Trauma-Induced Coagulopathy: An Institution's 35 Year Perspective on Practice and Research

Sex dimorphisms in coagulation: Implications in trauma-induced coagulopathy and trauma resuscitation

Trauma-induced coagulopathy (TIC) is one of the leading causes of preventable death in injured patients. Consequently, it is imperative to understand the mechanisms underlying TIC and how to mitigate this mortality. An opportunity for advancement stems from the awareness that coagulation demonstrates a strong sex-dependent effect. Females exhibit a relative hypercoagulability compared to males, which persists after injury and confers improved outcomes. The mechanisms underlying sex dimorphisms in coagulation and its protective effect after injury have yet to be elucidated. This review explores sex dimorphisms in enzymatic hemostasis, fibrinogen, platelets, and fibrinolysis, with implications for resuscitation of patients with TIC.

Assessment of ethynylestradiol-3-sulfate on coagulation, metabolism, and survival in pigs with traumatic hemorrhage

BACKGROUND

The beneficial effects of estrogens on survival from hemorrhage have been suggested in some preclinical models. This study investigated the effects of ethynylestradiol-3-sulfate (EE-3-S) on coagulation, metabolism and survival in pigs following traumatic hemorrhage.

METHODS

Twenty-six pigs were randomized into: normal saline group (NS, n = 10), EE-3-S group (EE-3, n = 11) groups, and no resuscitation group (NR, n = 5). Femur fracture was performed in each pig's left leg, followed by hemorrhage of 55% of estimated blood volume and a 10-minute shock period. Afterward, pigs were resuscitated with a small volume of either NS alone (4 mL/kg) or EE-3-S with NS (1 mL/kg at concentration of 1 mg/mL, plus NS solution of 3 mL/kg). Pigs in NR group were not resuscitated with any fluid. All pigs were then monitored for 6 hours or until death, with hemodynamics and survival times recorded. Blood samples were taken during the study for measurements of oxygen metabolism (oxygen delivery, extraction, and consumption) and coagulation function (using Rotem with Extem reagents).

RESULTS

All baseline measurements were similar among the three groups. In the NS group, femur fracture and hemorrhage immediately reduced mean arterial pressure (MAP, 74 ± 3 mm Hg to 44 ± 4 mm Hg) and increased heart rate (97 ± 5 bpm to 218 ± 14 bpm, both p < 0.05). Similar changes in MAP and heart rate were observed in the EE-3 and NR groups. There were no differences observed in changes of Rotem ® measurements or oxygen metabolism among the groups during the study. At 6 hours, four pigs in NS, four pigs in EE-3-S, and two pigs in the NR group survived to the end of the study. The mean survival times were similar among the NS (212 ± 43 minutes), EE-3 (212 ± 39 minutes), and NR (223 ± 63 minutes) groups ( p = 0.9845).

CONCLUSION

Following severe traumatic hemorrhage, hypotensive resuscitation with EE-3-S did not impact coagulation, metabolism, or survival in pigs.

Apolipoprotein A-I, elevated in trauma patients, inhibits platelet activation and decreases clot strength

Apolipoprotein A-I (ApoA-I) is elevated in the plasma of a subgroup of trauma patients with systemic hyperfibrinolysis. We hypothesize that apoA-I inhibits platelet activation and clot formation. The effects of apoA-I on human platelet activation and clot formation were assessed by whole blood thrombelastography (TEG), platelet aggregometry, P-selectin surface expression, microfluidic adhesion, and Akt phosphorylation. Mouse models of carotid artery thrombosis and pulmonary embolism were used to assess the effects of apoA-I in vivo. The ApoA-1 receptor was investigated with transgenic mice knockouts (KO) for the scavenger receptor class B member 1 (SR-BI). Compared to controls, exogenous human apoA-I inhibited arachidonic acid and collagen-mediated human and mouse platelet aggregation, decreased P-selectin surface expression and Akt activation, resulting in diminished clot strength and increased clot lysis by TEG. ApoA-I also decreased platelet aggregate size formed on a collagen surface under flow. In vivo, apoA-I delayed vessel occlusion in an arterial thrombosis model and conferred a survival advantage in a pulmonary embolism model. SR-BI KO mice significantly reduced apoA-I inhibition of platelet aggregation versus wild-type platelets. Exogenous human apoA-I inhibits platelet activation, decreases clot strength and stability, and protects mice from arterial and venous thrombosis via the SR-BI receptor.

Does the mechanism matter? Comparing thrombelastography between blunt and penetrating pediatric trauma patients

BACKGROUND/PURPOSE

The utility of thrombelastography (TEG) in pediatric trauma remains unknown, and differences in coagulopathy between blunt and penetrating mechanisms are not established. We aimed to compare TEG patterns in pediatric trauma patients with blunt solid organ injuries (BSOI) and penetrating injuries to determine the role of mechanism in coagulopathy.

METHODS

Highest-level pediatric trauma activations with BSOI or penetrating injuries and admission TEG at two pediatric trauma centers were included. TEG abnormalities were defined by each institution's normative values and compared separately by injury mechanism and evidence of shock (elevated SIPA) using Kruskal-Wallis or Fisher's exact tests.

RESULTS

Of 118 patients included, 64 had BSOI and 54 had penetrating injuries. There were no significant differences in TEG abnormalities between the BSOI and penetrating injury groups. Patients with shock were more likely to have decreased alpha-angles (30.9% vs. 8.0%, p = 0.01) and decreased maximum amplitude (MA) (44.1% vs. 8.0%, p < 0.001) compared to those without shock, regardless of mechanism of injury.

CONCLUSIONS

TEG abnormalities were not significantly different between the BSOI and penetrating groups, but there were significant differences in alpha-angle and MA in those with shock, independent of mechanism. Hemodynamic status, rather than mechanism of injury, may be more predictive of coagulopathy in pediatric trauma patients.

LEVEL OF EVIDENCE/STUDY TYPE

Level III, retrospective.

Snake Venom Hydrogels as a Rapid Hemostatic Agent for Uncontrolled Bleeding

Uncontrolled bleeding from traumatic injury remains the leading cause of preventable death with loss of balance between blood clotting (coagulation) and blood clot breakdown (fibrinolysis). A major limitation of existing hemostatic agents is that they require a functioning clotting system to control the bleeding and are largely based on gauze delivery scaffolds. Herein, a novel rapid wound sealant, composed of two recombinant snake venom proteins, the procoagulant ecarin, to rapidly initiate blood clotting and the antifibrinolytic textilinin, to prevent blood clot breakdown within a synthetic thermoresponsive hydrogel scaffold is developed. In vitro, it is demonstrated that clotting is rapidly initiated with only nanomolar concentrations of venom protein and clot breakdown is effectively inhibited by textilinin. A stable clot is formed within 60 s compared to normal clot formation in 8 min. In vivo studies reveal that the snake venom hydrogel rapidly controls warfarin-induced bleeding, reducing the bleed volume from 48% to 12% and has demonstrated immune compatibility. A new class of hemostatic agents that achieve formation of rapid and stable blood clots even in the presence of blood thinners is demonstrated here.

Percutaneous delivery of self-propelling hemostatic powder for managing non-compressible abdominal hemorrhage: a proof-of-concept study in swine

INTRODUCTION

Non-compressible intra-abdominal hemorrhage (NCIAH) is a major cause of preventable death on the battlefield and in civilian trauma. Currently, it can only be definitively managed with surgery, as there are limited strategies for controlling ongoing NCIAH in the prehospital environment. We hypothesized that a self-propelling thrombin-containing powder (SPTP) could increase survival in a swine model of NCIAH when delivered percutaneously into the closed abdomen using an engineered spray system.

MATERIALS AND METHODS

Nineteen swine underwent surgical laparotomy followed by a Grade V liver injury that created massive hemorrhage, before closing the abdomen with sutures. Animals either received treatment with standard of care fluid resuscitation (n=9) or the SPTP spray system (n=10), which consisted of a spray device and a 14 Fr catheter. Using the spray system, SPTP was delivered into a hemoperitoneum identified using a focused assessment with sonography in trauma (FAST) exam. Lactated Ringer's solution was administered to all animals to maintain a mean arterial pressure (MAP) of >50 mmHg. The primary outcome was percentage of animals surviving at three hours following injury.

RESULTS

In the swine model of NCIAH, a greater percentage of animals receiving SPTP survived to three hours, although differences were not significant. The SPTP spray system increased the median survival of animals from 1.6 hr in the fluid resuscitation group to 4.3 hr. The SPTP spray system delivered a total mass of 18.5 ± 1.0 g of SPTP. The mean change in intra-abdominal pressure following SPTP delivery was 5.2 ± 1.8 mmHg (mean ± SEM). The intervention time was 6.7 ± 1.7 min. No adverse effects related to the SPTP formulation or the spray system were observed. SPTP was especially beneficial in animals that had either severely elevated lactate concentrations or low mean arterial pressure of <35 mmHg shortly after injury.

CONCLUSIONS

This demonstrates proof-of-concept for use of a new minimally invasive procedure for managing NCIAH, which could extend survival time to enable patients to reach definitive surgical care.

Application of thromboelastography in diagnosing normal pregnancies and pregnancies with complications

Background

This observational study aimed to compare the potential application of thromboelastography (TEG) in diagnosing women with normal pregnancy (NP) and women with threatened abortion (TA), missed abortion (MA), embryo arrest (EA), fetal death (FD), history of abnormal pregnancy (HAP), and antiphospholipid antibody syndrome (AA).

Methods

According to the relevant clinical criteria, patients were divided into groups, and their blood samples were subjected to TEG. Next, the parameters R, K, α‐angle, MA, LY‐30, G, and coagulation index (CI) were analyzed. Partial correlation analysis was used to analyze correlation between groups of data. LSD‐t test and Dunnett's T3 test were used to analyze continuous variables. Ordinal categorical variables were compared using ordinal logistic regression analysis and estimate odds ratio of risk factors. A receiver operating characteristic (ROC) curve was constructed to detect the ability of TEG to recognize various parameters, and areas under the curve were compared using Delong's test for diagnosing pregnancy‐related diseases.

Results

MA had a negative effect on the MA parameter in TEG; EA had a negative effect on the MA and G parameters; HAP had a negative effect on the CI parameter and a positive effect on the R parameter; AA had a negative effect on the CI parameter. Compared with that of the NP group, the G of the EA (p = 0.014) group and the CI of the TA (p = 0.036) MA (p = 0.08) EA (p = 0.026) HAP (p = 0.000004) and AA (p = 0.002) groups were reduced. In the ordinal logistic regression analysis, compared with that of the NP group, the high R value of the HAP group accounted for more than that of the NP group (OR = 48.76, p = 0.001); the high K value of the AA group accounted for more than that of the NP group (OR = 17.00, p = 0.023); the angle value distributions of the TA and AA groups were different from that of the NP group (OR = 3.30, p = 0.039; OR = 0.14, p = 0.029); the low MA value of the MA, EA, and HAP groups accounted for more than that of the NP group (OR = 0.16, p = 0.03; OR = 0.26, p = 0.005; OR = 0.11, p = 0.008); and the low CI value of the HAP group accounted for more than that of the NP group (OR = 0.09, p = 0.005). In the ROC analysis, there were no significant differences in the TEG parameters of pregnant women belonging to the NP and TA, NP and MA, NP and EA, NP and FD, NP and HAP, and NP and AA groups (p > 0.05).

Autoresuscitation of Poloxamer 188 in Pigs With Traumatic Severe Hemorrhage

BACKGROUND

Poloxamer 188 (P188) is a copolymer surfactant with plasma membrane stabilizing action. This study investigated the effects of P188 on blood volume and coagulation in pigs after traumatic hemorrhage and hypotensive resuscitation.

METHODS

Femur fracture was performed in 17 anesthetized pigs, followed by hemorrhage of 55% of estimated blood volume and a 10 min shock period. Afterwards, pigs were randomized to be resuscitated with either normal saline (n = 9, 4 mL/kg, NS group) or P188 (n = 8, 1.33 mL/kg at 150 mg/mL, plus 2.67 mL NS/kg, P188 group). Pigs were monitored for 2 h or until death. Hemodynamics were recorded and blood samples were taken at baseline (BL), after hemorrhage, shock, resuscitation, and at 2 h for blood and coagulation analysis using Rotem®.

RESULTS

All but one pig in each group survived to 2 h. Femur fracture and hemorrhage reduced mean arterial pressure to half of the BL and elevated heart rate to double of the BL (both P < 0.05). Resuscitation with NS or P188 did not return these measurements to BL. Compared to NS, resuscitation with P188 resulted in a smaller reduction of blood volume (76 ± 3% in P188 and 60 ± 2% in NS); higher base excess (3.3 ± 0.9 vs. 0.5 ± 0.9 mM); and lower hematocrit (24 ± 1 vs. 28 ± 1%) and Ca++ (24 ± 1 vs. 28 ± 1 mM). Resuscitation with P188 prolonged aPTT (43 ± 12 vs. 22 ± 3 s, all P < 0.05).

CONCLUSIONS

Following traumatic hemorrhage and hypotensive resuscitation, P188 improved circulation volume and base deficit, but induced slower clotting initiation in pigs. Thus, P188 may have limited benefit as an initial small volume resuscitation adjunct following hemorrhage.

Emerging gene therapies for enhancing the hemostatic potential of platelets

Platelet transfusions are an integral component of balanced hemostatic resuscitation protocols used to manage severe hemorrhage following trauma. Enhancing the hemostatic potential of platelets could lead to further increases in the efficacy of transfusions, particularly for non-compressible torso hemorrhage or severe hemorrhage with coagulopathy, by decreasing blood loss and improving overall patient outcomes. Advances in gene therapies, including RNA therapies, are leading to new strategies to enhance platelets for better control of hemorrhage. This review will highlight three approaches for creating modified platelets using gene therapies: (i) direct transfection of transfusable platelets ex vivo, (ii) in vitro production of engineered platelets from platelet-precursor cells, and (iii) modifying the bone marrow for in vivo production of modified platelets. In summary, modifying platelets to enhance their hemostatic potential is an exciting new frontier in transfusion medicine, but more preclinical development as well as studies testing the safety and efficacy of these agents are needed.

Effects of dexmedetomidine on blood coagulation: an in vitro study using rotational thromboelastometry

PURPOSE

To assess the effects of various concentrations of dexmedetomidine on the human blood coagulation profile using rotational thromboelastometry (ROTEM).

METHODS

Venous blood samples were collected from 11 healthy volunteers and divided into four specimen bottles; dexmedetomidine was added to attain final sample concentrations of 0, 0.5, 1.0, and 1.5 ng/mL. ROTEM was performed on each study sample.

RESULTS

The concentration of dexmedetomidine increased, and the ROTEM values showed a hypercoagulable state. The change in clotting time (CT) for INTEM was larger in samples with a dexmedetomidine concentration of 1.5 ng/mL (- 34%) than in the 0.5 ng/mL samples (- 16%) (P = 0.010). The change in clot formation time (CFT) for INTEM was greater in 1.5 ng/mL samples (- 16%) than in 0.5 ng/mL samples (- 4%) (P = 0.004). A greater decrease in CT for EXTEM was identified in the 1.0 ng/mL and 1.5 ng/mL samples (- 36% and - 37%, respectively) than in the 0.5 ng/mL samples (- 12%) (P = 0.003 for both categories). The change in CFT for EXTEM was greater in the 1.0 ng/mL and 1.5 ng/mL samples (- 11% and - 13%, respectively) than in the 0.5 ng/mL samples (- 4%) (P = 0.006 and P = 0.001, respectively). A bigger change in maximum clot firmness (MCF) for EXTEM was observed in the 1.5 ng/mL samples (4%) than in the 0.5 ng/mL samples (0%) (P = 0.002). The change in MCF for FIBTEM was greater in the 1.5 ng/mL samples (19%) than in the 0.5 ng/mL samples (5%) (P = 0.001).

CONCLUSIONS

All coagulation pathways showed a hypercoagulable state as the concentration of dexmedetomidine increased. Nevertheless, most of the values of ROTEM were maintained within the reference ranges. Clinical Trial NCT04269278.

The swine as a vehicle for research in trauma-induced coagulopathy: Introducing principal component analysis for viscoelastic coagulation tests

BACKGROUND

Uncontrolled bleeding is the leading cause of potentially preventable deaths among trauma patients. Tissue injury and shock result in trauma-induced coagulopathy (TIC). There are still uncertainties regarding detection methods and best practice management for TIC, and a deeper understanding of the pathophysiology requires robust animal models. The applicability of swine in coagulation studies, particularly after trauma has not been sufficiently elucidated. We, therefore, evaluated the swine as a vehicle for TIC research in a selection of trauma modalities.

METHODS

Twenty-six landrace swine (3 females/23 males) (mean weight, 60.0 kg) were anesthetized and randomized to negative controls, receiving no manipulation (n = 5), positive controls by hemodilution (n = 5), pulmonary contusion without hemorrhage (n = 5), pulmonary contusion with hemorrhage (n = 5), and blast polytrauma with hypothermia, hypoperfusion, hypoventilation, and systemic inflammation (n = 6). A comprehensive coagulation panel was analyzed at baseline, 20 minutes and 120 minutes after trauma.

RESULTS

PT(INR), aPTT, thrombocytes, and fibrinogen did not change after trauma. D-dimer increased (p < 0.0001), prothrombin decreased (p < 0.05) and aPC decreased (p < 0.01) after polytrauma. PAI-1 decreased after pulmonary contusion with hemorrhage (p < 0.05). Positive controls displayed changes in PT(INR), thrombocytes, fibrinogen, prothrombin, aPC (p < 0.05). Principal Component Analysis of rotational thromboelastometry presented pathologic coagulation profiles in both polytrauma and positive control groups with vectors extending outside the 95% confidence interval, which were not detected in negative controls.

CONCLUSION

Coagulopathy was induced after severe porcine blast polytrauma, specifically detected in rotational thromboelastometry. A novel method for principal component analysis of viscoelastic tests was introduced which may increase the detection sensitivity and differentiation of TIC phenotypes and should be further investigated in trauma populations.

Efficacy of resuscitation with fibrinogen concentrate and platelets in traumatic hemorrhage swine model

BACKGROUND

This study compared the resuscitation effects of platelets and fibrinogen concentrate (FC) on coagulation and hemodynamics in pigs with traumatic hemorrhage and reduced platelet counts.

METHODS

Thirty pigs (40 ± 3 kg) were anesthetized and catheterized with an apheresis catheter to remove platelets using the Haemonetics 9000 (Haemonetics, Braintree, MA). Afterward, a femur fracture was induced, followed by hemorrhage of 35% the estimated blood volume. Pigs were then randomized to be resuscitated with 5% human albumin (12.5 mL/kg), FC (250 mg/kg, 12.5 mL/kg), or platelets collected from apheresis (11.0 ± 0.5 mL/kg). Animals were monitored for 2 hours or until death. Blood samples were collected before (baseline [BL]) and after apheresis, after hemorrhage, and after resuscitation to assess changes in hemodynamics and coagulation using Rotem.

RESULTS

No change in mean arterial pressure (MAP) or heart rate (HR) was observed by platelet apheresis. Hemorrhage reduced MAP to 57% ± 5% and elevated HR to 212% ± 20% of BL (both p < 0.05). Resuscitation with albumin, FC, or platelets did not revert MAP or HR to BL. Platelet counts were reduced by apheresis from BL 383 ± 20 × 10/μL to 141 ± 14 × 10/μL and were reduced further after resuscitation with albumin (88 ± 18 × 10/μL) or FC (97 ± 13 × 10/μL, all p < 0.05), but improved with platelet resuscitation (307 ± 24 × 10/μL). Fibrinogen concentration was reduced by apheresis from BL 225 ± 9 mg/dL to 194 ± 8 mg/dL, fell after albumin infusion (134 ± 11 mg/dL), increased to 269 ± 10 mg/dL after FC resuscitation (all p < 0.05), and was not affected by platelet resuscitation. Rotem α-angle decreased from 79 ± 2 degrees to 69 ± 1 degrees by apheresis and hemorrhage (p < 0.05), and recovered similarly by resuscitation with FC (87 ± 1 degrees) or platelets (78 ± 2 degrees), but not by albumin (63 ± 3 degrees). Similar responses were observed in Rotem maximum clot firmness.

CONCLUSION

In this traumatic hemorrhage swine model, low-volume resuscitation with FC or platelets was similarly effective in restoring coagulation.

Does the Degree of Platelet Adenosine Diphosphate and Arachidonic Acid Receptor Inhibition Correlate With the Severity of Injury in Non-Brain-Injured Trauma Patients?

BACKGROUND

Direct correlations between platelet adenosine diphosphate (ADP) and arachidonic acid (AA) receptor inhibition have been described in the traumatic brain injury (TBI) population. Our goal was to evaluate the percent inhibition of ADP receptor inhibition (ADPri) and AA receptor inhibition (AAri) receptors in non-TBI patients and correlate injury severity and outcomes.

METHODS

We performed a retrospective review of non-TBI patients admitted to our trauma center, who received thromboelastography with platelet mapping prior to blood transfusion. Exclusion criteria included patients younger than 18 years, current antiplatelet therapy, or history of renal failure. Univariate descriptive statistics and bivariate comparisons were performed on patient demographic and outcomes. Multivariable linear regression models were constructed to quantify any association between ADPri and AAri with injury outcomes. High ADP inhibition was defined >20% and high AA inhibition >7%.

RESULTS

117 patients met inclusion criteria. Mean age was 53 years with 61% male. Mean ADPri was 64% and AAri 42%. On bivariate analysis, no statistically significant differences with respect to injury severity measures or outcomes were identified. On multivariable linear regression, AAri was associated with longer hospital length of stay.

DISCUSSION

There was a high degree of platelet dysfunction in this cohort of severely injured patients without TBI. Despite this, the only correlation identified between injury severity and outcomes was AAri correlating with hospital length of stay. Irrespective of injury severity or outcomes, these patients' results were far from reported "normal" values. Further, research is needed to determine the significance and clinical implications of thromboelastography with platelet mapping use in trauma care.

Creatine kinase is associated with bleeding after myocardial infarction

BACKGROUND

The ADP-scavenging enzyme creatine kinase (CK) is reported to reduce ADP-dependent platelet activation. Therefore, we studied whether highly elevated CK after ST-elevation myocardial infarction (STEMI) is associated with bleeding.

METHODS

Data of the Thrombolysis in Myocardial Infarction Study Group phase II trial on the efficacy of angioplasty, following intravenous recombinant tissue-type plasminogen activator (rt-PA), are used to assess whether peak plasma CK (CKmax) is independently associated with adjudicated fatal or non-fatal bleeding (primary) and combined bleeding/all-cause mortality (secondary) in multivariable binomial logistic regression analysis, adjusting for baseline and treatment allocation covariates.

RESULTS

The included patients (n=3339, 82% men, 88% white, mean age 57 years, SE 0.2) had a history of angina pectoris (55%), hypertension (38%) and/or diabetes mellitus (13%). CKmax ranged from 16 to 55 890 IU/L (mean 2389 IU/L, SE 41), reached within 8 hours in 51% of the patients (93% within 24 hours). Adjudicated fatal/non-fatal bleeding occurred in 30% of the patients (respectively 26% in the low vs 34% in the high CK tertile), and bleeding/all-cause mortality in 35% (29% in the low vs 40% in the high CK tertile). In multivariable regression analysis, the adjusted OR for fatal/non-fatal bleeding (vs not bleeding and survival) was 2.6 (95% CI 1.8 to 3.7)/log CKmax increase, and 3.1 (2.2 to 4.4) for bleeding/all-cause mortality.

CONCLUSION

Highly elevated plasma CK after myocardial infarction might be an independent predictor of bleeding and haemorrhagic death. This biologically plausible association warrants further prospective study of the potential role of extracellular CK in ADP-dependent platelet activation and bleeding.

Characterizing Early Inpatient Death After Trauma

BACKGROUND

There is a paucity of data to predict early death or futility after trauma. The objective of this study was to characterize the laboratory values, blood product administration, and hospital disposition for patients with trauma who died within 72 h of admission.

METHODS

All deaths within 72 h of admission over a 5-y period at a level I trauma center were reviewed. Blood transfusion within the first 4 h of arrival and patient disposition from the emergency department to the operating room (OR), surgical intensive care unit, or the neuroscience intensive care unit (NSICU) were analyzed. Kaplan-Meier curves were generated to determine time to death.

RESULTS

A total of 622 subjects were identified; 39.5% died in the emergency department, 10.6% went directly to the OR, 13.6% were admitted to the surgical intensive care unit, and 29.7% admitted to the NSICU. Of these subjects, 201 (32.2%) patients received blood within the first 4 h. By 24 h, early blood transfusion was associated with more rapid death for patients who were admitted to the NSICU (80% versus 60% mortality, P = 0.01) but not for patients taken directly to the OR (80% versus 70% mortality, P = 0.2). Admission coagulopathy by international normalized ratio (P < 0.01), but not anemia (P = 0.64) or acidosis (P = 0.45), correlated with a shorter time to death. In contrast, laboratory values obtained at 4 h after admission did not correlate with time to death.

CONCLUSIONS

Our data demonstrate that admission coagulation derangement and need for early blood product transfusion are the two factors most associated with early death after injury, particularly in those patients with traumatic brain injury. These data will help construct future models for futility of continued care in patients with trauma.

Bloodletting Puncture at Hand Twelve Jing-Well Points Improves Neurological Recovery by Ameliorating Acute Traumatic Brain Injury-Induced Coagulopathy in Mice

Traumatic brain injury (TBI) contributes to hypocoagulopathy associated with prolonged bleeding and hemorrhagic progression. Bloodletting puncture therapy at hand twelve Jing-well points (BL-HTWP) has been applied as a first aid measure in various emergent neurological diseases, but the detailed mechanisms of the modulation between the central nervous system and systemic circulation after acute TBI in rodents remain unclear. To investigate whether BL-HTWP stimulation modulates hypocoagulable state and exerts neuroprotective effect, experimental TBI model of mice was produced by the controlled cortical impactor (CCI), and treatment with BL-HTWP was immediately made after CCI. Then, the effects of BL-HTWP on the neurological function, cerebral perfusion state, coagulable state, and cerebrovascular histopathology post-acute TBI were determined, respectively. Results showed that BL-HTWP treatment attenuated cerebral hypoperfusion and improve neurological recovery post-acute TBI. Furthermore, BL-HTWP stimulation reversed acute TBI-induced hypocoagulable state, reduced vasogenic edema and cytotoxic edema by regulating multiple hallmarks of coagulopathy in TBI. Therefore, we conclude for the first time that hypocoagulopathic state occurs after acute experimental TBI, and the neuroprotective effect of BL-HTWP relies on, at least in part, the modulation of hypocoagulable state. BL-HTWP therapy may be a promising strategy for acute severe TBI in the future.

Von Willebrand factor as a thrombotic and inflammatory mediator in critical illness

The endothelial exocytosis of high-molecular-weight multimeric von Willebrand factor (vWF) may occur in critical illness states, including trauma and sepsis, leading to the sustained elevation and altered composition of plasma vWF. These critical illnesses involve the common process of sympathoadrenal activation and loss of the endothelial glycocalyx. As a prothrombotic and proinflammatory molecule that interacts with the endothelium, the alterations exhibited by vWF in critical illness have been implicated in the development and damaging effects of downstream pathologies, such as disseminated intravascular coagulation and systemic inflammatory response syndrome. Given the role of vWF in these pathologies, there has been a recent push to further understand how the molecule may be involved in the pathophysiology of related diseases, such as trauma-induced coagulopathy and acute renal injury, which are also known to develop secondarily to critical illness states. Elucidation of the role of vWF across the broader spectrum of generalized pathologies may provide a basis for the development of novel preventative and restorative measures, while also bolstering the scaffold of more widely used treatments, such as the administration of plasma-containing blood products.

Hemostatic Balance in Severe Trauma

Acute coagulopathy is prevalent in adult and pediatric trauma patients and is associated with increased morbidity and mortality. While reasonable hypotheses have been created to explain the underlying perturbations of adult trauma coagulopathy (i.e., tissue factor-related increase in thrombin generation, protein C activation, hypoperfusion, and hyperfibrinolysis), only a small number of studies have been performed to prove whether these mechanisms can likewise be detected in pediatric trauma patients. In addition, severe hypofibrinogenemia (<100 mg/dL) is a frequent finding in pediatric trauma patients (>20%). Although the probability of life-threatening coagulopathy is low with minor to moderate injury, it is present in almost all patients with an injury severity score >25, hypotension, hypothermia, and acidosis. As these multifactorial changes in hemostasis cannot be adequately and rapidly measured using standard laboratory testing, the use of viscoelastic measurements has been established in adult trauma management, but prospective studies in children are urgently needed. Apart from diagnostic challenges, several studies have focused on the impact of blood product ratios on the treatment of massively bleeding pediatric trauma patients. The majority of these studies were unable to show improved survival by using higher plasma to red blood cell ratios or higher platelet to red blood cells ratios, but there are no published randomized trials to definitively answer this question. A goal-directed transfusion protocol using viscoelastic tests together with early substitution with an antifibrinolytic and fibrinogen replacement is a promising alternative to traditional ratio-based interventions. Another crucial factor in treating trauma-induced coagulopathy is the early detection of hypofibrinogenemia, a common condition in massively transfused patients. Early treatment of hypofibrinogenemia is associated with improved morbidity and mortality in adults, but needs to be further studied in future pediatric trials. Pediatric trauma patients are not only threatened by coagulopathy-related bleeding but are also at higher risk for venous thromboembolism. Pediatric trauma patients with brain injury, central venous catheters, immobilization, or surgical procedures are at highest risk for developing a deep venous thrombosis. There are no specific pediatric guidelines established to prevent venous thromboembolism in children suffering from traumatic injury.

Topical tranexamic acid inhibits fibrinolysis more effectively when formulated with self-propelling particles

BACKGROUND

Endogenous fibrinolytic activation contributes to coagulopathy and mortality after trauma. Administering tranexamic acid (TXA), an antifibrinolytic agent, is one strategy to reduce bleeding; however, it must be given soon after injury to be effective and minimize adverse effects. Administering TXA topically to a wound site would decrease the time to treatment and could enable both local and systemic delivery if a suitable formulation existed to deliver the drug deep into wounds adequately.

OBJECTIVES

To determine whether self-propelling particles could increase the efficacy of TXA.

METHODS

Using previously developed self-propelling particles, which consist of calcium carbonate and generate CO2 gas, TXA was formulated to disperse in blood and wounds. The antifibrinolytic properties were assessed in vitro and in a murine tail bleeding assay. Self-propelled TXA was also tested in a swine model of junctional hemorrhage consisting of femoral arteriotomy without compression.

RESULTS

Self-propelled TXA was more effective than non-propelled formulations in stabilizing clots from lysis in vitro and reducing blood loss in mice. It was well tolerated when administered subcutaneously in mice up to 300 to 1000 mg/kg. When it was incorporated in gauze, four of six pigs treated after a femoral arteriotomy and without compression survived, and systemic concentrations of TXA reached approximately 6 mg/L within the first hour.

CONCLUSIONS

A formulation of TXA that disperses the drug in blood and wounds was effective in several models. It may have several advantages, including supporting local clot stabilization, reducing blood loss from wounds, and providing systemic delivery of TXA. This approach could both improve and simplify prehospital trauma care for penetrating injury.

Hemostatic Management of Trauma-Induced Coagulopathy

Trauma-induced coagulopathy is a primary factor in many trauma-related fatalities. Management hinges upon rapid diagnosis of coagulation abnormalities and immediate administration of appropriate hemostatic agents. Use of crystalloids and packed red blood cells has traditionally been the core of trauma resuscitation, but current massive transfusion protocols include combination therapy with fresh frozen plasma and predefined ratios of platelets to packed red blood cells, limiting crystalloid administration. Hemostatic agents such as tranexamic acid, prothrombin complex concentrate, fibrinogen concentrate, and, in cases of refractory bleeding, recombinant activated factor VIIa may also be warranted. Goal-directed resuscitation using viscoelastic tools allows specific component-centered therapy based on individual clotting abnormalities that may limit blood product use and thromboembolic risks and may lead to reduced mortality. Because of the complex management of patients with trauma-induced coagulopathy, critical care nurses must be familiar with the pathophysiology, acute diagnostics, and pharmacotherapeutic options used to treat these patients.

Current trends in the management of hemodynamically unstable pelvic ring injuries

PURPOSE OF REVIEW

Complex traumatic pelvic ring disruptions are associated with a high mortality rate due to associated retroperitoneal hemorrhage, traumatic-hemorrhagic shock, and postinjury coagulopathy. The present review provides an update on current management strategies to improve survival rates form hemodynamically unstable pelvic ring injuries.

RECENT FINDINGS

Recently published international consensus guidelines have attempted to standardize the classification of hemodynamically unstable pelvic ring injuries and provided classification-based management algorithms for acute resuscitation and pelvic ring stabilization.

SUMMARY

Acute management strategies for pelvic ring disruptions with associated hemorrhagic shock include resuscitative endovascular balloon occlusion of the aorta for patients 'in extremis' in conjunction with point-of-care guided resuscitation for postinjury coagulopathy. Recent data indicate that a protocol of early pelvic external fixation in conjunction with direct preperitoneal pelvic packing and subsequent angioembolization in patients with ongoing hemorrhage results in significantly improved survival from retroperitoneal exsanguinating hemorrhage in at-risk patients with historic mortality rates as high as 50-60%.

Rapid TEG efficiently guides hemostatic resuscitation in trauma patients

BACKGROUND

Several thrombelastography functional assays have been developed to guide transfusion in injured patients, but how this acceleration of thrombelastography affects its ability to predict massive transfusion is unknown. The objective of this study is to compare citrated native, citrated kaolin, and citrated rapid thromboelastographies for their prediction of massive transfusion after trauma. We hypothesized that citrated native thrombelastography best predicts massive transfusion.

METHODS

Data were collected as part of a prospective study of trauma activation patients. All patients received citrated native, citrated kaolin, or citrated rapid thromboelastographies. Logistic regression was used to assess the predictive performance of different thrombelastography assays for massive transfusion.

RESULTS

Measurements for all three TEG activating systems was available for 343 patients; 57 (16.6%) required a massive transfusion. Compared to citrated rapid thromboelastographies, citrated kaolin thromboelastographies performed better for activated clotting time/rapid and citrated native thromboelastographies for maximum amplitude and angle. Yet, the 95% confidence intervals overlapped considerably, suggesting the citrated rapid thromboelastographies produced comparable results to the other assays for activated clotting time/reaction time, maximum amplitude, and angle.

CONCLUSION

There was substantial overlap in the performance of the different thrombelastography assays, suggesting citrated rapid thrombelastography is a quick and effective method to guide hemostatic resuscitation in trauma patients and does not perform inferiorly to the citrated native or citrated kaolin thrombelastography despite the addition of activation factors.

Improving Pharmacologic Prevention of VTE in Trauma: IMPACT-IT QI Project

Enoxaparin regimens commonly used for prophylaxis fail to achieve optimal anti-factor Xa levels in up to 70 per cent of trauma patients. Accordingly, trauma services at the study institution endeavored to develop a standardized approach to optimize pharmacologic prevention with enoxaparin. An enoxaparin venous thromboembolism (VTE) prophylaxis protocol implemented in October 2015 provided weight-adjusted initial dosing parameters with subsequent dose titration to achieve targeted anti-factor Xa levels. Symptomatic VTE rate was evaluated 12 months pre- and post-implementation. Data were obtained from the trauma registry and charts were reviewed from electronic medical records. The rate of symptomatic VTE significantly declined post-implementation (2.0% vs 0.9%, P = 0.009). Enoxaparin use was comparable in these two phases validating that the decline in symptomatic VTEs was not due to an increase in enoxaparin use. Symptomatic VTE rate for patients who received enoxaparin in the post-implementation cohort decreased from 3.2 to 1.0 per cent (P = 0.023, 95% confidence interval = 0.124–0.856). There was also a significant decrease in the rate of symptomatic deep vein thrombosis (2.8% vs 0.9%, P = 0.040, 95% confidence interval = 0.117–0.950). This approach to VTE prophylaxis with enoxaparin resulted in a significant reduction in symptomatic VTE rates. Implementation of similar practices may be equally impactful in other institutions that use enoxaparin.

Improving Pharmacologic Prevention of VTE in Trauma: IMPACT-IT QI Project

Enoxaparin regimens commonly used for prophylaxis fail to achieve optimal anti-factor Xa levels in up to 70 per cent of trauma patients. Accordingly, trauma services at the study institution endeavored to develop a standardized approach to optimize pharmacologic prevention with enoxaparin. An enoxaparin venous thromboembolism (VTE) prophylaxis protocol implemented in October 2015 provided weight-adjusted initial dosing parameters with subsequent dose titration to achieve targeted anti-factor Xa levels. Symptomatic VTE rate was evaluated 12 months pre- and post-implementation. Data were obtained from the trauma registry and charts were reviewed from electronic medical records. The rate of symptomatic VTE significantly declined post-implementation (2.0% vs 0.9%, P = 0.009). Enoxaparin use was comparable in these two phases validating that the decline in symptomatic VTEs was not due to an increase in enoxaparin use. Symptomatic VTE rate for patients who received enoxaparin in the post-implementation cohort decreased from 3.2 to 1.0 per cent (P = 0.023, 95% confidence interval = 0.124-0.856). There was also a significant decrease in the rate of symptomatic deep vein thrombosis (2.8% vs 0.9%, P = 0.040, 95% confidence interval = 0.117-0.950). This approach to VTE prophylaxis with enoxaparin resulted in a significant reduction in symptomatic VTE rates. Implementation of similar practices may be equally impactful in other institutions that use enoxaparin.

Thromboelastography does not provide additional information to guide resuscitation in the severely injured

Background

Haemostasis assessment is essential to determine the early need for massive transfusion in the treatment of polytrauma. Strategies to guide correction of coagulopathy vary widely. In order to evaluate thromboelastography (TEG) for this goal, a prospective study was performed comparing TEG to conventional coagulation assays (CCAs) in severely injured patients.

Methods

Consecutive polytrauma patients admitted to the intensive care unit of a level‐1 trauma centre were prospectively included over a 30‐month period. All patients had CCA on arrival in emergency department. Patients who needed massive transfusion and underwent urgent surgery had additionally a Kaolin‐activated TEG.

Results

One hundred and thirty‐five patients were included, 76% male, median age 45 years, 96% blunt injuries and median injury severity score was 29. One hundred and fourteen patients had CCA only and 21 patients had both CCA and TEG. Patients who had both CCA and TEG were acidotic, hypothermic and coagulopathic on arrival in emergency department. All 21 patients had normal TEG results even though prothrombin time was prolonged.

Conclusions

TEGs were normal in all polytrauma patients even though patients were severely injured. They had prolonged prothrombin time, acidosis and hypothermia both on arrival and when TEG was measured. Caution should be exercised in interpretation of TEG results in treating polytrauma patients. In our system, with aggressive early haemostatic resuscitation, TEG does not provide additional information in guiding resuscitation.

ClotChip: A Microfluidic Dielectric Sensor for Point-of-Care Assessment of Hemostasis

This paper describes the design, fabrication, and testing of a microfluidic sensor for dielectric spectroscopy of human whole blood during coagulation. The sensor, termed ClotChip, employs a three-dimensional, parallel-plate, capacitive sensing structure with a floating electrode integrated into a microfluidic channel. Interfaced with an impedance analyzer, the ClotChip measures the complex relative dielectric permittivity, ϵ_r , of human whole blood in the frequency range of 40 Hz to 100 MHz. The temporal variation in the real part of the blood dielectric permittivity at 1 MHz features a time to reach a permittivity peak, , as well as a maximum change in permittivity after the peak, , as two distinct parameters of ClotChip readout. The ClotChip performance was benchmarked against rotational thromboelastometry (ROTEM) to evaluate the clinical utility of its readout parameters in capturing the clotting dynamics arising from coagulation factors and platelet activity. exhibited a very strong positive correlation ( r = 0.99, p < 0.0001) with the ROTEM clotting time parameter, whereas exhibited a strong positive correlation (r = 0.85,  p < 0.001) with the ROTEM maximum clot firmness parameter. This paper demonstrates the ClotChip potential as a point-of-care platform to assess the complete hemostatic process using <10 μL of human whole blood.

Damage Control Resuscitation for Catastrophic Bleeding

The timely recognition of shock secondary to hemorrhage from severe facial trauma or as a complication of complex oral and maxillofacial surgery presents formidable challenges. Specific hemostatic disorders are induced by hemorrhage and several extreme homeostatic imbalances may appear during or after resuscitation. Damage control resuscitation has evolved from massive transfusion to a more complex therapeutic paradigm that includes hemodynamic resuscitation, hemostatic resuscitation, and homeostatic resuscitation. Definitive control of bleeding is the principal objective of any comprehensive resuscitation scheme for hemorrhagic shock.

Nonhuman primate model of polytraumatic hemorrhagic shock recapitulates early platelet dysfunction observed following severe injury in humans

BACKGROUND

Platelet dysfunction has been described as an early component of trauma-induced coagulopathy. The platelet component of trauma-induced coagulopathy remains to be fully elucidated and translatable animal models are required to facilitate mechanistic investigations. We sought to determine if the early platelet dysfunction described in trauma patients could be recapitulated in a nonhuman primate model of polytraumatic hemorrhagic shock.

METHODS

Twenty-four male rhesus macaques weighting 7 to 14 kg were subjected to 60 minutes (min) of severe pressure-targeted controlled hemorrhagic shock (HS) with and without other injuries. After 60 min, resuscitation with 0.9% NaCl and whole blood was initiated. Platelet counts and platelet aggregation assays were performed at baseline (BSLN), end of shock (EOS; T = 60 min), end of resuscitation (EOR; T = 180 min), and T = 360 min on overall cohort. Results are reported as mean ± standard deviation (SD) or median (interquartile range). Statistical analysis was conducted using Spearmen correlation, one-way analysis of variance, two-way repeated-measures analysis of variance, paired t-test or Wilcoxon nonparametric test, with p < 0.05 considered significant.

RESULTS

Platelet count in all injury cohorts decreased over time, but no animals developed thrombocytopenia. Correlations were observed between platelet aggregation and platelet count for all agonists: adenosine diphosphate, thrombin recognition-activating peptide-6, collagen, and arachidonic acid. Overall, compared to BSLN, platelet aggregation decreased for all agonist at EOS, EOR, and T = 360 min. When normalized to platelet count, platelet aggregation in response to agonist thrombin recognition-activating peptide-6 demonstrated no change from BSLN at subsequent time points. Aggregation to adenosine diphosphate was significantly less at EOR but not EOS or T = 360 min compared to BSLN. Platelet aggregation to collagen and arachidonic acid was not significantly different at EOS compared to BSLN but was significantly less at EOR and T = 360 min.

CONCLUSION

Nonhuman primates manifest early platelet dysfunction in response to polytraumatic hemorrhagic shock, consistent with that reported in severely injured human patients. Nonhuman primate models potentially are translationally valuable for understanding the mechanisms and pathophysiology of trauma-induced platelet dysfunction.

Acute traumatic coagulopathy in a critically injured pediatric population: Definition, trend over time, and outcomes

BACKGROUND

While our understanding of acute traumatic coagulopathy (ATC) in adults is advancing, the pediatric literature on ATC is limited. Children have a unique injury profile and physiologic response to trauma; however, the impact of this phenomenon on ATC has not been fully elucidated.

METHODS

We performed a retrospective review of our trauma registry from 2005 to 2014. Level 1 trauma patients age 0 year to 17 years requiring admission to the intensive care unit were included. Variables included admission vital signs and laboratory studies, product transfusion, injuries, and mortality. Youden index was used to determine optimum cutoff point for admission international normalized ratio (INR) as a predictor of mortality. Logistic regression modeling was used to determine independent predictors of mortality adjusting for hypotension, hypothermia, acidosis, injury severity, hemorrhage, and head injury. χ tests were performed evaluating for association between mortality and 24-hour INR as well as between transfusion and INR correction.

RESULTS

A total of 776 patients were analyzed: 29.2% (n = 227) had an admission INR of 1.3 or greater, and 13.3% (n = 103) had an admission INR of 1.5 or greater. Youden index demonstrated optimum cutoff at INR of 1.3 or greater to distinguish survivors and nonsurvivors. Overall mortality rate was 11.1% (n = 86). Elevated INR was independently associated with mortality (odds ratio, 3.77; p < 0.001) after controlling for other predictors in regression modeling. Death was also associated with elevated INR at 24 hours and worsening INR trend over time. Patients who received plasma were equally likely to normalize their INR compared with those who were not transfused (p = nonsignificant). Findings were consistent across age groups.

CONCLUSION

INR likely serves as a marker of systemic dysregulation rather than a treatment target in ATC. Elevated admission INR, elevated INR at 24 hours, and overall trend in INR strongly predict mortality in a diverse pediatric trauma population; however, product transfusion did not influence the INR trend or clinical outcome. Further research is warranted to evaluate potential upstream mediators of ATC and targets for intervention in pediatric trauma patients.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III.

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.

Hypotension and the need for transfusion in pediatric blunt spleen and liver injury: An ATOMAC+ prospective study

PURPOSE

Children with blunt liver or spleen injury (BLSI) requiring early transfusion may present without hypotension despite significant hypovolemia. This study sought to determine the relationship between early transfusion in pediatric BLSI and hypotension.

METHODS

Secondary analysis of a 10-institution prospective observational study was performed of patients 18years and younger presenting with BLSI. Patients with central nervous system (CNS) injury were excluded. Children receiving blood transfusion within 4h of injury were evaluated. Time to first transfusion, vital signs, and physical exams were analyzed. Patients with hypotension were compared to those without hypotension.

RESULTS

Of 1008 patients with BLSI, 47 patients met inclusion criteria. 22 (47%) had documented hypotension. There was no statistical difference in median time to first transfusion for those with or without hypotension (2h vs. 2.5h, p=0.107). The hypotensive group was older (median 15.0 versus 9.5years; p=0.007). Median transfusion volume in the first 24h was 18.2mL/kg (IQR: 9.6, 25.7) for those with hypotension and 13.9mL/kg (IQR: 8.3, 21.0) for those without (p=0.220). Mortality was 14% (3/22) in children with hypotension and 0% (0/25) in children without hypotension.

CONCLUSION

Hypotension occurred in less than half of patients requiring early transfusion following pediatric BLSI suggesting that hypotension does not consistently predict the need for early transfusion.

TYPE OF STUDY

Secondary analysis of a prospective observational study.

LEVEL OF EVIDENCE

Level IV cohort study.

Progresses in understanding trauma-induced coagulopathy and the underlying mechanism

Trauma-induced coagulopathy (TIC) is a clinical syndrome caused by imbalance between clotting, anti-coagulation and fibrinolysis resulting from multiple pathological factors such as hemorrhage and tissue injury in the early stage of trauma, and is closely related to the outcome of trauma patients. It is proved in growing evidence that the endogenous coagulation disturbance in trauma itself is the activating factor of TIC, rather than dilution or other acquired coagulopathy. Therefore, a thorough understanding of the molecular mechanisms in the pathogenesis and progression is crucial for effective prevention and treatment in patients with TIC. This review focuses on transitions in the concept of TIC and mechanical progress.

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.

Coagulation complications following trauma

Traumatic injury is one of the leading causes of death, with uncontrolled hemorrhage from coagulation dysfunction as one of the main potentially preventable causes of the mortality. Hypothermia, acidosis, and resuscitative hemodilution have been considered as the significant contributors to coagulation manifestations following trauma, known as the lethal triad. Over the past decade, clinical observations showed that coagulopathy may be present as early as hospital admission in some severely injured trauma patients. The hemostatic dysfunction is associated with higher blood transfusion requirements, longer hospital stay, and higher mortality. The recognition of this early coagulopathy has initiated tremendous interest and effort in the trauma community to expand our understanding of the underlying pathophysiology and improve clinical treatments. This review discusses the current knowledge of coagulation complications following trauma.

Effects of an acidic environment on coagulation dynamics

Essentials Acidosis, an outcome of traumatic injury, has been linked to impaired procoagulant efficiency. In vitro model systems were used to assess coagulation dynamics at pH 7.4 and 7.0. Clot formation dynamics are slightly enhanced at pH 7.0 in blood ex vivo. Acidosis induced decreases in antithrombin efficacy offset impairments in procoagulant activity.

SUMMARY

Background Disruption of hydrogen ion homeostasis is a consequence of traumatic injury often associated with clinical coagulopathy. Mechanisms by which acidification of the blood leads to aberrant coagulation require further elucidation. Objective To examine the effects of acidified conditions on coagulation dynamics using in vitro models of increasing complexity. Methods Coagulation dynamics were assessed at pH 7.4 and 7.0 as follows: (i) tissue factor (TF)-initiated coagulation proteome mixtures (±factor [F]XI, ±fibrinogen/FXIII), with reaction progress monitored as thrombin generation or fibrin formation; (ii) enzyme/inhibitor reactions; and (iii) TF-dependent or independent clot dynamics in contact pathway-inhibited blood via viscoelastometry. Results Rate constants for antithrombin inhibition of FXa and thrombin were reduced by ~ 25-30% at pH 7.0. At pH 7.0 (+FXI), TF-initiated thrombin generation showed a 20% increase in maximum thrombin levels and diminished thrombin clearance rates. Viscoelastic analyses showed a 25% increase in clot time and a 25% reduction in maximum clot firmness (MCF). A similar MCF reduction was observed at pH 7.0 when fibrinogen/FXIII were reacted with thrombin. In contrast, in contact pathway-inhibited blood (n = 6) at pH 7.0, MCF values were elevated 6% (95% confidence interval [CI]: 1%-11%) in TF-initiated blood and 15% (95% CI: 1%- 29%) in the absence of TF. Clot times at pH 7.0 decreased 32% (95% CI: 15%-49%) in TF-initiated blood and 51% (95% CI: 35%-68%) in the absence of TF. Conclusions Despite reported decreased procoagulant catalysis at pH 7.0, clot formation dynamics are slightly enhanced in blood ex vivo and suppression of thrombin generation is not observed. A decrease in antithrombin reactivity is one potential mechanism contributing to these outcomes.

Monitoring time course of human whole blood coagulation using a microfluidic dielectric sensor with a 3D capacitive structure

This paper reports on the design, fabrication, and testing of a microfluidic sensor for dielectric spectroscopy (DS) of human whole blood during coagulation. The sensor employs a three-dimensional (3D), parallel-plate, capacitive sensing structure with a floating electrode integrated into a microfluidic channel. Using an impedance analyzer and after a 5-point calibration, the sensor is shown to measure the real part of complex relative dielectric permittivity of human whole blood in a frequency range of 10kHz to 100MHz. The temporal variation of dielectric permittivity at 1MHz for human whole blood from three different healthy donors shows a peak in permittivity at ~ 4 to 5 minutes, which also corresponds to the onset of CaCl2-initiated coagulation of the blood sample verified visually.

[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.

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.

Clinical presentation and blood gas analysis of multiple trauma patients for prediction of standard coagulation parameters at emergency department arrival

OBJECTIVES

Trauma-induced coagulopathy (TIC) in multiple trauma patients is a potentially lethal complication. Whether quickly available laboratory parameters using point-of-care (POC) blood gas analysis (BGA) may serve as surrogate parameters for standard coagulation parameters is unknown. The present study evaluated TraumaRegister DGU® of the German Trauma Society for correlations between POC BGA parameters and standard coagulation parameters.

METHODS

In the setting of 197 trauma centres (172 in Germany), 86,442 patients were analysed between 2005 and 2012. Of these, 40,129 (72% men) with a mean age 46 ± 21 years underwent further analysis presenting with direct admission from the scene of the accident to a trauma centre, injury severity score (ISS) ≥ 9, complete data available for the calculation of revised injury severity classification prognosis, and blood samples with valid haemoglobin (Hb) measurements taken immediately after emergency department (ED) admission. Correlations between standard coagulation parameters and POC BGA parameters (Hb, base excess [BE], lactate) were tested using Pearson's test with a two-tailed significance level of p < 0.05. A subgroup analysis including patients with ISS > 16, ISS > 25, ISS > 16 and shock at ED admission, and patients with massive transfusion was likewise carried out.

RESULTS

Correlations were found between Hb and prothrombin time (r = 0.497; p < 0.01), Hb and activated partial thromboplastin time (aPTT; r = -0.414; p < 0.01), and Hb and platelet count (PLT; r = 0.301; p < 0.01). Patients presenting with ISS ≥ 16 and shock (systolic blood pressure < 90 mmHg) at ED admission (n = 4,329) revealed the strongest correlations between Hb and prothrombin time (r = 0.570; p < 0.01), Hb and aPTT (r = -0.457; p < 0.01), and Hb and PLT (r = 0.412; p < 0.01). Significant correlations were also found between BE and prothrombin time (r = -0.365; p < 0.01), and BE and aPTT (r = 0.327, p < 0.01). No correlations were found between Hb, BE and lactate lactate.

CONCLUSIONS

POC BGA parameters Hb and BE of multiple trauma patients correlated with standard coagulation parameters in a large database analysis. These correlations were particularly strong in multiple trauma patients presenting with ISS > 16 and shock at ED admission. This may be relevant for hospitals with delayed availability of coagulation studies and those without viscoelastic POC devices. Future studies may determine whether clinical presentation/BGA-oriented coagulation therapy is an appropriate tool for improving outcomes after major trauma.

Thromboelastography predictive of death in trauma patients

OBJECTIVES

To determine if thromboelastography (TEG) is predictive of patient outcomes following traumatic injury.

METHODS

A retrospective review of 131 patients with pelvic trauma admitted to a Level II trauma center was conducted over four years from 1 January 2009 to 31 December 2012. Patients were identified retrospectively from a prospectively collected database of acute pelvic trauma (n = 372). Eligible patients were identified from billing/coding data as having fractures of the acetabulum, iliac wing or sacral alae. Patients with incomplete TEG data were excluded (n = 241), as were patients with pathological fractures. TEG clotting variables and traditional clotting variables were recorded.

RESULTS

Evaluation of TEG data revealed 41 patients with abnormal clotting times (TEG R). TEG R > 6 was an independent risk factor for death (OR, 16; 95%CI 5.4-53; P = 0.0001). The death rate was 52% in patients with TEG R values ≥6 (n = 13/25). There was no significant association between traditional clotting markers and death rate.

CONCLUSIONS

TEG reaction time value, representing the time of initial clot formation, was the only hematologic marker predictive of mortality in patients with pelvic trauma. Delay in reaction time was associated with a significantly increased death rate, independent of injury severity. The death rate association was not observed with traditional markers of clotting. Future prospective studies may be warranted to determine the presentation and significance of TEG abnormalities when resuscitating patients with orthopaedic trauma.

Can the Viscoelastic Parameter α-Angle Distinguish Fibrinogen from Platelet Deficiency and Guide Fibrinogen Supplementation?

Viscoelastic tests such as thrombelastography (TEG, Haemoscope Inc., Niles, IL) and thromboelastometry (ROTEM, Tem International GmbH, Munich, Germany), performed in whole blood, are increasingly used at the point-of-care to characterize coagulopathic states and guide hemostatic therapy. An algorithm, based on a mono-analysis (kaolin-activated assay) approach, was proposed in the TEG patent (issued in 2004) where the α-angle and the maximum amplitude parameters are used to guide fibrinogen supplementation and platelet administration, respectively. Although multiple assays for both the TEG and ROTEM devices are now available, algorithms based on TEG mono-analysis are still used in many institutions. In light of more recent findings, we discuss here the limitations and inaccuracies of the mono-analysis approach. Research shows that both α-angle and maximum amplitude parameters reflect the combined contribution of fibrinogen and platelets to clot strength. Therefore, although TEG mono-analysis is useful for identifying a coagulopathic state, it cannot be used to discriminate between fibrin/fibrinogen and/or platelet deficits, respectively. Conversely, the use of viscoelastic methods where 2 assays can be run simultaneously, one with platelet inhibitors and one without, can effectively allow for the identification of specific coagulopathic states, such as insufficient fibrin formation or an insufficient contribution of platelets to clot strength. Such information is critical for making the appropriate choice of hemostatic therapy.