Hemorrhagic blood failure: Oxygen debt, coagulopathy, and endothelial damage

Mechanism of secondary renal injury in traumatic hemorrhagic shock model under a dry and heat desert environment

We established a swine model of traumatic hemorrhagic shock to assess secondary renal injury under dry-heat conditions to clarify the roles of cell pyroptosis and inflammatory response in traumatic hemorrhagic shock development. Sixty-eight domestic Landrace piglets were divided into normothermic environment, dry-heat sham surgery, and dry-heat environment traumatic hemorrhagic shock groups (four subgroups: 3 h of environmental exposure and 60, 120, and 180 min after inducing traumatic hemorrhagic shock). The kidneys and blood were sampled at various time points. Univariate analysis of variance or non-parametric test was used for intergroup and intragroup comparisons, and the least significant difference test was used for multiple comparisons. The serum lipopolysaccharide, neutrophil gelatinase-associated lipocalin, kidney injury molecule 1, blood urea nitrogen, and creatinine levels, as well as various inflammatory factors, oxidative stress indicators, and Paller score, were significantly higher under dry-heat environment traumatic hemorrhagic shock than under normothermic environment and dry-heat sham surgery at 180 min. The histopathological damage in the dry-heat environment traumatic hemorrhagic shock group increased significantly at 180 min. Immunohistochemistry, western blotting, and terminal deoxynucleotidyl transferase dUTP nick end labeling assays showed that protein expression and apoptosis index values in the renal tissues of all three groups increased but were significantly higher under dry-heat environment traumatic hemorrhagic shock than under normothermic environment and dry-heat sham surgery at 180 min. The combination of dry-heat environment and traumatic hemorrhagic shock induces an aggravation of secondary renal injury, which may be related to cell pyroptosis, inflammatory response, apoptosis, and oxidative stress. Our findings may assist in the development of treatments for acute kidney injury.

Hemorrhagic Shock and Mitochondria: Pathophysiology and Therapeutic Approaches

Severe injuries and some pathologies associated with massive bleeding, such as maternal hemorrhage, gastrointestinal and perioperative bleeding, and rupture of an aneurysm, often lead to major blood loss and the development of hemorrhagic shock. A sharp decrease in circulating blood volume triggers a vicious cycle of vasoconstriction and coagulopathy leading to ischemia of all internal organs and, in severe decompensated states, ischemia of the brain and heart. The basis of tissue damage and dysfunction in hemorrhagic shock is an interruption in the supply of oxygen and substrates for energy production to the cells, making the mitochondria a source and target of oxidative stress and proapoptotic signaling. Based on these mechanisms, different strategies are proposed to treat the multiple organ failure that occurs in shock. The main direction of such treatment is to provide the cells with a sufficient amount of substrates that utilize oxidative phosphorylation at different stages and increase the efficiency of energy production by the mitochondria. These strategies include restoring the efficiency of mitochondrial complexes, for example, by restoring the nicotinamide adenine dinucleotide (NAD) pool. Another direction is approaches to minimize oxidative stress as well as apoptosis, which are primarily dependent on the mitochondria. There are also a number of other methods to reduce mitochondrial dysfunction and improve the quality of the mitochondrial population. In this review, we consider such strategies for the treatment of hemorrhagic shock and show the promise of therapeutic approaches aimed at restoring the bioenergetic functions of the cell and protecting mitochondria.

Resonant acoustic rheometry for assessing plasma coagulation in bleeding patients

Disordered hemostasis associated with life-threatening hemorrhage commonly afflicts patients in the emergency department, critical care unit, and perioperative settings. Rapid and sensitive hemostasis phenotyping is needed to guide administration of blood components and hemostatic adjuncts to reverse aberrant hemostasis. Here, we report the use of resonant acoustic rheometry (RAR), a technique that quantifies the viscoelastic properties of soft biomaterials, for assessing plasma coagulation in a cohort of 38 bleeding patients admitted to the hospital. RAR captured the dynamic characteristics of plasma coagulation that were dependent on coagulation activators or reagent conditions. RAR coagulation parameters correlated with TEG reaction time and TEG functional fibrinogen, especially when stratified by comorbidities. A quadratic classifier trained on selective RAR parameters predicted transfusion of fresh frozen plasma and cryoprecipitate with modest to high overall accuracy. While these results demonstrate the feasibility of RAR for plasma coagulation and utility of a machine learning model, the relative small number of patients, especially the small number of patients who received transfusion, is a limitation of this study. Further studies are need to test a larger number of patients to further validate the capability of RAR as a cost-effective and sensitive hemostasis assay to obtain quantitative data to guide clinical-decision making in managing severely hemorrhaging patients.

IL-1β primed mesenchymal stromal cells moderate hemorrhagic shock-induced vascular permeability

BACKGROUND

Hemorrhagic shock (HS) corresponds to absolute hypovolemia creating an imbalance between oxygen supply and consumption. This causes an impaired hemostasis, a systemic inflammatory response, and microvascular permeability which can lead to multiple organ failure (MOF). There is no specific treatment for the endothelial dysfunction that plays a major role in the evolution towards MOF. Mesenchymal stromal cells (MSC) have been used in clinical trials for their immunomodulation and tissue repair capabilities for many years. Moreover, we previously showed that IL-1β-primed-MSC (MSCp) attenuated HS-induced organ injuries. The objective of the study was to determine whether MSCp could prevent the onset of MOF after HS by preventing endothelial dysfunction.

METHODS

We established a rat model of HS, inducing 90 min of HS at a fixed mean arterial pressure of 35 mmHg, followed by resuscitation and transfusion. MSCp treatment was administered intravenously at the onset of resuscitation. After 6 h, we assessed plasma levels of endothelial markers, vascular permeability using Evans Blue (EB) dye, and renal and hepatic water content by measuring the wet-to-dry weight difference. Additionally, we investigated the ability of MSCp to inhibit leukocyte adhesion to activated endothelium in vitro.

RESULTS

Our results indicate that early administration of MSCp significantly reduced the percentage of water content and EB dye in the liver but not in the kidney. These results were associated with a trend toward decreased plasma levels of Syndecan-1, ICAM-1, vWF, and VCAM-1. In vitro, MSCp reduced leukocyte-endothelial cell adhesion. Together, our results suggest that MSCp help to prevent endothelial dysfunction and vascular leakage, which, in turn, could protect the liver from injury.

Phospholipid Nanoparticles: A Novel Colloid for Blood Volume Replacement, Reanimation, and Organ Protection in Hemorrhagic Shock

Background/Objectives: Exsanguination is a leading cause of preventable death in military and civilian settings due to extensive blood loss and hemorrhagic shock, which trigger systemic effects such as impaired tissue perfusion, hypoxia, inflammation, and multi-organ dysfunction. Standard resuscitation restores blood volume but fails to address critical aspects of hemorrhagic shock, including inflammation, coagulopathy, and reperfusion injury. To address these limitations, novel phospholipid nanoparticle (PNP)-based resuscitative fluids, VBI-S and VBI-1, were developed to modulate nitric oxide (NO) levels, improving hemodynamic stability, tissue oxygenation, and reducing inflammatory injury. This study assessed the potential of novel phospholipid nanoparticle fluids, VBI-S and VBI-1, as resuscitative agents for severe hemorrhagic shock by evaluating their ability to regulate nitric oxide, restore blood pressure, and mitigate ischemia-reperfusion injury. Methods: This study involved two phases with Sprague Dawley rats (n = 6 per group). Phase one, lasting 4 h, included four groups: blood, Ringer's lactate, VBI-S, and VBI-1. Phase two, lasting 12 h, comprised sham, blood, and VBI-1 groups. Under anesthesia, one femoral artery was catheterized for blood pressure monitoring, and blood withdrawal from the other induced apnea. Reanimation was performed using an intra-arterial infusion of shed blood, Ringer's lactate, VBI-S, or VBI-1. Tissue samples were analyzed histologically and for oxidative DNA damage via immunofluorescence. Chemiluminescence and rheology assessed nitric oxide interactions and viscosity. Data were analyzed using ANOVA. Results: VBI-1 and shed blood increased mean arterial pressure (MAP) from <10 mmHg to survivable levels sustained for 12 h, with VBI-1 showing significantly higher MAP at 3-4 h. Rats treated with Ringer's lactate died within 30 min. Histology revealed reduced organ damage in VBI-1-treated rats compared to shed blood. Immunohistochemistry indicated significantly less oxidative DNA damage (p < 0.001) in VBI-1-treated rats. VBI-1 exhibited superior viscosity and nitric oxide binding. Conclusions: VBI-1 demonstrates strong potential as a resuscitative fluid, offering blood pressure restoration, reduced oxidative damage, and enhanced tissue perfusion, with significant implications for use in resource-limited and pre-hospital settings.

Association of endotheliopathy with coagulofibrinolytic reactions and disseminated intravascular coagulation after trauma: a retrospective observational study

We carried out a retrospective observational investigation to explore the association of endotheliopathy with coagulofibrinolytic reactions and the progression of disseminated intravascular coagulation (DIC) in adult trauma patients. We measured syndecan-1 (SDC-1), an indicator of endotheliopathy, and biomarkers of coagulofibrinolysis in 100 trauma patients immediately transferred to Ehime University Hospital. We evaluated the correlations between the coagulofibrinolytic parameters and SDC-1. We also investigated the association between SDC-1 elevations and the development of DIC, and determined the discriminators of DIC development. The median SDC-1 concentration was 82.7 (43.5-178.1) ng/mL. DIC developed in 16 patients (16.0%), and SDC-1 concentrations were significantly higher in DIC patients than in non-DIC patients (218.8 [134.5-798.2] ng/mL vs. 67.2 [39.6-114.5] ng/mL, p < 0.001). Receiver operating characteristic curve analysis revealed that the circulating SDC-1 level effectively predicted the progression of DIC, with an area under the curve of 0.862 (95% confidence interval [CI], 0.789-0.936). The optimal cut-off value was determined to be 92.5 ng/mL, yielding a sensitivity of 100.0% and a specificity of 67.8% (p < 0.001). A simple logistic regression analysis showed that a circulating SDC-1 concentration of > 92.5 ng/mL was significantly correlated with DIC progression (odds ratio [OR], 31.67; 95%CI: 3.97-252.31, p = 0.001). Many coagulofibrinolytic parameters were significantly correlated with SDC-1. Estimating the discriminators of DIC development by the least absolute shrinkage and selection operator (LASSO) and elastic-net regression analysis identified markers of coagulofibrinolytic activation, such as thrombin-antithrombin complex (TAT) and tissue plasminogen activator (tPA). A multivariate logistic regression model using TAT, tPA, and SDC-1 demonstrated that TAT and tPA, but not SDC-1, were independent factors predicting the development of DIC (TAT per 10 µg/L: OR, 1.14, 95%CI: 1.05-1.24, p = 0.003; tPA per 100pg/mL: OR, 1.03, 95%CI: 1.01-1.05, p = 0.003; SDC-1 per 10ng/mL: OR, 1.00, 95%CI: 0.99-1.01, p = 0.973). Mediation analysis showed that SDC-1 elevation was predominantly associated with the development of DIC indirectly through the increase in TAT (proportion mediated = 96.1%, p < 0.001), while there was no significant indirect effect of SDC-1 elevation on the role of TAT elevation in DIC development was observed (p = 0.340). The primary pathogenesis of DIC in the acute phase of trauma is likely driven by coagulofibrinolytic activation. Endotheliopathy, as reflected by elevated circulating levels of SDC-1, is strongly associated with coagulofibrinolytic responses. Although endotheliopathy may contribute to the early development of DIC through coagulation activation, its role appears to be limited.

Towards chlorocytes for therapeutic intravascular photosynthesis

Aerobic metabolism relies on external oxygen production through photosynthesis and its subsequent transport into each cell of the body via the cardiorespiratory system. This mechanism has successfully evolved over millions of years, enabling animals to inhabit most environments on Earth. However, the insufficient oxygen supply leads to several clinical problems, ranging from non-healing wounds to tumor resistance to therapy. Given that photosynthetic microorganisms are capable of producing oxygen and removing carbon dioxide from the environment, over the last decade, several groups worldwide have proposed their potential use as an alternative tissue oxygenation approach. While most studies have demonstrated safety and efficacy after local tissue administration, recent studies have also suggested that systemic administration could trigger intravascular photosynthesis. If successful, the development of a new generation of circulating cells, known as chlorocytes, may partially replace the role of erythrocytes in gas exchange within the body, without relying on external supply and vascular flow. This work reviews the existing literature on local and systemic administration of photosynthetic microorganisms, highlighting the main challenges in the field and potential solutions to unleash the enormous potential clinical impact of chlorocytes and intravascular photosynthesis. KEY POINTS: • Circulating photosynthetic microorganisms could deliver oxygen to tissues • Microalgae and cyanobacteria have shown safety and efficacy for oxygen delivery • Several key challenges need to be addressed for the clinical success of chlorocytes.

Resonant Acoustic Rheometry for Real Time Assessment of Plasma Coagulation in Bleeding Patients

Disordered hemostasis associated with life-threatening hemorrhage commonly afflicts patients in the emergency room, critical care unit, and perioperative settings. Rapid and sensitive hemostasis phenotyping is needed to guide administration of blood components and hemostatic adjuncts to reverse aberrant coagulofibrinolysis. Here, resonant acoustic rheometry (RAR), a technique that quantifies the viscoelastic properties of soft biomaterials, was applied to assess plasma coagulation in a cohort of bleeding patients with concomitant clinical coagulation assays and whole blood thromboelastography (TEG) as part of their routine care. RAR captured the dynamic characteristics of plasma coagulation that were coagulation activators-dependent. RAR coagulation parameters correlated with TEG reaction time and TEG functional fibrinogen, especially when stratified by comorbidities. A quadratic classifier trained on RAR parameters predicted transfusion of fresh frozen plasma and cryoprecipitate with high overall accuracy. These results demonstrate the potential of RAR as a bedside hemostasis assessment to guide transfusion in bleeding patients.

Plasma as endothelial rescue in septic shock: A randomized, phase 2a pilot trial

BACKGROUND

Septic shock is associated with high morbidity and mortality, the endothelium plays an important role. Crystalloids is standard of care to maintain intravascular volume. Plasma is associated with improved endothelial integrity and restoration of the glycocalyx layer. We evaluated the efficacy and safety aspects of cell-free and pathogen inactivated pooled plasma (OctaplasLG®) as resuscitation in septic shock patients.

STUDY DESIGN AND METHODS

This randomized, investigator-initiated phase IIa trial ran at a Danish single center intensive care unit, from 2017 to 2019. Patients were 18 years of age or older with septic shock and randomized to fluid optimization with OctaplasLG® or Ringer-acetate in the first 24 h. The primary endpoints were changes in biomarkers indicative of endothelial activation, damage, and microvascular perfusion from baseline to 24 h. Safety events and mortality were assessed during 90 days.

RESULTS

Forty-four patients were randomized, 20 to OctaplasLG versus 24 to Ringer-acetate. The median age was 69, and 55% were men. Median Sequential Organ Failure Assessment score was 13. Baseline differences favoring the Ringer-acetate group were observed. The OctaplasLG® group was resuscitated with 740 mL plasma and the Ringer-acetate group with 841 mL crystalloids. There was no significant change in the microvascular perfusion or five biomarkers except VEGFR1 change, which was higher in patients receiving OctaplasLG® 0.12(SD 0.37) versus Ringer-acetate -0.24 (SD 0.39), with mean difference 0.36 (95% CI, 0.13-0.59, p = .003) in favor of Ringer-acetate.

DISCUSSION

This study found that fluid resuscitation with OctaplasLG® in critically ill septic shock patients is feasible. Baseline confounding prevented assessment of the potential effect of OctaplasLG®.

Markers of Futile Resuscitation in Traumatic Hemorrhage: A Review of the Evidence and a Proposal for Futility Time-Outs during Massive Transfusion

The reduction in the blood supply following the 2019 coronavirus pandemic has been exacerbated by the increased use of balanced resuscitation with blood components including whole blood in urban trauma centers. This reduction of the blood supply has diminished the ability of blood banks to maintain a constant supply to meet the demands associated with periodic surges of urban trauma resuscitation. This scarcity has highlighted the need for increased vigilance through blood product stewardship, particularly among severely bleeding trauma patients (SBTPs). This stewardship can be enhanced by the identification of reliable clinical and laboratory parameters which accurately indicate when massive transfusion is futile. Consequently, there has been a recent attempt to develop scoring systems in the prehospital and emergency department settings which include clinical, laboratory, and physiologic parameters and blood products per hour transfused as predictors of futile resuscitation. Defining futility in SBTPs, however, remains unclear, and there is only nascent literature which defines those criteria which reliably predict futility in SBTPs. The purpose of this review is to provide a focused examination of the literature in order to define reliable parameters of futility in SBTPs. The knowledge of these reliable parameters of futility may help define a foundation for drawing conclusions which will provide a clear roadmap for traumatologists when confronted with SBTPs who are candidates for the declaration of futility. Therefore, we systematically reviewed the literature regarding the definition of futile resuscitation for patients with trauma-induced hemorrhagic shock, and we propose a concise roadmap for clinicians to help them use well-defined clinical, laboratory, and viscoelastic parameters which can define futility.

Damage Control Resuscitation in Traumatic Hemorrhage: It Is More Than Fixing the Holes and Filling the Tank

Damage control resuscitation is the foundation of hemorrhagic shock management and includes early administration of plasma, tranexamic acid, and limited crystalloid-containing products.

Oxygen debt as a predictor of high-flow nasal cannula therapy failure in SARS-CoV-2 patients with acute respiratory failure: A retrospective cohort study

BACKGROUND

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is known for its rapid progression to acute hypoxemic respiratory failure (AHRF). The increased use of oxygen therapy during the pandemic and the progression of AHRF have highlighted the need to promptly determine the need for orotracheal intubation (OTI).

OBJETIVE

To determine the validity of quantitative measurement of oxygen debt (DEOx) according to arterial gases compared to the use of iROX in patients with high-flow nasal cannula (HFNC) therapy requirement, presenting with acute respiratory failure as a consequence of SARS-CoV-2 infection. In addition, we aimed to identify the factors associated with the need for orotracheal intubation (OTI).

METHODS

A retrospective observational cohort study of a database collected from patients with SARS-CoV-2 infection admitted to intensive care units with AHRF and had received HFNC upon admission during the Covid-19 pandemic (March 23, 2020 through August 02, 2021). The variables of interest were factors determining the predictive ability of DEOx and iROX. We used a multiple logarithmic regression model to correct for confounding and mixed-effects variables, and validated for OTI in patients treated with HFNC.

RESULTS

From a total of 373 patients treated with HFNC, 317 patients (84.9%) required invasive mechanical ventilation. APACHE II (AOR 1.44; 95% CI: 1.14-1.83, p 0,032), vasopressor use (AOR 27.7; 95% CI: 1.83 - 420,63, p 0,017), and DEOx (AOR 1.26; 95% CI: 1.10 - 1.44, p 0,001) were associated with the need for intubation. The predictive model between iROX and DEOx evidenced an AUC of 0.535 vs. 0.606, respectively, with a DEOx cut off point of 7.14 (±10.16, p < 0.01). DEOx as an independent factor of OTI presents an OR 2,48 with cut point 4.5 mlO2/kg (AUC 0.780, CI 95%, 0.753 - 0.808, p < 0.01).

CONCLUSIONS

DEOx is a valuable measurment to identify the need for OTI in patients with SARS-CoV-2 who were under management with HFNC with a predictive value superior to iROX, being a reproducible and valid quantitative method for the need OTI that can be implemented in other critically illconditions. Further studies are required to characterize the usefulness of DEOx more precisely.

Damage Control Surgery and Transfer in Emergency General Surgery

Selective non traumatic emergency surgery patients are targets for damage control surgery (DCS) to prevent or treat abdominal compartment syndrome and the lethal triad. However, DCS is still a subject of controversy. As a concept, DCS describes a series of abbreviated surgical procedures to allow rapid source control of hemorrhage and contamination in patients with circulatory shock to allow resuscitation and stabilization in the intensive care unit followed by delayed return to the operating room for definitive surgical management once the patient becomes physiologic stable. If appropriately applied, the DCS morbidity and mortality can be significantly reduced.

Prooxidant effects of high dose ascorbic acid administration on biochemical, haematological and histological changes in Cavia porcellus (Guinea pigs): a Guinea pig experimental model

Introduction

Ascorbic acid (AA) is a water-soluble vitamin that is well known for its antioxidant and immune-boosting properties. Owing to the wide-range application of AA in the treatment of numerous ailments and its sweet taste, it is usually abused i.e. overused. However, the effect of the abuse has rarely received attention. Therefore, this study was designed to assess the effect of oral administration of high-dose ascorbic acid on biochemical and haematological parameters as well as the effects on the kidney, liver and lungs.

Methods

adult guinea pigs were divided into four (4) groups where group 1 served as the untreated control group and groups 2-4 were dosed with 29 mg, 662 mg and 1258 mg of ascorbic acid per day, respectively for 28 days.

Results

the result revealed that administration of high dose ascorbic acid significantly (P<0.05) increased serum creatinine from 50.0 ± 7.09 (NC) to AA29- 73.8 ± 4.5, AA-662-89.7 ± 3.3 and AA1258- 79.9 ± 5.7mmol/L and urea levels in the treatment group AA-1258 -18.3 ± 0.5 µmol/L compared to the normal group (NC-2.15 ± 0.6 µmol/L). Disturbance in electrolyte balance was observed with a significant (P<0.05) increase in Na+ from NC- 131.3 ± 3.5 mmol/L to 135.7 ± 3.6 mmol/L in the AA-1258 treatment group, Cl- ( NC- 67.1 ± 1.6 mmol/L increased to AA29- 92.1 ± 0.83, AA662- 95.3 ± 1.3 and AA-1258- 95.6 ± 0.4 mmol/L), and Ca2+ (NC- 2.66 ± 0.03 to AA1258- 3.36 ± 0.03 mmol/L) and a significant (P<0.05) decrease in serum K+ in the AA29-5.0 ± 0.2, AA662-5.2 ± 0.3 and AA1258-5.6 ± 0.3 mmol/L treatment groups compared to the normal group 6.6 ± 0.3 mmol/L. There was also a significant (P<0.05) increase in the differential blood count in the animals with a significant (P<0.05) increase in red blood count ( NC-5.11 ± 0.13 ×106/µL to AA1258- 5.75 ± 0.11×106/µL ), haematocrit count (NC 39.90 ± 0.52% to AA-29-42.08 ± 0.24 and AA1258-46.13 ± 0.86%), white blood count (NC 10.15 ± 1.01 ×103/µL to AA1258- 15.18 ± 1.65×103/µL ), total lymphocytes (NC 3.5 ± 0.51×103/µL to AA29-5.28 ±0.43×103/µL), monocytes (NC 0.45 ± 0.07×103/µL to AA1258 0.80 ± 0.07×103/µL), eosinophils (NC 0.23 ± 0.03×103/µL to AA12580.40 ± 0.03×103/µL), basophils (NC0.68 ± 0.10×103/µL to AA12581.20 ± 0.10×103/µL) and neutrophil count (NC 4.73 ± 0.68×103/µL to AA1258 8.36 ± 0.71×103/µL). The histopathological indices indicate cellular necrosis in the AA662 and AA1258 treatment groups of the kidney and liver respectively compared to the normal control which has normal cells.

Conclusion

high dose of ascorbic acid can therefore be suggested to cause damage to the cells by causing cellular necrosis as observed in the histopathology results and has effect on the blood cells as observed in the increase compared to the normal control, and the consequences are possibly triggered through inflammatory responses.

Silk Fibroin Particles as Carriers in the Development of Hemoglobin-Based Oxygen Carriers

Oxygen therapeutics have a range of applications in transfusion medicine and disease treatment. Synthetic molecules and all-natural or semi-synthetic hemoglobin-based oxygen carriers (HBOCs) have seen success as potential circulating oxygen carriers. However, many early HBOC products stalled in development due to side effects from excess hemoglobin in the blood stream and hemoglobin entering the tissue. To overcome these issues, research has focused on increasing the molecular diameter of hemoglobin by polymerizing hemoglobin molecules or encapsulating hemoglobin in liposomal carriers. This work leverages the properties of silk fibroin, a cytocompatible and non-thrombogenic biopolymer, known to entrap protein-based cargo, to engineer a fully protein-based oxygen carrier. Herein, an all-aqueous solvent evaporation technique was used to form silk particles via phase separation from a bulk polyvinyl alcohol phase (PVA). Particles size was tuned, and particles were formed with and without hemoglobin. The encapsulation efficiency and ferrous state of hemoglobin were analyzed, resulting in 60% encapsulation efficiency and a maximum of 20% ferric hemoglobin, yielding 100 µg/mL active hemoglobin in certain sfHBOC formulations. The system did not elicit a strong inflammation response in vitro, demonstrating the potential for this particle system to serve as an injectable HBOC.

Mobile blood depots in ground ambulances in compliance with French legislation: A feasibility study

BACKGROUND

Prehospital transfusion is a way of improving the management of hemorrhagic shock. In France, prehospital transfusion is struggling to develop, both because of logistical difficulties and particularly restrictive legislation. To comply with this, we propose to store the blood products (BPs) in ground ambulances with refrigerated boxes allowing remote continuous monitoring of storage conditions, called "NelumBox" (Tec4med Lifescience GmbH). To open them, the ambulance's team needs a code that is only given by the Transfusion Center if the request meets all required regulatory criteria.

STUDY DESIGN AND METHODS

We conducted a prospective simulation-based feasibility study using dummy BPs. Two ambulances were equipped. Simulations were triggered unexpectedly, including during on-call hours. The ability to quickly access the BPs was the main judgment criterion. The quality of hemovigilance during these simulations was also examined.

RESULTS

Twenty-two simulations were performed. The ambulance's team was able to access the BPs in 100% of cases. The average waiting time for receiving the unlocking code was 5 min 27 s (SD = 2 min 12 s, MAX = 12 min 00 s). The transfusion traceability was compliant with regulations in 100% of cases. The transfusion center was able to remotely monitor BPs storage conditions for the entire duration of their stockage in the NelumBox.

DISCUSSION

The present procedure is efficient, repeatable, and fast. It guarantees a strict transfusion safety without slowdown a severe trauma management, while complying with French regulations.

Traumatic hemorrhage and chain of survival

Trauma is the number one cause of death among Americans between the ages of 1 and 46 years, costing more than $670 billion a year. Following death related to central nervous system injury, hemorrhage accounts for the majority of remaining traumatic fatalities. Among those with severe trauma that reach the hospital alive, many may survive if the hemorrhage and traumatic injuries are diagnosed and adequately treated in a timely fashion. This article aims to review the recent advances in pathophysiology management following a traumatic hemorrhage as well as the role of diagnostic imaging in identifying the source of hemorrhage. The principles of damage control resuscitation and damage control surgery are also discussed. The chain of survival for severe hemorrhage begins with primary prevention; however, once trauma has occurred, prehospital interventions and hospital care with early injury recognition, resuscitation, definitive hemostasis, and achieving endpoints of resuscitation become paramount. An algorithm is proposed for achieving these goals in a timely fashion as the median time from onset of hemorrhagic shock and death is 2 h.

Microcirculatory effects of rewarming in experimental hemorrhagic shock

BACKGROUND

Rewarming is a recommended therapy during the resuscitation of hypothermic patients with hemorrhagic shock. In experimental models, however, it increases inflammatory response and mortality. Although microcirculation is potential target of inflammation, the microvascular effects of rewarming during the resuscitation of hemorrhagic shock have not been studied. Our goal was to assess the systemic and microcirculatory effects of an increase in core temperature (T°) during the retransfusion of hemorrhagic shock in sheep. Our hypothesis was that rewarming could hamper microcirculation.

METHODS

In anesthetized and mechanically ventilated sheep, we measured systemic, intestinal, and renal hemodynamics and oxygen transport. O₂ consumption (VO₂) and respiratory quotient were measured by indirect calorimetry. Cortical renal, intestinal villi and sublingual microcirculation were assessed by IDF-videomicroscopy. After basal measurements, hemorrhagic shock was induced and T° was reduced to ~33 °C. After 1 h of shock and hypothermia, blood was retransfused and Ringer lactate solution was administered to prevent arterial hypotension. In the control group (n = 12), T° was not modified, while in the intervention (rewarming) group, it was elevated ~3 °C. Measurements were repeated after 1 h.

RESULTS

During shock, both groups showed similar systemic and microvascular derangements. After retransfusion, VO₂ remained decreased compared to baseline in both groups, but was lower in the control compared to the rewarming group. Perfused vascular density has a similar behavior in both groups. Compared to baseline, it remained reduced in peritubular (control vs. rewarming group, 13.8 [8.7-17.5] vs. 15.7 [10.1-17.9] mm/mm², PNS) and villi capillaries (14.7 [13.6-16.8] vs. 16.3 [14.2-16.9] mm/mm², PNS), and normalized in sublingual mucosa (19.1 [16.0-20.3] vs. 16.6 [14.7-17.2] mm/mm², PNS).

CONCLUSIONS

This is the first experimental study assessing the effect of rewarming on systemic, regional, and microcirculatory perfusion in hypothermic hemorrhagic shock. We found that a 3 °C increase in T° neither improved nor impaired the microvascular alterations that persisted after retransfusion. In addition, sublingual mucosa was less susceptible to reperfusion injury than villi and renal microcirculation.

"Stabilize the Unstable": Treatment Pathophysiology in Bleeding Trauma Patients, from the Field to the ICU. State of the Art

The results of the Global Burden of Disease (GBD) study showed that, in 2019, 8% of deaths worldwide were trauma related [...].

Effects of Seawater Immersion on Lethal Triad and Organ Function in Healthy and Hemorrhagic Shock Rats

INTRODUCTION

Marine casualties are increasing, and mortality from trauma associated with immersion in seawater is high. However, the associated pathophysiological characteristics remain unclear, limiting research into the early emergency treatment strategy.

METHODS

Healthy and 50% hemorrhagic shock rats were soaked in 15°C and 21°C seawater for 2 h, 4 h and 6 h, respectively, and the effects on vital signs, internal environment, tissue metabolism, lethal triad, vital organ functions and survival were observed.

RESULTS

Immersion in seawater can cause death in healthy rats. Rats with hemorrhagic shock in 15°C seawater showed a lower survival rate than the corresponding groups in 21°C seawater. Moreover, compared with 21°C seawater, 15°C seawater played a more remarkable role in decreasing mean arterial pressure, heart rate, and respiration rate, increasing water content and decreasing Na⁺/K⁺-ATPase activity in the brain and lung; increase in plasma osmolality, Na⁺, K⁺, Cl^-, and the occurrence of the lethal triad manifested by a decrease in core body temperature, pH, lactate, and an increase in coagulation parameters, as well as damage to cardiac, intestinal, hepatic, and renal functions in rats with hemorrhagic shock.

CONCLUSIONS

Immersion in seawater at low temperatures could be lethal to healthy rats, causing the occurrence of a lethal triad and damage to vital organs. Furthermore, 15°C-seawater had a more significant effect than 21°C-seawater on aggravating the imbalance of internal environment and tissue metabolism, resulting in a higher incidence of the lethal triad and thus aggravating the dysfunctions of vital organs, which eventually resulted in higher mortality in rats with hemorrhagic shock.

Adherence to a Balanced Approach to Massive Transfusion in Combat Casualties

BACKGROUND

Hemorrhage is the most common cause of potentially preventable death on the battlefield. Balanced resuscitation with plasma, platelets, and packed red blood cells (PRBCs) in a 1:1:1 ratio, if whole blood (WB) is not available, is associated with optimal outcomes among patients with hemorrhage. We describe the use of balanced resuscitation among combat casualties undergoing massive transfusion.

MATERIALS AND METHODS

We conducted a secondary analysis of data from the Department of Defense Trauma Registry (DODTR) spanning encounters from January 1, 2007, to March 17, 2020. We included all casualties who received at least 10 units of either PRBCs or WB. We categorized casualties as recipients of plasma-balanced resuscitation if the ratio of plasma to PRBC units was 0.8 or greater; similarly, we defined platelet-balanced resuscitation as a ratio of platelets to PRBC units of 0.8 or greater. We portrayed these populations using descriptive statistics and compared characteristics between non-balanced and balanced resuscitation recipients for both plasma and platelets.

RESULTS

We identified 28,950 encounters in the DODTR with documentation of prehospital activity. Massive transfusions occurred for 2,414 (8.3%) casualties, among whom 1,593 (66.0%) received a plasma-balanced resuscitation and 1,248 (51.7%) received a platelet-balanced resuscitation. During the study period, 962 (39.8%) of these patients received a fully balanced resuscitation with regard to both the plasma:PRBC and platelet:PRBC ratios. The remaining casualties did not undergo a balanced resuscitation.

CONCLUSIONS

While a majority of massive transfusion recipients received a plasma-balanced and/or platelet-balanced resuscitation, fewer patients received a platelet-balanced resuscitation. These findings suggest that more emphasis in training and supply may be necessary to optimize blood product resuscitation ratios.

Not all Shock States Are Created Equal: A Review of the Diagnosis and Management of Septic, Hypovolemic, Cardiogenic, Obstructive, and Distributive Shock

Shock in the critically ill patient is common and associated with poor outcomes. Categories include distributive, hypovolemic, obstructive, and cardiogenic, of which distributive (and usually septic distributive) shock is by far the most common. Clinical history, physical examination, and hemodynamic assessments & monitoring help differentiate these states. Specific management necessitates interventions to correct the triggering etiology as well as ongoing resuscitation to maintain physiologic milieu. One shock state may convert to another and may have an undifferentiated presentation; therefore, continual re-assessment is essential. This review provides guidance for intensivists for management of all shock states based on available scientific evidence.

Endothelial Cell Phenotypes Demonstrate Different Metabolic Patterns and Predict Mortality in Trauma Patients

In trauma patients, shock-induced endotheliopathy (SHINE) is associated with a poor prognosis. We have previously identified four metabolic phenotypes in a small cohort of trauma patients (N = 20) and displayed the intracellular metabolic profile of the endothelial cell by integrating quantified plasma metabolomic profiles into a genome-scale metabolic model (iEC-GEM). A retrospective observational study of 99 trauma patients admitted to a Level 1 Trauma Center. Mass spectrometry was conducted on admission samples of plasma metabolites. Quantified metabolites were analyzed by computational network analysis of the iEC-GEM. Four plasma metabolic phenotypes (A-D) were identified, of which phenotype D was associated with an increased injury severity score (p < 0.001); 90% (91.6%) of the patients who died within 72 h possessed this phenotype. The inferred EC metabolic patterns were found to be different between phenotype A and D. Phenotype D was unable to maintain adequate redox homeostasis. We confirm that trauma patients presented four metabolic phenotypes at admission. Phenotype D was associated with increased mortality. Different EC metabolic patterns were identified between phenotypes A and D, and the inability to maintain adequate redox balance may be linked to the high mortality.

Resuscitation with whole blood or blood components improves survival and lessens the pathophysiological burden of trauma and haemorrhagic shock in a pre-clinical porcine model

PURPOSE

In military trauma, disaster medicine, and casualties injured in remote locations, times to advanced medical and surgical treatment are often prolonged, potentially reducing survival and increasing morbidity. Since resuscitation with blood/blood components improves survival over short pre-surgical times, this study aimed to evaluate the quality of resuscitation afforded by blood/blood products or crystalloid resuscitation over extended 'pre-hospital' timelines in a porcine model of militarily relevant traumatic haemorrhagic shock.

METHODS

This study underwent local ethical review and was done under the authority of Animals (Scientific Procedures) Act 1986. Forty-five terminally anaesthetised pigs received a soft tissue injury to the right thigh, haemorrhage (30% blood volume and a Grade IV liver injury) and fluid resuscitation initiated 30 min later [Group 1 (no fluid); 2 (0.9% saline); 3 (1:1 packed red blood cells:plasma); 4 (fresh whole blood); or 5 (plasma)]. Fluid (3 ml/kg bolus) was administered during the resuscitation period (maximum duration 450 min) when the systolic blood pressure fell below 80 mmHg. Surviving animals were culled with an overdose of anaesthetic.

RESULTS

Survival time was significantly shorter for Group 1 compared to the other groups (P < 0.05). Despite the same triggers for resuscitation when compared to blood/blood components, saline was associated with a shorter survival time (P = 0.145), greater pathophysiological burden and significantly greater resuscitation fluid volume (P < 0.0001).

CONCLUSION

When times to advanced medical care are prolonged, resuscitation with blood/blood components is recommended over saline due to the superior quality and stability of resuscitation achieved, which are likely to lead to improved patient outcomes.

An Automated Hardware-in-Loop Testbed for Evaluating Hemorrhagic Shock Resuscitation Controllers

Hemorrhage remains a leading cause of death, with early goal-directed fluid resuscitation being a pillar of mortality prevention. While closed-loop resuscitation can potentially benefit this effort, development of these systems is resource-intensive, making it a challenge to compare infusion controllers and respective hardware within a range of physiologically relevant hemorrhage scenarios. Here, we present a hardware-in-loop automated testbed for resuscitation controllers (HATRC) that provides a simple yet robust methodology to evaluate controllers. HATRC is a flow-loop benchtop system comprised of multiple PhysioVessels which mimic pressure-volume responsiveness for different resuscitation infusates. Subject variability and infusate switching were integrated for more complex testing. Further, HATRC can modulate fluidic resistance to mimic arterial resistance changes after vasopressor administration. Finally, all outflow rates are computer-controlled, with rules to dictate hemorrhage, clotting, and urine rates. Using HATRC, we evaluated a decision-table controller at two sampling rates with different hemorrhage scenarios. HATRC allows quantification of twelve performance metrics for each controller configuration and scenario, producing heterogeneous results and highlighting the need for controller evaluation with multiple hemorrhage scenarios. In conclusion, HATRC can be used to evaluate closed-loop controllers through user-defined hemorrhage scenarios while rating their performance. Extensive controller troubleshooting using HATRC can accelerate product development and subsequent translation.

Evaluation of a Proportional-Integral-Derivative Controller for Hemorrhage Resuscitation Using a Hardware-in-Loop Test Platform

Hemorrhage is a leading cause of preventable death in trauma, which can often be avoided with proper fluid resuscitation. Fluid administration can be cognitive-demanding for medical personnel as the rates and volumes must be personalized to the trauma due to variations in injury severity and overall fluid responsiveness. Thus, automated fluid administration systems are ideal to simplify hemorrhagic shock resuscitation if properly designed for a wide range of hemorrhage scenarios. Here, we highlight the development of a proportional-integral-derivative (PID) controller using a hardware-in-loop test platform. The controller relies only on an input data stream of arterial pressure and a target pressure; the PID controller then outputs infusion rates to stabilize the subject. To evaluate PID controller performance with more than 10 controller metrics, the hardware-in-loop platform allowed for 11 different trauma-relevant hemorrhage scenarios for the controller to resuscitate against. Overall, the two controller configurations performed uniquely for the scenarios, with one reaching the target quicker but often overshooting, while the other rarely overshot the target but failed to reach the target during severe hemorrhage. In conclusion, PID controllers have the potential to simplify hemorrhage resuscitation if properly designed and evaluated, which can be accomplished with the test platform shown here.

Exploratory Investigation of the Plasma Proteome Associated with the Endotheliopathy of Trauma

BACKGROUND

The endotheliopathy of trauma (EoT) is associated with increased mortality following injury. Herein, we describe the plasma proteome related to EoT in order to provide insight into the role of the endothelium within the systemic response to trauma.

METHODS

99 subjects requiring the highest level of trauma activation were included in the study. Enzyme-linked immunosorbent assays of endothelial and catecholamine biomarkers were performed on admission plasma samples, as well as untargeted proteome quantification utilizing high-performance liquid chromatography and tandem mass spectrometry.

RESULTS

Plasma endothelial and catecholamine biomarker abundance was elevated in EoT. Patients with EoT (n = 62) had an increased incidence of death within 24 h at 21% compared to 3% for non-EoT (n = 37). Proteomic analysis revealed that 52 out of 290 proteins were differentially expressed between the EoT and non-EoT groups. These proteins are involved in endothelial activation, coagulation, inflammation, and oxidative stress, and include known damage-associated molecular patterns (DAMPs) and intracellular proteins specific to several organs.

CONCLUSIONS

We report a proteomic profile of EoT suggestive of a surge of DAMPs and inflammation driving nonspecific activation of the endothelial, coagulation, and complement systems with subsequent end-organ damage and poor clinical outcome. These findings support the utility of EoT as an index of cellular injury and delineate protein candidates for therapeutic intervention.

A simple and novel equation to estimate the degree of bleeding in haemorrhagic shock: mathematical derivation and preliminary in vivo validation

Determining blood loss [100% – RBV (%)] is challenging in the management of haemorrhagic shock. We derived an equation estimating RBV (%) via serial haematocrits (Hct₁, Hct₂) by fixing infused crystalloid fluid volume (N) as [0.015 × body weight (g)]. Then, we validated it in vivo. Mathematically, the following estimation equation was derived: RBV (%) = 24k / [(Hct₁ / Hct₂) – 1]. For validation, non-ongoing haemorrhagic shock was induced in Sprague–Dawley rats by withdrawing 20.0%–60.0% of their total blood volume (TBV) in 5.0% intervals (n = 9). Hct₁ was checked after 10 min and normal saline N cc was infused over 10 min. Hct₂ was checked five minutes later. We applied a linear equation to explain RBV (%) with 1 / [(Hct₁ / Hct₂) – 1]. Seven rats losing 30.0%–60.0% of their TBV suffered shock persistently. For them, RBV (%) was updated as 5.67 / [(Hct₁ / Hct₂) – 1] + 32.8 (95% confidence interval [CI] of the slope: 3.14–8.21, p = 0.002, R² = 0.87). On a Bland-Altman plot, the difference between the estimated and actual RBV was 0.00 ± 4.03%; the 95% CIs of the limits of agreements were included within the pre-determined criterion of validation (< 20%). For rats suffering from persistent, non-ongoing haemorrhagic shock, we derived and validated a simple equation estimating RBV (%). This enables the calculation of blood loss via information on serial haematocrits under a fixed N. Clinical validation is required before utilisation for emergency care of haemorrhagic shock.

Targeting repair of the vascular endothelium and glycocalyx after traumatic injury with plasma and platelet resuscitation

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Endothelial glycocalyx shedding is a key instigator of the endotheliopathy of trauma.

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Plasma and platelet transfusions preserve vascular integrity in pre-clinical models.

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However, platelets may be less effective than plasma in preserving the glycocalyx.

Severely injured patients with hemorrhagic shock can develop endothelial dysfunction, systemic inflammation, and coagulation disturbances collectively known as the endotheliopathy of trauma (EOT). Shedding of the endothelial glycocalyx occurs early after injury, contributes to breakdown of the vascular barrier, and plays a critical role in the pathogenesis of multiple organ dysfunction, leading to poor outcomes in trauma patients. In this review we discuss (i) the pathophysiology of endothelial glycocalyx and vascular barrier breakdown following hemorrhagic shock and trauma, and (ii) the role of plasma and platelet transfusion in maintaining the glycocalyx and vascular endothelial integrity.

Training trial of critical care paramedics for non-medical authorisation of blood

The use of pre-hospital blood transfusion by air ambulance crews is increasing. Blood transfusion is traditionally ‘authorised’ by doctors, not prescribed. However, there is an increasing interest in extending the capability of authorisation to other practitioners – that is, non-medical authorisation (NMA). A UK framework for nurses and midwives has existed since 2007, but training for critical care paramedics (CCPs) has been limited.

The Resuscitation with Pre-Hospital Blood Products (RePHILL) trial was launched in 2016, requiring pre-hospital administration of red cells and LyoPlas. Authorisation was initially restricted to doctors, leading to missed recruitment by paramedic-only crews. The trial protocol was amended in 2019 to permit NMA following suitable training and stakeholder consultation. We present a targeted training programme designed to support paramedic-led transfusion within the framework of the pre-hospital trial.

We considered the knowledge and skills required for NMA and compared this with baseline knowledge from paramedic training to identify the training gap. We examined examples of existing military and civilian NMA training to develop a targeted programme for a single air ambulance. The four elements of our training programme were pre-course online training, previous trial participation, face-to-face training and competency assessment.

Training was delivered to three CCPs, who cascaded the training to 14 colleagues. The training time was one morning, including a face-to-face session and assessment. Novel topics included physiological triggers for transfusion and transfusion risks in the pre-hospital environment. Paramedics were encouraged to recognise and report new patterns of adverse events. Reflective feedback suggests the programme provided CCPs the knowledge to autonomously recruit trial patients and authorise transfusion.

Protective Effect of Shenfu Injection () on Vascular Endothelial Damage in a Porcine Model of Hemorrhagic Shock

OBJECTIVE

To investigate the effects of Shenfu Injection (, SFI) on endothelial damage in a porcine model of hemorrhagic shock (HS).

METHODS

After being bled to a mean arterial pressure of 40±3 mm Hg and held for 60 min, 32 pigs were treated with a venous injection of either shed blood (transfusion group), shed blood and saline (saline group), shed blood and SFI (SFI group) or without resuscitation (sham group). Venous blood samples were collected and analyzed at baseline and 0, 1, 2, 4, and 6 h after HS. Tumor necrosis factor-α (TNF-α), serum interleuking (IL)-6, and IL-10 levels were measured by enzyme-linked immunosorbent assay (ELISA); expressions of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule 1 (ICAM -1), von Willebrand factor (vWF), plasminogen activator inhibitor-1 (PAI-1) and Bcl-2, Bax, and caspase-3 proteins were determined by Western blot.

RESULTS

The serum level of TNF-α in the SFI group was significantly lower than in the other groups at 0, 1, and 2 h after HS, while the level of IL-6 was lower at 4 and 6 h compared with the saline group (P<0.01 or P<0.05). The concentration of serum IL-10 was significantly higher in the SFI group than in the other groups at 0, 1, 4, and 6 h after HS (P<0.01). Western blot and immunohistochemistry of vascular tissue showed that the expression of caspase-3 was downregulated, and that of Bcl-2 and Bax was upregulated in the SFI group compared to other groups (P<0.05).

CONCLUSION

SFI attenuated endothelial injury in the porcine model of HS by inhibiting cell apoptosis, suppressing the formation of proinflammatory cytokines, and reducing endothelial activation.

Pathophysiology of Hemorrhage as It Relates to the Warfighter

Saving lives of wounded military Warfighters often depends on the ability to resolve or mitigate the pathophysiology of hemorrhage, specifically diminished oxygen delivery to vital organs that leads to multi-organ failure and death. However, caring for hemorrhaging patients on the battlefield presents unique challenges that extend beyond applying a tourniquet and giving a blood transfusion, especially when battlefield care must be provided for a prolonged period. This review will describe these challenges and potential strategies for treating hemorrhage on the battlefield in a prolonged casualty care situation.

Anticoagulation targeting membrane-bound anionic phospholipids improves outcomes of traumatic brain injury in mice

Severe traumatic brain injury (TBI) often causes an acute systemic hypercoagulable state that rapidly develops into consumptive coagulopathy. We have recently demonstrated that TBI-induced coagulopathy (TBI-IC) is initiated and disseminated by brain-derived extracellular vesicles (BDEVs) and propagated by extracellular vesicles (EVs) from endothelial cells and platelets. Here, we present results from a study designed to test the hypothesis that anticoagulation targeting anionic phospholipid-expressing EVs prevents TBI-IC and improves the outcomes of mice subjected to severe TBI. We evaluated the effects of a fusion protein (ANV-6L15) for improving the outcomes of TBI in mouse models combined with in vitro experiments. ANV-6L15 combines the phosphatidylserine (PS)-binding annexin V (ANV) with a peptide anticoagulant modified to preferentially target extrinsic coagulation. We found that ANV-6L15 reduced intracranial hematoma by 70.2%, improved neurological function, and reduced death by 56.8% in mice subjected to fluid percussion injury at 1.9 atm. It protected the TBI mice by preventing vascular leakage, tissue edema, and the TBI-induced hypercoagulable state. We further showed that the extrinsic tenase complex was formed on the surfaces of circulating EVs, with the highest level found on BDEVs. The phospholipidomic analysis detected the highest levels of PS on BDEVs, as compared with EVs from endothelial cells and platelets (79.1, 15.2, and 3.5 nM/mg of protein, respectively). These findings demonstrate that TBI-IC results from a trauma-induced hypercoagulable state and may be treated by anticoagulation targeting on the anionic phospholipid-expressing membrane of EVs from the brain and other cells.

Plasma components to protect the endothelial barrier after shock: A role for sphingosine 1-phosphate

BACKGROUND

Hemorrhagic shock leads to endothelial glycocalyx shedding, endothelial cellular inflammation, and increased vascular permeability. Early plasma administration improves survival in severely injured patients; this may be due in part to its ability to ameliorate this trauma-induced endotheliopathy. The protective effect of early plasma administration may be due to its sphingosine 1-phosphate content. Principle carriers of plasma sphingosine 1-phosphate include apolipoprotein M and albumin. The relative roles of these carriers on sphingosine 1-phosphate protective effects are unknown and were studied in an in vitro model of microcirculation.

METHODS

Endothelial cell monolayers were established in microfluidic perfusion devices and exposed to control or biomimetic shock conditions. Sphingosine 1-phosphate, albumin + sphingosine 1-phosphate, or apolipoprotein M + sphingosine 1-phosphate were added later to the perfusate. Biomarkers of endothelial and glycocalyx activation and damage were then determined.

RESULTS

Sphingosine 1-phosphate preserved endothelial and glycocalyx barrier function after exposure to conditions of shock in the microcirculation. The protective effect was related to sphingosine 1-phosphate chaperones; the apolipoprotein M loaded with sphingosine 1-phosphate had the most profound effect.

CONCLUSION

Carrier-based sphingosine 1-phosphate may be a useful adjunct in early hemorrhagic shock resuscitation.

High-Fructose Diet Alters Intestinal Microbial Profile and Correlates with Early Tumorigenesis in a Mouse Model of Barrett’s Esophagus

Esophageal adenocarcinoma (EAC) is mostly prevalent in industrialized countries and has been associated with obesity, commonly linked with a diet rich in fat and refined sugars containing high fructose concentrations. In meta-organisms, dietary components are digested and metabolized by the host and its gut microbiota. Fructose has been shown to induce proliferation and cell growth in pancreas and colon cancer cell lines and also alter the gut microbiota. In a previous study with the L2-IL-1B mouse model, we showed that a high-fat diet (HFD) accelerated EAC progression from its precursor lesion Barrett’s esophagus (BE) through changes in the gut microbiota. Aiming to investigate whether a high-fructose diet (HFrD) also alters the gut microbiota and favors EAC carcinogenesis, we assessed the effects of HFrD on the phenotype and intestinal microbial communities of L2-IL1B mice. Results showed a moderate acceleration in histologic disease progression, a mild effect on the systemic inflammatory response, metabolic changes in the host, and a shift in the composition, metabolism, and functionality of intestinal microbial communities. We conclude that HFrD alters the overall balance of the gut microbiota and induces an acceleration in EAC progression in a less pronounced manner than HFD.

A Descriptive Analysis of Supermassive Transfusion Recipients Among US and Coalition Forces During Combat Operations in Afghanistan and Iraq

INTRODUCTION

Hemorrhage is the leading cause of potentially preventable death on the battlefield. Resuscitation with blood products is essential to restore circulating volume, repay the oxygen debt, and prevent coagulopathy. Massive transfusion (MT) occurs frequently after major trauma; a subset of casualties requires a supermassive transfusion (SMT), and thus, mobilization of additional resources remains unclear.

MATERIALS AND METHODS

This is a secondary analysis of a previously described dataset from the Department of Defense Trauma Registry. In this analysis, we isolated U.S. and Coalition casualties that received at least 1 unit of packed red blood cells (PRBCs) or whole blood (WB). Given a lack of consensus on the definition of SMT recipients, we included those patients receiving the top quartile of PRBC and WB administered within the first 24 hours following arrival to a military treatment facility.

RESULTS

We identified 25,897 adult casualties from January 1, 2007 to March 17, 2020. Within this dataset, 2,608 (9.0%) met inclusion for this analysis. The median number of total products administered within the first 24 hours was 8 units of PRBC or WB. The upper quartile was 18 units (n = 666). Compared to all other blood product recipients, patients in the SMT cohort had a higher median injury severity score (27 vs 18, P < 0.001), were most frequently injured by explosives (84.9% vs 68.6%, P < 0.001), had a higher mean emergency department (ED) pulse (128 vs 111, P < 0.001), a lower mean systolic blood pressure (122 vs 132 mm Hg, P < 0.001), and a higher mean international normalized ratio (1.68 vs 1.38, P < 0.001). SMT patients experienced lower survival to hospital discharge (85.8% vs 93.3%, P < 0.001).

CONCLUSIONS

Compared to all other PRBC and WB recipients, SMT patients experienced more injury by explosives, severe injury patterns, ED vital sign derangements, and mortality. These findings may help identify those casualties who may require earlier aggressive resuscitation. However, more data is needed to define this population early in their clinical course for early identification to facilitate rapid resource mobilization. Identifying casualties who are likely to die within 24 hours compared to those who are likely to survive, may assist in determining a threshold for a SMT.

Therapeutic Potential of Mesenchymal Stromal Cell-Derived Extracellular Vesicles in the Prevention of Organ Injuries Induced by Traumatic Hemorrhagic Shock

Severe trauma is the principal cause of death among young people worldwide. Hemorrhagic shock is the leading cause of death after severe trauma. Traumatic hemorrhagic shock (THS) is a complex phenomenon associating an absolute hypovolemia secondary to a sudden and significant extravascular blood loss, tissue injury, and, eventually, hypoxemia. These phenomena are responsible of secondary injuries such as coagulopathy, endotheliopathy, microcirculation failure, inflammation, and immune activation. Collectively, these dysfunctions lead to secondary organ failures and multi-organ failure (MOF). The development of MOF after severe trauma is one of the leading causes of morbidity and mortality, where immunological dysfunction plays a central role. Damage-associated molecular patterns induce an early and exaggerated activation of innate immunity and a suppression of adaptive immunity. Severe complications are associated with a prolonged and dysregulated immune–inflammatory state. The current challenge in the management of THS patients is preventing organ injury, which currently has no etiological treatment available. Modulating the immune response is a potential therapeutic strategy for preventing the complications of THS. Mesenchymal stromal cells (MSCs) are multipotent cells found in a large number of adult tissues and used in clinical practice as therapeutic agents for immunomodulation and tissue repair. There is growing evidence that their efficiency is mainly attributed to the secretion of a wide range of bioactive molecules and extracellular vesicles (EVs). Indeed, different experimental studies revealed that MSC-derived EVs (MSC-EVs) could modulate local and systemic deleterious immune response. Therefore, these new cell-free therapeutic products, easily stored and available immediately, represent a tremendous opportunity in the emergency context of shock. In this review, the pathophysiological environment of THS and, in particular, the crosstalk between the immune system and organ function are described. The potential therapeutic benefits of MSCs or their EVs in treating THS are discussed based on the current knowledge. Understanding the key mechanisms of immune deregulation leading to organ damage is a crucial element in order to optimize the preparation of EVs and potentiate their therapeutic effect.

Evaluation of hemostatic capacities among commando candidates: Would their blood suit a hemorrhagic war-injured patient in case of blood donation on the battlefield?

BACKGROUND

In case of a warm fresh whole blood transfusion on the battlefield, the blood donation usually occurs just after a combat phase and often after several days on the fields. To explore the hemostatic capacity of such blood, we analyzed the blood of volunteers attending the commando course of the French Navy, considering this course as an experimental model, placing them into the same physiological conditions as those faced by deployed fighters.

METHODS

Venous blood was collected at the beginning of the course, mimicking their baseline status, and a second time 6 weeks later, from the remaining candidates, during the actual commando training, mimicking the stress conditions. For each candidate, we observed the differences between the two blood samples.

RESULTS

Of the 112 men that attended the first day of the course, only 17 remained 6 weeks later. In the second blood samples, we noted significant increased leucocytes and platelets counts and significant decreased hematocrit and hemoglobin levels. Thrombin generation assays showed significantly lower normalized peak heights (-31%), lower normalized endogenous thrombin potential values (-29%), and lower velocity index (-35%). Normalized lag time and time to peak did not differ. Viscoelastometric testing revealed a significant increasing in clot firmness as assessed by maximum amplitude and amplitude at 6 minutes. The clot speed was significantly increased.

CONCLUSION

This work brings new data on coagulation during prolonged and considerable physical exercise. No obvious deleterious modification of hemostatic properties was observed. The decrease of the endogenous thrombin potentials may reflect a better ability to control the thrombin generation once started. Altogether, these results suggest that this blood could suit well a hemorrhagic war-injured patient.

LEVEL OF EVIDENCE

Prospective observational cohort study, Level III.

Hemorrhagic shock and hemostatic resuscitation in canine trauma

Hemorrhage is a significant cause of death among military working dogs and in civilian canine trauma. While research specifically aimed at canine trauma is limited, many principles from human trauma resuscitation apply. Trauma with significant hemorrhage results in shock and inadequate oxygen delivery to tissues. This leads to aberrations in cellular metabolism, including anaerobic metabolism, decreased energy production, acidosis, cell swelling, and eventual cell death. Considering blood and endothelium as a single organ system, blood failure is a syndrome of endotheliopathy, coagulopathy, and platelet dysfunction. In severe cases following injury, blood failure develops and is induced by inadequate oxygen delivery in the presence of hemorrhage, tissue injury, and acute stress from trauma. Severe hemorrhagic shock is best treated with hemostatic resuscitation, wherein blood products are used to restore effective circulating volume and increase oxygen delivery to tissues without exacerbating blood failure. The principles of hemostatic resuscitation have been demonstrated in severely injured people and the authors propose an algorithm for applying this to canine patients. The use of plasma and whole blood to resuscitate severely injured canines while minimizing the use of crystalloids and colloids could prove instrumental in improving both mortality and morbidity. More work is needed to understand the canine patient that would benefit from hemostatic resuscitation, as well as to determine the optimal resuscitation strategy for these patients.

Spray-dried plasma: A post-traumatic blood "bridge" for life-saving resuscitation

Massive bleeding remains a major source of morbidity and mortality worldwide. Recent studies have shed light on the pathophysiology of traumatic-induced coagulopathy and the central role of endotheliopathy. Transfusion therapy has changed dramatically in the last decade with use of red cells and plasma in a 1:1 ratio. The use of early transfusion increases the likelihood of a favorable outcome. Early intervention-preferably less than 60 min of injury-is a major factor in improved survival. Experience with dried plasma products-lyophilized or freeze-dried-in Europe and South Africa has demonstrated both safety and efficacy. Dry plasma products are not available in the United States but several products are in development. Spray-dried plasma contains clinically meaningful levels of coagulation activity and in vitro data suggest robust ability to generate thrombus. The decentralized, blood-center based manufacturing model of spray-dried plasma offers advantages for availability to meet routine and extraordinary demands.

Macrocirculatory Parameters and Oxygen Debt Indices in Pigs During Propofol Or Alfaxalone Anesthesia When Subjected to Experimental Stepwise Hemorrhage

Background: Pigs are anesthetized when used for emergency procedures live tissue training (LTT) of civilian and military medical personnel or for experimental purposes, but there is a paucity in the literature regarding anesthesia of pigs for this purpose. Objective(s): The main goals of the study were to compare oxygen debt, macrocirculatory parameters, and time to cardiac arrest between pigs in hemorrhagic shock and anesthetized with propofol-ketamine-dexmedetomidine or alfaxalone-ketamine-dexmedetomidine. Design: A prospective, non-blinded randomized study design was used. Sixteen pigs were randomized in blocks of four to be anesthetized with either propofol-ketamine-dexmedetomidine (n = 8) or alfaxalone-ketamine-dexmedetomidine (n = 8) as a continuous infusion. Interventions: Premedication with ketamine 15 mg kg^-1 and midazolam 1 mg kg^-1 was given i.m. Anesthesia was maintained with propofol 8 mg kg^-1 h^-1 or alfaxalone 5 mg kg^-1 h^-1 combined with ketamine 5 mg kg^-1 h^-1 and dexmedetomidine 4 μg kg^-1 h^-1 i.v. A stepwise, volume-controlled model for hemorrhage was created by exsanguination. Main Outcome Measures: Indices of oxygen debt (lactate, base excess, and oxygen extraction), macrocirculatory (PR, SAP, DAP, MAP, and CI, SVI, and TPR) variables, and time to death was compared between groups. Results: Pigs in the alfaxalone group had significantly higher SAP than pigs given propofol. No difference in other macrocirculatory variables or indices of oxygen debt could be found. A blood loss of 50% of the total blood volume or more was possible in most pigs with both anesthetic regimes. Conclusions: Pigs anesthetized with propofol or alfaxalone combined with ketamine and dexmedetomidine tolerated substantial blood loss.

Effects of Systemic Hypothermia on Microcirculation in Conditions of Hemodynamic Stability and in Hemorrhagic Shock

INTRODUCTION

Although hypothermia is independently associated with an increased mortality in trauma patients, it might be an effective therapeutic approach for otherwise lethal hemorrhage. The effect of hypothermia on microcirculation, however, has been poorly studied in this setting. Our goal was to characterize the effects of hypothermia on microcirculation in normal conditions and in severe hemorrhagic shock.

METHODS

In anesthetized and mechanically ventilated sheep, we measured cardiac output (CO), renal blood flow (RBF), and systemic and renal O2 consumption (VO2). Cortical renal, intestinal villi, and sublingual microcirculation was assessed by IDF-videomicroscopy. After basal measurements, sheep were assigned to hypothermia (n = 12) and normothermia (n = 12) groups. Central temperature was reduced to ∼34°C and maintained at baseline in each group, respectively. Measurements were repeated after 1 h of hemodynamic stable conditions and 1 h of severe hemorrhagic shock.

RESULTS

In conditions of hemodynamic stability, the hypothermia group showed lower CO, RBF, and systemic and renal VO2 than the normothermia group. Red blood cell velocity was also lower in renal, villi, and sublingual microvascular beds (836 ± 195 vs. 1,066 ± 162, 916 ± 105 vs. 1051 ± 41, and 970 ± 182 vs. 1,102 ± 49 μm/s, respectively; P < 0.0001 for all). In hemorrhagic shock, most of the microvascular variables were similarly compromised in both the groups. In hypo- and normothermia groups, the percentage of reduction in perfused vascular density was higher in renal than in intestinal and sublingual microcirculation (66 ± 31 vs. 31 ± 23 and 15 ± 15%, and 78 ± 26 vs. 32 ± 37 and 18 ± 21%, P < 0.01 for both).

CONCLUSIONS

This is the first experimental study assessing the effect of systemic hypothermia on microcirculation in severe hemorrhagic shock. The main finding was that hypothermia did not hamper additionally the microcirculatory derangements induced by hemorrhagic shock. In addition, renal microcirculation was more susceptible to hemorrhagic shock than villi and sublingual microcirculation.

Hypocalcemia in Military Casualties From Point of Injury to Surgical Teams in Afghanistan

INTRODUCTION

Hypocalcemia is a known sequela of citrated blood product transfusion. Civilian data suggest hypocalcemia on hospital admission is associated with worse outcomes. Initial calcium levels in military casualties have not previously been analyzed. The objective of this retrospective review aimed to assess the initial calcium levels in military trauma casualties at different Forward Surgical Teams (FST) locations in Afghanistan and describe the effects of prehospital blood product administration on arrival calcium levels.

MATERIALS AND METHODS

This is a retrospective cohort analysis of military casualties arriving from point of injury to one of two FSTs in Afghanistan from August 2018 to February 2019 split into four locations. The primary outcome was incidence of hypocalcemia (ionized calcium < 1.20 mmol/L).

RESULTS

There were 101 patients included; 55 (54.5%) experienced hypocalcemia on arrival to the FST with a mean calcium of 1.16 mmol/L (95% confidence interval [CI], 1.14 to 1.18). The predominant mechanism of injury consisted of blast patterns, 46 (45.5%), which conferred an increased risk of hypocalcemia compared to all other patterns of injury (odds ratio = 2.42, P = .042). Thirty-eight (37.6%) patients required blood product transfusion. Thirty-three (86.8%) of the patients requiring blood product transfusion were hypocalcemic on arrival. Mean initial calcium of patients receiving blood product was 1.13 mmol/L (95% CI, 1.08 to 1.18), which was significantly lower than those who did not require transfusion (P = .01). Eight (7.9%) of the patients received blood products before arrival, with 6/8 (75%) presenting with hypocalcemia.

CONCLUSIONS

Hypocalcemia develops rapidly in military casualties and is prevalent on admission even before transfusion of citrated blood products. Blast injuries may confer an increased risk of developing hypocalcemia. This data support earlier use of calcium supplementation during resuscitation.

Physiology of Human Hemorrhage and Compensation

Hemorrhage is a leading cause of death following traumatic injuries in the United States. Much of the previous work in assessing the physiology and pathophysiology underlying blood loss has focused on descriptive measures of hemodynamic responses such as blood pressure, cardiac output, stroke volume, heart rate, and vascular resistance as indicators of changes in organ perfusion. More recent work has shifted the focus toward understanding mechanisms of compensation for reduced systemic delivery and cellular utilization of oxygen as a more comprehensive approach to understanding the complex physiologic changes that occur following and during blood loss. In this article, we begin with applying dimensional analysis for comparison of animal models, and progress to descriptions of various physiological consequences of hemorrhage. We then introduce the complementary side of compensation by detailing the complexity and integration of various compensatory mechanisms that are activated from the initiation of hemorrhage and serve to maintain adequate vital organ perfusion and hemodynamic stability in the scenario of reduced systemic delivery of oxygen until the onset of hemodynamic decompensation. New data are introduced that challenge legacy concepts related to mechanisms that underlie baroreflex functions and provide novel insights into the measurement of the integrated response of compensation to central hypovolemia known as the compensatory reserve. The impact of demographic and environmental factors on tolerance to hemorrhage is also reviewed. Finally, we describe how understanding the physiology of compensation can be translated to applications for early assessment of the clinical status and accurate triage of hypovolemic and hypotensive patients. © 2021 American Physiological Society. Compr Physiol 11:1531-1574, 2021.

Variations and obstacles in the use of coagulation factor concentrates for major trauma bleeding across Europe: outcomes from a European expert meeting

Purpose

Trauma is a leading cause of mortality, with major bleeding and trauma-induced coagulopathy (TIC) contributing to negative patient outcomes. Treatments for TIC include tranexamic acid (TXA), fresh frozen plasma (FFP), and coagulation factor concentrates (CFCs, e.g. prothrombin complex concentrates [PCCs] and fibrinogen concentrate [FCH]). Guidelines for TIC management vary across Europe and a clear definition of TIC is still lacking.

Methods

An advisory board involving European trauma experts was held on 02 February 2019, to discuss clinical experience in the management of trauma-related bleeding and recommendations from European guidelines, focusing on CFC use (mainly FCH). This review summarises the discussions, including TIC definitions, gaps in the guidelines that affect their implementation, and barriers to use of CFCs, with suggested solutions.

Results

A definition of TIC, which incorporates clinical (e.g. severe bleeding) and laboratory parameters (e.g. low fibrinogen) is suggested. TIC should be treated immediately with TXA and FCH/red blood cells; subsequently, if fibrinogen ≤ 1.5 g/L (or equivalent by viscoelastic testing), treatment with FCH, then PCC (if bleeding continues) is suggested. Fibrinogen concentrate, and not FFP, should be administered as first-line therapy for TIC. Several initiatives may improve TIC management, with improved medical education of major importance; generation of new and stronger data, simplified clinical practice guidance, and improved access to viscoelastic testing are also critical factors.

Conclusions

Management of TIC is challenging. A standard definition of TIC, together with initiatives to facilitate effective CFC administration, may contribute to improved patient care and outcomes.

Neglected No More: Emerging Cellular Therapies in Traumatic Injury

Traumatic injuries are a leading cause of death and disability in both military and civilian populations. Given the complexity and diversity of traumatic injuries, novel and individualized treatment strategies are required to optimize outcomes. Cellular therapies have potential benefit for the treatment of acute or chronic injuries, and various cell-based pharmaceuticals are currently being tested in preclinical studies or in clinical trials. Cellular therapeutics may have the ability to complement existing therapies, especially in restoring organ function lost due to tissue disruption, prolonged hypoxia or inflammatory damage. In this article we highlight the current status and discuss future directions of cellular therapies for the treatment of traumatic injury. Both published research and ongoing clinical trials are discussed here.

Massive Transfusion in Pediatric Patients

Massive transfusion in pediatric patients is infrequent but associated with much higher mortality than in adults. Blood transfusion and hematology has conceptualized ideas such as blood failure and the interplay of the blood-endothelium interface to understand coagulopathy in the context of hemorrhagic shock. Researchers are still searching for an appropriate definition of what constitutes a pediatric massive transfusion. There is no universally accepted protocol for massive transfusion and how to address the many complications that can arise. Pharmacologic adjuncts to resuscitation may prove beneficial in reducing coagulopathy during pediatric massive transfusion, but high-quality evidence has not yet emerged.

Diverse activities of von Willebrand factor in traumatic brain injury and associated coagulopathy

Traumatic brain injury (TBI) is a leading cause of death and disability. Patients with isolated TBI lose a limited amount of blood to primary injury, but they often develop secondary coagulopathy, resulting in delayed or recurrent intracranial and intracerebral hematoma. TBI-induced coagulopathy is closely associated with poor outcomes for these patients, including death. This secondary coagulopathy is consumptive in nature, involving not only brain-derived molecules, coagulation factors, and platelets, but also endothelial cells in a complex process now called blood failture. A key question is how a localized injury to the brain is rapidly disseminated to affect systemic hemostasis that is not directly affected the way it is in trauma to the body and limbs, especially with hemorrhagic shock. Increasing evidence suggests that the adhesive ligand von Willebrand factor (VWF), which is synthesized in and released from endothelial cells, plays a paradoxical role in both facilitating local hemostasis at the site of injury and also propagating TBI-induced endotheliopathy and coagulopathy systemically. This review discusses recent progress in understanding these diverse activities of VWF and the knowledge gaps in defining their roles in TBI and associated coagulopathy.

Resuscitation After Hemorrhagic Shock in the Microcirculation: Targeting Optimal Oxygen Delivery in the Design of Artificial Blood Substitutes

Microcirculatory preservation is essential for patient recovery from hemorrhagic shock. In hemorrhagic shock, microcirculatory flow and pressure are greatly reduced, creating an oxygen debt that may eventually become irreversible. During shock, tissues become hypoxic, cellular respiration turns to anaerobic metabolism, and the microcirculation rapidly begins to fail. This condition requires immediate fluid resuscitation to promote tissue reperfusion. The choice of fluid for resuscitation is whole blood; however, this may not be readily available and, on a larger scale, may be globally insufficient. Thus, extensive research on viable alternatives to blood has been undertaken in an effort to develop a clinically deployable blood substitute. This has not, as of yet, achieved fruition, in part due to an incomplete understanding of the complexities of the function of blood in the microcirculation. Hemodynamic resuscitation is acknowledged to be contingent on a number of factors other than volume expansion. The circulation of whole blood is carefully regulated to optimize oxygen delivery to the tissues via shear stress modulation through blood viscosity, inherent oxygen-carrying capacity, cell-free layer variation, and myogenic response, among other variables. Although plasma expanders can address a number of these issues, hemoglobin-based oxygen carriers (HBOCs) introduce a method of replenishing the intrinsic oxygen-carrying capacity of blood. There continue to be a number of issues related to HBOCs, but recent advances in the next-generation HBOCs show promise in the preservation of microcirculatory function and limiting toxicities. The development of HBOCs is now focused on viscosity and the degree of microvascular shear stress achieved in order to optimize vasoactive and oxygen delivery responses by leveraging the restoration and maintenance of physiological responses to blood flow in the microcirculation. Blood substitutes with higher viscous properties tend to improve oxygen delivery compared to those with lower viscosities. This review details current concepts in blood substitutes, particularly as they relate to trauma/hemorrhagic shock, with a specific focus on their complex interactions in the microcirculation.