Transfusion strategies and development of acute respiratory distress syndrome in combat casualty care

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.

Prolonged Mechanical Ventilation in Pediatric Trauma Patients in a Combat Zone

OBJECTIVES

It is well known that polytrauma can lead to acute lung injury. Respiratory failure has been previously observed in combat trauma, but not reported in children, who account for over 11% of bed days at deployed Military Treatment Facilities (MTFs) using significant resources. We seek to identify risk factors associated with prolonged mechanical ventilation (PMV) which is important in resource planning and allocation in austere environments.

DESIGN

Retrospective review of prospectively collected data within the United States Department of Defense Trauma Registry.

SETTING

Deployed U.S. MTFs in Iraq and Afghanistan from 2007 to 2016.

PATIENTS

All pediatric subjects who required at least 1 day of mechanical ventilation, excluding patients who died on day 0.

INTERVENTIONS

PMV was defined using the Youden index for mortality. A multivariable logistic regression model was then performed to identify factors associated with PMV.

MEASUREMENTS AND MAIN RESULTS

The Youden index identified greater than or equal to 6 days as the cutoff for PMV. Of the 859 casualties included in the analysis, 154 (17.9%) had PMV. On univariable analysis, age, severe injury to the thorax and skin, 24-hour volume/kg administration of crystalloids, colloids, platelets, plasma, and packed RBCs was associated with PMV. In the multivariable model, odds ratios (95% CI) associated with PMV were crystalloids 1.04 (1.02-1.07), colloids 1.24 (1.04-1.49), platelets 1.03 (1.01-1.05), severe injury to the thorax 2.24 (1.41-3.48), and severe injury to the skin 4.48 (2.72-7.38). Model goodness-of-fit r2 was 0.14.

CONCLUSIONS

In this analysis of factors associated with PMV in pediatric trauma patients in a combat zone, in addition to severe injury to skin and thorax, we found that administration of crystalloids, colloids, and platelets was independently associated with greater odds of PMV. Our findings will help inform resource planning and suggest potential resuscitation strategies for future studies.

Analysis of extracorporeal membrane oxygenation in trauma patients with acute respiratory distress syndrome: A case series

BACKGROUND

Thoracic trauma is the most common injury in polytrauma patients. Often associated with the development of an acute respiratory distress syndrome (ARDS), conservative treatment options are very restricted and reach their limits quickly.

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is a wellestablished therapy in cardio-thoracic surgery and internal medicine intensive care units. The purpose of this study is to analyse the potential benefit of ECMO therapy in ARDS treatment in polytrauma patients.

DESIGN

Retrospective case series.

SETTING

Level 1 trauma centre, Germany, 04/2011-04/2019.

PATIENTS

Nineteen patients with ARDS treated with a veno-venous ECMO system.

MAIN OUTCOME MEASURES

This study focused on the time leading to therapy initiation, the severity of thoracic and overall injury. The Sequential Organ Failure Assessment (SOFA) Score, the Murray Score, the Abbreviated Injury Scale (AIS) 2005 level and the Injury Severity Score (ISS) were analysed. The results were analysed regarding survival and death.

RESULTS

The survival rate was 53%. The ISS was the same for survivors and deceased patients (p = 0.604). Early initiation of ECMO therapy showed a significant trend for survivors (p = 0.071). The SOFA Score level before ECMO therapy was significantly lower in the survivors than in those who died (p = 0.035). The AISThorax level for survivors showed a significantly higher score level than the one for deceased patients (p = 0.05).

CONCLUSION

ECMO therapy in polytrauma patients is a safe and effective option, in particular when used early in ARDS treatment. The overall severity of organ failure determined the likelihood of survival rather than the thoracic trauma itself.

Intense Light Pretreatment Improves Hemodynamics, Barrier Function and Inflammation in a Murine Model of Hemorrhagic Shock Lung

INTRODUCTION

Hemorrhagic shock is a primary injury amongst combat casualties. Hemorrhagic shock can lead to acute lung injury, which has a high mortality rate. Based on studies showing the role of intense light for organ-protection, we sought to evaluate if intense light pretreatment would be protective in a murine model of hemorrhagic shock lung.

MATERIALS AND METHODS

After exposure to standard room light or to intense light (10 000 LUX), mice were hemorrhaged for 90 minutes to maintain a mean arterial pressure (MAP) of 30-35 mmHg. Mice were then resuscitated with their blood and a NaCl infusion at a rate of 0.2 ml/h over a 3-hour period. During resuscitation, blood pressure was recorded. At the end of resuscitation, bronchoalveolar lavage was analyzed for alveolar epithelial barrier function and inflammation. To get insight into the relevance of intense light for humans, we performed a proteomics screen for lung injury biomarkers in plasma from healthy volunteers following intense light therapy.

RESULTS

We found that intense light pretreated mice had improved hemodynamics and significantly lower albumin, IL-6, and IL-8 levels in their bronchoalveolar lavage than controls. We further discovered that intense light therapy in humans significantly downregulated proinflammatory plasma proteins that are known to cause acute lung injury.

CONCLUSIONS

Our data demonstrate that mice exposed to intense light before hemorrhagic shock lung have less lung inflammation and improved alveolar epithelial barrier function. We further show that intense light therapy downregulates lung injury promoting proteins in human plasma. Together, these data suggest intense light as a possible strategy to ameliorate the consequences of a hemorrhagic shock on lung injury.

Impact of raising serum myoglobin on resuscitation of trauma patients with high injury severity score (ISS)

INTRODUCTION

Recent studies recommend limiting the amount of crystalloid perfused during resuscitation for trauma patients. Severely injured patients sustain extensive muscle damage with subsequent high serum myoglobin levels precipitating acute renal injury if not treated immediately. To timely identify patients at risk of acute renal injury, we proposed determining the strength of the correlation between the American College of Surgeons-defined injury severity score with serum and urine myoglobin level in the early hours of arrival to the emergency department to determine the patient at higher risk of raising serum myoglobin level and subsequent renal injury.

METHOD

A retrospective analysis was conducted at a 400-bed community teaching hospital with a level 2 trauma section and annual admission of 750-800 patients using the data in the trauma registry (2010-2017). Patients with an injury severity score of 15 or above were selected, and Student t test and Pearson correlation 2-tailed analysis were used to identify the relationship with serum myoglobin.

RESULT

There were 306 patients total, with 200 men (70.3%) and 106 women (29.7%) and a mean age of 60.64 (SD = 23.6) (range 18-96) years. The mean injury severity score was 22.3 (SD = 8.5) (range 16-75). The median level of serum myoglobin in the first 24 hours of admission was 848.56 ng/mL (range 22-11,197). There was a strong and significant correlation between the 2 variables (r = 0.397, P < .0001).

CONCLUSION

The appearance of urine myoglobin with serum level of 39 ng/mL suggests that with higher injury severity score, the potential for acute kidney injury is likely and should be addressed early in the patient management.

Early Identification of Acute Lung Injury in a Porcine Model of Hemorrhagic Shock

BACKGROUND

Acute lung injury (ALI) is a frequent complication after severe trauma. Lung-protective ventilation strategies and damage control resuscitation have been proposed for the prevention of ALI; however, there are no clinical or laboratory parameters to predict who is at risk of developing ALI after trauma. In the present study, we explored pulmonary inflammatory markers as a potential predictor of ALI using a porcine model of hemorrhagic shock.

MATERIALS AND METHODS

Female swine were randomized to mechanical ventilation with low tidal volume (V_T) (6 mL/kg) or high V_T (12 mL/kg). After equilibration, animals underwent pressure-controlled hemorrhage (mean arterial pressure [MAP] 35 ± 5 mmHg) for 1 h, followed by resuscitation with fresh whole blood or Hextend. They were maintained at MAP of 50 ± 5 mmHg for 3 h in the postresuscitation phase. Bronchoalveolar lavage fluids were collected hourly and analyzed for inflammatory markers. Lung samples were taken, and porcine neutrophil antibody staining was used to evaluate the presence of neutrophils. ELISA evaluated serum porcine surfactant protein D levels. Sham animals were used as negative controls.

RESULTS

Pigs that underwent hemorrhagic shock had higher heart rates, lower cardiac output, lower MAPs, and worse acidosis compared with sham at the early time points (P < 0.05 each). There were no significant differences in central venous pressure or pulmonary capillary wedge pressure between groups. Pulmonary neutrophil infiltration, as defined by neutrophil antibody staining on lung samples, was greater in the shock groups regardless of resuscitation fluid (P < 0.05 each). Bronchoalveolar lavage fluid neutrophil levels were not different between groups. There were no differences in levels of porcine surfactant protein D between groups at any time points, and the levels did not change over time in each respective group.

CONCLUSIONS

Our study demonstrates the reproducibility of a porcine model of hemorrhagic shock that is consistent with physiologic changes in humans in hemorrhagic shock. Pulmonary neutrophil infiltration may serve as an early marker for ALI; however, the practicality of this finding has yet to be determined.

Acute Respiratory Distress Syndrome: Etiology, Pathogenesis, and Summary on Management

The acute respiratory distress syndrome (ARDS) has multiple causes and is characterized by acute lung inflammation and increased pulmonary vascular permeability, leading to hypoxemic respiratory failure and bilateral pulmonary radiographic opacities. The acute respiratory distress syndrome is associated with substantial morbidity and mortality, and effective treatment strategies are limited. This review presents the current state of the literature regarding the etiology, pathogenesis, and management strategies for ARDS.

Acute Respiratory Failure

Acute respiratory distress syndrome (ARDS) is a condition affecting critically ill patients, characterized by pulmonary inflammation and defects in oxygenation due to either direct or indirect injury to the lungs. These guidelines will define the diagnosis and management of ARDS, particularly among combat casualties and patients in the deployed environment. The cornerstone of management of ARDS involves maintaining adequate oxygenation while avoiding further pulmonary injury through lung-protective ventilation. Additional strategies for advanced respiratory failure, such as prone positioning, neuromuscular blockade, and extracorporeal membrane oxygenation will be reviewed here as well. Particularly important to the care of the patient with ARDS in the deployed environment is a familiarity with the challenges and indications for transport/aeromedical evacuation.

Late immune consequences of combat trauma: a review of trauma-related immune dysfunction and potential therapies

With improvements in personnel and vehicular body armor, robust casualty evacuation capabilities, and damage control resuscitation strategies, more combat casualties are surviving to reach higher levels of care throughout the casualty evacuation system. As such, medical centers are becoming more accustomed to managing the deleterious late consequences of combat trauma related to the dysregulation of the immune system. In this review, we aim to highlight these late consequences and identify areas for future research and therapeutic strategies. Trauma leads to the dysregulation of both the innate and adaptive immune responses, which places the injured at risk for several late consequences, including delayed wound healing, late onset sepsis and infection, multi-organ dysfunction syndrome, and acute respiratory distress syndrome, which are significant for their association with the increased morbidity and mortality of wounded personnel. The mechanisms by which these consequences develop are complex but include an imbalance of the immune system leading to robust inflammatory responses, triggered by the presence of damage-associated molecules and other immune-modifying agents following trauma. Treatment strategies to improve outcomes have been difficult to develop as the immunophenotype of injured personnel following trauma is variable, fluid and difficult to determine. As more information regarding the triggers that lead to immune dysfunction following trauma is elucidated, it may be possible to identify the immunophenotype of injured personnel and provide targeted treatments to reduce the late consequences of trauma, which are known to lead to significant morbidity and mortality.

Immunomodulatory effects of plasma products on monocyte function in vitro

BACKGROUND

Restoration of a balanced innate immune response is paramount to recovery from critical injury. Plasma transfusion may modulate innate immune responses; however, little is known about the immunomodulatory potential of various plasma products. We conducted in vitro experiments to determine the effects of fresh frozen plasma, thawed plasma, solvent/detergent plasma, and an investigational spray-dried solvent/detergent plasma product on monocyte function.

METHODS

Monocytes were isolated from healthy adult volunteers and cocultured with aliquots of autologous plasma (control), fresh frozen plasma, thawed plasma, solvent/detergent treated plasma, or spray-dried solvent/detergent plasma. Monocyte function was assessed by cytokine production with and without lipopolysaccharide (LPS) stimulation, and flow cytometric assessment of HLA-DR cell surface expression.

RESULTS

Monocyte cytokine production was not significantly altered after exposure to fresh frozen plasma or thawed plasma. In the absence of LPS, spray-dried solvent/detergent plasma exposure resulted in markedly increased IL-8 production compared to other plasma groups and controls (p = 0.01, analysis of variance [ANOVA]). Likewise, spray-dried SD plasma exposure resulted in higher LPS-induced IL-8, TNFα, and IL-1β production compared with autologous plasma controls (p < 0.0001; p < 0.0001, p = 0.002, respectively; ANOVA). LPS-induced IL-8 and TNFα production was lowest after exposure to solvent/detergent plasma (p < 0.0001, ANOVA).

CONCLUSION

Exposure to spray-dried solvent/detergent plasma resulted in marked augmentation of monocyte inflammatory cytokine production. Solvent/detergent plasma exposure resulted in the lowest cytokine production, suggesting lower immunomodulatory potential. Further work is needed to determine how these in vitro findings may translate to the bedside.

Washing or filtering of blood products does not improve outcome in a rat model of trauma and multiple transfusion

BACKGROUND

Transfusion is associated with organ failure and nosocomial infection in trauma patients, which may be mediated by soluble bioactive substances in blood products, including extracellular vesicles (EVs). We hypothesize that removing EVs, by washing or filtering of blood products, reduces organ failure and improves host immune response.

MATERIALS AND METHODS

Blood products were prepared from syngeneic rat blood. EVs were removed from RBCs and platelets by washing. Plasma was filtered through a 0.22‐μm filter. Rats were traumatized by crush injury to the intestines and liver, and a femur was fractured. Rats were hemorrhaged until a mean arterial pressure of 40 mm Hg and randomized to receive resuscitation with standard or washed/filtered blood products, in a 1:1:1 ratio. Sham controls were not resuscitated. Ex vivo whole blood stimulation tests were performed and histopathology was done.

RESULTS

Washing of blood products improved quality metrics compared to standard products. Also, EV levels reduced by 12% to 77%. The coagulation status, as assessed by thromboelastometry, was deranged in both groups and normalized during transfusion, without significant differences. Use of washed/filtered products did not reduce organ failure, as assessed by histopathologic score and biochemical measurements. Immune response ex vivo was decreased following transfusion compared to sham but did not differ between transfusion groups.

CONCLUSION

Filtering or washing of blood products improved biochemical properties and reduced EV counts, while maintaining coagulation abilities. However, in this trauma and transfusion model, the use of optimized blood components did not attenuate organ injury or immune suppression.

Platelet transfusion increases risk for acute respiratory distress syndrome in non-massively transfused blunt trauma patients

PURPOSE

While damage control resuscitation is known to confer a survival advantage in severely injured patients, high-ratio blood component therapy should be initiated only in carefully selected trauma patients, due to the morbidity associated with blood product use. With this project, we aim to identify the effect of platelet transfusion in non-massively transfused bluntly injured patients.

METHODS

The Glue Grant database was retrospectively queried and severely injured blunt trauma patients who underwent non-massive transfusion were identified. Patients were divided into quartiles depending on platelet volume they were transfused in the first 48 h. Outcomes of interest included mortality; ventilator, Intensive Care Unit (ICU) and hospital length of stay (LOS); infectious and non-infectious complications. Multivariable regression models were fitted for these outcomes, controlling for age, pre-existing comorbidities, injury severity, acute physiologic derangement, neurologic injury burden, and other fluid and blood product resuscitation.

RESULTS

There was no difference in mortality, LOS, or the incidence of multi-organ failure and infectious complications. However, patients receiving ≥ 250 mL of platelets were more likely to develop acute respiratory distress syndrome (ARDS) compared to those who received < 250 mL [odds ratio 1.91 (95% CI 1.10-3.33, p = 0.022)].

CONCLUSIONS

Pre-emptive platelet transfusion should be avoided in non-massively transfused blunt injury victims in the absence of true or functional thrombocytopenia, as it increases risk for ARDS with no survival benefit.

Lung Protective Effects of Low-Volume Resuscitation and Pharmacologic Treatment of Swine Subjected to Polytrauma and Hemorrhagic Shock

Hemorrhage is a common cause of death in the battlefield. Valproic acid (VPA) has been associated with improved outcomes in multiple models of trauma, when combined with isotonic fluid resuscitation. However, isotonic fluid administered in this setting is logistically impractical and may be associated with complications. In this study, we sought to evaluate the feasibility and immunologic impact of combining VPA treatment with low-volume hypertonic saline (HTS). In vivo: female Yorkshire swine were subjected to hemorrhage (40% total blood volume) and polytrauma (rib fracture and delayed liver injury). Animals were kept in shock for 30 minutes and resuscitated with (1) normal saline (NS, 3× hemorrhaged volume), (2) HTS (7.5% saline, 4 mL/kg), or (3) HTS + VPA (4 mg/kg; 150 mg/kg; n = 3/cohort). After 18 hours of observation, animals were euthanized and the lungs evaluated for acute injury and expression of myeloperoxidase (MPO) and caveolin-1 (Cav-1). In vitro: human umbilical vein endothelial cells (HUVECs) were exposed to anoxic conditions (5% CO₂, 95% N₂) for 16 hours in (1) normosmotic, (2) hyperosmotic (400 mOsm), or (3) hyperosmotic + VPA (4 mM) media. Immunohistochemistry and Western blots were performed to determine Cav-1 expression. Lungs from VPA-treated animals demonstrated decreased acute injury, MPO expression, and endothelial expression of Cav-1 when compared to lungs from animals resuscitated with NS or HTS alone. Similarly, HUVECs cultured in hyperosmotic media containing VPA demonstrated decreased expression of Cav-1. This study demonstrates that combined treatment with VPA and HTS is a viable strategy in hemorrhagic shock and polytrauma. Attenuation of lung injury following VPA treatment may be related to modulation of the inflammatory response.

Mesenchymal stem cell-derived extracellular vesicles attenuate pulmonary vascular permeability and lung injury induced by hemorrhagic shock and trauma

BACKGROUND

Mesenchymal stem cells (MSCs) have been shown to mitigate vascular permeability in hemorrhagic shock (HS) and trauma-induced brain and lung injury. Mechanistically, paracrine factors secreted from MSCs have been identified that can recapitulate many of the potent biologic effects of MSCs in animal models of disease. Interestingly, MSC-derived extracellular vesicles (EVs), contain many of these key soluble factors, and have therapeutic potential independent of the parent cells. In this study we sought to determine whether MSC-derived EVs (MSC EVs) could recapitulate the beneficial therapeutic effects of MSCs on lung vascular permeability induced by HS in mice.

METHODS

Mesenchymal stem cell EVs were isolated from human bone marrow-derived MSCs by ultracentrifugation. A mouse model of fixed pressure HS was used to study the effects of shock, shock + MSCs and shock + MSC EVs on lung vascular endothelial permeability. Mice were administered MSCs, MSC EVs, or saline IV. Lung tissue was harvested and assayed for permeability, RhoA/Rac1 activation, and for differential phosphoprotein expression. In vitro, human lung microvascular cells junctional integrity was evaluated by immunocytochemistry and endothelial cell impedance assays.

RESULTS

Hemorrhagic shock-induced lung vascular permeability was significantly decreased by both MSC and MSC EV infusion. Phosphoprotein profiling of lung tissue revealed differential activation of proteins and pathways related to cytoskeletal rearrangement and regulation of vascular permeability by MSCs and MSC EVs. Lung tissue from treatment groups demonstrated decreased activation of the cytoskeletal GTPase RhoA. In vitro, human lung microvascular cells, MSC CM but not MSC-EVs prevented thrombin-induced endothelial cell permeability as measured by electrical cell-substrate impedance sensing system and immunocytochemistry of VE-cadherin and actin.

CONCLUSION

Mesenchymal stem cells and MSC EVs modulate cytoskeletal signaling and attenuate lung vascular permeability after HS. Mesenchymal stem cell EVs may potentially be used as a novel "stem cell free" therapeutic to treat HS-induced lung injury.

Treatment of combined traumatic brain injury and hemorrhagic shock with fractionated blood products versus fresh whole blood in a rat model

INTRODUCTION

Treatment of combined traumatic brain injury and hemorrhagic shock, poses a particular challenge due to the possible conflicting consequences. While restoring diminished volume is the treatment goal for hypovolemia, maintaining adequate cerebral perfusion pressure and avoidance of secondary damage remains a treatment goal for the injured brain. Various treatment modalities have been proposed, but the optimal resuscitation fluid and goals have not yet been clearly defined. A growing body of evidence suggests that in hypovolemic shock, resuscitation with fresh whole blood (FWB) may be superior to component therapy without platelets (which are likely to be unavailable in the pre-hospital setting). Nevertheless, the effects of this approach have not been studied in the combined injury. Previously, in a rat model of combined injury we have found that mild resuscitation to MABP of 80 mmHg with FWB is superior to fluid resuscitation or aggressive resuscitation with FWB. In this study, we investigate the physiological and neurological outcomes in a rat model of combined traumatic brain injury (TBI) and hypovolemic shock, submitted to treatment with varying amounts of FWB, compared to similar resuscitation goals with fractionated blood products-red blood cells (RBCs) and plasma in a 1:1 ratio regimen.

MATERIALS AND METHODS

40 male Lewis rats were divided into control and treatment groups. TBI was inflicted by a free-falling rod on the exposed cranium. Hypovolemia was induced by controlled hemorrhage of 30% blood volume. Treatment groups were treated either with fresh whole blood or with RBC + plasma in a 1:1 ratio, achieving a resuscitation goal of a mean arterial blood pressure (MAP) of 80 mmHg at 15 min. MAP was assessed at 60 min, and neurological outcomes and mortality in the subsequent 24 h.

RESULTS

At 60 min, hemodynamic parameters were improved compared to controls, but not significantly different between treatment groups. Survival rates at 48 h were 100% for both of the mildly resuscitated groups (MABP 80 mmHg) with FWB and RBC + plasma. The best neurological outcomes were found in the group mildly resuscitated with FWB and were better when compared to resuscitation with RBC + plasma to the same MABP goal (FWB: Neurological Severity Score (NSS) 6 ± 2, RBC + plasma: NSS 10 ± 2, p = 0.02).

CONCLUSIONS

In this study, we find that mild resuscitation with goals of restoring MAP to 80 mmHg (which is lower than baseline) with FWB, provided better hemodynamic stability and survival. However, the best neurological outcomes were found in the group resuscitated with FWB. Thus, we suggest that resuscitation with FWB is a feasible modality in the combined TBI + hypovolemic shock scenario, and may result in improved outcomes compared to platelet-free component blood products.

Incidence, risk factors, and mortality associated with acute respiratory distress syndrome in combat casualty care

BACKGROUND

The overall incidence and mortality of acute respiratory distress syndrome (ARDS) in civilian trauma settings have decreased over the past four decades; however, the epidemiology and impact of ARDS on modern combat casualty care are unknown. We sought to determine the incidence, risk factors, resource utilization, and mortality associated with ARDS in current combat casualty care.

METHODS

This was a retrospective review of mechanically ventilated US combat casualties within the Department of Defense Trauma Registry (formerly the Joint Theater Trauma Registry) during Operation Iraqi Freedom/Enduring Freedom (October 2001 to August 2008) for ARDS development, resource utilization, and mortality.

RESULTS

Of 18,329 US Department of Defense Trauma Registry encounters, 4,679 (25.5%) required mechanical ventilation; ARDS was identified in 156 encounters (3.3%). On multivariate logistic regression, ARDS was independently associated with female sex (odds ratio [OR], 2.62; 95% confidence interval [CI], 1.21-5.71; p = 0.02), higher military-specific Injury Severity Score (Mil ISS) (OR, 4.18; 95% CI, 2.61-6.71; p < 0.001 for Mil ISS ≥25 vs. <15), hypotension (admission systolic blood pressure <90 vs. ≥90 mm Hg; OR, 1.76; 95% CI, 1.07-2.88; p = 0.03), and tachycardia (admission heart rate ≥90 vs. <90 beats per minute; OR, 1.53; 95% CI, 1.06-2.22; p = 0.02). Explosion injury was not associated with increased risk of ARDS. Critical care resource utilization was significantly higher in ARDS patients as was all-cause hospital mortality (ARDS vs. no ARDS, 12.8% vs. 5.9%; p = 0.002). After adjustment for age, sex, injury severity, injury mechanism, Mil ISS, hypotension, tachycardia, and admission Glasgow Coma Scale score, ARDS remained an independent risk factor for death (OR, 1.99; 95% CI, 1.12-3.52; p = 0.02).

CONCLUSIONS

In this large cohort of modern combat casualties, ARDS risk factors included female sex, higher injury severity, hypotension, and tachycardia, but not explosion injury. Patients with ARDS also required more medical resources and were at greater risk of death compared with patients without ARDS. Thus, ARDS remains a significant complication in current combat casualty care.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Outcomes Related to the Use of Frozen Plasma or Pooled Solvent/Detergent-Treated Plasma in Critically Ill Children

OBJECTIVE

To determine if the use of fresh frozen plasma/frozen plasma 24 hours compared to solvent detergent plasma is associated with international normalized ratio reduction or ICU mortality in critically ill children.

DESIGN

This is an a priori secondary analysis of a prospective, observational study. Study groups were defined as those transfused with either fresh frozen plasma/frozen plasma 24 hours or solvent detergent plasma. Outcomes were international normalized ratio reduction and ICU mortality. Multivariable logistic regression was used to determine independent associations.

SETTING

One hundred one PICUs in 21 countries.

PATIENTS

All critically ill children admitted to a participating unit were included if they received at least one plasma unit during six predefined 1-week (Monday to Friday) periods. All children were exclusively transfused with either fresh frozen plasma/frozen plasma 24 hours or solvent detergent plasma.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 443 patients enrolled in the study. Twenty-four patients (5%) were excluded because no plasma type was recorded; the remaining 419 patients were analyzed. Fresh frozen plasma/frozen plasma 24 hours group included 357 patients, and the solvent detergent plasma group included 62 patients. The median (interquartile range) age and weight were 1 year (0.2-6.4) and 9.4 kg (4.0-21.1), respectively. There was no difference in reason for admission, severity of illness score, pretransfusion international normalized ratio, or lactate values; however, there was a difference in primary indication for plasma transfusion (p < 0.001). There was no difference in median (interquartile range) international normalized ratio reduction, between fresh frozen plasma/frozen plasma 24 hours and solvent detergent plasma study groups, -0.2 (-0.4 to 0) and -0.2 (-0.3 to 0), respectively (p = 0.80). ICU mortality was lower in the solvent detergent plasma versus fresh frozen plasma/frozen plasma 24 hours groups, 14.5% versus 29.1%%, respectively (p = 0.02). Upon adjusted analysis, solvent detergent plasma transfusion was independently associated with reduced ICU mortality (odds ratio, 0.40; 95% CI, 0.16-0.99; p = 0.05).

CONCLUSIONS

Solvent detergent plasma use in critically ill children may be associated with improved survival. This hypothesis-generating data support a randomized controlled trial comparing solvent detergent plasma to fresh frozen plasma/frozen plasma 24 hours.

Limited Blood Transfusions Are Safe in Orthopaedic Trauma Patients

OBJECTIVES

Controversy exists over association of blood transfusions with complications. The purpose was to assess effects of limited transfusions on complication rates and hospital course.

SETTING

Level 1 trauma center.

PATIENTS AND METHODS

Three hundred seventy-one consecutive patients with Injury Severity Score ≥16 underwent fixation of fractures of spine (n = 111), pelvis (n = 72), acetabulum (n = 57), and/or femur (n = 179). Those receiving >3 units of packed red blood cell were excluded.

MAIN OUTCOME MEASUREMENTS

Fracture type, associated injuries, treatment details, ventilation time, complications, and hospital stay were prospectively recorded.

RESULTS

Ninety-eight patients with 107 fractures received limited transfusion, and 119 patients with 123 fractures were not transfused. The groups did not differ in age, fracture types, time to fixation, or associated injuries. Lowest hematocrit was lower in the transfused group (22.8 vs. 30.0, P < 0.0001). Surgical duration (3:23 vs. 2:28) and estimated blood loss (462 vs. 211 mL) were higher in transfused patients (all P < 0.003). Pulmonary complications occurred in 12% of transfused and 4% of nontransfused, (P = 0.10). Mean days of mechanical ventilation (2.51 vs. 0.45), intensive care unit days (4.5 vs. 1.5) and total hospital stay (8.8 vs. 5.7) were higher in transfused patients (all P ≤ 0.006). After multivariate analysis, limited transfusion was associated with increased hospital and intensive care unit stays and mechanical ventilation time, but not with complications.

CONCLUSIONS

Patients receiving ≤3 units of packed red blood cell had lower hematocrit and greater surgical burden, but no difference in complications versus the nontransfused group. Limited blood transfusions are likely safe, excepting a possible association with longer mechanical ventilation times and hospital stays.

LEVEL OF EVIDENCE

Therapeutic level III. See Instructions for Authors for a complete description of levels of evidence.

Misclassification of acute respiratory distress syndrome after traumatic injury: The cost of less rigorous approaches

BACKGROUND

Adherence to rigorous research protocols for identifying adult respiratory distress syndrome (ARDS) after trauma is variable. To examine how misclassification of ARDS may bias observational studies in trauma populations, we evaluated the agreement of two methods for adjudicating ARDS after trauma: the current gold standard, direct review of chest radiographs and review of dictated radiology reports, a commonly used alternative.

METHODS

This nested cohort study included 123 mechanically ventilated patients between 2005 and 2008, with at least one PaO2/FIO2 less than 300 within the first 8 days of admission. Two blinded physician investigators adjudicated ARDS by two methods. The investigators directly reviewed all chest radiographs to evaluate for bilateral infiltrates. Several months later, blinded to their previous assessments, they adjudicated ARDS using a standardized rubric to classify radiology reports. A κ statistics was calculated. Regression analyses quantified the association between established risk factors as well as important clinical outcomes and ARDS determined by the aforementioned methods as well as hypoxemia as a surrogate marker.

RESULTS

The κ was 0.47 for the observed agreement between ARDS adjudicated by direct review of chest radiographs and ARDS adjudicated by review of radiology reports. Both the magnitude and direction of bias on the estimates of association between ARDS and established risk factors as well as clinical outcomes varied by method of adjudication.

CONCLUSION

Classification of ARDS by review of dictated radiology reports had only moderate agreement with the current gold standard, ARDS adjudicated by direct review of chest radiographs. While the misclassification of ARDS had varied effects on the estimates of associations with established risk factors, it tended to weaken the association of ARDS with important clinical outcomes. A standardized approach to ARDS adjudication after trauma by direct review of chest radiographs will minimize misclassification bias in future observational studies.

LEVEL OF EVIDENCE

Diagnostic study, level II.

Benefits of Initial Limited Crystalloid Resuscitation in Severely Injured Trauma Patients at Emergency Department

Background

Whether initial limited crystalloid resuscitation (LCR) benefits to all severely injured trauma patients receiving blood transfusions at emergency department (ED) is uncertain. We aimed to determine the role of LCR and its associations with packed red blood cell (PRBC) transfusion during initial resuscitation.

Methods

Trauma patients receiving blood transfusions were reviewed from 2004 to 2013. Patients with LCR (L group, defined as < 2,000 mL) and excessive crystalloid resuscitation (E group, defined as ≥ 2,000 mL) were compared separately in terms of basic demographic, clinical variables, and hospital outcomes. Logistic regression, R-square (R²), and Spearman rho correlation were used for analysis.

Results

A total of 633 patients were included. The mortality was 51% in L group and 45% in E group (P = 0.11). No statistically significant difference was found in terms of basic demographics, vital signs upon arrival at ED, or injury severity between the groups. The volume of blood transfused strongly correlated with the volume of crystalloid infused in E group (R² = 0.955). Crystalloid to PRBC (C/PRBC) ratio was 0.8 in L group and 1.3 in E group (P < 0.01). The correlations between C/PRBC and ED versus ICU versus hospital length of stay (LOS) via Spearman rho were 0.25, 0.22, and 0.22, respectively.

Conclusions

Similar outcomes were observed in trauma patients receiving blood transfusions regardless of the crystalloid infusion volume. More crystalloid infusions were associated with more blood transfusions. The C/PRBC did not demonstrate predictive value regarding mortality but might predict LOS in severely injured trauma patients.

The impact of increased plasma ratios in massively transfused trauma patients: a prospective analysis

PURPOSE

Transfusion ratios approaching 1:1 FFP:PRBC for trauma resuscitation have become the de facto standard of care. The aim of this study was to prospectively evaluate the effect of increasing ratios of FFP:PRBC transfusion on survival for massively transfused civilian trauma patients as well as determine if time to reach the target ratio had any effect on outcomes.

METHODS

This is a prospective, observational study of all trauma patients requiring a massive transfusion (≥10 PRBC in ≤24 h) at a level 1 trauma center over a 2.5-year period. The ratio of FFP:PRBC was tracked hourly up to 24 h post-initiation of massive transfusion. A logistic regression model was utilized to identify the ideal ratio associated with mortality prediction. A stepwise logistic regression was performed to identify independent predictors of mortality.

RESULTS

The study population was predominantly male (89 %) with a mean age of 34.8 ± 16. On admission, 22 % had a systolic blood pressure ≤90 mmHg, 47 % had a heart rate ≥120, and 25 % had a GCS ≤8. The overall mortality was 33 %. The ratio of FFP:PRBC ≥ 1:1.5 was the second most important independent predictor of mortality for this population (R (2) = 0.59). Survivors had a higher FFP:PRBC ratio at all times during the first 24 h of resuscitation.

CONCLUSIONS

Achieving a ratio of FFP:PRBC ≥ 1:1.5 after the initial 24 h of resuscitation significantly improves survival in massively transfused trauma patients compared to patients that achieved a ratio <1:1.5.

Differences in degree, differences in kind: characterizing lung injury in trauma

BACKGROUND

Acute lung injury following trauma remains a significant source of morbidity and mortality. Although multiple trauma studies have used hypoxemia without radiographic adjudication as a surrogate for identifying adult respiratory distress syndrome (ARDS) cases, the differences between patients with hypoxemia alone and those with radiographically confirmed ARDS are not well described in the literature. We hypothesized that nonhypoxemic, hypoxemic, and ARDS patients represent distinct groups with unique characteristics and predictors.

METHODS

Laboratory, demographic, clinical, and outcomes data were prospectively collected from 621 intubated, critically injured patients at an urban Level 1 trauma center from 2005 to 2013. Hypoxemia was defined as PaO2/FIO2 ratio of 300 or lower. ARDS was adjudicated using Berlin criteria, with blinded two-physician consensus review of chest radiographs. Group comparisons were performed by hypoxemia and ARDS status. Logistic regression analyses were performed to separately assess predictors of hypoxemia and ARDS.

RESULTS

Of the 621 intubated patients, 64% developed hypoxemia; 46% of these hypoxemic patients developed ARDS by chest radiograph. Across the three groups (no hypoxemia, hypoxemia, ARDS), there were no significant differences in age, sex, or comorbidities. However, there was an increase in severity of shock, injury, and chest injury by group, with corresponding trends in transfusion requirements and volume of early fluid administration. Outcomes followed a similar stepwise pattern, with pneumonia, multiorgan failure, length of intensive care unit stay, number of ventilator days, and overall mortality highest in ARDS patients. In multiple logistic regression, early plasma transfusion, delayed crystalloid administration, body mass index, and head and chest injury were independent predictors of hypoxemia, while head and chest injury, early crystalloid infusion, and delayed platelet transfusion were independent predictors of ARDS.

CONCLUSION

Hypoxemia and ARDS exist on a spectrum of respiratory dysfunction following trauma, with increasing injury severity profiles and resuscitation requirements. However, they also represent distinct clinical states with unique predictors, which require directed research approaches and targeted therapeutic strategies.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III.

Transfusion of plasma, platelets, and red blood cells in a 1:1:1 vs a 1:1:2 ratio and mortality in patients with severe trauma: the PROPPR randomized clinical trial

IMPORTANCE

Severely injured patients experiencing hemorrhagic shock often require massive transfusion. Earlier transfusion with higher blood product ratios (plasma, platelets, and red blood cells), defined as damage control resuscitation, has been associated with improved outcomes; however, there have been no large multicenter clinical trials.

OBJECTIVE

To determine the effectiveness and safety of transfusing patients with severe trauma and major bleeding using plasma, platelets, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio.

DESIGN, SETTING, AND PARTICIPANTS

Pragmatic, phase 3, multisite, randomized clinical trial of 680 severely injured patients who arrived at 1 of 12 level I trauma centers in North America directly from the scene and were predicted to require massive transfusion between August 2012 and December 2013.

INTERVENTIONS

Blood product ratios of 1:1:1 (338 patients) vs 1:1:2 (342 patients) during active resuscitation in addition to all local standard-of-care interventions (uncontrolled).

MAIN OUTCOMES AND MEASURES

Primary outcomes were 24-hour and 30-day all-cause mortality. Prespecified ancillary outcomes included time to hemostasis, blood product volumes transfused, complications, incidence of surgical procedures, and functional status.

RESULTS

No significant differences were detected in mortality at 24 hours (12.7% in 1:1:1 group vs 17.0% in 1:1:2 group; difference, -4.2% [95% CI, -9.6% to 1.1%]; P = .12) or at 30 days (22.4% vs 26.1%, respectively; difference, -3.7% [95% CI, -10.2% to 2.7%]; P = .26). Exsanguination, which was the predominant cause of death within the first 24 hours, was significantly decreased in the 1:1:1 group (9.2% vs 14.6% in 1:1:2 group; difference, -5.4% [95% CI, -10.4% to -0.5%]; P = .03). More patients in the 1:1:1 group achieved hemostasis than in the 1:1:2 group (86% vs 78%, respectively; P = .006). Despite the 1:1:1 group receiving more plasma (median of 7 U vs 5 U, P < .001) and platelets (12 U vs 6 U, P < .001) and similar amounts of red blood cells (9 U) over the first 24 hours, no differences between the 2 groups were found for the 23 prespecified complications, including acute respiratory distress syndrome, multiple organ failure, venous thromboembolism, sepsis, and transfusion-related complications.

CONCLUSIONS AND RELEVANCE

Among patients with severe trauma and major bleeding, early administration of plasma, platelets, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio did not result in significant differences in mortality at 24 hours or at 30 days. However, more patients in the 1:1:1 group achieved hemostasis and fewer experienced death due to exsanguination by 24 hours. Even though there was an increased use of plasma and platelets transfused in the 1:1:1 group, no other safety differences were identified between the 2 groups.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01545232.

Thromboelastometry and organ failure in trauma patients: a prospective cohort study

INTRODUCTION

Data on the incidence of a hypercoagulable state in trauma, as measured by thromboelastometry (ROTEM), is limited and the prognostic value of hypercoagulability after trauma on outcome is unclear. We aimed to determine the incidence of hypercoagulability after trauma, and to assess whether early hypercoagulability has prognostic value on the occurrence of multiple organ failure (MOF) and mortality.

METHODS

This was a prospective observational cohort study in trauma patients who met the highest trauma level team activation. Hypercoagulability was defined as a G value of ≥ 11.7 dynes/cm(2) and hypocoagulability as a G value of <5.0 dynes/cm(2). ROTEM was performed on admission and 24 hours later.

RESULTS

A total of 1,010 patients were enrolled and 948 patients were analyzed. Median age was 38 (interquartile range (IQR) 26 to 53), 77% were male and median injury severity score was 13 (IQR 8 to 25). On admission, 7% of the patients were hypercoagulable and 8% were hypocoagulable. Altogether, 10% of patients showed hypercoagulability within the first 24 hours of trauma. Hypocoagulability, but not hypercoagulability, was associated with higher sequential organ failure assessment scores, indicating more severe MOF. Mortality in patients with hypercoagulability was 0%, compared to 7% in normocoagulable and 24% in hypocoagulable patients (P <0.001). EXTEM CT, alpha and G were predictors for occurrence of MOF and mortality.

CONCLUSIONS

The incidence of a hypercoagulable state after trauma is 10% up to 24 hours after admission, which is broadly comparable to the rate of hypocoagulability. Further work in larger studies should define the clinical consequences of identifying hypercoagulability and a possible role for very early, targeted use of anticoagulants.

Inflammatory response to trauma: implications for coagulation and resuscitation

PURPOSE OF REVIEW

Recent studies have changed our understanding of the timing and interactions of the inflammatory processes and coagulation cascade following severe trauma. This review highlights this information and correlates its impact on the current clinical approach for fluid resuscitation and treatment of coagulopathy for trauma patients.

RECENT FINDINGS

Severe trauma is associated with a failure of multiple biologic emergency response systems that includes imbalanced inflammatory response, acute coagulopathy of trauma, and endovascular glycocalyx degradation with microcirculatory compromise. These abnormalities are all interlinked and related. Recent observations show that after severe trauma: proinflammatory and anti-inflammatory responses are concomitant, not sequential and resolution of the inflammatory response is an active process, not a passive one. Understanding these interrelated processes is considered extremely important for the development of future therapies for severe trauma in humans.

SUMMARY

Traumatic injuries continue to be a significant cause of mortality worldwide. Recent advances in understanding the mechanisms of end-organ failure, and modulation of the inflammatory response has important clinical implications regarding fluid resuscitation and treatment of coagulopathy.

Medical aspects of terrorist bombings - a focus on DCS and DCR

Although terrorist bombings have tormented the world for a long time, currently they have reached unprecedented levels and become a continuous threat without borders, race or age. Almost all of them are caused by improvised explosive devices. The unpredictability of the terrorist bombings, leading to simultaneous generation of a large number of casualties and severe "multidimensional" blast trauma require a constant vigilance and preparedness of every hospital worldwide. Approximately 1-2.6% of all trauma patients and 7% of the combat casualties require a massive blood transfusion. Coagulopathy is presented in 65% of them with mortality exceeding 50%. Damage control resuscitation is a novel approach, developed in the military practice for treatment of this subgroup of trauma patients. The comparison with the conventional approach revealed mortality reduction with 40-74%, lower frequency of abdominal compartment syndrome (8% vs. 16%), sepsis (9% vs. 20%), multiorgan failure (16% vs. 37%) and a significant reduction of resuscitation volumes, both crystalloids and blood products. DCS and DCR are promising new approaches, contributing for the mortality reduction among the most severely wounded patients. Despite the lack of consensus about the optimal ratio of the blood products and the possible influence of the survival bias, we think that DCR carries survival benefit and recommend it in trauma patients with exsanguinating bleeding.