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

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.

ICU Management of Trauma Patients

OBJECTIVES

To describe the current state of the art regarding management of the critically ill trauma patient with an emphasis on initial management in the ICU.

DATA SOURCES AND STUDY SELECTION

A PubMed literature review was performed for relevant articles in English related to the management of adult humans with severe trauma. Specific topics included airway management, hemorrhagic shock, resuscitation, and specific injuries to the chest, abdomen, brain, and spinal cord.

DATA EXTRACTION AND DATA SYNTHESIS

The basic principles of initial management of the critically ill trauma patients include rapid identification and management of life-threatening injuries with the goal of restoring tissue oxygenation and controlling hemorrhage as rapidly as possible. The initial assessment of the patient is often truncated for procedures to manage life-threatening injuries. Major, open surgical procedures have often been replaced by nonoperative or less-invasive approaches, even for critically ill patients. Consequently, much of the early management has been shifted to the ICU, where the goal is to continue resuscitation to restore homeostasis while completing the initial assessment of the patient and watching closely for failure of nonoperative management, complications of procedures, and missed injuries.

CONCLUSIONS

The initial management of critically ill trauma patients is complex. Multiple, sometimes competing, priorities need to be considered. Close collaboration between the intensivist and the surgical teams is critical for optimizing patient outcomes.

Management of Severe Bleeding in Patients Treated With Oral Anticoagulants: Proceedings Monograph From the Emergency Medicine Cardiac Research and Education Group-International Multidisciplinary Severe Bleeding Consensus Panel October 20, 2018

In this Emergency Medicine Cardiac Research and Education Group (EMCREG)-International Proceedings Monograph from the October 20, 2018, EMCREG-International Multidisciplinary Consensus Panel on Management of Severe Bleeding in Patients Treated With Oral Anticoagulants held in Orlando, FL, you will find a detailed discussion regarding the treatment of patients requiring anticoagulation and the reversal of anticoagulation for patients with severe bleeding. For emergency physicians, critical care physicians, hospitalists, cardiologists, internists, surgeons, and family physicians, the current approach and disease indications for treatment with anticoagulants such as coumadin, factor IIa, and factor Xa inhibitors are particularly relevant. When a patient treated with anticoagulants presents to the emergency department, intensive care unit, or operating room with severe, uncontrollable bleeding, achieving rapid, controlled hemostasis is critically important to save the patient's life. This EMCREG-International Proceedings Monograph contains multiple sections reflecting critical input from experts in Emergency Cardiovascular Care, Prehospital Emergency Medical Services, Emergency Medicine Operations, Hematology, Hospital Medicine, Neurocritical Care, Cardiovascular Critical Care, Cardiac Electrophysiology, Cardiology, Trauma and Acute Care Surgery, and Pharmacy. The first section provides a description of the current indications for the treatment of patients using oral anticoagulants including coumadin, the factor IIa (thrombin) inhibitor dabigatran, and factor Xa inhibitors such as apixaban and rivaroxaban. In the remaining sections, the treatment of patients presenting to the hospital with major bleeding becomes the focus. The replacement of blood components including red blood cells, platelets, and clotting factors is the critically important initial treatment for these individuals. Reversing the anticoagulated state is also necessary. For patients treated with coumadin, infusion of vitamin K helps to initiate the process of protein synthesis for the vitamin K-dependent coagulation proteins II, VII, IX, and X and the antithrombotic protein C and protein S. Repletion of clotting factors for the patient with 4-factor prothrombin complex concentrate, which includes factors II (prothrombin), VII, IX, and X and therapeutically effective concentrations of the regulatory proteins (protein C and S), provides real-time ability to slow bleeding. For patients treated with the thrombin inhibitor dabigatran, treatment using the highly specific, antibody-derived idarucizumab has been demonstrated to reverse the hypocoagulable state of the patient to allow blood clotting. In May 2018, andexanet alfa was approved by the US Food and Drug Administration to reverse the factor Xa anticoagulants apixaban and rivaroxaban in patients with major bleeding. Before the availability of this highly specific agent, therapy for patients treated with factor Xa inhibitors presenting with severe bleeding usually included replacement of lost blood components including red blood cells, platelets, and clotting factors and 4-factor prothrombin complex concentrate, or if not available, fresh frozen plasma. The evaluation and treatment of the patient with severe bleeding as a complication of oral anticoagulant therapy are discussed from the viewpoint of the emergency physician, neurocritical and cardiovascular critical care intensivist, hematologist, trauma and acute care surgeon, hospitalist, cardiologist, electrophysiologist, and pharmacist in an approach we hope that the reader will find extremely practical and clinically useful. The clinician learner will also find the discussion of the resumption of oral anticoagulation for the patient with severe bleeding after effective treatment important because returning the patient to an anticoagulated state as soon as feasible and safe prevents thrombotic complications. Finally, an EMCREG-International Severe Bleeding Consensus Panel algorithm for the approach to management of patients with life-threatening oral anticoagulant-associated bleeding is provided for the clinician and can be expanded in size for use in a treatment area such as the emergency department or critical care unit.

Fibrinolysis Shutdown in Trauma: Historical Review and Clinical Implications

Despite over a half-century of recognizing fibrinolytic abnormalities after trauma, we remain in our infancy in understanding the underlying mechanisms causing these changes, resulting in ineffective treatment strategies. With the increased utilization of viscoelastic hemostatic assays (VHAs) to measure fibrinolysis in trauma, more questions than answers are emerging. Although it seems certain that low fibrinolytic activity measured by VHA is common after injury and associated with increased mortality, we now recognize subphenotypes within this population and that specific cohorts arise depending on the specific time from injury when samples are collected. Future studies should focus on these subtleties and distinctions, as hypofibrinolysis, acute shutdown, and persistent shutdown appear to represent distinct, unique clinical phenotypes, with different pathophysiology, and warranting different treatment strategies.

Severely injured trauma patients with admission hyperfibrinolysis: Is there a role of tranexamic acid? Findings from the PROPPR trial

INTRODUCTION

Administration of tranexamic acid (TXA) in coagulopathy of trauma gained popularity after the CRASH-2 trial. The aim of our analysis was to analyze the role of TXA in severely injured trauma patients with admission hyperfibrinolysis.

METHODS

We reviewed the prospectively collected Pragmatic, Randomized Optimal Platelet and Plasma Ratios database. We included patients with admission hyperfibrinolysis (Ly30 >3%) on thromboelastography. Patients were stratified into two groups (TXA and No-TXA) and were matched in 1:2 ratio using propensity score matching for demographics, admission vitals, and injury severity. Primary outcome measures were 6-, 12-, and 24-hour and 30-day mortality; 24-hour transfusion requirements; time to achieve hemostasis; and rebleeding after hemostasis requiring intervention. Secondary outcome measures were thrombotic complications.

RESULTS

We analyzed 680 patients. Of those, 118 had admission hyperfibrinolysis, and 93 patients (TXA: 31 patients; No-TXA: 62 patients) were matched. Matched groups were similar in age (p = 0.33), gender (p = 0.84), race (p = 0.81), emergency department (ED) Glasgow Coma Scale (p = 0.34), ED systolic blood pressure (p = 0.28), ED heart rate (p = 0.43), mechanism of injury (p = 0.45), head Abbreviated Injury Scale score (p = 0.68), injury severity score (p = 0.56), and blood products ratio (p = 0.44). Patients who received TXA had a lower 6-hour mortality rate (34% vs. 13%, p = 0.04) and higher 24-hour transfusion of plasma (15 vs. 10 units, p = 0.03) compared with the No-TXA group. However, there was no difference in 12-hour (p = 0.24), 24-hour (p = 0.25), and 30-day mortality (p = 0.82). Similarly, there was no difference in 24-hour transfusion of RBC (p = 0.11) or platelets (p = 0.13), time to achieve hemostasis (p = 0.65), rebleeding requiring intervention (p = 0.13), and thrombotic complications (p = 0.98).

CONCLUSION

Tranexamic acid was associated with increased 6-hour survival but does not improve long-term outcomes in severely injured trauma patients with hemorrhage who develop hyperfibrinolysis. Moreover, TXA administration was not associated with thrombotic complications. Further randomized clinical trials will identify the subset of trauma patients who may benefit from TXA.

LEVEL OF EVIDENCE

Therapeutic study, level III.

The “Death Diamond”: Death beyond Trauma

Thromboelastography (TEG) has become a critical tool for the diagnosis, assessment, and management of hyperfibrinolysis and coagulopathy in trauma. In 2015, Chapman et al. of the Denver group coined the term “Death Diamond” (DD) to describe a TEG tracing identified in a unique trauma population. The DD was associated with a 100 per cent positive predictive value for mortality. Given the potential prognostic implications and resource savings associated with validating the DD as a marker of futile care, we sought to further evaluate DD outcomes. A retrospective review of 6850 TEGs, 34 patients (24 trauma and 10 nontrauma), displayed a DD tracing. Through invasive procedures and transfusions, nine DD tracing “normalized,” but, ultimately, this did not impact the outcome because the DD had a positive predictive value of 100 per cent for mortality in both populations. The median survival time in trauma patients was two hours compared with seven hours in nontrauma patients. Overall, this study further validates the predictive value of the DD in a trauma population while also serving as an assessment of the DD in a nontrauma population. Given these findings, a DD may prove to be an indicator of futile care. Further multicenter studies should be conducted to confirm these results.

Does Tranexamic Acid Improve Clot Strength in Severely Injured Patients Who Have Elevated Fibrin Degradation Products and Low Fibrinolytic Activity, Measured by Thrombelastography?

BACKGROUND

Elevated d-dimers in injured patients with paradoxically low fibrinolysis activity measured by viscoelastic assays have been speculated to be "occult" fibrinolysis. However, an alternative explanation is that these patients have previously activated their fibrinolytic system and have shut it down by the time of blood draw, and would gain no benefit in clot strength with tranexamic acid (TXA). We hypothesize that TXA will not increase clot strength in injured patients with low fibrinolytic activity measured by thrombelastography (TEG), despite biomarkers of fibrinolysis activation.

STUDY DESIGN

Three TEG assays (rapid, tissue plasminogen activator, and functional fibrinogen) were run on trauma patients. The tissue plasminogen activator TEG served as a functional assay to quantify depletion of fibrinolysis inhibitors (DFI). Patients were stratified by DFI vs non-DFI and then by rapid TEG lysis at 30 minutes phenotype cutoffs. Response to TXA was evaluated with functional fibrinogen TEG by calculating percent change in clot strength with the addition of exogenous TXA in the TEG cup.

RESULTS

Six hundred and thirty patients with a median new injury severity score of 20 were analyzed. Depletion of fibrinolysis inhibitors was present in 116 (18%). The DFI patients had significantly increased d-dimer (p < 0.001) and lower fibrinogen (p < 0.001). The DFI patients had increased rates of massive transfusion (33% vs 3.3%; p < 0.001) and mortality (40% vs 6.2%; p < 0.001). Among DFI patients, TXA significantly improved fibrin clot strength with hyperfibrinolysis (+19% clot strength; p < 0.001) but not with shutdown (+1.2%) or physiologic (-2.5%).

CONCLUSIONS

Patients with DFI have multiple abnormalities of their coagulation system, but only DFI patients with hyperfibrinolysis have improved fibrin clot strength with TXA.

Trauma-induced coagulopathy: The past, present, and future

Trauma remains a leading cause of death worldwide, and most early preventable deaths in both the civilian and military settings are due to uncontrolled hemorrhage, despite paradigm advances in modern trauma care. Combined tissue injury and shock result in hemostatic failure, which has been identified as a multidimensional molecular, physiologic and clinical disorder termed trauma-induced coagulopathy (TIC). Understanding the biology of TIC is of utmost importance, as it is often responsible for uncontrolled bleeding, organ failure, thromboembolic complications, and death. Investigations have shown that TIC is characterized by multiple phenotypes of impaired hemostasis due to altered biology in clot formation and breakdown. These coagulopathies are attributable to tissue injury and shock, and encompass underlying endothelial, immune and inflammatory perturbations. Despite the recognition and identification of multiple mechanisms and mediators of TIC, and the development of targeted treatments, the mortality rates and associated morbidities due to hemorrhage after injury remain high. The purpose of this review is to examine the past and present understanding of the multiple distinct but highly integrated pathways implicated in TIC, in order to highlight the current knowledge gaps and future needs in this evolving field, with the aim of reducing morbidity and mortality after injury.

The role of evidence-based algorithms for rotational thromboelastometry-guided bleeding management

Rotational thromboelastometry (ROTEM) is a point-of-care viscoelastic method and enables to assess viscoelastic profiles of whole blood in various clinical settings. ROTEM-guided bleeding management has become an essential part of patient blood management (PBM) which is an important concept in improving patient safety. Here, ROTEM testing and hemostatic interventions should be linked by evidence-based, setting-specific algorithms adapted to the specific patient population of the hospitals and the local availability of hemostatic interventions. Accordingly, ROTEM-guided algorithms implement the concept of personalized or precision medicine in perioperative bleeding management (‘theranostic’ approach). ROTEM-guided PBM has been shown to be effective in reducing bleeding, transfusion requirements, complication rates, and health care costs. Accordingly, several randomized-controlled trials, meta-analyses, and health technology assessments provided evidence that using ROTEM-guided algorithms in bleeding patients resulted in improved patient’s safety and outcomes including perioperative morbidity and mortality. However, the implementation of ROTEM in the PBM concept requires adequate technical and interpretation training, education and logistics, as well as interdisciplinary communication and collaboration.

Overresuscitation with plasma is associated with sustained fibrinolysis shutdown and death in pediatric traumatic brain injury

BACKGROUND

Elevated International Normalized Ratio (INR) is a marker of poor outcome but not necessarily bleeding or clinical coagulopathy in injured children. Conversely, children with traumatic brain injury (TBI) tend to be hypercoagulable based on rapid thromboelastography (rTEG) parameters. Many clinicians continue to utilize INR as a treatment target.

METHODS

Prospective observational study of severely injured children age < 18 with rTEG on arrival and daily thereafter for up to 7 days. Standard rTEG definitions of hyperfibrinolysis (LY30 ≥ 3), fibrinolysis shutdown (SD) (LY30 ≤ 0.8), and normal (LY30 = 0.9-2.9) were applied. The first 24-hour blood product transfusion volumes were documented. Abbreviated Injury Scale score ≥ 3 defined severe TBI. Sustained SD was defined as two consecutive rTEG with SD and no subsequent normalization. Primary outcomes were death and functional disability, based on functional independence measure score assessed at discharge.

RESULTS

One hundred one patients were included: median age, 8 years (interquartile range, 4-12 years); Injury Severity Score, 25 (16-30); 72% blunt mechanism; 47% severe TBI; 16% mortality; 45% discharge disability. Neither total volume nor any single product volume transfused (mL/kg; all p > 0.1) differed between TBI and non-TBI groups. On univariate analysis, transfusion of packed red blood cells (p = 0.016), plasma (p < 0.001), and platelets (p = 0.006) were associated with sustained SD; however, in a regression model that included all products (mL/kg) and controlled for severe TBI (head Abbreviated Injury Scale score ≥ 3), admission INR, polytrauma, and clinical bleeding, only plasma remained an independent predictor of sustained SD (odds ratio, 1.17; p = 0.031). Patients with both severe TBI and plasma transfusion had 100% sustained SD, 75% mortality, and 100% disability in survivors. Admission INR was elevated in TBI patients, but did not correlate with rTEG activated clotting time (p = NS) and was associated with sustained SD (p = 0.006).

CONCLUSION

Plasma transfusion is independently associated with sustained fibrinolysis SD. Severe TBI is also associated with sustained SD; the combined effect of plasma transfusion and severe TBI is associated with extremely poor prognosis. Plasma transfusion should not be targeted to INR thresholds but rather to rTEG activated clotting time and clinical bleeding.

LEVEL OF EVIDENCE

Prognostic and epidemiological study, level III.

Mortality and Thrombosis in Injured Adults Receiving Tranexamic Acid in the Post-CRASH-2 Era

Introduction

The CRASH-2 trial demonstrated that tranexamic acid (TXA) reduced mortality with no increase in adverse events in severely injured adults. TXA has since been widely used in injured adults worldwide. Our objective was to estimate mortality and adverse events in adults with trauma receiving TXA in studies published after the CRASH-2 trial.

Methods

We systematically searched PubMed, Embase, MicroMedex, and ClinicalTrials.gov for studies that included injured adults who received TXA and reported mortality and/or adverse events. Two reviewers independently assessed study eligibility, abstracted data, and assessed the risk of bias. We conducted meta-analyses using random effects models to estimate the incidence of mortality at 28 or 30 days and in-hospital thrombotic events.

Results

We included 19 studies and 13 studies in the systematic review and meta-analyses, respectively. The pooled incidence of mortality at 28 or 30 days (five studies, 1538 patients) was 10.1% (95% confidence interval [CI], 7.8–12.4%) (vs 14.5% [95% CI, 13.9–15.2%] in the CRASH-2 trial), and the pooled incidence of in-hospital thrombotic events (nine studies, 1656 patients) was 5.9% (95% CI, 3.3–8.5%) (vs 2.0% [95% CI, 1.8–2.3%] in the CRASH-2 trial).

Conclusion

Compared to the CRASH-2 trial, adult trauma patients receiving TXA identified in our systematic review had a lower incidence of mortality at 28 or 30 days, but a higher incidence of in-hospital thrombotic events. Our findings neither support nor refute the findings of the CRASH-2 trial but suggest that incidence rates in adults with trauma in settings outside of the CRASH-2 trial may be different than those observed in the CRASH-2 trial.

Tranexamic acid in severe trauma patients managed in a mature trauma care system

BACKGROUND

Tranexamic acid (TXA) use in severe trauma remains controversial notably because of concerns of the applicability of the CRASH-2 study findings in mature trauma systems. The aim of our study was to evaluate the outcomes of TXA administration in severely injured trauma patients managed in a mature trauma care system.

METHODS

We performed a retrospective study of data prospectively collected in the TraumaBase registry (a regional registry collecting the prehospital and hospital data of trauma patients admitted in six Level I trauma centers in Paris Area, France). In hospital mortality was compared between patients having received TXA or not in the early phase of resuscitation among those presenting an unstable hemodynamic state. Propensity score for TXA administration was calculated and results were adjusted for this score. Hemodynamic instability was defined by the need of packed red blood cells (pRBC) transfusion and/or vasopressor administration in the emergency room (ER).

RESULTS

Among patients meeting inclusion criteria (n = 1,476), the propensity score could be calculated in 797, and survival analysis could be achieved in 684 of 797. Four hundred seventy (59%) received TXA, and 327 (41%) did not. The overall hospital mortality rate was 25.7%. There was no effect of TXA use in the whole population but mortality was lowered by the use of TXA in patients requiring pRBC transfusion in the ER (hazard ratio, 0.3; 95% confidence interval, 0.3-0.6).

CONCLUSION

The use of TXA in the management of severely injured trauma patients, in a mature trauma care system, was not associated with reduction in the hospital mortality. An independent association with a better survival was found in a selected population of patients requiring pRBC transfusion in the ER.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Redefining postinjury fibrinolysis phenotypes using two viscoelastic assays

INTRODUCTION

Fibrinolysis was initially defined using rapid thrombelastography (rTEG). The cutoffs for the pathologic extremes of the fibrinolytic system, hyperfibrinolysis and shutdown, were both defined based on association with mortality. We propose to redefine these phenotypes for both TEG and for rotational thrombelastometry, the other commonly used viscoelastic assay.

METHODS

Rotational thrombelastometry, rTEG, and clinical data were prospectively collected on trauma patients admitted to an urban Level I trauma center from 2010 to 2016. Hyperfibrinolysis was defined as the Youden index from EXTEM-clot lysis index 60 minutes after clotting time (CLI60) and rTEG-fibrinolysis 30 minutes after achieving MA (LY30) for predicting massive transfusion (>10 red blood cell units, or death per 6 hours after injury) as a surrogate for severe bleeding. Patients identified as having hyperfibrinolysis were then removed from the data set, and the cutoff for fibrinolysis shutdown was derived as the optimal cutoff for predicting mortality in the remaining patients.

RESULTS

Overall, 216 patients (median age, 36 years (interquartile range, 27-49 years), 82% men, 58% blunt injury) were included. Of these, 16% required massive transfusion, and 12.5% died. Rapid thrombelastography phenotypes were redefined as hyperfibrinolysis: rTEG-LY30 greater than7.7%, physiologic rTEG-LY30 0.6% to7.6%, and shutdown rTEG-LY30 less than 0.6%. EXTEM-CLI60 fibrinolysis phenotypes were hyperfibrinolysis CLI60 less than 82%, physiologic (CLI60, 82-97.9%), and shutdown (CLI60 > 98%). Weighted kappa statistics revealed moderate agreement between rotational thrombelastometry- and rTEG-defined fibrinolysis (k = 0.51; 95% confidence interval, 0.39-0.63), with disagreement mostly in the shutdown and physiologic categories.

CONCLUSION

We confirmed the U-shaped distribution of death related to fibrinolysis system abnormalities. Both rTEG LY30 and EXTEM CLI60 can identify the spectrum of fibrinolytic phenotypes, have moderate agreement, and can be used to guide hemostatic resuscitation.

LEVEL OF EVIDENCE

Diagnostic study, level III.

Fibrinolysis in trauma patients: wide variability demonstrated by the Lysis Timer

Hyperfibrinolysis contributes to the pathophysiology of trauma-induced coagulopathy. At present, systematic administration of tranexamic acid (TXA) is recommended in all patients in the early phase of trauma. However, there is some debate regarding whether TXA is beneficial in all trauma patients. A rapid and accurate tool to diagnose hyperfibrinolysis may be useful for tailoring TXA treatment. We conducted a proof-of-concept study of consecutive adult trauma patients. A first blood sample was obtained at the time of pre-hospital care (T1). Patients received 1 g of TXA after T1. A second sample was obtained on arrival at the emergency unit (T2). We examined coagulation, fibrin and fibrinogen formation and degradation. Fibrinolysis was assessed by determining tissue plasminogen activator (t-PA) antigen and plasminogen activator inhibitor 1 (PAI-1) activity and global fibrinolysis capacity assay using a device developed by Hyphen BioMed: the Lysis Timer (GFC/LT). The study population consisted of 20 patients (42 ± 21 years, index of severity score 32 ± 21). Both coagulation and fibrinolysis were altered at T1. GFC/LT values exhibited hyperfibrinolysis only in five patients. Principal component analysis carried out at T1 showed two main axes of alteration. The major axis was related to coagulation, altered in all patients, while the second axis was related to fibrinolysis. GFC/LT was mainly influenced by PAI-1 activity while fibrin monomers were related to the severity of trauma. At T2, GFC/LT exhibited the marked effect of TXA on clot lysis time. In conclusion, GFC/LT demonstrated huge variation in the fibrinolytic response to trauma.

Plasma coadministration improves resuscitation with tranexamic acid or prothrombin complex in a porcine hemorrhagic shock model

BACKGROUND

Traumatic coagulopathy has now been well characterized and carries high rates of mortality owing to bleeding. A 'factor-based' resuscitation strategy using procoagulant drugs and factor concentrates in lieu of plasma is being used by some, but with little evidentiary support. We sought to evaluate and compare resuscitation strategies using combinations of tranexamic acid (TXA), prothrombin complex concentrate (PCC), and fresh frozen plasma (FFP).

METHODS

Sixty adult swine underwent 35% blood volume hemorrhage combined with a truncal ischemia-reperfusion injury to produce uniform shock and coagulopathy. Animals were randomized to control (n = 12), a single-agent group (TXA, n = 10; PCC, n = 8; or FFP, n = 6) or combination groups (TXA-FFP, n = 10; PCC-FFP, n = 8; TXA-PCC, n = 6). Resuscitation was continued to 6 hours. Key outcomes included hemodynamics, laboratory values, and rotational thromboelastometry. Results were compared between all groups, with additional comparisons between FFP and non-FFP groups.

RESULTS

All 60 animals survived to 6 hours. Shock was seen in all animals, with hypotension (mean arterial pressure, 44 mm Hg), tachycardia (heart rate, 145), acidosis (pH 7.18; lactate, 11), anemia (hematocrit, 17), and coagulopathy (fibrinogen, 107). There were clear differences between groups for mean pH (p = 0.02), international normalized ratio (p < 0.01), clotting time (CT; p < 0.01), lactate (p = 0.01), creatinine (p < 0.01), and fibrinogen (p = 0.02). Fresh frozen plasma groups had significantly improved resuscitation and clotting parameters (Figures), with lower lactate at 6.5 versus 8.4 (p = 0.04), and increased fibrinogen at 126 versus 95 (p < 0.01). Rotational thromboelastometry also demonstrated shortened CT at 60 seconds in the FFP group vs 65 seconds in the non-FFP group (p = 0.04).

CONCLUSION

When used to correct traumatic coagulopathy, combinations of FFP with TXA or PCC were superior in improving acidosis, coagulopathy, and CT than when these agents are given alone or in combination without plasma. Further validation of pure factor-based strategies is needed.

Position of the French Working Group on Perioperative Haemostasis (GIHP) on viscoelastic tests: What role for which indication in bleeding situations?

PURPOSE

Viscoelastic tests (VETs), thromboelastography (TEG^®) and thromboelastometry (ROTEM^®) are global tests of coagulation performed on whole blood. They evaluate the mechanical strength of a clot as it builds and develops after coagulation itself. The time required to obtain haemostasis results remains a major problem for clinicians dealing with bleeding, although some teams have developed a rapid laboratory response strategy. Indeed, the value of rapid point-of-care diagnostic devices such as VETs has increased over the years. However, VETs are not standardised and there are few recommendations from the learned societies regarding their use. In 2014, the recommendations of the International Society of Thrombosis and Haemostasis (ISTH) only concerned haemophilia. The French Working Group on Perioperative haemostasis (GIHP) therefore proposes to summarise knowledge on the clinical use of these techniques in the setting of emergency and perioperative medicine.

METHODS

A review of the literature.

PRINCIPAL FINDINGS

The role of the VETs seems established in the management of severe trauma and in cardiac surgery, both adult and paediatric. In other situations, their role remains to be defined: hepatic transplantation, postpartum haemorrhage, and non-cardiac surgery. They must be part of the global management of haemostasis based on algorithms defined in each centre and for each population of patients. Their position at the bedside or in the laboratory is a matter of discussion between clinicians and biologists.

CONCLUSION

VETs must be included in algorithms. In consultation with the biology laboratory, these devices should be situated according to the way each centre functions.