Impact of high ratios of plasma-to-red cell concentrate on the incidence of acute respiratory distress syndrome in UK transfused combat casualties

Combat Trauma-Related Acute Respiratory Distress Syndrome: A Scoping Review

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are known complications of injuries in combat casualties, but there has been no review characterizing them. This scoping review aims to map the combat trauma-related ALI/ARDS literature and characterize these conditions in the military population.

DATA SOURCES

Pubmed was searched from 1969 to April 2022.

STUDY SELECTION

Studies were included if they examined ALI/ARDS or related entities (blast lung injury [BLI], transfusion-related acute lung injury, and acute respiratory failure) in combat trauma patients in the military (U.S. or allied forces).

DATA EXTRACTION

Study years, design, location, number of patients, target outcomes as related to ALI/ARDS or related entities, and results were collected.

DATA SYNTHESIS

The initial search yielded 442 studies, with 22 ultimately included. Literature on ALI/ARDS comes mostly from retrospective data and case studies, with limited prospective studies. The incidence and prevalence of ALI/ARDS range from 3% to 33%, and mortality 12.8% to 33%. BLI, a known antecedent to ALI/ARDS, has an incidence and mortality ranging from 1.4% to 40% and 11% to 56%, respectively. Risk factors for ALI/ARDS include pulmonary injury, inhalation injury, blunt trauma, pneumonia, higher military injury severity score, higher injury severity score, higher fresh frozen plasma volumes, higher plasma and platelet volumes, the use of warm fresh whole blood, female sex, low blood pressure, and tachycardia. Literature has demonstrated the effectiveness in transportation of these patients and the utility of extracorporeal life support.

CONCLUSIONS

ALI/ARDS incidences and prevalences in modern conflict range from 3% to 33%, with mortality ranging from 12.8% to 33%. ALI/ARDS has been associated with injury severity metrics, injury type, resuscitative fluid amount and type, vital signs, and patient demographics. Studies are limited to mostly retrospective data, and more data are needed to better characterize these conditions.

Plasma Transfusion: History, Current Realities, and Novel Improvements

Traumatic hemorrhage is the leading cause of preventable death after trauma. Early transfusion of plasma and balanced transfusion have been shown to optimize survival, mitigate the acute coagulopathy of trauma, and restore the endothelial glycocalyx. There are a myriad of plasma formulations available worldwide, including fresh frozen plasma, thawed plasma, liquid plasma, plasma frozen within 24 h, and lyophilized plasma (LP). Significant equipoise exists in the literature regarding the optimal plasma formulation. LP is a freeze-dried formulation that was originally developed in the 1930s and used by the American and British military in World War II. It was subsequently discontinued due to risk of disease transmission from pooled donors. Recently, there has been a significant amount of research focusing on optimizing reconstitution of LP. Findings show that sterile water buffered with ascorbic acid results in decreased blood loss with suppression of systemic inflammation. We are now beginning to realize the creation of a plasma-derived formulation that rapidly produces the associated benefits without logistical or safety constraints. This review will highlight the history of plasma, detail the various types of plasma formulations currently available, their pathophysiological effects, impacts of storage on coagulation factors in vitro and in vivo, novel concepts, and future directions.

Is thromboelastography (TEG)-based resuscitation better than empirical 1:1 transfusion?

Thomboelastography (TEG) is a whole blood measure of coagulation which was originally described in the 1950s. However, it has only been in the last few decades that assays have become accessible and viable as a point-of-care test. Following the observation that hemorrhagic shock is associated with an intrinsic coagulopathy, TEG has been used as a method of diagnosing specific coagulation defects in order to direct individualized blood products resuscitation. An alternative transfusion strategy is the administration of fixed ratio products, a paradigm borne out of military experience. It is unknown which strategy is superior and this topic was debated at the 36th Annual Point/Counterpoint Acute Care Surgery Conference. The following article summarizes the discussants points of view along with a summary of the evidence.

Blast Scaling Parameters: Transitioning from Lung to Skull Base Metrics

Neurotrauma from blast exposure is one of the single most characteristic injuries of modern warfare. Understanding blast traumatic brain injury is critical for developing new treatment options for warfighters and civilians exposed to improvised explosive devices. Unfortunately, the pre-clinical models that are widely utilized to investigate blast exposure are based on archaic lung based parameters developed in the early 20th century. Improvised explosive devices produce a different type of injury paradigm than the typical mortar explosion. Protective equipment for the chest cavity has also improved over the past 100 years. In order to improve treatments, it is imperative to develop models that are based more on skull-based parameters. In this mini-review, we discuss the important anatomical and biochemical features necessary to develop a skull-based model.

[Efficacy of high versus low plasma: red blood cell ratio resuscitation in patients with severe trauma requiring massive blood transfusion: a meta-analysis]

OBJECTIVE

To evaluate the efficacy of high (≥1:2) and low (<1:2) plasma: red blood cell (RBC) ratio resuscitation in patients with severe trauma requiring massive blood transfusion.

METHODS

The databases including the Cochrane Library, Pubmed, Web of Science, and EMBASE were systemically searched for relevant studies published between January, 2009 and April, 2016. The selection of studies, assessment of methodological quality and data extraction were performed by two researchers independently according to the inclusion and exclusion criteria. The main endpoint was 24-h mortality, 30-day mortality and 24-h survival rate.

RESULTS

Five observational studies reporting outcomes of 1024 patients were included in this meta-analysis. Four studies documented civilian cases and one study had a military setting. No significant differences were found in the Injury Severity Score (ISS) between patient groups receiving high and low plasma: RBC ratio resuscitation. Compared with the low-ratio group, the patients with high-ratio resuscitation showed a significant reduction in the 24-h mortality rate (OR=0.35, 95%CI [0.25, 0.48], P<0.000 01) and the 30-day mortality rate (OR=0.55, 95%CI [0.41, 0.75], P=0.0001). An increased survival rate was observed in patients receiving high plasma: RBC ratio resuscitation within the initial 24 h following the trauma (HR=2.34, 95%CI [1.46, 3.73], P=0.00001).

CONCLUSION

Raising the plasma: RBC ratio to 0.5 or higher may decrease the mortality rate of the patients with severe trauma who need massive blood transfusion.

Tactical damage control resuscitation in austere military environments

BACKGROUND

Despite the early uses of tourniquets and haemostatic dressings, blood loss still accounts for the vast majority of preventable deaths on the battlefield. Over the last few years, progress has been made in the management of such injuries, especially with the use of damage control resuscitation concepts. The early application of these procedures, on the field, may constitute the best opportunity to improve survival from combat injury during remote operations.

DATA SOURCES

Currently available literature relating to trauma-induced coagulopathy treatment and far-forward transfusion was identified by searches of electronic databases. The level of evidence and methodology of the research were reviewed for each article. The appropriateness for field utilisation of each medication was then discussed to take into account the characteristics of remote military operations.

CONCLUSIONS

In tactical situations, in association with haemostatic procedures (tourniquet, suture, etc), tranexamic acid should be the first medication used according to the current guidelines. The use of fibrinogen concentrate should also be considered for patients in haemorrhagic shock, especially if point-of-care (POC) testing of haemostasis or shock severity is available. If POC evaluation is not available, it seems reasonable to still administer this treatment after clinical assessment, particularly if the evacuation is delayed. In this situation, lyophilised plasma may also be given as a resuscitation fluid while respecting permissive hypotension. Whole blood transfusion in the field deserves special attention. In addition to the aforementioned treatments, if the field care is prolonged, whole blood transfusion must be considered if it does not delay the evacuation.

Prehospital use of plasma: the blood bankers' perspective

At the 2013 Traumatic Hemostasis and Oxygenation Research Network's Remote Damage Control Resuscitation symposium, a panel of senior blood bankers with both civilian and military background was invited to discuss their willingness and ability to supply prehospital plasma for resuscitation of massively bleeding casualties and to comment on the optimal preparations for such situations. Available evidence indicates that prehospital use of plasma may improve remote damage control resuscitation, although level I evidence is lacking. This practice is well established in several military services and is also being introduced in civilian settings. There are few, if any, clinical contraindications to the prehospital use of plasma, except for blood group incompatibility and the danger of transfusion-induced acute lung injury, which can be circumvented in various ways. However, the choice of plasma source, plasma preparation, and logistics including stock management require consideration. Staff training should include hemovigilance and traceability as well as recognition and management of eventual adverse effects. Prehospital use of plasma should occur within the framework of clinical algorithms and prospective clinical studies. Clinicians have an ethical responsibility to both patients and donors; therefore, the introduction of new clinical capabilities of transfusion must be safe, efficacious, and sustainable. The panel agreed that although these problems need further attention and scientific studies, now is the time for both military and civilian transfusion systems to prepare for prehospital use of plasma in massively bleeding casualties.

Thromboelastogram evaluation of the impact of hypercoagulability in trauma patients

INTRODUCTION

Admission hypocoagulability has been associated with negative outcomes after trauma. The purpose of this study was to determine the impact of hypercoagulability after trauma on the need for blood product transfusion and mortality.

METHODS

Injured patients meeting our level I trauma center's highest activation criteria had a thromboelastography (TEG) performed at admission, +1 h, +2 h, and +6 h using citrated blood. Hypercoagulability was defined as any TEG parameter in the hypercoagulable range, and hypocoagulability as any parameter in the hypocoagulable range. Patients were followed up prospectively throughout their hospital course.

RESULTS

A total of 118 patients were enrolled: 26.3% (n = 31) were hypercoagulable, 55.9% (n = 66) had a normal TEG profile, and 17.8% (n = 21) were hypocoagulable. After adjusting for differences in demographics and clinical data, hypercoagulable patients were less likely to require un-cross-matched blood (11.1% for hypercoagulable vs. 20.4% for normal vs. 45.7% for hypocoagulable, adjusted P = 0.004). Hypercoagulable patients required less total blood products, in particular, plasma at 6 h (0.1 [SD, 0.4] U for hypercoagulable vs. 0.7 [SD, 1.9] U for normal vs. 4.3 [SD, 6.3] U for hypocoagulable, adjusted P < 0.001) and 24 h (0.2 [SD, 0.6] U for hypercoagulable vs. 1.1 [SD, 2.9] U for normal vs. 8.2 [SD, 19.3] U for hypocoagulable, adjusted P < 0.001). Hypercoagulable patients had lower 24-h mortality (0.0% vs. 5.5% vs. 27.8%, adjusted P < 0.001) and 7-day mortality (0.0% vs. 5.5% vs. 36.1%, adjusted P < 0.001). Bleeding-related deaths were less likely in the hypercoagulable group (0.0% vs. 1.8% vs. 25.0%, adjusted P < 0.001).

CONCLUSIONS

Approximately a quarter of trauma patients presented in a hypercoagulable state. Hypercoagulable patients required less blood products, in particular plasma. They also had a lower 24-h and 7-day mortality and lower rates of bleeding-related deaths. Further evaluation of the mechanism responsible for the hypercoagulable state and its implications on outcome is warranted.

Midterm effects of fluid resuscitation strategies in an experimental model of lung contusion and hemorrhagic shock

BACKGROUND

This study compared three different fluid resuscitation strategies in terms of respiratory tolerance and hemodynamic efficacy in a pig model of blunt chest trauma with lung contusion and controlled hemorrhagic shock. We hypothesized that the choice of fluid resuscitation strategy (type and amount of fluids) may impact differently contused lungs in terms of extravascular lung water (EVLW) 20 h after trauma.

METHODS

Anesthetized female pigs (n = 5/group) received five bolt shots to the right thoracic cage and allowed to hemorrhage for 30 min, with 25 to 30 mL/kg of blood loss. Pigs were randomly assigned to resuscitation groups that maintained a minimum mean arterial blood pressure of 70 mmHg with one of three methods: normal saline (NS), unrestricted normal saline; NOREPI, low-volume normal saline with norepinephrine; or HS-HES, hypertonic saline with hydroxyethyl starch. Control pigs were anesthetized, but received no injury or treatment. After 20 h, animals were killed to measure EVLW by gravimetry.

RESULTS

Fluid loading was significantly different in each group. All three treatment groups had higher EVLW than controls. Moderate, bilateral pulmonary edema was observed in the NS and HS-HES groups. The three treatment groups showed similar reductions in oxygenation. Static pulmonary compliance was diminished in the NS and HS-HES groups, but compliance was similar in NOREPI and control groups. The NOREPI group had pathological lactate levels.

CONCLUSIONS

This study demonstrated the impact of fluid resuscitation on contused lungs. Twenty hours after the trauma, all three resuscitation approaches showed modest clinical consequences, with moderate lung edema and reduced compliance in response to the infused volume.

Freeze-dried plasma at the point of injury: from concept to doctrine

While early plasma transfusion for the treatment of patients with ongoing major hemorrhage is widely accepted as part of the standard of care in the hospital setting, logistic constraints have limited its use in the out-of-hospital setting. Freeze-dried plasma (FDP), which can be stored at ambient temperatures, enables early treatment in the out-of-hospital setting. Point-of-injury plasma transfusion entails several significant advantages over currently used resuscitation fluids, including the avoidance of dilutional coagulopathy, by minimizing the need for crystalloid infusion, beneficial effects on endothelial function, physiological pH level, and better maintenance of intravascular volume compared with crystalloid-based solutions. The Israel Defense Forces Medical Corps policy is that plasma is the resuscitation fluid of choice for selected, severely wounded patients and has thus included FDP as part of its armamentarium for use at the point of injury by advanced life savers, across the entire military. We describe the clinical rationale behind the use of FDP at the point-of-injury, the drafting of the administration protocol now being used by Israel Defense Forces advanced life support providers, the process of procurement and distribution, and preliminary data describing the first casualties treated with FDP at the point of injury. It is our hope that others will be able to learn from our experience, thus improving trauma casualty care around the world.

Reducing the burden of acute respiratory distress syndrome: the case for early intervention and the potential role of the emergency department

The mortality for acute respiratory distress syndrome (ARDS) remains unacceptably high. Success in clinical trials has been limited, resulting in a lack of effective therapies to treat the syndrome. The projected increase in mechanically ventilated patients and global need for critical care services suggests that the clinical and research landscape in ARDS can no longer be confined to the intensive care unit. A demonstrable minority of patients present to the emergency department (ED) with ARDS, and ARDS onset typically occurs shortly after intensive care unit admission. Furthermore, the ED is an entry point for many of the highest-risk patients for ARDS development and progression. These facts, combined with prolonged lengths of stay in the ED, suggest that the ED could represent a window of opportunity for treatment and preventive strategies, as well as clinical trial enrollment. This review aims to discuss some of the potential strategies that may prevent or alter the trajectory of ARDS, with a focus on the potential role the ED could play in reducing the burden of this syndrome.