Thompson, Riley J.

Introduction: Calibrated automated thrombogram assay parameters have been shown to assess hypercoagulation state and, therefore, may independently predict posttrauma, symptomatic venous thromboembolism (VTE). Yet, calibrated automated thrombogram lacks high throughput and standardization, limiting diagnostic potential. This study analyzed thrombin generation (TG) profiles in trauma patients using a high-throughput assay, processing up to 10 samples at once, providing batch testing capabilities. We hypothesized that trauma patients who developed VTE would show distinct TG profiles compared with those who did not. Methods: Trauma patients presenting to a Level I Trauma Center had samples collected within 12 hours postinjury prospectively. Follow-up was conducted to 90 days, time to symptomatic VTE diagnosis or death, confirmed via autopsy or imaging. TG profiles were measured from the ST Genesia assay. Data were presented as median (interquartile ranges) or n (%), with the Wilcoxon rank-sum or chi-squared test. Associations between TG parameters and clinical risk factors were assessed using Spearman correlation analysis or the Wilcoxon rank-sum test. Results: Two hundred and fifty-four trauma patients were analyzed [48.5 years (31.0, 62.0), 72.0% male]: 64 patients with VTE (25.2%) to 190 with non-VTE. VTE pts had a median time to VTE of 8 days, with 29 developing deep venous thrombosis, 24 with pulmonary embolism, and 11 with deep venous thrombosis/pulmonary embolism. No significant differences were found in age, sex, or body mass index; significantly more VTE patients underwent surgery and blood transfusions within 24 hours. TG profiles demonstrated accelerated TG in patients who developed VTE compared with non-VTE, with significant differences in peak height ( P = 0.001), time to peak ( P = 0.021), endogenous thrombin potential ( P < 0.001), and velocity index ( P = 0.001). Conclusion: TG profiles using ST Genesia can differentiate trauma patients at high risk of developing VTE. The platform suits clinical labs needing high throughput by providing batch testing capabilities. Study type: Prospective study with less than large effect and no negative criteria. Level of evidence: II.

Objective: The identification of reliable biomarkers in trauma patients (pts) remains a clinical challenge. Nucleosomes, which are DNA wrapped around histone protein cores, have been used as reliable markers for quantification in sepsis, acute respiratory distress syndrome, and lymphoma. We hypothesized that: 1) levels of circulating nucleosomes quantified after traumatic injury, specifically histone H3.1 and its citrullinated R8 posttranslation modification (H3R8 Cit), would be increased after trauma and 2) that levels of circulating nucleosomes would be further, increased in pts who went on to develop venous thromboembolism (VTE), as these nucleosomes may be clot-enhancing mediators. Methods: Trauma pts presenting to a Level I trauma center were evaluated for inclusion in a prospective case-cohort study, and citrated blood samples were collected within 12 hours of injury. Pts were followed for up to 90 days and VTE occurrence was confirmed via autopsy or imaging. Pts who developed incident, symptomatic VTE, and those who did not develop VTE were selected at a 1:3 ratio. The effect of trauma was assessed by comparison with healthy volunteer samples. Circulating nucleosomes were quantified using Nu.Q H3.1 and Nu.Q H3R8 Cit assays. Data are presented as median [interquartile range] or n (%), with Wilcoxon Rank-Sum or chi-squared test performed between trauma pts who developed symptomatic VTE versus those who did not, with a P value < 0.05 as statistically significant. Results: A total of 639 trauma pts were analyzed [51 years (33, 65), 71.0% male, 94.1% blunt, injury severity scores 17 (9, 27)]. Both H3.1 [359.7 (58.4, 1769.3) vs. 21.5 (15.3, 26.6) ng/mL, P < 0.001] and H3R8 Cit levels [209.4 (45.4, 665.5) vs. 22.3 (16.2, 28.9) ng/mL, P < 0.001] were greater in trauma pts than in 10 healthy volunteers. The 160 pts with VTE were then compared with 479 without VTE. VTE pts had a median time to VTE of 8.5 days, with 91 developing symptomatic deep venous thrombosis, 48 with pulmonary embolism, and 21 with both deep venous thrombosis and pulmonary embolism. No significant differences were found in age, sex, or mechanism between pts with or without VTE. However, VTE pts had higher injury severity scores [24 (14, 34), 14 (9, 24), P < 0.001] and body mass index [29.1 (24.3, 34.2), 27.6 (24.2, 32.0) kg/m 2 , P = 0.037]. A greater percentage of VTE pts underwent surgery requiring general anesthesia (53.1%, 34.0%, P < 0.001) and received blood transfusions within 24 hours of injury (51.9%, 24.0%, P < 0.001). H3.1 levels were significantly greater in trauma pts who developed VTE compared with those who did not [828.4 (112.0, 3186.5), vs. 276.7 (50.3, 1237.0) ng/mL, P < 0.001], as were H3R8 Cit levels [350.4 (77.4, 729.5), vs. 189.2 (40.8, 632.6) ng/mL, P = 0.005]. No differences in levels of H3.1 and H3R8 Cit were found between early (diagnosed day 0–7 after injury) and late (diagnosed > day 7) VTE. Conclusions: Levels of the H3.1 and H3R8 Cit nucleosomes are elevated early after traumatic injury, especially in those who developed VTE. These findings underscore the importance of understanding the pathophysiology of nucleosomes in inducing VTE and their role as biomarkers

ABSTRACT Background: Neutrophil extracellular traps (NETs), and its formation and release, known as NETosis, may play a role in the initiation of thrombin generation (TG) in trauma. The objective of this study was to assess whether trauma patients, who develop symptomatic venous thromboembolism (VTE), have increased levels of plasma citrullinated histone H3 (CitH3) and accelerated TG kinetics. Methods: Patients presenting to a level I trauma center as trauma activations had samples collected within 12 h of time of injury, alongside healthy volunteers (HV). CitH3 was measured by enzyme-linked immunosorbent assay, and TG data were measured using a TG analyzer, comparing results between patients developing symptomatic VTE versus those who did not, within 90 days of injury. Data were expressed as median and quartiles (Q1, Q3), and tested using Wilcoxon rank-sum or Fisher’s exact test, or 1-sample test of Spearman’s correlation, P < 0.05 considered significant. Results: 39 trauma patient samples were analyzed (10 with and 29 without VTE), and compared to 15 HV samples. CitH3 levels in patients who developed VTE were significantly greater as compared to those who did not (12.8 ng/mL [7.1, 30.8]; 3.0 ng/mL [1.8,6.8], P = 0.024), with levels in both groups greater compared to HV (1.2 [0.3, 4.1], P = 0.003, P = 0.012), respectively. TG profiles were accelerated in patients developing VTE, with differences in peak height (337.6 nM [304.4, 356.0]; 231.8 nM [180.2, 281.8], P = 0.008), endogenous thrombin potential (1718.5 nM*min [1,500, 1794]; 1208.5 nM*min [1,072, 1,417], P = 0.003) and velocity index (213.2 nM/min [162.3, 260.5]; 124.3 nM/min [93.2, 223.1], P = 0.03), respectively. Conclusion: Trauma patients developing VTE exhibit increased NETosis, measured by increased CitH3 levels and accelerated TG early after injury, outlining an area for further understanding VTE after trauma.

Trauma-induced coagulopathy (TIC) is common after injury and reliable quantification of its severity is lacking. The objective of this study was to evaluate whether thrombin generation would be significantly altered if whole blood samples from trauma patients were collected without (citrate-only) and with corn trypsin inhibitor (CTI+). In a prospective cohort study, 36 trauma pts presenting to a Level I Trauma Center within 12 hours of injury, had whole blood collected simultaneously in citrate-only (3.2%) and citrated plus CTI (CTI+ [final 25 ug/mL]), and processed to platelet free plasma by double centrifugation (3000g, 15 minutes). Samples were stored at -80C with no thawing until analysis. Thrombin generation profiles were measured using the ST Genesia assay (Diagnostica STAGO SAS) and parameters included endogenous thrombin potential (ETP), lag time (LT), peak height, start of tail, velocity index, and time to peak (ttPeak) were analyzed for trauma pts. Data presented as median [IQR] or n (%), with paired t-test and Spearman's correlation analysis were performed between citrated non-CTI and citrated CTI spiked blood samples, with p-value &lt;0.05 statistically significant. Pts presented with significant injury ISS 13 [5, 21], age 45 [29, 59] years, 80.6% male, BMI 26.9 [25.4, 28.3], 94.4% blunt trauma, 22.3% had surgery by day 1 of admission. Significant differences were found between the citrated-only and CTI +tubes in several thrombin generation parameters: ETP (1339 Nm*min [1172.5,1417], 1124.5 [925.4,1285], p&lt;0.001), peak height (222.3 Nm [186.0, 275.6], 160.6 [132.7,208.3], p&lt;0.001), ttPeak (5.64 min [4.86,6.63], 6.19 [5.36, 7.34], p&lt;0.001), start of tail (19.4 min [17.6,21.3], 21.6 [18.9, 23.6], p=0.014), and velocity index (117.6 Nm/min [77.9, 163.1], 71.9 [54.9,106.0], p&lt;0.001). However, LT (3.14 min [2.74, 3.90], 3.08 [2.84, 3.96], p=0.665) did not show a statistically significant difference. Spearman's correlation analysis showed high correlation between citrate-only and CTI+ citrated plasma samples, with Spearman's rank correlation coefficients for LT (0.941), peak height (0.760), ttPeak (0.928), ETP (0.770), start of tail (0.869), and velocity index (0.766) respectively. The results suggest that use of CTI+ decrease thrombin generation kinetics from blood samples obtained from trauma patients. These findings underscore the need for careful consideration of sample collection and processing for use of thrombin generation assays in clinical setting. However, there is very strong correlation of the thrombin parameters obtained from citrated-only plasma to CTI+ plasma samples, suggesting they capture similar information. CTI-spiked citrated tubes appear to reduce contact activation with respect to thrombin generation profiles compared to standard citrated only tubes. This should be a consideration for platform-based lab processing of thrombin generation assays for assessment of coagulopathy after injury; however, given the cost of CTI, citrated-only tubes can be an option for characterization of thrombin generation profile in clinical samples.

ABSTRACT 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.