Fibrinolysis greater than 3% is the critical value for initiation of antifibrinolytic therapy

Effect of tranexamic acid administration on acute traumatic coagulopathy in rats with polytrauma and hemorrhage

Trauma and hemorrhagic shock can lead to acute traumatic coagulopathy (ATC) that is not fully reversed by prehospital resuscitation as simulated with a limited volume of fresh whole blood (FWB) in a rat model. Tranexamic Acid (TXA) is used as an anti-fibrinolytic agent to reduce surgical bleeding if administered prior to or during surgery, and to improve survival in trauma if given early after trauma. It is not clear from the existing clinical literature whether TXA has the same mechanism of action in both settings. This study sought to explore the molecular mechanisms of TXA activity in trauma and determine whether administration of TXA as a supplement to FWB resuscitation could attenuate the established ATC in a rat model simulating prehospital resuscitation of polytrauma and hemorrhagic shock. In a parallel in-vitro study, the effects on clotting assays of adding plasmin at varying doses along with either simultaneous addition of TXA or pre-incubation with TXA were measured, and the results suggested that maximum anti-fibrinolytic effect of TXA on plasmin-induced fibrinolysis required pre-incubation of TXA and plasmin prior to clot initiation. In the rat model, ATC was induced by polytrauma followed by 40% hemorrhage. One hour after trauma, the rats were resuscitated with FWB collected from donor rats. Vehicle or TXA (10mg/kg) was given as bolus either before trauma (TXA-BT), or 45min after trauma prior to resuscitation (TXA-AT). The TXA-BT group was included to contrast the coagulation effects of TXA when used as it is in elective surgery vs. what is actually feasible in real trauma patients (TXA-AT group). A single dose of TXA prior to trauma significantly delayed the onset of ATC from 30min to 120min after trauma as measured by a rise in prothrombin time (PT). The plasma d-dimer as well as plasminogen/fibrinogen ratio in traumatized liver of TXA-BT were significantly lower as compared to vehicle and TXA-AT. Wet/dry weight ratio and leukocytes infiltration of lungs were significantly decreased only if TXA was administrated later, prior to resuscitation (TXA-AT). In conclusion: Limited prehospital trauma resuscitation that includes FWB and TXA may not correct established systemic ATC, but rather may improve overall outcomes of resuscitation by attenuation of acute lung injury. By contrast, TXA given prior to trauma reduced levels of fibrinolysis at the site of tissue injury and circulatory d-dimer, and delayed development of coagulopathy independent of reduction of fibrinogen levels following trauma. These findings highlight the importance of early administration of TXA in trauma, and suggest that further optimization of dosing protocols in trauma to exploit TXA’s various sites and modes of action may further improve patient outcomes.

The association of preoperative atrial fibrillation with post-cardiopulmonary bypass hyperfibrinolysis in rheumatic valvular heart disease patients

OBJECTIVE

The purpose of this study was to assess the fibrinolytic status after cardiopulmonary bypass in rheumatic valvular heart disease patients, and detect the associated factors of post-cardiopulmonary bypass hyperfibrinolysis.

METHODS

According to the fibrinolytic status after cardiopulmonary bypass, 203 rheumatic valvular heart disease patients were divided into two groups: hyperfibrinolysis group (H group, n = 78) and non-hyperfibrinolysis group (NH group, n = 125). The demographic characteristics, operative variables, and postoperative follow-ups were compared between these two groups.

RESULTS

The incidence of hyperfibrinolysis was 38.4% after cardiopulmonary bypass. Patients in the H group had a significant higher incidence of preoperative atrial fibrillation than patients in the NH group (92.3% vs. 55.2%, P < 0.01). Furthermore, postoperative daily drainage (655.3 ± 131.5 ml vs. 535.4 ± 161.4 ml, P < 0.01), transfusion volume of fresh frozen plasma (621.8 ± 220.2 ml vs. 455.2 ± 208.5 ml, P < 0.01), and red blood cells (5.9 ± 2.2 u vs. 4.7 ± 2.8 u, P < 0.01) was greater in the H group than in the NH group. Moreover, the logistic regression analysis revealed that preoperative atrial fibrillation was associated with post-cardiopulmonary bypass hyperfibrinolysis (OR = 19.691, 95% CI = 6.849-56.612; P < 0.05).

CONCLUSION

Preoperative artial fibrillation is associated with post-cardiopulmonary bypass hyperfibrinolysis in rheumatic valvular heart disease patients.

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.

Systemic hyperfibrinolysis after trauma: a pilot study of targeted proteomic analysis of superposed mechanisms in patient plasma

BACKGROUND

Viscoelastic measurements of hemostasis indicate that 20% of seriously injured patients exhibit systemic hyperfibrinolysis, with increased early mortality. These patients have normal clot formation with rapid clot lysis. Targeted proteomics was applied to quantify plasma proteins from hyperfibrinolytic (HF) patients to elucidate potential pathophysiology.

METHODS

Blood samples were collected in the field or at emergency department arrival and thrombelastography (TEG) was used to characterize in vitro clot formation under native and tissue plasminogen activator (tPA)-stimulated conditions. Ten samples were taken from injured patients exhibiting normal lysis time at 30 min (Ly30), "eufibrinolytic" (EF), 10 from HF patients, defined as tPA-stimulated TEG Ly30 >50%, and 10 from healthy controls. Trauma patient samples were analyzed by targeted proteomics and ELISA assays for specific coagulation proteins.

RESULTS

HF patients exhibited increased plasminogen activation. Thirty-three proteins from the HF patients were significantly decreased compared with healthy controls and EF patients; 17 were coagulation proteins with anti-protease consumption (p < 0.005). The other 16 decreased proteins indicate activation of the alternate complement pathway, depletion of carrier proteins, and four glycoproteins. CXC7 was elevated in all injured patients versus healthy controls (p < 0.005), and 35 proteins were unchanged across all groups (p > 0.1 and fold change of concentrations of 0.75-1.3).

CONCLUSION

HF patients had significant decreases in specific proteins and support mechanisms known in trauma-induced hyperfibrinolysis and also unexpected decreases in coagulation factors, factors II, X, and XIII, without changes in clot formation (SP, R times, or angle). Decreased clot stability in HF patients was corroborated with tPA-stimulated TEGs.

LEVEL OF EVIDENCE

Prognostic, level III.

Microfluidics contrasted to thrombelastography: perplexities in defining hypercoagulability

BACKGROUND

Elevated clot strength (maximum amplitude [MA]) measured by thrombelastography (TEG) is associated with thrombotic complications. However, it remains unclear how MA translates to thrombotic risks, as this measurement is independent of time, blood flow, and clot degradation. We hypothesize that under flow conditions, increased clot strength correlates to time-dependent measurements of coagulation and resistance to fibrinolysis.

MATERIALS AND METHODS

Surgical patients at high risk of thrombotic complications were analyzed with TEG and total thrombus-formation analysis system (T-TAS). TEG hypercoagulability was defined as an r <10.2 min, angle >59, MA >66 or LY30 <0.2% (based off of healthy control data, n = 141). The T-TAS AR and PL chips were used to measure clotting at arterial shear rates. T-TAS measurements include occlusion start time, occlusion time (OT), occlusion speed (OSp), and total clot generation (area under the curve). These measurements were correlated to TEG indices (R time, angle, MA, and LY30). Both T-TAS and TEG assays were challenged with tissue plasminogen activator (t-PA) to assess clot resistance to fibrinolysis.

RESULTS

Thirty subjects were analyzed, including five controls. TEG-defined hypercoagulability by MA was detected in 52% of the inflammatory bowel disease/cancer patients; 0% was detected in the controls. There were no TEG measurements that significantly correlated with T-TAS AR and PL chip. However, in the presence of t-PA, T-TAS AR determined OSp to have an inverse relationship with TEG angle (-0.477, P = 0.012) and LY30 (-0.449, P = 0.019), and a positive correlation with R time (0.441 P = 0.021). In hypercoagulability determined by TEG MA, T-TAS PL had a significantly reduced OT (4:07 versus 6:27 min, P = 0.043). In hypercoagulability defined by TEG LY30, T-TAS PL had discordant findings, with a significantly prolonged OT (6:36 versus 4:30 min, P = 0.044) and a slower OSp (10.5 versus 19.0 kPa/min, P = 0.030).

CONCLUSIONS

Microfluidic coagulation assessment with T-TAS has an overall poor correlation with most TEG measurements in a predominantly hypercoagulable patient population, except in the presence of t-PA. The one anticipated finding was an elevated MA having a shorter time to platelet-mediated microfluidic occlusion, supporting the role of platelets and hypercoagulability. However, hypercoagulability defined by LY30 had opposing results in which a low LY30 was associated with a longer PL time to occlusion and slower OSp. These discordant findings warrant ongoing investigation into the relationship between clot strength and fibrinolysis under different flow conditions.

Optimizing transfusion strategies in damage control resuscitation: current insights

From clinical and laboratory studies of specific coagulation defects induced by injury, damage control resuscitation (DCR) emerged as the most effective management strategy for hemorrhagic shock. DCR of the trauma patient who has sustained massive blood loss consists of 1) hemorrhage control; 2) permissive hypotension; and 3) the prevention and correction of trauma-induced coagulopathies, referred to collectively here as acute coagulopathy of trauma (ACOT). Trauma patients with ACOT have higher transfusion requirements, may eventually require massive transfusion, and are at higher risk of exsanguinating. Distinct impairments in the hemostatic system associated with trauma include acquired quantitative and qualitative platelet defects, hypocoagulable and hypercoagulable states, and dysregulation of the fibrinolytic system giving rise to hyperfibrinolysis or a phenomenon referred to as fibrinolytic shutdown. Furthermore, ACOT is a component of a systemic host defense dysregulation syndrome that bears several phenotypic features comparable with other acute systemic physiological insults such as sepsis, myocardial infarction, and postcardiac arrest syndrome. Progress in the science of resuscitation has been continuing at an accelerated rate, and clinicians who manage catastrophic blood loss may be incompletely informed of important advances that pertain to DCR. Therefore, we review recent findings that further characterize the pathophysiology of ACOT and describe the application of this new information to optimization of resuscitation strategies for the patient in hemorrhagic shock.

Efficacy of prehospital administration of tranexamic acid in trauma patients: A meta-analysis of the randomized controlled trials

OBJECTIVE

Antifibrinolytic agent tranexamic acid (TXA) has a potential clinical benefit for in-hospital patients with severe bleeding but its effectiveness in pre-hospital settings remains unclear. We conducted a systematic review and meta-analysis to evaluate whether pre-hospital administration of TXA compared to placebo improve patients' outcomes?

METHODS

PubMed, MEDLINE, Cochrane Library, WHO International Clinical Trials Registry Platform, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, clinicaltrials.gov and Google scholar databases were searched for a retrospective, prospective and randomized (RCT) or quasi-RCT studies that assessed the effect of prehospital administration of TXA versus placebo on the outcomes of trauma patients with significant hemorrhage. The main outcomes of interest were 24hour 30-day mortality and in-hospital thromboembolic complications. Two authors independently abstracted the data using a data collection form. Results from different studies were pooled for the analysis, when appropriate.

RESULTS

Out of 92 references identified through the search, two analytical studies met the inclusion criteria. The effect of TXA on 24-hour mortality had a pooled odds ratio (OR) of 0.49 (95% CI 0.28-0.85), 30-day mortality OR of 0.86 (95% CI, 0.56-1.32), and thromboembolic events OR of 0.74 (95% CI, 0.27-2.07).

CONCLUSION

Prehospital TXA appears to reduce early mortality in trauma patients. The pooled analysis also shows a trend toward lower 30-day mortality and reduced risk of thromboembolic events. Additional randomized controlled clinical trials are needed to determine the significance of these trends.

Antifibrinolytic Therapy and Perioperative Considerations

Fibrinolysis is a physiologic component of hemostasis that functions to limit clot formation. However, after trauma or surgery, excessive fibrinolysis may contribute to coagulopathy, bleeding, and inflammatory responses. Antifibrinolytic agents are increasingly used to reduce bleeding, allogeneic blood administration, and adverse clinical outcomes. Tranexamic acid is the agent most extensively studied and used in most countries. This review will explore the role of fibrinolysis as a pathologic mechanism, review the different pharmacologic agents used to inhibit fibrinolysis, and focus on the role of tranexamic acid as a therapeutic agent to reduce bleeding in patients after surgery and trauma.

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.

Tranexamic Acid Use in Prehospital Uncontrolled Hemorrhage

The use of tranexamic acid (TXA) in the treatment of trauma patients was relatively unexplored until the landmark Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage-2 (CRASH-2) trial in 2010 demonstrated a reduction in mortality with the use of TXA. Although this trial was a randomized, double-blinded, placebo-controlled study incorporating >20,000 patients, numerous limitations and weaknesses have been described. As a result, additional studies have followed, delineating the potential risks and benefits of TXA administration. A systematic review of the literature to date reveals a mortality benefit of early (ideally <1 hour and no later than 3 hours after injury) TXA administration in the treatment of severely injured trauma patients (systolic blood pressure <90 mm Hg, heart rate >110). Combined with abundant literature showing a reduction in bleeding in elective surgery, the most significant benefit may be administration of TXA before the patient goes into shock. Those trials that failed to show a mortality benefit of TXA in the treatment of hemorrhagic shock acknowledged that most patients received blood products before TXA administration, thus confounding the results. Although the use of prehospital TXA in the severely injured trauma patient will become more clear with the trauma studies currently underway, the current literature supports the use of prehospital TXA in this high-risk population. We recommend considering a 1 g TXA bolus en route to definitive care in high-risk patients and withholding subsequent doses until hyperfibrinolysis is confirmed by thromboelastography.

The hyperfibrinolytic phenotype is the most lethal and resource intense presentation of fibrinolysis in massive transfusion patients

BACKGROUND

Among bleeding patients, we hypothesized that the hyperfibrinolytic (HF) phenotype would be associated with the highest mortality, whereas shutdown (SD) patients would have the greatest complication burden.

METHODS

Severely injured patients predicted to receive a massive transfusion at 12 Level I trauma centers were randomized to one of two transfusion ratios as described in the Pragmatic, Randomized, Optimal Platelet and Plasma Ratio trial. Fibrinolysis phenotypes were determined based on admission clot lysis at 30 minutes (LY30): SD ≤0.8%, physiologic (PHYS) 0.9-2.9%, and HF ≥3%. Univariate and multivariate analysis was performed. Logistic regression was used to adjust for age, gender, arrival physiology, shock, injury severity, center effect, and treatment arm.

RESULTS

Among the 680 patients randomized, 547(80%) had admission thrombelastography (TEG) values available to determine fibrinolytic phenotypes. Compared to SD and PHYS, HF patients had higher Injury Severity Score (25 vs. 25 vs. 34), greater base deficit (-8 vs. -6 vs. -12) and were more uniformly hypocoagulable on admission by PT, PTT, and TEG values; all p <0.001. HF patients also received more red blood cells, plasma, and platelets (at 3, 6, and 24 hours); had fewer ICU-, ventilator-, and hospital-free days; and had higher 24-hour and 30-day mortality. There were no differences in complications between the three phenotypes. Multivariate logistic regression demonstrated that HF on admission was associated with a threefold higher mortality (OR 3.06, 95% CI 1.57-5.95, p = 0.001).

CONCLUSIONS

Previous data have shown that both the SD and HF phenotypes are associated with increased mortality and complications in the general trauma population. However, in a large cohort of bleeding patients, HF was confirmed to be a much more lethal and resource-intense phenotype. These data suggest that further research into the understanding of SD and HF is warranted to improve outcomes in this patient population.

LEVEL OF EVIDENCE

Prognostic, level II.

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

BACKGROUND

Tranexamic acid (TXA) administration after trauma has not been proven to improve survival in the United States. Trauma patients were presented to the hospital with a spectrum of fibrinolytic activity, in which physiological levels of fibrinolysis are associated with the lowest mortality. We hypothesize that trauma patients who present to the hospital with physiological levels of fibrinolysis will have increased mortality if they receive TXA.

MATERIALS AND METHODS

Severely injured trauma patients, followed prospectively from 2014 to 2016, were included in the analysis. The patient's first thrombelastography was used to stratify patients into fibrinolysis phenotypes which included fibrinolysis shutdown, physiological fibrinolysis, and systemic hyperfibrinolysis. The primary outcome was in-hospital mortality.

RESULTS

A total of 232 patients were analyzed (11% received TXA) with an overall mortality rate of 20%. TXA administration was associated with a higher new injury severity score (49 versus 28; P = 0.001), massive transfusion rate (69% versus 12%; P < 0.001), and mortality (52% versus 17%; P < 0.001). Hyperfibrinolysis and shutdown had higher mortality rates than physiological group (24% versus 30% versus 14%; P = 0.050). The effect of TXA within phenotypes was not significant for shutdown (28% versus 38%; P = 0.604) but was significant in the physiological group (11% versus 63%; P < 0.001) and systemic hyperfibrinolysis (19% versus 55%; P = 0.023). After adjusting for new injury severity score, TXA remained a significant predictor of mortality for patients with physiological fibrinolysis (P = 0.018).

CONCLUSIONS

There was no clear benefit of receiving TXA in this study, and patients who present to the hospital with physiologic levels of fibrinolysis, who received TXA, had the highest mortality. The role of TXA in mature trauma systems remains unclear, and emerging data supports it may have adverse effects.

Antifibrinolytics in a rural trauma state: assessing the opportunities

Background

Tranexamic acid (TXA) has demonstrated improved mortality among trauma patients. However, recent evidence from urban US trauma centers has failed to show a benefit among the civilian population. TXA in rural states has not been evaluated. This study aimed to evaluate the current use of TXA in the rural trauma population.

Methods

A retrospective observational review at a level 1 trauma center based in a rural environment. Records were reviewed for TXA indications. TXA indication was defined as: systolic blood pressure <90 mm Hg, blood transfusion, or with a clinical concern for ongoing bleeding. Patients were ineligible if the time since injury was >3 hours.

Results

400 patients were evaluated. 54% of patients met indications for TXA. 14% of these received TXA. 30.4% with an indication for TXA were ineligible due to arrival beyond 3 hours from time of injury. 135 patients arrived as transfers, 265 from the scene. There was no difference in TXA indications between scene and transfers (73 vs 144, p=1). Transfers were more likely to arrive beyond the 3-hour window (59 vs 7, p=0.001). Mortality for patients treated with TXA was 12.5%. This was not significantly different from patients not treated with TXA (19%).

Discussion

In a rural system, long transfers exclude most patients from treatment with TXA. A multicenter rural trauma center study will be needed to better define the optimal use of TXA in rural populations.

Level of evidence

Level IV data: therapeutic/care management.

Rotational thromboelastometry significantly optimizes transfusion practices for damage control resuscitation in combat casualties

BACKGROUND

Up to 40% of combat casualties with a truncal injury die of massive hemorrhage before reaching a surgeon. This hemorrhage can be prevented with damage control resuscitation (DCR) methods, which are focused on replacing shed whole blood by empirically transfusing blood components in a 1:1:1:1 ratio of platelets:fresh frozen plasma:erythrocytes:cryoprecipitate (PLT:FFP:RBC:CRYO). Measurement of hemostatic function with rotational thromboelastometry (ROTEM) may allow optimization of the type and quantity of blood products transfused. Our hypothesis was that incorporating ROTEM measurements into DCR methods at the US Role 3 hospital at Bagram Airfield, Afghanistan would change the standard transfusion ratios of 1:1:1:1 to a product mix tailored specifically for the combat causality.

METHODS

This retrospective study collected data from the Department of Defense Trauma Registry to compare transfusion practices and outcomes before and after ROTEM deployment to Bagram Airfield. Over the course of six months, 134 trauma patients received a transfusion (pre-ROTEM) and 85 received a transfusion and underwent ROTEM testing (post-ROTEM). Trauma teams received instruction on ROTEM use and interpretation, with no provision of a specific transfusion protocol, to supplement their clinical judgment and practice.

RESULTS

The pre and post groups were not significantly different in terms of mortality, massive transfusion protocol activation, mean injury severity score, or coagulation measurements. Despite the difference in size, each group received an equal total number of transfusions. However, the post-ROTEM group received a significant increase in PLT and CRYO transfusions ratios, 4× and 2×, respectively.

CONCLUSION

The introduction of ROTEM significantly improved adherence to DCR practices. The transfusion differences suggest that aggressive DCR without thromboelastometry data may result in reduced hemostatic support and underestimate the need for PLT and CRYO. Thus, future controlled trials should include ROTEM-guided coagulation management in trauma resuscitation.

LEVEL OF EVIDENCE

Therapeutic, level IV.

Targeted Thromboelastographic (TEG) Blood Component and Pharmacologic Hemostatic Therapy in Traumatic and Acquired Coagulopathy

Trauma-induced coagulopathy (TIC) is a recently described condition which traditionally has been diagnosed by the common coagulation tests (CCTs) such as prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), platelet count, and fibrinogen levels. The varying sensitivity and specificity of these CCTs have led trauma coagulation researchers and clinicians to use Viscoelastic Tests (VET) such as Thromboelastography (TEG) to provide Targeted Thromboelastographic Hemostatic and Adjunctive Therapy (TTHAT) in a goal directed fashion to those trauma patients in need of hemostatic resuscitation. This review describes the utility of VETs, in particular, TEG, to provide TTHAT in trauma and acquired non-trauma-induced coagulopathy.

Decreasing the Use of Damage Control Laparotomy in Trauma: A Quality Improvement Project

BACKGROUND

Our institution has published damage control laparotomy (DCL) rates of 30% and documented the substantial morbidity associated with the open abdomen. The purpose of this quality improvement (QI) project was to decrease the rate of DCL at a busy, Level I trauma center in the US.

STUDY DESIGN

A prospective cohort of all emergent trauma laparotomies from November 2013 to October 2015 (QI group) was followed. The QI intervention was multifaceted and included audit and feedback for every DCL case. Morbidity and mortality of the QI patients were compared with those from a published control (control group: emergent laparotomy from January 2011 to October 2013).

RESULTS

A significant decrease was observed immediately on beginning the QI project, from a 39% DCL rate in the control period to 23% in the QI group (p < 0.001). This decrease was sustained over the 2-year study period. There were no differences in demographics, Injury Severity Score, or transfusions between the groups. No differences organ/space infection (control 16% vs QI 12%; p = 0.15), fascial dehiscence (6% vs 8%; p = 0.20), unplanned relaparotomy (11% vs 10%; p = 0.58), or mortality (9% vs 10%; p = 0.69) were observed. The reduction in use resulted in a decrease of 68 DCLs over the 2-year period. There was a further reduction in the rate of DCL to 17% after completion of the QI project.

CONCLUSIONS

A QI initiative rapidly changed the use of DCL and improved quality of care by decreasing resource use without an increase morbidity or mortality. This decrease was sustained during the QI period and further improved upon after its completion.

Rapid thrombelastography thresholds for goal-directed resuscitation of patients at risk for massive transfusion

BACKGROUND

Uncontrolled hemorrhage is a leading cause of mortality after trauma accounting for up to 40% of deaths. Massive transfusion protocols offer a proven benefit in resuscitation of these patients. Recently, the superiority of thrombelastography (TEG)-guided resuscitation over strategies guided by conventional clotting assays has been established. We seek to determine optimal thresholds for rapid (r)-TEG driven resuscitation.

METHODS

The r-TEG data were reviewed for 190 patients presenting to our level 1 trauma center from 2010 to 2015. Criteria for inclusion were highest level trauma activation in patients 18 years or older with hypotension presumed due to acute blood loss. Exclusion criteria included isolated gunshot wound to the head, pregnancy, and chronic liver disease. Receiver operating characteristic (ROC) analysis was performed to test the predictive performance of r-TEG for massive transfusion requirement defined by need for (1) >10 units of RBCs total or death in the first 6 hours or (2) >4 units of RBCs in any hour within the first 6 hours. Cutpoint analysis was then performed to determine optimal thresholds for TEG-based resuscitation.

RESULTS

The ROC analysis of r-TEG yielded areas under the curve (AUC) greater than 70% for all outputs with respect to both transfusion thresholds considered, with exception of activated clotting time and lysis at 30 minutes for greater than 4 U RBC in any hour in the first 6 hours. Optimal cutpoint analysis of the resultant ROC curves was performed and for each value, the most sensitive cutpoint was identified, respectively activated clotting time of 128 seconds or longer, angle (α) of 65 degrees or less, maximum amplitude of 55 mm or less, and lysis at 30 minutes of 5% or greater.

CONCLUSIONS

Through ROC analysis of prospective TEG data, we have identified optimal thresholds to guide hemostatic resuscitation. These thresholds should be validated in a prospective multicenter trial.

LEVEL OF EVIDENCE

Therapeutic study, level V.

Abnormalities in fibrinolysis at the time of admission are associated with deep vein thrombosis, mortality, and disability in a pediatric trauma population

BACKGROUND

Abnormalities in fibrinolysis are common and associated with increased mortality in injured adults. While hyperfibrinolysis (HF) and fibrinolysis shutdown (SD) are potential prognostic indicators and treatment targets in adults, these derangements are not well described in a pediatric trauma cohort.

METHODS

This was a prospective analysis of highest level trauma activations in subjects aged 0 to 18 years presenting to our academic center between June 1, 2015, and July 31, 2016, with admission rapid thrombelastograph. Shutdown was defined as LY30 (lysis 30 minutes after the maximum amplitude has been reached) of 0.8% or less and HF defined as LY30 of 3.0% or greater. Variables of interest included demographics, admission vital signs and laboratory values, injuries, incidence of venous thromboembolism under our screening protocol, death, and functional disability (discharge to facility or dependence in functional independence measure category). Youden index determined optimal definition of SD, then Wilcoxon rank-sum, Kruskal-Wallis, and Fisher exact tests were performed.

RESULTS

One hundred thirty-three patients are included with median age of 10 years (interquartile range [IQR], 5-13 years); male sex, 5.4%; median Injury Severity Score, 17 (IQR, 10-26); blunt mechanism, 68.4%. Youden analysis defined SD as LY30 of 0.8 or less. In total, 38.3% (n = 51) had SD on admission; 19.6% (n = 26) had HF, and 42.1% (n = 56) were normal. Mortality rate was 9.0% (n = 12), and deep vein thrombosis incidence was 10.7% (n = 13/121 surviving). Shutdown and HF were both associated with mortality (p = 0.014 and p = 0.021) and blood transfusion (p = 0.001 and p < 0.001); SD was also associated with disability (p < 0.001) and deep vein thrombosis (p = 0.002). Blunt mechanism was associated with SD, and penetrating mechanism was associated with HF (p = 0.011). Both SD (p = 0.001) and HF (p = 0.036) were associated with elevated international normalized ratio. LY30 did not differ significantly across age groups.

CONCLUSIONS

Children demonstrate high rates of inhibition (SD) and overactivation (HF) of fibrinolysis after injury. Shutdown and HF are both associated with poor outcomes. Shutdown is a particularly poor prognostic indicator, accounting for the greatest percentage of death, disability, and patients requiring transfusion, as well as later development of hypercoagulable state. The addition of thrombelastograph to pediatric trauma care protocols should be considered as it contributes important prognostic and clinical information.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III.

Tissue injury suppresses fibrinolysis after hemorrhagic shock in nonhuman primates (rhesus macaque)

BACKGROUND

Hypoperfusion is associated with hyperfibrinolysis and early death from exsanguination, whereas tissue trauma is associated with hypofibrinolysis and delayed death from organ failure. We sought to elucidate the effects of injury patterns on fibrinolysis phenotypes using a nonhuman primate (NHP) model.

METHODS

NHPs were randomized to three injury groups (n = 8/group): 60 minutes severe pressure-targeted controlled hemorrhagic shock (HS); HS + soft tissue injury (HS+); or HS + soft tissue injury + femur fracture (HS++). Animals were resuscitated and monitored for 360 minutes. Blood samples were collected at baseline, end-of-shock, end-of-resuscitation (EOR), and T = 360 minutes for assessments of: severity of shock (lactate) and coagulation via prothrombin time, partial thromboplastin time, D-dimer, fibrinogen, antithrombin-III, von Willebrand factor, and viscoelastic testing (ROTEM). Results are reported as mean ± SEM; statistics: two-way analysis of variance and t-tests (significance: p < 0.05).

RESULTS

Blood loss, prothrombin time, partial thromboplastin time, antithrombin-III, fibrinogen, and von Willebrand factor were equivalent among groups and viscoelastic testing revealed few differences throughout the study. D-dimer increased approximately threefold, at EOR in the HS group, and at T = 360 minutes in the HS+ and HS++ groups (p < 0.05). At EOR, in the HS group compared with the HS+ and HS++ groups; the D-dimer-lactate ratio was twofold greater (2.2 ± 0.3 vs. 1.1 ± 0.3 and 1.1 ± 0.2, respectively; p < 0.05) and tissue factor-activated fibrin clot 30-minute lysis index was lower (98 ± 1% vs. 100 ± 0% and 100 ± 0%, respectively; p < 0.05).

CONCLUSION

NHPs in HS exhibit acute suppression of fibrinolysis in the presence of tissue injury. Additional assessments to more comprehensively evaluate the mechanisms linking tissue injury with the observed fibrinolysis shutdown response are warranted.

Targeted Coagulation Management in Severe Trauma: The Controversies and the Evidence

Hemorrhage in the setting of severe trauma is a leading cause of death worldwide. The pathophysiology of hemorrhage and coagulopathy in severe trauma is complex and remains poorly understood. Most clinicians currently treating trauma patients acknowledge the presence of a coagulopathy unique to trauma patients-trauma-induced coagulopathy (TIC)-independently associated with increased mortality. The complexity and incomplete understanding of TIC has resulted in significant controversy regarding optimum management. Although the majority of trauma centers utilize fixed-ratio massive transfusion protocols in severe traumatic hemorrhage, a widely accepted "ideal" transfusion ratio of blood to blood products remains elusive. The recent use of viscoelastic hemostatic assays (VHAs) to guide blood product replacement has further provoked debate as to the optimum transfusion strategy. The use of VHA to quantify the functional contributions of individual components of the coagulation system may permit targeted treatment of TIC but remains controversial and is unlikely to demonstrate a mortality benefit in light of the heterogeneity of the trauma population. Thus, VHA-guided algorithms as an alternative to fixed product ratios in trauma are not universally accepted, and a hybrid strategy starting with fixed-ratio transfusion and incorporating VHA data as they become available is favored by some institutions. We review the current evidence for the management of coagulopathy in trauma, the rationale behind the use of targeted and fixed-ratio approaches and explore future directions.

Hemoglobin-based oxygen carriers promote systemic hyperfibrinolysis that is both dependent and independent of plasmin

BACKGROUND

Hyperfibrinolysis plays an integral role in the genesis of trauma-induced coagulopathy. Recent data demonstrate that red blood cell lysis promotes fibrinolysis; however, the mechanism is unclear. Hemoglobin-based oxygen carriers (HBOCs) have been developed for resuscitation and have been associated with coagulopathy. We hypothesize that replacement of whole blood (WB) using an HBOC results in a coagulopathy because of the presence of free hemoglobin.

MATERIALS AND METHODS

WB was sampled from healthy donors (n = 6). The clotting profile of each citrated sample was evaluated using native thromboelastography. Serial titrations were performed using both HBOC (PolyHeme) and normal saline (NS; 5%, 25%, and 50%) and evaluated both with and without a 75-ng/mL tissue plasminogen activator (tPA) challenge. Tranexamic acid (TXA) was added to inhibit plasmin-dependent fibrinolysis. Fibrinolysis was measured and recorded as lysis at 30 min (LY30), the percentage of clot LY30 after maximal clot strength. Dilution of WB with NS or HBOC was correlated using LY30 via Spearman rho coefficients. Groups were also compared using a Friedman test and post hoc analysis with a Bonferroni adjustment.

RESULTS

tPA-provoked fibrinolysis was enhanced by both HBOC (median LY30 at 5%, 25%, and 50% titrations: 11%, 21%, and 44%, respectively; Spearman = 0.94; P < 0.001) and NS (11%, 28%, and 58%, respectively; Spearman = 0.790; P < 0.001). However, HBOC also enhanced fibrinolysis without the addition of tPA (1%, 4%, 5%; Spearman = 0.735; P = 0.001) and NS did not (1%, 2%, 1%; r = 0.300; P = 0.186. Moreover, addition of TXA did not alter or inhibit this fibrinolysis (WB versus 50% HBOC: 1.8% versus 5.7%, P = 0.04). There was no significant difference in fibrinolysis of HBOC with or without TXA (50% HBOC versus 50% HBOC + TXA: 5.6% versus 5.7%, P = 0.92). In addition, the increased fibrinolysis seen with NS was reversed when TXA was present (WB versus 50% NS: 1.8% versus 1.7%, P = 1.0).

CONCLUSIONS

HBOCs enhance fibrinolysis both with and without addition of tPA; moreover, this mechanism is independent of plasmin as the phenomenon persists in the presence of TXA. Our findings indicate the hemoglobin molecule or its components stimulate fibrinolysis by both tPA-dependent and innate mechanisms.

Haemotherapy algorithm for the management of trauma-induced coagulopathy: an Australian perspective

PURPOSE OF REVIEW

Recent advances in the understanding of the pathophysiological processes associated with traumatic haemorrhage and trauma-induced coagulopathy have resulted in improved outcomes for seriously injured trauma patients. However, a significant number of trauma patients still die from haemorrhage. This article reviews the various transfusion strategies utilized in the management of traumatic haemorrhage and describes the major haemorrhage protocol (MHP) strategy employed by an Australian trauma centre.

RECENT FINDINGS

Few topics in trauma resuscitation incite as much debate and controversy as to what constitutes the 'ideal' MHP. There is a widespread geographical and institutional variation in clinical practice. Three strategies are commonly utilized; fixed ratio major haemorrhage protocol (FRMHP), viscoelastic haemostatic assay (VHA)-guided MHP and hybrid MHP. The majority of trauma centres utilize an FRMHP and there is high-level evidence to support the use of high blood product ratios. It can be argued that the FRMHP is too simplistic to be applied to all trauma patients and that the use of VHA-guided MHP with predominant factor concentrate transfusion can allow rapid individualized interventions. In between these two strategies is a hybrid MHP, combining early FRMHP with subsequent VHA-guided transfusion.

SUMMARY

There are advantages and disadvantages to each of the various MHP strategies and the evidence base to support one above another with any certainty is lacking at this time. One strategy cannot be considered superior to the other and the choice of MHP is dependent on interpretation of the current literature and local institutional logistical considerations. A number of exciting studies are currently underway that will certainly increase the evidence base and help inform clinical practice.

Goal-directed Hemostatic Resuscitation of Trauma-induced Coagulopathy: A Pragmatic Randomized Clinical Trial Comparing a Viscoelastic Assay to Conventional Coagulation Assays

BACKGROUND

Massive transfusion protocols (MTPs) have become standard of care in the management of bleeding injured patients, yet strategies to guide them vary widely. We conducted a pragmatic, randomized clinical trial (RCT) to test the hypothesis that an MTP goal directed by the viscoelastic assay thrombelastography (TEG) improves survival compared with an MTP guided by conventional coagulation assays (CCA).

METHODS

This RCT enrolled injured patients from an academic level-1 trauma center meeting criteria for MTP activation. Upon MTP activation, patients were randomized to be managed either by an MTP goal directed by TEG or by CCA (ie, international normalized ratio, fibrinogen, platelet count). Primary outcome was 28-day survival.

RESULTS

One hundred eleven patients were included in an intent-to-treat analysis (TEG = 56, CCA = 55). Survival in the TEG group was significantly higher than the CCA group (log-rank P = 0.032, Wilcoxon P = 0.027); 20 deaths in the CCA group (36.4%) compared with 11 in the TEG group (19.6%) (P = 0.049). Most deaths occurred within the first 6 hours from arrival (21.8% CCA group vs 7.1% TEG group) (P = 0.032). CCA patients required similar number of red blood cell units as the TEG patients [CCA: 5.0 (2-11), TEG: 4.5 (2-8)] (P = 0.317), but more plasma units [CCA: 2.0 (0-4), TEG: 0.0 (0-3)] (P = 0.022), and more platelets units [CCA: 0.0 (0-1), TEG: 0.0 (0-0)] (P = 0.041) in the first 2 hours of resuscitation.

CONCLUSIONS

Utilization of a goal-directed, TEG-guided MTP to resuscitate severely injured patients improves survival compared with an MTP guided by CCA and utilizes less plasma and platelet transfusions during the early phase of resuscitation.

Tranexamic acid for treatment and prophylaxis of bleeding and hyperfibrinolysis

Uncontrolled massive bleeding with subsequent derangement of the coagulation system is a major challenge in the management of both surgical and seriously injured patients. Under physiological conditions activators and inhibitors of coagulation regulate the sensitive balance between clot formation and fibrinolysis. In some cases, excessive and diffuse bleeding is caused by systemic activation of fibrinolysis, i. e. hyperfibrinolysis (HF). Uncontrolled HF is associated with a high mortality. Polytrauma patients and those undergoing surgical procedures involving organs rich in plasminogen proactivators (e. g. liver, kidney, pancreas, uterus and prostate gland) are at a high risk for HF. Antifibrinolytics, such as tranexamic acid (TXA) are used for prophylaxis and treatment of bleeding caused by a local or generalized HF as well as other hemorrhagic conditions. TXA is a synthetic lysine analogue that has been available in Austria since 1966. TXA is of utmost importance in the prevention and treatment of traumatic and perioperative bleeding due to the resulting reduction in perioperative blood loss and blood transfusion requirements. The following article presents the different fields of application of TXA with particular respect to indications and dosages, based on a literature search and on current guidelines.

Management of Trauma-Induced Coagulopathy with Thrombelastography

Viscoelastic assays, such as thrombelastography (TEG) and rotational thrombelastometry (ROTEM), have emerged as point-of-care tools that can guide the hemostatic resuscitation of bleeding injured patients. This article describes the role of TEG in contemporary trauma care by explaining this assay's methodology, clinical applications, and result interpretation through description of supporting studies to provide the reader with an evidence-based user's guide. Although TEG and ROTEM are assays based on the same viscoelastic principle, this article is focused on data supporting the use of TEG in trauma, because it is available in trauma centers in North America; ROTEM is mostly available in Europe.

Coagulopathy of Trauma

Coagulopathy is common after injury and develops independently from iatrogenic, hypothermic, and dilutional causes. Despite considerable research on the topic over the past decade, trauma-induced coagulopathy (TIC) continues to portend poor outcomes, including decreased survival. We review the current evidence regarding the diagnosis and mechanisms underlying trauma induced coagulopathy and summarize the debates regarding optimal management strategy including product resuscitation, potential pharmacologic adjuncts, and targeted approaches to hemostasis. Throughout, we will identify areas of continued investigation and controversy in the understanding and management of TIC.

Viscoelastic hemostatic assays in the management of the pediatric trauma patient

Viscoelastic hemostatic assays (VHA), such as TEG and ROTEM, are whole blood tests that depict functional coagulation both numerically and graphically. The development of rapid VHA technology, which allows for the first data points to result within minutes of test initiation, has increased the utility of these tests in the treatment of trauma patients. Both adult and pediatric centers have integrated VHAs into trauma resuscitation and transfusion protocols. Literature regarding the use of VHAs for injured children is limited. Here, we discuss the mechanics and interpretation of VHAs as well as the use of VHAs in data-driven resuscitation of pediatric trauma patients. Novel research on fibrinolysis states after injury as well as hypercoagulable state diagnosed with VHAs are presented.

Persistent Fibrinolysis Shutdown Is Associated with Increased Mortality in Severely Injured Trauma Patients

BACKGROUND

Acute fibrinolysis shutdown is associated with early mortality after trauma; however, no previous studies have investigated the incidence of persistent fibrinolysis or its association with mortality. We tested the hypothesis that persistent fibrinolysis shutdown is associated with mortality in critically ill trauma patients.

STUDY DESIGN

Thromboelastography was performed on ICU admission in 181 adult trauma patients and at 1 week in a subset of 78 patients. Fibrinolysis shutdown was defined as LY30 ≤ 0.8% and was considered transient if resolved by 1 week postinjury or persistent if not. Logistic regression adjusted for age, sex, hemodynamics, and Injury Severity Score (ISS).

RESULTS

Median age was 52 years, 88% were male, and median ISS was 27, with 56% transient fibrinolysis shutdown, 44% persistent fibrinolysis shutdown and 12% mortality. Median LY30 was 0.23% (interquartile range [IQR] 0% to 1.20%) at admission and 0.10% (IQR 0% to 2.05%) at 1 week. Transient shutdown more often occurred after head injury (p = 0.019); persistent shutdown was more often associated with penetrating injury (29% vs 9%; p = 0.020), lower LY30 at ICU admission (0.10% vs 1.15%; p < 0.0001) and at 1 week (0% vs 1.68%; p < 0.0001), and higher mortality (21% vs 5%; p = 0.036). Persistent fibrinolysis shutdown was associated with admission LY30 (odds ratio [OR] 0.05; 95% CI 0.01 to 0.34; p = 0.002) and transfusion of packed RBCs (OR 0.81; 95% CI 0.68 to 0.97; p = 0.021) and platelets (OR 2.81; 95% CI 1.16 to 6.84; p = 0.022); moreover, it was an independent predictor of mortality (OR 8.48; 95% CI 1.35 to 53.18; p = 0.022).

CONCLUSIONS

Persistent fibrinolysis shutdown is associated with late mortality after trauma. A high index of suspicion should be maintained, especially in patients with penetrating injury, reduced LY30 on admission, and/or receiving blood product transfusion. Judicious use of tranexamic acid is advised in this cohort.

Heterogeneous phase fibrinolysis rates by damped oscillation rheometry

BACKGROUND

Devices gauging viscoelastic properties of blood during coagulation like the thromboelastograph support fundamental research as well as point of care needs. Associated fibrinolysis data are based on endogenous species or plasminogen activator added to a homogeneous sample prior to clot formation. Digestion in a monolithic structure differs from the physical situation of thrombolytic therapy where surface reactions dominate.

OBJECTIVE

This study aims to develop rheological testing for heterogeneous phase fibrinolysis.

METHOD

Fibrinolysis rates were determined by phase change of a solid clot induced by autologous plasma/streptokinase (SK) in a rheometer sensitive to viscous damping.

RESULTS

Initial slope or overall change in the logarithmic damping factor indicated fibrinolytic rates. Rates depended on clot geometry, phase volumes, clot composition and SK concentration.

CONCLUSION

The damped oscillation rheometer can be adapted to determine relative rates of heterogeneous fibrinolysis in vitro.

[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.

[Rotational thromboelastometry for the diagnosis of coagulation disorders]

BACKGROUND

Compared to conventional coagulation assays, as prothrombin time (PT) or activated partial thromboplastin time (aPTT), viscoelastic methods of coagulation analysis, including rotational thromboelastometry (ROTEM®, Tem International GmbH, Munich, Germany), yield prognostic benefits. Results of ROTEM® in citrated whole blood could be generated within 10-12 min and allow for a qualitative and semiquantitative characterisation of clot kinetics. Based on ROTEM® results, the switch between empiric approaches of treating coagulopathy to a goal-directed approach could be accelerated. Introduction of ROTEM® reduces transfusion requirements and the need for single factor concentrates. Thus, ROTEM® reduces transfusion-related adverse events, and additionally implement therapeutic cost effectiveness.

OBJECTIVES

This review provides a short introduction in the methodology of ROTEM®, showing how the combination of assays with different commercially available ROTEM® reagents allows for rapid differential diagnosis of common coagulopathies in clinical practice. Furthermore, prognostic benefits and limitations of ROTEM® diagnostics are described. Finally, we discuss the potential fields of ROTEM® application in different surgical settings.

CONCLUSION

ROTEM® appears to be a contemporary, applicable and effective method in diagnosing coagulopathy and for subsequent algorithm-based goal-directed therapy.

Post-translational oxidative modification of fibrinogen is associated with coagulopathy after traumatic injury

Victims of trauma often develop impaired blood clot formation (coagulopathy) that contributes to bleeding and mortality. Fibrin polymerization is one critical component of clot formation that can be impacted by post-translational oxidative modifications of fibrinogen after exposure to oxidants. In vitro evidence suggests that Aα-C domain methionine sulfoxide formation, in particular, can induce conformational changes that prevent lateral aggregation of fibrin protofibrils during polymerization. We used mass spectrometry of plasma from trauma patients to find that fibrinogen Aα-C domain methionine sulfoxide content was selectively-increased in patients with coagulopathy vs. those without coagulopathy. This evidence supports a novel linkage between oxidative stress, coagulopathy, and bleeding after injury.

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.

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.

Acute Fibrinolysis Shutdown after Injury Occurs Frequently and Increases Mortality: A Multicenter Evaluation of 2,540 Severely Injured Patients

BACKGROUND

Fibrinolysis is a physiologic process that maintains microvascular patency by breaking down excessive fibrin clot. Hyperfibrinolysis is associated with a doubling of mortality. Fibrinolysis shutdown, an acute impairment of fibrinolysis, has been recognized as a risk factor for increased mortality. The purpose of this study was to assess the incidence and outcomes of fibrinolysis phenotypes in 2 urban trauma centers.

STUDY DESIGN

Injured patients included in the analysis were admitted between 2010 and 2013, were 18 years of age or older, and had an Injury Severity Score (ISS) > 15. Admission fibrinolysis phenotypes were determined by the clot lysis at 30 minutes (LY30): shutdown ≤ 0.8%, physiologic 0.9% to 2.9%, and hyperfibrinolysis ≥ 3%. Logistic regression was used to adjust for age, arrival blood pressure, ISS, mechanism, and facility.

RESULTS

There were 2,540 patients who met inclusion criteria. Median age was 39 years (interquartile range [IQR] 26 to 55 years) and median ISS was 25 (IQR 20 to 33), with a mortality rate of 21%. Fibrinolysis shutdown was the most common phenotype (46%) followed by physiologic (36%) and hyperfibrinolysis (18%). Hyperfibrinolysis was associated with the highest death rate (34%), followed by shutdown (22%), and physiologic (14%, p < 0.001). The risk of mortality remained increased for hyperfibrinolysis (odds ratio [OR] 3.3, 95% CI 2.4 to 4.6, p < 0.0001) and shutdown (OR 1.6, 95% CI 1.3 to 2.1, p = 0.0003) compared with physiologic when adjusting for age, ISS, mechanism, head injury, and blood pressure (area under the receiver operating characteristics curve 0.82, 95% CI 0.80 to 0.84).

CONCLUSIONS

Fibrinolysis shutdown is the most common phenotype on admission and is associated with increased mortality. These data provide additional evidence of distinct phenotypes of coagulation impairment and that individualized hemostatic therapy may be required.