Remote Damage Control Resuscitation in Austere Environments

Preparing Future Military Medical Officers to Conduct Emergency Fresh Whole Blood Transfusions in Austere Environments: A Novel Training Curriculum

INTRODUCTION

Providing resilient Damage Control Resuscitation capabilities as close to the point of injury as possible is paramount to reducing mortality and improving patient outcomes for our nation's warfighters. Emergency Fresh Whole Blood Transfusions (EFWBT) play a critical role in supporting this capability, especially in future large-scale combat operations against peer adversaries with expected large patient volumes, restrictive operating environments, and unreliable logistical supply lines. Although there are service-specific training programs for whole blood transfusion, there is currently no dedicated EFWBT training for future military medical officers. To address this gap, we developed, implemented, and evaluated a training program to enhance EFWBT proficiency in third-year military medical students at the F. Edward Hebert School of Medicine at the USU.

MATERIALS AND METHODS

After reviewing both the 75th Ranger Regiment Ranger O-Low Titer program and the Marine Corps' Valkyrie program, along with the relevant Joint Trauma System Clinical Practice Guidelines, we created a streamlined and abbreviated training curriculum. The training consisted of both online preparatory materials as well as a 2-hour in-person training that included didactic and experiential learning components. Participants were 165 active duty third-year medical students at USU. Participants were assessed using a pre- and post-assessment self-reported questionnaire on their confidence in the practical application and administrative oversight requirements of an EFWBT program. Participants' performance was also assessed using a pre/post knowledge assessment consisting of 10 multiple choice questions identified as critical to understanding of the academic principles of EFWBT along with the baseline questionnaire.

RESULTS

Differences in the mean scores of the pre- and post-assessment self-reported questionnaire (increased from 2.32 to 3.95) were statistically significant (P < .001). Similarly, there was a statistically significant improvement in student test scores, with the mean score increasing by approximately 3 points or 30%. There was no significant difference in student confidence assessment or test scores based on branch of service. Students who had previously deployed did not show a statistically significant difference in scores compared to students who had not previously deployed.

CONCLUSIONS

Our results suggest that the implementation of streamlined EFWBT training into the undergraduate medical education of future military medical officers offers an efficient way to improve their baseline proficiency in EFWBTs. Future research is needed to assess the impact of this training on real-world applications in forward-deployed environments.

A Novel Approach to Noncompressible Torso Hemorrhage Using a Silicone-Based Polymer Universal Combat Matrix

INTRODUCTION

Battlefield trauma necessitates prompt hemostatic intervention to mitigate fatalities resulting from critical blood loss. Insights from Operation Enduring Freedom and Operation Iraqi Freedom emphasize the limitations of conventional methods, such as tourniquets, especially in noncompressible torso hemorrhage. Despite advancements in hemostatic agents, the evolving dynamics of multidomain operations necessitate novel, lightweight strategies for hemorrhage control. This study investigates the Silicone-Based Polymer (SBP) Universal Combat Matrix (UCM) by SiOxMed, a multimodal matrix exhibiting efficacy in lethal hemorrhage models. The study evaluates UCM's multiday hemostatic capabilities in a noncompressible torso hemorrhage model, offering pivotal insights for potential deployment in battlefield trauma.

MATERIALS AND METHODS

This research was performed under Institutional Animal Care and Use Committee approval and was designed to replicate austere conditions in an off-site enclosed facility. Yorkshire Hampshire swine underwent baseline assessments and anesthesia induction (n = 3). A Grade IV liver injury was made by incising X-shaped lesions, each measuring 4 cm × 2.5 cm, into the diaphragmatic surface of the left and right middle lobes using a scalpel blade, resulting in a lesion region of approximately 3 cm × 6 cm × 3 cm, followed by 30 seconds of uncontrolled bleeding. The injuries were then treated with SBP. Intensive care unit monitoring for 1 hour ensured sustained hemostasis, followed by 48 hours of postanesthesia monitoring and then a return to the operating table to visualize sustained hemostasis. Posteuthanasia, liver tissue underwent histological assessments to evaluate the hemorrhagic interface and liver tissue reactivity.

RESULTS

The average time to hemostatic control was 247.3 ± 71.3 seconds. Stable heart rate (81.3 ± 10.0) and respiratory rate (31.7 ± 16.5) were maintained during intensive care unit monitoring. All swine survived the 1-hour anesthesia monitoring period and the subsequent 48-hour monitoring (average survival time, 48.0 hours ± 0.0, n = 3). Visualization of the abdominal cavity at 48 hours revealed no hemorrhage. Histological assessment demonstrated aligned red blood cells and stratified layers of fibrin at the hemorrhagic interface. Masson's Trichrome analysis demonstrated a reactive and regenerative scenario 48 hours postinjury, with a collagen membrane demarcating uninjured and exposed liver regions, along with a comprehensive stromal response.

CONCLUSIONS

In conclusion, our investigation into the SBP UCM hemostatic efficacy in a grade IV liver laceration model demonstrates its rapid and reliable action in controlling bleeding, showcasing practicality with an average mass of 4.0 ± 1.0 g. Silicone-Based Polymer sustained hemostasis without adverse physiological effects, as evidenced by stable parameters and the survival of all swine during and after anesthesia. Macroscopic examination at 48 hours revealed durable adherence with no indications of hemorrhage. Histological evaluations highlighted SBP's role in stable clot formation, fibrinogenesis, and tissue regeneration, indicating its potential as a multimodal wound dressing. Although promising, the study has limitations, emphasizing the need for future research with larger samples and controls. This work sets the stage for exploring SBP's clinical implications, particularly in scenarios where lightweight, multimodal technologies are crucial for addressing traumatic injuries and enhancing military medical capabilities.

Early Cold Stored Platelet Transfusion Following Severe Injury: A Randomized Clinical Trial

OBJECTIVE

To determine the feasibility, efficacy, and safety of early cold stored platelet transfusion compared with standard care resuscitation in patients with hemorrhagic shock.

BACKGROUND

Data demonstrating the safety and efficacy of early cold stored platelet transfusion are lacking following severe injury.

METHODS

A phase 2, multicenter, randomized, open label, clinical trial was performed at 5 US trauma centers. Injured patients at risk of large volume blood transfusion and the need for hemorrhage control procedures were enrolled and randomized. The intervention was the early transfusion of a single apheresis cold stored platelet unit, stored for up to 14 days versus standard care resuscitation. The primary outcome was feasibility and the principal clinical outcome for efficacy and safety was 24-hour mortality.

RESULTS

Mortality at 24 hours was 5.9% in patients who were randomized to early cold stored platelet transfusion compared with 10.2% in the standard care arm (difference, -4.3%; 95% CI, -12.8% to 3.5%; P =0.26). No significant differences were found for any of the prespecified ancillary outcomes. Rates of arterial and/or venous thromboembolism and adverse events did not differ across treatment groups.

CONCLUSIONS AND RELEVANCE

In severely injured patients, early cold stored platelet transfusion is feasible, safe and did not result in a significant lower rate of 24-hour mortality. Early cold stored platelet transfusion did not result in a higher incidence of arterial and/or venous thrombotic complications or adverse events. The storage age of the cold stored platelet product was not associated with significant outcome differences.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04667468.

Dried Plasma for Major Trauma: Past, Present, and Future

Uncontrollable bleeding is recognized as the leading cause of preventable death among trauma patients. Early transfusion of blood products, especially plasma replacing crystalloid and colloid solutions, has been shown to increase survival of severely injured patients. However, the requirements for cold storage and thawing processes prior to transfusion present significant logistical challenges in prehospital and remote areas, resulting in a considerable delay in receiving thawed or liquid plasma, even in hospitals. In contrast, freeze- or spray-dried plasma, which can be massively produced, stockpiled, and stored at room temperature, is easily carried and can be reconstituted for transfusion in minutes, provides a promising alternative. Drawn from history, this paper provides a review of different forms of dried plasma with a focus on in vitro characterization of hemostatic properties, to assess the effects of the drying process, storage conditions in dry form and after reconstitution, their distinct safety and/or efficacy profiles currently in different phases of development, and to discuss the current expectations of these products in the context of recent preclinical and clinical trials. Future research directions are presented as well.

Predictors of Short-Term Trauma Laparotomy Outcomes in an Integrated Military-Civilian Health System: A 23-Year Retrospective Cohort Study

Background: Trauma laparotomy (TL) remains a cornerstone of trauma care. We aimed to investigate prehospital measures associated with in-hospital mortality among casualties subsequently undergoing TLs in civilian hospitals. Methods: This retrospective cohort study cross-referenced the prehospital and hospitalization data of casualties treated by Israel Defense Forces-Medical Corps teams who later underwent TLs in civilian hospitals between 1997 and 2020. Results: Overall, we identified 217 casualties treated by IDF-MC teams that subsequently underwent a TL, with a mortality rate of 15.2% (33/217). The main mechanism of injury was documented as penetrating for 121/217 (55.8%). The median heart rate and blood pressure were within the normal limit for the entire cohort, with a low blood pressure predicting mortality (65 vs. 127, p < 0.001). In a multivariate analysis, prehospital endotracheal intubation (ETI), emergency department Glasgow coma scores of 3-8, and the need for a thoracotomy or bowel-related procedures were significantly associated with mortality (OR 6.8, p < 0.001, OR = 48.5, p < 0.001, and OR = 4.61, p = 0.002, respectively). Conclusions: Prehospital interventions introduced throughout the study period did not lead to an improvement in survival. Survival was negatively influenced by prehospital ETI, reinforcing previous observations of the potential deleterious effects of definitive airways on hemorrhaging trauma casualties. While a low blood pressure was a predictor of mortality, the median systolic blood pressure for even the sickest patients (ISS > 16) was within normal limits, highlighting the challenges in triage and risk stratification for trauma casualties.

Ultra-forward surgical support for special operations forces. Conception, development and certification of the French Special Operations Surgical Team (SOST) airborne capability

When special operations forces (SOF) are in action, a surgical team (SOST) is usually ground deployed as close as possible to the combat area, to try and provide surgical support within the golden hour. The French SOST is composed of 6 people: 2 surgeons, 1 scrub nurse, 1 anaesthetist, 1 anesthetic nurse and 1 SOF paramedic. It can be deployed in 45 min under a tent or in a building. However, some tactical situations prevent the ground deployment. A solution is to deploy the SOST in a tactical unprepared aircraft hold, to make it possible to offer DCS, to treat non-compressible exsanguinating trauma, without any ground logistical footprint. This article describes the stages of the design, development and certification process of the airborne SOST capability. The authors report the modifications and adaptations of the equipment and the surgical paradigms which make it possible to solve the constraints linked to the aeronautical and combat environment. Study type/level of evidence Care management Level of Evidence IV.

Investigating the variability in pressure-volume relationships during hemorrhage and aortic occlusion

Introduction

The pressure-volume (P-V) relationships of the left ventricle are the classical benchmark for studying cardiac mechanics and pumping function. Perturbations in the P-V relationship (or P-V loop) can be informative and guide the management of heart failure, hypovolemia, and aortic occlusion. Traditionally, P-V loop analyses have been limited to a single-beat P-V loop or an average of consecutive P-V loops (e.g., 10 cardiac cycles). While there are several algorithms to obtain single-beat estimations of the end-systolic and end-diastolic pressure-volume relations (i.e., ESPVR and EDPVR, respectively), there remains a need to better evaluate the variations in P-V relationships longitudinally over time. This is particularly important when studying acute and transient hemodynamic and cardiac events, such as active hemorrhage or aortic occlusion. In this study, we aim to investigate the variability in P-V relationships during hemorrhagic shock and aortic occlusion, by leveraging on a previously published porcine hemorrhage model.

Methods

Briefly, swine were instrumented with a P-V catheter in the left ventricle of the heart and underwent a 25% total blood volume hemorrhage over 30 min, followed by either Zone 1 complete aortic occlusion (i.e., REBOA), Zone 1 endovascular variable aortic control (EVAC), or no occlusion as a control, for 45 min. Preload-independent metrics of cardiac performance were obtained at predetermined time points by performing inferior vena cava occlusion during a ventilatory pause. Continuous P-V loop data and other hemodynamic flow and pressure measurements were collected in real-time using a multi-channel data acquisition system.

Results

We developed a custom algorithm to quantify the time-dependent variance in both load-dependent and independent cardiac parameters from each P-V loop. As expected, all pigs displayed a significant decrease in the end-systolic pressures and volumes (i.e., ESP, ESV) after hemorrhage. The variability in response to hemorrhage was consistent across all three groups. However, upon introduction of REBOA, we observed significantly high levels of variability in both load-dependent and independent cardiac metrics such as ESP, ESV, and the slope of ESPVR (Ees). For instance, pigs receiving REBOA experienced a 342% increase in ESP from hemorrhage, while pigs receiving EVAC experienced only a 188% increase. The level of variability within the EVAC group was consistently less than that of the REBOA group, which suggests that the EVAC group may be more supportive of maintaining healthier cardiac performance than complete occlusion with REBOA.

Discussion

In conclusion, we successfully developed a novel algorithm to reliably quantify the single-beat and longitudinal P-V relations during hemorrhage and aortic occlusion. As expected, hemorrhage resulted in smaller P-V loops, reflective of decreased preload and afterload conditions; however, the cardiac output and heart rate were preserved. The use of REBOA and EVAC for 44 min resulted in the restoration of baseline afterload and preload conditions, but often REBOA exceeded baseline pressure conditions to an alarming level. The level of variability in response to REBOA was significant and could be potentially associated to cardiac injury. By quantifying each P-V loop, we were able to capture the variability in all P-V loops, including those that were irregular in shape and believe that this can help us identify critical time points associated with declining cardiac performance during hemorrhage and REBOA use.

Burn Care in Low-Resource and Austere Settings

More than 95% of the 11 million burns that occur annually happen in low-resource settings, and 70% of those occur among children. Although some low- and middle-income countries have well-organized emergency care systems, many have not prioritized care for the injured and experience unsatisfactory outcomes after burn injury. This chapter outlines key considerations for burn care in low-resource settings.

Impairment of Mesenteric Perfusion as a Marker of Major Bleeding in Trauma Patients

The majority of potentially preventable mortality in trauma patients is related to bleeding; therefore, early recognition and effective treatment of hemorrhagic shock impose a cardinal challenge for trauma teams worldwide. The reduction in mesenteric perfusion (MP) is among the first compensatory responses to blood loss; however, there is no adequate tool for splanchnic hemodynamic monitoring in emergency patient care. In this narrative review, (i) methods based on flowmetry, CT imaging, video microscopy (VM), measurement of laboratory markers, spectroscopy, and tissue capnometry were critically analyzed with respect to their accessibility, and applicability, sensitivity, and specificity. (ii) Then, we demonstrated that derangement of MP is a promising diagnostic indicator of blood loss. (iii) Finally, we discussed a new diagnostic method for the evaluation of hemorrhage based on exhaled methane (CH₄) measurement. Conclusions: Monitoring the MP is a feasible option for the evaluation of blood loss. There are a wide range of experimentally used methodologies; however, due to their practical limitations, only a fraction of them could be integrated into routine emergency trauma care. According to our comprehensive review, breath analysis, including exhaled CH₄ measurement, would provide the possibility for continuous, non-invasive monitoring of blood loss.

Silk composite interfacial layer eliminates rebleeding with chitosan-based hemostats

Chitosan foams are among the approved hemostats for pre-hospital hemorrhagic control but suffer from drawbacks related to mucoadhesiveness and rebleeding. Herein, we have developed a designer bilayered hemostatic foam consisting of a bioactive layer composed of silica particles (≈300 nm) and silk fibroin to serve as the tissue interfacing component on a chitosan foam. The foam composition was optimized based on the in vitro clotting behavior and cytocompatibility of individual components. In vivo analysis in a rat model demonstrated that the developed hemostat could achieve rapid clotting (31 ± 4 s), similar to a chitosan-based hemostat, but the former had significantly lower blood loss. Notably, removal of the bilayered hemostat prevented rebleeding, unlike the chitosan foam, which was associated with markedly higher incidences of rebleeding (50 %) and left behind material residue. Thus, the designer bilayered foam presented here is a potent inducer of blood clotting whilst affording easy removal with minimal rebleeding.

Facing Trauma and Surgical Emergency in Space: Hemorrhagic Shock

Although the risk of trauma in space is low, unpredictable events can occur that may require surgical treatment. Hemorrhage can be a life-threatening condition while traveling to another planet and after landing on it. These exploration missions call for a different approach than rapid return to Earth, which is the policy currently adopted on the International Space Station (ISS) in low Earth orbit (LEO). Consequences are difficult to predict, given the still scarce knowledge of human physiology in such environments. Blood loss in space can deplete the affected astronaut’s physiological reserves and all stored crew supplies. In this review, we will describe different aspects of hemorrhage in space, and by comparison with terrestrial conditions, the possible solutions to be adopted, and the current state of the art.

Perspectives on Competencies for Care in Austere Settings

LEVEL OF EVIDENCE

V, Expert Opinion.

Evaluation of the altitude impact on a point-of-care thromboelastography analyzer measurement: prerequisites for use in airborne medical evacuation courses

PURPOSE

Hemorrhagic shock is the first cause of preventable death in combat. Evacuations of wounded by aircraft are increasingly used and severely injured patients can spend consequent time in the air, mostly during strategic evacuation. In these situations, monitoring of blood coagulation may be pivotal in the management of blood product transfusion. Viscoelastic-guided transfusion is relevant in these situations. However, evaluation of these devices used in aircraft is lacking, especially the impact of decreased atmospheric pressure. The aim of this study is to evaluate the performance of an easy-to-carry viscoelastic system (TEG^® 6s, Haemonetics).

METHODS

First, TEG^® 6s repeatability, reproducibility, and correlation with chronometric methods and TEG-5000 were assessed on quality controls, healthy volunteers, and patients. Secondly, we tested the influence of vibrations and altitude on TEG^® 6s parameters (0ft vs. 8000 ft = 2428 m) and on quality control samples (normal and hypocoagulable).

RESULTS

TEG^® 6s exhibited good correlation with the reference method and TEG^® 5000. Repeatability and reproducibility CVs were satisfactory. The tests performed in the hypobaric chamber revealed that performance at 0 ft and 8000 ft (2428 m) for 9 out of 13 parameters was not significantly different. However, we showed a significant increasing of CRT.Alpha (p = 0.049), CK.Alpha, CK.MA (p < 0.001 and p < 0.01, respectively) and CFF.MA increased (p < 0.05).

CONCLUSION

Our study provides proof of concept to validate testing in an actual aeromedical situation. Indeed, TEG^® 6s appears to ease of use, resistance to high altitude conditions, and reliability on healthy humans. It is necessary to carry out a study on hemorrhagic injured patients in an aircraft.

Ranger O Low Titer (ROLO): Whole Blood Transfusion for Forward Deployed Units

First-time use of Ranger O Low Titer (ROLO) blood and implementation of a forward-walking blood bank using predetermined donors proved essential in the survival of a 33-year-old active duty soldier following a complex blast injury during combat operations. The patient sustained significant bone, soft tissue, and vascular damage and continued to deteriorate despite resuscitation with cold-stored whole blood (WB). Only after utilizing the ROLO battle drill and transfusing with fresh WB was the patient able to be stabilized and evacuated. In this case report, we discuss how ROLO walking blood bank takes the next step in aiding resuscitation, providing smaller, forward-deployed units with blood resupply without the administrative burden of storage, particularly in resource-scarce environments. We provide an overview of WB and contrast its use to that of component therapy. In conjunction with the Golden Hour, ROLO can be incorporated as the standard damage control resuscitation to reduce the risks of noncompressible hemorrhage. By taking precautionary steps in the pre-deployment setting, ROLO offers an invaluable alternative to conventional resuscitation.

Ex vivo hemostatic and immuno-inflammatory profiles of freeze-dried plasma

BACKGROUND

Hemorrhage is a leading cause of preventable death in civilian and military trauma. Freeze-dried plasma is promising for hemostatic resuscitation in remote prehospital settings, given its potential benefits in reducing blood loss and mortality, long storage at ambient temperatures, high portability, and rapid reconstitution for transfusion in austere environments. Here we assess the ex vivo characteristics of a novel Terumo's freeze-dried plasma product (TFDP).

STUDY DESIGN AND METHODS

Rotational thromboelastometry (ROTEM) tests (INTEM, EXTEM, and FIBTEM) were conducted on plasma samples at 37°C with a ROTEM delta-machine using standard reagents and procedures. The following samples were analyzed: pooled plasma to produce TFDP, TFDP reconstituted, and stored immediately at -80°C, reconstituted TFDP stored at 4°C for 24 h and room temperature (RT) for 4 h before freezing at -80°C. Analysis of plasma concentrations of selected cytokines, chemokines, and vascular molecules was performed using a multiplex immunoassay system. One-way ANOVA with post hoc tests assessed differences in hemostatic and inflammatory properties.

RESULTS

No significant differences in ROTEM variables (coagulation time [CT], clot formation time, α-angle, maximum clot firmness, and lysis index 30) between the TFDP-producing plasma and reconstituted TFDP samples were observed. Compared to control plasma, reconstituted TFDP stored at 4°C for 24 h or RT for 4 h showed a longer INTEM CT. Levels of immuno-inflammatory mediators were similar between frozen plasma and TFDP.

CONCLUSIONS

TFDP is equivalent to frozen plasma with respect to global hemostatic and immuno-inflammatory mediator profiles. Further investigations of TFDP in trauma-induced coagulopathy models and bleeding patients are warranted.

Platelet-enhanced plasma: Characterization of a novel candidate resuscitation fluid's extracellular vesicle content, clotting parameters, and thrombin generation capacity

BACKGROUND

Platelet transfusion is challenging in emergency medicine because of short platelet shelf life and stringent storage conditions. Platelet-derived extracellular vesicles (PEV) exhibit platelet-like properties. A plasma generated from expired platelet units rich in procoagulant PEV may be able to combine the benefits of plasma and platelets for resuscitation while increasing shelf life and utilizing an otherwise wasted resource.

STUDY DESIGN AND METHODS

Freeze-thaw cycling of platelet-rich plasma (PRP) followed by centrifugation to remove platelet remnants was utilized to generate platelet-enhanced plasma (PEP). An in vitro model of dilutional coagulopathy was also designed and used to test PEP. Rotational thromboelastometry and calibrated automated thrombography were used to assess clotting and extracellular vesicles (EV) procoagulant activity. Capture arrays were used to specifically measure EV subpopulations of interest (ExoView™, NanoView Biosciences). Captured vesicles were quantified and labeled with Annexin-V-FITC, CD41-PE, and CD63-AF647. Platelet alpha granule content (platelet-derived growth factor AB, soluble P-selectin, vascular endothelial growth factor A, and neutrophil activating peptide 2-chemokine (C-X-C motif) ligand 7) was measured. Commercially available platelet lysates were also characterized.

RESULTS

PEP is highly procoagulant, rich in growth factors, exhibits enhanced thrombin generation, and restores hemostasis within an in vitro model of dilutional coagulopathy. The predominant vesicle population were PEV with 7.0 × 10⁹ CD41+PS+ EV/ml compared to 4.7 × 10⁷ CD41+PS+ EV/ml in platelet-free plasma (p = .0079). Commercial lysates show impaired but rescuable clotting.

DISCUSSION

PEP is a unique candidate resuscitation fluid containing high PEV concentration with preliminary evidence, indicating a potential for upscaling the approach using platelet concentrates. Commercial lysate manufacturer workflows may be suitable for this, but further optimization and characterization of PEP is required.

Intrathoracic Pressure Regulator Performance in the Setting of Hemorrhage and Acute Lung Injury

INTRODUCTION

Intrathoracic pressure regulation (ITPR) can be utilized to enhance venous return and cardiac preload by inducing negative end expiratory pressure in mechanically ventilated patients. Previous preclinical studies have shown increased mean arterial pressure (MAP) and decreased intracranial pressure (ICP) with use of an ITPR device. The aim of this study was to evaluate the hemodynamic and respiratory effects of ITPR in a porcine polytrauma model of hemorrhagic shock and acute lung injury (ALI).

METHODS

Swine were anesthetized and underwent a combination of sham, hemorrhage, and/or lung injury. The experimental groups included: no injury with and without ITPR (ITPR, Sham), hemorrhage with and without ITPR (ITPR/Hem, Hem), and hemorrhage and ALI with and without ITPR (ITPR/Hem/ALI, Hem/ALI). The ITPR device was initiated at a setting of -3 cmH2O and incrementally decreased by 3 cmH2O after 30 minutes on each setting, with 15 minutes allowed for recovery between settings, to a nadir of -12 cmH2O. Histopathological analysis of the lungs was scored by blinded, independent reviewers. Of note, all animals were chemically paralyzed for the experiments to suppress gasping at ITPR pressures below -6 cmH2O.

RESULTS

Adequate shock was induced in the hemorrhage model, with the MAP being decreased in the Hem and ITPR/Hem group compared with Sham and ITPR/Sham, respectively, at all time points (Hem 54.2 ± 6.5 mmHg vs. 88.0 ± 13.9 mmHg, p < 0.01, -12 cmH2O; ITPR/Hem 59.5 ± 14.4 mmHg vs. 86.7 ± 12.1 mmHg, p < 0.01, -12 cmH2O). In addition, the PaO2/FIO2 ratio was appropriately decreased in Hem/ALI compared with Sham and Hem groups (231.6 ± 152.5 vs. 502.0 ± 24.6 (Sham) p < 0.05 vs. 463.6 ± 10.2, (Hem) p < 0.01, -12 cmH2O). Heart rate was consistently higher in the ITPR/Hem/ALI group compared with the Hem/ALI group (255 ± 26 bpm vs. 150.6 ± 62.3 bpm, -12 cmH2O) and higher in the ITPR/Hem group compared with Hem. Respiratory rate (adjusted to maintain pH) was also higher in the ITPR/Hem/ALI group compared with Hem/ALI at -9 and - 12 cmH2O (32.8 ± 3.0 breaths per minute (bpm) vs. 26.8 ± 3.6 bpm, -12 cmH2O) and higher in the ITPR/Hem group compared with Hem at -6, -9, and - 12 cmH2O. Lung compliance and end expiratory lung volume (EELV) were both consistently decreased in all three ITPR groups compared with their controls. Histopathologic severity of lung injury was worse in the ITPR and ALI groups compared with their respective injured controls or Sham.

CONCLUSION

In this swine polytrauma model, we demonstrated successful establishment of hemorrhage and combined hemorrhage/ALI models. While ITPR did not demonstrate a benefit for MAP or ICP, our data demonstrate that the ITPR device induced tachycardia with associated increase in cardiac output, as well as tachypnea with decreased lung compliance, EELV, PaO2/FIO2 ratio, and worse histopathologic lung injury. Therefore, implementation of the ITPR device in the setting of polytrauma may compromise pulmonary function without significant hemodynamic improvement.

Whole Blood, Fixed Ratio, or Goal-Directed Blood Component Therapy for the Initial Resuscitation of Severely Hemorrhaging Trauma Patients: A Narrative Review

This narrative review explores the pathophysiology, geographic variation, and historical developments underlying the selection of fixed ratio versus whole blood resuscitation for hemorrhaging trauma patients. We also detail a physiologically driven and goal-directed alternative to fixed ratio and whole blood, whereby viscoelastic testing guides the administration of blood components and factor concentrates to the severely bleeding trauma patient. The major studies of each resuscitation method are highlighted, and upcoming comparative trials are detailed.

Stepping stones to the future of haemoglobin-based blood products: clinical, preclinical and innovative examples

Critical overview of the different oxygen therapeutics developed so far to be used when donor blood is not available.

Multiple trauma management in mountain environments - a scoping review : Evidence based guidelines of the International Commission for Mountain Emergency Medicine (ICAR MedCom). Intended for physicians and other advanced life support personnel

Background

Multiple trauma in mountain environments may be associated with increased morbidity and mortality compared to urban environments.

Objective

To provide evidence based guidance to assist rescuers in multiple trauma management in mountain environments.

Eligibility criteria

All articles published on or before September 30th 2019, in all languages, were included. Articles were searched with predefined search terms.

Sources of evidence

PubMed, Cochrane Database of Systematic Reviews and hand searching of relevant studies from the reference list of included articles.

Charting methods

Evidence was searched according to clinically relevant topics and PICO questions.

Results

Two-hundred forty-seven articles met the inclusion criteria. Recommendations were developed and graded according to the evidence-grading system of the American College of Chest Physicians. The manuscript was initially written and discussed by the coauthors. Then it was presented to ICAR MedCom in draft and again in final form for discussion and internal peer review. Finally, in a face-to-face discussion within ICAR MedCom consensus was reached on October 11th 2019, at the ICAR fall meeting in Zakopane, Poland.

Conclusions

Multiple trauma management in mountain environments can be demanding. Safety of the rescuers and the victim has priority. A crABCDE approach, with haemorrhage control first, is central, followed by basic first aid, splinting, immobilisation, analgesia, and insulation. Time for on-site medical treatment must be balanced against the need for rapid transfer to a trauma centre and should be as short as possible. Reduced on-scene times may be achieved with helicopter rescue. Advanced diagnostics (e.g. ultrasound) may be used and treatment continued during transport.

Mitigating Ischemia-Reperfusion Injury Using a Bilobed Partial REBOA Catheter: Controlled Lower-Body Hypotension

BACKGROUND

Non-compressible torso hemorrhage (NCTH) is the leading cause of potentially preventable death on the battlefield. Resuscitative endovascular balloon occlusion of the aorta (REBOA) aims to restore central blood pressure and control NCTH below the balloon, but risks ischemia-reperfusion injury to distal organs when prolonged. We tested a bilobed partial REBOA catheter (pREBOA), which permits some of the blood to flow past the balloon.

METHODS

Female swine (n = 37, 6 groups, n = 5-8/group), anesthetized and instrumented, were exponentially hemorrhaged 50% of estimated blood volume (all except time controls [TC]). Negative controls (NC) did not receive REBOA or resuscitation. Positive controls (PC) received retransfusion after 120 min. REBOA groups received REBOA for 120 min, then retransfusion. Balloon was fully inflated in the full REBOA group (FR), and was partially inflated in partial REBOA groups (P45 and P60) to achieve a distal systolic blood pressure of 45 mm Hg or 60 mm Hg.

RESULTS

Aortic occlusion restored baseline values of proximal mean arterial pressure, cardiac output, and carotid flow in pREBOA groups. Lactate reached high values during occlusion in all REBOA groups (9.9 ± 4.2, 8.0 ± 4.1, and 10.7 ± 2.9 for P45, P60, and FR), but normalized by 6 to 12 h post-deflation in the partial groups. All TC and P60 animals survived 24 h. The NC, PC, and P45 groups survived 18.2 ± 9.5, 19.3 ± 10.6, and 21.0 ± 8.4 h. For FR animals mean survival was 6.2 ± 5.8 h, significantly worse than all other animals (P < 0.01, logrank test).

CONCLUSIONS

In this porcine model of hemorrhagic shock, animals undergoing partial REBOA for 120 min survived longer than those undergoing full occlusion.

Hemoglobin-based Oxygen Carriers: Current State-of-the-art and Novel Molecules

In blood, the primary role of red blood cells (RBCs) is to transport oxygen via highly regulated mechanisms involving hemoglobin (Hb). Hb is a tetrameric porphyrin protein comprising of two α- and two β-polypeptide chains, each containing an iron-containing heme group capable of binding one oxygen molecule. In military as well as civilian traumatic exsanguinating hemorrhage, rapid loss of RBCs can lead to suboptimal tissue oxygenation and subsequent morbidity and mortality. In such cases, transfusion of whole blood or RBCs can significantly improve survival. However, blood products including RBCs present issues of limited availability and portability, need for type matching, pathogenic contamination risks, and short shelf-life, causing substantial logistical barriers to their prehospital use in austere battlefield and remote civilian conditions. While robust research is being directed to resolve these issues, parallel research efforts have emerged toward bioengineering of semisynthetic and synthetic surrogates of RBCs, using various cross-linked, polymeric, and encapsulated forms of Hb. These Hb-based oxygen carriers (HBOCs) can potentially provide therapeutic oxygenation when blood or RBCs are not available. Several of these HBOCs have undergone rigorous preclinical and clinical evaluation, but have not yet received clinical approval in the USA for human use. While these designs are being optimized for clinical translations, several new HBOC designs and molecules have been reported in recent years, with unique properties. The current article will provide a comprehensive review of such HBOC designs, including current state-of-the-art and novel molecules in development, along with a critical discussion of successes and challenges in this field.

Can Resuscitative Endovascular Balloon Occlusion of the Aorta Fly? Assessing Aortic Balloon Performance for Aeromedical Evacuation

BACKGROUND

Noncompressible torso hemorrhage remains a leading cause of death. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) placement may occur before transport; however, its efficacy has not been demonstrated at altitude. We hypothesized that changes in altitude would not result in blood pressure changes proximal to a deployed REBOA.

METHODS

A simulation model for 7Fr guidewireless REBOA was used at altitudes up to 22,000 feet. Female pigs then underwent hemorrhagic shock to a mean arterial pressure (MAP) of 40 mm Hg. After hemorrhage, a REBOA catheter was deployed in the REBOA group and positioned but not inflated in the no-REBOA group. Animals underwent simulated aeromedical evacuation at 8000 ft or were left at ground level. After altitude exposure, the balloon was deflated, and the animals were observed.

RESULTS

Taking the REBOA catheter to 22,000 ft in the simulation model resulted in a lower systolic blood pressure but a preserved MAP. In the porcine model, REBOA increased both systolic blood pressure and MAP compared with no-REBOA (P < 0.05) and was unaffected by altitude. No differences in postflight blood pressure, acidosis, or systemic inflammatory response were observed between ground and altitude REBOA groups.

CONCLUSIONS

REBOA maintained MAP up to 22,000 feet in an inanimate model. In the porcine model, REBOA deployment improved MAP, and the balloon remained effective at altitude.

Hemostatic agents for prehospital hemorrhage control: a narrative review

Hemorrhage is the leading cause of preventable death in combat trauma and the secondary cause of death in civilian trauma. A significant number of deaths due to hemorrhage occur before and in the first hour after hospital arrival. A literature search was performed through PubMed, Scopus, and Institute of Scientific Information databases for English language articles using terms relating to hemostatic agents, prehospital, battlefield or combat dressings, and prehospital hemostatic resuscitation, followed by cross-reference searching. Abstracts were screened to determine relevance and whether appropriate further review of the original articles was warranted. Based on these findings, this paper provides a review of a variety of hemostatic agents ranging from clinically approved products for human use to newly developed concepts with great potential for use in prehospital settings. These hemostatic agents can be administered either systemically or locally to stop bleeding through different mechanisms of action. Comparisons of current hemostatic products and further directions for prehospital hemorrhage control are also discussed.

Differing Resuscitation With Aortic Occlusion in a Swine Junctional Hemorrhage Polytrauma Model

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) and Abdominal Aortic and Junctional Tourniquet (AAJT) have received much attention in recent as methods for temporary control of junctional hemorrhage. Previous studies typically used the animal's shed blood for resuscitation. With current interest in moving REBOA to prehospital environment, this study aimed to evaluate the hemodynamic and metabolic responses to different resuscitation fluids used with these devices.

METHODS

In swine (Sus scrofa), shock was induced using a controlled hemorrhage, femur fracture, and uncontrolled hemorrhage from the femoral artery. Infrarenal REBOA or AAJT was deployed for 60 min during which the arterial injury was repaired. Animals were resuscitated with 15 mL/kg of shed whole blood (SWB) or fresh frozen plasma (FFP) or 30 mL/kg of a balanced crystalloid (PlasmaLyte).

RESULTS

Animals in the AAJT and REBOA groups did not show any measurable differences in hemodynamics, metabolic responses, or survival with AAJT or REBOA treatment; hence, the data are pooled and analyzed among the three resuscitative fluids. SWB, FFP, and PlasmaLyte groups did not have a difference in survival time or overall survival. The animals in the SWB and FFP groups maintained higher blood pressure after resuscitation, (P < 0.001) and required significantly less norepinephrine to maintain blood pressure than those in the PlasmaLyte group (P < 0.001). The PlasmaLyte resuscitation prolonged prothrombin time and decreased thromboelastography maximum amplitude.

CONCLUSIONS

After 60 min, infrarenal REBOA or AAJT aortic occlusion SWB and FFP resuscitation provided better blood pressure support with half of the resuscitative volume of PlasmaLyte. Swine resuscitated with SWB and FFP also had a more favorable coagulation profile. These data suggest that whole blood or component therapy should be used for resuscitation in conjunction with REBOA or AAJT, and administration of these fluids should be considered if prehospital device use is pursued.

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.

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.

Health Support for a Remote Industrial Site

This publication is derived from and rooted in the authors' experience in designing the Health Support of a remote industrial site. Summarizing the main steps of this design is the purpose of the approach. As a first step devoted to “Evaluation” (Chapters 1–5) are displayed the fundamentals for designing a Project Health Plan, such as a realistic and operative definition of “patient stabilization” and the principles of tactical reasoning for Medevacs, specifying how pathophysiology and logistic constraints should be correlated. A core element of the conceptual work consists in partnering these two domains, which usually each go their own way. Both should be considered in terms of delays: in life threatening situations, pathophysiology allows for a (maximum) delay before effective stabilization, while logistics dictates a (minimum) delay for reaching a stabilization facility. Ensuring that these two delays match is the desired result. Clearly, this conceptual work will unfold its full potential in low sanitary level countries, where most industrial commodities Projects take place, and where these delays are the longest. Next is detailed the audit/study preparation, i.e., the data gathering needed to get a clear picture of the Project conditions and concerns, workforce headcount and pattern, evacuation vectors and delays, and reference documents. Finally, risk assessment and a review of health facilities—in the vicinity and further away—complete the evaluation work. In a second phase devoted to “Implementation” (Chapters 6–9) is detailed how contracts with health providers, and health exhibits of industrial contracts should be conceived, and how on-site health support is designed, from the necessity of a pre-employment check to the design and organization of routine and emergency medicine facilities. Emergency preparedness and response plans, as well as medical coordination, should integrate with the HSE command chart. Overall, this document strongly advocates for joint engineering between HSE officers and medical specialists. An overview of key points for hygiene—often a separate topic covered in an offprint—is proposed. Finally, forward guidance for writing the audit/study report is proposed. This audit/study report must result in conclusive recommendations. Hence, a guide is proposed so that the report becomes a matrix of the Health Plan itself, and will be ended by a summary of findings and recommendations ready-to-use in Project management. In this way, the Health Plan will be launched, and gradually evolve and be amended as a “living document” throughout the lifetime of the Project.

Intérêt de l’échographie dans la prise en charge du blessé de guerre dyspnéique

La médecine militaire s’adapte aux dernières évolutions médicales, et l’échographie s’inscrit désormais dans les algorithmes de prise en charge des blessés de guerre. Grâce à la plus-value apportée à la clinique dans l’évaluation des blessés associée à l’amélioration des performances et à la miniaturisation des appareils, le positionnement de l’échographie en médecine de guerre a évolué pour trouver sa place « à l’avant », parfois dans des conditions sanitaires très dégradées. Après avoir rappelé les principes du secourisme au combat pour le blessé de guerre dyspnéique, cet article replace l’intérêt diagnostique et thérapeutique de l’échographie dans la « médecine de l’avant » en détaillant la sémiologie échographique des principales pathologies du blessé de guerre dans la phase de réanimation préhospitalière. L’article souligne aussi l’importance opérationnelle qu’occupe l’échographie, que ce soit sur le terrain lors des évacuations sanitaires ou lors d’afflux massif de victimes. Certains aspects de la doctrine militaire d’emploi pourraient s’adapter à la pratique en préhospitalier ou lors des situations d’exception en métropole.

Blood transfusion management in the severely bleeding military patient

PURPOSE OF REVIEW

Hemorrhage remains the primary cause of preventable death on the battlefield and in civilian trauma. Hemorrhage control is multifactorial and starts with point-of-injury care. Surgical hemorrhage control and time from injury to surgery is paramount; however, interventions in the prehospital environment and perioperative period affect outcomes. The purpose of this review is to understand concepts and strategies for successful management of the bleeding military patient. Understanding the life-threatening nature of coagulopathy of trauma and implementing strategies aimed at full spectrum hemorrhage management from point of injury to postoperative care will result in improved outcomes in patients with life-threatening bleeding.

RECENT FINDINGS

Timely and appropriate therapies impact survival. Blood product resuscitation for life-threatening hemorrhage should either be with whole blood or a component therapy strategy that recapitulates the functionality of whole blood. The US military has transfused over 10 000 units of whole blood since the beginning of the wars in Iraq and Afghanistan. The well recognized therapeutic benefits of whole blood have pushed this therapy far forward into prehospital care in both US and international military forces. Multiple hemostatic adjuncts are available that are likely beneficial to the bleeding military patient; and other products and techniques are under active investigation.

SUMMARY

Lessons learned in the treatment of combat casualties will likely continue to have positive impact and influence and the management of hemorrhage in the civilian trauma setting.

Prehospital Plasma during Air Medical Transport in Trauma Patients at Risk for Hemorrhagic Shock

BACKGROUND

After a person has been injured, prehospital administration of plasma in addition to the initiation of standard resuscitation procedures in the prehospital environment may reduce the risk of downstream complications from hemorrhage and shock. Data from large clinical trials are lacking to show either the efficacy or the risks associated with plasma transfusion in the prehospital setting.

METHODS

To determine the efficacy and safety of prehospital administration of thawed plasma in injured patients who are at risk for hemorrhagic shock, we conducted a pragmatic, multicenter, cluster-randomized, phase 3 superiority trial that compared the administration of thawed plasma with standard-care resuscitation during air medical transport. The primary outcome was mortality at 30 days.

RESULTS

A total of 501 patients were evaluated: 230 patients received plasma (plasma group) and 271 received standard-care resuscitation (standard-care group). Mortality at 30 days was significantly lower in the plasma group than in the standard-care group (23.2% vs. 33.0%; difference, -9.8 percentage points; 95% confidence interval, -18.6 to -1.0%; P=0.03). A similar treatment effect was observed across nine prespecified subgroups (heterogeneity chi-square test, 12.21; P=0.79). Kaplan-Meier curves showed an early separation of the two treatment groups that began 3 hours after randomization and persisted until 30 days after randomization (log-rank chi-square test, 5.70; P=0.02). The median prothrombin-time ratio was lower in the plasma group than in the standard-care group (1.2 [interquartile range, 1.1 to 1.4] vs. 1.3 [interquartile range, 1.1 to 1.6], P<0.001) after the patients' arrival at the trauma center. No significant differences between the two groups were noted with respect to multiorgan failure, acute lung injury-acute respiratory distress syndrome, nosocomial infections, or allergic or transfusion-related reactions.

CONCLUSIONS

In injured patients at risk for hemorrhagic shock, the prehospital administration of thawed plasma was safe and resulted in lower 30-day mortality and a lower median prothrombin-time ratio than standard-care resuscitation. (Funded by the U.S. Army Medical Research and Materiel Command; PAMPer ClinicalTrials.gov number, NCT01818427 .).

Novel concepts for damage control resuscitation in trauma

PURPOSE OF REVIEW

Traumatic injuries are a major cause of mortality worldwide. Damage control resuscitation or balanced transfusion of plasma, platelets, and red blood cells for the management of exsanguinating hemorrhage after trauma has become the standard of care. We review the literature regarding the use of alternatives to achieve the desired 1 : 1:1 ratio as availability of plasma and platelets can be problematic in some environments.

RECENT FINDINGS

Liquid and freeze dried plasma (FDP) are logistically easier to use and may be superior to fresh frozen plasma. Cold storage platelets (CSPs) have improved hemostatic properties and resistance to bacterial contamination. Low titer type O whole blood can be transfused safely in civilian patients.

SUMMARY

In the face of hemorrhagic shock from traumatic injury, resuscitation should be initiated with 1 : 1 : 1 transfusion of plasma, platelets, and red blood cells with limited to no use of crystalloids. Availability of plasma and platelets is limited in some environments. In these situations, the use of low titer type O whole blood, thawed or liquid plasma, cold stored platelets or reconstituted FDP can be used as substitutes to achieve optimal transfusion ratios. The hemostatic properties of CSPs may be superior to room temperature platelets.

The Chemistry of Lyophilized Blood Products

With the development of new biologics and bioconjugates, storage and preservation have become more critical than ever before. Lyophilization is a method of cell and protein preservation by removing a solvent such as water from a substance followed by freezing. This technique has been used in the past and still holds promise for overcoming logistic challenges in safety net hospitals with limited blood banking resources, austere environments such as combat, and mass casualty situations where existing resources may be outstripped. This method allows for long-term storage and transport but requires the bioconjugation of preservatives to prevent cell destabilization. Trehalose is utilized as a bioconjugate in platelet and red blood cell preservation to maintain protein thermodynamics and stabilizing protein formulations in liquid and freeze-dried states. Biomimetic approaches have been explored as alternatives to cryo- and lyopreservation of blood components. Intravascular hemostats such as PLGA nanoparticles functionalized with PEG motifs, topical hemostats utilizing fibrinogen or chitosan, and liposomal encapsulated hemoglobin with surface modifications are effectively stored long-term through bioconjugation. In thinking about the best methods for storage and transport, we are focusing this topical review on blood products that have the longest track record of preservation and looking at how these methods can be applied to synthetic systems.