Bradykinin release following trauma and hemorrhagic shock causes pulmonary alveolar leak in a rodent model

BACKGROUND

Hemorrhage accounts for 40% of the preventable death following severe injury. Activation of systemic coagulation produces bradykinin (BK), which may cause leak from the plasma to the extravascular space and to the tissues, which is part of the complex pathophysiology of trauma-induced end-organ injury. We hypothesize that BK, released during activation of coagulation in severe injury, induces pulmonary alveolar leak.

METHODS

Isolated neutrophils (PMNs) were pretreated with a specific BK receptor B2 antagonist HOE-140/icatibant and BK priming of the PMN oxidase was completed. Rats underwent tissue injury/hemorrhagic shock (TI/HS), TI/icatibant/HS, and controls (no injury). Evans blue dye was instilled, and the percentage leak from the plasma to the lung was calculated from the bronchoalveolar lavage fluid (BALF). CINC-1 and total protein were measured in the BALF, and myeloperoxidase was quantified in lung tissue.

RESULTS

The BK receptor B2 antagonist HOE140/icatibant inhibited (85.0 ± 5.3%) BK priming of the PMN oxidase ( p < 0.05). The TI/HS model caused activation of coagulation by increasing plasma thrombin-antithrombin complexes ( p < 0.05). Versus controls, the TI/HS rats had significant pulmonary alveolar leak: 1.46 ± 0.21% versus 0.36 ± 0.10% ( p = 0.001) and increased total protein and CINC-1 in the BALF ( p < 0.05). Icatibant given after the TI significantly inhibited lung leak and the increase in CINC-1 in the BALF from TI/icatibant/HS rats versus TI/HS ( p < 0.002 and p < 0.05) but not the total protein. There was no PMN sequestration in the lungs. Conclusions: This mixed injury model caused systemic activation of hemostasis and pulmonary alveolar leak likely due to BK release.

CONCLUSION

This mixed injury model caused systemic activation of hemostasis and pulmonary alveolar leak likely due to BK release.

LEVEL OF EVIDENCE

Original Article, Basic Science.

A pilot study of the metabolic profiles of apheresis platelets modified by donor age and sex and in vitro short-term incubation with sex hormones

BACKGROUND

Platelets are part of innate immunity and comprise the cellular portion of hemostasis. Platelets express sex hormone receptors on their plasma membrane and sex hormones can alter their function in vitro. Little is known about how age and sex may affect platelet biology; thus, we hypothesized that platelets from males and females have different metabolomic profiles, which may be altered by age and in vitro treatment with sex hormones.

METHODS

Day 1 apheresis platelets were drawn from five 18-53-year-old, premenopausal younger females (YF), five ≥54-year-old, postmenopausal, older females (OF), five 18-44-year-old younger males (YM), and four ≥45-year-old older males (OM). Platelets were normalized to a standard concentration and metabolomics analyses were completed. Unsupervised statistical analyses and hierarchical clustering with principal component analyses were completed.

RESULTS

Platelets from OM had (1) elevated mono-, di- and tri-carboxylates, (2) increased levels of free fatty acids, acyl-carnitines, and free amino acids, and (3) increased purine breakdown and deamination products. In vitro incubation with sex hormones only affected platelets from OM donors with trends towards increased ATP and other high-energy purines and decreases in L-proline and other amino acids.

CONCLUSION

Platelets from OM's versus YF, OF, and YM have a different metabolome implying increased energy metabolism, more free fatty acids, acylcarnitines, and amino acids, and increased breakdown of purines and deamination products. However, only platelets from OM were affected by sex hormones in vitro. Platelets from OM are metabolically distinct, which may impart functional differences when transfused.

BLOOD TYPE O IS A RISK FACTOR FOR HYPERFIBRINOLYSIS AND MASSIVE TRANSFUSION AFTER SEVERE INJURY

ABSTRACT

Background: Blood type O is the most common blood type and has lower von Willebrand factor (vWF) levels (25%-35% lower than non-O blood types). von Willebrand factor is important for initiating platelet attachment and binding factor VIII. We hypothesized that patients with type O blood are at an increased risk of trauma-induced coagulopathy and bleeding post injury. Study Design: Adult trauma activations with known blood type at a level I trauma center with field systolic blood pressure < 90 mm Hg were studied retrospectively. The relationships of blood group O versus non-O to coagulation assays, massive transfusion (MT), ventilator-free days, and mortality were adjusted for confounders. Hyperfibrinolysis (HF) was defined as thromboelastogram of percent lysis in 30 min > 3%, and fibrinolysis shutdown was defined as percent lysis in 30 min < 0.9%. von Willebrand factor activity was quantified on 212 injured patients using a STAGO apparatus. Results: Overall, 268 patients met criteria. Type O patients were more likely to develop HF than non-type O blood patients (43% vs. 29%, P = 0.06) and had significantly lower vWF activity (222% vs. 249%, P = 0.01). After adjustment for New Injury Severity Score and blunt mechanism, type O had higher odds of HF (odds ratio, 1.94, 95% confidence interval, 1.09-3.47) and increased odds of MT (odds ratio, 3.02; 95% confidence interval, 1.22-7.49). Other outcomes were not significantly affected. Conclusion: Type O patients with hypotension had increased HF and MT post injury, and these were associated with lower vWF activity. These findings have implications for the monitoring of HF in patients receiving type O whole-blood transfusions post injury.

SHOCK INDUCES ENDOTHELIAL PERMEABILITY AFTER TRAUMA THROUGH INCREASED ACTIVATION OF RHOA GTPASE

ABSTRACT

Introduction: Severely injured patients develop a dysregulated inflammatory state characterized by vascular endothelial permeability, which contributes to multiple organ failure. To date, however, the mediators of and mechanisms for this permeability are not well established. Endothelial permeability in other inflammatory states such as sepsis is driven primarily by overactivation of the RhoA GTPase. We hypothesized that tissue injury and shock drive endothelial permeability after trauma by increased RhoA activation leading to break down of endothelial tight and adherens junctions. Methods: Human umbilical vein endothelial cells (HUVECs) were grown to confluence, whereas continuous resistance was measured using electrical cell-substrate impedance sensing (ECIS) Z-Theta technology, 10% ex vivo plasma from severely injured trauma patients was added, and resistance measurements continued for 2 hours. Areas under the curve (AUCs) were calculated from resistance curves. For GTPase activity analysis, HUVECs were grown to confluence and incubated with 10% trauma plasma for 5 minutes before harvesting of cell lysates. Rho and Rac activity were determined using a G-LISA assay. Significance was determined using Mann-Whitney tests or Kruskal-Wallis test, and Spearman ρ was calculated for correlations. Results: Plasma from severely injured patients induces endothelial permeability with plasma from patients with both severe injury and shock contributing most to this increased permeability. Surprisingly, Injury Severity Score (ISS) does not correlate with in vitro trauma-induced permeability (-0.05, P > 0.05), whereas base excess (BE) does correlate with permeability (-0.47, P = 0.0001). The combined impact of shock and injury resulted in a significantly smaller AUC in the injury + shock group (ISS > 15, BE < -9) compared with the injury only (ISS > 15, BE > -9; P = 0.04) or minimally injured (ISS < 15, BE > -9; P = 0.005) groups. In addition, incubation with injury + shock plasma resulted in higher RhoA activation ( P = 0.002) and a trend toward decreased Rac1 activation ( P = 0.07) compared with minimally injured control. Conclusions: Over the past decade, improved early survival in patients with severe trauma and hemorrhagic shock has led to a renewed focus on the endotheliopathy of trauma. This study presents the largest study to date measuring endothelial permeability in vitro using plasma collected from patients after traumatic injury. Here, we demonstrate that plasma from patients who develop shock after severe traumatic injury induces endothelial permeability and increased RhoA activation in vitro . Our ECIS model of trauma-induced permeability using ex vivo plasma has potential as a high throughput screening tool to phenotype endothelial dysfunction, study mediators of trauma-induced permeability, and screen potential interventions.

Hormones, age, and sex affect platelet responsiveness in vitro

BACKGROUND

Female sex confers a survival advantage following severe injury in the setting of trauma-induced coagulopathy, with female platelets having heightened responsiveness likely due to estrogen. The effects of testosterone on platelet biology are unknown, and platelets express both estradiol and androgen receptors on the plasma membrane. We hypothesize testosterone decreases platelet responses in vitro, and there are baseline differences in platelet function and metabolism stratified by sex/age.

STUDY DESIGN AND METHODS

Apheresis platelets were collected from: older males (OM) ≥45 years, younger males (YM) <45 years, older females (OF) ≥54 years, and younger females (YF) <54 years, and testosterone and estradiol were measured. Platelets were incubated with testosterone (5.31 ng/ml), estradiol (105 pg/ml) or vehicle and stimulated with buffer, adenosine diphosphate (20 μM), platelet activating factor (2 μM), or thrombin (0.3 U/ml). Aggregation, CD62P surface expression, fibrinogen receptor surface expression, and platelet mitochondrial metabolism were measured.

RESULTS

Testosterone significantly inhibited aggregation in OF and OM (p < .05), inhibited CD41a expression in YF, YM, and OM (p < .05), and affected a few of the baseline amounts of CD62P surface expression but not platelet activation to platelet-activating factor and adenosine diphosphate, and variably changed platelet metabolism.

DISCUSSION

Platelets have sex- and age-specific aggregation, receptor expression, and metabolism. Testosterone decreases platelet function dependent on the stimulus, age, and sex. Similarly, platelet metabolism has varying responses to sex hormones with baseline metabolic differences dependent upon sex and age.

The α-globin chain of hemoglobin potentiates tissue plasminogen activator induced hyperfibrinolysis in vitro

BACKGROUND

Severe injury predisposes patients to trauma-induced coagulopathy, which may be subdivided by the state of fibrinolysis. Systemic hyperfibrinolysis (HF) occurs in approximately 25% of these patients with mortality as high as 70%. Severe injury also causes the release of numerous intracellular proteins, which may affect coagulation, one of which is hemoglobin, and hemoglobin substitutes induce HF in vitro. We hypothesize that the α-globin chain of hemoglobin potentiates HF in vitro by augmenting plasmin activity.

METHODS

Proteomic analysis was completed on a pilot study of 30 injured patients before blood component resuscitation, stratified by their state of fibrinolysis, plus 10 healthy controls. Different concentrations of intact hemoglobin A, the α- and β-globin chains, or normal saline (controls) were added to whole blood, and tissue plasminogen activator (tPA)-challenged thrombelastography was used to assess the degree of fibrinolysis. Interactions with plasminogen (PLG) were evaluated using surface plasmon resonance. Tissue plasminogen activator-induced plasmin activity was evaluated in the presence of the α-globin chain.

RESULTS

Only the α- and β-globin chains increased in HF patients (p < 0.01). The α-globin chain but not hemoglobin A or the β-globin chain decreased the reaction time and significantly increased lysis time 30 on citrated native thrombelastographies (p < 0.05). The PLG and α-globin chain had interaction kinetics similar to tPA:PLG, and the α-globin chain increased tPA-induced plasmin activity.

CONCLUSIONS

The α-globin chain caused HF in vitro by binding to PLG and augmenting plasmin activity and may represent a circulating "moonlighting" mediator released by the tissue damage and hemorrhagic shock inherent to severe injury.

LEVEL OF EVIDENCE

Prognostic, level III.

Strategies for successful implementation of resuscitative endovascular balloon occlusion of the aorta in an urban Level I trauma center

BACKGROUND

The rationale for resuscitative endovascular balloon occlusion of the aorta (REBOA) is to control life-threatening subdiaphragmatic bleeding and facilitate resuscitation; however, incorporating this into the resuscitative practices of a trauma service remains challenging. The objective of this study is to describe the process of successful implementation of REBOA use in an academic urban Level I trauma center. All REBOA procedures from April 2014 through December 2019 were evaluated; REBOA was implemented after surgical faculty attended a required and internally developed Advanced Endovascular Strategies for Trauma Surgeons course. Success was defined by sustained early adoption rates.

METHODS

An institutional protocol was published, and a REBOA supply cart was placed in the emergency department with posters attached to depict technical and procedural details. A focused professional practice evaluation was utilized for the first three REBOA procedures performed by each faculty member, leading to internal privileging.

RESULTS

Resuscitative endovascular balloon occlusion of the aorta was performed in 97 patients by nine trauma surgeons, which is 1% of the total trauma admissions during this time. Each surgeon performed a median of 12 REBOAs (interquartile range, 5-14). Blunt (77/97, 81%) or penetrating abdominopelvic injuries (15/97, 15%) comprised the main injury mechanisms; 4% were placed for other reasons (4/97), including ruptured abdominal aortic aneurysms (n = 3) and preoperatively for a surgical oncologic resection (n = 1). Overall survival was 65% (63/97) with a steady early adoption trend that resulted in participation in a Department of Defense multicenter trial.

CONCLUSION

Strategies for how departments adopt new procedures require clinical guidelines, a training program focused on competence, and a hospital education and privileging process for those acquiring new skills.

LEVEL OF EVIDENCE

Therapeutic, level V.

Atypical May-Thurner syndrome caused by endovascular aortic aneurysm repair

May-Thurner syndrome is characterized by unilateral lower extremity venous hypertension and stasis due to compression of an iliac vein between an iliac artery and the lumbar spine. In almost all cases, the left common iliac vein is compressed by the right common iliac artery; however, other patterns have been described. Rarely, May-Thurner syndrome may be created iatrogenically as a result of iliac artery stenting. We present an unusual case of new left common iliac vein thrombosis caused by ipsilateral left iliac artery compression after aortobi-iliac endovascular aneurysm repair.

Epidemiology of Wire-Bristle Grill Brush Injury in the United States, 2002-2014

Objectives

The purpose of this study was to investigate the epidemiology of wire-bristle grill brush injury.

Study Design and Setting

Cross-sectional analysis of national databases; literature review.

Subjects and Methods

The Consumer Product Safety Commission’s National Electronic Injury Surveillance System (NEISS) was used to derive a national weighted estimate of emergency department visits for wire bristle injury from 2002 to 2014. Date, location of injury, demographics, and outcomes were analyzed. A literature search and a consumer-reported injury database ( SaferProducts.gov ) were interrogated to provide ancillary sources of data.

Results

A total of 43 cases were found within the NEISS database, which extrapolated to an estimated 1698 (95% confidence interval, 1468-1927) emergency department visits nationwide. In the NEISS database, the mean age was 30 years, and the sex distribution of the patients was similar (21 males vs 22 females). The most common location of injury was the oropharynx in both the NEISS database (23 of 43, 53.4%) and the literature review (11 of 36, 30.5%). However, the oral cavity was the most frequent site in the consumer-reported SaferProducts.gov database (9 of 24, 37.5%). The majority of patients in the NEISS were treated in the emergency department (31 of 43, 69.7%). Raw case counts were highest in June, July, and August, with the highest number of events in the month of July.

Conclusion

Injury from wire-bristle grill brush is uncommon but prevalent during certain seasons. Otolaryngologists play an important in the diagnosis and treatment of these injuries. Awareness among consumers and product manufacturers is necessary to promote safety.