Primary Fibrinolysis Is Integral in the Pathogenesis of the Acute Coagulopathy of Trauma

Utility of rotational thromboelastometry for the diagnosis of asymptomatic hyperfibrinolysis secondary to anaphylaxis

We present a case of hyperfibrinolysis induced by oxaliplatin-derived anaphylactic shock, which was diagnosed with rotational thromboelastometry (ROTEM). A 57-year-old male patient underwent a second course of oxaliplatin (126 mg/m/course)-based chemotherapy for stage IV metastatic rectal cancer. Two minutes after the infusion of oxaliplatin, the patient lost consciousness and developed generalized urticarial lesions, followed by hemodynamic instability and respiratory insufficiency. He was diagnosed anaphylactic shock and transported to emergency department (ED) after intramuscular injection of 0.2 mg of adrenaline, an intravenous injection of 100 mg of hydrocortisone, and 500 mg of methylprednisolone. After arriving in the ED, the patient remained in shock and early resuscitation with administration of 5 mg of D-chlorpheniramine maleate and 20 mg of famotidine was performed. He recovered from his state of shock 30 min after the resuscitation. ROTEM findings showed fulminant hyperfibrinolysis with minimal changes in standard coagulation tests (SCTs) and no remarkable coagulopathy. Seven hours after the attack, he became asymptomatic and follow-up ROTEM revealed values within normal limits with the exception of sustained slight abnormalities of SCTs. He was discharged the next day without any signs of spontaneous bleeding and has continued his outpatient chemotherapy uneventfully. A review of the literature on anaphylaxis-induced hyperfibrinolysis and a discussion of the mechanism between anaphylactic shock and hyperfibrinolysis were performed. Although administration of tissue-type plasminogen activator can play a vital role in anaphylactic shock-induced hyperfibrinolysis, early effective resuscitation is imperative to prevent severe hemorrhagic complications. Therefore, ROTEM is a useful tool that can detect these dynamic changes faster and more accurately than SCTs.

Fibrinogen in traumatic haemorrhage: A narrative review

Haemorrhage in the setting of severe trauma is associated with significant morbidity and mortality. There is increasing awareness of the important role fibrinogen plays in traumatic haemorrhage. Fibrinogen levels fall precipitously in severe trauma and the resultant hypofibrinogenaemia is associated with poor outcomes. Hence, it has been postulated that early fibrinogen replacement in severe traumatic haemorrhage may improve outcomes, although, to date there is a paucity of high quality evidence to support this hypothesis. In addition there is controversy regarding the optimal method for fibrinogen supplementation. We review the current evidence regarding the role of fibrinogen in trauma, the rationale behind fibrinogen supplementation and discuss current research.

Pathophysiology of trauma-induced coagulopathy: disseminated intravascular coagulation with the fibrinolytic phenotype

In severe trauma patients, coagulopathy is frequently observed in the acute phase of trauma. Trauma-induced coagulopathy is coagulopathy caused by the trauma itself. The pathophysiology of trauma-induced coagulopathy consists of coagulation activation, hyperfibrino(geno)lysis, and consumption coagulopathy. These pathophysiological mechanisms are the characteristics to DIC with the fibrinolytic phenotype.

Acute traumatic coagulopathy and trauma-induced coagulopathy: an overview

Hemorrhage is the most important contributing factor of acute-phase mortality in trauma patients. Previously, traumatologists and investigators identified iatrogenic and resuscitation-associated causes of coagulopathic bleeding after traumatic injury, including hypothermia, metabolic acidosis, and dilutional coagulopathy that were recognized as primary drivers of bleeding after trauma. However, the last 10 years has seen a widespread paradigm shift in the resuscitation of critically injured patients, and there has been a dramatic evolution in our understanding of trauma-induced coagulopathy. Although there is no consensus regarding a definition or an approach to the classification and naming of trauma-associated coagulation impairment, trauma itself and/or traumatic shock-induced endogenous coagulopathy are both referred to as acute traumatic coagulopathy (ATC), and multifactorial trauma-associated coagulation impairment, including ATC and resuscitation-associated coagulopathy is recognized as trauma-induced coagulopathy. Understanding the pathophysiology of trauma-induced coagulopathy is vitally important, especially with respect to the critical issue of establishing therapeutic strategies for the management of patients with severe trauma.

Dynamics of fibrinogen in acute phases of trauma

Fibrinogen is a unique precursor of fibrin and cannot be compensated for by other coagulation factors. If plasma fibrinogen concentrations are insufficient, hemostatic clots cannot be formed with the appropriate firmness. In severe trauma patients, plasma fibrinogen concentrations decrease earlier and more frequently than other coagulation factors, predicting massive bleeding and death. We review the mechanisms of plasma fibrinogen concentration decrease, which include coagulation activation-induced consumption, hyper-fibrino(geno)lysis-induced degradation, and dilution by infusion/transfusion. Understanding the mechanisms of plasma fibrinogen concentration decrease in severe trauma patients is crucial.

S2'-subsite variations between human and mouse enzymes (plasmin, factor XIa, kallikrein) elucidate inhibition differences by tissue factor pathway inhibitor -2 domain1-wild-type, Leu17Arg-mutant and aprotinin

Essentials Current antifibrinolytics - aminocaproic acid and tranexamic acid-can cause seizures or renal injury. KD1L17R -KT , aprotinin and tranexamic acid were tested in a modified mouse tail-amputation model. S2'-subsite variations between human and mouse factor XIa result in vastly different inhibition profiles. KD1L17R -KT reduces blood loss and D-dimer levels in mouse with unobserved seizures or renal injury.

SUMMARY

Background Using tissue factor pathway inhibitor (TFPI)-2 Kunitz domain1 (KD1), we obtained a bifunctional antifibrinolytic molecule (KD1L17R -KT ) with C-terminal lysine (kringle domain binding) and P2'-residue arginine (improved specificity towards plasmin). KD1L17R -KT strongly inhibited human plasmin (hPm), with no inhibition of human kallikrein (hKLK) or factor XIa (hXIa). Furthermore, KD1L17R -KT reduced blood loss comparable to aprotinin in a mouse liver-laceration model of organ hemorrhage. However, effectiveness of these antifibrinolytic agents in a model of hemorrhage mimicking extremity trauma and their inhibition efficiencies for mouse enzymes (mPm, mKLK or mXIa) remain to be determined. Objective To determine potential differences in inhibition constants of various antifibrinolytic agents against mouse and human enzymes and test their effectiveness in a modified mouse tail-amputation hemorrhage model. Methods/Results Unexpectedly, mXIa was inhibited with ~ 17-fold increased affinity by aprotinin (Ki ~ 20 nm) and with measurable affinity for KD1L17R -KT (Ki ~ 3 μm); in contrast, KD1WT -VT inhibited hXIa or mXIa with similar affinity. Compared with hPm, mPm had ~ 3-fold reduced affinity, whereas species specificity for hKLK and mKLK was comparable for each inhibitor. S2'-subsite variations largely accounted for the observed differences. KD1L17R -KT and aprotinin were more effective than KD1WT -VT or tranexamic acid in inhibiting tPA-induced mouse plasma clot lysis. Further, KD1L17R -KT was more effective than KD1WT -VT and was comparable to aprotinin and tranexamic acid in reducing blood loss and D-dimer levels in the mouse tail-amputation model. Conclusions Inhibitor potencies differ between antifibrinolytic agents against human and mouse enzymes. KD1L17R -KT is effective in reducing blood loss in a tail-amputation model that mimics extremity injury.

Bleeding related to disturbed fibrinolysis

The components and reactions of the fibrinolysis system are well understood. The pathway has fewer reactants and interactions than coagulation, but the generation of a complete quantitative model is complicated by the need to work at the solid‐liquid interface of fibrin. Diagnostic tools to detect disease states due to malfunctions in the fibrinolysis pathway are also not so well developed as is the case with coagulation. However, there are clearly a number of inherited or acquired pathologies where hyperfibrinolysis is a serious, potentially life‐threatening problem and a number of antifibrinolytc drugs are available to treat hyperfibrinolysis. These topics will be covered in the following review.

[Early viscoelasticity-based coagulation therapy for severely injured bleeding patients: Report of the consensus group on the consensus conference 2014 for formulation of S2k guidelines]

Although there is increasing interest in the use of a viscoelastic test procedure (ROTEM/TEG) for diagnostics and therapy guidance of severely injured and bleeding patients, currently no uniformly accepted guidelines exist for how this technology should be integrated into clinical treatment. In September 2014 an international multidisciplinary group of opinion leaders in the field of trauma-induced coagulopathy and other disciplines involved in the treatment of severely injured patients were assembled for a 2-day consensus conference in Philadelphia (USA). This panel included trauma/accident surgeons, general/abdominal surgeons, vascular surgeons, emergency/intensive care surgeons, hematologists, transfusion specialists, anesthesiologists, laboratory physicians, pathobiologists/pathophysiologists and the lay public. A total of nine questions regarding the impact of viscoelastic testing in the early treatment of trauma patients were developed prior to the conference by a panel consensus. Early use was defined as baseline viscoelastic test result thresholds obtained within the first minutes of hospital arrival, when conventional laboratory results are not yet available. The available data for each question were then reviewed in person using standardized presentations by the expert panel. A consensus summary document was then developed and reviewed by the panel in an open forum. Finally, a 2-round Delphi poll was administered to the panel of experts regarding viscoelastic thresholds for triggering the initiation of specific treatments including fibrinogen (concentrates), platelet concentrates, blood plasma products and prothrombin complex concentrates (PCC). This report summarizes the findings and recommendations of this consensus conference, which correspond to a S2k guideline according to the system of the Association of the Scientific Medical Societies in Germany (AWMF) and taking formal consensus findings including Delphi methods into consideration.

An in vitro study of the effects of t-PA and tranexamic acid on whole blood coagulation and fibrinolysis

AIMS

Acute traumatic coagulopathy is characterised by fibrinolysis and low fibrinogen. It is unclear how much fibrinogenolysis contributes to reduce fibrinogen levels. The study aim was to: investigate in vitro the effects of tissue-plasminogen activator (t-PA) and tranexamic acid (TXA) on coagulation and fibrinolysis.

METHODS

Whole blood was spiked with varying t-PA concentrations. Clauss fibrinogen levels and thrombelastography (TEG, Haemonetics) were performed, including functional fibrinogen level (FLEV). TXA effects were assessed using four TXA concentrations. Recorded parameters from kaolin activated TEG included maximal amplitude (MA), clot strength (G), percentage lysis (LY). Plasmin-antiplasmin complex (PAP), endogenous thrombin potential (ETP), prothrombin fragment 1+2 (PF1+2), factor V and factor VIII levels were all measured.

RESULTS

t-PA induced fibrinolysis: it increased PAP and LY, but decreased MA and G. t-PA induced fibrinogenolysis, with a concentration-dependant decrease in fibrinogen from 2.7 (2.6-3.1) to 0.8 (0.8-0.9) g/L with 60 nM t-PA. FLEV and fibrinogen levels were well correlated. High t-PA doses increased PF1+2, decreased ETP of 19% and FVIII of 63% but not FV. TXA had no effect on plasmin generation as evidenced by no change in PAP. It corrected LY, MA and G and partly protected fibrinogen against fibrinogenolysis: 0.03 mg/mL TXA reduced the fibrinogen fall induced by t-PA 20 nM from 43% to 14%. TXA halved the FVIII fall and increased ETP.

CONCLUSIONS

t-PA induced plasminogen activation and fibrinogenolysis in a concentration-dependant manner. TXA did not affect plasmin activation but reduced fibrinogenolysis. These results suggest that TXA given early in bleeding patients may prevent fibrinogenolysis.

Blockade of Extracellular High-Mobility Group Box 1 Attenuates Systemic Inflammation and Coagulation Abnormalities in Rats with Acute Traumatic Coagulopathy

BACKGROUND As an extracellularly released mediator, high-mobility group box 1 (HMGB1) initiates sterile inflammation following severe trauma. Serum HMGB1 levels correlate well with acute traumatic coagulopathy (ATC) in trauma patients, which is independently associated with higher mortality. We investigated the involvement of HMGB1 in ATC through blocking extracellular HMGB1. MATERIAL AND METHODS The ATC model was induced by polytrauma and hemorrhage in male Sprague-Dawley rats, which were randomly assigned to sham, ATC, and ATCH (ATC with HMGB1 blockade) groups. Thrombelastography (TEG) was performed to monitor changes in coagulation function. Serum levels of HMGB1, TNF-α, and IL-6 were measured, as well as lung levels of HMGB1 and nuclear factor (NF)-κB and expression of receptor for advanced glycation end-products (RAGE). RESULTS Compared with the sham group, HMGB1 increased the serum levels of TNF-α and IL-6, whereas HMGB1 blockade inhibited the induction of TNF-α and IL-6. HMGB1 also induced elevated serum soluble P-selectin and fibrinolysis markers plasmin-antiplasmin complex, which both were reduced by HMGB1 blockade. Thrombelastography revealed the hypocoagulability status in the ATC group, which was attenuated by anti-HMGB1 antibody. Furthermore, the lung level of NF-κB and expression of RAGE were decreased by anti-HMGB1 antibody, suggesting the role of RAGE/NF-κB pathway in ATC. CONCLUSIONS HMGB1 blockade can attenuate inflammation and coagulopathy in ATC rats. Anti-HMGB1 antibody might exert protective effects partly through the RAGE/NF-κB pathway. Thus, HMGB1 has potential as a therapeutic target in ATC.

Shock-induced systemic hyperfibrinolysis is attenuated by plasma-first resuscitation

BACKGROUND

We developed a hemorrhagic shock animal model to replicate an urban prehospital setting where resuscitation fluids are limited to assess the effect of saline versus plasma in coagulopathic patients. An in vitro model of whole blood dilution with saline exacerbated tissue plasminogen activator (tPA)-mediated fibrinolysis, while plasma dilution did not change fibrinolysis. We hypothesize that shock-induced hyperfibrinolysis can be attenuated by resuscitation with plasma while exacerbated by saline.

METHODS

Sprague-Dawley rats were hemorrhaged to a mean arterial pressure of 25 mm Hg and maintained in shock for 30 minutes. Animals were resuscitated with either normal saline (NS) or platelet-free plasma (PFP) with a 10% total blood volume bolus, followed by an additional 5 minutes of resuscitation with NS to increase blood pressure to a mean arterial pressure of 30 mm Hg. Animals were observed for 15 minutes for the assessment of hemodynamic response and survival. Blood samples were analyzed with thrombelastography paired with protein analysis.

RESULTS

The median percentage of total blood volume shed per group were similar (NS, 52.5% vs. PFP, 55.7; p = 0.065). Survival was 50% in NS compared with 100% in PFP. The change in LY30 and tPA levels from baseline to shock was similar between groups (LY30 PFP, 10; interquartile range [IQR], 4.3-11.2; NS, 4.5; IQR, 4.1-14.2; p = 1.00; tPA PFP, 16.6 ng/mL; IQR, 13.7-27.8; NS, 22.4; IQR, 20.1-25.5; p = 0.240). After resuscitation, the median change in LY30 was greater in the NS group (13.5; IQR, 3.5-19.9) compared with PFP (-4.9%; IQR, -9.22 to 0.25 p = 0.004), but tPA levels did not significantly change (NS, 1.4; IQR, -6.2 to 7.1 vs. PFP, 1.7; IQR, -5.2 to 6.8; p = 0.699).

CONCLUSION

Systemic hyperfibrinolysis is driven by hypoperfusion and associated with increased levels of tPA. Plasma is a superior resuscitation fluid to NS in a prehospital model of severe hemorrhagic shock as it attenuates hyperfibrinolysis and improves systemic perfusion.

The "Death Diamond": Rapid thrombelastography identifies lethal hyperfibrinolysis

BACKGROUND

Postinjury hyperfibrinolysis (HF), defined as LY30 of 3% or greater on rapid thrombelastography (rTEG), is associated with high mortality and large use of blood products. We observed that some cases of HF are reversible and are associated with patients who respond to hemostatic resuscitation; however, other cases of severe HF seem to be associated with these patients' inevitable demise. We therefore sought to define this unsurvivable subtype of HF as a recognizable rTEG tracing pattern.

METHODS

We queried our trauma registry for patients who either died or spent at least 1 day in the intensive care unit, received at least 1 U of packed red blood cells, and had an admission rTEG. Within this group of 572 patients, we identified 42 pairs of nonsurvivors and survivors who matched on age, sex, injury mechanism, and New Injury Severity Score (NISS). We inspected the rTEG tracings to ascertain if any pattern was found exclusively within the nonsurviving group and applied these findings to the cohort of 572 patients to assess the predictive value for mortality.

RESULTS

Within the matched group, 17% of the patients developed HF. Within the HF subgroup, a unique rTEG pattern was present in 14 HF patients who died and in none of the survivors. This pattern was a "diamond-shaped" tracing with a short time to maximum amplitude of 14 minutes or shorter and complete lysis before the LY30 point. When these criteria are applied to the 572 unmatched patients, this pattern had a 100% positive predictive value for mortality.

CONCLUSION

Patients displaying the "death diamond" pattern on their admission rTEG are at higher risk for mortality. Given the volume of blood products and other resources that these patients consume, this thrombelastography pattern may represent an objective criterion to discontinue efforts at hemostatic resuscitation.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Tranexamic Acid Use in United States Trauma Centers: A National Survey

Tranexamic acid (TXA) is an antifibrinolytic agent that is listed as an essential medication by the World Health Organization for traumatic hemorrhage. We determined United States–based surgeons’ familiarity with TXA and their use of TXA. An online survey was sent to the 1291 attending surgeon members of a national trauma organization. The survey was organized into three general parts: respondent demographics, perceptions of TXA, and experience with TXA. The survey was completed by 35 per cent of members. TXA was available at 89.1 per cent of centers. Experience with TXA was variable: 38.0 per cent use regularly, 24.9 per cent use it 1 to 2 times per year, 12.3 per cent use it rarely, and 24.7 per cent had never used it. Among surgeons who had used TXA, 77.1 per cent noted that TXA had reduced bleeding, but 22.9 per cent indicated that it had not. Reasons for not routinely using TXA included uncertain clinical benefit (47.7%) and unfamiliarity (31.5%). Finally, 90.5 per cent of respondents indicated that are looking toward national organizations to develop practice guidelines. TXA is widely available in civilian United States trauma centers. Although a majority of surveyed surgeons had used TXA, only 38 per cent use TXA regularly for significant traumatic hemorrhage; principal reasons for this are uncertainty regarding clinical benefit and unfamiliarity with the drug. National guidelines are sought.

Bleeding complications during cardiac electronic device implantation in patients receiving antithrombotic therapy: is there any value of local tranexamic acid?

Background

The perioperative use of antithrombotic therapy is associated with increased bleeding risk after cardiac implantable electronic device (CIED) implantation. Topical application of tranexamic acid (TXA) is effective in reducing bleeding complications after various surgical operations. However, there is no information regarding local TXA application during CIED procedures. The purpose of our study was to evaluate bleeding complications rates during CIED implantation with and without topical TXA use in patients receiving antithrombotic treatment.

Methods

We conducted a retrospective analysis of consecutive patients undergoing CIED implantation while receiving warfarin or dual antiplatelet (DAPT) or warfarin plus DAPT treatment. Study population was classified in two groups according to presence or absence of topical TXA use during CIED implantation. Pocket hematoma (PH), major bleeding complications (MBC) and thromboembolic events occuring within 90 days were compared.

Results

A total of 135 consecutive patients were identified and included in the analysis. The mean age was 60 ± 11 years old. Topical TXA application during implantation was reported in 52 patients (TXA group). The remaining 83 patients were assigned to the control group. PH occurred in 7.7 % patients in the TXA group and 26.5 % patients in the control group (P = 0.013). The MBC was reported in 5.8 % patients in the TXA and 20.5 % patients in control group (P = 0.024). Univariate logistic regression analysis identified age, history of recent stent implantation, periprocedural spironolactone use, periprocedural warfarin use, perioperative warfarin plus DAPT use, cardiac resynchronization therapy, and topical TXA application during CIED implantation as predicting factors of PH. Multivariate analysis showed that perioperative warfarin plus DAPT use (OR = 10.874, 95 % CI: 2.496–47.365, P = 0.001) and topical TXA application during CIED procedure (OR = 0.059, 95 % CI: 0.012–0.300, P = 0.001) were independent predictors of PH. Perioperative warfarin plus DAPT use and topical TXA application were also found to be independent predictors of MBC in multivariate analyses. No thromboembolic complications was recorded in the study group.

Conclusion

The present study demonstrated that the topical TXA application during CIED implantation is associated with reduced PH and MBC in patients with high bleeding risk.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0251-1) contains supplementary material, which is available to authorized users.

Overwhelming tPA release, not PAI-1 degradation, is responsible for hyperfibrinolysis in severely injured trauma patients

BACKGROUND

Trauma-induced coagulopathy (TIC) is associated with a fourfold increased risk of mortality. Hyperfibrinolysis is a component of TIC, but its mechanism is poorly understood. Plasminogen activation inhibitor (PAI-1) degradation by activated protein C has been proposed as a mechanism for deregulation of the plasmin system in hemorrhagic shock, but in other settings of ischemia, tissue plasminogen activator (tPA) has been shown to be elevated. We hypothesized that the hyperfibrinolysis in TIC is not the result of PAI-1 degradation but is driven by an increase in tPA, with resultant loss of PAI-1 activity through complexation with tPA.

METHODS

Eighty-six consecutive trauma activation patients had blood collected at the earliest time after injury and were screened for hyperfibrinolysis using thrombelastography (TEG). Twenty-five hyperfibrinolytic patients were compared with 14 healthy controls using enzyme-linked immunosorbent assays for active tPA, active PAI-1, and PAI-1/tPA complex. Blood was also subjected to TEG with exogenous tPA challenge as a functional assay for PAI-1 reserve.

RESULTS

Total levels of PAI-1 (the sum of the active PAI-1 species and its covalent complex with tPA) are not significantly different between hyperfibrinolytic trauma patients and healthy controls: median, 104 pM (interquartile range [IQR], 48-201 pM) versus 115 pM (IQR, 54-202 pM). The ratio of active to complexed PAI-1, however, was two orders of magnitude lower in hyperfibrinolytic patients than in controls. Conversely, total tPA levels (active + complex) were significantly higher in hyperfibrinolytic patients than in controls: 139 pM (IQR, 68-237 pM) versus 32 pM (IQR, 16-37 pM). Hyperfibrinolytic trauma patients displayed increased sensitivity to exogenous challenge with tPA (median LY30 of 66.8% compared with 9.6% for controls).

CONCLUSION

Depletion of PAI-1 in TIC is driven by an increase in tPA, not PAI-1 degradation. The tPA-challenged TEG, based on this principle, is a functional test for PAI-1 reserves. Exploration of the mechanism of up-regulation of tPA is critical to an understanding of hyperfibrinolysis in trauma.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level II.

Monitoring of hematological and hemostatic parameters in neurocritical care patients

Anemia and bleeding are paramount concerns in neurocritical care and often relate to the severity of intracranial hemorrhage. Anemia is generally associated with worse outcomes, and efforts to minimize anemia through reduced volume of blood sampled are encouraged. Point-of-care-testing reliably detects the use of non-steroidal anti-inflammatory drugs that may worsen bleeding and reduce platelet activity, particularly in patients with intracerebral hemorrhage. How best to monitor the effect of platelet transfusion or platelet-activating therapy is not well studied. For patients known to take novel oral anticoagulants, drug-specific coagulation tests before neurosurgical intervention are prudent.

Viscoelastic measurements of platelet function, not fibrinogen function, predicts sensitivity to tissue-type plasminogen activator in trauma patients

BACKGROUND

Systemic hyperfibrinolysis is a lethal phenotype of trauma-induced coagulopathy. Its pathogenesis is poorly understood. Recent studies have support a central role of platelets in hemostasis and in fibrinolysis regulation, implying that platelet impairment is integral to the development of postinjury systemic hyperfibrinolysis.

OBJECTIVE

The objective of this study was to identify if platelet function is associated with blood clot sensitivity to fibrinolysis. We hypothesize that platelet impairment of the ADP pathway correlates with fibrinolysis sensitivity in trauma patients.

METHODS

A prospective observational study of patients meeting the criteria for the highest level of activation at an urban trauma center was performed. Viscoelastic parameters associated with platelet function (maximum amplitude [MA]) were measured with native thrombelastography (TEG), and TEG platelet mapping of the ADP pathway (ADP-MA). The contribution of fibrinogen to clotting was measured with TEG (angle) and the TEG functional fibrinogen (FF) assay (FF-MA). Another TEG assay containing tissue-type plasminogen activator (t-PA) (75 ng mL(-1) ) was used to assess clot sensitivity to an exogenous fibrinolytic stimulus by use of the TEG lysis at 30 min (LY30) variable. Multivariate linear regression was used to identify which TEG variable correlated with t-PA-LY30 (quantification of fibrinolysis sensitivity).

RESULTS

Fifty-eight trauma patients were included in the analysis, with a median injury severity score of 17 and a base deficit of 6 mEq L(-1) . TEG parameters that significantly predicted t-PA-LY30 were related to platelet function (ADP-MA, P = 0.001; MA, P < 0.001) but not to fibrinogen (FF-MA, P = 0.773; angle, P = 0.083). Clinical predictors of platelet ADP impairment included calcium level (P = 0.001), base deficit (P = 0.001), and injury severity (P = 0.001).

RESULTS AND CONCLUSIONS

Platelet impairment of the ADP pathway is associated with increased sensitivity to t-PA. ADP pathway inhibition in platelets may be an early step in the pathogenesis of systemic hyperfibrinolysis.

2014 Consensus conference on viscoelastic test-based transfusion guidelines for early trauma resuscitation: Report of the panel

There has been an increased interest in the use of viscoelastic testing to guide blood product replacement during the acute resuscitation of the injured patient. Currently, no uniformly accepted guidelines exist for how this technology should be integrated into clinical care. In September 2014, an international multidisciplinary group of leaders in the field of trauma coagulopathy and resuscitation was assembled for a 2-day consensus conference in Philadelphia, Pennsylvania. This panel included trauma surgeons, hematologists, blood bank specialists, anesthesiologists, and the lay public.Nine questions regarding the impact of viscoelastic testing in the early resuscitation of trauma patients were developed before the conference by panel consensus. Early use was defined as baseline viscoelastic test result thresholds obtained within the first minutes of hospital arrival-when conventional laboratory results are not available. The available data for each question were then reviewed in person using standardized presentations by the expert panel. A consensus summary document was then developed and reviewed by the panel in an open forum. Finally, a two-round Delphi poll was administered to the panel of experts regarding viscoelastic thresholds for triggering the initiation of specific treatments including fibrinogen, platelets, plasma, and prothrombin complex concentrates. This report summarizes the findings and recommendations of this consensus conference.

Viscoelastic Methods of Blood Clotting Assessment - A Multidisciplinary Review

Viscoelastic methods (VEM) made available the bedside assessment of blood clotting. Unlike standard laboratory tests, the results are based on the whole blood coagulation and are available in real time at a much faster turnaround time. In combination with our new knowledge about pathophysiology of the trauma-induced coagulopathy, the goal-oriented treatment protocols have been recently proposed for the initial management of bleeding in trauma victims. Additionally, the utility of viscoelastic monitoring devices has been proved even outside this setting in cardiosurgical patients or those undergoing liver transplantation. Many other situations were described in literature showing the potential use of bedside analysis of coagulation for the management of bleeding or critically ill patients. In the near future, we may expect further improvement in current bedside diagnostic tools enabling not only the assessment of secondary hemostasis but also the platelet aggregation. More sensitive assays for new anticoagulants are underway. Aim of this review is to offer the reader a multidisciplinary overview of VEM and their potential use in anesthesiology and critical care.

Admission fibrinogen levels in severe trauma patients: A comparison of elderly and younger patients

INTRODUCTION

Acute coagulopathy of trauma has been much discussed recently. However, the changes in coagulation markers after trauma in the elderly are unknown. Furthermore, the baseline fibrinogen level is high in elderly patients, and the question remains as to whether fibrinogen levels also decrease early and the degree of decrease in elderly trauma patients. The purpose of this study was to compare coagulation markers including the fibrinogen level on admission in younger and elderly severe trauma patients.

METHODS

A cohort of severe trauma patients (Injury Severity Score (ISS) ≥16), admitted from January 2011 to June 2014, with coagulation markers including the fibrinogen level on admission available, was reviewed retrospectively. The patients were divided into a younger (16-64 years old) and an older (≥65 years old) group based upon their age at presentation. Activated partial thromboplastin time (aPTT), international normalized ratio (INR), fibrinogen, and D-dimer were compared between the younger and older groups.

RESULTS

There were 251 patients who met the inclusion criteria for this analysis. The younger group included 117 patients and the older group included 134 patients. The median aPTT (26.3 vs 27.5s, P=0.001) and median D-dimer levels (18.8 vs 40.2 μg/dL, P=0.006) were significantly higher in the older group. However, the fibrinogen level (205 vs 248 mg/dL, P<0.001) was significantly higher in the older group. The regression lines of fibrinogen and age in non-massive transfusion and massive transfusion cases are given by Y=1.03 X+185 (r=0.24, r(2)=0.06, P<0.001) and Y=0.86 X+134 (r=0.25, r(2)=0.06, P=0.09) respectively, and the fibrinogen levels tended to increase with older age in severe trauma patients.

CONCLUSIONS

The fibrinogen level did not show a low value as it can in younger patients in elderly patients. Therefore, the fibrinogen level is difficult to use as an early indicator of acute blood loss with haemorrhage in elderly severe trauma patients, as it can be used in younger patients. Thus, it is necessary to keep in mind that the fibrinogen level increases by approximately 1mg/dL when the age increases by 1 year and to carefully observe the fibrinogen level even if the admission level is not low.

Endogenous Fibrinolysis: An Important Mediator of Thrombus Formation and Cardiovascular Risk

Most acute cardiovascular events are attributable to arterial thrombosis. Plaque rupture or erosion stimulates platelet activation, aggregation, and thrombosis, whilst simultaneously activating enzymatic processes that mediate endogenous fibrinolysis to physiologically maintain vessel patency. Interplay between these pathways determines clinical outcome. If proaggregatory factors predominate, the thrombus may propagate, leading to vessel occlusion. However, if balanced by a healthy fibrinolytic system, thrombosis may not occur or cause lasting occlusion. Despite abundant evidence for the fibrinolytic system regulating thrombosis, it has been overlooked compared with platelet reactivity, partly due to a lack of techniques to measure it. We evaluate evidence for endogenous fibrinolysis in arterial thrombosis and review techniques to assess it, including biomarkers and global assays, such as thromboelastography and the Global Thrombosis Test. Global assays, simultaneously assessing proaggregatory and fibrinolytic pathways, could play a role in risk stratification and in identifying impaired fibrinolysis as a potential target for pharmacological modulation.

TACTIC: Trans-Agency Consortium for Trauma-Induced Coagulopathy

Trauma-induced coagulopathy (TIC) includes heterogeneous coagulopathic syndromes with different underlying causes, and treatment is challenged by limited diagnostic tests to discriminate between these entities in the acute setting. We provide an overview of progress in understanding the mechanisms of TIC and the context for several of the hypotheses that will be tested in 'TACTIC'. Although connected to ongoing clinical trials in trauma, TACTIC itself has no intent to conduct clinical trials. We do anticipate that 'early translation' of promising results will occur. Functions anticipated at this early translational level include: (i) basic science groundwork for future therapeutic candidates; (ii) development of acute coagulopathy scoring systems; (iii) coagulation factor composition-based computational analysis; (iv) characterization of novel analytes including tissue factor, polyphosphates, histones, meizothrombin and α-thrombin-antithrombin complexes, factor XIa, platelet and endothelial markers of activation, signatures of protein C activation and fibrinolysis markers; and (v) assessment of viscoelastic tests and new point-of-care methods.

The impact of tranexamic acid on mortality in injured patients with hyperfibrinolysis

BACKGROUND

In 2011, supported by data from two separate trauma centers, we implemented a protocol to administer tranexamic acid (TXA) in trauma patients with evidence of hyperfibrinolysis (HF) on admission. The purpose of this study was to examine whether the use of TXA in patients with HF determined by admission rapid thrombelastography was associated with improved survival.

METHODS

Following institutional review board approval, we evaluated all trauma patients 16 years or older admitted between September 2009 and September 2013. HF was defined as LY-30 of 3% or greater. Patients with LY-30 less than 3.0% were excluded. Patients were divided into those who received TXA (TXA group) and those who did not (no-TXA group). After univariate analyses, a purposeful, logistic regression model was developed a priori to evaluate the impact of TXA on mortality (controlling for age, sex, Injury Severity Score (ISS), arrival physiology, and base deficit).

RESULTS

A total of 1,032 patients met study criteria. Ninety-eight (10%) received TXA, and 934 (90%) did not. TXA patients were older (median age, 37 years vs. 32 years), were more severely injured (median ISS, 29 vs. 14), had a lower blood pressure (median systolic blood pressure 103 mm Hg vs. 125 mm Hg), and were more likely to be in shock (median, base excess, -5 mmol/dL vs. -2 mmol/dL), all p < 0.05. Twenty-three percent of the patients had a repeat thrombelastography within 6 hours; 8.8% of the TXA patients had LY-30 of 3% or greater on repeat rapid thrombelastography (vs. 10.1% in the no-TXA group, p = 0.679). Unadjusted in-hospital mortality was higher in the TXA group (40% vs. 17%, p < 0.001). There were no differences in venous thromboembolism (3.3% vs. 3.8%). Logistic regression failed to find a difference in in-hospital mortality among those receiving TXA (odds ratio, 0.74; 95% confidence interval, 0.38-1.40; p 0.80).

CONCLUSION

In the current study, the use of TXA was not associated with a reduction in mortality. Further studies are needed to better define who will benefit from an administration of TXA.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Discovery and safety profiling of a potent preclinical candidate, (4-[4-[[(3R)-3-(hydroxycarbamoyl)-8-azaspiro[4.5]decan-3-yl]sulfonyl]phenoxy]-N-methylbenzamide) (CM-352), for the prevention and treatment of hemorrhage

Discovery of potent and safe therapeutics that improve upon currently available antifibrinolytics, e.g., tranexamic acid (TXA, 1) and aprotinin, has been challenging. Matrix metalloproteinases (MMPs) participate in thrombus dissolution. Then we designed a novel series of optimized MMP inhibitors that went through phenotypic screening consisting of thromboelastometry and mouse tail bleeding. Our optimized lead compound, CM-352 (2), inhibited fibrinolysis in human whole blood functional assays and was more effective than the current standard of care, 1, in the tail-bleeding model using a 30 000 times lower dose. Moreover, 2 reduced blood loss during liver hepatectomy, while 1 and aprotinin had no effect. Molecule 2 displayed optimal pharmacokinetic and safety profiles with no evidence of thrombosis or coagulation impairment. This novel mechanism of action, targeting MMP, defines a new class of antihemorrhagic agents without interfering with normal hemostatic function. Furthermore, 2 represents a preclinical candidate for the acute treatment of bleeding.

Plasma is the physiologic buffer of tissue plasminogen activator-mediated fibrinolysis: rationale for plasma-first resuscitation after life-threatening hemorrhage

BACKGROUND

Prehospital resuscitation with crystalloid exacerbates fibrinolysis, which is associated with high mortality. We hypothesized that plasma compared with crystalloid resuscitation prevents hyperfibrinolysis in a tissue plasminogen activator (tPA)-rich environment via preservation of proteins essential for regulation of fibrinolysis.

STUDY DESIGN

Healthy individuals donated blood, which was assayed using a native (nonactivated) thrombelastography (TEG). Whole-blood was mixed with normal saline (NS) or platelet poor plasma (PPP) at progressive dilutions. Tissue plasminogen activator was added to promote a fibrinolytic environment. In a separate experiment, PPP was run through a 100 kDa filter and liquid remaining on top of the filter (TFP) and below the filter (BFP) was obtained. Whole blood was diluted by 50% with TFP, BFP, and NS and assayed with a tPA TEG challenge. The TFP and BFP were assayed for protein concentration and protein composition.

RESULTS

Normal saline and PPP dilution of whole blood without tPA did not affect clot lysis at 30 minutes (LY30) (NS Spearman's rho 0.300, p = 0.186 and PPP 0.294, p = 0.288). When tPA was added, NS dilution of whole blood increased LY30 in a percentage-dependent manner (0.844, p < 0.001), but did not significantly increase with PPP dilution (0.270, p = 0.202). The difference in LY30 from whole blood to diluted whole blood with PPP (mean change, -1.05, 95% CI, -9.42 to 7.33) was similar with TFP (1.23, 95% CI, -5.20 to 7.66, p = 0.992). However, both BFP (37.65, 95% CI 24.47 to 50.82, p = 0.001) and NS (47.36, 95% CI 34.3 to 60.45, p < 0.001) showed large increases in fibrinolysis compared with PPP.

CONCLUSIONS

Crystalloid and plasma dilution of whole blood does not increase fibrinolysis. However, NS dilution of whole blood increases susceptibility to tPA-mediated fibrinolysis. Plasma resuscitation, simulated by plasma dilution of whole blood, attenuates increased susceptibility to tPA-mediated fibrinolysis. The benefits of plasma resuscitation are mediated through preservation of plasma proteins.

Impact of β-adrenoceptor blockade on systemic inflammation and coagulation disturbances in rats with acute traumatic coagulopathy

BACKGROUND

Sympathetic hyperactivity occurs early in acute traumatic coagulopathy (ATC) and is closely related to its development. β-adrenoceptor antagonists are known to alleviate adverse sympathetic effects and improve outcome in various diseases. We investigated whether β-blockers have protective effects against inflammation and endothelial and hemostatic disorders in ATC.

MATERIAL AND METHODS

ATC was induced in male Sprague-Dawley rats by trauma and hemorrhagic shock. Rats were randomly assigned to the sham, ATCC (ATC control), and ATCB (ATC with beta-adrenoceptor blockade) groups. Rats were injected intraperitoneally with propranolol or vehicle at baseline. Heart rate variability (HRV) and markers of inflammation, coagulation, and endothelial activation were measured, and Western blotting analysis of nuclear factor (NF)-κB was done after shock. Separate ATCC and ATCB groups were observed to compare overall mortality.

RESULTS

HRV showed enhanced sympathetic tone in the ATCC group, which was reversed by propranolol. Propranolol attenuated the induction of pro-inflammatory cytokines TNF-α and IL-6, as well as fibrinolysis markers plasmin antiplasmin complex and tissue-type plasminogen activator. The increased serum syndecan-1 and soluble thrombomodulin were inhibited by propranolol, and the NF-κB expression was also decreased by propranolol pretreatment. But propranolol did not alter overall mortality in rats with ATC after shock.

CONCLUSIONS

Beta-adrenoceptor blockade can alleviate sympathetic hyperactivity and exert anti-inflammatory, anti-fibrinolysis, and endothelial protective effects, confirming its pivotal role in the pathogenesis of ATC. Its mechanism in ATC should be explored further.

Hyperfibrinolysis, physiologic fibrinolysis, and fibrinolysis shutdown: the spectrum of postinjury fibrinolysis and relevance to antifibrinolytic therapy

BACKGROUND

Fibrinolysis is a physiologic process maintaining patency of the microvasculature. Maladaptive overactivation of this essential function (hyperfibrinolysis) is proposed as a pathologic mechanism of trauma-induced coagulopathy. Conversely, the shutdown of fibrinolysis has also been observed as a pathologic phenomenon. We hypothesize that there is a level of fibrinolysis between these two extremes that have a survival benefit for the severely injured patients.

METHODS

Thrombelastography and clinical data were prospectively collected on trauma patients admitted to our Level I trauma center from 2010 to 2013. Patients with an Injury Severity Score (ISS) of 15 or greater were evaluated. The percentage of fibrinolysis at 30 minutes by thrombelastography was used to stratify three groups as follows: hyperfibrinolysis (≥3%), physiologic (0.081-2.9%), and shutdown (0-0.08%). The threshold for hyperfibrinolysis was based on existing literature. The remaining groups were established on a cutoff of 0.8%, determined by the highest point of specificity and sensitivity for mortality on a receiver operating characteristic curve.

RESULTS

One hundred eighty patients were included in the study. The median age was 42 years (interquartile range [IQR], 28-55 years), 70% were male, and 21% had penetrating injuries. The median ISS was 29 (IQR, 22-36), and the median base deficit was 9 mEq/L (IQR, 6-13 mEq/L). Distribution of fibrinolysis was as follows: shutdown, 64% (115 of 180); physiologic, 18% (32 of 180); and hyperfibrinolysis, 18% (33 of 180). Mortality rates were lower for the physiologic group (3%) compared with the hyperfibrinolysis (44%) and shutdown (17%) groups (p = 0.001).

CONCLUSION

We have identified a U-shaped distribution of death related to the fibrinolysis system in response to major trauma, with a nadir in mortality, with level of fibrinolysis after 30 minutes between 0.81% and 2.9%. Exogenous inhibition of the fibrinolysis system in severely injured patients requires careful selection, as it may have an adverse affect on survival.

LEVEL OF EVIDENCE

Prognostic study, level III.

The pathogenesis of traumatic coagulopathy

Over the last 10 years, the management of major haemorrhage in trauma patients has changed radically. This is mainly due to the recognition that many patients who are bleeding when they come in to the emergency department have an established coagulopathy before the haemodilution effects of fluid resuscitation. This has led to the use of new terminology: acute traumatic coagulopathy, acute coagulopathy of trauma shock or trauma-induced coagulopathy. The recognition of acute traumatic coagulopathy is important, because we now understand that its presence is a prognostic indicator, as it is associated with poor clinical outcome. This has driven a change in clinical management, so that the previous approach of maintaining an adequate circulating volume and oxygen carrying capacity before, as a secondary event, dealing with coagulopathy, has changed to haemostatic resuscitation as early as possible. While there is as yet no universally accepted assay or definition, many experts use prolongation of the prothrombin time to indicate that there is, indeed, a coagulopathy. Hypoxia, acidosis and hypothermia and hormonal, immunological and cytokine production, alongside consumption and blood loss, and the dilutional effects of resuscitation may occur to varying extents depending on the type of tissue damaged, the type and extent of injury, predisposing to, or amplifying, activation of coagulation, platelets, fibrinolysis. These are discussed in detail within the article.

Design of the Study of Tranexamic Acid during Air Medical Prehospital Transport (STAAMP) Trial: Addressing the Knowledge Gaps

Abstract Hemorrhage and coagulopathy remain major drivers of early preventable mortality in military and civilian trauma. The development of trauma-induced coagulopathy and hyperfibrinolysis is associated with poor outcomes. Interest in the use of tranexamic acid (TXA) in hemorrhaging patients as an antifibrinolytic agent has grown recently. Additionally, several reports describe immunomodulatory effects of TXA that may confer benefit independent of its antifibrinolytic actions. A large trial demonstrated a mortality benefit for early TXA administration in patients at risk for hemorrhage; however, questions remain about the applicability in developed trauma systems and the mechanism by which TXA reduces mortality. We describe here the rationale, design, and challenges of the Study of Tranexamic Acid during Air Medical Prehospital transport (STAAMP) trial. The primary objective is to determine the effect of prehospital TXA infusion during air medical transport on 30-day mortality in patients at risk of traumatic hemorrhage. This study is a multicenter, placebo-controlled, double-blind, randomized clinical trial. The trial will enroll trauma patients with hypotension and tachycardia from 4 level I trauma center air medical transport programs. It includes a 2-phase intervention, with a prehospital and in-hospital phase to investigate multiple dosing regimens. The trial will also explore the effects of TXA on the coagulation and inflammatory response following injury. The trial will be conducted under exception for informed consent for emergency research and thus required an investigational new drug approval from the U.S. Food and Drug Administration as well as a community consultation process. It was designed to address several existing knowledge gaps and research priorities regarding TXA use in trauma.

Viscoelastic guidance of resuscitation

PURPOSE OF REVIEW

Bleeding in trauma carries a high mortality and is increased in case of coagulopathy. Our understanding of hemostasis and coagulopathy has improved, leading to a change in the protocols for hemostatic monitoring. This review describes the current state of evidence supporting the use of viscoelastic hemostatic assays to guide trauma resuscitation.

RECENT FINDINGS

Viscoelastic hemostatic assays such as thrombelastography and rotational thrombelastometry have shown to reduce bleeding, transfusion of fresh frozen plasma and platelets, and possibly mortality in different surgical populations. In trauma care, viscoelastic hemostatic assays allows for rapid and timely identification of coagulopathy and individualized, goal-directed transfusion therapy. As part of the resuscitation concept, viscoelastic hemostatic assays seem to improve outcome also in trauma; however, there is a need for randomized clinical trials to confirm this.

SUMMARY

We are moving toward avoiding coagulopathy by individualized, goal-directed transfusion therapy, using viscoelastic hemostatic assays to guide ongoing resuscitation of actively bleeding patients in a goal-directed manner.

Thrombelastographic pattern recognition in renal disease and trauma

BACKGROUND

Thrombelastography (TEG) is a viscoelastic hemostatic assay. We have observed that end-stage renal disease (ESRD) and trauma-induced coagulopathy (TIC) produce distinctive TEG tracings. We hypothesized that rigorously definable TEG patterns could discriminate between healthy controls and patients with ESRD and TIC.

METHODS

TEG was performed on blood from ESRD patients (n = 54) and blood from trauma patients requiring a massive blood transfusion (n = 16). Plots of independent TEG parameters were analyzed for patterns coupled to disease state, compared with controls. Decision trees for taxonomic classification were then built using the "R-Project" statistical software.

RESULTS

Minimally overlapping clusters of TEG results were observed for the three patient groups when coordinate pairs of maximum amplitude (MA) and TEG-activated clotting time (ACT) were plotted on orthogonal axes. Based on these groupings, a taxonomical classification tree was constructed using MA and TEG ACT. Branch points were set at an ACT of 103 s, and these branches subdivided for MA at 60.8 mm for the high ACT branch and 72.6 mm for the low ACT branch, providing a correct classification rate of 93.4%.

CONCLUSIONS

ESRD and TIC demonstrate distinct TEG patterns. The coagulopathy of ESRD is typified by a prolonged enzymatic phase of clot formation, with normal-to-elevated final clot strength. Conversely, TIC is typified by prolonged clot formation and weakened clot strength. Our taxonomic categorization constitutes a rigorous system for the algorithmic interpretation of TEG based on cluster analysis. This will form the basis for clinical decision support software for viscoelastic hemostatic assays.

An update on the coagulopathy of trauma

Trauma remains the leading cause of death with bleeding as the primary cause of preventable mortality during the first 24 h following trauma. When death occurs, it happens quickly, typically within the first 6 h after injury. One of four patients to arrive in the emergency department after trauma is already in the state of acute traumatic coagulopathy and shock. The principal drivers of acute traumatic coagulopathy have been characterized by tissue hypoperfusion, inflammation, and the acute activation of the neurohumoral system. Hypoperfusion leads to an activation of protein C with cleavage of activated factors V and VIII and the inhibition of plasminogen activator inhibitor 1 with subsequent hyperfibrinolysis. Endothelial damage and activation result in Weibel-Palade body degradation and glycocalyx shedding associated with autoheparinization. In contrast, there is an iatrogenic coagulopathy that occurs secondary to uncritical volume therapy leading to acidosis, hypothermia, and hemodilution. This coagulopathy then may be an integral part of the "vicious cycle" when combined with acidosis and hypothermia. The present article summarizes an update on the principal mechanisms and triggers of the coagulopathy of trauma including traumatic brain injury.

Strategies for the management of haemorrhage following pelvic fractures and associated trauma-induced coagulopathy

Exsanguination is the second most common cause of death in patients who suffer severe trauma. The management of haemodynamically unstable high-energy pelvic injuries remains controversial, as there are no universally accepted guidelines to direct surgeons on the ideal use of pelvic packing or early angio-embolisation. Additionally, the optimal resuscitation strategy, which prevents or halts the progression of the trauma-induced coagulopathy, remains unknown. Although early and aggressive use of blood products in these patients appears to improve survival, over-enthusiastic resuscitative measures may not be the safest strategy. This paper provides an overview of the classification of pelvic injuries and the current evidence on best-practice management of high-energy pelvic fractures, including resuscitation, transfusion of blood components, monitoring of coagulopathy, and procedural interventions including pre-peritoneal pelvic packing, external fixation and angiographic embolisation.

Defining Early Trauma-induced Coagulopathy Using Thromboelastography

Early trauma-induced coagulopathy (ETIC) is abnormal coagulation detected on presentation, but a clear description is lacking. We used thromboelastography (TEG) to characterize ETIC. Data were prospectively collected on high-acuity trauma activations at an urban Level I trauma center between July 2012 and May 2013. Patients with admission TEG before any blood transfusion were stratified by Injury Severity Score (ISS): mild (less than 16), moderate (16 to 24), severe (25 or greater). TEG parameters were compared between groups. ETIC was defined as any abnormality detected on TEG. Fifty-two patients were included; mean age was 49 years and mean time to the emergency department was 26 minutes. Mean ISS for the cohort was 17 with 28 patients in mild, eight in moderate, and 16 in severe. Glasgow Coma Score was lower and head Abbreviated Injury Scale was higher in severe ( P < 0.001). Forty-three (83%) patients had an abnormal TEG. Shortened reaction (R) time was noted in 42 patients. There were no differences in any TEG parameters between the injury severity groups. Hyperfibrinolysis was detected in four (8%) patients. ETIC was present in over 80 per cent of high-acuity trauma activations irrespective of injury severity and characterized primarily by shortened R time, indicating ETIC is initially described by a hypercoagulable state as a result of thrombin generation.

Effect of thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) on diagnosis of coagulopathy, transfusion guidance and mortality in trauma: descriptive systematic review

Introduction

The understanding of coagulopathies in trauma has increased interest in thromboelastography (TEG®) and thromboelastometry (ROTEM®), which promptly evaluate the entire clotting process and may guide blood product therapy. Our objective was to review the evidence for their role in diagnosing early coagulopathies, guiding blood transfusion, and reducing mortality in injured patients.

Methods

We considered observational studies and randomized controlled trials (MEDLINE, EMBASE, and Cochrane databases) to February 2014 that examined TEG®/ROTEM® in adult trauma patients. We extracted data on demographics, diagnosis of early coagulopathies, blood transfusion, and mortality. We assessed methodologic quality by using the Newcastle-Ottawa scale (NOS) for observational studies and QUADAS-2 tool for diagnostic accuracy studies.

Results

Fifty-five studies (12,489 patients) met inclusion criteria, including 38 prospective cohort studies, 15 retrospective cohort studies, two before-after studies, and no randomized trials. Methodologic quality was moderate (mean NOS score, 6.07; standard deviation, 0.49). With QUADAS-2, only three of 47 studies (6.4%) had a low risk of bias in all domains (patient selection, index test, reference standard and flow and timing); 37 of 47 studies (78.8%) had low concerns regarding applicability. Studies investigated TEG®/ROTEM® for diagnosis of early coagulopathies (n = 40) or for associations with blood-product transfusion (n = 25) or mortality (n = 24). Most (n = 52) were single-center studies. Techniques examined included rapid TEG® (n =12), ROTEM® (n = 18), TEG® (n = 23), or both TEG® and rapid TEG® (n = 2). Many TEG®/ROTEM® measurements were associated with early coagulopathies, including some (hypercoagulability, hyperfibrinolysis, platelet dysfunction) not assessed by routine screening coagulation tests. Standard measures of diagnostic accuracy were inconsistently reported. Many abnormalities predicted the need for massive transfusion and death, but predictive performance was not consistently superior to routine tests. One observational study suggested that a ROTEM®-based transfusion algorithm reduced blood-product transfusion, but TEG®/ROTEM®-based resuscitation was not associated with lower mortality in most studies.

Conclusions

Limited evidence from observational data suggest that TEG®/ROTEM® tests diagnose early trauma coagulopathy and may predict blood-product transfusion and mortality in trauma. Effects on blood-product transfusion, mortality, and other patient-important outcomes remain unproven in randomized trials.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0518-9) contains supplementary material, which is available to authorized users.

Vagus nerve stimulation improves coagulopathy in hemorrhagic shock: a thromboelastometric animal model study

Introduction

Inflammation plays a major role in the multifactorial process of trauma associated coagulopathy. The vagus nerve regulates the cholinergic anti-inflammatory pathway. We hypothesized that efferent vagus nerve stimulation (VNS) can improve coagulopathy by modulating the inflammatory response to hemorrhage.

Methods

Wistar rats (n = 24) were divided in 3 groups: Group (G1) Sham hemorrhagic shock (HS); (G2) HS w/o VNS; (G3) HS followed by division of the vagus nerves and VNS of the distal stumps. Hemorrhage (45% of baseline MAPx15 minutes) was followed by normotensive resuscitation with LR. Vagus nerves were stimulated (3.5 mA, 5 Hz) for 30 sec 7 times. Samples were obtained at baseline and at 60 minutes for thromboelastometry (Rotem®) and cytokine assays (IL-1 and IL-10). ANOVA was used for statistical analysis; significance was set at p < 0.05.

Results

Maximum clot firmness (MCF) significantly decreased in G2 after HS (71.5 ± 1.5 vs. 64 ± 1.6) (p < 0.05). MCF significantly increased in G3 compared to baseline (67.3 ± 2.7 vs. 71.5 ± 1.2) (p < 0.05). G3 also showed significant improvement in Alfa angle, and Clot Formation Time (CFT) compared to baseline. IL-1 increased significantly in group 2 and decrease in group 3, while IL-10 increased in group 3 (p < 0.05).

Conclusions

Electrical stimulation of efferent vagus nerves, during resuscitation (G3), decreases inflammatory response to hemorrhage and improves coagulation.

Kinetic model facilitates analysis of fibrin generation and its modulation by clotting factors: implications for hemostasis-enhancing therapies

Current mechanistic knowledge of protein interactions driving blood coagulation has come largely from experiments with simple synthetic systems, which only partially represent the molecular composition of human blood plasma. Here, we investigate the ability of the suggested molecular mechanisms to account for fibrin generation and degradation kinetics in diverse, physiologically relevant in vitro systems. We represented the protein interaction network responsible for thrombin generation, fibrin formation, and fibrinolysis as a computational kinetic model and benchmarked it against published and newly generated data reflecting diverse experimental conditions. We then applied the model to investigate the ability of fibrinogen and a recently proposed prothrombin complex concentrate composition, PCC-AT (a combination of the clotting factors II, IX, X, and antithrombin), to restore normal thrombin and fibrin generation in diluted plasma. The kinetic model captured essential features of empirically detected effects of prothrombin, fibrinogen, and thrombin-activatable fibrinolysis inhibitor titrations on fibrin formation and degradation kinetics. Moreover, the model qualitatively predicted the impact of tissue factor and tPA/tenecteplase level variations on the fibrin output. In the majority of considered cases, PCC-AT combined with fibrinogen accurately approximated both normal thrombin and fibrin generation in diluted plasma, which could not be accomplished by fibrinogen or PCC-AT acting alone. We conclude that a common network of protein interactions can account for key kinetic features characterizing fibrin accumulation and degradation in human blood plasma under diverse experimental conditions. Combined PCC-AT/fibrinogen supplementation is a promising strategy to reverse the deleterious effects of dilution-induced coagulopathy associated with traumatic bleeding.