which anchored on Fe₃O₄@Au NPs and a high electrochemical signal of MB was recorded by Differential pulse voltammetry. Conversely, the complementary strand (S1) exposed after thrombin competitively bonded with aptamer. The introduction of Pb²⁺-dependent DNAzyme (S3) split S1 at specific rA site, resulting in the significantly decreased adsorption capacity of MB. Thus, the thrombin detection could be recorded by monitoring the electrochemical signal reduction of MB through incubation of thrombin with S3. This method exhibited a high sensitivity toward thrombin with a broad linear range from 5 pmol L^-1 to 5 nmol L^-1 and a limit of detection of 1.8 pmol L^-1.

Deep vein thrombosis and venous thromboembolism in trauma

PURPOSE OF REVIEW

Deep vein thrombosis (DVT) and pulmonary embolus are major causes of hospital-related morbidity and mortality, and are recognized as complications in patients with traumatic injury. Despite the significant morbidity and mortality associated with DVTs, prophylaxis and treatment are still not well understood and remain the subject of research and debate.

RECENT FINDINGS

Elements of the patient's history and physical examination, along with thromboelastography, can be used to predict patients who are at greatest risk of DVT and venous thromboembolism (VTE). Novel assays and biomarkers hold promise for more accurate evaluation of coagulation status. Patients with traumatic injury are routinely treated with either mechanical or pharmacological treatments to prevent DVT, and a growing body of evidence suggests that DVT prophylaxis should be initiated as early as possible in a patient's hospital course.

SUMMARY

In trauma patients with traumatic injury, early identification and targeted VTE prophylaxis in trauma patients may prevent this life-threatening complication.

Discovery of novel plasma biomarkers for future incident venous thromboembolism by untargeted synchronous precursor selection mass spectrometry proteomics

Essentials Discovery of predictive biomarkers of venous thromboembolism (VTE) may aid risk stratification. A case-control study where plasma was sampled before the occurrence of VTE was established. We generated untargeted plasma proteomic profiles of 200 individuals by use of mass spectrometry. Assessment of the biomarker potential of 501 proteins yielded 46 biomarker candidates.

ABSTRACT

Background Prophylactic anticoagulant treatment may substantially reduce the incidence of venous thromboembolism (VTE) but entails considerable risk of severe bleeding. Identification of individuals at high risk of VTE through the use of predictive biomarkers is desirable in order to achieve a favorable benefit-to-harm ratio. Objective We aimed to identify predictive protein biomarker candidates of VTE. Methods We performed a case-control study of 200 individuals that participated in the Tromsø Study, a population-based cohort, where blood samples were collected before the VTE events occurred. Untargeted tandem mass tag-synchronous precursor selection-mass spectrometry (TMT-SPS-MS3)-based proteomic profiling was used to study the plasma proteomes of each individual. Results Of the 501 proteins detected in a sufficient number of samples to allow multivariate analysis, 46 proteins were associated with VTE case-control status with P-values below the 0.05 significance threshold. The strongest predictive biomarker candidates, assessed by statistical significance, were transthyretin, vitamin K-dependent protein Z and protein/nucleic acid deglycase DJ-1. Conclusions Our untargeted approach of plasma proteome profiling revealed novel predictive biomarker candidates of VTE and confirmed previously reported candidates, thereby providing conceptual support for the validity of the study. A larger nested case-control study will be conducted to validate our findings.

Clinical Cellular Therapeutics Accelerate Clot Formation

Clinical cellular therapeutics (CCTs) have shown preliminary efficacy in reducing inflammation after trauma, preserving cardiac function after myocardial infarction, and improving functional recovery after stroke. However, most clinically available cell lines express tissue factor (TF) which stimulates coagulation. We sought to define the degree of procoagulant activity of CCTs as related to TF expression. CCT samples from bone marrow, adipose, amniotic fluid, umbilical cord, multi-potent adult progenitor cell donors, and bone marrow mononuclear cells were tested. TF expression and phenotype were quantified using flow cytometry. Procoagulant activity of the CCTs was measured in vitro with thromboelastography and calibrated thrombogram. Fluorescence-activated cell sorting (FACS) separated samples into high- and low-TF expressing populations to isolate the contribution of TF to coagulation. A TF neutralizing antibody was incubated with samples to demonstrate loss of procoagulant function. All CCTs tested expressed procoagulant activity that correlated with expression of tissue factor. Time to clot and thrombin formation decreased with increasing TF expression. High-TF expressing cells decreased clotting time more than low-TF expressing cells when isolated from a single donor using FACS. A TF neutralizing antibody restored clotting time to control values in some, but not all, CCT samples. CCTs demonstrate wide variability in procoagulant activity related to TF expression. Time to clot and thrombin formation decreases as TF load increases and this procoagulant effect is neutralized by a TF blocking antibody. Clinical trials using CCTs are in progress and TF expression may emerge as a safety release criterion. Stem Cells Translational Medicine 2018;7:731-739.