Challenging Traditional Paradigms in Posttraumatic Pulmonary Thromboembolism

Traumatic brain injury: Advances in coagulopathy (Review)

Trauma is a prevalent cause of coagulopathy, with traumatic brain injury (TBI) accompanied by coagulation disorders particularly linked to adverse outcomes. TBI is distinguished by minimal bleeding volume and unique injury sites, which precipitate complex coagulation disturbances. Historically, research into trauma-induced coagulopathy has primarily concentrated on the molecular biology and pathophysiology of endogenous anticoagulation and inflammation. Nonetheless, recognizing that cells are the fundamental units of structure and function in all living organisms, the present review aimed to distill our understanding of coagulopathy post-TBI by elucidating the intricate cellular mechanisms involving endothelial cells, neutrophils and platelets. Additionally, this study evaluates the strengths and weaknesses of various diagnostic tools and discusses the characteristics of pharmacological treatments and potential therapies for patients with TBI and coagulation disorders. The aim of this review is to amalgamate recent updates in mechanistic research and innovative diagnostic and therapeutic methodologies, thereby fostering the progression of precision medicine within this specialized domain.

Acute Pulmonary Embolism: Evidence, Innovation, and Horizons

PURPOSE OF REVIEW

Pulmonary embolism (PE) is the third most common cause of cardiovascular morbidity and mortality. The goal of this review is to discuss the most up-to-date literature on epidemiology, diagnosis, risk stratification, and management of acute PE.

RECENT FINDINGS

Despite an increase in annual incidence rate of PE in the United States and development of multiple advanced therapies for treatment of acute PE, PE-related mortality is not consistently decreasing across populations. Although multiple risk stratification schemes have been developed, it is still unclear which advanced therapy should be used for the individual patient and optimal timing. Fortunately, multiple randomized clinical trials are underway to answer these questions. Nevertheless, up to 50% of patients have persistent reduced quality of life 6 months after acute PE, termed post-PE syndrome. Despite advances in therapeutic options for management of acute PE, many questions remain unanswered, including optimal risk stratification and management of acute PE.

Venous thromboembolic events associated with blood product administration in an era of whole blood use

BACKGROUND

The risks associated with blood product administration and venous thromboembolic events remains unclear. We sought to determine which blood products were associated with the development of deep vein thrombosis (DVT) and pulmonary embolism (PE).

METHODS

We analyzed data from patients ≥18 years of age in the Trauma Quality Improvement Program (TQIP) database that received ≥1 blood product and survived ≥24 ​h.

RESULTS

There were 42,399 that met inclusion, of whom, 2086 had at least one VTE event. In our multivariable logistic regression model, we found that WB had a unit odds ratio (uOR) of 1.05 (95 ​% CI 1.02-1.08) for DVT and 1.08 (1.05-1.12) for PE. Compared to WB, platelets had a higher uOR for DVT of 1.09 (1.04-1.13) but similar uOR for PE of 1.08 (1.03-1.14).

CONCLUSIONS

We found an association of both DVT and PE with early whole blood and platelets.

A 20-year retrospective analysis of deep venous thrombosis and pulmonary embolism among combat casualties requiring damage-control laparotomy at US military Role 2 surgical units

BACKGROUND

Combat casualties receiving damage-control laparotomy at forward deployed, resource-constrained US military Role 2 (R2) surgical units require multiple evacuations, but the added risk of venous thromboembolism (VTE) in this population has not been defined. To fill this gap, we retrospectively analyzed 20 years of Department of Defense Trauma Registry data to define the VTE rate in this population.

METHODS

Department of Defense Trauma Registry from 2002 to 2023 was queried for US military combat casualties requiring damage-control laparotomy at R2. All deaths were excluded in subsequent analysis. Rates of VTE were assessed, and subgroup analysis was performed on patients requiring massive transfusion.

RESULTS

Department of Defense Trauma Registry (n = 288) patients were young (mean age, 25 years) and predominantly male (98%) with severe (mean Injury Severity Score, 26), mostly penetrating injury (76%) and high mortality. Venous thromboembolism rate was high: 15.8% (DVT, 10.3%; pulmonary embolism, 7.1%). In the massively transfused population, the VTE rate was even higher (26.7% vs. 10.2%, p < 0.001).

CONCLUSION

This is the first report that combat casualties requiring damage-control laparotomy at R2 have such high VTE rates. Therefore, for military casualties, we propose screening ultrasound upon arrival to each subsequent capable echelon of care and low threshold for initiating thromboprophylaxis.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Does preperitoneal packing increase venous thromboembolim risk among trauma patients? A prospective multicenter analysis across 17 level I trauma centers

INTRODUCTION

Pelvic fractures are associated with a high risk of venous thromboembolism (VTE). Among treatment options, including pelvic angioembolization (PA), preperitoneal pelvic packing (PPP), and pelvic open reduction internal fixation (ORIF), PPP has been postulated as a VTE risk factor. We aimed to characterize the risk of VTE among pelvic fracture patients receiving PPP, PA or ORIF.

METHODS

We used observational data from a 17-site Consortium of Leaders in the Study of Traumatic Thromboembolism (CLOTT) study group, a US level I trauma center collaborative working to identify factors associated with posttraumatic VTE, deep venous thrombosis, pulmonary embolism, or pulmonary thrombosis. The CLOTT criteria included age 18 to 40 years with at least one independent VTE risk factor. We compared outcomes of PPP, PA, and pelvic ORIF to reference of no pelvic intervention. Our primary outcome was VTE. A competing risk analysis was performed.

RESULTS

Among 1,387 pelvic fracture patients, VTE incidence was 5.6%. The ORIF patients were most likely to develop VTE (24.7%), while VTE incidence for PPP was 9.0% and 2.6% for PA. After multivariate, risk-competing analysis, none of the three treatment interventions for pelvic fractures were significantly associated with VTE. Initiation of VTE prophylaxis in the first 24 hours of admission independently halved VTE incidence (hazard ratio, 0.55; confidence interval, 0.33-0.91).

CONCLUSION

Pelvic fracture interventions do not appear to be independent risk factors for VTE in our study. Initiation of VTE pharmacoprophylaxis within the first 24 hours of admission remains critical to significantly decreasing VTE formation in this high-risk population.

LEVEL OF EVIDENCE

Therapeutic Study; Level III.

Protein profile of circulating extracellular vesicles reveals biomarker candidates for diagnosis of post-traumatic deep vein thrombosis

BACKGROUND AND OBJECTIVE

Deep vein thrombosis (DVT) is a common complication after trauma and mostly without specific symptoms. Timely diagnosis and early appropriate treatment measures can prevent further development of thrombosis for patients with traumatic lower extremity fractures. Although extracellular vesicles (EVs) are confirmed as promising disease biomarkers, little is known about the role of altered levels and composition in the diagnosis of post-traumatic DVT.

METHOD

The levels of circulating EVs subgroups were measured using flow cytometry. Isolated EVs were characterized and subjected to proteomics analysis to screen for differentially expressed proteins (DEPs) between DVT and non-DVT patients. Regularized logistic regression analysis based on L2 penalty terms using R's caret package was applied to build a model for DVT diagnosis.

RESULTS

Compared to non-DVT patients, DVT patients had higher circulating hepatocyte-derived EVs (hEVs) with good predictive value for post-traumatic DVT diagnosis. The results of the proteomic analysis showed that differentially expressed proteins (DEPs) of circulating EVs between the DVT group and non-DVT group were enriched in the complement and coagulation cascade. Finally, an integrated model of five biomarkers including SERPING1, C8G, CFH, FIX, and hEVs level was established for post-traumatic DVT diagnosis with robust identification of the traumatic patients with and without DVT (AUC 0.972).

CONCLUSION

Post-traumatic DVT patients had changed levels and composition of circulating EVs compared to non-DVT patients and healthy controls. Circulating EVs may acquire pathological protein signatures and become potential biomarkers for identifying subjects' post-traumatic DVT.

Traumatic lower extremity amputation as a risk factor for venous thromboembolism

BACKGROUND

This study aimed to evaluate whether lower extremity (LE) amputation among civilian casualties is a risk factor for venous thromboembolism.

METHODS

All patients with severe LE injuries (AIS ≥3) derived from the ACS-TQIP (2013-2020) were divided into those who underwent trauma-associated amputation and those with limb salvage. Propensity score matching was used to mitigate selection bias and confounding and compare the rates of pulmonary embolism (PE) and deep vein thrombosis (DVT).

RESULTS

A total of 145,667 patients with severe LE injuries were included, with 3443 patients requiring LE amputation. After successful matching, patients sustaining LE amputation still experienced significantly higher rates of PE (4.2% vs. 2.5%, p ​< ​0.001) and DVT (6.5% vs. 3.4%, p ​< ​0.001). A sensitivity analysis examining patients with isolated major LE trauma similarly showed a higher rate of thromboembolic complications, including higher incidences of PE (3.2% vs. 2.0%, p ​= ​0.015) and DVT (4.7% vs. 2.6%, p ​< ​0.001).

CONCLUSIONS

In this nationwide analysis, traumatic lower extremity amputation is associated with a significantly higher risk of VTE events, including PE and DVT.

'Door-to-prophylaxis' as a novel quality improvement metric in prevention of venous thromboembolism following traumatic injury

Objective

Venous thromboembolism (VTE) risk reduction strategies include early initiation of chemoprophylaxis, reducing missed doses, weight-based dosing and dose adjustment using anti-Xa levels. We hypothesized that time to initiation of chemoprophylaxis would be the strongest modifiable risk for VTE, even after adjusting for competing risk factors.

Methods

A prospectively maintained trauma registry was queried for patients admitted July 2017-October 2021 who were 18 years and older and received emergency release blood products. Patients with deep vein thrombosis or pulmonary embolism (VTE) were compared to those without (no VTE). Door-to-prophylaxis was defined as time from hospital arrival to first dose of VTE chemoprophylaxis (hours). Univariate and multivariate analyses were then performed between the two groups.

Results

2047 patients met inclusion (106 VTE, 1941 no VTE). There were no differences in baseline or demographic data. VTE patients had higher injury severity score (29 vs 24), more evidence of shock by arrival lactate (4.6 vs 3.9) and received more post-ED transfusions (8 vs 2 units); all p<0.05. While there was no difference in need for enoxaparin dose adjustment or missed doses, door-to-prophylaxis time was longer in the VTE group (35 vs 25 hours; p=0.009). On multivariate logistic regression analysis, every hour delay from time of arrival increased likelihood of VTE by 1.5% (OR 1.015, 95% CI 1.004 to 1.023, p=0.004).

Conclusion

The current retrospective study of severely injured patients with trauma who required emergency release blood products found that increased door-to-prophylaxis time was significantly associated with an increased likelihood for VTE. Chemoprophylaxis initiation is one of the few modifiable risk factors available to combat VTE, therefore early initiation is paramount. Similar to door-to-balloon time in treating myocardial infarction and door-to-tPA time in stroke, "door-to-prophylaxis time" should be considered as a hospital metric for prevention of VTE in trauma.

Level of evidence

Level III, retrospective study with up to two negative criteria.

Fibrinolysis Resistance After Injury Is a Risk Factor for a Hospital-Acquired Pneumonia-Like Disease Pattern

Background: Pneumonia is associated with increased morbidity and costs in the intensive care unit (ICU). Its early identification is key for optimal outcomes, but early biomarkers are lacking. Studies suggest that fibrinolysis resistance (FR) after major abdominal surgery is linked to an increased risk of infection. Patients and Methods: Patients in a randomized controlled trial for hemorrhagic shock were evaluated for FR. Fibrinolysis resistance was quantified by thrombelastography with exogenous tissue plasminogen activator (tPA-TEG) at 24- and 48-hours post-injury and measuring LY30 (%). A receiver-operating characteristics (ROC) curve analysis was used to identify a cutoff for increased risk of pneumonia, which was then validated in ICU patients at risk for venous thromboembolism (VTE). Multivariable logistic regression was used to control for confounders. Results: Forty-nine patients in the hemorrhagic shock cohort had tPA-TEGs at 24- and 48-hours (median ISS, 27; 7% pneumonia). A composite tPA-TEG LY30 of less than 4% at 24 and 48 hours was found to be the optimal cutoff for increased risk of pneumonia. This cohort had a seven-fold increased rate of pneumonia (4% vs. 28%; p = 0.048). Eighty-eight patients in the VTE cohort had tPA-TEGs at 24 and 48 hours post-ICU admission (median ISS, 28; 6% pneumonia). The tPA-TEG LY30 of less than 4% was associated with a 10-fold increased rate of pneumonia (19% vs. 1.5%; p = 0.002). In patients with traumatic brain injury, the same association was found (33% vs. 3.2%; p = 0.006). Adjusting for confounders, the tPA-TEG persisted as a substantial risk factor for pneumonia (adjusted odds ratio [OR], 35.7; 95% confidence interval [CI], 1.9-682; p = 0.018). Conclusions: Fibrinolysis resistance quantified by tPA-TEG within 48 hours of ICU admission is associated with an increased risk of pneumonia in patients in hemorrhagic shock and those at risk for VTE. Prospective validation of the tPA-TEG LY30 optimal cutoff for pneumonia and further investigation into whether endogenous FR is a cause of an altered immunity is warranted.

Platelets in Hemostasis, Thrombosis, and Inflammation After Major Trauma

Trauma currently accounts for 10% of the total global burden of disease and over 5 million deaths per year, making it a leading cause of morbidity and mortality worldwide. Although recent advances in early resuscitation have improved early survival from critical injury, the mortality rate in patients with major hemorrhage approaches 50% even in mature trauma systems. A major determinant of clinical outcomes from a major injury is a complex, dynamic hemostatic landscape. Critically injured patients frequently present to the emergency department with an acute traumatic coagulopathy that increases mortality from bleeding, yet, within 48 to 72 hours after injury will switch from a hypocoagulable to a hypercoagulable state with increased risk of venous thromboembolism and multiple organ dysfunction. This review will focus on the role of platelets in these processes. As effectors of hemostasis and thrombosis, they are central to each phase of recovery from injury, and our understanding of postinjury platelet biology has dramatically advanced over the past decade. This review describes our current knowledge of the changes in platelet behavior that occur following major trauma, the mechanisms by which these changes develop, and the implications for clinical outcomes. Importantly, supported by research in other disease settings, this review also reflects the emerging role of thromboinflammation in trauma including cross talk between platelets, innate immune cells, and coagulation. We also address the unresolved questions and significant knowledge gaps that remain, and finally highlight areas that with the further study will help deliver further improvements in trauma care.

Weight-based enoxaparin thromboprophylaxis in young trauma patients: analysis of the CLOTT-1 registry

Introduction

Optimal venous thromboembolism (VTE) enoxaparin prophylaxis dosing remains elusive. Weight-based (WB) dosing safely increases anti-factor Xa levels without the need for routine monitoring but it is unclear if it leads to lower VTE risk. We hypothesized that WB dosing would decrease VTE risk compared with standard fixed dosing (SFD).

Methods

Patients from the prospective, observational CLOTT-1 registry receiving prophylactic enoxaparin (n=5539) were categorized as WB (0.45-0.55 mg/kg two times per day) or SFD (30 mg two times per day, 40 mg once a day). Multivariate logistic regression was used to generate a predicted probability of VTE for WB and SFD patients.

Results

Of 4360 patients analyzed, 1065 (24.4%) were WB and 3295 (75.6%) were SFD. WB patients were younger, female, more severely injured, and underwent major operation or major venous repair at a higher rate than individuals in the SFD group. Obesity was more common among the SFD group. Unadjusted VTE rates were comparable (WB 3.1% vs. SFD 3.9%; p=0.221). Early prophylaxis was associated with lower VTE rate (1.4% vs. 5.0%; p=0.001) and deep vein thrombosis (0.9% vs. 4.4%; p<0.001), but not pulmonary embolism (0.7% vs. 1.4%; p=0.259). After adjustment, VTE incidence did not differ by dosing strategy (adjusted OR (aOR) 0.75, 95% CI 0.38 to 1.48); however, early administration was associated with a significant reduction in VTE (aOR 0.47, 95% CI 0.30 to 0.74).

Conclusion

In young trauma patients, WB prophylaxis is not associated with reduced VTE rate when compared with SFD. The timing of the initiation of chemoprophylaxis may be more important than the dosing strategy. Further studies need to evaluate these findings across a wider age and comorbidity spectrum.

Level of evidence

Level IV, therapeutic/care management.

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.

Combination of aspirin and rosuvastatin for reduction of venous thromboembolism in severely injured patients: a double-blind, placebo-controlled, pragmatic randomized phase II clinical trial (The STAT Trial)

INTRODUCTION

Venous thromboembolism (VTE) remains a significant source of postinjury morbidity and mortality. Beta-hydroxy beta-methylglutaryl-CoA (HMG-CoA) reductase inhibitors (rosuvastatin) significantly reduced pathologic clotting events in healthy populations in a prior trial. Furthermore, acetylsalicylic acid (ASA) has been shown to be noninferior to prophylactic heparinoids for VTE prevention following orthopedic surgery. We hypothesized that a combination of rosuvastatin/ASA, in addition to standard VTE chemoprophylaxis, would reduce VTE in critically ill trauma patients.

METHODS

This was a double-blind, placebo-controlled, randomized trial, evaluating VTE rates in two groups: ASA + statin (Experimental) and identical placebos (Control). Injured adults, 18-65 years old, admitted to the surgical intensive care unit without contraindications for VTE prophylaxis were eligible. Upon initiation of routine VTE chemoprophylaxis (i.e. heparin/heparin-derivatives), they were randomized to the Experimental or Control group. VTE was the primary outcome.

RESULTS

Of 112 potentially eligible patients, 33% (n = 37, median new injury severity scale = 27) were successfully randomized, of whom 11% had VTEs. The Experimental group had no VTEs, while the Control group had 6 VTEs (4 PEs and 2 DVTs) in 4 (22%) patients (P = 0.046). The Experimental treatment was not associated with any serious adverse events. Due to the COVID-19 pandemic, the study was interrupted at the second interim analysis at <10% of the planned enrollment, with significance declared at P < 0.012 at that stage.

DISCUSSION

The combination of ASA and rosuvastatin with standard VTE prophylaxis showed a favorable trend toward reducing VTEs with no serious adverse events. An appropriately powered phase III multicenter trial is needed to further investigate this therapeutic approach.

LEVEL OF EVIDENCE

Level II, Therapeutic.

Addition of aspirin to venous thromboembolism chemoprophylaxis safely decreases venous thromboembolism rates in trauma patients

Background

Trauma patients exhibit a multifactorial hypercoagulable state and have increased risk of venous thromboembolism (VTE). Despite early and aggressive chemoprophylaxis (CP) with various heparin compounds ("standard" CP; sCP), VTE rates remain high. In high-quality studies, aspirin has been shown to decrease VTE in postoperative elective surgical and orthopedic trauma patients. We hypothesized that inhibiting platelet function with aspirin as an adjunct to sCP would reduce the risk of VTE in trauma patients.

Methods

We performed a retrospective observational study of prospectively collected data from all adult patients admitted to an American College of Surgeons Level I Trauma center from January 2012 to June 2015 to evaluate the addition of aspirin (sCP+A) to sCP regimens for VTE mitigation. Cox proportional hazard models were used to assess the potential benefit of adjunctive aspirin for symptomatic VTE incidence.

Results

10,532 patients, median age 44 (IQR 28 to 62), 68% male, 89% blunt mechanism of injury, with a median Injury Severity Score (ISS) of 12 (IQR 9 to 19), were included in the study. 8646 (82%) of patients received only sCP, whereas 1886 (18%) patients received sCP+A. The sCP+A cohort displayed a higher median ISS compared with sCP (13 vs 11; p<0.01). The overall median time of sCP initiation was hospital day 1 (IQR 0.8 to 2) and the median day for aspirin initiation was hospital day 3 (IQR 1 to 6) for the sCP+A cohort. 353 patients (3.4%) developed symptomatic VTE. Aspirin administration was independently associated with a decreased relative hazard of VTE (HR 0.57; 95% CI 0.36 to 0.88; p=0.01). There were no increased bleeding or wound complications associated with sCP+A (point estimate 1.23, 95% CI 0.68 to 2.2, p=0.50).

Conclusion

In this large trauma cohort, adjunctive aspirin was independently associated with a significant reduction in VTE and may represent a potential strategy to safely mitigate VTE risk in trauma patients. Further prospective studies evaluating the addition of aspirin to heparinoid-based VTE chemoprophylaxis regimens should be sought.

Level of evidence

Level III/therapeutic.

The silent killer: Previously undetected pulmonary emboli that result in death after discharge

INTRODUCTION

Pulmonary embolism (PE) is a recognized cause of death in hospitalized trauma patients, yet less is known about PE after discharge.

PATIENTS & METHODS

All post-discharge, autopsy-demonstrated, fatal PE resulting from trauma within a large US county over six years were analyzed. Counts, percentages, mean values, SD, and IQR were calculated for all variables.

RESULTS

1848 trauma deaths were reviewed, of which 85% had an autopsy. Eighty-five patients died from PE after discharge from their initial injury. 53% were initially treated at non-trauma centers, and 9% did not seek medical assistance. 75% were injured by falling, and most injuries occurred in the lower extremities. 86% had an ISS <16, but 87% needed assistance or were bed-bound after injury, despite 75% having no mobility limitations before the injury. 53% died within one month of injury, and 91% within the first year. Before death, only 11% were prescribed chemical thromboprophylaxis or an antiplatelet agent, and only 8% were diagnosed with venous thromboembolism before death.

CONCLUSIONS

Fatal PE after discharge typically occurred following activity-limiting lower extremity injuries with an ISS<16.

Research priorities in venous thromboembolism after trauma: Secondary analysis of the National Trauma Research Action Plan

BACKGROUND

Venous thromboembolism (VTE) is a significant cause of morbidity and mortality during recovery from injury and can result in significant health care costs. Despite advances in the past several decades in our approach to VTE prophylaxis after injury, opportunities exist to improve the delivery and implementation of optimal VTE prophylaxis. Here, we aim to identify consensus research questions related to VTE across all National Trauma Research Action Plan (NTRAP) Delphi expert panels to further guide the research agenda aimed at preventing VTE after injury.

METHODS

This is a secondary analysis of consensus-based research priorities that were collected using a Delphi methodology by 11 unique NTRAP panels that were charged with unique topic areas across the spectrum of injury care. The database of questions was queried for the keywords "VTE," "venous thromboembo," and "DVT" and then grouped into relevant topic areas.

RESULTS

There were 86 VTE-related research questions identified across 9 NTRAP panels. Eighty-five questions reached consensus with 24 rated high priority; 60, medium priority; and 1, low priority. Questions related to the timing of VTE prophylaxis (n = 17) were most common, followed by questions related to risk factors for the development of VTE (n = 16), the effects of tranexamic acid on VTE (n = 11), the approach to dosing of pharmacologic prophylaxis (n = 8), and the pharmacologic prophylactic medication choice for optimal VTE prophylaxis (n = 6).

CONCLUSION

National Trauma Research Action Plan panelists identified 85 consensus-based research questions that should drive dedicated extramural research funding opportunities to support quality studies aimed at optimizing VTE prophylaxis after injury.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Does tranexamic acid increase venous thromboembolism risk among trauma patients? A prospective multicenter analysis across 17 level I trauma centers

IMPORTANCE

The early use of tranexamic acid (TXA) has demonstrated benefit among some trauma patients in hemorrhagic shock. The association between TXA administration and thromboembolic events (including deep vein thrombosis (DVT), pulmonary embolism (PE) and pulmonary thrombosis (PT)) remains unclear. We aimed to characterize the risk of venous thromboembolism (VTE) subtypes among trauma patients receiving TXA and to determine whether TXA is associated with VTE risk and mortality.

METHODS

We analyzed a prospective, observational, multicenter cohort data from the Consortium of Leaders in the Study of Traumatic Thromboembolism (CLOTT) study group. The study was conducted across 17 US level I trauma centers between January 1, 2018, and December 31,2020. We studied trauma patients ages 18-40 years, admitted for at least 48 h with a minimum of 1 VTE risk factor and followed until hospital discharge or 30 days. We compared TXA recipients to non-recipients for VTE and mortality using inverse probability weighted Cox models. The primary outcome was the presence of documented venous thromboembolism (VTE). The secondary outcome was mortality. VTE was defined as DVT, PE, or PT.

RESULTS

Among the 7,331 trauma patients analyzed, 466 (6.4%) received TXA. Patients in the TXA group were more severely injured than patients in the non-TXA group (ISS 16+: 69.1% vs. 48.5%, p < 0.001) and a higher percentage underwent a major surgical procedure (85.8% vs. 73.6%, p < 0.001). Among TXA recipients, 12.5% developed VTE (1.3% PT, 2.4% PE, 8.8% DVT) with 5.6% mortality. In the non-TXA group, 4.6% developed VTE (1.1% PT, 0.5% PE, 3.0% DVT) with 1.7% mortality. In analyses adjusting for patient demographic and clinical characteristics, TXA administration was not significantly associated with VTE (aHR 1.00, 95%CI: 0.69-1.46, p = 0.99) but was significantly associated with increased mortality (aHR 2.01, 95%CI: 1.46-2.77, p < 0.001).

CONCLUSION

TXA was not clearly identified as an independent risk factor for VTE in adjusted analyses, but the risk of VTE among trauma patients receiving TXA remains high (12.5%). This supports the judicious use of TXA in resuscitation, with consideration of early initiation of DVT prophylaxis in this high-risk group.

Venous thromboembolic disease in admitted blunt trauma patients: what matters?

BACKGROUND

Venous thromboembolic events (VTE) are a significant cause of morbidity and mortality following traumatic injury. We examined demographic characteristics, chemoprophylaxis, and outcomes of VTE patients with blunt trauma requiring hospitalization.

METHODS

A retrospective review of adult blunt trauma hospitalizations with and without VTE between 2012 and 2019 was conducted. Deaths in the emergency department were excluded. Univariate and multivariable analyses, including machine learning classification algorithms for VTE, were performed.

RESULTS

Of 10,926 admitted adult blunt trauma patients, 177 had VTE events. VTE events occurred at a median of 6 [IQR 3-11] days, with 7.3% occurring within 1 day of admission. VTE patients were more often male, and more often underwent surgery. They had higher injury severity as well as longer intensive care unit and hospital lengths of stay. While VTE occurred throughout the spectrum of injury severity, 27.7% had low injury severity (ISS < = 9). In multivariable analyses, both heparin and enoxaparin had reduced adjusted odds ratios for VTE.

CONCLUSION

Approximately 7.3% of VTE events occurred within one day of admission. A substantial proportion of VTE events occurred in patients with low injury severity (ISS < = 9). Subcutaneous unfractionated heparin and enoxaparin chemoprophylaxis were both inversely associated with VTE. These findings underscore the need for vigilance for VTE identification in blunt trauma patients throughout their hospitalization and VTE prevention efforts.

Low-molecular-weight heparin is superior to unfractionated heparin in lowering the risk of venous thromboembolism after traumatic lower extremity amputation

BACKGROUND

Patients undergoing lower extremity amputation after trauma are at high risk of venous thromboembolism. Practice variations persist regarding the optimal pharmacologic agent for venous thromboembolism prophylaxis in this patient population. We aimed to compare the efficacy of unfractionated heparin versus low-molecular-weight heparin in preventing venous thromboembolism.

METHODS

Using the 2013 to 2019 American College of Surgeons Pediatric Trauma Quality Improvement Program database, all trauma patients (≥18) who underwent lower limb amputation and received venous thromboembolism thromboprophylaxis in the form of unfractionated heparin or low-molecular-weight heparin were included. We excluded patients who died within 24 hours of admission or those who received no thromboprophylaxis. The primary outcome was the rate of venous thromboembolism. Multivariable logistic regression was used to evaluate the independent relationship between the type of pharmacologic prophylaxis and the risk of venous thromboembolism.

RESULTS

A total of 4,103 patients who underwent lower extremity amputation were identified. Patients were primarily young (median age 43 years) with blunt injuries (83%). The overall rate of venous thromboembolism was 8.6%. Most (77%) patients received low-molecular-weight heparin-based prophylaxis. Compared with patients without venous thromboembolism, the venous thromboembolism cohort had a greater injury severity score (19 vs 13, P < .001), had more patients undergoing above-the-knee amputation (48% vs 36%, P < .001), and less frequently received low-molecular-weight heparin (64% vs 78%, P < .001). Multivariable analysis showed that low-molecular-weight heparin was associated with a significantly lower venous thromboembolism rate than unfractionated heparin (odds ratio: 0.65 [0.51-0.83], P < .001).

CONCLUSION

Thromboprophylaxis with low-molecular-weight heparin was found to be superior to unfractionated heparin in lowering the risk of venous thromboembolism among traumatic amputees and should be the preferred pharmacologic agent in this patient population prone to venous thromboembolism.

Outcomes of Protocol-Driven Venous Thromboembolic Chemo-Prophylaxis in Trauma Patients: A Trauma Quality Improvement Project Analysis

INTRODUCTION

Low molecular weight heparin (LMWH) is the standard for venous thromboembolic (VTE) chemo-prophylaxis in trauma patients; however, inconsistencies in the use of LMWH exist. The objective of this study was to assess VTE outcomes in response to a chemo-prophylaxis protocol guided by patient physiology (eg, creatinine clearance) and comorbidities.

METHODS

ACS TQIP Benchmark Reports at a level 1 trauma center using a patient physiology and comorbidity directed VTE chemo-prophylaxis protocol were analyzed for Spring 2019 to Fall 2021. Patient demographics, VTE rates and pharmacologic VTE prophylaxis type were collected for "All Patients" and "Elderly" (TQIP: age ≥ 55 years) cohorts.

RESULTS

Data was analyzed for 1919183 "All Hospitals" (AH) and 5843 patients single institution (SI) using the physiologic and comorbidity guided VTE chemo-prophylaxis protocol. Elderly subgroup had 701965 (AH) and 2939 (SI) patients. Use of non-LMWH chemo-prophylaxis was significantly higher at SI: All patients = 62.6% SI vs 22.1% (P < .01); Elderly = 68.8% SI vs 28.1% AH (P < .01). VTE, DVT, and PE rates for All Patients and Elderly subgroup were significantly reduced at SI, except Elderly PE which was statistically equivalent.

CONCLUSIONS

Protocol-driven VTE chemo-prophylaxis was associated with significantly lower LMWH use accompanied by significant reductions in All VTE, DVT, PE, and Elderly VTE and DVT with no difference in Elderly PE rates. These results may imply that adherence to a physiologic and comorbidity directed chemo-prophylaxis protocol, rather than LMWH, reduces VTE events in trauma patients. Further investigation to elucidate best practice is warranted.

A Systematic Review of Tranexamic Acid-Associated Venous Thromboembolic Events in Combat Casualties and Considerations for Prolonged Field Care

INTRODUCTION

Tranexamic acid (TXA) is a standard component of Tactical Combat Casualty Care. Recent retrospective studies have shown that TXA use is associated with a higher rate of venous thromboembolic (VTE) events in combat-injured patients. We aim to determine if selective administration should be considered in the prolonged field care environment.

MATERIALS AND METHODS

We performed a systematic review using the 2020 Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Clinical trials and observational studies of combat casualties published between January 1, 1960, and June 20, 2022, were included. We analyzed survival and VTE outcomes in TXA recipients and non-recipients. We discussed the findings of each paper in the context of current and future combat environments.

RESULTS

Six articles met criteria for inclusion. Only one study was powered to report mortality data, and it demonstrated a 7-fold increase in survival in severely injured TXA recipients. All studies reported an increased risk of VTE in TXA recipients, which exceeded rates in civilian literature. However, five of the six studies used overlapping data from the same registry and were limited by a high rate of missingness in pertinent variables. No VTE-related deaths were identified.

CONCLUSIONS

There may be an increased risk of VTE in combat casualties that receive TXA; however, this risk must be considered in the context of improved survival and an absence of VTE-associated deaths. To optimize combat casualty care during prolonged field care, it will be essential to ensure the timely administration of VTE chemoprophylaxis as soon as the risk of significant hemorrhage permits.

Pulmonary embolism following severe polytrauma: a retrospective study from a level I trauma center in China

BACKGROUND

Trauma patients are at high risk of Venous thromboembolism (VTE), but compared to well-established deep venous thrombosis (DVT), data specifically evaluating post-traumatic pulmonary embolism (PE) are scarce. The aim of this study is to assess whether PE represents a distinct clinical entity with injury pattern, risk factors, and prophylaxis strategy different from DVT, among severe poly-trauma patients.

PATIENTS AND METHODS

We retrospectively enrolled patients admitted to our level I trauma center from January 2011 to December 2021 who were diagnosed with severe multiple traumatic injuries and identified thromboembolic events among them. We regarded four groups as None (without thromboembolic events), DVT only, PE only, and PE with DVT. Demographics, injury characteristics, clinical outcomes, and treatments were collected and analyzed in individual groups. Patients were also classified according to the occurring time of PE, and indicative symptoms and radiological findings were compared between early PE (≤ 3 days) and late PE (> 3 days). Logistic regression analyses were conducted to explore independent risk factors for different VTE patterns.

RESULTS

Among 3498 selected severe multiple traumatic patients, there were 398 episodes of DVT only, 19 of PE only, and 63 of PE with DVT. Injury variables associated with PE only included shock on admission and severe chest trauma. Severe pelvic fracture and mechanical ventilator days (MVD) ≥ 3 were the independent risk factors for PE with DVT. There were no significant differences in the indicative symptoms and location of pulmonary thrombi between the early and late PE groups. Obesity and severe lower extremity injury might have an impact on the incidence of early PE, while patients with a severe head injury and higher ISS are particularly at risk for developing late PE.

CONCLUSION

Occurring early, lacking association with DVT, and possessing distinct risk factors warrant PE in severe poly-trauma patients special attention, especially for its prophylaxis strategy.

In Situ Pulmonary Arterial Thrombosis-Literature Review and Clinical Significance of a Distinct Entity

Filling defects identified in the pulmonary arterial tree are commonly presumed to represent an embolic phenomenon originating from thrombi formed in remote veins, particularly lower-extremity deep venous thrombosis (DVT). However, accumulating evidence supports an underappreciated cause for pulmonary arterial thrombosis (PAT), namely, de novo thrombogenesis-where thrombosis arises within the pulmonary arteries in the absence of DVT. Although historically underrecognized, in situ PAT has become of heightened importance with the emergence of SARS-CoV-2 infection. In situ PAT is attributed to endothelial dysfunction, systemic inflammation, and acute lung injury, and has been described in a range of conditions including COVID-19, trauma, acute chest syndrome in sickle cell disease, pulmonary infections, and severe pulmonary arterial hypertension. The distinction between pulmonary embolus and in situ PAT may have important implications regarding management decisions and clinical outcomes. In this review, we summarize the pathophysiology, imaging appearances, and management of in situ PAT in various clinical situations. This understanding will promote optimal tailored treatment strategies for this increasingly recognized entity.

Hepatocyte-derived Microparticles as Novel Biomarkers for the Diagnosis of Deep Venous Thrombosis in Trauma Patients

Venous thromboembolism is a common complication following trauma. We investigated the dynamics of plasma microparticles (MPs) levels and explored their potential as biomarkers of deep vein thromboembolism (DVT) after trauma. A total of 775 patients with traumatic fractures were recruited in this nested study. About 106 trauma patients (53 DVT subjects and 53 age-, sex-, and fracture site-matched non-DVT subjects) and 53 healthy volunteers met the enrollment criteria. MPs were characterized by transmission electron microscope, nanoparticle tracking analysis, and western blotting. Circulating levels of MPs were measured using a flow cytometer. Meanwhile, routine laboratory parameters were examined in all patients. Compared to non-DVT patients, DVT patients had higher circulating phosphatidylserine (PS) + MPs, hepatocyte-derived MPs (HMPs), PS + HMPs, and platelet-derived MPs (PMPs). Notably, PS + HMPs had the best predictive value for DVT diagnosis in trauma patients (area under the curve [AUC] 0.8939, 95% CI 0.8326 to 0.9552), which was superior to d-dimer (AUC 0.5881). The Hepatic Procoagulant Index combined plasma levels of PS + HMPs and albumin, increasing the AUC to 0.8978 (95% CI 0.8396 to 0.9561). This is the first study that addressed circulating PS + HMPs are promising biomarkers with high performance in diagnosing DVT. The Hepatic Procoagulant Index is a potential predictor of DVT in trauma patients.

One size does not fit all: Sex bias in pharmacologic venous thromboembolism prophylaxis

BACKGROUND

The optimal enoxaparin dosing strategy to achieve venous thromboembolism (VTE) prophylaxis in trauma patients remains unclear. Current dosing guidelines often include weight, age, and renal function but still fail to achieve appropriate prophylactic anti-Xa levels in many patients. We hypothesized that additional patient factors influence anti-Xa response to enoxaparin in trauma patients.

METHODS

This is a retrospective review of patients admitted to a Level 1 trauma center for ≥4 days from July 2015 to September 2020, who received enoxaparin VTE prophylaxis per protocol (50-59 kg, 30 mg/dose; 60-99 kg, 40 mg/dose; ≥100 kg, 50 mg/dose; all doses every 12 hours) and had an appropriately timed peak anti-Xa level. Multivariate regression was performed to identify independent predictors of prophylactic anti-Xa levels (0.2-0.4 IU/mL) upon first measurement.

RESULTS

The cohort (N = 1,435) was 76.4% male, with a mean ± SD age of 49.9 ± 20.0 years and a mean ± SD weight of 82.5 ± 20.2 kg (males, 85.2 kg; females, 73.7 kg; p <0.001). Overall, 68.6% of patients (n = 984) had a prophylactic anti-Xa level on first assessment (69.6% of males, 65.1% of females). Males were more likely to have a subprophylactic level than females (22.1% vs. 8.0%, p <0.001), whereas females were more likely to have supraprophylactic levels than males (26.9% vs. 8.3%, p < 0.001). When controlling for creatinine clearance, anti-Xa level was independently associated with dose-to-weight ratio (odds ratio, 0.191 for 0.5 mg/kg; p < 0.001; confidence interval, 0.151-0.230) and female sex (odds ratio, 0.060; p < 0.001; confidence interval, 0.047-0.072). Weight and age were not significant when controlling for the other factors.

CONCLUSION

Male patients have a decreased anti-Xa response to enoxaparin when compared with female patients, leading to a greater incidence of subprophylactic anti-Xa levels in male patients at all dose-to-weight ratios. To improve the accuracy of VTE chemoprophylaxis, sex should be considered as a variable in enoxaparin dosing models.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

Venous thromboembolism risk after spinal cord injury: A secondary analysis of the CLOTT study

INTRODUCTION

Patients with spinal cord injury (SCI) are at high risk of venous thromboembolism (VTE). Pharmacologic VTE prophylaxis (VTEppx) is frequently delayed in patients with SCI because of concerns for bleeding risk. Here, we hypothesized that delaying VTEppx until >48 hours would be associated with increased risk of thrombotic events.

METHODS

This is a secondary analysis of the 2018 to 2020 prospective, observational, cohort Consortium of Leaders in the Study of Traumatic Thromboembolism (CLOTT) study of patients aged 18 to 40 years, at 17 US level 1 trauma centers. Patients admitted for >48 hours with documented SCI were evaluated. Timing of initiation of VTEppx, rates of thrombotic events (deep vein thrombosis [DVT] and pulmonary embolism [PE]), and missed VTEppx doses were analyzed. The primary outcome was VTE (DVT + PE).

RESULTS

There were 343 patients with SCI. The mean ± SD age was 29.0 ± 6.6 years, 77.3% were male, and 78.7% sustained blunt mechanism. Thrombotic events occurred in 33 patients (9.6%): 30 DVTs (8.7%) and 3 PEs (0.9%). Venous thromboembolism prophylaxis started at ≤24 hours in 21.3% of patients and 49.3% at ≤48 hours. The rate of VTE for patients started on VTEppx ≤48 hours was 7.1% versus 12.1% if started after 48 hours ( p = 0.119). After adjusting for differences in risk factors between cohorts, starting ≤48 hours was independently associated with fewer VTEs (odds ratio, 0.45; 95% confidence interval, 0.101-0.978; p = 0.044). Unfractionated heparin was associated with a VTE rate of 21.0% versus 7.5% in those receiving enoxaparin as prophylaxis ( p = 0.003). Missed doses of VTEppx were common (29.7%) and associated with increased thrombotic events, although this was not significant on multivariate analysis.

CONCLUSION

Rates of thrombotic events in patients with SCI are high. Prompt initiation of VTEppx with enoxaparin and efforts aimed at avoiding missed doses are critical to limit thrombotic events in these high-risk patients.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Effectiveness of a Patient Education Bundle on Venous Thromboembolism Prophylaxis Administration by Sex

INTRODUCTION

Venous thromboembolism (VTE) is a frequent cause of preventable harm among hospitalized patients. Many prescribed prophylaxis doses are not administered despite supporting evidence. We previously demonstrated a patient-centered education bundle improved VTE prophylaxis administration broadly; however, patient-specific factors driving nonadministration are unclear. We examine the effects of the education bundle on missed doses of VTE prophylaxis by sex.

METHODS

We performed a post-hoc analysis of a nonrandomized controlled trial to evaluate the differences in missed doses by sex. Pre-intervention and intervention periods for patients admitted to 16 surgical and medical floors between 10/2014-03/2015 (pre-intervention) and 04/2015-12/2015 (intervention) were compared. We examined the conditional odds of (1) overall missed doses, (2) missed doses due to patient refusal, and (3) missed doses for other reasons.

RESULTS

Overall, 16,865 patients were included (pre-intervention 6853, intervention 10,012), with 2350 male and 2460 female patients (intervention), and 6373 male and 5682 female patients (control). Any missed dose significantly reduced on the intervention floors among male (odds ratio OR 0.55; 95% confidence interval CI, 0.44-0.70, P < 0.001) and female (OR 0.59; 95% CI, 0.47-0.73, P < 0.001) patients. Similar significant reductions ensued for missed doses due to patient refusal (P < 0.001). Overall, there were no sex-specific differences (P-interaction >0.05).

CONCLUSIONS

Our intervention increased VTE prophylaxis administration for both female and male patients, driven by decreased patient refusal. Patient education should be applicable to a wide range of patient demographics representative of the target group. To improve future interventions, quality improvement efforts should be evaluated based on patient demographics and drivers of differences in care.

Preperitoneal Pelvic Packing is Associated With Increased Risk of Venous Thromboembolism

INTRODUCTION

Preperitoneal pelvic packing (PPP) is an important intervention for control of severe pelvic hemorrhage in blunt trauma patients. We hypothesized that PPP is associated with an increased incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE).

METHODS

A retrospective cohort analysis of blunt trauma patients with severe pelvic fractures (AIS ≥4) using the 2015-2017 American College of Surgeons-Trauma Quality Improvement Program database was performed. Patients who underwent PPP within four hours of admission were matched to patients who did not using propensity score matching. Matching was performed based on demographics, comorbidities, injury- and resuscitation-related parameters, vital signs at presentation, and initiation and type of prophylactic anticoagulation. The rates of DVT and PE were compared between the matched groups.

RESULTS

Out of 5129 patients with severe pelvic fractures, 157 (3.1%) underwent PPP within four h of presentation and were matched with 157 who did not. No significant differences were detected between the two matched groups in any of the examined baseline variables. Similarly, mortality and end-organ failure rates were not different. However, PPP patients were significantly more likely to develop DVT (12.7% versus 5.1%, P = 0.028) and PE (5.7% versus 0.0%, P = 0.003).

CONCLUSIONS

PPP in severe pelvic fractures secondary to blunt trauma is associated with an increased risk of DVT and PE. A high index of suspicion and a low threshold for screening for these conditions should be maintained in patients who undergo PPP.

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.