"Blood failure" time to view blood as an organ: how oxygen debt contributes to blood failure and its implications for remote damage control resuscitation

Oxygenation and ventilation during prolonged experimental cardiopulmonary resuscitation with either continuous or 30:2 compression-to-ventilation ratios together with 10 cmH20 positive end-expiratory pressure

BACKGROUND

In refractory out-of-hospital cardiac arrest, the patient is commonly transported to hospital with mechanical continuous chest compressions (CCC). Limited data are available on the optimal ventilation strategy. Accordingly, we compared arterial oxygenation and haemodynamics during manual asynchronous continuous ventilation and compressions with a 30:2 compression-to-ventilation ratio together with the use of 10 cmH2O positive end-expiratory pressure (PEEP).

METHODS

Intubated and anaesthetized landrace pigs with electrically induced ventricular fibrillation were left untreated for 5 min (n = 31, weight ca. 55 kg), after which they were randomized to either the CCC group or the 30:2 group with the the LUCAS® 2 piston device and bag-valve ventilation with 100% oxygen targeting a tidal volume of 8 ml/kg with a PEEP of 10 cmH2O for 35 min. Arterial blood samples were analysed every 5 min, vital signs, near-infrared spectroscopy and electrical impedance tomography (EIT) were measured continuously, and post-mortem CT scans of the lungs were obtained.

RESULTS

The arterial blood values (median + interquartile range) at the 30-min time point were as follows: PaO2: 180 (86-302) mmHg for the 30:2 group; 70 (49-358) mmHg for the CCC group; PaCO2: 41 (29-53) mmHg for the 30:2 group; 44 (21-67) mmHg for the CCC group; and lactate: 12.8 (10.4-15.5) mmol/l for the 30:2 group; 14.7 (11.8-16.1) mmol/l for the CCC group. The differences were not statistically significant. In linear mixed models, there were no significant differences between the groups. The mean arterial pressures from the femoral artery, end-tidal CO2, distributions of ventilation from EIT and mean aeration of lung tissue in post-mortem CTs were similar between the groups. Eight pneumothoraces occurred in the CCC group and 2 in the 30:2 group, a statistically significant difference (p = 0.04).

CONCLUSIONS

The 30:2 and CCC protocols with a PEEP of 10 cmH2O resulted in similar gas exchange and vital sign outcomes in an experimental model of prolonged cardiac arrest with mechanical compressions, but the CCC protocol resulted in more post-mortem pneumothoraces.

Canadian tertiary care pediatric massive hemorrhage protocols: a survey and comprehensive national review

PURPOSE

Hemorrhage is the leading cause of pediatric death in trauma and cardiac arrest during surgery. Adult studies report improved patient outcomes using massive hemorrhage protocols (MHPs). Little is known about pediatric MHP adoption in Canada.

METHODS

After waived research ethics approval, we conducted a survey of Canadian pediatric tertiary care hospitals to study MHP activations. Transfusion medicine directors provided hospital/patient demographic and MHP activation data. The authors extracted pediatric-specific MHP data from requested policy/procedure documents according to seven predefined MHP domains based on the literature. We also surveyed educational and audit tools. The analysis only included MHPs with pediatric-specific content.

RESULTS

The survey included 18 sites (100% response rate). Only 13/18 hospitals had pediatric-specific MHP content: eight were dedicated pediatric hospitals, two were combined pediatric/obstetrical hospitals, and three were combined pediatric/adult hospitals. Trauma was the most common indication for MHP activation (54%), typically based on a specific blood volume anticipated/transfused over time (10/13 sites). Transport container content was variable. Plasma and platelets were usually not in the first container. There was little emphasis on balanced plasma/platelet to red-blood-cell ratios, and most sites (12/13) rapidly incorporated laboratory-guided goal-directed transfusion. Transfusion thresholds were consistent with recent guidelines. All protocols used tranexamic acid and eight sites used an audit tool.

DISCUSSION/CONCLUSION

Pediatric MHP content was highly variable. Activation demographics suggest underuse in nontrauma settings. Our findings highlight the need for a consensus definition for pediatric massive hemorrhage, a validated pediatric MHP activation tool, and prospective assessment of blood component ratios. A national pediatric MHP activation repository would allow for quality improvement metrics.

Blood transcriptomics mirror regulatory mechanisms during hibernation-a comparative analysis of the Djungarian hamster with other mammalian species

Hibernation enables many species of the mammalian kingdom to overcome periods of harsh environmental conditions. During this physically inactive state metabolic rate and body temperature are drastically downregulated, thereby reducing energy requirements (torpor) also over shorter time periods. Since blood cells reflect the organism´s current condition, it was suggested that transcriptomic alterations in blood cells mirror the torpor-associated physiological state. Transcriptomics on blood cells of torpid and non-torpid Djungarian hamsters and QIAGEN Ingenuity Pathway Analysis (IPA) revealed key target molecules (TMIPA), which were subjected to a comparative literature analysis on transcriptomic alterations during torpor/hibernation in other mammals. Gene expression similarities were identified in 148 TMIPA during torpor nadir among various organs and phylogenetically different mammalian species. Based on TMIPA, IPA network analyses corresponded with described inhibitions of basic cellular mechanisms and immune system-associated processes in torpid mammals. Moreover, protection against damage to the heart, kidney, and liver was deduced from this gene expression pattern in blood cells. This study shows that blood cell transcriptomics can reflect the general physiological state during torpor nadir. Furthermore, the understanding of molecular processes for torpor initiation and organ preservation may have beneficial implications for humans in extremely challenging environments, such as in medical intensive care units and in space.

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.

Implementation of a low-titre whole blood transfusion program in a civilian helicopter emergency medical service

BACKGROUND

Early balanced transfusion is associated with improved outcome in haemorrhagic shock patients. This study describes the implementation and evaluates the safety of a whole blood transfusion program in a civilian helicopter emergency medical service (HEMS).

METHODS

This prospective observational study was performed over a 5-year period at HEMS-Bergen, Norway. Patients in haemorrhagic shock receiving out of hospital transfusion of low-titre Group O whole blood (LTOWB) or other blood components were included. Two LTOWB units were produced weekly and rotated to the HEMS for forward storage. The primary endpoints were the number of patients transfused, mechanisms of injury/illness, adverse events and survival rates. Informed consent covered patient pathway from time of emergency interventions to last endpoint and subsequent data handling/storage.

RESULTS

The HEMS responded to 5124 patients. Seventy-two (1.4%) patients received transfusions. Twenty patients (28%) were excluded due to lack of consent (16) or not meeting the inclusion criteria (4). Of the 52 (100%) patients, 48 (92%) received LTOWB, nine (17%) received packed red blood cells (PRBC), and nine (17%) received freeze-dried plasma. Of the forty-six (88%) patients admitted alive to hospital, 35 (76%) received additional blood transfusions during the first 24 h. Categories were blunt trauma 30 (58%), penetrating trauma 7 (13%), and nontrauma 15 (29%). The majority (79%) were male, with a median age of 49 (IQR 27-70) years. No transfusion reactions, serious complications or logistical challenges were reported. Overall, 36 (69%) patients survived 24 h, and 28 (54%) survived 30 days.

CONCLUSIONS

Implementing a whole blood transfusion program in civilian HEMS is feasible and safe and the logistics around out of hospital whole blood transfusions are manageable. Trial registration The study is registered in the ClinicalTrials.gov registry (NCT02784951).

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.

The Norwegian blood preparedness project: A whole blood program including civilian walking blood banks for early treatment of patients with life-threatening bleeding in municipal health care services, ambulance services, and rural hospitals

Background

Civilian and military guidelines recommend early balanced transfusion to patients with life‐threatening bleeding to improve survival. To provide the best care to patients with hemorrhagic shock in regions with reduced access to evacuation, blood preparedness must be ensured also on a municipal health care level. The primary aim of the Norwegian Blood Preparedness project is to enable rural hospitals, prehospital ambulance services, and municipal health care services to start early balanced blood transfusions for patients with life‐threatening bleeding regardless of etiology.

Study Design and Methods

The project is designed based on three principles: (1) Early balanced transfusion should be provided for patients with life‐threatening bleeding, (2) Management of an emergency requires a planned and rehearsed day‐to‐day system for blood preparedness, and (3) A decentralized system is needed to ensure local self‐sufficiency in an emergency. We developed a system for education and training in blood‐based resuscitation with a focus on the municipal health care service.

Results

In this publication, we describe the implementation of emergency whole blood collections from a preplanned civilian walking blood bank in the municipal health care service. This includes donor selection, whole blood collection, emergency transfusion and quality assessment of practice.

Conclusion

We conclude that implementation of a Whole Blood based emergency transfusion program is feasible on all health care levels and that a preplanned civilian walking blood bank should be considered in locations were prolonged transport‐times may reduce access to blood transfusion for patients with life threatening bleeding.

Identifying critical DO2 with compensatory reserve during simulated hemorrhage in humans

BACKGROUND

Based on previous experiments in nonhuman primates, we hypothesized that DO₂ crit in humans is 5-6 ml O₂ ·kg^-1  min^-1 .

STUDY DESIGN AND METHODS

We measured the compensatory reserve (CRM) and calculated oxygen delivery (DO₂ ) in 166 healthy, normotensive, nonsmoking subjects (97 males, 69 females) during progressive central hypovolemia induced by lower body negative pressure as a model of ongoing hemorrhage. Subjects were classified as having either high tolerance (HT; N = 111) or low tolerance (LT; N = 55) to central hypovolemia.

RESULTS

HT and LT groups were matched for age, weight, BMI, and vital signs, DO₂ and CRM at baseline. The CRM-DO₂ relationship was best fitted to a logarithmic model in HT subjects (amalgamated R²  = 0.971) and a second-order polynomial model in the LT group (amalgamated R²  = 0.991). Average DO₂ crit for the entire subject cohort was estimated at 5.3 ml O₂ ·kg^-1  min^-1 , but was ~14% lower in HT compared with LT subjects. The reduction in DO₂ from 40% CRM to 20% CRM was 2-fold greater in the LT compared with the HT group.

CONCLUSIONS

Average DO₂ crit in humans is 5.3 ml O₂ ·kg^-1  min^-1 , but is ~14% lower in HT compared with LT subjects. The CRM-DO₂ relationship is curvilinear in humans, and different when comparing HT and LT individuals. The threshold for an emergent monitoring signal should be recalibrated from 30% to 40% CRM given that the decline in DO₂ from 40% CRM to 20% CRM for LT subjects is located on the steepest part of the CRM-DO₂ relationship.

Time to Hemostasis After Trauma and Transfusion by Patient Blood Type

BACKGROUND

Although evidence supports an increased risk of mortality after major trauma among patients with type O blood, the relationship between patient blood type and clinical outcomes aside from mortality has not been fully elucidated.

OBJECTIVE

To examine the relationship between patient blood type and time to hemostasis after trauma and massive transfusion.

METHODS

A secondary analysis of the Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) trial was performed (N = 544). Blood type was dichotomized into type O versus non-type O. It was hypothesized that patients with non-type O blood would achieve hemostasis more quickly owing to the theoretical presence of increased clotting factors. Bivariate analysis and multiple Cox regression were conducted to test this assumption.

RESULTS

No significant difference was found in time to hemostasis between patients with type O blood and those with non-type O blood. However, mechanism of injury, diastolic blood pressure, and international normalized ratio affected the time to hemostasis in these trauma patients.

CONCLUSION

This study showed no significant difference in time to hemostasis by blood type.

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.

Injuries associated with hypotension after trauma: Is it always haemorrhage?

Introduction

Restricted fluid replacement strategy is one part of damage control resuscitation for patients with trauma haemorrhage. However, not all patients presenting with physiological symptoms suggestive of haemorrhage are bleeding. This descriptive study aims to compare demographics and injuries in adult and older trauma patients presenting to the Emergency Department with hypotension versus normotension.

Methods

This was a retrospective, descriptive data analysis from a UK trauma registry. The records from one major trauma centre were analysed between 2014–2019, and every hypotensive (systolic blood pressure <90 mmHg) trauma patient investigated for injuries associated with hypotension. The hypotensive threshold for older patients was also adjusted to 110 mmHg for sub-cohort analysis.

Results

6245 trauma patients were included, of which 255 (4.1%) arrived hypotensive at the Emergency Department. Significant blood loss was identified in 32.2% of those cases. In 27.1%, multiple potential associations obscured the underlying mechanism for the hypotension but were more commonly associated with hypotension than with normotension. Over a third (37.5%) were ≥65 years old. Neurological injuries occurred more frequently in both older hypotensive groups than younger patients.

Conclusions

This study sought to compare injuries of adult and older trauma patients to aid trauma teams with decision making. In severely injured hypotensive patients, significant blood loss was the principal association with hypotension. However, several factors can mimic bleeding in the hypotensive trauma patient, which should be carefully considered. A prospective study is needed to clarify the characteristics and causes of bleeding mimics.

Recovery of organ-specific tissue oxygen delivery at restrictive transfusion thresholds after fluid treatment in ovine haemorrhagic shock

Background

Fluid resuscitation is the standard treatment to restore circulating blood volume and pressure after massive haemorrhage and shock. Packed red blood cells (PRBC) are transfused to restore haemoglobin levels. Restoration of microcirculatory flow and tissue oxygen delivery is critical for organ and patient survival, but these parameters are infrequently measured. Patient Blood Management is a multidisciplinary approach to manage and conserve a patient’s own blood, directing treatment options based on broad clinical assessment beyond haemoglobin alone, for which tissue perfusion and oxygenation could be useful. Our aim was to assess utility of non-invasive tissue-specific measures to compare PRBC transfusion with novel crystalloid treatments for haemorrhagic shock.

Methods

A model of severe haemorrhagic shock was developed in an intensive care setting, with controlled haemorrhage in sheep according to pressure (mean arterial pressure 30–40 mmHg) and oxygen debt (lactate > 4 mM) targets. We compared PRBC transfusion to fluid resuscitation with either PlasmaLyte or a novel crystalloid. Efficacy was assessed according to recovery of haemodynamic parameters and non-invasive measures of sublingual microcirculatory flow, regional tissue oxygen saturation, repayment of oxygen debt (arterial lactate), and a panel of inflammatory and organ function markers. Invasive measurements of tissue perfusion, oxygen tension and lactate levels were performed in brain, kidney, liver, and skeletal muscle. Outcomes were assessed during 4 h treatment and post-mortem, and analysed by one- and two-way ANOVA.

Results

Each treatment restored haemodynamic and tissue oxygen delivery parameters equivalently (p > 0.05), despite haemodilution after crystalloid infusion to haemoglobin concentrations below 70 g/L (p < 0.001). Recovery of vital organ-specific perfusion and oxygen tension commenced shortly before non-invasive measures improved. Lactate declined in all tissues and correlated with arterial lactate levels (p < 0.0001). The novel crystalloid supported rapid peripheral vasodilation (p = 0.014) and tended to achieve tissue oxygen delivery targets earlier. PRBC supported earlier renal oxygen delivery (p = 0.012) but delayed peripheral perfusion (p = 0.034).

Conclusions

Crystalloids supported vital organ oxygen delivery after massive haemorrhage, despite haemodilution to < 70 g/L, confirming that restrictive transfusion thresholds are appropriate to support oxygen delivery. Non-invasive tissue perfusion and oximetry technologies merit further clinical appraisal to guide treatment for massive haemorrhage in the context of Patient Blood Management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-022-00439-6.

Risk and prognostic factors of replantation failure in patients with severe traumatic major limb mutilation

Purpose

Traumatic mutilation of major limbs can result in limb loss, motor disability, or death. Patients who had replantation failure needed to undergo additional surgeries (even amputation) and had a longer length of hospital stay. Here, we determined the risk and prognostic factors of replantation failure in patients with traumatic major limb mutilation.

Methods

This retrospective study included adult inpatients with severed traumatic major limb mutilation who underwent replantation from Suzhou Ruixing Medical Group from October 18, 2016 to July 31, 2020. Demographic, and clinical characteristics including traumatic conditions, laboratory findings, mangled extremity severity scores (MESS), treatments, and outcomes of the patients were collected. Data were used to analyze predictors and risk factors for replantation failure.

Results

Among the 66 patients, 48 (72.7%) were males, the median age was 47.0 years old. Replantation failure occurred in 48 patients (72.7%). The area under the curve of the joint prediction of lactic acid on admission, 72-h cumulative fluid balance, and albumin level immediately postoperatively was 0.838 (95% confidence interval [CI], 0.722–0.954; P < 0.001) with a sensitivity of 89.7% and a specificity of 69.2%. Lower limb trauma (odds ratio [OR] 8.65, 95% CI 1.64–45.56, P = 0.011), mangled extremity severity scores (OR 2.24, 95% CI 1.25–4.01, P = 0.007), and first 72-h cumulative fluid balance > 4885.6 mL (OR 10.25, 95% CI 1.37–76.93, P = 0.024) were independent risk factors for replantation failure.

Conclusions

Lower limb trauma, mangled extremity severity scores, and cumulative water balance were associated with replantation failure, implying that fluid management is necessary for major limb salvage. More studies are needed to explore the predictive power of indicators related to tissue oxygenation and wound healing for replantation failure.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00068-021-01876-w.

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.

An Ovine Model of Hemorrhagic Shock and Resuscitation, to Assess Recovery of Tissue Oxygen Delivery and Oxygen Debt, and Inform Patient Blood Management

BACKGROUND

Aggressive fluid or blood component transfusion for severe hemorrhagic shock may restore macrocirculatory parameters, but not always improve microcirculatory perfusion and tissue oxygen delivery. We established an ovine model of hemorrhagic shock to systematically assess tissue oxygen delivery and repayment of oxygen debt; appropriate outcomes to guide Patient Blood Management.

METHODS

Female Dorset-cross sheep were anesthetized, intubated, and subjected to comprehensive macrohemodynamic, regional tissue oxygen saturation (StO2), sublingual capillary imaging, and arterial lactate monitoring confirmed by invasive organ-specific microvascular perfusion, oxygen pressure, and lactate/pyruvate levels in brain, kidney, liver, and skeletal muscle. Shock was induced by stepwise withdrawal of venous blood until MAP was 30 mm Hg, mixed venous oxygen saturation (SvO2) < 60%, and arterial lactate >4 mM. Resuscitation with PlasmaLyte® was dosed to achieve MAP > 65 mm Hg.

RESULTS

Hemorrhage impacted primary outcomes between baseline and development of shock: MAP 89 ± 5 to 31 ± 5 mm Hg (P < 0.01), SvO2 70 ± 7 to 23 ± 8% (P < 0.05), cerebral regional tissue StO2 77 ± 11 to 65 ± 9% (P < 0.01), peripheral muscle StO2 66 ± 8 to 16 ± 9% (P < 0.01), arterial lactate 1.5 ± 1.0 to 5.1 ± 0.8 mM (P < 0.01), and base excess 1.1 ± 2.2 to -3.6 ± 1.7 mM (P < 0.05). Invasive organ-specific monitoring confirmed reduced tissue oxygen delivery; oxygen tension decreased and lactate increased in all tissues, but moderately in brain. Blood volume replacement with PlasmaLyte® improved primary outcome measures toward baseline, confirmed by organ-specific measures, despite hemoglobin reduced from baseline 10.8 ± 1.2 to 5.9 ± 1.1 g/dL post-resuscitation (P < 0.01).

CONCLUSION

Non-invasive measures of tissue oxygen delivery and oxygen debt repayment are suitable outcomes to inform Patient Blood Management of hemorrhagic shock, translatable for pre-clinical assessment of novel resuscitation strategies.

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.

A whole blood based resuscitation strategy in civilian medical services: Experience from a Norwegian hospital in the period 2017-2020

BACKGROUND

Civilian and military guidelines recommend early balanced transfusion to patients with life-threatening bleeding. Low titer group O whole blood was introduced as the primary blood product for resuscitation of massive hemorrhage at Haukeland University Hospital, Bergen, Norway, in December 2017. In this report, we describe the whole blood program and present results from the first years of routine use.

STUDY DESIGN AND METHODS

Patients who received whole blood from December 2017 to April 2020 were included in our quality registry for massive transfusions. Post-transfusion blood samples were collected to analyze isohemagglutinin (anti-A/-B) and hemolysis markers. Administration of other blood products, transfusion reactions, and patient survival (days 1 and 30) were recorded. User experiences were surveyed for both clinical and laboratory staff.

RESULTS

Two hundred and five patients (64% male and 36% female) received 836 units in 226 transfusion episodes. Patients received a mean of 3.7 units (range 1-35) in each transfusion episode. The main indications for transfusion were trauma (26%), gastrointestinal (22%), cardiothoracic/vascular (18%), surgical (18%), obstetric (11%), and medical (5%) bleeding. There was no difference in survival between patients with blood type O when compared with non-group O. Haptoglobin level was lower in the transfusion episodes for non-O group patients, however no clinical hemolysis was reported. No patients had conclusive transfusion-associated adverse events. Both clinical and laboratory staff preferred whole blood to component therapy for massive transfusion.

DISCUSSION

The experience from Haukeland University Hospital indicates that whole blood is feasible, safe, and effective for in-hospital treatment of bleeding.

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.

Using Rotational Thromboelastometry to Identify Early Allograft Dysfunction after Living Donor Liver Transplantation

Background: Diagnostic tests for early allograft dysfunction (EAD) after living donor liver transplantation (LDLT) vary widely. We aimed to evaluate the predictive value of rotational thromboelastometry (ROTEM)-derived parameters in EAD. Materials and Methods: A total of 121 patients were reviewed. The definition of EAD proposed by Olthoff et al. included the presence of any of the following at postoperative day 7: bilirubin level ≥ 10 mg/dL, INR ≥ 1.6, or serum AST or ALT levels > 2000 IU/L. All patients underwent ROTEM assay, which consisted of an extrinsically activated thromboelastometric test (EXTEM) before and 24 h after LDLT. Results: The 1-year/2-year OS were 68.%8/64.5% and 94.4%/90.8% for the EAD and non-EAD groups, respectively (p = 0.001). Two independent risks were identified for EAD, the postoperative clotting time (CT, p = 0.026) and time to maximum clot firmness (maximum clot firmness (MCF)-t, p = 0.009) on the EXTEM. CT yielded a specificity of 82.0% and negative predictive value of 83.0%, and MCF-t displayed a specificity of 76.4% and negative predictive value of 81.9% in diagnosing EAD. The use of the 24 h post-LDLT ROTEM increased the effectiveness of predicting overall survival (OS) compared to using the Olthoff’s EAD criteria alone (p < 0.001). Conclusion: We conclude that CT and MCF on EXTEM were independent predictors of EAD. The 24 h post-LDLT ROTEM can be used with conventional laboratory tests to diagnose EAD. It increases the effectiveness of predicting OS.

Vasopressors in Trauma: A Never Event?

Vasopressor use in severely injured trauma patients is discouraged due to concerns that vasoconstriction will worsen organ perfusion and result in increased mortality and organ failure in hypotensive trauma patients. Hypotensive resuscitation is advocated based on limited data that lower systolic blood pressure and mean arterial pressure will result in improved mortality. It is classically taught that hypotension and hypovolemia in trauma are associated with peripheral vasoconstriction. However, the pathophysiology of traumatic shock is complex and involves multiple neurohormonal interactions that are ultimately manifested by an initial sympathoexcitatory phase that attempts to compensate for acute blood loss and is characterized by vasoconstriction, tachycardia, and preserved mean arterial blood pressure. The subsequent hypotension observed in hemorrhagic shock reflects a sympathoinhibitory vasodilation phase. The objectives of hemodynamic resuscitation in hypotensive trauma patients are restoring adequate intravascular volume with a balanced ratio of blood products, correcting pathologic coagulopathy, and maintaining organ perfusion. Persistent hypotension and hypoperfusion are associated with worse coagulopathy and organ function. The practice of hypotensive resuscitation would appear counterintuitive to the goals of traumatic shock resuscitation and is not supported by consistent clinical data. In addition, excessive volume resuscitation is associated with adverse clinical outcomes. Therefore, in the resuscitation of traumatic shock, it is necessary to target an appropriate balance with intravascular volume and vascular tone. It would appear logical that vasopressors may be useful in traumatic shock resuscitation to counteract vasodilation in hemorrhage as well as other clinical conditions such as traumatic brain injury, spinal cord injury, multiple organ dysfunction syndrome, and vasodilation of general anesthetics. The purpose of this article is to discuss the controversy of vasopressors in hypotensive trauma patients and advocate for a nuanced approach to vasopressor administration in the resuscitation of traumatic shock.

Damage control in the emergency department, a bridge to life

Patients with hemodynamic instability have a sustained systolic blood pressure less or equal to 90 mmHg, a heart rate greater or equal to 120 beats per minute and an acute compromise of the ventilation/oxygenation ratio and/or an altered state of consciousness upon admission. These patients have higher mortality rates due to massive hemorrhage, airway injury and/or impaired ventilation. Damage control resuscitation is a systematic approach that aims to limit physiologic deterioration through strategies that address the physiologic debt of trauma. This article aims to describe the experience earned by the Trauma and Emergency Surgery Group (CTE) of Cali, Colombia in the management of the severely injured trauma patient in the emergency department following the basic principles of damage control surgery. Since bleeding is the main cause of death, the management of the severely injured trauma patient in the emergency department requires a multidisciplinary team that performs damage control maneuvers aimed at rapidly controlling bleeding, hemostatic resuscitation, and/or prompt transfer to the operating room, if required.

Pathogen reduction of whole blood: Supplementing fibrinogen partly corrects clot formation in a massive transfusion model

BACKGROUND

The use of whole blood (WB) to treat trauma patients is becoming more common. Similar to the treatment of individual components, pathogen inactivation (PI) technologies are available to treat WB. The impact of PI on WB function is not well understood. This study investigated the impact of PI of WB with riboflavin/ultraviolet (UV) light on its hemostatic function by modeling transfusion scenarios for trauma patients and assessing transfusion efficacy by rotational thromboelastometry (ROTEM). As fibrinogen is affected by PI of WB, the effect of fibrinogen supplementation commonly used in trauma patients was also analyzed in this model.

STUDY DESIGN AND METHODS

Trauma transfusion scenarios were simulated by mixing untreated WB or WB treated with the Mirasol PI technology (riboflavin/UV) in different ratios with hemodiluted blood, and the thromboelasticity was monitored by ROTEM. The impact of supplementation with the fibrinogen concentrate RiaSTAP was investigated in this model.

RESULTS

Pathogen-inactivated WB (PI-WB) showed decreased activity in the hemostatic profile compared to the untreated control. Hemodiluted blood at a hematocrit (hct) of 20%, which was reconstituted with PI-WB or untreated WB, exhibited increased alpha values, maximum clot firmness, and clot formation time. Simulating transfusion scenarios by blood replacement with PI-WB resulted in a significant difference in ROTEM parameters between reconstituted PI-treated and -untreated WB (p ≥ .05). The effect of PI treatment waned when PI-WB was enriched with fibrinogen.

CONCLUSION

ROTEM investigations suggest that PI treatment has a negative impact on WB clot formation unless fibrinogen supplementation is used.

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.

A Randomized Trial of Mentored vs Nonmentored Military Medics Compared in the Application of a Wound Clamp Without Prior Training: When to Shut Up and Just Watch!

INTRODUCTION

Hemorrhage control is a basic task required of first responders and typically requires technical interventions during stressful circumstances. Remote telementoring (RTM) utilizes information technology to guide inexperienced providers, but when this is useful remains undefined.

METHODS

Military medics were randomized to mentoring or not from an experienced subject matter expert during the application of a wound clamp (WC) to a simulated bleed. Inexperienced, nonmentored medics were given a 30-second safety briefing; mentored medics were not. Objective outcomes were time to task completion and success in arresting simulated bleeding.

RESULTS

Thirty-three medics participated (16 mentored and 17 nonmentored). All (100%) successfully applies the WC to arrest the simulated hemorrhage. RTM significantly slowed hemorrhage control (P = 0.000) between the mentored (40.4 ± 12.0 seconds) and nonmentored (15.2 ± 10.3 seconds) groups. On posttask questionnaire, all medics subjectively rated the difficulty of the wound clamping as 1.7/10 (10 being extremely hard). Discussion: WC application appeared to be an easily acquired technique that was effective in controlling simulated extremity exsanguination, such that RTM while feasible did not improve outcomes. Limitations were the lack of true stress and using simulation for the task. Future research should focus on determining when RTM is useful and when it is not required.

Effects of Early Altitude Exposure on the Open Abdomen After Laparotomy in Trauma

INTRODUCTION

While damage control surgery and resuscitation techniques have revolutionized the care of injured service members who sustain severe traumatic hemorrhage, the physiologic and inflammatory consequences of hemostatic resuscitation and staged abdominal surgery in the face of early aeromedical evacuation (AE) have not been investigated. We hypothesized that post-injury AE with an open abdomen would have significant physiologic and inflammatory consequences compared to AE with a closed abdomen.

MATERIALS AND METHODS

Evaluation of resuscitation and staged abdominal closure was performed using a murine model of hemorrhagic shock with laparotomy. Mice underwent controlled hemorrhage to a systolic blood pressure of 25 mmHg and received either no resuscitation, blood product resuscitation, or Hextend resuscitation to a systolic blood pressure of either 50 mmHg (partial resuscitation) or 80 mmHg (complete resuscitation). Laparotomies were either closed prior to AE (closed abdomens) or left open during AE (open abdomens) and subsequently closed. AE was simulated with a 1-hour exposure to a hypobaric hypoxic environment at 8,000 feet altitude. Mice were euthanized at 0, 4, or 24 hours following AE. Serum was collected and analyzed for physiologic variables and inflammatory cytokine levels. Samples of lung and small intestine were collected for tissue cytokine and myeloperoxidase analysis as indicators of intestinal inflammation. Survival curves were also performed.

RESULTS

Unresuscitated mice sustained an 85% mortality rate from hemorrhage and laparotomy, limiting the assessment of the effect of simulated AE in these subgroups. Overall survival was similar among all resuscitated groups regardless of the presence of hypobaric hypoxia, type of resuscitation, or abdominal closure status. Simulated AE had no observed effects on acid/base imbalance or the inflammatory response as compared to ground level controls. All mice experienced both metabolic acidosis and an acute inflammatory response after hemorrhage and injury, represented by an initial increase in serum interleukin (IL)-6 levels. Furthermore, mice with open abdomens had an elevated inflammatory response with increased levels of serum IL-10, serum tumor necrosis factor alpha, intestinal IL-6, intestinal IL-10, and pulmonary myeloperoxidase.

CONCLUSION

These results demonstrate the complex interaction of AE and temporary or definitive abdominal closure after post-injury laparotomy. Contrary to our hypothesis, we found that AE in those animals with open abdomens is relatively safe with no difference in mortality compared to those with closed abdomens. However, given the physiologic and inflammatory changes observed in animals with open abdomens, further evaluation is necessary prior to definitive recommendations regarding the safety or downstream effects of exposure to AE prior to definitive abdominal closure.

Effects of Sanguinate on Systemic and Microcirculatory Variables in a Model of Prolonged Hemorrhagic Shock

Supplemental Digital Content is available in the text

Background:

Hemorrhage and its complications are the leading cause of preventable death from trauma in young adults, especially in remote locations. To address this, deliverable, shelf-stable resuscitants that provide therapeutic benefits throughout the time course of hemorrhagic shock and the progressive ischemic injury it produces are needed. SANGUINATE^∗ is a novel bovine PEGylated carboxyhemoglobin-based oxygen carrier, which has desirable oxygen-carrying and oncotic properties as well as a CO moiety to maintain microvascular perfusion.

Objectives:

To compare the crystalloid (Lactated Ringer's Solution; LRS), and the colloid (Hextend^†) standards of care with SANGUINATE in a post “golden hour” resuscitation model.

Methods:

Rats underwent a controlled, stepwise blood withdrawal (45% by volume), were maintained in untreated hemorrhagic shock state for >60 min, resuscitated with a 20% bolus of one of the three test solutions, and observed till demise. Parameters of tissue oxygenation (P_ISFO₂), arteriolar diameters, and mean arterial pressure (MAP) were collected.

Results:

SANGUINATE-treated animals survived significantly longer than those treated with Hextend and LRS. SANGUINATE also significantly increased tissue P_ISFO₂ 2 h after resuscitation, whereas LRS and Hextend did not. SANGUINATE also produced a significantly higher MAP, which was hypotensive compared to baseline, that endured until demise.

Conclusions:

Resuscitation with SANGUINATE after prolonged hemorrhagic shock improves survival, MAP, and P_ISFO₂ compared with standard of care plasma expanders. Since the pathologies of hemorrhagic shock and the associated systemic ischemia are progressive, preclinical studies of this nature are essential to determine efficacy of new resuscitants across the range of possible times to treatment.

Cold-stored whole blood in a Norwegian emergency helicopter service: an observational study on storage conditions and product quality

BACKGROUND

Increasing numbers of emergency medical service agencies and hospitals are developing the capability to administer blood products to patients with hemorrhagic shock. Cold-stored whole blood (WB) is the only single product available to prehospital providers who aim to deliver a balanced resuscitation strategy. However, there are no data on the safety and in vitro characteristics of prehospital stored WB. This study aimed to describe the effects on in vitro quality of storing WB at remote helicopter bases in thermal insulating containers.

STUDY DESIGN AND METHODS

We conducted a two-armed single-center study. Twenty units (test) were stored in airtight thermal insulating containers, and 20 units (controls) were stored according to routine procedures in the Haukeland University Hospital Blood Bank. Storage conditions were continuously monitored during emergency medical services missions and throughout remote and blood bank storage. Hematologic and metabolic variables, viscoelastic properties, and platelet (PLT) aggregation were measured on Days 1, 8, 14, and 21.

RESULTS

Storage conditions complied with the EU guidelines throughout remote and in-hospital storage for 21 days. There were no significant differences in PLT aggregation, viscoelastic properties, and hematology variables between the two groups. Minor significantly lower pH, glucose, and base excess and higher lactate were observed after storage in airtight containers.

CONCLUSION

Forward cold storage of WB is safe and complies with EU standards. No difference is observed in hemostatic properties. Minor differences in metabolic variables may be related to the anaerobic conditions within the thermal box.

Recent advances in use of fresh frozen plasma, cryoprecipitate, immunoglobulins, and clotting factors for transfusion support in patients with hematologic disease

Hematologic diseases include a broad range of acquired and congenital disorders, many of which affect plasma proteins that control hemostasis and immune responses. Therapeutic interventions for these disorders include transfusion of plasma, cryoprecipitate, immunoglobulins, or convalescent plasma-containing therapeutic antibodies from patients recovering from infectious diseases, as well as concentrated pro- or anticoagulant factors. This review will focus on recent advances in the uses of plasma and its derivatives for patients with acquired and congenital hematologic disorders.

The History of Fluid Resuscitation for Bleeding

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

Epidemiological and Accounting Analysis of Ground Ambulance Whole Blood Transfusion

INTRODUCTION

In October 2017, the American Association of Blood Bankers (AABB; Bethesda, Maryland USA) approved a petition to allow low-titer group O whole blood as a standard product without the need for a waiver. Around that time, a few Texas, USA-based Emergency Medical Services (EMS) systems incorporated whole blood into their ground ambulances. The purpose of this project was to describe the epidemiology of ground ambulance patients that received a prehospital whole blood transfusion. The secondary aim of this project was to report an accounting analysis of these ground ambulance prehospital whole blood programs.

METHODS

The dataset came from the Harris County Emergency Service District 48 Fire Department (HCESD 48; Harris County, Texas USA) and San Antonio Fire Department (SAFD; San Antonio, Texas USA) whole blood Quality Assurance/Quality Improvement (QA/QI) databases from September 2017 through December 2018. The primary outcome of this study was the prehospital transfusion indication. The secondary outcome was the projected cost per life saved during the first 10 years of the prehospital whole blood initiative.

RESULTS

Of 58 consecutive prehospital whole blood administrations, the team included all 58 cases. Hemorrhagic shock from a non-traumatic etiology accounted for 46.5% (95% CI, 34.3%-59.2%) of prehospital whole blood recipients. In the non-traumatic hemorrhagic shock cohort, gastrointestinal hemorrhage was the underlying etiology of hemorrhagic shock in 66.7% (95% CI, 47.8%-81.4%) of prehospital whole blood transfusion recipients. The projected average cost to save a life in Year 10 was US$5,136.51 for the combined cohort, US$4,512.69 for HCESD 48, and US$5,243.72 for SAFD EMS.

CONCLUSION

This retrospective analysis of ground ambulance patients that receive prehospital whole blood transfusion found that non-traumatic etiology accounted for 46.5% (95% CI, 34.3%-59.2%) of prehospital whole blood recipients. Additionally, the accounting analysis suggests that by Year 10 of a ground ambulance whole blood transfusion program, the average cost to save a life will be approximately US$5,136.51.

Human Red Blood Cells as Oxygen Carriers to Improve Ex-Situ Liver Perfusion in a Rat Model

Ex-situ machine perfusion (MP) has been increasingly used to enhance liver quality in different settings. Small animal models can help to implement this procedure. As most normothermic MP (NMP) models employ sub-physiological levels of oxygen delivery (DO₂), the aim of this study was to investigate the effectiveness and safety of different DO₂, using human red blood cells (RBCs) as oxygen carriers on metabolic recovery in a rat model of NMP. Four experimental groups (n = 5 each) consisted of (1) native (untreated/control), (2) liver static cold storage (SCS) 30 min without NMP, (3) SCS followed by 120 min of NMP with Dulbecco-Modified-Eagle-Medium as perfusate (DMEM), and (4) similar to group 3, but perfusion fluid was added with human RBCs (hematocrit 15%) (BLOOD). Compared to DMEM, the BLOOD group showed increased liver DO₂ (p = 0.008) and oxygen consumption ( V O ˙ ₂) (p < 0.001); lactate clearance (p < 0.001), potassium (p < 0.001), and glucose (p = 0.029) uptake were enhanced. ATP levels were likewise higher in BLOOD relative to DMEM (p = 0.031). V O ˙ ₂ and DO₂ were highly correlated (p < 0.001). Consistently, the main metabolic parameters were directly correlated with DO₂ and V O ˙ ₂. No human RBC related damage was detected. In conclusion, an optimized DO₂ significantly reduces hypoxic damage-related effects occurring during NMP. Human RBCs can be safely used as oxygen carriers.

Damage Control Resuscitation

Damage control resuscitation (DCR) is a strategy for resuscitating patients from hemorrhagic shock to rapidly restore homeostasis. Efforts are focused on blood product transfusion with whole blood or component therapy closely approximating whole blood, limited use of crystalloid to avoid dilutional coagulopathy, hypotensive resuscitation until bleeding control is achieved, empiric use of tranexamic acid, prevention of acidosis and hypothermia, and rapid definitive surgical control of bleeding. Patients receiving uncrossmatched Type O blood in the emergency department and later receiving cumulative transfusions of 10 or more red blood cell units in the initial 24-hour post-injury (massive transfusion) are widely recognized as being at increased risk of morbidity and mortality due to exsanguination. Ideally, these patients should be rapidly identified, however anticipating transfusion needs is challenging. Useful indicators of massive transfusion reviewed in this guideline include: systolic blood pressure <110 mmHg, heart rate > 105 bpm, hematocrit <32%, pH < 7.25, injury pattern (above-the-knee traumatic amputation especially if pelvic injury is present, multi-amputation, clinically obvious penetrating injury to chest or abdomen), >2 regions positive on Focused Assessment with Sonography for Trauma (FAST) scan, lactate concentration on admission >2.5, admission international normalized ratio ≥1.2-1.4, near infrared spectroscopy-derived StO2 < 75% (in practice, rarely available), BD > 6 meq/L. Unique aspects of out-of-hospital DCR (point of injury, en-route, and remote DCR) and in-hospital (Medical Treatment Facilities: Role 2b/Forward surgical teams - role 3/ combat support hospitals) are reviewed in this guideline, along with pediatric considerations.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prehospital Blood Product Transfusion in Mountain Rescue Operations

Severely injured patients with hemorrhage present major challenges for emergency medical services, especially during mountain rescue missions in which harsh environmental conditions and long out-of-hospital times are frequent. Because uncontrolled hemorrhage is the leading cause of death within the first 48 hours after severe trauma, initiating damage control resuscitation (DCR) as early as possible after severe trauma and exporting the concept of DCR to the out-of-hospital arena is pivotal for patient survival. Appropriate bleeding control, management of coagulopathy, and transfusion of blood products are core aspects of DCR. This review summarizes the available evidence on out-of-hospital blood product transfusion and the management of coagulopathy with a special focus on mountain rescue missions. An overview of upcoming trials and possible future trends in the management of coagulopathy during rescue operations is provided.

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

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

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

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

Hemorrhagic Shock and the Microvasculature

The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.

Efficacy of Uncross-Matched Type O Packed Red Blood Cell Transfusion to Traumatic Shock Patients: a Propensity Score Match Study

A new blood bank system was established in our trauma bay, which allowed immediate utilization of uncross-matched type O packed red blood cells (UORBCs). We investigated the efficacy of UORBC compared to that of the ABO type-specific packed red blood cells (ABO RBCs) from before the bank was installed. From March 2016 to February 2017, data from trauma patients who received UORBCs in the trauma bay were compared with those of trauma patients who received ABO RBCs from January 2013 to December 2015. Propensity matching was used to overcome retrospective bias. The primary outcome was 24-hour mortality, while the secondary outcomes were in-hospital mortality and intensive care unit (ICU) length of stay (LOS). Data from 252 patients were reviewed and UORBCs were administered to 64 patients. The time to transfusion from emergency room admission was shorter in the UORBC group (11 [7-16] minutes vs. 44 [29-72] minutes, P < 0.001). After propensity matching, 47 patients were included in each group. The 24-hour mortality (4 [8.5%] vs. 9 [13.8%], P = 0.135), in-hospital mortality (14 [29.8%] vs. 18 [38.3%], P = 0.384), and ICU LOS (9 [4-19] days vs. 5 [0-19] days, P = 0.155) did not differ significantly between groups. The utilization of UORBCs resulted in a faster transfusion but did not significantly improve the clinical outcomes in traumatic shock patients in this study. However, the tendency for lower mortality in the UORBC group suggested the need for a large study.

Leukocyte filtration lesion impairs functional coagulation in banked whole blood

BACKGROUND

Whole blood (WB) transfusion is a promising alternative to component therapy in hemostatic resuscitation. Use of banked WB requires filtration of white blood cells (leukoreduction) and an established shelf life during which WB retains coagulant capacities. The goal of this study was to define the time course of coagulation stability in leukoreduced compared to unfiltered WB under standard refrigeration conditions.

METHODS

Twelve WB units were donated by healthy volunteers after routine screening. Five units underwent standard leukocyte filtration and five did not. Two units were aliquoted into filtered and unfiltered samples, with platelets added to each sample on day 14. Units were stored at 4°C and sampled on days 0, 1, 2, 3, 4, 5, 6, 7, 10, 14, 21, 28, and 35 for immediate thromboelastography (TEG) analysis, and centrifuged and stored at -80°C for later calibrated automated thrombogram and coagulation factor assays.

RESULTS

K-dependent factors and fibrinogen were low normal, decreased slightly over 35 days and were similar between unfiltered and filtered units. Labile factors were better preserved in filtered units, although unfiltered units did not show impaired coagulation over 35 days. Filtered blood had delayed clot initiation on days 0, 1, and 2 as measured by TEG R (p < 0.021); slower clot progression (TEG α-angle) on days 0, 1, 2, 3, 4, 5, and 6 (p < 0.023); weaker final clot (TEG MA) on all days (p < 0.0001). Thrombin generation was delayed on day 28 (p = 0.046) and decreased on days 10, 21, 28, and 35 (p < 0.034). Addition of platelets to filtered WB rescued TEG MA.

CONCLUSION

Filtered WB had decreased functional clotting capacity and thrombin generation and may not be suitable for hemostatic resuscitation as the sole blood product.

LEVEL OF EVIDENCE

Therapeutic, level IV.

The Damage Control Surgery in Austere Environments Research Group (DCSAERG): A dynamic program to facilitate real-time telementoring/telediagnosis to address exsanguination in extreme and austere environments

Hemorrhage is the most preventable cause of posttraumatic death. Many cases are potentially anatomically salvageable, yet remain lethal without logistics or trained personnel to deliver diagnosis or resuscitative surgery in austere environments. Revolutions in technology for remote mentoring of ultrasound and surgery may enhance capabilities to utilize the skill sets of non-physicians. Thus, our research collaborative explored remote mentoring to empower non-physicians to address junctional and torso hemorrhage control in austere environments. Major studies involved using remote-telementored ultrasound (RTMUS) to identify torso and junctional exsanguination, remotely mentoring resuscitative surgery for torso hemorrhage control, understanding and mitigating physiological stress during such tasks, and the technical practicalities of conducting damage control surgery (DCS) in austere environments. Iterative projects involved randomized guiding of firefighters to identify torso (RCT) and junctional (pilot) hemorrhage using RTMUS, randomized remote mentoring of MedTechs conducting resuscitative surgery for torso exsanguination in an anatomically realistic surgical trainer ("Cut Suit") including physiological monitoring, and trained surgeons conducting a comparative randomized study for torso hemorrhage control in normal (1g) versus weightlessness (0g). This work demonstrated that firefighters could be remotely mentored to perform just-in-time torso RTMUS on a simulator. Both firefighters and mentors were confident in their abilities, the ultrasounds being 97% accurate. An ultrasound-naive firefighter in Memphis could also be remotely mentored from Hawaii to identify and subsequently tamponade an arterial junctional hemorrhage using RTMUS in a live tissue model. Thereafter, both mentored and unmentored MedTechs and trained surgeons completed resuscitative surgery for hemorrhage control on the Cut-Suit, demonstrating practicality for all involved. While remote mentoring did not decrease blood loss among MedTechs, it increased procedural confidence and decreased physiologic stress. Therefore, remote mentoring may increase the feasibility of non-physicians conducting a psychologically daunting task. Finally, DCS in weightlessness was feasible without fundamental differences from 1g. Overall, the collective evidence suggests that remote mentoring supports diagnosis, noninvasive therapy, and ultimately resuscitative surgery to potentially rescue those exsanguinating in austere environments and should be more rigorously studied.