Tranexamic acid is associated with increased mortality in patients with physiological fibrinolysis

Deranged Balance of Hemostasis and Fibrinolysis in Disseminated Intravascular Coagulation: Assessment and Relevance in Different Clinical Settings

The disruption of hemostasis/fibrinolysis balance leads to disseminated intravascular coagulation, manifested clinically by bleeding or thrombosis, and multiorgan failure. This study reviews hemostatic assessment and therapeutic strategies that restore this balance in critically ill patients.

Are Data Driving Our Ambulances? Liberal Use of Tranexamic Acid in the Prehospital Setting

BACKGROUND

Current data on tranexamic acid (TXA) supports early administration for severe hemorrhagic shock. Administration by EMS has been facilitated by developing protocols and standing orders informed by these data. In this study, patterns of TXA use by EMS agencies serving a large level 1 trauma center were examined. We hypothesized that current widespread TXA use often includes administration outside of data-driven indications.

METHODS

The trauma registry at a level 1 trauma center was queried for patients who received TXA. To determine the practice patterns and appropriateness of administration of TXA, patients' physiologic state in the prehospital environment based on EMS records, physiologic state on arrival to hospital, and interventions performed in both settings were examined. Over 20 separately managed EMS systems that administer TXA transport patients to this trauma center, allowing for a broad survey of practices.

RESULTS

From 2016 to 2021 1089 patients received TXA, 406 (37.3%) having treatment initiated by EMS services. Of these, the average prehospital systolic blood pressure (SBP) was 108.2 mmHg and initial ED SBP was 107.8 mmHg. Only 58.4% of these patients received blood transfusion after arrival to this trauma center. Compliance with standard indications was low with only 14.6% of administrations meeting any data-driven SBP indication. Similar levels of compliance were seen across high volume EMS services.

DISCUSSION

Tranexamic acid use has become common in trauma and has been adopted by many EMS systems. These results indicate TXA in the prehospital setting is over-used as administration is not being limited to indications that have shown benefit in prior data.

Association of fibrinolysis phenotype with patient outcomes following traumatic brain injury

BACKGROUND

Impaired coagulation is associated with elevated risk of mortality in trauma patients. Prior studies have demonstrated increased mortality in patients with hyperfibrinolysis (HF) and fibrinolysis shutdown (SD). In addition, prior studies have demonstrated no effect of tranexamic acid (TXA) on fibrinolysis phenotypes. We examined the association of admission fibrinolysis phenotype with traumatic brain injury (TBI) patient outcomes.

METHODS

Data were extracted from a placebo-controlled multicenter clinical trial. Patients ≥15 years with TBI (Glasgow Coma Scale score, 3-12) and systolic blood pressure ≥90 mm Hg were randomized in the out-of-hospital setting to receive placebo bolus/placebo infusion (Placebo), 1 gram (g) TXA bolus/1 g TXA infusion (bolus maintenance [BM]); or 2 g TXA bolus/placebo infusion (bolus only [BO]). Fibrinolysis phenotypes on admission were determined by clot lysis at 30 minutes (LY30): SD, ≤0.8%; physiologic, 0.9% to 2.9%; HF, ≥3%. Logistic regression was used to control for age, sex, penetrating injury, Injury Severity Score, maximum head AIS, and TXA treatment group.

RESULTS

Seven hundred forty-seven patients met inclusion criteria. Fibrinolysis shutdown was the most common phenotype in all treatment groups and was associated with increased age, Injury Severity Score, and presence of intracranial hemorrhage (ICH). Inpatient mortality was 15.2% for SD and HF, and 10.6% for physiologic ( p = 0.49). No differences in mortality, disability rating scale at 6 months, acute kidney injury, acute respiratory distress syndrome, or multi-organ failure were noted between fibrinolysis phenotypes.

CONCLUSION

SD is the most common phenotype expressed in moderate to severe TBI. In TBI, there is no association between fibrinolysis phenotype and mortality or other major complications.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Thromboembolic Complications Following Perioperative Tranexamic Acid Administration

INTRODUCTION

The antifibrinolytic tranexamic acid (TXA) may reduce death in trauma; however, outcomes associated with TXA use in patients without proven hyperfibrinolysis remain unclear. We analyzed the associations of empirically administered TXA, hypothesizing that TXA use would correlate to lower transfusion totals but increased thromboembolic complications.

METHODS

This retrospective cohort study compared trauma patients started on massive transfusion protocol at a Level I trauma center from 2016 to 2021 who either did or did not receive TXA. Our primary outcome was in-hospital mortality. Venous thromboembolism (VTE; pulmonary embolism or deep vein thrombosis), transfusion volumes, and coagulation measures were considered secondarily. Descriptive statistics, univariate analyses, and multivariable logistic regression were used to evaluate differences in outcomes.

RESULTS

TXA patients presented with lower systolic blood pressure (100 versus 119.5 mmHg, P = 0.009), trended toward higher injury severity (ISS of 25 versus 20, P = 0.057), and were likelier to have undergone thoracotomy or laparotomy (89 versus 71%, P = 0.002). After adjusting for age, mechanism, presenting vitals, and operation, TXA was not significantly associated with mortality or VTE. TXA patients had larger volumes of packed red blood cells, platelets, and plasma transfused within 4- and 24-h (P ≤ 0.002). No differences in clot stability, captured via thromboelastography, were noted.

CONCLUSIONS

Despite no differences in mortality or VTE between patients who did and did not receive TXA, there were significant differences in transfusion totals. TXA patients had worse presenting physiology and likely had more severe bleeding. This absence of adverse outcomes supports TXA's safety. Nevertheless, further inquiry into the precise mechanism of TXA may help guide its empiric use, allowing for more targeted application.

Mechanisms and management of the coagulopathy of trauma and sepsis: trauma-induced coagulopathy, sepsis-induced coagulopathy, and disseminated intravascular coagulation

Disseminated intravascular coagulation can occur due to different causes but commonly following sepsis. Trauma-induced coagulopathy (TIC) occurs on hospital arrival in approximately 25% of seriously injured patients who initially presents with impaired hemostasis and a bleeding phenotype that can later progress to a prothrombotic phase. Following traumatic injury, ineffective hemostasis is driven by massive blood loss, tissue damage, and hyperfibrinolysis. This initial impaired hemostasis continues until surgical or other management strategies not only to stop the causes of hemorrhage but also progresses to a prothrombotic and hypofibrinolytic state, also termed fibrinolytic shutdown. Prothrombotic progression is also promoted by inflammatory mediator release, endothelial injury, and platelet dysregulation, which is commonly seen in sepsis with increased mortality. Unlike TIC, the early phase of sepsis is frequently complicated by multiorgan dysfunction described as sepsis-induced coagulopathy (SIC) that lacks a hemorrhagic phase. The phenotypes of SIC and TIC are different, especially in their initial presentations; however, patients who survive TIC may also develop subsequent infections and potentially sepsis and SIC. Although the pathophysiology of SIC and TIC are different, endothelial injury, dysregulated fibrinolysis, and coagulation abnormalities are common. Management includes treatment of the underlying cause, tissue injury vs infection is critical, and supportive therapies, such as hemostatic resuscitation and circulatory support are essential, and adjunct therapies are recommended in guidelines. Based on clinical studies and certain guidelines, additional therapies include tranexamic acid in the limited timing of initial traumatic injury and anticoagulants, such as antithrombin and recombinant thrombomodulin in disseminated intravascular coagulation.

Sensitivity and specificity of thromboelastography for hyperfibrinolysis: Comparison of TEG 5000 and TEG 6S CK LY30 systems

OBJECTIVES

The sensitivity and specificity of clot lysis at 30 minutes after maximum clot strength (LY30), as measured by thromboelastography (TEG), for clinically significant hyperfibrinolysis have not been compared across the 2 US Food and Drug Administration-approved instruments (the TEG 5000 and TEG 6s [Haemonetics]).

METHODS

We performed a retrospective, single-center analysis of these 2 instruments using the kaolin (CK) reagent.

RESULTS

Local verification studies showed that the TEG 5000 and TEG 6s CK LY30 upper limits of normal (ULNs) were distinct (5.0% and 3.2%, respectively). Retrospective analysis of patient data showed that abnormal LY30 was 6 times more prevalent with the TEG 6s than with the TEG 5000 instrument. LY30 was a significant predictor of mortality with both instruments (TEG 6s: receiver operating characteristic [ROC] area under the curve [AUC] = 0.836, P ≤ .0001; TEG 5000: ROC AUC = 0.779, P = .028). The optimal LY30 cut point was determined based on these mortality data for each instrument. The TEG 6s showed superior mortality prediction than the TEG 5000 at lower LY30 levels (≥10%), with likelihood ratios of 8.22 and 2.62 for the TEG 6s and TEG 5000, respectively. Patients with a TEG 6s CK LY30 of 10% or higher were significantly more likely to die, receive cryoprecipitate, receive transfusions, or receive massive transfusion than patients with a TEG 6s LY30 of 3.3% to 9.9% (all P < .01). Patients with a TEG 5000 LY30 of 17.1% or higher were significantly more likely to die or use cryoprecipitate (P < .05); transfusion and massive transfusion protocol were not significantly different. Whole blood spiking studies showed that 70 ng/mL tissue plasminogen activator (tPA) achieved an average LY30 of approximately 10% for both instruments.

CONCLUSIONS

CK LY30 above the ULN is a sensitive but not specific cutoff for hyperfibrinolysis. At least moderately elevated CK LY30 carries more clinical portent on the TEG 6s instrument than on the TEG 5000. These TEG instruments are not sensitive to low concentrations of tPA.

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.

A new global fibrinolysis capacity assay for the sensitive detection of hyperfibrinolysis and hypofibrinogenemia in trauma patients

BACKGROUND

Conventional clotting tests are not expeditious enough to allow timely targeted interventions in trauma, and current point-of-care analyzers, such as rotational thromboelastometry (ROTEM), have limited sensitivity for hyperfibrinolysis and hypofibrinogenemia.

OBJECTIVES

To evaluate the performance of a recently developed global fibrinolysis capacity (GFC) assay in identifying fibrinolysis and hypofibrinogenemia in trauma patients.

METHODS

Exploratory analysis of a prospective cohort of adult trauma patients admitted to a single UK major trauma center and of commercially available healthy donor samples was performed. Lysis time (LT) was measured in plasma according to the GFC manufacturer's protocol, and a novel fibrinogen-related parameter (percentage reduction in GFC optical density from baseline at 1 minute) was derived from the GFC curve. Hyperfibrinolysis was defined as a tissue factor-activated ROTEM maximum lysis of >15% or LT of ≤30 minutes.

RESULTS

Compared to healthy donors (n = 19), non-tranexamic acid-treated trauma patients (n = 82) showed shortened LT, indicative of hyperfibrinolysis (29 minutes [16-35] vs 43 minutes [40-47]; p < .001). Of the 63 patients without overt ROTEM-hyperfibrinolysis, 31 (49%) had LT of ≤30 minutes, with 26% (8 of 31) of them requiring major transfusions. LT showed increased accuracy compared to maximum lysis in predicting 28-day mortality (area under the receiver operating characteristic curve, 0.96 [0.92-1.00] vs 0.65 [0.49-0.81]; p = .001). Percentage reduction in GFC optical density from baseline at 1 minute showed comparable specificity (76% vs 79%) to ROTEM clot amplitude at 5 minutes from tissue factor-activated ROTEM with cytochalasin D in detecting hypofibrinogenemia but correctly reclassified >50% of the patients with false negative results, leading to higher sensitivity (90% vs 77%).

CONCLUSION

Severe trauma patients are characterized by a hyperfibrinolytic profile upon admission to the emergency department. The GFC assay is more sensitive than ROTEM in capturing hyperfibrinolysis and hypofibrinogenemia but requires further development and automation.

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.

[The chapters "Stop the bleed-prehospital" and "Coagulation management and volume therapy (emergency departement)" in the new S3 guideline "Polytrauma/severe injury treatment"]

The S3 guideline on the treatment of patients with severe/multiple injuries by the German Association of the Scientific Medical Societies was updated between 2020 and 2022. This article describes the essence of the new chapter "Stop the bleed-prehospital" and the revised chapter "Coagulation management and volume therapy".

Beyond uterine atony: characterizing postpartum hemorrhage coagulopathy

BACKGROUND

Postpartum hemorrhage is a leading cause of morbidity and mortality worldwide, yet the associated early coagulopathy is not well defined.

OBJECTIVE

We hypothesized that women who develop postpartum hemorrhage have a distinct derangement of thrombin generation and coagulation factors compared with postpartum women without postpartum hemorrhage.

STUDY DESIGN

This prospective study of pregnant patients with postpartum hemorrhage was completed at a single urban hospital. Blood was drawn on postpartum hemorrhage diagnosis and 2 and 4 hours later. Assays of patients with postpartum hemorrhage included thrombelastography, whole blood thrombin generation, coagulation factor activity, tissue factor levels and activity, and tissue factor pathway inhibitor levels, which were compared with that of patients without postpartum hemorrhage.

RESULTS

A total of 81 patients were included in this study. Of those patients, 66 had postpartum hemorrhage, and 15 served as controls. Compared with patients without PPH, patients with postpartum hemorrhage had lower fibrinogen levels (469.0 mg/dL vs 411.0 mg/dL; P=.02), increased tissue plasminogen activator resistance (fibrinolysis 30 minutes after maximal clot strength: 8.7% vs 4.2%; P=.02), decreased peak thrombin concentration (150.2 nM vs 40.7 nM; P=.01), and decreased maximal rate of thrombin generation (60.1 nM/minute vs 2.8 nM/minute; P=.02). Furthermore, compared with patients without postpartum hemorrhage, patients with postpartum hemorrhage had decreased tissue factor levels (444.3 pg/mL vs 267.1 pg/mL; P=.02) and increased tissue factor pathway inhibitor levels (0.6 U/mL vs 0.8 U/mL; P=.04), with decreased tissue factor pathway inhibitor ratios (624 vs 299; P=.01).

CONCLUSION

PPH is not only an issue of uterine tone and mechanical bleeding but also a distinct coagulopathy that is characterized by decreased fibrinogen level, clot breakdown resistance, and markedly low thrombin generation. This pathology seemed to be driven by low tissue factor and high tissue factor pathway inhibitor levels.

Crosstalk between Inflammation and Hemorrhage/Coagulation Disorders in Primary Blast Lung Injury

Primary blast lung injury (PBLI), caused by exposure to high-intensity pressure waves from explosions in war, terrorist attacks, industrial production, and life explosions, is associated with pulmonary parenchymal tissue injury and severe ventilation insufficiency. PBLI patients, characterized by diffused intra-alveolar destruction, including hemorrhage and inflammation, might deteriorate into acute respiratory distress syndrome (ARDS) with high mortality. However, due to the absence of guidelines about PBLI, emergency doctors and rescue teams treating PBLI patients rely on experience. The goal of this review is to summarize the mechanisms of PBLI and their cross-linkages, exploring potential diagnostic and therapeutic targets of PBLI. We summarize the pathophysiological performance and pharmacotherapy principles of PBLI. In particular, we emphasize the crosstalk between hemorrhage and inflammation, as well as coagulation, and we propose early control of hemorrhage as the main treatment of PBLI. We also summarize several available therapy methods, including some novel internal hemostatic nanoparticles to prevent the vicious circle of inflammation and coagulation disorders. We hope that this review can provide information about the mechanisms, diagnosis, and treatment of PBLI for all interested investigators.

SHock-INduced Endotheliopathy (SHINE): A mechanistic justification for viscoelastography-guided resuscitation of traumatic and non-traumatic shock

Irrespective of the reason for hypoperfusion, hypocoagulable and/or hyperfibrinolytic hemostatic aberrancies afflict up to one-quarter of critically ill patients in shock. Intensivists and traumatologists have embraced the concept of SHock-INduced Endotheliopathy (SHINE) as a foundational derangement in progressive shock wherein sympatho-adrenal activation may cause systemic endothelial injury. The pro-thrombotic endothelium lends to micro-thrombosis, enacting a cycle of worsening perfusion and increasing catecholamines, endothelial injury, de-endothelialization, and multiple organ failure. The hypocoagulable/hyperfibrinolytic hemostatic phenotype is thought to be driven by endothelial release of anti-thrombogenic mediators to the bloodstream and perivascular sympathetic nerve release of tissue plasminogen activator directly into the microvasculature. In the shock state, this hemostatic phenotype may be a counterbalancing, yet maladaptive, attempt to restore blood flow against a systemically pro-thrombotic endothelium and increased blood viscosity. We therefore review endothelial physiology with emphasis on glycocalyx function, unique biomarkers, and coagulofibrinolytic mediators, setting the stage for understanding the pathophysiology and hemostatic phenotypes of SHINE in various etiologies of shock. We propose that the hyperfibrinolytic phenotype is exemplified in progressive shock whether related to trauma-induced coagulopathy, sepsis-induced coagulopathy, or post-cardiac arrest syndrome-associated coagulopathy. Regardless of the initial insult, SHINE appears to be a catecholamine-driven entity which early in the disease course may manifest as hyper- or hypocoagulopathic and hyper- or hypofibrinolytic hemostatic imbalance. Moreover, these hemostatic derangements may rapidly evolve along the thrombohemorrhagic spectrum depending on the etiology, timing, and methods of resuscitation. Given the intricate hemochemical makeup and changes during these shock states, macroscopic whole blood tests of coagulative kinetics and clot strength serve as clinically useful and simple means for hemostasis phenotyping. We suggest that viscoelastic hemostatic assays such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are currently the most applicable clinical tools for assaying global hemostatic function-including fibrinolysis-to enable dynamic resuscitation with blood products and hemostatic adjuncts for those patients with thrombotic and/or hemorrhagic complications in shock states.

The effect of tranexamic acid dosing regimen on trauma/hemorrhagic shock-related glycocalyx degradation and endothelial barrier permeability: An in vitro model

BACKGROUND

Improved outcomes with early tranexamic acid (TXA) following trauma hemorrhagic shock (T/HS) may be related to its antifibrinolytic, as well as anti-inflammatory properties. Previous in vitro studies have shown that early TXA administration protects against T/HS endothelial barrier dysfunction and associated glycocalyx degradation. An intact endothelial glycocalyx may protect against subsequent neutrophil mediated tissue injury. We postulated that early TXA administration would mitigate against glycocalyx damage and resultant neutrophil adherence and transmigration through the endothelial barrier. This was studied in vitro using a microfluidic flow platform.

METHODS

Human umbilical vein endothelial cell monolayers were subjected to control or shock conditions (hypoxia + epinephrine) followed by administration of TXA 90 minutes or 180 minutes later.

RESULTS

"Early" TXA administration protected against glycocalyx degradation, biomarkers of increased permeability and the development of a fibrinolytic phenotype. This was associated with decreased neutrophil endothelial adherence and transmigration. There were no differences in low versus high TXA concentrations. The protective effects were only significant with "early" TXA administration.

CONCLUSION

There was a concentration and temporal effect of TXA administration on endothelial glycocalyx degradation. This was associated with "vascular leakiness" as indexed by the relative ratio of Ang-2/1 and polymorphonuclear neutrophil transmigration. Tranexamic acid if administered in patients with T/HS should be administered "early"; this includes in the prehospital setting.

Precision Medicine: Clinical Tolerance to Hyperfibrinolysis Differs by Shock and Injury Severity

The definition of hyperfibrinolysis based on thrombelastogram LY30 measurements should vary with trauma patient characteristics, i.e., as anatomic injury or shock severity increase, the ability to tolerate even mild degrees of fibrinolysis is markedly reduced. This trend is independent of institutional practice patterns. The management of hyperfibrinolysis, particularly with anti-fibrinolytics administration, should be interpreted in the context of injury severity/shock and managed on an individual patient basis.

Association of Tranexamic Acid Administration With Mortality and Thromboembolic Events in Patients With Traumatic Injury: A Systematic Review and Meta-analysis

IMPORTANCE

Tranexamic acid is widely available and used off-label in patients with bleeding traumatic injury, although the literature does not consistently agree on its efficacy and safety.

OBJECTIVE

To examine the association of tranexamic acid administration with mortality and thromboembolic events compared with no treatment or with placebo in patients with traumatic injury in the literature.

DATA SOURCES

On March 23, 2021, PubMed, Embase, and the Cochrane Library were searched for eligible studies published between 1986 and 2021.

STUDY SELECTION

Randomized clinical trials and observational studies investigating tranexamic acid administration compared with no treatment or placebo among patients with traumatic injury and traumatic brain injury who were 15 years or older were included. Included studies were published in English or German. The electronic search yielded 1546 records, of which 71 were considered for full-text screening. The selection process was performed independently by 2 reviewers.

DATA EXTRACTION AND SYNTHESIS

The study followed the Cochrane Handbook for Systematic Reviews of Interventions and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data were extracted by 2 independent reviewers and pooled using the inverse-variance random-effects model.

MAIN OUTCOMES AND MEASURES

Outcomes were formulated before data collection and included mortality at 24 hours and 28 and 30 days (1 month) as well as the incidence of thromboembolic events and the amount of blood products administered. Owing to missing data, overall mortality was added and the amount of blood products administered was discarded.

RESULTS

Thirty-one studies with a total of 43 473 patients were included in the systematic review. The meta-analysis demonstrated that administration of tranexamic acid was associated with a significant decrease in 1-month mortality compared with the control cohort (risk ratio, 0.83 [95% CI, 0.71-0.97]; I2 = 35%). The results of meta-analyses for 24-hour and overall mortality and thromboembolic events were heterogeneous and could not be pooled. Further investigations on clinical heterogeneity showed that populations with trauma and trial conditions differed markedly.

CONCLUSIONS AND RELEVANCE

These findings suggest that tranexamic acid may be beneficial in various patient populations with trauma. However, reasonable concerns about potential thromboembolic events with tranexamic acid remain.

To Tranexamic Acid or Not to Tranexamic Acid? Accuracy of Antifibrinolytic Administration at Altitude

OBJECTIVE

Tranexamic acid (TXA) has demonstrated a reduction in all-cause mortality in trauma patients with hemorrhage. Administering TXA in the prehospital setting presents unique challenges because the identification of bleeding is based on clinical suspicion without advanced imaging or diagnostic tools. The objective of this study was to examine whether prehospital suspicion of bleeding is validated by in-hospital computed tomographic imaging and examination and to determine if patients received TXA in the absence of hemorrhage. The study was conducted at a level 1 trauma center supported by air medical transport services.

METHODS

This is a retrospective cohort study examining 88 trauma patients receiving prehospital TXA to treat suspected hemorrhage. Adult trauma patients who received TXA during the study period and were transported to our level 1 trauma center were included. A panel of trauma surgeons reviewed CT imaging and examination findings to retrospectively identify significant hemorrhage.

RESULTS

Forty-three percent of patients who received TXA during air medical transport did not have confirmed hemorrhage upon arrival.

CONCLUSION

TXA was given to a significant number of patients who did not have confirmed hemorrhage upon arrival. We recommend that institutions using TXA perform this internal validation to ensure they are accurately identifying hemorrhage in the prehospital setting.

Efficacy and safety of the second in-hospital dose of tranexamic acid after receiving the prehospital dose: double-blind randomized controlled clinical trial in a level 1 trauma center

Background

Prehospital administration of tranexamic acid (TXA) to injured patients is increasing worldwide. However, optimal TXA dose and need of a second infusion on hospital arrival remain undetermined. We investigated the efficacy and safety of the second in-hospital dose of TXA in injured patients receiving 1 g of TXA in the prehospital setting. We hypothesized that a second in-hospital dose of TXA improves survival of trauma patients.

Methods

A prospective, double-blind, placebo-controlled randomized, clinical trial included adult trauma patients receiving 1 g of TXA in the prehospital settings. Patients were then blindly randomized to Group I (second 1-g TXA) and Group II (placebo) on hospital arrival. The primary outcome was 24-h (early) and 28-day (late) mortality. Secondary outcomes were thromboembolic events, blood transfusions, hospital length of stay (HLOS) and organs failure (MOF).

Results

A total of 220 patients were enrolled, 110 in each group. The TXA and placebo groups had a similar early [OR 1.000 (0.062–16.192); p = 0.47] and late mortality [OR 0.476 (95% CI 0.157–1.442), p = 0.18].The cause of death (n = 15) was traumatic brain injury (TBI) in 12 patients and MOF in 3 patients. The need for blood transfusions in the first 24 h, number of transfused blood units, HLOS, thromboembolic events and multiorgan failure were comparable in the TXA and placebo groups. In seriously injured patients (injury severity score > 24), the MTP activation was higher in the placebo group (31.3% vs 11.10%, p = 0.13), whereas pulmonary embolism (6.9% vs 2.9%, p = 0.44) and late mortality (27.6% vs 14.3%, p = 0.17) were higher in the TXA group but did not reach statistical significance.

Conclusion

The second TXA dose did not change the mortality rate, need for blood transfusion, thromboembolic complications, organ failure and HLOS compared to a single prehospital dose and thus its routine administration should be revisited in larger and multicenter studies.

Trial registration

ClinicalTrials.gov Identifier: NCT03846973.

Temporal Transitions in Fibrinolysis after Trauma: Adverse Outcome Is Principally Related to Late Hypofibrinolysis

BACKGROUND

The relationship between late clinical outcomes after injury and early dynamic changes between fibrinolytic states is not fully understood. The authors hypothesized that temporal transitions in fibrinolysis states using rotational thromboelastometry (ROTEM) would aid stratification of adverse late clinical outcomes and improve understanding of how tranexamic acid modulates the fibrinolytic response and impacts mortality.

METHODS

The authors conducted a secondary analysis of previously collected data from trauma patients enrolled into an ongoing prospective cohort study (International Standard Randomised Controlled Trial Number [ISRCTN] 12962642) at a major trauma center in the United Kingdom. ROTEM was performed on admission and at 24 h with patients retrospectively grouped into three fibrinolysis categories: tissue factor-activated ROTEM maximum lysis of less than 5% (low); tissue factor-activated ROTEM maximum lysis of 5 to 15% (normal); or tissue factor-activated ROTEM maximum lysis of more than 15% (high). Primary outcomes were multiorgan dysfunction syndrome and 28-day mortality.

RESULTS

Seven-hundred thirty-one patients were included: 299 (41%) were treated with tranexamic acid and 432 (59%) were untreated. Two different cohorts with low-maximum lysis at 24 h were identified: (1) severe brain injury and (2) admission shock and hemorrhage. Multiple organ dysfunction syndrome was greatest in those with low-maximum lysis on admission and at 24 h, and late mortality was four times higher than in patients who remained normal during the first 24 h (7 of 42 [17%] vs. 9 of 223 [4%]; P = 0.029). Patients that transitioned to or remained in low-maximum lysis had increased odds of organ dysfunction (5.43 [95% CI, 1.43 to 20.61] and 4.85 [95% CI, 1.83 to 12.83], respectively). Tranexamic acid abolished ROTEM hyperfibrinolysis (high) on admission, increased the frequency of persistent low-maximum lysis (67 of 195 [34%]) vs. 8 of 79 [10%]; P = 0.002), and was associated with reduced early mortality (28 of 195 [14%] vs. 23 of 79 [29%]; P = 0.015). No increase in late deaths, regardless of fibrinolysis transition patterns, was observed.

CONCLUSIONS

Adverse late outcomes are more closely related to 24-h maximum lysis, irrespective of admission levels. Tranexamic acid alters early fibrinolysis transition patterns, but late mortality in patients with low-maximum lysis at 24 h is not increased.

EDITOR’S PERSPECTIVE

The Pathophysiology and Management of Hemorrhagic Shock in the Polytrauma Patient

The recognition and management of life-threatening hemorrhage in the polytrauma patient poses several challenges to prehospital rescue personnel and hospital providers. First, identification of acute blood loss and the magnitude of lost volume after torso injury may not be readily apparent in the field. Because of the expression of highly effective physiological mechanisms that compensate for a sudden decrease in circulatory volume, a polytrauma patient with a significant blood loss may appear normal during examination by first responders. Consequently, for every polytrauma victim with a significant mechanism of injury we assume substantial blood loss has occurred and life-threatening hemorrhage is progressing until we can prove the contrary. Second, a decision to begin damage control resuscitation (DCR), a costly, highly complex, and potentially dangerous intervention must often be reached with little time and without sufficient clinical information about the intended recipient. Whether to begin DCR in the prehospital phase remains controversial. Furthermore, DCR executed imperfectly has the potential to worsen serious derangements including acidosis, coagulopathy, and profound homeostatic imbalances that DCR is designed to correct. Additionally, transfusion of large amounts of homologous blood during DCR potentially disrupts immune and inflammatory systems, which may induce severe systemic autoinflammatory disease in the aftermath of DCR. Third, controversy remains over the composition of components that are transfused during DCR. For practical reasons, unmatched liquid plasma or freeze-dried plasma is transfused now more commonly than ABO-matched fresh frozen plasma. Low-titer type O whole blood may prove safer than red cell components, although maintaining an inventory of whole blood for possible massive transfusion during DCR creates significant challenges for blood banks. Lastly, as the primary principle of management of life-threatening hemorrhage is surgical or angiographic control of bleeding, DCR must not eclipse these definitive interventions.

Current Practices in Tranexamic Acid Administration for Pediatric Trauma Patients in the United States

BACKGROUND

Although controversial, early administration of tranexamic acid (TXA) has been shown to reduce mortality in adult patients with major trauma. Tranexamic acid has also been successfully used in elective pediatric surgery, with significant reduction in blood loss and transfusion requirements. There are limited data to guide its use in pediatric trauma patients. We sought to determine the current practices for TXA administration in pediatric trauma patients in the United States.

METHODS

A survey was conducted of all the American College of Surgeons-verified Level I and II trauma centers in the United States. The survey data underwent quantitative analysis.

RESULTS

Of the 363 Level I and II qualifying centers, we received responses from 220 for an overall response rate of 61%. Eighty of 99 verified pediatric trauma centers responded for a pediatric trauma center response rate of 81%. Of all responding centers, 148 (67%) reported they care for pediatric trauma patients, with an average of 513 pediatric trauma patients annually. The pediatric trauma centers report caring for an average of 650 pediatric trauma patients annually. Of all centers caring for pediatric trauma, 52 (35%) report using TXA, with the most common initial dosing being 15 mg/kg (68%). A follow-up infusion was utilized by 45 (87%) of the programs, most commonly dosed at 2 mg/kg/hr × 8 hr utilized by 24 centers (54%).

CONCLUSION

Although the clinical evidence for TXA in pediatric trauma patients is limited, we believe that consideration should be given for use in major trauma with hemodynamic instability or significant risk for ongoing hemorrhage. If available, resuscitation should be guided by thromboelastography to identify candidates who would most benefit from antithrombolytic administration. This represents a low-cost/low-risk and high-yield therapy for pediatric trauma patients.

Tranexamic acid for the prevention and treatment of bleeding in surgery, trauma and bleeding disorders: a narrative review

OBJECTIVES

We review the evidence for tranexamic acid (TXA) for the treatment and prevention of bleeding caused by surgery, trauma and bleeding disorders. We highlight therapeutic areas where evidence is lacking and discuss safety issues, particularly the concern regarding thrombotic complications.

METHODS

An electronic search was performed in PubMed and the Cochrane Library to identify clinical trials, safety reports and review articles.

FINDINGS

TXA reduces bleeding in patients with menorrhagia, and in patients undergoing caesarian section, myomectomy, hysterectomy, orthopedic surgery, cardiac surgery, orthognathic surgery, rhinoplasty, and prostate surgery. For dental extractions in patients with bleeding disorders or taking antithrombotic drugs, as well as in cases of idiopathic epistaxis, tonsillectomy, liver transplantation and resection, nephrolithotomy, skin cancer surgery, burn wounds and skin grafting, there is moderate evidence that TXA is effective for reducing bleeding. TXA was not effective in reducing bleeding in traumatic brain injury and upper and lower gastrointestinal bleeding. TXA reduces mortality in patients suffering from trauma and postpartum hemorrhage. For many of these indications, there is no consensus about the optimal TXA dose. With certain dosages and with certain indications TXA can cause harm, such as an increased risk of seizures after high TXA doses with brain injury and cardiac surgery, and an increased mortality after delayed administration of TXA for trauma events or postpartum hemorrhage. Whereas most trials did not signal an increased risk for thrombotic events, some trials reported an increased rate of thrombotic complications with the use of TXA for gastro-intestinal bleeding and trauma.

CONCLUSIONS

TXA has well-documented beneficial effects in many clinical indications. Identifying these indications and the optimal dose and timing to minimize risk of seizures or thromboembolic events is work in progress.

The impact of prehospital tranexamic acid on mortality and transfusion requirements: match-pair analysis from the nationwide German TraumaRegister DGU®

Background

Outcome data about the use of tranexamic acid (TXA) in civilian patients in mature trauma systems are scarce. The aim of this study was to determine how severely injured patients are affected by the widespread prehospital use of TXA in Germany.

Methods

The international TraumaRegister DGU® was retrospectively analyzed for severely injured patients with risk of bleeding (2015 until 2019) treated with at least one dose of TXA in the prehospital phase (TXA group). These were matched with patients who had not received prehospital TXA (control group), applying propensity score-based matching. Adult patients (≥ 16) admitted to a trauma center in Germany with an Injury Severity Score (ISS) ≥ 9 points were included.

Results

The matching yielded two comparable cohorts (n = 2275 in each group), and the mean ISS was 32.4 ± 14.7 in TXA group vs. 32.0 ± 14.5 in control group (p = 0.378). Around a third in both groups received one dose of TXA after hospital admission. TXA patients were significantly more transfused (p = 0.022), but needed significantly less packed red blood cells (p ≤ 0.001) and fresh frozen plasma (p = 0.023), when transfused. Massive transfusion rate was significantly lower in the TXA group (5.5% versus 7.2%, p = 0.015). Mortality was similar except for early mortality after 6 h (p = 0.004) and 12 h (p = 0.045). Among non-survivors hemorrhage as leading cause of death was less in the TXA group (3.0% vs. 4.3%, p = 0.021). Thromboembolic events were not significantly different between both groups (TXA 6.1%, control 4.9%, p = 0.080).

Conclusion

This is the largest civilian study in which the effect of prehospital TXA use in a mature trauma system has been examined. TXA use in severely injured patients was associated with a significantly lower risk of massive transfusion and lower mortality in the early in-hospital treatment period. Due to repetitive administration, a dose-dependent effect of TXA must be discussed.

Safety and efficacy of thromboelastography guidance of antifibrinolytic therapy in trauma patients: An observational cohort analysis

Background:

Tranexamic acid (TXA) is an antifibrinolytic therapy intended to decrease blood loss and improve hemostasis in traumatic hemorrhage. Viscoelastic assays, such as thromboelastography (TEG), allow for the identification of a patient's specific hemostasis. The purpose of this research study was to explore the safety and efficacy of TEG-guided antifibrinolytic therapy in trauma patients.

Methods:

This study was a retrospective review of trauma patients meeting institution-specific inclusion criteria for TXA. Patients were assigned to fibrinolytic groups per TEG LY30 data. Safety outcomes (24-h mortality, overall in-hospital mortality, and thromboembolic events) were compared between patients who did or did not receive TXA and within fibrinolytic groups. Mortality outcomes were adjusted for baseline Injury Severity Score (ISS). Secondary aims included blood product utilization, length of hospital, and intensive care unit stay.

Results:

Hypofibrinolysis was the most common fibrinolytic phenotype. Adjusting for ISS, there were no significant differences in mortality. A 30.7% thromboembolism incidence was identified in the TXA group compared to 16.6% not receiving TXA (P = 0.26), with 72.7% of these patients experiencing fibrinolytic shutdown.

Conclusions:

There were no differences in 24-h mortality, all-cause mortality, or secondary outcomes. The difference in thromboembolic rates between patients receiving TXA and those who did not, while not statistically significant, poses clinical concern.

Tranexamic acid is associated with reduced complement activation in trauma patients with hemorrhagic shock and hyperfibrinolysis on thromboelastography

: Trauma with hemorrhagic shock causes massive tissue plasminogen activator release, plasmin generation, and hyperfibrinolysis. Tranexamic acid (TXA) has recently been used to treat bleeding in trauma by preventing plasmin generation to limit fibrinolysis. Trauma patients also have increased complement activation that correlates with mortality and organ failure, but the source of activation is not clear, and plasmin has recently been shown to efficiently cleave C3 and C5 to their activated fragments. We hypothesized that trauma patients in hemorrhagic shock with hyperfibrinolysis on thromboelastography (TEG) LY30 would have increased complement activation at early time points, as measured by soluble C5b-9 complex, and TXA would prevent this. Plasma samples were obtained from an unrelated, previously performed IRB-approved prospective randomized study of trauma patients. Three groups were studied with n = 5 patients in each group: patients without hyperfibrinolysis (TEG LY30 < 3%) (who therefore did not get TXA), patients with hyperfibrinolysis (TEG LY30 > 3%) who did not get TXA, and patients with hyperfibrinolysis who were then treated with TXA. We found that patients who did not receive TXA, regardless of fibrinolytic phenotype, had elevated soluble C5b-9 levels at 6 h relative to emergency department levels. In contrast, all five patients with initial TEG LY30 more than 3% and were then treated with TXA had reduced soluble C5b-9 levels at 6 h relative to emergency department levels. There were no differences in PF1 + 2, Bb, or C4d levels between groups, suggesting that coagulation and complement activation pathways may not be primarily responsible for the observed differences.

Does Liberal Prehospital and In-Hospital Tranexamic Acid Influence Outcome in Severely Injured Patients? A Prospective Cohort Study

Background

Early hemorrhage control is important in trauma-related death prevention. Tranexamic acid (TXA) has shown to be beneficial in patients in hemorrhagic shock, although widespread adoption might result in incorrect TXA administration leading to increased morbidity and mortality.

Methods

A 7-year prospective cohort study with consecutive trauma patients admitted to a Level-1 Trauma Center ICU was performed to investigate administration of both pre- and in-hospital TXA and its relation to morbidity and mortality. Indication for prehospital and in-hospital TXA administration was (suspicion of) hemorrhagic shock, and/or systolic blood pressure (SBP) ≤ 90 mmHg. Demographics, data on physiology, resuscitation and outcomes were prospectively collected.

Results

Four hundred and twenty-two patients (71% males, median ISS 29, 95% blunt injuries) were included. Even though TXA patients were more severely injured with more deranged physiology, no differences in outcome were noted. Overall, thrombo-embolic complication rate was 8%. In half the patients, hemorrhagic shock was the indication for prehospital TXA, whereas 79% of in-hospital TXA was given based on suspicion of hemorrhagic shock. Thirteen percent of patients with SBP ≤ 90 mmHg in ED received no TXA at all. Based on SBP alone, 22% of prehospital TXA and 25% of in-hospital TXA were justified.

Conclusions

Despite being more severely injured, TXA patients had similar outcome compared to patients without TXA. Thrombo-embolic complication rate was low despite liberal use of both prehospital and in-hospital TXA. Caution should be exercised in selecting patients for TXA, although this might be challenging based on SBP alone in patients who do not yet show signs of deranged physiology on arrival in ED.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00268-021-06143-y.

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.

Fibrinolysis in Traumatic Brain Injury: Diagnosis, Management, and Clinical Considerations

Posttraumatic coagulopathy involves disruption of both the coagulation and fibrinolytic pathways secondary to tissue damage, hypotension, and inflammatory upregulation. This phenomenon contributes to delayed complications after traumatic brain injury (TBI), including intracranial hemorrhage progression and systemic disseminated intravascular coagulopathy. Development of an early hyperfibrinolytic state may result in uncontrolled bleeding and is associated with increased mortality in patients with TBI. Although fibrinolytic assays are not routinely performed in the assessment of posttraumatic coagulopathy, circulating biomarkers such as D-dimer and fibrin degradation products have demonstrated potential utility in outcome prediction. Unfortunately, the relatively delayed nature of these tests limits their clinical utility. In contrast, viscoelastic tests are able to provide a rapid global assessment of coagulopathy, although their ability to reliably identify disruptions in the fibrinolytic cascade remains unclear. Limited evidence supports the use of hypertonic saline, cryoprecipitate, and plasma to correct fibrinolytic disruption; however, some studies suggest more harm than benefit. Recently, early use of tranexamic acid in patients with TBI and confirmed hyperfibrinolysis has been proposed as a strategy to further improve clinical outcomes. Moving forward, further delineation of TBI phenotypes and the clinical implications of fibrinolysis based on phenotypic variation is needed. In this review, we summarize the clinical aspects of fibrinolysis in TBI, including diagnosis, treatment, and clinical correlates, with identification of targeted areas for future research efforts.

Glycocalyx components affect platelet function, whole blood coagulation, and fibrinolysis: an in vitro study suggesting a link to trauma-induced coagulopathy

BACKGROUND

The mechanisms of trauma induced coagulopathy (TIC) are considered multifactorial. Amongst others, however, shedding of the endothelial glycocalyx resulting in increased concentrations of glycocalyx fragments in plasma might also play a role. Thus, we hypothesized that shedded glycocalyx components affect coagulation and may act as humoral mediators of TIC.

METHODS

To investigate effects of heparan sulfate, chondroitin sulfate, syndecan-1, versican, and thrombomodulin we added these fragments to in vitro assays of whole blood from healthy volunteers to yield concentrations observed in trauma patients. Platelet function, whole blood coagulation, and fibrinolysis were measured by standard coagulation tests, impedance aggregometry (IA), and viscoelastic tests (VET). To assess dose-response relationships, we performed IA with increasing concentrations of versican and VET with increasing concentrations of thrombomodulin.

RESULTS

Intrinsically activated clotting times (i.e., activated partial thromboplastin time and intrinsically activated VET with and without heparinase) were unaffected by any glycocalyx fragment. Thrombomodulin, however, significantly and dose-dependently diminished fibrinolysis as assessed by VET with exogenously added rt-PA, and increased rt-PA-induced lysis Indices after 30 (up to 108% of control, p <  0,0001), 45 (up to 368% of control, p <  0,0001), and 60 min (up to 950% of control, p <  0,0001) in VET. Versican impaired platelet aggregation in response to arachidonic acid (up to - 37,6%, p <  0,0001), ADP (up to - 14,5%, p <  0,0001), and collagen (up to - 31,8%, p <  0,0001) in a dose-dependent manner, but did not affect TRAP-6 induced platelet aggregation. Clotting time in extrinsically activated VET was shortened by heparan sulfate (- 7,2%, p = 0,024), chondroitin sulfate (- 11,6%, p = 0,016), versican (- 13%, p = 0,012%), and when combined (- 7,2%, p = 0,007).

CONCLUSIONS

Glycocalyx components exert distinct inhibitory effects on platelet function, coagulation, and fibrinolysis. These data do not support a 'heparin-like auto-anticoagulation' by shed glycosaminoglycans but suggest a possible role of versican in trauma-induced thrombocytopathy and of thrombomodulin in trauma-associated impairment of endogenous fibrinolysis.

Plasmin thrombelastography rapidly identifies trauma patients at risk for massive transfusion, mortality, and hyperfibrinolysis: A diagnostic tool to resolve an international debate on tranexamic acid?

BACKGROUND

Trauma patients with hyperfibrinolysis and depletion of fibrinolytic inhibitors (DFIs) measured by thrombelastography (TEG) gain clot strength with TXA, but TEG results take nearly an hour. We aimed to develop an assay, plasmin TEG (P-TEG), to more expeditiously stratify risk for massive transfusion (MT), mortality, and hyperfibrinolysis.

METHODS

Trauma patients (N = 148) were assessed using TEG assays without exogenous additives (rapid/native), with exogenous plasmin (P-TEG) or tissue plasminogen activator (tPA TEG). The plasmin dose used does not effect healthy-control clot lysis 30 minutes after maximum amplitude (LY30) but causes shortened reaction time (R time) relative to native TEG (P-TEG R time < native TEG R time considered P-TEG negative). If P-TEG R time is greater than or equal to native TEG R time, the patient was considered P-TEG positive. Each assay's ability to predict MT, mortality, and (risk for) hyperfibrinolysis was determined. χ and Mann-Whitney U tests were used to compare categorical and continuous variables, respectively. Results were reported as median ± interquartile range or n (%).

RESULTS

Plasmin TEG provided results faster than all other assays (4.7 ± 2.5-9.1 minutes), approximately 11-fold faster than rapid-TEG (rTEG) LY30 (54.2 ± 51.1-58.1 minutes; p < 0.001). Plasmin TEG-positive patients had greater than fourfold higher MT rate (30% vs. 7%; p = 0.0015) with an area under the receiver operating characteristic curve of 0.686 (p = 0.028), greater than fourfold higher 24-hour mortality (33.3% vs. 7.8%; p = 0.0177), greater than twofold higher 30-day mortality (35% vs. 16.4%; p = 0.0483), higher rates of DFI (55% vs. 18%; p < 0.001), and a trend toward elevated D-dimer (19.9 vs. 3.3 μg/mL; p = 0.14). Plasmin TEG was associated with hyperfibrinolysis on rTEG LY30 at the 7.6% threshold (p = 0.04) but not the 3% threshold (p = 0.40). Plasmin TEG performed best in relation to DFI, with a positive predictive value of 58% and negative predictive value of 81%. When combined with tPA TEG time to maximum amplitude, P-TEG outperformed rTEG LY30 for predicting MT (area under the receiver operating characteristic curve, 0.811 vs. 0.708).

CONCLUSION

Within 5 minutes, P-TEG can stratify patients at highest risk for MT, mortality, and risk for hyperfibrinolysis. In composite with tPA TEG time to maximum amplitude, P-TEG outperforms rTEG LY30 for predicting MT and does so four times faster (12.7 vs. 54.1 minutes). The rapid results of P-TEG may be useful for those who practice selective TXA administration to maximize TXA's time-dependent efficacy.

LEVEL OF EVIDENCE

Diagnostic test, level V.

Do all cardiac surgery patients benefit from antifibrinolytic therapy?

BACKGROUND

In trauma patients, the recognition of fibrinolysis phenotypes has led to a re-evaluation of the risks and benefits of antifibrinolytic therapy (AF). Many cardiac patients also receive AF, but the distribution of fibrinolytic phenotypes in that population is unknown. The purpose of this hypothesis-generating study was to fill that gap.

METHODS

Seventy-eight cardiac surgery patients were retrospectively reviewed. Phenotypes were defined as hypofibrinolytic (LY30 <0.8%), physiologic (0.8%-3.0%), and hyperfibrinolytic (>3%) based on thromboelastogram.

RESULTS

The population was 65 ± 10-years old, 74% male, average body mass index of 29 ± 5 kg/m² . Fibrinolytic phenotypes were distributed as physiologic = 45% (35 of 78), hypo = 32% (25 of 78), and hyper = 23% (18 of 78). There was no obvious effect of age, gender, race, or ethnicity on this distribution; 47% received AF. For AF versus no AF, the time with chest tube was longer (4 [1] vs. 3 [1] days, p = .037), and all-cause morbidity was more prevalent (51% vs. 25%, p = .017). However, when these two groups were further stratified by phenotypes, there were within-group differences in the percentage of patients with congestive heart failure (p = .022), valve disease (p = .024), on-pump surgery (p < .0001), estimated blood loss during surgery (p = .015), transfusion requirement (p = .015), and chest tube output (p = .008), which highlight other factors along with AF that might have affected all-cause morbidity.

CONCLUSION

This is the first description of the prevalence of three different fibrinolytic phenotypes and their potential influence on cardiac surgery patients. The use of AF was associated with increased morbidity, but because of the small sample size and treatment allocation bias, additional confirmatory studies are necessary. We hope these present findings open the dialog on whether it is safe to administer AFs to cardiac surgery patients who are normo- or hypofibrinolytic.

A rat model of orthopedic injury-induced hypercoagulability and fibrinolytic shutdown

BACKGROUND

Postinjury hypercoagulability occurs in >25% of injured patients, increasing risk of thromboembolic complications despite chemoprophylaxis. However, few clinically relevant animal models of posttraumatic hypercoagulability exist. We aimed to evaluate a rodent model of bilateral hindlimb injury as a preclinical model of postinjury hypercoagulability.

METHODS

Forty Wistar rats were anesthetized with isoflurane: 20 underwent bilateral hindlimb fibula fracture, soft tissue and muscular crush injury, and bone homogenate injection intended to mimic the physiological severity of bilateral femur fracture. Twenty sham rats underwent anesthesia only. Terminal citrated blood samples were drawn at 0, 6, 12, and 24 hours (n = 5 per timed group) for analysis by native thromboelastography in the presence and absence of taurocholic acid to augment fibrinolysis. Plasminogen activator inhibitor 1 and α-2 antiplasmin levels in plasma were assessed via enzyme-linked immunosorbent assay.

RESULTS

Injured rats became hypercoagulable relative to baseline by 6 hours based on thromboelastography maximal amplitude (MA) and G (p < 0.005); sham rats became hypercoagulable to a lesser degree by 24 hours (p < 0.005). Compared with sham animals, injured rats were hypercoagulable by MA and G within 6 hours of injury, remained hypercoagulable by MA and G through at least 24 hours (all p < 0.01), and showed impaired fibrinolysis by taurocholic acid LY30 at 12 hours (p = 0.019) and native LY30 at 24 hours (p = 0.045). In terms of antifibrinolytic mediators, α-2 antiplasmin was elevated in trauma animals at 24 hours (p = 0.009), and plasminogen activator inhibitor 1 was elevated in trauma animals at 6 hours (p = 0.004) and 12 hours (p < 0.001) when compared with sham.

CONCLUSIONS

Orthopedic injury in rodents induced platelet and overall hypercoagulability within 6 hours and fibrinolytic impairment by 12 to 24 hours, mimicking postinjury hypercoagulability in injured patients. This rodent model of orthopedic injury may serve as a preclinical testing ground for potential therapies to mitigate hypercoagulability, maintain normal fibrinolysis, and prevent thromboembolic complications.

The incidence of venous thromboembolic events in trauma patients after tranexamic acid administration: an EAST multicenter study

To determine if there is a significant association between administration of tranexamic acid (TXA) in severely bleeding, injured patients, and venous thromboembolism (VTE), myocardial infarction (MI), or cerebrovascular accident (CVA). A multicenter, retrospective study was performed. Inclusion criteria were: age 18-80 years old and need for 5 units or more of blood in the first 24 h after injury. Exclusion criteria included: death within 24 h, pregnancy, administration of TXA more than 3 h following injury, and routine ultrasound surveillance for deep venous thrombosis. Incidence of VTE was the primary outcome. Secondary outcomes included MI, CVA, and death. A power analysis found that a total of 830 patients were needed to detect a true difference in VTE risk. 1333 patients (TXA = 887, No-TXA = 446 patients) from 17 centers were enrolled. There were no differences in age, shock index, Glasgow coma score, pelvis/extremity abbreviated injury score, or paralysis. Injury severity score was higher in the No-TXA group. Incidence of VTE, MI, or CVA was similar between the groups. The TXA group required significantly less transfusion (P < 0.001 for all products) and had a lower mortality [adjusted odds ratio 0.67 (95% confidence interval 0.45-0.98)]. Despite having a higher extremity/pelvis abbreviated injury score, results did not change when evaluating only patients with blunt injury. Use of TXA in bleeding, injured patients is not associated with VTE, MI, or CVA but is associated with a lower transfusion need and mortality.

Tranexamic Acid During Prehospital Transport in Patients at Risk for Hemorrhage After Injury: A Double-blind, Placebo-Controlled, Randomized Clinical Trial

IMPORTANCE

In-hospital administration of tranexamic acid after injury improves outcomes in patients at risk for hemorrhage. Data demonstrating the benefit and safety of the pragmatic use of tranexamic acid in the prehospital phase of care are lacking for these patients.

OBJECTIVE

To assess the effectiveness and safety of tranexamic acid administered before hospitalization compared with placebo in injured patients at risk for hemorrhage.

DESIGN, SETTING, AND PARTICIPANTS

This pragmatic, phase 3, multicenter, double-blind, placebo-controlled, superiority randomized clinical trial included injured patients with prehospital hypotension (systolic blood pressure ≤90 mm Hg) or tachycardia (heart rate ≥110/min) before arrival at 1 of 4 US level 1 trauma centers, within an estimated 2 hours of injury, from May 1, 2015, through October 31, 2019.

INTERVENTIONS

Patients received 1 g of tranexamic acid before hospitalization (447 patients) or placebo (456 patients) infused for 10 minutes in 100 mL of saline. The randomization scheme used prehospital and in-hospital phase assignments, and patients administered tranexamic acid were allocated to abbreviated, standard, and repeat bolus dosing regimens on trauma center arrival.

MAIN OUTCOMES AND MEASURES

The primary outcome was 30-day all-cause mortality.

RESULTS

In all, 927 patients (mean [SD] age, 42 [18] years; 686 [74.0%] male) were eligible for prehospital enrollment (460 randomized to tranexamic acid intervention; 467 to placebo intervention). After exclusions, the intention-to-treat study cohort comprised 903 patients: 447 in the tranexamic acid arm and 456 in the placebo arm. Mortality at 30 days was 8.1% in patients receiving tranexamic acid compared with 9.9% in patients receiving placebo (difference, -1.8%; 95% CI, -5.6% to 1.9%; P = .17). Results of Cox proportional hazards regression analysis, accounting for site, verified that randomization to tranexamic acid was not associated with a significant reduction in 30-day mortality (hazard ratio, 0.81; 95% CI, 0.59-1.11, P = .18). Prespecified dosing regimens and post-hoc subgroup analyses found that prehospital tranexamic acid were associated with significantly lower 30-day mortality. When comparing tranexamic acid effect stratified by time to treatment and qualifying shock severity in a post hoc comparison, 30-day mortality was lower when tranexamic acid was administered within 1 hour of injury (4.6% vs 7.6%; difference, -3.0%; 95% CI, -5.7% to -0.3%; P < .002). Patients with severe shock (systolic blood pressure ≤70 mm Hg) who received tranexamic acid demonstrated lower 30-day mortality compared with placebo (18.5% vs 35.5%; difference, -17%; 95% CI, -25.8% to -8.1%; P < .003).

CONCLUSIONS AND RELEVANCE

In injured patients at risk for hemorrhage, tranexamic acid administered before hospitalization did not result in significantly lower 30-day mortality. The prehospital administration of tranexamic acid after injury did not result in a higher incidence of thrombotic complications or adverse events. Tranexamic acid given to injured patients at risk for hemorrhage in the prehospital setting is safe and associated with survival benefit in specific subgroups of patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02086500.

Unjustified Administration in Liberal Use of Tranexamic Acid in Trauma Resuscitation

BACKGROUND

Early administration of tranexamic acid (TXA) has been widely implemented for the treatment of presumed hyperfibrinolysis in hemorrhagic shock. We aimed to characterize the liberal use of TXA and whether unjustified administration was associated with increased venous thrombotic events (VTEs).

METHODS

We identified injured patients who received TXA between January 2016 and January 2018 by querying our Level 1 trauma center's registry. We retrospectively reviewed medical records and radiologic images to classify whether patients had a hemorrhagic injury that would have benefited from TXA (justified) or not (unjustified).

RESULTS

Ninety-five patients received TXA for traumatic injuries, 42.1% were given by emergency medical services. TXA was considered unjustified in 35.8% of the patients retrospectively and in 52% of the patients when given by emergency medical services. Compared with unjustified administration, patients in the justified group were younger (47.6 versus 58.4; P = 0.02), more hypotensive in the field (systolic blood pressure: 107 ± 31 versus 137 ± 32 mm Hg; P < 0.001) and in the emergency department (systolic blood pressure: 97 ± 27 versus 128 ± 27; P < 0.001), and more tachycardic in emergency department (heart rate: 99 ± 29 versus 88 ± 19; P = 0.04). The justified group also had higher injury severity score (median 24 versus 11; P < 0.001), was transfused more often (81.7% versus 20.6%; P < 0.001), and had higher in-hospital mortality (39.3% versus 2.9%; P < 0.001), but there was no difference in the rate of VTE (8.2% versus 5.9%).

CONCLUSIONS

Our results highlight a high rate of unjustified administration, especially in the prehospital setting. Hypotension and tachycardia were indications of correct use. Although we did not observe a difference in VTE rates between the groups, though, our study was underpowered to detect a difference. Cautious implementation of TXA in resuscitation protocols is encouraged in the meantime. Nonetheless, adverse events associated with unjustified TXA administration should be further evaluated.

[Hyperfibrinolysis after Resuscitation due to Acute Pulmonary Artery Embolism]

In an 81-year-old patient, acute hemodynamic instability requiring resuscitation occurred during an elective transurethral prostate resection. The procedure was ended prematurely and after ROSC a CT diagnosis was carried out, which confirmed the suspected diagnosis of fulminant pulmonary embolism. Anticoagulant therapy with heparin was initiated. About two hours after admission to the intensive care unit, hemorrhage requiring massive transfusion developed, which according to viscoelastometric diagnostics was most likely due to fulminant hyperfibrinolysis. This case report describes the pathophysiology of so-called post-cardiac arrest coagulopathy and discusses the use of antifibrinolytic therapy in patients with thrombotic complications such as pulmonary artery embolism.

Viscoelastic testing in combat resuscitation: Is it time for a new standard?

BACKGROUND

Traumatic hemorrhage and coagulopathy represent major sources of morbidity and mortality on the modern battlefield. Viscoelastic testing (VET) offers a potentially more personalized approach to resuscitation. We sought to evaluate outcomes of combat trauma patients who received VET-guided resuscitation compared with standard balanced blood product resuscitation.

METHODS

Retrospective analysis of the Department of Defense Trauma Registry, 2008 to 2016 was performed. Multivariate logistic regression analyses of all adult patients initially presenting to NATO Role III facilities who required blood products were performed to identify factors associated with VET-guided resuscitation and mortality. A propensity score matched comparison of outcomes in patient cohorts treated at VET versus non-VET Role III facilities was performed.

RESULTS

There are 3,320 patients, predominately male (98%), median age ranges from 25 years to 29 years, Injury Severity Score of 18.8, with a penetrating injury (84%) were studied. Overall mortality was 9.7%. Five hundred ninety-four patients had VET during their initial resuscitation. After adjusting for confounders, VET during initial resuscitation was independently associated with decreased mortality (odds ratio, 0.63; p = 0.04). Propensity analysis confirmed this survival advantage with a 57% reduction in overall mortality (7.3% vs. 13.1%; p = 0.001) for all patients requiring blood products.

CONCLUSION

Viscoelastic testing offers the possibility of a product-specific resuscitation for critically injured patients requiring transfusion in combat settings. Routine VET may be superior to non-VET-guided resuscitation for combat trauma victims.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Dense and dangerous: The tissue plasminogen activator-resistant fibrinolysis shutdown phenotype is due to abnormal fibrin polymerization

BACKGROUND

Both hyperfibrinolysis and fibrinolysis shutdown can occur after severe trauma. The subgroup of trauma patients with fibrinolysis shutdown resistant to tissue plasminogen activator (t-PA)-mediated fibrinolysis have increased mortality. Fibrin polymerization and structure may influence fibrinolysis subgroups in trauma, but fibrin architecture has not been characterized in acutely injured subjects. We hypothesized that fibrin polymerization measured in situ will correlate with fibrinolysis subgroups.

METHODS

Blood samples were collected from trauma patients and noninjured controls. We selected samples across a range of fibrinolysis phenotypes (shutdown, physiologic, hyperfibrinolysis) and t-PA sensitivities (sensitive, physiologic, resistant) determined by thrombelastography. Plasma clots were created in situ with fluorescent fibrinogen and imaged using confocal microscopy for analysis of clot architecture in three dimensions. For each clot, we quantified the fiber resolvability, a metric of fiber distinctness or clarity, by mapping the variance of fluorescence intensity relative to background fluorescence. We also determined clot porosity by measuring the size and distribution of the gaps between fibrin fibers in three-dimensional space. We compared these measures across fibrinolysis subgroups.

RESULTS

Fiber resolvability was significantly lower in all trauma subgroups compared with controls (n = 35 and 5, respectively; p < 0.05). We observed markedly different patterns of fibrin architecture among trauma patients stratified by fibrinolysis subgroup. Subjects with t-PA-resistant fibrinolysis shutdown exhibited abnormal, densely packed fibrin clots nearly devoid of pores. Individuals with t-PA-hypersensitive fibrinolysis shutdown had highly irregular clots with pores as large as 2500 μm to 20,000 μm, versus 78 μm to 1250 μm in noninjured controls.

CONCLUSION

Fiber resolvability was significantly lower in trauma patients than controls, and subgroups of fibrinolysis differ in the porosity of the fibrin clot structure. The dense fibrin network in the t-PA-resistant group may prevent access to plasmin, suggesting a mechanism for thrombotic morbidity after injury.

Emergency Transfusions

Successful emergency transfusions require early recognition and activation of resources to minimize treatment delays. The initial goals should focus on replacement of blood in a balanced fashion. There is an ongoing debate regarding the best approach to transfusions, with some advocating for resuscitation with a fixed ratio of blood products and others preferring to use viscoelastic assays to guide transfusions. Whole-blood transfusion also is a debated strategy. Despite these different approaches, it generally is accepted that transfusions should be started early and crystalloid infusions limited. As hemodynamic stability is restored, endpoints of resuscitation should be used to guide the resuscitation.

Tracing the Lines: A Review of Viscoelastography for Emergency Medicine Clinicians

BACKGROUND

Viscoelastography (VE) is an established method to identify coagulopathies in various disease processes. Clinical decisions can be made with real-time tracings and quantitative values at the bedside. Thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) have been utilized in several disease states with clinical varying success.

OBJECTIVES

This review will summarize the literature and provide recommendations pertaining to major disease processes where VE may be beneficial, including trauma, anticoagulation reversal, liver disease, acute ischemic stroke, and acquired brain injuries.

DISCUSSION

VE has a role in many emergency medicine patients encountered by clinicians. Reduced mortality, decreased blood product utilization, and prognostication ability makes VE an intriguing tool that can be utilized by providers to improve patient care.

CONCLUSION

This review serves as a way for emergency medicine clinicians to utilize VE in their practice and provides an insightful literature overview.

TEG Lysis Shutdown Represents Coagulopathy in Bleeding Trauma Patients: Analysis of the PROPPR Cohort

BACKGROUND

Thrombelastography (TEG) fibrinolysis shutdown after trauma is associated with increased mortality due to hypercoagulability-associated organ failure. However, a lack of mechanistic data has precluded the development of novel interventions to treat shutdown.

OBJECTIVES

To define the pathophysiology of TEG shutdown in severely injured, bleeding patients through secondary analysis of the PROPPR trial.

METHODS

Fibrinolysis was characterized in PROPPR subjects using admission TEG lysis at 30 min (LY30) or plasmin-antiplasmin (PAP) levels. LY30 categories were low (<0.9%), moderate (0.9-2.9%), or high (≥ 3%). PAP was classified as low (<1,500 μg/L), moderate (1,500-20,000 μg/L), or high (>20,000 μg/L). Demographics, outcomes, admission TEG values, platelet count and function, standard coagulation tests, and coagulation proteins were compared.

RESULTS

Five hundred forty-seven patients had TEG data and 549 patients had PAP data available. Low LY30 was associated with reduced platelet count and aggregation, poorer TEG clot formation, prolonged clotting times, and reduced fibrinogen and alpha2 antiplasmin. Compared to moderate PAP, low PAP subjects had similar platelet parameters, TEG values, fibrinogen, and alpha2 antiplasmin, but reduced tPA, and elevated PAI-1. D-Dimer values increased as PAP increased, however patients with low LY30 had elevated D-Dimer compared with moderate LY30 patients. Most low LY30 deaths were due to TBI (45%) and hemorrhage (42%) versus one of each cause (TBI, hemorrhage, MOF) in low PAP patients.

CONCLUSIONS

Low TEG LY30 does not reflect shutdown of enzymatic fibrinolysis with hypercoagulability, but rather a coagulopathic state of moderate fibrinolysis with fibrinogen consumption and platelet dysfunction that is associated with poor outcomes.

Biological mechanisms and individual variation in fibrinolysis after major trauma

Objective

To understand more about the individual variation in the time course of fibrinolysis following major injury and to assess the potential for stratification of trauma patients for tranexamic acid (TXA) therapy.

Methods

A historical dataset (from 2004) was used, consisting of samples from 52 injured patients attended by a medical prehospital system. Blood samples were taken at the incident scene, on arrival in the emergency department, 2.5 hours after hospital arrival and 5 hours after hospital arrival. From the study database, we extracted values for tissue-type plasminogen activator (tPA; an activator of fibrinolysis), one of the plasminogen activator inhibitors (PAI-1; as a natural inhibitor of fibrinolysis) and D-dimer (as a marker of the extent of fibrinolysis).

Results

The changes over time in median tPA and PAI-1 were mirror images, with initial high tPA levels which then rapidly decreased and low initial PAI-1 levels which slowly increased. There were high levels of fibrinolytic activity (D-dimer) throughout. This pattern was present in patients across a broad range of injury severities.

Conclusions

After major trauma, there seems to be an early ‘antifibrinolytic gap’ with the natural antifibrinolytic system lagging several hours behind the natural profibrinolytics. An early dose of exogenous antifibrinolytic (TXA) might have its effect by filling this gap. The finding that tPA and subsequent clot breakdown (illustrated by D-dimer formation) are raised in a broad range of patients, with little correlation between the initial fibrinolytic response and markers of injury severity, may be the reason that TXA is effective across a broad range of injured patients.

Tranexamic Acid for Acute Hemorrhage: A Narrative Review of Landmark Studies and a Critical Reappraisal of Its Use Over the Last Decade

The publication of the Clinical Randomization of an Antifibrinolytic in Significant Hemorrhage-2 (CRASH-2) study and its intense dissemination prompted a renaissance for the use of the antifibrinolytic agent tranexamic acid (TXA) in acute trauma hemorrhage. Subsequent studies led to its widespread use as a therapeutic as well as prophylactic agent across different clinical scenarios involving bleeding, such as trauma, postpartum, and orthopedic surgery. However, results from the existing studies are confounded by methodological and statistical ambiguities and are open to varied interpretations. Substantial knowledge gaps remain on dosing, pharmacokinetics, mechanism of action, and clinical applications for TXA. The risk for potential thromboembolic complications with the use of TXA must be balanced against its clinical benefits. The present article aims to provide a critical reappraisal of TXA use over the last decade and a "thought exercise" in the potential downsides of TXA. A more selective and individualized use of TXA, guided by extended and functional coagulation assays, is advocated in the context of the evolving concept of precision medicine.

Trauma-targeted delivery of tranexamic acid improves hemostasis and survival in rat liver hemorrhage model

BACKGROUND

Trauma-associated hemorrhage and coagulopathy remain leading causes of mortality. Such coagulopathy often leads to a hyperfibrinolytic phenotype where hemostatic clots become unstable because of upregulated tissue plasminogen activator (tPA) activity. Tranexamic acid (TXA), a synthetic inhibitor of tPA, has emerged as a promising drug to mitigate fibrinolysis. TXA is US Food and Drug Administration-approved for treating heavy menstrual and postpartum bleeding, and has shown promise in trauma treatment. However, emerging reports also implicate TXA for off-target systemic coagulopathy, thromboembolic complications, and neuropathy.

OBJECTIVE

We hypothesized that targeted delivery of TXA to traumatic injury site can enable its clot-stabilizing action site-selectively, to improve hemostasis and survival while avoiding off-target effects. To test this, we used liposomes as a model delivery vehicle, decorated their surface with a fibrinogen-mimetic peptide for anchorage to active platelets within trauma-associated clots, and encapsulated TXA within them.

METHODS

The TXA-loaded trauma-targeted nanovesicles (T-tNVs) were evaluated in vitro in rat blood, and then in vivo in a liver trauma model in rats. TXA-loaded control (untargeted) nanovesicles (TNVs), free TXA, or saline were studied as comparison groups.

RESULTS

Our studies show that in vitro, the T-tNVs could resist lysis in tPA-spiked rat blood. In vivo, T-tNVs maintained systemic safety, significantly reduced blood loss and improved survival in the rat liver hemorrhage model. Postmortem evaluation of excised tissue from euthanized rats confirmed systemic safety and trauma-targeted activity of the T-tNVs.

CONCLUSION

Overall, the studies establish the potential of targeted TXA delivery for safe injury site-selective enhancement and stabilization of hemostatic clots to improve survival in trauma.