Trauma hemostasis and oxygenation research position paper on remote damage control resuscitation: definitions, current practice, and knowledge gaps

The History of Fluid Resuscitation for Bleeding

Damage control resuscitation (DCR) is a bundle of care first described by Holcomb et al. that is aimed at reducing death from hemorrhage for patients with severe traumatic bleeding. DCR principles include compressible hemorrhage control; hypotensive resuscitation; rapid surgical control of bleeding; avoidance of the overuse of crystalloids and colloids, prevention or correction of acidosis, hypothermia, and hypocalcaemia; and hemostatic resuscitation (blood-based resuscitation). Remote damage control resuscitation (RDCR) is defined as the prehospital application of DCR concepts. The term RDCR was first published by Gerhardt and has been disseminated by the (Trauma Hemostasis and Oxygenation Research), or THOR Network. The history of DCR and RDCR starts well before the inception of the terms. The concepts behind the principles of DCR and RDCR stretch far back into the past. This chapter provides an outline of this history, but it is limited to the fluid resuscitation aspect of DCR/RDCR.

Fresh Low Titer O Whole Blood Transfusion in the Austere Medical Environment

Massive hemorrhage is an immediate threat to life. The military developed the Tactical Combat Casualty Care guidelines to address the management of acute trauma, including administration of blood products. The guidelines have been expanded to include low titer O whole blood, which is in limited use by the military. This proposal describes how the transfusion of fresh whole blood might be applied to the remote civilian environment. In doing so, this life-saving intervention may be brought to the austere medical environment, allowing critically hemorrhaging patients to survive to reach definitive medical care.

Role of Hemorrhagic Shock in Experimental Polytrauma

Hemorrhagic shock (HS) after tissue trauma increases the complication and mortality rate of polytrauma (PT) patients. Although several murine trauma models have been introduced, there is a lack of knowledge about the exact impact of an additional HS. We hypothesized that HS significantly contributes to organ injury, which can be reliably monitored by detection of specific organ damage markers. Therefore we established a novel clinically relevant PT plus HS model in C57BL/6 mice which were randomly assigned to control, HS, PT, or PT+HS procedure (n = 8 per group). For induction of PT, anesthetized animals received a blunt chest trauma, head injury, femur fracture, and soft tissue injury. HS was induced by pressure-controlled blood drawing (mean arterial blood pressure of 30 mmHg for 60 min) and mice then resuscitated with ionosterile (4 × volume drawn), monitored, and killed for blood and organ harvesting 4 h after injury. After HS and resuscitation, PT+HS mice required earlier and overall more catecholamine support than HS animals to keep their mean arterial blood pressure. HS significantly contributed to the systemic release of interleukin-6 and high mobility group box 1 protein. Furthermore, the histological lung injury score, pulmonary edema, neutrophil influx, and plasma clara cell protein 16 were all significantly enhanced in PT animals in the presence of an additional HS. Although early morphological changes were minor, HS also contributed functionally to remote acute kidney injury but not to early liver damage. Moreover, PT-induced systemic endothelial injury, as determined by plasma syndecan-1 levels, was significantly aggravated by an additional HS. These results indicate that HS adds to the systemic inflammatory reaction early after PT. Within hours after PT, HS seems to aggravate pulmonary damage and to worsen renal and endothelial function which might overall contribute to the development of early multiple organ dysfunction.

The use of whole blood in US military operations in Iraq, Syria, and Afghanistan since the introduction of low-titer Type O whole blood: feasibility, acceptability, challenges

BACKGROUND

Hemorrhage is the leading cause of preventable death in military and civilian traumatic injury. Blood product resuscitation improves survival. Low-titer Type O Whole Blood (LTOWB) was recently re-introduced to the combat theater as a universal resuscitation product for hemorrhagic shock. This study assessed the utilization patterns of LTOWB compared to warm fresh whole blood (WFWB) and blood component therapy (CT) in US Military Operations in Iraq/Syria and Afghanistan known as Operation Inherent Resolve (OIR) and Operation Freedom's Sentinel (OFS) respectively. We hypothesized LTOWB utilization would increase over time given its advantages.

STUDY DESIGN AND METHODS

Using the Theater Medical Data Store, patients receiving blood products between January 2016 and December 2017 were identified. Product utilization ratios (PUR) for LTOWB, WFWB, and CT were compared across Area of Operations (AORs), medical treatment facilities (Role 2 vs. Role 3), and time. PUR was defined as number of blood products transfused/(number of blood products transfused + number of blood products wasted).

RESULTS

The overall PUR for all blood products was 17.4%; the LTOWB PUR was 14.3%. Over the study period, the total number of blood products transfused increased 133%. Although the total whole blood (WB) increased from 2.1% to 6.6% of all products transfused, WFWB use remained at 2% while LTOWB transfusions increased from 0.5% to 4%. Transfusion of LTOWB occurred more in austere Role 2 facilities compared to Role 3 hospitals.

CONCLUSIONS

LTOWB transfusion is feasible in austere, far-forward environments. Further investigation is needed regarding the safety, clinical outcomes, and drivers of LTOWB transfusions.

RePHILL: protocol for a randomised controlled trial of pre-hospital blood product resuscitation for trauma

OBJECTIVES

To describe the 'Resuscitation with Pre-HospItaL bLood products' trial (RePHILL) - a multi-centre randomised controlled trial of pre-hospital blood product (PHBP) administration vs standard care for traumatic haemorrhage.

BACKGROUND

PHBP are increasingly used for pre-hospital trauma resuscitation despite a lack of robust evidence demonstrating superiority over crystalloids. Provision of PHBP carries additional logistical and regulatory implications, and requires a sustainable supply of universal blood components.

METHODS

RePHILL is a multi-centre, two-arm, parallel group, open-label, phase III randomised controlled trial currently underway in the UK. Patients attended by a pre-hospital emergency medical team, with traumatic injury and hypotension (systolic blood pressure <90 mmHg or absent radial pulse) believed to be due to traumatic haemorrhage are eligible. Exclusion criteria include age <16 years, blood product receipt on scene prior to randomisation, Advanced Medical Directive forbidding blood product administration, pregnancy, isolated head injury and prisoners. A total of 490 patients will be recruited in a 1 : 1 ratio to receive either the intervention (up to two units of red blood cells and two units of lyophilised plasma) or the control (up to four boluses of 250 mL 0.9% saline). The primary outcome measure is a composite of failure to achieve lactate clearance of ≥20%/h over the first 2 hours after randomisation and all-cause mortality between recruitment and discharge from the primary receiving facility to non-acute care. Secondary outcomes include pre-hospital time, coagulation indices, in-hospital transfusion requirements and morbidity.

RESULTS

Pilot study recruitment began in December 2016. Approval to proceed to the main trial was received in June 2017. Recruitment is expected to continue until 2020.

CONCLUSIONS

RePHILL will provide high-quality evidence regarding the efficacy and safety of PHBP resuscitation for trauma.

Hemostatic responses to exercise, dehydration, and simulated bleeding in heat-stressed humans

Heat stress followed by an accompanying hemorrhagic challenge may influence hemostasis. We tested the hypothesis that hemostatic responses would be increased by passive heat stress, as well as exercise-induced heat stress, each with accompanying central hypovolemia to simulate a hemorrhagic insult. In aim 1, subjects were exposed to passive heating or normothermic time control, each followed by progressive lower-body negative pressure (LBNP) to presyncope. In aim 2 subjects exercised in hyperthermic environmental conditions, with and without accompanying dehydration, each also followed by progressive LBNP to presyncope. At baseline, pre-LBNP, and post-LBNP (<1, 30, and 60 min), hemostatic activity of venous blood was evaluated by plasma markers of hemostasis and thrombelastography. For aim 1, both hyperthermic and normothermic LBNP (H-LBNP and N-LBNP, respectively) resulted in higher levels of factor V, factor VIII, and von Willebrand factor antigen compared with the time control trial (all P < 0.05), but these responses were temperature independent. Hyperthermia increased fibrinolysis [clot lysis 30 min after the maximal amplitude reflecting clot strength (LY₃₀)] to 5.1% post-LBNP compared with 1.5% (time control) and 2.7% in N-LBNP ( P = 0.05 for main effect). Hyperthermia also potentiated increased platelet counts post-LBNP as follows: 274 K/µl for H-LBNP, 246 K/µl for N-LBNP, and 196 K/µl for time control ( P < 0.05 for the interaction). For aim 2, hydration status associated with exercise in the heat did not affect the hemostatic activity, but fibrinolysis (LY₃₀) was increased to 6-10% when subjects were dehydrated compared with an increase to 2-4% when hydrated ( P = 0.05 for treatment). Central hypovolemia via LBNP is a primary driver of hemostasis compared with hyperthermia and dehydration effects. However, hyperthermia does induce significant thrombocytosis and by itself causes an increase in clot lysis. Dehydration associated with exercise-induced heat stress increases clot lysis but does not affect exercise-activated or subsequent hypovolemia-activated hemostasis in hyperthermic humans. Clinical implications of these findings are that quickly restoring a hemorrhaging hypovolemic trauma patient with cold noncoagulant fluids (crystalloids) can have serious deleterious effects on the body's innate ability to form essential clots, and several factors can increase clot lysis, which should therefore be closely monitored.

Loss of Syndecan-1 Abrogates the Pulmonary Protective Phenotype Induced by Plasma After Hemorrhagic Shock

Syndecan-1 (Sdc1) is considered a biomarker of injury to the endothelial glycocalyx following hemorrhagic shock, with shedding of Sdc1 deleterious. Resuscitation with fresh frozen plasma (FFP) has been correlated with restitution of pulmonary Sdc1 and reduction of lung injury, but the precise contribution of Sdc1 to FFPs protection in the lung remains unclear. Human lung endothelial cells were used to assess the time and dose-dependent effect of FFP on Sdc1 expression and the effect of Sdc1 silencing on in vitro endothelial cell permeability and actin stress fiber formation. Wild-type and Sdc1 mice were subjected to hemorrhagic shock followed by resuscitation with lactated Ringers (LR) or FFP and compared with shock alone and shams. Lungs were harvested after 3 h for analysis of permeability, histology, and inflammation and for measurement of syndecan- 2 and 4 expression. In vitro, FFP enhanced pulmonary endothelial Sdc1 expression in time- and dose-dependent manners and loss of Sdc1 in pulmonary endothelial cells worsened permeability and stress fiber formation by FFP. Loss of Sdc1 in vivo led to equivalency between LR and FFP in restoring pulmonary injury, inflammation, and permeability after shock. Lastly, Sdc1 mice demonstrated a significant increase in pulmonary syndecan 4 expression after hemorrhagic shock and FFP-based resuscitation. Taken together, our findings support a key role for Sdc1 in modulating pulmonary protection by FFP after hemorrhagic shock. Our results also suggest that other members of the syndecan family may at least be contributing to FFP's effects on the endothelium, an area that warrants further investigation.

Computational Model for Hyperfibrinolytic Onset of Acute Traumatic Coagulopathy

The onset of acute traumatic coagulopathy in trauma patients exacerbates hemorrhaging and dramatically increases mortality. The disease is characterized by increased localized bleeding, and the mechanism for its onset is not yet known. We propose that the fibrinolytic response, specifically the release of tissue-plasminogen activator (t-PA), within vessels of different sizes leads to a variable susceptibility to local coagulopathy through hyperfibrinolysis which can explain many of the clinical observations in the early stages from severely injured coagulopathic patients. We use a partial differential equation model to examine the consequences of vessel geometry and extent of injury on fibrinolysis profiles. In addition, we simulate the efficacy of tranexamic acid treatment on coagulopathy initiated through endothelial t-PA release, and are able to reproduce the time-sensitive nature of the efficacy of this treatment as observed in clinical studies.

Prehospital Blood Product Administration Opportunities in Ground Transport ALS EMS – A Descriptive Study

Introduction

Hemorrhage remains the major cause of preventable death after trauma. Recent data suggest that earlier blood product administration may improve outcomes. The purpose of this study was to determine whether opportunities exist for blood product transfusion by ground Emergency Medical Services (EMS).

Methods

This was a single EMS agency retrospective study of ground and helicopter responses from January 1, 2011 through December 31, 2015 for adult trauma patients transported from the scene of injury who met predetermined hemodynamic (HD) parameters for potential transfusion (heart rate [HR]≥120 and/or systolic blood pressure [SBP]≤90).

Results

A total of 7,900 scene trauma ground transports occurred during the study period. Of 420 patients meeting HD criteria for transfusion, 53 (12.6%) had a significant mechanism of injury (MOI). Outcome data were available for 51 patients; 17 received blood products during their emergency department (ED) resuscitation. The percentage of patients receiving blood products based upon HD criteria ranged from 1.0% (HR) to 5.9% (SBP) to 38.1% (HR+SBP). In all, 74 Helicopter EMS (HEMS) transports met HD criteria for blood transfusion, of which, 28 patients received prehospital blood transfusion. Statistically significant total patient care time differences were noted for both the HR and the SBP cohorts, with HEMS having longer time intervals; no statistically significant difference in mean total patient care time was noted in the HR+SBP cohort.

Conclusions

In this study population, HD parameters alone did not predict need for ED blood product administration. Despite longer transport times, only one-third of HEMS patients meeting HD criteria for blood administration received prehospital transfusion. While one-third of ground Advanced Life Support (ALS) transport patients manifesting HD compromise received blood products in the ED, this represented 0.2% of total trauma transports over the study period. Given complex logistical issues involved in prehospital blood product administration, opportunities for ground administration appear limited within the described system.

MixFM, ZielinskiMD, MyersLA, BernsKS, LukeA, StubbsJR, ZietlowSP, JenkinsDH, SztajnkrycerMD. Prehospital blood product administration opportunities in ground transport ALS EMS – a descriptive study. Prehosp Disaster Med. 2018;33(3):230–236.

The Role of Plasma Transfusion in Massive Bleeding: Protecting the Endothelial Glycocalyx?

Massive hemorrhage is a leading cause of death worldwide. During the last decade several retrospective and some prospective clinical studies have suggested a beneficial effect of early plasma-based resuscitation on survival in trauma patients. The underlying mechanisms are unknown but appear to involve the ability of plasma to preserve the endothelial glycocalyx. In this mini-review, we summarize current knowledge on glycocalyx structure and function, and present data describing the impact of hemorrhagic shock and resuscitation fluids on glycocalyx. Animal studies show that hemorrhagic shock leads to glycocalyx shedding, endothelial inflammatory changes, and vascular hyper-permeability. In these animal models, plasma administration preserves glycocalyx integrity and functions better than resuscitation with crystalloids or colloids. In addition, we briefly present data on the possible plasma components responsible for these effects. The endothelial glycocalyx is increasingly recognized as a critical component for the physiological vasculo-endothelial function, which is destroyed in hemorrhagic shock. Interventions for preserving an intact glycocalyx shall improve survival of trauma patients.

Endotheliopathy of Trauma is an on-Scene Phenomenon, and is Associated with Multiple Organ Dysfunction Syndrome: A Prospective Observational Study

BACKGROUND

Trauma patients are vulnerable to coagulopathy and inflammatory dysfunction associated with endotheliopathy of trauma (EoT). In vitro evidence has suggested that tranexamic acid (TXA) may ameliorate endotheliopathy. We aimed to investigate how soon after injury EoT occurs, its association with multiple organ dysfunction syndrome (MODS), and whether TXA ameliorates it.

METHODS

A prospective observational study included 91 trauma patients enrolled within 60 min of injury and 19 healthy controls. Blood was sampled on enrolment and again 4 to 12 h later. ELISAs measured serum concentrations of syndecan-1 and thrombomodulin as biomarkers of EoT. MODS was compared between groups according to biomarker dynamics: persistently abnormal; abnormal to normal; and persistently normal. Timing of EoT was estimated by plotting biomarker data against time, and then fitting generalized additive models. Biomarker dynamics were compared between those who did or did not receive prehospital TXA.

RESULTS

Median age was 38 (interquartile range [IQR] 24-55) years; 78 of 91 were male. Median injury severity score (ISS) was 22 (IQR 12-36). EoT was estimated to occur at 5 to 8 min after injury. There were no significant differences in ISS between those with or without prehospital EoT. Forty-two patients developed MODS; 31 of 42 with persistently abnormal; 8 of 42 with abnormal to normal; and 3 of 42 with persistently normal biomarkers; P < 0.05. There were no significant differences between TXA and non-TXA groups.

CONCLUSIONS

EoT was present at the scene of injury. MODS was more likely when biomarkers of EoT were persistently raised. There were no significant differences between TXA and non-TXA groups. Prehospital interventions aimed at endothelial restoration may represent a clinically meaningful target for prehospital resuscitation.

Lyophilized plasma attenuates vascular permeability, inflammation and lung injury in hemorrhagic shock

In severe trauma and hemorrhage the early and empiric use of fresh frozen plasma (FFP) is associated with decreased morbidity and mortality. However, utilization of FFP comes with the significant burden of shipping and storage of frozen blood products. Dried or lyophilized plasma (LP) can be stored at room temperature, transported easily, reconstituted rapidly with ready availability in remote and austere environments. We have previously demonstrated that FFP mitigates the endothelial injury that ensues after hemorrhagic shock (HS). In the current study, we sought to determine whether LP has similar properties to FFP in its ability to modulate endothelial dysfunction in vitro and in vivo. Single donor LP was compared to single donor FFP using the following measures of endothelial cell (EC) function in vitro: permeability and transendothelial monolayer resistance; adherens junction preservation; and leukocyte-EC adhesion. In vivo, using a model of murine HS, LP and FFP were compared in measures of HS- induced pulmonary vascular inflammation and edema. Both in vitro and in vivo in all measures of EC function, LP demonstrated similar effects to FFP. Both FFP and LP similarly reduced EC permeability, increased transendothelial resistance, decreased leukocyte-EC binding and persevered adherens junctions. In vivo, LP and FFP both comparably reduced pulmonary injury, inflammation and vascular leak. Both FFP and LP have similar potent protective effects on the vascular endothelium in vitro and in lung function in vivo following hemorrhagic shock. These data support the further development of LP as an effective plasma product for human use after trauma and hemorrhagic shock.

Where's the Leak in Vascular Barriers? A Review

Edema is typically presented as a secondary effect from injury, illness, disease, or medication, and its impact on patient wellness is nested within the underlying etiology. Therefore, it is often thought of more as an amplifier to current preexisting conditions. Edema, however, can be an independent risk factor for patient deterioration. Improper management of edema is costly not only to the patient, but also to treatment and care facilities, as mismanagement of edema results in increased lengths of hospital stay. Direct tissue trauma, disease, or inappropriate resuscitation and/or ventilation strategies result in edema formation through physical disruption and chemical messenger-based structural modifications of the microvascular barrier. Derangements in microvascular barrier function limit tissue oxygenation, nutrient flow, and cellular waste removal. Recent studies have sought to elucidate cellular signaling and structural alterations that result in vascular hyperpermeability in a variety of critical care conditions to include hemorrhage, burn trauma, and sepsis. These studies and many others have highlighted how multiple mechanisms alter paracellular and/or transcellular pathways promoting hyperpermeability. Roles for endothelial glycocalyx, extracellular matrix and basement membrane, vesiculo-vacuolar organelles, cellular junction and cytoskeletal proteins, and vascular pericytes have been described, demonstrating the complexity of microvascular barrier regulation. Understanding these basic mechanisms inside and out of microvessels aid in developing better treatment strategies to mitigate the harmful effects of excessive edema formation.

Remote Damage Control Resuscitation in Austere Environments

Hemorrhage is the leading cause of preventable military and civilian trauma death. Damage control resuscitation with concomitant mechanical hemorrhage control has become the preferred in-hospital treatment of hemorrhagic shock. In particular, plasma-based resuscitation with decreased volumes of crystalloids and artificial colloids as part of damage control resuscitation has improved outcomes in the military and civilian sectors. However, translation of these principles and techniques to the prehospital, remote, and austere environments, known as remote damage control resuscitation, is challenging given the resource limitations in these settings. Rapid administration of tranexamic acid and reconstituted freeze-dried (lyophilized) plasma as early as the point of injury are feasible and likely beneficial, but comparative studies in the literature are lacking. Whole blood is likely the best fluid therapy for traumatic hemorrhagic shock, but logistical hurdles need to be addressed. Rapid control of external hemorrhage with hemostatic dressings and extremity tourniquets are proven therapies, but control of noncompressible hemorrhage (ie, torso hemorrhage) remains a significant challenge.

Fluid Resuscitation in Tactical Combat Casualty Care: Yesterday and Today

The prevailing wisdom for the prehospital fluid resuscitation of trauma victims in hemorrhagic shock in 1992 was to administer 2 L of crystalloid solution as rapidly as possible. A review of the fluid resuscitation literature found that this recommendation was not well supported by the evidence at the time. Prehospital fluid resuscitation strategies were reevaluated in the 1993-1996 Tactical Combat Casualty Care (TCCC) research program. This article reviews the advances in prehospital fluid resuscitation as recommended by the original TCCC Guidelines and modified over the following 2 decades. These advances include hypotensive resuscitation, use of prehospital whole blood or blood components when feasible, and use of Hextend or selected crystalloids when logistical considerations make blood or blood component use not feasible.

A Pilot Study of Viscoelastic Monitoring in Pediatric Trauma: Outcomes and Lessons Learned

Background:

Examine the characteristics and outcomes of pediatric trauma patients at risk for coagulopathy following implementation of viscoelastic monitoring.

Materials and Methods:

Injured children, aged <18 years, from September 7, 2014, to December 21, 2015, at risk for trauma-induced coagulopathy were identified from a single, level-1 American College of Surgeons verified pediatric trauma center. Patients were grouped by coagulation assessment: no assessment (NA), conventional coagulation testing alone (CCT), and conventional coagulation testing with rapid thromboelastography (rTEG). Coagulation assessment was provider preference with all monitoring options continuously available. Groups were compared and outcomes were evaluated including blood product utilization, Intensive Care Unit (ICU) utilization, duration of mechanical ventilation, and mortality.

Results:

A total of 155 patients were identified (NA = 78, CCT = 54, and rTEG = 23). There was no difference in age, gender, race, or mechanism. In practice, rTEG patients were more severely injured, more anemic, and received more blood products and crystalloid (P < 0.001). rTEG patients also had increased mortality with fewer ventilator and ICU-free days. Multivariate logistic regression and covariance analysis indicated that while rTEG use was not associated with mortality, it was associated with increased use of blood products, duration of mechanical ventilation, and ICU length of stay.

Conclusions:

Viscoelastic monitoring was infrequently performed, but utilized in more severely injured patients. Well-designed prospective studies in patients at high risk of coagulopathy are needed to evaluate goal-directed hemostatic resuscitation strategies in children.

Cold platelets for trauma-associated bleeding: regulatory approval, accreditation approval, and practice implementation-just the "tip of the iceberg"

BACKGROUND

Laboratory and clinical evidence suggest that cold-stored platelets (CS-PLTs) might be preferable to room temperature platelets (RT-PLTs) for active bleeding. Ease of prehospital use plus potential hemostatic superiority led our facility to pursue approval of CS-PLTs for actively bleeding trauma patients.

STUDY DESIGN AND METHODS

From November 18, 2013, through October 8, 2015, correspondence was exchanged between our facility, the AABB, and the US Food and Drug Administration (FDA). An initial AABB variance request was for 5-day CS-PLTs without agitation. The AABB deferred its decision pending FDA approval to use our platelet (PLT) bags for CS-PLTs. On March 27, 2015, the FDA approved 3-day CS-PLTs without agitation. On October 8, 2015, the AABB approved 3-day CS-PLTs without agitation and without bacterial testing for actively bleeding trauma patients. Our facility's goal is to carry CS-PLTs on air ambulances.

RESULTS

CS-PLTs have been used for trauma patients at our facility since October 2015. As of August 2016, a total of 21 (19.1%) of 119 CS-PLTs have been transfused. The short 3-day storage period combined with the formation of clots in plasma-rich CS-PLTs during storage have been the major causes of a high (80.9%) discard rate.

CONCLUSION

In the future, pathogen-reduced (PR), PLT additive solution (PAS) CS-PLTs seem more practical due to low risks of bacterial contamination and storage-related clotting. This should make longer storage of CS-PLTs feasible (e.g., 10 days or more). With a longer shelf life, PR PAS CS-PLTs could potentially be used in a wider range of patient populations.

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.

Deployed skills training for whole blood collection by a special operations expeditionary surgical team

BACKGROUND

Noncompressible hemorrhage is the leading cause of potentially preventable battlefield death. Combining casualty retrieval from the battlefield and damage control resuscitation (DCR) within the "golden hour" increases survival. However, transfusion requirements may exceed the current blood component stocks held by forward surgical teams. Warm fresh whole blood (WFWB) is an alternative. We report WFWB transfusion training developed by and delivered to a US Golden Hour Offset Surgical Treatment Team and the resulting improvement in confidence with WFWB transfusion.

METHODS

A bespoke instructional package was derived from existing operational clinical guidelines. All Golden Hour Offset Surgical Treatment Team personnel completed initial training, reinforced through ongoing casualty simulations. A record of blood types and donor eligibility was established to facilitate rapid identification of potential WFWB donors. Self-reported confidence in seven aspects of the WFWB transfusion process was assessed before and after training using a five-point Likert scale. Personnel were analyzed by groups consisting of those whose operational role includes WFWB transfusion ("transfusers"), clinical personnel without such responsibilities ("nontransfusers") and nonclinical personnel (other). Comparisons within and between groups were made using appropriate nonparametric tests.

RESULTS

Data were collected from 39 (89%) of 44 training participants: 24 (62%) transfusers, 12 (31%) nontransfusing clinicians, and 3 (8%) other personnel. Transfusers and nontransfusers reported increased comfort with all practical elements of WFWB transfusion. The confidence of other personnel also increased, but (likely due to small numbers) was not statistically significant.

CONCLUSION

WFWB transfusion is an integral part of modern deployed military remote DCR. Our in-theater training program rapidly and reproducibly enhanced the comfort in WFWB transfusion in providers from a range of backgrounds and skill-mixes. This model has the potential to improve both safety and effectiveness of WFWB remote DCR in the far-forward deployed setting.

LEVEL OF EVIDENCE

Therapeutic/care management study, level IV.

Early tranexamic acid administration ameliorates the endotheliopathy of trauma and shock in an in vitro model

BACKGROUND

Systemic vascular endothelial injury is a consequence of trauma (T)/hemorrhagic shock (HS) which results in disturbances of coagulation, inflammation, and endothelial barrier integrity. The effect of T/HS on the endothelium (endotheliopathy of trauma [EoT]) is of intense research interest and may lead to EoT-directed therapies. Administration of tranexamic acid (TXA) in trauma patients is associated with a survival benefit and fewer complications if given early after injury. Mechanisms for this protective effect include the antifibrinolytic and anti-inflammatory effects of TXA. We hypothesized that "early" administration of TXA would abrogate vascular endothelial cell activation and injury after T/HS. This was studied in vitro.

METHODS

Confluent human umbilical vein endothelial cells were exposed to hydrogen peroxide and/or epinephrine to stimulate post-T/HS oxidant exposure and/or sympathoadrenal activation. TXA was added 15 minutes, 60 minutes, or 120 minutes after H2O2 and/or epinephrine challenge. Endothelial cell injury was indexed by cell monolayer permeability, intracellular adhesion molecule expression, soluble thrombomodulin, syndecan release (marker for glycocalyx injury), tissue type plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and angiopoietin-2/angiopoietin-1 ratio (APO-2/APO-1).

RESULTS

Endothelial activation and injury as indexed by permeability, ICAM expression, soluble thrombomodulin were increased by H2O2 and/or epinephrine exposure. Biomarkers of endothelial coagulation profile (tPA/PAI-1) demonstrated a profibrinolytic profile (increased tPA and tPA/PAI-1 ratio) after challenge by H2O2 and/or epinephrine. Vascular "leakiness" as indexed by APO-2/APO-1 ratio was also evident. The most profound effects were noted with H2O2/epinephrine exposure. TXA administration within 60 minutes of H2O2/epinephrine challenge abolished the adverse effects noted on the endothelial-glycocalyx "double barrier." TXA administration after 60 minutes was not protective.

CONCLUSION

Antifibrinolytic and other protective effects of TXA administration on endothelial injury are time-dependent. This study supports the concept that the clinical efficacy of TXA administration requires "early administration."

Damage control surgery in weightlessness: A comparative study of simulated torso hemorrhage control comparing terrestrial and weightless conditions

BACKGROUND

Torso bleeding remains the most preventable cause of post-traumatic death worldwide. Remote damage control resuscitation (RDCR) endeavours to rescue the most catastrophically injured, but has not focused on prehospital surgical torso hemorrhage control (HC). We examined the logistics and metrics of intraperitoneal packing in weightlessness in Parabolic flight (0g) compared to terrestrial gravity (1g) as an extreme example of surgical RDCR.

METHODS

A surgical simulator was customized with high-fidelity intraperitoneal anatomy, a "blood" pump and flowmeter. A standardized HC task was to explore the simulator, identify "bleeding" from a previously unknown liver injury perfused at 80 mm Hg, and pack to gain hemostasis. Ten surgeons performed RDCR laparotomies onboard a research aircraft, first in 1g followed by 0g. The standardized laparotomy was sectioned into 20-second segments to conduct and facilitate parabolic flight comparisons, with "blood" pumped only during these time segments. A maximum of 12 segments permitted for each laparotomy.

RESULTS

All 10 surgeons successfully performed HC in both 1g and 0g. There was no difference in blood loss between 1g and 0g (p = 0.161) or during observation following HC (p = 0.944). Compared to 1g, identification of bleeding in 0g incurred less "blood" loss (p = 0.032). Overall surgeons rated their personal performance and relative difficulty of surgery in 0g as "harder" (median Likert, 2/5). However, conducting all phases of HC were rated equivalent between 1g and 0g (median Likert, 3/5), except for instrument control (rated slightly harder, 2.75/5).

CONCLUSION

Performing laparotomies with packing of a simulated torso hemorrhage in a high-fidelity surgical simulator was feasible onboard a research aircraft in both normal and weightless conditions. Despite being subjectively "harder," most phases of operative intervention were rated equivalently, with no statistical difference in "blood" loss in weightlessness. Direct operative control of torso hemorrhage is theoretically possible in extreme environments if logistics are provided.

Cellular therapies in trauma and critical care medicine: Looking towards the future

Shibani Pati and Todd Rasmussen summarize progress in preclinical research on cellular therapeutics for traumatic injury and its sequelae and discuss prospects for clinical translation.

Multicenter observational prehospital resuscitation on helicopter study

BACKGROUND

Earlier use of in-hospital plasma, platelets, and red blood cells (RBCs) has improved survival in trauma patients with severe hemorrhage. Retrospective studies have associated improved early survival with prehospital blood product transfusion (PHT). We hypothesized that PHT of plasma and/or RBCs would result in improved survival after injury in patients transported by helicopter.

METHODS

Adult trauma patients transported by helicopter from the scene to nine Level 1 trauma centers were prospectively observed from January to November 2015. Five helicopter systems had plasma and/or RBCs, whereas the other four helicopter systems used only crystalloid resuscitation. All patients meeting predetermined high-risk criteria were analyzed. Patients receiving PHT were compared with patients not receiving PHT. Our primary analysis compared mortality at 3 hours, 24 hours, and 30 days, using logistic regression to adjust for confounders and site heterogeneity to model patients who were matched on propensity scores.

RESULTS

Twenty-five thousand one hundred eighteen trauma patients were admitted, 2,341 (9%) were transported by helicopter, of which 1,058 (45%) met the highest-risk criteria. Five hundred eighty-five of 1,058 patients were flown on helicopters carrying blood products. In the systems with blood available, prehospital median systolic blood pressure (125 vs 128) and Glasgow Coma Scale (7 vs 14) was significantly lower, whereas median Injury Severity Score was significantly higher (21 vs 14). Unadjusted mortality was significantly higher in the systems with blood products available, at 3 hours (8.4% vs 3.6%), 24 hours (12.6% vs 8.9%), and 30 days (19.3% vs 13.3%). Twenty-four percent of eligible patients received a PHT. A median of 1 unit of RBCs and plasma were transfused prehospital. Of patients receiving PHT, 24% received only plasma, 7% received only RBCs, and 69% received both. In the propensity score matching analysis (n = 109), PHT was not significantly associated with mortality at any time point, although only 10% of the high-risk sample were able to be matched.

CONCLUSION

Because of the unexpected imbalance in systolic blood pressure, Glasgow Coma Scale, and Injury Severity Score between systems with and without blood products on helicopters, matching was limited, and the results of this study are inconclusive. With few units transfused to each patient and small outcome differences between groups, it is likely large, multicenter, randomized studies will be required to detect survival differences in this important population.

LEVEL OF EVIDENCE

Level II.

The pragmatic randomized optimal platelet and plasma ratios trial: what does it mean for remote damage control resuscitation?

BACKGROUND

Implications from the pragmatic, randomize, optimal platelet and plasma ratios (PROPPR) trial are critical for remote damage control resuscitation (DCR). Utilizing DCR principals in remote settings can combat early mortality from hemorrhage. Identifying the appropriate transfusion strategy is mandatory prior to adopting prehospital hemostatic resuscitation strategies.

STUDY DESIGN AND METHODS

The PROPPR study was examined in relation to the following questions: 1) Why is it important to have blood products in the prehospital setting?; 2) Which products should be investigated for prehospital hemostatic resuscitation?; 3) What is the appropriate ratio of blood product transfusion?; and 4) What are the appropriate indications for hemostatic resuscitation?

RESULTS

PROPPR demonstrates that early and balanced blood product transfusion ratios reduced mortality in all patients at 3 hours and death from exsanguination at 24 hours (p = 0.03). The median time to death from exsanguination was 2.3 hours, highlighting the need for point-of-injury DCR capabilities. A 1:1:1 transfusion ratio of plasma:platelets:packed red blood cells increased the percentage of patients achieving anatomic hemostasis (p = 0.006). PROPPR used the assessment of blood consumption score to identify patients likely to require ongoing hemostatic resuscitation. The critical administration threshold predicted patient mortality and identified patients likely to require ongoing hemostatic resuscitation.

CONCLUSION

A balanced resuscitation strategy demonstrates an early survival benefit, decreased death from exsanguination at 24 hours and a greater likelihood of achieving hemostasis in critically injured patients receiving a 1:1:1 ratio of plasma:platelets:PRBCs. This finding highlights the need to import DCR principals to remote locations.

Coagulation factor concentrate-based therapy for remote damage control resuscitation (RDCR): a reasonable alternative?

The concept of remote damage control resuscitation (RDCR) is still in its infancy and there is significant work to be done to improve outcomes for patients with life-threatening bleeding secondary to injury. The prehospital phase of resuscitation is critical and if shock and coagulopathy can be rapidly minimized before hospital admission this will very likely reduce morbidity and mortality. The optimum transfusion strategy for these patients is still highly debated and the potential implications of the recently published pragmatic, randomize, optimal platelet, and plasma ratios trial (PROPPR) for RDCR have been reviewed. Identifying the appropriate transfusion strategy is mandatory before adopting prehospital hemostatic resuscitation strategies. An alternative approach is based on the early administration of coagulation factor concentrates combined with the antifibrinolytic tranexamic acid (TXA). The three major components to this approach in the context of RDCR target the following steps to achieve hemostasis: 1) stop (hyper)fibrinolysis; 2) support clot formation; and 3) increase thrombin generation. Strong evidence exists for the use of TXA. The data from the prospective fibrinogen in trauma induced coagulopathy (FIinTIC) study will inform on the prehospital use of fibrinogen in bleeding trauma patients. Deficits in thrombin generation may be addressed by the administration of prothrombin complex concentrates. Handheld point-of-care devices may be able to support and guide the prehospital and remote use of intravenous hemostatic agents including coagulation factor concentrates along with clinical presentation, assessment, and the extent of bleeding. Combinations may even be more effective for bleeding control. More studies are urgently needed.

NATO Blood Panel perspectives on changes to military prehospital resuscitation policies: current and future practice

The North Atlantic Treaty Organization (NATO) Blood Panel exists to promote interoperability of transfusion practice between NATO partners. However, it has served as an important forum for the development of prehospital transfusion and transfusion in the austere environment. There are synergies with the trauma hemostasis and oxygen research community especially in the areas of innovation and research. Four presentations are summarized together with a review of some scientific principles. The past decade has already seen significant changes in early transfusion support. Sometimes practice has preceded the evidence and has stretched regulatory and logistic constraints. Ethical and philosophical issues are also important and require us to question "should we" and not just "could we." The challenge for the combined communities is to continue to optimize transfusion support underpinned by evidence-based excellence.

Surgical adjuncts to noncompressible torso hemorrhage as tools for patient blood management

Despite the tremendous advances and successes in the care of combat casualties over the past 15 years of war, noncompressible torso hemorrhage (NCTH) remains the most likely source of potentially preventable death (approx. 25%) on the battlefield. This is also likely true for civilian victims of blunt and penetrating trauma. Various devices and therapeutic interventions have been, and are being, developed in an attempt to reduce morbidity and mortality for patients with NCTH. Examples include the use of prehospital blood and blood products, tranexamic acid, specially designed tourniquets for junctional hemorrhage control, retrograde endovascular balloon occlusion of the aorta, intracavity foam, expandable hemostatic sponges, and intravascular nanoparticles to suspended animation. Although each of these modalities offer the potential to staunch uncontrolled hemorrhage until an injured patient is able to reach definitive surgical care, further research and advances must be made to further reduce trauma morbidity and mortality and to identify those technologies and modalities that are best suited to rapid movement to the front lines of combat casualty care as well as to emergency medical personnel dealing with civilian trauma victims. The surgical adjuncts for NCTH discussed may all be considered as potential tools for patient blood management programs. If effective they offer the possibility of reduce hemorrhage and blood product exposure and improved patient outcomes.

Whole blood transfusion closest to the point-of-injury during French remote military operations

To improve the survival of combat casualties, interest in the earliest resort to whole blood (WB) transfusion on the battlefield has been emphasized. Providing volume, coagulation factors, plasma, and oxygenation capacity, WB appears actually as an ideal product severe trauma management. Whole blood can be collected in advance and stored for subsequent use, or can be drawn directly on the battlefield, once a soldier is wounded, from an uninjured companion and immediately transfused.Such concepts require a great control of risks at each step, especially regarding ABO mismatches, and transfusion-transmitted diseases. We present here the "warm and fresh" WB field transfusion program implemented among the French armed forces. We focus on the followed strategies to make it applicable on the battlefield, even during special operations and remote settings, and safe for recipients as well as for donors.

Lack of species-specific difference in pulmonary function when using mouse versus human plasma in a mouse model of hemorrhagic shock

BACKGROUND

Clinical studies have demonstrated that the early and empiric use of plasma improves survival after hemorrhagic shock. We have demonstrated in rodent models of hemorrhagic shock that resuscitation with plasma is protective to the lungs compared with lactated Ringer's solution. As our long-term objective is to determine the molecular mechanisms that modulate plasma's protective effects in injured bleeding patients, we have used human plasma in a mouse model of hemorrhagic shock. The goal of the current experiments is to determine if there are significant adverse effects on lung injury when using human versus mouse plasma in an established murine model of hemorrhagic shock and laparotomy.

METHODS

Mice underwent laparotomy and 90 minutes of hemorrhagic shock to a mean arterial pressure (MAP) of 35 ± 5 mm Hg followed by resuscitation at 1× shed blood using either mouse fresh frozen plasma (FFP), human FFP, or human lyophilized plasma. Mean arterial pressure was recorded during shock and for the first 30 minutes of resuscitation. After 3 hours, animals were killed, and lungs collected for analysis.

RESULTS

There was a significant increase in early MAP when mouse FFP was used to resuscitate animals compared with human FFP or human lyophilized plasma. However, despite these differences, analysis of the mouse lungs revealed no significant differences in pulmonary histopathology, lung permeability, or lung edema between all three plasma groups. Analysis of neutrophil infiltration in the lungs revealed that mouse FFP decreased neutrophil influx as measured by neutrophil staining; however, myeloperoxidase immunostaining revealed no significant differences in between groups.

CONCLUSION

The study of human plasma in a mouse model of hemorrhagic shock is feasible but does reveal some differences compared with mouse plasma-based resuscitation in physiologic measures such as MAP postresuscitation. Measures of end organ function such as lung injury appear to be comparable in this acute model of hemorrhagic shock and resuscitation.

Abbreviated closure for remote damage control laparotomy in extreme environments: A randomized trial of sutures versus wound clamps comparing terrestrial and weightless conditions

INTRODUCTION

Far-Forward Damage Control Laparotomies (DCLs) might provide direct-compression of visceral hemorrhage, however, suturing is a limiting factor, especially for non-physicians. We thus compared abbreviated skin closures comparing skin-suture (SS) versus wound-clamp (WC), on-board a research aircraft in weightlessness (0g) and normal gravity (1g).

METHODS

Surgeons conducted DCLs on a surgical-simulator; onboard the hangered-aircraft (1g), or during parabolic flight (0g), randomized to either WC or SS.

RESULTS

Ten surgeons participated. Two (40%) surgeons randomized to suture in 0g were incapacitated with motion-sickness, and none were able to close in either 1 or 0g. With WC, two completely closed in 1g as did three in 0g, despite having longer incisions (p = 0.016). Overall skin-closure with WC was significantly greater in both 1g (p = 0.016) and 0g (p = 0.008).

CONCLUSIONS

WC was more effective in 1g and particularly 0g. Future studies should address the utility of abbreviated WC abdominal closure to facilitate potential Far-Forward DCL.

TRIAL REGISTRATION

ID ISRCTN/77929274.

Tranexamic Acid Update in Trauma

Following results from the CRASH-2 trial, tranexamic acid (TXA) gained considerable interest for the treatment of hemorrhage in trauma patients. Although TXA is effective at reducing mortality in patients presenting within 3 hours of injury, optimal dosing, timing of administration, mechanism, and pharmacokinetics require further elucidation. The concept of fibrinolysis shutdown in hemorrhagic trauma patients has prompted discussion of real-time viscoelastic testing and its potential role for appropriate patient selection. The results of ongoing clinical trials will help establish high-quality evidence for optimal incorporation of TXA in mature trauma networks in the United States and abroad.

Refrigerated platelets stored in whole blood up to 5 days adhere to thrombi formed during hemorrhagic hypotension in rats

Essentials In vivo function of platelets stored at various conditions was studied in normo- and hypotension. Refrigerated platelets stored up to 5 days performed as well as those stored at room temperature. Platelet adhesion and thrombus formation were higher in ruptured vessels of hemorrhaged animals. In vivo data suggest that refrigerated platelets are hemostatically effective during hypotension.

SUMMARY

Background There is renewed interest in the therapeutic use of cold-stored platelets for bleeding patients. However, critical information is absent or partially available in vitro. Therefore, thrombus formation and platelet adhesion were studied in vivo, in situ, using bleeding and thrombosis models in instrumented rats, and confocal intravital videomicroscopy. Objectives We tested the hypothesis that refrigerated (4 °C) platelets (stored for 24 h or 5 days) participated in thrombus formation as well as platelets stored at room temperature (RT, 22 °C). This hypothesis was tested in normovolemia and hemorrhagic hypotension. Methods & Results After fluorescently-labeled platelet infusion, endothelial injury and vessel rupture were laser-induced in cremaster microvessels and platelet adhesion in > 230 developing thrombi was evaluated. Blood samples were collected for biochemistry and coagulation assays while multiple systemic physiologic parameters were recorded. Hemorrhagic hypotension study animals were subjected to 40% hemorrhage, leading to hypotension and hemodilution, during in vivo platelet adhesion assessments. The fluorescence intensity associated with labeled platelet adherence provided a quantitative index of adhesion. Cold-stored platelets performed as well as those stored at RT in normovolemic animals. During hypotension, cold-stored platelets still performed as well as RT-stored platelets, whereas platelet adhesion and thrombus formation were increased relative to normovolemic animals, in bleeding model experiments. Conclusions We found the methodology suitable for evaluating platelet function in vivo after different storage conditions in fully monitored animals. Refrigerated platelets (stored up to 5 days) participated as well as RT-stored platelets in thrombi formed after hemorrhage, suggesting that refrigerated platelets are effective during hypotensive situations.

The effects of 22°C and 4°C storage of platelets on vascular endothelial integrity and function

BACKGROUND

Although a majority of the studies conducted to date on platelet (PLT) storage have been focused on PLT hemostatic function, the effects of 4°C PLTs on regulation of endothelial barrier permeability are still not known. In this study, we compared the effects of room temperature (22°C) stored and (4°C) stored PLTs on the regulation of vascular endothelial cell (EC) permeability in vitro and in vivo.

STUDY DESIGN AND METHODS

Day 1, Day 5, and Day 7 leukoreduced apheresis PLTs stored at 4 or 22°C were studied in vitro and in vivo. In vitro, PLT effects on EC permeability and barrier function, adhesion, and impedance aggregometry were investigated. In vivo, using a mouse model of vascular leak, attenuation of vascular leak and circulating PLT numbers were measured.

RESULTS

Treatment of EC monolayers with Day 5 or Day 7 PLTs, stored at both 22°C and 4°C, resulted in similar decreases in EC permeability on average. However, analysis of individual samples revealed significant variation that was donor dependent. Additional in vitro measurements revealed a decrease in inflammatory mediators, nonspecific PLT-endothelial aggregation and attenuated loss of aggregation over time to TRAP, ASPI, ADP, and collagen with 4°C storage. In mice, while 22°C and 4°C PLTs both demonstrated significant protection against vascular endothelial growth factor A (VEGF-A)-induced vascular leak 22°C PLTs exhibited increased protection compared to 4°C PLTs. Systemic circulating levels of 4°C PLTs were decreased compared to 22°C PLTs.

CONCLUSIONS

In vitro, 4°C-stored PLTs exhibit a greater capacity to inhibit EC permeability than 22°C-stored PLTs. In vivo, 22°C PLTs provide superior control of vascular leak induced by VEGF-A. This discrepancy may be due to increased clearance of 4°C PLTs from the systemic circulation.

Platelets regulate vascular endothelial stability: assessing the storage lesion and donor variability of apheresis platelets

BACKGROUND

In current blood banking practices, platelets (PLTs) are stored in plasma at 22°C, with gentle agitation for up to 5 days. To date, the effects of storage and donor variability on PLT regulation of vascular integrity are not known.

STUDY DESIGN AND METHODS

In this study, we examined the donor variability of leukoreduced fresh (Day 1) or stored (Day 5) PLTs on vascular endothelial barrier function in vitro and in vivo. In vitro, PLT effects on endothelial cell (EC) monolayer permeability were assessed by analyzing transendothelial electrical resistances (TEER). PLT aggregation, a measure of hemostatic potential, was analyzed by impedance aggregometry. In vivo, PLTs were investigated in a vascular endothelial growth factor A (VEGF-A)-induced vascular permeability model in NSG mice, and PLT circulation was measured by flow cytometry.

RESULTS

Treatment of endothelial monolayers with fresh Day 1 PLTs resulted in an increase in EC barrier resistance and decreased permeability in a dose-dependent manner. Subsequent treatment of EC monolayers with Day 5 PLTs demonstrated diminished vasculoprotective effects. Donor variability was noted in all measures of PLT function. Day 1 PLT donors were more variable in their effects on TEER than Day 5 PLTs. In mice, while all PLTs regardless of storage time demonstrated significant protection against VEGF-A-induced vascular leakage, Day 5 PLTs exhibited reduced protection when compared to Day 1 PLTs. Day 1 PLTs demonstrated significant donor variability against VEGF-A-challenged vascular leakage in vivo. Systemic circulating levels of Day 1 PLTs were higher than those of Day 5 PLTs

CONCLUSIONS

In vitro and in vivo, Day 1 PLTs are protective in measures of vascular endothelial permeability. Donor variability is most prominent in Day 1 PLTs. A decrease in the protective effects is found with storage of the PLT units between Day 1 and Day 5 at 22°C, thereby suggesting that Day 5 PLTs are diminished in their ability to attenuate vascular endothelial permeability.

Plasma-Mediated Gut Protection After Hemorrhagic Shock is Lessened in Syndecan-1-/- Mice

We have shown in a rodent model of hemorrhagic shock (HS) that fresh frozen plasma (FFP) reduces lung inflammation and injury that are correlated with restitution of syndecan-1. As the gut is believed to contribute to distant organ injury and inflammation after shock, the current study sought to determine if the protective effects of plasma would extend to the gut and to elucidate the contribution of syndecan-1 to this protective effect. We also examined the potential role of TNFα, and a disintegrin and metalloproteinase (ADAM)-17, both intestinal sheddases of syndecan-1. Wild-type (WT) and syndecan-1 (KO) mice were subjected to HS followed by resuscitation with lactated Ringer's (LR) or FFP and compared with shock alone and shams. Small bowel and blood were obtained after 3  h for analysis of mucosal injury and inflammation and TNFα and ADAM-17 protein expression and activity. After HS, gut injury and inflammation were significantly increased compared with shams. Resuscitation with LR decreased both injury and inflammation that were further lessened by FFP. KO mice displayed worsened gut injury and inflammation after HS compared with WT mice, and LR and FFP equivalently inhibited injury and inflammation. Both systemic and intestinal TNFα and ADAM-17 followed similar trends, with increases after HS, reduction by LR, and a further decrease by FFP in WT but not KO mice. In conclusion, FFP decreased gut injury and inflammation after hemorrhagic shock, an effect that was abrogated in syndecan-1 mice. Plasma also decreased TNFα and ADAM-17, representing a potential mechanistic link to its protection via syndecan-1.

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.

Clot Formation Is Associated With Fibrinogen and Platelet Forces in a Cohort of Severely Injured Emergency Department Trauma Patients

INTRODUCTION

Anticoagulation, fibrinogen consumption, fibrinolytic activation, and platelet dysfunction all interact to produce different clot formation responses after trauma. However, the relative contributions of these coagulation components to overall clot formation remain poorly defined. We examined for sources of heterogeneity in clot formation responses after trauma.

METHODS

Blood was sampled in the emergency department from patients meeting trauma team activation criteria at an urban trauma center. Plasma prothrombin time of 18 s or longer was used to define traumatic coagulopathy. Mean kaolin-activated thrombelastography (TEG) parameters were calculated and tested for heterogeneity using analysis of means. Discriminant analysis and forward stepwise variable selection with linear regression were used to determine if prothrombin time, fibrinogen, platelet contractile force (PCF), and D-dimer concentration, representing key mechanistic components of coagulopathy, each contribute to heterogeneous TEG responses after trauma.

RESULTS

Of 95 subjects, 16% met criteria for coagulopathy. Coagulopathic subjects were more severely injured with greater shock and received more blood products in the first 8 h compared with noncoagulopathic subjects. Mean (SD) TEG maximal amplitude (MA) was significantly decreased in the coagulopathic group (57.5 [SD, 4.7] mm vs. 62.7 [SD, 4.7], t test P < 0.001). The MA also exceeded the ANOM predicted upper decision limit for the noncoagulopathic group and the lower decision limit for the coagulopathic group at α = 0.05, suggesting significant heterogeneity from the overall cohort mean. Fibrinogen and PCF best discriminated TEG MA using discriminant analysis. Fibrinogen, PCF, and D-dimer were primary covariates for TEG MA using regression analysis.

CONCLUSIONS

Heterogeneity in TEG-based clot formation in emergency department trauma patients was linked to changes in MA. Individual parameters representing fibrin polymerization, PCFs, and fibrinolysis were primarily associated with TEG MA after trauma and should be the focus of early hemostatic therapies.