Pathogenesis of acute traumatic coagulopathy

An in vitro analysis of the effect of acidosis on coagulation in chronic disease states - a thromboelastograph study

Thrombosis is a complication of many chronic illnesses. Chronic obstructive pulmonary disease (COPD) and diabetes mellitus are common medical conditions frequently associated with a hypercoagulable state. Acidaemia has been shown to reduce coagulation. COPD and diabetes mellitus during acute deterioration can present with a severe acidaemia. The impact of this acidaemia on coagulation is poorly studied. Patients presenting with a diagnosis of diabetic ketoacidosis or type II respiratory failure from COPD and a pH of less than 7.2 were included in our study. A coagulation screen and a thromboelastograph (TEG) were performed on admission and 24 hours later. The mean pH on admission was 7.07 and mean base excess was -16.3. The activated partial thromboplastin time was associated with pH change but remained within the normal range (26-41 s). All other coagulation and TEG parameters failed to show evidence of association (p>0.05). In the two models of non-haemorrhagic acidosis investigated, coagulation was not altered by the changes in pH. More work is needed to understand the complex relationship between factors affecting coagulation in individual disease processes.

Damage control resuscitation: lessons learned

BACKGROUND

Damage control resuscitation describes an approach to the early care of very seriously injured patients. The aim is to keep the patient alive whilst avoiding interventions and situations that risk worsening their situation by driving the lethal triad of hypothermia, coagulopathy and acidosis or excessively stimulating the immune-inflammatory system. It is critical that the concepts and practicalities of this approach are understood by all those involved in the early management of trauma patients. This review aims to summarise this and discusses current knowledge on the subject.

INTERVENTIONS

Damage control resuscitation forms part of an overall approach to patient care rather than a specific intervention and has evolved from damage control surgery. It is characterised by early blood product administration, haemorrhage arrest and restoration of blood volume aiming to rapidly restore physiologic stability. The infusion of large volumes of crystalloid is no longer appropriate, instead the aim is to replace lost blood and avoid dilution and coagulopathy. In specific situations, permissive hypotension may also be of benefit, particularly in patients with severe haemorrhage from an arterial source. As rapid arrest of haemorrhage is so important, team-based protocols that deliver patients rapidly but safely, via CT scan where appropriate, to operating theatres or interventional radiology suites form a critical part of this process.

CONCLUSIONS

Given that interventions are so time dependent in the severely injured, it is likely that by further improving trauma systems and protocols, improvements in outcome can still be made. Further research work in this area will allow us to target these approaches more accurately to those patients who can benefit most.

Experimental blunt chest trauma--cardiorespiratory effects of different mechanical ventilation strategies with high positive end-expiratory pressure: a randomized controlled study

Background

Uncertainty persists regarding the optimal ventilatory strategy in trauma patients developing acute respiratory distress syndrome (ARDS). This work aims to assess the effects of two mechanical ventilation strategies with high positive end-expiratory pressure (PEEP) in experimental ARDS following blunt chest trauma.

Methods

Twenty-six juvenile pigs were anesthetized, tracheotomized and mechanically ventilated. A contusion was applied to the right chest using a bolt-shot device. Ninety minutes after contusion, animals were randomized to two different ventilation modes, applied for 24 h: Twelve pigs received conventional pressure-controlled ventilation with moderately low tidal volumes (V_T, 8 ml/kg) and empirically chosen high external PEEP (16cmH₂O) and are referred to as the HP-CMV-group. The other group (n = 14) underwent high-frequency inverse-ratio pressure-controlled ventilation (HFPPV) involving respiratory rate of 65breaths · min⁻¹, inspiratory-to-expiratory-ratio 2:1, development of intrinsic PEEP and recruitment maneuvers, compatible with the rationale of the Open Lung Concept. Hemodynamics, gas exchange and respiratory mechanics were monitored during 24 h. Computed tomography and histology were analyzed in subgroups.

Results

Comparing changes which occurred from randomization (90 min after chest trauma) over the 24-h treatment period, groups differed statistically significantly (all P values for group effect <0.001, General Linear Model analysis) for the following parameters (values are mean ± SD for randomization vs. 24-h): PaO₂ (100 % O₂) (HFPPV 186 ± 82 vs. 450 ± 59 mmHg; HP-CMV 249 ± 73 vs. 243 ± 81 mmHg), venous admixture (HFPPV 34 ± 9.8 vs. 11.2 ± 3.7 %; HP-CMV 33.9 ± 10.5 vs. 21.8 ± 7.2 %), PaCO₂ (HFPPV 46.9 ± 6.8 vs. 33.1 ± 2.4 mmHg; HP-CMV 46.3 ± 11.9 vs. 59.7 ± 18.3 mmHg) and normally aerated lung mass (HFPPV 42.8 ± 11.8 vs. 74.6 ± 10.0 %; HP-CMV 40.7 ± 8.6 vs. 53.4 ± 11.6 %). Improvements occurring after recruitment in the HFPPV-group persisted throughout the study. Peak airway pressure and V_T did not differ significantly. HFPPV animals had lower atelectasis and inflammation scores in gravity-dependent lung areas.

Conclusions

In this model of ARDS following unilateral blunt chest trauma, HFPPV ventilation improved respiratory function and fulfilled relevant ventilation endpoints for trauma patients, i.e. restoration of oxygenation and lung aeration while avoiding hypercapnia and respiratory acidosis.

Does saline resuscitation affect mechanisms of coagulopathy in critically ill trauma patients? An exploratory analysis

Metabolic acidosis has been implicated in the development of coagulopathy, although the specific mechanisms have not been well characterized. We sought to explore whether resuscitation of injured patients with a balanced crystalloid solution affects coagulation, as measured by endogenous thrombin potential (ETP) and thromboelastography (TEG). We performed an exploratory analysis of a subset of subjects enrolled in a randomized trial comparing the effect of resuscitation with isotonic saline versus Plasma-Lyte A (PLA) on acidosis and electrolyte abnormalities. We collected plasma at admission and 6 h later for subsequent ETP and TEG analysis and compared subjects receiving isotonic saline to those receiving PLA. Among 18 evaluated subjects, baseline characteristics, including ETP and TEG parameters, were similar between the two arms. At 6 h, subjects receiving isotonic saline were more acidemic. At 6 h, there were no differences in ETP parameters between groups; however, TEG results showed the time from initial clot formation to an amplitude of 20 mm (K) was shorter (3.8 ± 2.1 vs. 7.2 ± 2.8 s) and the rapidity of fibrin build-up and cross-linking (α angle) was significantly greater (41 ± 8 vs. 24 ± 15 deg) for the PLA group than in the isotonic saline group. Relative to PLA, isotonic saline does not alter thrombin generation, but isotonic saline and PLA may differentially impact clotting factor availability. The shorter time to reach prespecified clot amplitude and the increased rate of fibrin generation imply faster amplification of clotting factors with PLA without effect on latency time or clot strength.

Tranexamic acid: from trauma to routine perioperative use

PURPOSE OF REVIEW

Optimizing hemostasis with antifibrinolytics is becoming a common surgical practice. Large clinical studies have demonstrated efficacy and safety of tranexamic acid (TXA) in the trauma population to reduce blood loss and transfusions. Its use in patients without pre-existing coagulopathies is debated, as thromboembolic events are a concern. In this review, perioperative administration of TXA is examined in nontrauma surgical populations. Additionally, risk of thromboembolism, dosing regimens, and timing of dosing are assessed.

RECENT FINDINGS

Perioperative use of TXA is associated with reduced blood loss and transfusions. Thromboembolic effects do not appear to be increased. However, optimal dosing and timing of TXA administration is still under investigation for nontrauma surgical populations.

SUMMARY

As part of a perioperative blood management programme, TXA can be used to help reduce blood loss and mitigate exposure to blood transfusion.

Early inflammatory response in polytraumatized patients: Cytokines and heat shock proteins. A pilot study

INTRODUCTION

In the initial phases after polytrauma there is an hyperinflammatory state that sometimes leads to multiple organ dysfunction syndrome (MODS) and death, and that appears to be responsible for posttraumatic immunosuppression; among the trigger endogenous stimuli, heat shock proteins (HSPs) have been proposed. The objectives of this study were to analyze if some inflammatory mediators can be considered prognostic biomarkers of outcome, and the possible role of HSPA1A in posttraumatic immunosuppression.

HYPOTHESIS

Cytokines and HSPs could be early prognostic biomarkers of inflammatory and immune response in polytrauma patients.

MATERIALS AND METHODS

A prospective observational descriptive pilot study was carried out, evaluating the early inflammatory and stress response of 18 polytraumatized patients (ISS>16) on hospital admission, at 12hours, 24hours, and 48hours posttrauma. Variable means were compared using non-parametric tests; qualitative and quantitative variables were analyzed using a Spearman's correlation test.

RESULTS

Seven patients met criteria for MODS. Statistically significant changes were recorded in leukocyte count, C-reactive-protein (CRP), IL-6, TNF-α, and IL-1ß concentrations. HSPA1A levels were significantly higher immediately after the accident followed by gradual lowering. Anti-Hsp70 antibodies showed a significant reduction in all the studied time-points. MODS did not influence either plasma levels of leukocytes, fibrinogen, RCP or anti-Hsp70, but patients with MODS had higher plasma levels of IL-6 and TNF-α and a slower decrease of HSPA1A concentrations.

DISCUSSION

The higher serum concentrations of TNF-α and IL-6 found in patients with MODS, suggests a possible role as potential early predictive markers for systemic inflammatory response and clinical complications. The higher levels of HSPA1A in patients with MODS, allows proposing HSPA1A as a useful prognostic trauma biomarker early after severe injury and to consider a "damage control surgery". The significant reduction in the levels of anti-Hsp70 antibodies could reflect a part of posttraumatic immunosuppression and hydrocortisone treatment might be suggested.

LEVEL III

case-control study.

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.

An International Normalized Ratio-Based Definition of Acute Traumatic Coagulopathy Is Associated With Mortality, Venous Thromboembolism, and Multiple Organ Failure After Injury

OBJECTIVES

Acute traumatic coagulopathy is associated with adverse outcomes including death. Previous studies examining acute traumatic coagulopathy's relation with mortality are limited by inconsistent criteria for syndrome diagnosis, inadequate control of confounding, and single-center designs. In this study, we validated the admission international normalized ratio as an independent risk factor for death and other adverse outcomes after trauma and compared two common international normalized ratio-based definitions for acute traumatic coagulopathy.

DESIGN

Multicenter prospective observational study.

SETTING

Nine level I trauma centers in the United States.

PATIENTS

A total of 1,031 blunt trauma patients with hemorrhagic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

International normalized ratio exhibited a positive adjusted association with all-cause in-hospital mortality, hemorrhagic shock-associated in-hospital mortality, venous thromboembolism, and multiple organ failure. Acute traumatic coagulopathy affected 50% of subjects if defined as an international normalized ratio greater than 1.2 and 21% of subjects if defined by international normalized ratio greater than 1.5. After adjustment for potential confounders, acute traumatic coagulopathy defined as an international normalized ratio greater than 1.5 was significantly associated with all-cause death (odds ratio [OR], 1.88; p < 0.001), hemorrhagic shock-associated death (OR, 2.44; p = 0.001), venous thromboembolism (OR, 1.73; p < 0.001), and multiple organ failure (OR, 1.38; p = 0.02). Acute traumatic coagulopathy defined as an international normalized ratio greater than 1.2 was not associated with an increased risk for the studied outcomes.

CONCLUSIONS

Elevated international normalized ratio on hospital admission is a risk factor for mortality and morbidity after severe trauma. Our results confirm this association in a prospectively assembled multicenter cohort of severely injured patients. Defining acute traumatic coagulopathy by using an international normalized ratio greater than 1.5 but not an international normalized ratio greater than 1.2 identified a clinically meaningful subset of trauma patients who, adjusting for confounding factors, experienced more adverse outcomes. Targeting future therapies for acute traumatic coagulopathy to patients with an international normalized ratio greater than 1.5 may yield greater returns than using a lower international normalized ratio threshold.

Vasopressin Infusion with Small-Volume Fluid Resuscitation during Hemorrhagic Shock Promotes Hemodynamic Stability and Survival in Swine

Introduction

Current management of hemorrhagic shock (HS) in the battlefield and civilian settings favors small-volume fluid resuscitation before controlling the source of bleeding. We investigated in a swine model of HS the effects of vasopressin infusion along with small-volume fluid resuscitation; with erythropoietin (EPO) and HS severity as additional factors.

Methods

HS was induced in 24 male domestic pigs (36 to 41 kg) by blood withdrawal (BW) through a right atrial cannula modeling spontaneous bleeding by a mono-exponential decay function. The initial 12 pigs received no fluids; the last 12 pigs received normal saline (NS) half the BW volume. Pigs were randomized 2:1 to receive intraosseously vasopressin (0.04 U/kg·min^-1) or vehicle control from minute 7 to minute 210. Pigs assigned to vasopressin were further randomized 1:1 to receive EPO (1,200 U/kg) or vehicle control and 1:1 to have 65% or 75% BW of their blood volume. Shed blood was reinfused at 210 minutes and the pigs recovered from anesthesia.

Results

Survival at 72 hours was influenced by vasopressin and NS but not by EPO or % BW. Vasopressin with NS promoted the highest survival (8/8) followed by vasopressin without NS (3/8), NS without vasopressin (1/4), and neither treatment (0/4) with overall statistical significance (log-rank test, p = 0.009) and each subset different from vasopressin with NS by Holm-Sidak test. Vasopressin increased systemic vascular resistance whereas NS increased cardiac output.

Conclusion

Vasopressin infusion with small-volume fluid resuscitation during severe HS was highly effective enabling critical hemodynamic stabilization and improved 72 hour survival.

Trauma resuscitation and monitoring: military lessons learned

Over the past 13 years, the military health care system has made improvements that are associated with an unprecedented survival rate for severely injured casualties. Monitoring for indications of deterioration as the critically injured patient moves across the continuum of care is difficult given the limitations of routinely used vital signs. Research by both military and civilian researchers is revolutionizing monitoring, with an increased focus on noninvasive, continuous, dynamic measurements to provide earlier, more sensitive indications of the patient's perfusion status.

Damage control resuscitation

The early recognition and management of hemorrhage shock are among the most difficult tasks challenging the clinician during primary assessment of the acutely bleeding patient. Often with little time, within a chaotic setting, and without sufficient clinical data, a decision must be reached to begin transfusion of blood components in massive amounts. The practice of massive transfusion has advanced considerably and is now a more complete and, arguably, more effective process. This new therapeutic paradigm, referred to as damage control resuscitation (DCR), differs considerably in many important respects from previous management strategies for catastrophic blood loss. We review several important elements of DCR including immediate correction of specific coagulopathies induced by hemorrhage and management of several extreme homeostatic imbalances that may appear in the aftermath of resuscitation. We also emphasize that the foremost objective in managing exsanguinating hemorrhage is always expedient and definitive control of the source of bleeding.

Elevated tissue plasminogen activator and reduced plasminogen activator inhibitor promote hyperfibrinolysis in trauma patients

Severe hyperfibrinolysis after trauma is a poorly understood phenomenon associated with profound shock, serious anatomic injuries, increased transfusions, and high mortality rates. Molecular mechanisms driving hyperfibrinolysis in trauma have not been completely delineated. The authors aimed to determine the relationship between severe hyperfibrinolysis and outcomes in trauma patients and characterize the role of the plasminogen activator (PA) system in this condition. A prospective observational study was performed in 163 adult level I trauma patients admitted between April and August 2012. Blood was collected on admission, and fibrinolysis was determined by plasmin-α2 antiplasmin (PAP) levels. Tissue-derived and urokinase PA (tPA and uPA, respectively), PA inhibitor (PAI-1), fibrinogen, and antithrombin levels were also measured. Patient demographics, vital signs, laboratory values, mechanisms and severity of injuries, transfusions, and outcomes were collected at admission or from patient records. Moderate fibrinolysis was defined as PAP level 1,500 to 20,000 μg/L and severe hyperfibrinolysis as PAP level more than 20,000 μg/L. Severe hyperfibrinolysis was observed in 10% of patients and associated with increased injury severity, greater transfusions, fewer ventilator and hospital-free days, and higher mortality. Plasmin-α2 antiplasmin level was directly correlated with tPA level and inversely correlated with PAI-1 level. Patients with both elevated tPA and reduced PAI-1 were more severely injured, received more transfusions, and experienced fewer ventilator and hospital-free days. In conclusion, Severe hyperfibrinolysis is observed in a small percentage of trauma patients and is associated with severe injuries, greater transfusions, and worse outcomes. This condition is mediated, in part, by excessive upregulation of profibrinolytic tPA in the absence of concomitant increases in antifibrinolytic PAI-1.

The serum- & glucocorticoid-inducible kinase in the regulation of platelet function

The serum- and glucocorticoid-inducible kinase 1 (SGK1) is expressed in megakaryocytes and circulating platelets. In megakaryocytes, SGK1 activates transcription factor nuclear factor kappa-B (NF-κB), which in turn stimulates expression of Orai1, a Ca(2+) channel protein accomplishing store-operated Ca(2+) enrty (SOCE). SGK1 enhances SOCE and several Ca(2+) -sensitive platelet functions, including degranulation, integrin αII b β3 activation, phosphatidylserine exposure, aggregation and thrombus formation. As shown in other cell types, stimulators of SGK1 expression include ischaemia, oxidative stress, hyperglycaemia, advanced glycation end products (AGEs) and a variety of hormones such as glucocorticoids, mineralocorticoids, transforming growth factor beta (TGFβ), interleukin 6 (IL-6), platelet-derived growth factor (PDGF), thrombin and endothelin. Thus, SGK1-sensitive Ca(2+) signalling may contribute to altered platelet function in several clinical conditions including inflammation, metabolic syndrome, diabetes mellitus and chronic renal failure. Nevertheless, further studies are needed defining the contribution of altered SGK1 expression and activity to physiology and pathophysiology of platelets.

Prothrombin complex concentrate in trauma patients

BACKGROUND

Despite recent advances, trauma care providers nowadays face a number of coagulopathic patients. Coagulopathy in trauma patients can be secondary to the traumatic insult or therapeutic effect of the anticoagulants including the Vitamin K antagonist. The efficacy of a concentrated product of Vitamin K-dependent coagulation factors, prothrombin complex concentrate (PCC), to reverse coagulopathy has been tested mainly in nontrauma setting.

DATA SOURCES

Currently available literature on the use of PCC was identified by searches of electronic database. The indications (trauma vs nontrauma) and types of the PCC products (3 vs 4 factors) were also reviewed in each article.

CONCLUSIONS

There are small studies that show promising results regarding PCC use to reverse the Vitamin K antagonist-related coagulopathy in trauma patients. It remains unanswered whether PCC can be effective as an adjunct in patients who require massive transfusion.

Traumatic brain injury is not associated with coagulopathy out of proportion to injury in other body regions

BACKGROUND

Coagulopathy following trauma is associated with poor outcomes. Traumatic brain injury has been associated with coagulopathy out of proportion to other body regions. We hypothesized that injury severity and shock determine coagulopathy independent of body region injured.

METHODS

We performed a prospective, multicenter observational study at three Level 1 trauma centers. Conventional coagulation tests (CCTs) and rapid thrombelastography (r-TEG) were used. Admission vital signs, base deficit (BD), CCTs, and r-TEG data were collected. The Abbreviated Injury Scale (AIS) score and Injury Severity Score (ISS) were obtained. Severe injury was defined as AIS score greater than or equal to 3 for each body region. Patients were grouped according to their dominant AIS region of injury. Dominant region of injury was defined as the single region with the highest AIS score. Patients with two or more regions with the same greatest AIS score and patients without a region with an AIS score greater than or equal to 3 were excluded. Coagulation parameters were compared between the dominant AIS region. Significant hypoperfusion was defined as BD greater than or equal to 6.

RESULTS

Of the 795 patients enrolled, 462 met criteria for grouping by dominant AIS region. Patients were predominantly white (59%), were male (75%), experienced blunt trauma (71%), and had a median ISS of 25 (interquartile range, 14-29). Patients with BD greater than or equal to 6 (n = 110) were hypocoagulable by CCT and r-TEG compared with patients with BD less than 6 (n = 223). Patients grouped by dominant AIS region showed no significant differences for any r-TEG or CCT parameter. Patients with BD greater than or equal to 6 demonstrated no difference in any r-TEG or CCT parameter between dominant AIS regions.

CONCLUSION

Coagulopathy results from a combination of tissue injury and shock independent of the dominant region of injury. With the use of AIS as a measure of injury severity, traumatic brain injury was not independently associated with more profound coagulopathy.

LEVEL OF EVIDENCE

Epidemiologic study, level III.

Acute traumatic coagulopathy in the setting of isolated traumatic brain injury: Definition, incidence and outcomes

BACKGROUND AND OBJECTIVES

Acute traumatic coagulopathy (ATC) has been reported in the setting of isolated traumatic brain injury (iTBI) and associated with poor outcomes. Among patients with iTBI, we aimed to select an appropriate definition of ATC, outline the incidence of ATC and examine clinical variables associated with ATC.

METHODS

A retrospective review of The Alfred Trauma Registry was conducted and patients with iTBI (head AIS [Abbreviated Injury Score] ≥ 3 and all other body regions AIS < 3) were selected for analysis. The association of the international normalised ratio (INR) on arrival at hospital with the mortality on hospital discharge was explored, to select an appropriate clinical horizon to define ATC. The incidence of ATC was calculated using this definition. Injury and clinical variables measurable pre-hospital and immediately on arrival at the hospital were analysed to determine independent associations with ATC.

RESULTS

There were 1718 patients with iTBI included in the study. The overall mortality was 12%, but significantly greater when initial INR was measured at ≥ 1.3 (45.1%; p < 0.01). The proportion of patients with ATC, using this definition, was 7.7% (95% CI: 6.5-9.0). The pre-hospital variables independently associated with ATC in the setting of iTBI were age (OR 1.02, 95% CI 1.01-1.03), shock index (SI) of ≥ 1 (OR 1.68, 95% CI 1.01-2.79) and abnormal pupils (OR 8.33, 95% CI 4.50-15.89). The presence of at least two factors, of age > 50 yrs, SI ≥ 1, or abnormal pupils, was 97.54% (95% CI: 96.6-98.2) specific for ATC.

CONCLUSIONS

An abnormal initial INR in the setting of iTBI was associated with poor outcomes, regardless of magnitude. The incidence of ATC appears too low to recommend empiric pro-coagulant management for all patients with iTBI. The subgroup of patients older than 50 yrs., with shock or abnormal size of pupils, may be considered for interventional trials of early treatment against ATC.

An engineered factor Va prevents bleeding induced by anticoagulant wt activated protein C

OBJECTIVE

An increased risk of bleeding is observed in patients receiving activated protein C (APC), which may be a limiting factor for the application of novel APC therapies. Since APC's therapeutic effects often require its cytoprotective activities on cells but not APC's anticoagulant activities, an agent that specifically antagonizes APC's anticoagulant effects but not its cytoprotective effects could provide an effective means to control concerns for risk of bleeding. We hypothesized that superFVa, an engineered activated FVa-variant that restores hemostasis in hemophilia could reduce APC-induced bleeding.

APPROACH AND RESULTS

SuperFVa was engineered with mutations of the APC cleavage sites (Arg506/306/679Gln) and a disulfide bond (Cys609-Cys1691) between the A2 and A3 domains, which augment its biological activity and cause high resistance to APC. SuperFVa normalized APC-prolonged clotting times and restored APC-suppressed thrombin generation in human and murine plasma at concentrations where wild-type (wt) FVa did not show effects. Following intravenous injection of APC into BALB/c mice, addition to whole blood ex vivo of superFVa but not wt-FVa significantly normalized whole blood clotting. Blood loss following tail clip or liver laceration was significantly reduced when superFVa was administered intravenously to BALB/c mice prior to intravenous APC-treatment. Furthermore, superFVa abolished mortality (∼50%) associated with excessive bleeding following liver laceration in mice treated with APC.

CONCLUSIONS

Our results provide proof of concept that superFVa is effective in preventing APC-induced bleeding and may provide therapeutic benefits as a prohemostatic agent in various situations where bleeding is a serious risk.

Coagulopathy after severe pediatric trauma

Trauma remains the leading cause of morbidity and mortality in the United States among children aged 1 to 21 years. The most common cause of lethality in pediatric trauma is traumatic brain injury. Early coagulopathy has been commonly observed after severe trauma and is usually associated with severe hemorrhage and/or traumatic brain injury. In contrast to adult patients, massive bleeding is less common after pediatric trauma. The classical drivers of trauma-induced coagulopathy include hypothermia, acidosis, hemodilution, and consumption of coagulation factors secondary to local activation of the coagulation system after severe traumatic injury. Furthermore, there is also recent evidence for a distinct mechanism of trauma-induced coagulopathy that involves the activation of the anticoagulant protein C pathway. Whether this new mechanism of posttraumatic coagulopathy plays a role in children is still unknown. The goal of this review is to summarize the current knowledge on the incidence and potential mechanisms of coagulopathy after pediatric trauma and the role of rapid diagnostic tests for early identification of coagulopathy. Finally, we discuss different options for treating coagulopathy after severe pediatric trauma.

Acute traumatic coagulopathy in the setting of isolated traumatic brain injury: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Acute traumatic coagulopathy (ATC) has been reported in the setting of isolated traumatic brain injury (iTBI) and associated with high mortality and poor outcomes. The aim of this systematic review was to examine the incidence and outcome of patients with ATC in the setting of iTBI.

METHODS

We conducted a search of the MEDLINE database and Cochrane library, focused on subject headings and keywords involving coagulopathy and TBI. Design and results of each study were described. Studies were assessed for heterogeneity and the pooled incidence of ATC in the setting of iTBI determined. Reported outcomes were described.

RESULTS

There were 22 studies selected for analysis. A statistically significant heterogeneity among the studies was observed (p<0.01). Using the random effects model the pooled proportion of patients with ATC in the setting of iTBI was 35.2% (95% CI: 29.0-41.4). Mortality of patients with ATC and iTBI ranged between 17% and 86%. Higher blood transfusion rates, longer hospital stays, longer ICU stays, decreased ventilator free days, higher rates of single and multiple organ failure and higher incidence of delayed injury and disability at discharge were reported among patients with ATC.

CONCLUSIONS

ATC is commonly associated with iTBI and almost uniformly associated with worse outcomes. Any disorder of coagulation above the normal range appears to be associated with worse outcomes and therefore a clinically important target for management. Earlier identification of patients with ATC and iTBI, for recruitment into prospective trials, presents avenues for further research.

Tranexamic acid corrects fibrinolysis in the presence of acidemia in a swine model of severe ischemic reperfusion

BACKGROUND

Tranexamic acid (TXA) is an antifibrinolytic with anti-inflammatory properties associated with improved outcomes when administered to trauma patients at risk for bleeding; however, its efficacy is unknown in acidemia. We evaluated the efficacy of TXA on hyperfibrinolysis using an established porcine traumatic hemorrhage ischemic shock model.

METHODS

Ten Yorkshire swine underwent a controlled hemorrhage followed by supraceliac aortic cross-clamping. During standard resuscitation, control animals received recombinant tissue plasminogen activator (rtPA) after cross-clamp removal, and experimental animals received rtPA followed by TXA. Rotational thromboelastometry analysis was performed at baseline, 5 minutes and 15 minutes after rtPA dosing, and 4 hours after cross-clamp removal.

RESULTS

Control and experimental animals had similar hemodynamics and routine laboratory values at baseline and throughout resuscitation. At the time of TXA administration, average pH was 7.2. Clot formation time was prolonged from baseline and all resuscitation time points in both groups, with no difference at any time point. Maximum clot firmness decreased from baseline at all resuscitation time points in both groups. Maximum lysis increased from baseline (9% control vs. 9% TXA) after tissue plasminogen activator administration in both groups (100% control vs. 99% TXA). In experimental animals, maximum lysis returned to baseline 10 minutes after TXA administration (92% vs. 9%, p < 0.001).

CONCLUSION

TXA rapidly and fully reverses hyperfibrinolysis despite severe acidemia in a porcine trauma model. TXA is a promising adjunct to trauma resuscitation that is easily administered in austere or prehospital settings.

Damage Control Resuscitation In Trauma

INTRODUCTION

Most preventable trauma deaths are due to uncontrolled hemorrhage.

METHODS

In this article, we briefly describe the pathophysiology of the classical triad of death in trauma, namely, acidosis, hypothermia, and coagulopathy, and then suggest damage control resuscitation strategies to prevent and/or mitigate the effects of each in the bleeding patient.

RESULTS

Damage control resuscitation strategies include body rewarming, restrictive fluid administration, permissive hypotension, balanced blood product administration, and the implementation of massive transfusion protocols.

CONCLUSION

Resuscitating and correcting the coagulopathy of the exsanguinating trauma patient is essential to improve chances of survival.

Hemostasis during the early stages of trauma: comparison with disseminated intravascular coagulation

INTRODUCTION

We tested two hypotheses that disseminated intravascular coagulation (DIC) and acute coagulopathy of trauma-shock (ACOTS) in the early phase of trauma are similar disease entities and that the DIC score on admission can be used to predict the prognosis of patients with coagulopathy of trauma.

METHODS

We conducted a retrospective study of 562 trauma patients, including 338 patients whose data were obtained immediately after admission to the emergency department. We collected serial data for the platelet counts, global markers of coagulation and fibrinolysis, and antithrombin levels. DIC was diagnosed according to the Japanese Association for Acute Medicine (JAAM) DIC scoring system, and ACOTS was defined as a prothrombin-time ratio of >1.2.

RESULTS

The higher levels of fibrin/fibrinogen degradation products (FDP) and D-dimer and greater FDP/D-dimer ratios in the DIC patients suggested DIC with the fibrinolytic phenotype. The DIC patients with the fibrinolytic phenotype exhibited persistently lower platelet counts and fibrinogen levels, increased prothrombin time ratios, higher FDP and D-dimer levels, and lower antithrombin levels compared with the non-DIC patients on arrival to the emergency department and during the early stage of trauma. Almost all ACOTS patients met the criteria for a diagnosis of DIC; therefore, the same changes were observed in the platelet counts, global markers of coagulation and fibrinolysis, and antithrombin levels as noted in the DIC patients. The JAAM DIC score obtained immediately after arrival to the emergency department was an independent predictor of massive transfusion and death due to trauma and correlated with the amount of blood transfused.

CONCLUSIONS

Patients who develop DIC with the fibrinolytic phenotype during the early stage of trauma exhibit consumption coagulopathy associated with increased fibrin(ogen)olysis and lower levels of antithrombin. The same is true in patients with ACOTS. The JAAM DIC score can be used to predict the prognosis of patients with coagulopathy of trauma.

Acute coagulopathy of trauma: Mechanism, monitoring, management

Coagulopathy is a well-known consequence of trauma and is the most common cause of mortality in the young. However, its cause and management is still controversial. A new concept in the understanding of coagulopathy in trauma is the occurrence of Acute coagulopathy of trauma (ACoT). ACoT is associated with hypo perfusion and tissue trauma as seen in massive injury. The incidence of coagulopathy increases with injury scores and is associated with higher number of ventilator days, higher morbidity and mortality. The process of coagulation is better described by the cell based model with a central role for platelets rather than the older plasma based model. This shift in our understanding supports the theory that ACoT results from the endothelial release of thrombomodulin and activated protein C in the presence of hypoperfusion. This in turn leads on to a hyperfibrinolytic and hypocoagulable state. Viscoelastic hemostatic assays are replacing the older tests like prothrombin time in the assessment of coagulopathy. These tests are accurate, determine the need for transfusion and can be performed at the point of care. Damage control resuscitation includes newer concepts like permissive hypotension, increased use of plasma as a part of massive transfusion protocols and damage control surgery.

TEG and ROTEM: technology and clinical applications

Initially described in 1948 by Hertert thromboelastography (TEG) provides a real-time assessment of viscoelastic clot strength in whole blood. Rotational thromboelastometry (ROTEM) evolved from TEG technology and both devices generate output by transducing changes in the viscoelastic strength of a small sample of clotting blood (300 µl) to which a constant rotational force is applied. These point of care devices allow visual assessment of blood coagulation from clot formation, through propagation, and stabilization, until clot dissolution. Computer analysis of the output allows sophisticated clot formation/dissolution kinetics and clot strength data to be generated. Activation of clot formation can be initiated with both intrinsic (kaolin, ellagic acid) and extrinsic (tissue factor) activators. In addition, the independent contributions of platelets and fibrinogen to final clot strength can be assessed using added platelet inhibitors (abciximab and cytochalasin D). Increasingly, ROTEM and TEG analysis is being incorporated in vertical algorithms to diagnose and treat bleeding in high-risk populations such as those undergoing cardiac surgery or suffering from blunt trauma. Some evidence suggests these algorithms might reduce transfusions, but further study is needed to assess patient outcomes.

The Pathophysiology and Management of Acute Traumatic Coagulopathy

Acute traumatic coagulopathy (ATC) is commonly seen among patients with severe injury and will lead to uncontrolled bleeding diathesis, which is an important contributor to trauma death. During the past 10 years, the understanding of the mechanism causing ATC has changed rapidly. The mechanisms for ATC are complicated. To date, the possible mechanisms include activation of protein C, shedding of endothelial glycocalyx, catecholamine release, platelet dysfunction, primary, and secondary fibrinolysis, with tissue injury and hypoperfusion as the triggers. Classic factors such as dilution, acidosis, and hypothermia can further aggravate the coagulopathy. Inflammation may have a potential effect on the onset and prognosis of ATC. With the aid of diagnostic device, the outcome can be improved through early and customized treatment. Antifibrinolytics such as tranexamic acid has some benefits in patients with bleeding trauma, especially in the early time. This review presents the current understanding of ATC mechanisms and management.

Hyperosmolar reconstituted lyophilized plasma is an effective low-volume hemostatic resuscitation fluid for trauma

BACKGROUND

We performed this study to optimize reconstituted lyophilized plasma (LP) into a minimal volume fluid that provides effective hemostatic resuscitation for trauma while minimizing logistical limitations.

METHODS

We performed a prospective, blinded animal study. Plasma was lyophilized following whole blood collection from anesthetized swine. The minimal volume needed for reconstitution was determined, and this solution was evaluated for safe infusion into the swine. Reconstituted LP was analyzed for electrolyte content, osmolarity, and coagulation factor activity. Twenty swine were anesthetized and subjected to a validated model of polytrauma and hemorrhagic shock (including a Grade V liver injury), then randomized to resuscitation with LP reconstituted to either 100% of the original plasma volume (100%LP) or the minimal volume LP fluid. Physiologic data were monitored, and blood loss and hematocrit were measured. Coagulation status was evaluated using thrombelastography.

RESULTS

The minimal volume of reconstituted LP safe for infusion in swine was 50% of the original plasma volume (50%LP). The 50%LP had higher electrolyte concentrations, osmolarity, and increased coagulation factor activity levels by volume compared with 100%LP (p < 0.05). Blood loss, hematocrit, mean arterial pressure, and heart rate did not differ between animals receiving 100%LP (n = 10) or 50%LP (n = 10) at any time point (p > 0.05). International normalized ratio and thrombelastography parameters were not different between groups (R time, α angle, or maximal amplitude, p > 0.05).

CONCLUSION

Resuscitation with 50%LP fluid was well tolerated and equally effective compared with 100%LP, with respect to physiologic and hemostatic properties. The smaller volume of fluid necessary to reconstitute hypertonic LP makes it logistically superior to 100%LP for first responders and may reduce adverse effects of large-volume resuscitation.

Role of fibrinogen in cerebrovascular dysfunction after traumatic brain injury

Traumatic brain injury (TBI) has been associated with various neurological disorders. However, the role of cerebrovascular dysfunction and its mechanisms associated with TBI are still not well understood. Inflammation is the main cause of vascular dysfunction. It affects properties of blood components and the vascular wall leading to changes in blood flow and in interaction of blood components and vascular endothelium exacerbating microcirculatory complications during inflammatory diseases. One of the markers of inflammation is a plasma adhesion protein, fibrinogen (Fg). At elevated levels, Fg can also cause inflammatory responses. One of the manifestations of inflammatory responses is an increase in microvascular permeability leading to accumulation of plasma proteins in the subendothelial matrix and causing vascular remodelling. This has a most devastating effect on cerebral circulation after TBI that is accompanied with an elevation of plasma level of Fg and with an increased cerebrovascular permeability in injury penumbra impairing the normal healing process. This study reviews cerebrovascular alterations after TBI, considers the consequences of increased blood-brain barrier permeability, defines the role of elevated level of Fg and discusses the potential mechanisms of its action leading to vascular dysfunction, which subsequently can cause impairment in neuronal function. Thus, possible mechanisms of vasculo-neuronal dysfunction after TBI are considered.

Time course of soluble P-selectin and von Willebrand factor levels in trauma patients: a prospective observational study

Background

Coagulopathy often develops in patients with serious trauma and is correlated with the clinical outcome. The contribution of platelet activity and endothelial dysfunction to trauma-induced coagulopathy remain to be defined. The purpose of this study was to investigate the time courses of soluble P-selectin (sPsel, an index of platelet activation) and von Willebrand factor (VWF, an index of endothelial dysfunction) in trauma patients and elucidate their relationship to coagulation parameter levels, the presence of coagulopathy, and patient outcome.

Methods

This prospective observational study, which took place in a university hospital intensive care unit (ICU), included 82 severely injured trauma patients. The sPsel, VWF antigen, protein C, and factor VII levels were measured and routine coagulation tests were performed upon admission to ICU and daily within the first week. The 30-day mortality rate was also determined.

Results

Thirty-seven (45.1%) patients developed coagulopathy upon admission to the ICU, and the 30-day mortality rate was 20.7% (n = 17). Both the admission sPsel and VWF levels were lower in patients with coagulopathy than in those without (p < 0.05) and were significantly correlated with the protein C and factor VII levels, respectively (all p < 0.05). The VWF levels were lower during the first 3 days and higher on day 7 after admission in nonsurvivors than in survivors (all p < 0.05). No significant differences in sPsel levels were found between nonsurvivors and survivors on each day during the first week.

Conclusion

In severely injured trauma patients in the ICU, lower levels of sPsel and VWF on admission were associated with the presence of coagulopathy and might not predict a better outcome. An increase in the VWF level at the end of the first week after admission to ICU was associated with increased 30-day mortality.

Thrombelastography (TEG®): practical considerations on its clinical use in trauma resuscitation

Background

Thrombelastography is a laboratorial test that measures viscoelastic changes of the entire clotting process. There is growing interest in its clinical use in trauma resuscitation, particularly for managing acute coagulopathy of trauma and assisting decision making concerning transfusion. This review focuses on the clinical use of thrombelastography in trauma, with practical points to consider on its use in civilian and military settings.

Methods

A search in the literature using the terms “thrombelastography AND trauma” was performed in PUBMED database. We focused the review on the main clinical aspects of this viscoelastic method in diagnosing and treating patients with acute coagulopathy of trauma during initial resuscitation.

Results

Thrombelastography is not a substitute for conventional laboratorial tests such as INR and aPTT but offers additional information and may guide blood transfusion. Thrombelastography can be used as a point of care test but requires multiple daily calibrations, should be performed by trained personnel and its technique requires standardization. While useful partial results may be available in minutes, the whole test may take as long as other conventional tests. The most important data provided by thrombelastography are clot strength and fibrinolysis. Clot strength measure can establish whether the bleeding is due to coagulopathy or not, and is the key information in thrombelastography-based transfusion algorithms. Thrombelastography is among the few tests that diagnose and quantify fibrinolysis and thus guide the use of anti-fibrinolytic drugs and blood products such as cryoprecipitate and fibrinogen concentrate. It may also diagnose platelet dysfunction and hypercoagulability and potentially prevent inappropriate transfusions of hemostatic blood products to non-coagulopathic patients.

Conclusions

Thrombelastography has characteristics of an ideal coagulation test for use in early trauma resuscitation. It has limitations, but may prove useful as an additional test. Future studies should evaluate its potential to guide blood transfusion and the understanding of the mechanisms of trauma coagulopathy.

Blood Far Forward--a whole blood research and training program for austere environments

The Blood Far Forward (BFF) research program was established to conduct blood product efficacy and safety studies, donor performance studies, and research on optimal training methods to improve the safety of blood collection and transfusion performed by Norwegian Naval Special Operation Commando soldiers. The use of intravenous fluids for volume replacement during hemorrhagic shock is controversial, but it is currently the standard of care. In the far-forward environment, large volume resuscitation for massive bleeding is a great challenge. Crystalloid and colloid solutions add weight and bulk to the medic's kit, require temperature sensitive storage, and should be warmed before infusion to prevent hypothermia. Excessive use of these solutions causes a dilutional coagulopathy, acidosis, and potentially increased inflammatory injury compared with blood products. Type-specific whole blood from an uninjured combat companion on the other hand is almost always available. It is warm, replaces intravascular volume, and provides oxygen delivery and hemostatic capacity to prevent or treat shock and coagulopathy. Whole blood may be ideal for the resuscitation of combat casualties with hemorrhagic shock. BFF program pilot studies on use of platelet-sparing leukoreduction filters, whole blood transport tolerance, donor performance, and autologous reinfusion of 24-hour ambient temperature stored whole blood have been performed and suggest the feasibility of expanding whole blood use in resuscitation. If successful, the BFF program will change tactics, techniques, and procedures with a new lifesaving capability.