Role of the coagulation system in ARDS

Venous Thromboembolism in COVID-19 Patients: A Single-Center Case Series

: Since thrombosis occurrence among coronavirus disease 2019 (COVID-19) patients is a critical complication, this study aimed to describe the clinical characteristics and outcomes of COVID-19-associated pulmonary thromboembolism (PTE). This case series of 39 venous thromboembolism (VTE) patients represents clinical characteristics, laboratory data, imaging data, and outcomes. The mean age of the patients was 55 ± 15 years. Moreover, 25 patients (64.10%) were male. The most frequent COVID-19 clinical presentations were dyspnea and cough in 22 (56.41%) and 19 (48.71%) patients, respectively. Additionally, the most frequent PTE clinical presentations were palpitation and anxiety in 28 (71.79%) and dyspnea in 24 (61.53%) patients. Additionally, eight patients (20.51%) showed deep vein thrombosis in color Doppler ultrasound. The mean measures of D-dimer, erythrocyte sedimentation rate and C-reactive protein were 3680 ng/mL, 53 mm/hour, and 44 mg/L, respectively. Supplemental oxygen and a ventilator were required in 29 (74.35%) and 2 (5.12%) patients, respectively. One patient died from PTE complications, and others improved without any complications. The VTE is a potentially life-threatening complication that frequently occurs in patients with COVID-19. Therapeutic doses of anticoagulants, extended thromboprophylaxis, meticulous assessments, follow-up, and high clinical suspicion to the early detection of PTE are necessary in this regard.

Prediction of Acute Respiratory Distress Syndrome in Traumatic Brain Injury Patients Based on Machine Learning Algorithms

Background: Acute respiratory distress syndrome (ARDS) commonly develops in traumatic brain injury (TBI) patients and is a risk factor for poor prognosis. We designed this study to evaluate the performance of several machine learning algorithms for predicting ARDS in TBI patients. Methods: TBI patients from the Medical Information Mart for Intensive Care-III (MIMIC-III) database were eligible for this study. ARDS was identified according to the Berlin definition. Included TBI patients were divided into the training cohort and the validation cohort with a ratio of 7:3. Several machine learning algorithms were utilized to develop predictive models with five-fold cross validation for ARDS including extreme gradient boosting, light gradient boosting machine, Random Forest, adaptive boosting, complement naïve Bayes, and support vector machine. The performance of machine learning algorithms were evaluated by the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, accuracy and F score. Results: 649 TBI patients from the MIMIC-III database were included with an ARDS incidence of 49.5%. The random forest performed the best in predicting ARDS in the training cohort with an AUC of 1.000. The XGBoost and AdaBoost ranked the second and the third with an AUC of 0.989 and 0.815 in the training cohort. The random forest still performed the best in predicting ARDS in the validation cohort with an AUC of 0.652. AdaBoost and XGBoost ranked the second and the third with an AUC of 0.631 and 0.620 in the validation cohort. Several mutual top features in the random forest and AdaBoost were discovered including age, initial systolic blood pressure and heart rate, Abbreviated Injury Score chest, white blood cells, platelets, and international normalized ratio. Conclusions: The random forest and AdaBoost based models have stable and good performance for predicting ARDS in TBI patients. These models could help clinicians to evaluate the risk of ARDS in early stages after TBI and consequently adjust treatment decisions.

Specific cytokines in the inflammatory cytokine storm of patients with COVID-19-associated acute respiratory distress syndrome and extrapulmonary multiple-organ dysfunction

BACKGROUND

To date, specific cytokines associated with development of acute respiratory distress syndrome (ARDS) and extrapulmonary multiple organ dysfunction (MOD) in COVID-19 patients have not been systematically described. We determined the levels of inflammatory cytokines in patients with COVID-19 and their relationships with ARDS and extrapulmonary MOD.

METHODS

The clinical and laboratory data of 94 COVID-19 patients with and without ARDS were analyzed. The levels of inflammatory cytokines (interleukin 6 [IL-6], IL-8, IL-10, and tumor necrosis factor α [TNF-α]) were measured on days 1, 3, and 5 following admission. Seventeen healthy volunteers were recruited as controls. Correlations in the levels of inflammatory cytokines with clinical and laboratory variables were analyzed, furthermore, we also explored the relationships of different cytokines with ARDS and extrapulmonary MOD.

RESULTS

The ARDS group had higher serum levels of all 4 inflammatory cytokines than the controls, and these levels steadily increased after admission. The ARDS group also had higher levels of IL-6, IL-8, and IL-10 than the non-ARDS group, and the levels of these cytokines correlated significantly with coagulation parameters and disseminated intravascular coagulation (DIC). The levels of IL-6 and TNF-α correlated with the levels of creatinine and urea nitrogen, and were also higher in ARDS patients with acute kidney injury (AKI). All 4 inflammatory cytokines had negative correlations with PaO₂/FiO₂. IL-6, IL-8, and TNF-α had positive correlations with the APACHE-II score. Relative to survivors, non-survivors had higher levels of IL-6 and IL-10 at admission, and increasing levels over time.

CONCLUSIONS

The cytokine storm apparently contributed to the development of ARDS and extrapulmonary MOD in COVID-19 patients. The levels of IL-6, IL-8, and IL-10 correlated with DIC, and the levels of IL-6 and TNF-α were associated with AKI. Relative to survivors, patients who died within 28 days had increased levels of IL-6 and IL-10.

The significance of disseminated intravascular coagulation on multiple organ dysfunction during the early stage of acute respiratory distress syndrome

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is a predominant cause of death in acute respiratory distress syndrome (ARDS). Disseminated intravascular coagulation (DIC) is recognized as a syndrome that frequently develops MODS. To test the hypothesis that DIC scores are useful for predicting MODS development and that DIC is associated with MODS, we retrospectively analyzed the data of a prospective, multicenter study on ARDS.

METHODS

Patients who met the Berlin definition of ARDS were included. DIC scores as well as the disease severity and the development of MODS on the day of the diagnosis of ARDS (day 0) and day 3 were evaluated. The primary and secondary outcomes were the development of MODS and the hospital mortality.

RESULTS

In the 129 eligible patients, the prevalence of DIC was 45.7% (59/129). DIC patients were more seriously ill and exhibited a higher prevalence of MODS on days 0 and 3 than non-DIC patients. The DIC scores on day 0 detected the development of MODS with good area under the receiver operating characteristic curve (0.714, p<.001). DIC on day 0 was significantly associated with MODS on days 0 and 3 (odds ratio 1.53 and 1.34, respectively). Patients with persistent DIC from days 0 to 3 had higher rates of both MODS on day 3 (p=.035) and hospital mortality (p=.031) than the other patients.

CONCLUSIONS

DIC scores were able to predict MODS, and DIC was associated with MODS during the early stage of ARDS. Persistent DIC may also have role in this association.

Spectrum of Diseases/conditions Exhibiting Hemostatic Abnormalities in Patients Admitted to a Medical Intensive Care Unit of a Tertiary Care Hospital

Background and Aims:

In a medical intensive care unit (MICU), many patients develop hemostatic abnormalities, ranging from abnormal clotting tests to frank bleeding. The aim of this study was to assess the etiology of diseases that present with bleeding, its common bleeding manifestations, incidence, MICU stay, mortality, and transfusion requirements in an Indian setup and also to assess if the Acute Physiology and Chronic Health Evaluation II (APACHE II) score can be used as a predictor for blood transfusion requirements.

Materials and Methods:

Between July 2013 and August 2014, 200 patients with clinically significant bleeding admitted in the MICU were prospectively evaluated. Detailed history, examination, laboratory investigations, APACHE II score, and requirement of blood products were also noted. The endpoints were discharge or death.

Results:

The spectrum of diseases that presented with bleeding was 47 patients with malaria (23.5%) followed by 36 acute undifferentiated febrile illness (18.0%), 33 dengue (16.5%), 30 leptospirosis (15.0%), 31 acute fulminant hepatitis (15.5%), 14 sepsis (7.0%), and the rest nine miscellaneous causes. The most common bleeding manifestation observed was hematuria in 62/200 (31%). Among the patients studied, 126 expired (63%) and 74 survived (37%). Of the 200 patients, 48/200 (24%) received packed cells, 78/200 (39%) fresh frozen plasma, and 82/200 (41%) platelets.

Conclusions:

Tropical diseases formed the majority of admissions with bleeding manifestations. Thrombocytopenia is an important marker to predict mortality and also has a significant association with MICU stay. APACHE II score was found to be a good predictor of blood transfusion requirements.

Dexamethasone Preconditioning in Cardiac Procedures Reduces Decreased Antithrombin Activity and Is Associated to Beneficial Outcomes: Role of Endothelium

Introduction: Decreased antithrombin (AT) activity in patients scheduled for cardiovascular surgery under cardiopulmonary bypass (CPB) is related to increased postoperative complications and hospitalization time. Indirect evidence suggests that glucocorticoids mitigate this decreased AT activity. To better understand the beneficial effects of AT we have analyzed: (i) the clinical relevance of acute dexamethasone (DX) administration before cardiac surgery on AT activity, (ii) the modulation by DX of AT expression in human endothelial cells (hECs), (iii) the activity of AT on migration and angiogenesis of hECs, or on angiogenesis of rat aorta. Methods: A retrospective cohort study in patients undergoing aortic valve replacement surgery was designed to evaluate the effect of DX administration on AT activity at five separate time points: preoperatively, during CPB, at intensive care unit admission and at 12 and 24 h post-intervention. We have analyzed also clinical differences in postoperative outcomes as safety and the length of stay in hospitalization. Changes in mRNA levels of AT induced by DX were determined by qRT-PCR in human coronary (hCEC), aorta (hAEC) and cardiac microvasculature (hCMEC) endothelial cells. AT activity on migration and angiogenesis were also assayed. Angiogenic growth of rat aortic rings incubated in Matrigel® was determined in presence and absence of AT. Results: The cohort comprised 51 patients in the control group and 29 patients in the group receiving dexamethasone. Preoperative DX supplementation reduced intraoperative decrease of AT activity (67.71 ± 10.49% DX treated vs. 58.12 ± 9.11% untreated, p < 0.001) that could be related to a decrease in the hospitalization time (7.59 ± 4.08 days DX treated vs. 13.59 ± 16.00 days untreated, p = 0.014). Treatment of hECs with 500 nM DX slightly increased AT expression. Incubation with 0.5 and 1 IU/mL of AT increased migration and angiogenesis in hCAECs and hAECs, but not in hCMECs. The same concentrations of AT potentiated angiogenic sprouting of new vessels from rat aorta. Conclusion: Preoperative DX supplementation could be an interesting procedure to avoid excessive decrease in AT levels during cardiac surgery. Positive outcomes associated with maintaining adequate AT levels could be related to its potential beneficial effect on endothelial function (migration and angiogenesis).

Activated protein C attenuates acute lung injury and apoptosis in a hyperoxic animal model

Evidence suggests that activated protein C (APC) attenuates acute lung injury (ALI) through antithrombotic and anti-inflammatory mechanisms. The aim of this study was to determine the effects of APC on ALI in adult rats exposed to hyperoxic environment. Rats were divided into control, hyperoxia, hyperoxia + APC, and APC. Hyperoxia and hyperoxia + APC were exposed to 1, 3, and 5 days of hyperoxia. Hyperoxia + APC and APC were injected with APC (5 mg/kg, i.p.) every 12 h. Control and hyperoxia received isotonic sodium chloride solution injection. Measurement of wet to dry ratio and albumin leak demonstrated significant improvement in hyperoxia + APC when compared with hyperoxia. Apoptosis, as measured by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, was significantly reduced in hyperoxia + APC when compared with hyperoxia. Histological evaluation of lung sections showed significant reduction in inflammation, edema, and in the number of marginating neutrophils in hyperoxia + APC as compared with hyperoxia. Transcriptional expression of lung inflammatory mediators demonstrated a time-dependent surge in the levels TNF-alpha, IL-1beta, and IL-6 in response to hyperoxia that was attenuated with APC administration in the presence of hyperoxia. In this rat model, APC attenuates lung injury and the expression of inflammatory mediators in ALI secondary to hyperoxia.

Plasminogen Activator Inhibitor I 4G/5G Polymorphism in Neonatal Respiratory Distress Syndrome

Fibrin monomers inhibit surfactant function. 4G/5G insertion/deletion polymorphism plays an important role in the regulation of plasminogen activator inhibitor 1 (PAI-1) gene expression. To examine the genotype distribution of PAI-1 polymorphism in 60 infants with respiratory distress syndrome (RDS) and 53 controls, an allele-specific polymerase chain reaction (PCR) was used. The proportion of 4G/4G, 4G/5G, and 5G/5G genotypes did not differ statistically between the RDS and control groups (P > .05). Having PAI-1 4G/4G genotype polymorphism appears to increase the risk of RDS (odds ratio [OR] =1.5; 95% confidence interval [CI], 0.5-4.3), although it was not statistically significant. No relation was found between the PAI-1 4G/5G polymorphisms and RDS, but there was an increased risk associated with the 4G variant of the PAI-1 gene. We believe that our findings of increased 4G allele of the PAI-1 gene in infants with RDS would also help to clarify the pathogenesis of RDS.

Gabexate mesilate inhibits the expression of HMGB1 in lipopolysaccharide-induced acute lung injury

High mobility group box 1 (HMGB1) is an important late mediator of acute lung injury. Gabexate mesilate (GM) is a synthetic protease inhibitor with some anti-inflammatory action. We aimed to evaluate the effect of GM on HMGB1 in lipopolysaccharide (LPS)-induced lung injury in rats. Prior to the injection of LPS to induce lung injury, rats were administered saline or GM. Injury to the lung and expression of HMGB1, plasminogen activator inhibitor-1 (PAI-1), and protease-activated receptor-2 (PAR-2) were examined. In an accompanying in vitro study, we performed LPS stimulation under GM administration in a mouse macrophage cell line and measured the quantity of HMGB1 and cytokines in the supernatant, and cell signal in the cells. Histologic examination revealed that interstitial edema, leukocytic infiltration, and HMGB1 protein expression were markedly reduced in the GM+LPS group compared wih the LPS group. Furthermore, LPS-induced increases in PAI-1 and PAR-2 activity and in plasma HMGB1 concentrations were lower in the rats given both GM and LPS than in the rats given LPS alone. Release of HMGB1 and cytokines from the cell after the administration of LPS were decreased by GM. Phosphorylation of IκB was inhibited by GM. GM may have inhibited PAI-1 and PAR-2, thereby indirectly inhibiting HMGB1 and reducing tissue damage in the lung. This indicates that GM can inhibit lung injury induced by LPS in rats. GM is a candidate for use in novel strategies to prevent or minimize lung injury in sepsis.

A review of pulmonary coagulopathy in acute lung injury, acute respiratory distress syndrome and pneumonia

Enhanced bronchoalveolar coagulation is a hallmark of many acute inflammatory lung diseases such as acute lung injury, acute respiratory distress syndrome and pneumonia. Intervention with natural anticoagulants in these diseases has therefore become a topic of interest. Recently, new data on the role of pulmonary coagulation and inflammation has become available. The aim of this review is to summarize these findings. Furthermore, the results of anticoagulant therapeutic interventions in these disorders are discussed.

Effect of covalent antithrombin-heparin complex on developmental mechanisms in the lung

We have developed a potent antithrombin (AT)-heparin conjugate (ATH) that is retained in the lung to prevent pulmonary thrombosis associated with respiratory distress in premature newborns. During continuing maturation, pulmonary angiogenesis in premature infants would be a crucial process in lung development. A naturally occurring latent form of antithrombin (L-AT) has antiangiogenic effects on lung vascularization. However, impact of latent ATH (L-ATH) on developing lung vascularization is unknown. Thus, effects of L-AT and L-ATH on fetal murine lung development were compared. Lung buds from embryonic day 11.5 (E11.5) Tie2-LacZ mouse embryos were incubated in DMEM plus FBS supplemented with PBS, AT, L-AT, heparin, ATH, or L-ATH. Vasculature of cultured explants was quantified by X-galactosidase staining. RNA was analyzed with murine gene probes for angiopoietin (Ang)-1, Ang-2, fibroblast growth factor 2 (FGF2), platelet endothelial cell adhesion molecule (PECAM), and vascular endothelial growth factor (VEGF). FGF2-supplemented medium was used to test contribution to effects of L-AT and L-ATH on angiogenesis. Epithelial branching morphogenesis was inhibited by L-AT (P = 0.003) and heparin (P < 0.001). L-AT and heparin decreased relative vascular area compared with PBS, ATH, and L-ATH. Expressions of all genes studied were downregulated by L-AT. However, L-AT and L-ATH inhibited branching morphogenesis and vasculature with added FGF2. These findings indicate that covalent linkage of AT to heparin negates disruptive effects of these moieties on lung morphology, vascularization, and growth factor gene expression. ATH may have enhanced safety as an anticoagulant during vascular development.

Combining early coagulation and inflammatory status improves prediction of mortality in burned and nonburned trauma patients

BACKGROUND

After injury, there is a synergistic response between inflammation and coagulation systems. We hypothesized that combining markers of these processes and standard clinical indices would improve early prediction of in- hospital mortality in burned and nonburned trauma patients.

METHODS

Patients admitted to the surgical or burn intensive care unit within 24 hours of injury with an anticipated stay >or=3 days were enrolled during a one year period. Upon admission, blood was drawn for thromboelastography, plasma-based clotting assays, and cytokine levels. Clinical indices and multiple organ dysfunction syndrome (MODS) scores were recorded. Candidate variables evaluated included age, percentage third degree burns, inhalation injury, percentage total body surface area burns, interleukin-6, tumor necrosis factor alpha, interleukin-8, prothrombin time, partial thromboplastin time (PTT), maximal amplitude reflective of clot strength, group (burn or nonburn) and admission MODS. Multiple logistic regression with stepwise selection and likelihood ratio test was performed to identify predictors for mortality. A receiver operating characteristic (ROC) curve was constructed to assess the diagnostic performance of identified predictors. Validation of the model with an additional cohort was performed.

RESULTS

For model development, we enrolled 25 burned and 33 nonburned trauma patients (20 blunt and 13 penetrating injuries). Fifteen deaths occurred. Multiple logistic regression analysis identified six independent risk factors for death: age, percentage third degree burns, inhalation injury, tumor necrosis factor alpha level, maximal amplitude, and MODS score with an area under ROC curve of 0.961 (95% confidence interval: 0.891, 1.000, p < 0.05). The area under the ROC curve for the validation cohort (n = 66) was 0.936 (95% confidence interval: 0.875, 0.997, p < 0.001).

CONCLUSION

Our model improves prediction of in-hospital mortality in comparison to previous methods for burn and nonburn trauma patients. Furthermore, our model is equally applicable to all patients regardless of type of traumatic injury (nonburn or burn). This improvement is because of the inclusion of patient's early coagulation and inflammatory status in addition to standard clinical indices. These data provide a baseline within which to measure incremental improvements in care.

Femoral nailing-related coagulopathy determined by first-hit magnitude: an animal study

We asked whether coagulopathy worsened during femoral intramedullary nailing in the presence of lung contusion and hemorrhagic shock and whether reamed or unreamed nailing influenced these results. In 30 Merino sheep, we induced hemorrhagic shock and/or standardized lung contusion followed by femoral nailing. Six groups of five each were assigned as follows: thoracotomy control groups treated with reamed or unreamed nailing, lung contusion groups treated with reamed or unreamed nailing, and shock and lung contusion groups treated with reamed or unreamed nailing. After lung contusion alone (first hit), the serum values of antithrombin III, factor V, and fibrinogen were considerably altered after reamed and unreamed femoral nailing (second hit) 4 hours postoperatively. In the lung contusion and shock groups, we found a substantial reduction for all serum coagulative parameters between baseline and fixation after reamed and unreamed nailing. The magnitude of the first hit is increased if hemorrhagic shock is added to a lung contusion determined by hemostatic reactions. The magnitude of the injury appears equally important as the type of subsequent surgery and should be considered in planning for fracture fixation in patients at high risk for complications.

Thrombin activatable fibrinolysis inhibitor activity, thrombin-antithrombin complex and D-dimer levels in preterm neonates with early respiratory distress syndrome

Intraalveolar fibrin deposition found in neonates with respiratory distress syndrome (RDS) is explained by the activation of the coagulation system and inefficient fibrinolysis. However, thrombin activatable fibrinolysis inhibitor activity (TAFIa), an inhibitor of fibrinolysis, and the ratio of D-dimer to thrombin-antithrombin complex (D-dimer/TAT), an index of fibrinolytic activity, have not been reported previously in neonatal RDS. Aim of this study is to evaluate the influence of plasma TAFIa levels on the fibrinolytic state in neonatal RDS. The RDS group (Group 1) consisted of 29 neonates, and 18 neonates served as the control group (Group 2). Plasma TAFIa levels and D-dimer/TAT ratios were evaluated in all neonates in the first 6 hr of life. Neonates in the RDS group were further divided into two subgroups; Group 1a consisted of 12 neonates with evidence of mild asphyxia (Apgar score at 5 min <7 and cord pH <7.26), and Group 1b consisted of 17 nonasphyxiated neonates. No significant difference was found in TAFIa levels and D-dimer/TAT ratios between Groups 1 and 2 [214% (56.2-361%) and 124.3 (4.4-3,921) in Group 1 and 201% (60.3-381%) and 147 (5.9-1,426) in Group 2]. There were negative correlations between cord pH and TAFIa levels in both groups. Increased TAFIa levels and decreased D-dimer/TAT ratios and platelet counts were detected in mildly asphyxiated neonates when compared with nonasphyxiated ones. TAFIa is not responsible for the hypofibrinolytic state reported in RDS. However, asphyxia influences TAFIa levels and increased TAFIa levels depress fibrinolysis.

RETRACTED ARTICLE: Nafamostat mesilate inhibits the expression of HMGB1 in lipopolysaccharide-induced acute lung injury

PURPOSE

High mobility group box 1 (HMGB1) protein has recently been shown to be an important late mediator of acute lung injury and a promising therapeutic target. Nafamostat mesilate (NM) is a broad-range synthetic protease inhibitor with some anti-inflammatory action. The purpose of this study was to evaluate the effect of NM on HMGB1 in lipopolysaccharide (LPS)-induced lung injury in rats.

METHODS

Male Wistar rats were given either saline (LPS group) or NM (NM+LPS group) 30 min before the intravenous injection of a bolus of LPS (5 mg.kg(-1)). After the administration of LPS, injury to the lung and the expression of HMGB1, tumor necrosis factor-alpha (TNF-alpha), and plasminogen activator inhibitor-1 (PAI-1) were examined.

RESULTS

Histological examination revealed that interstitial edema, leukocytic infiltration, and HMGB1 protein expression were markedly reduced in the NM+LPS group compared to the LPS group. Furthermore, the LPS-induced increases in PAI-1 activity and in plasma TNF-alpha concentrations were also lower in the rats given both NM and LPS than in the rats given LPS alone.

CONCLUSIONS

The anticoagulatory activity of NM may have inhibited PAI-1, while its anti-inflammatory activity blockaded TNF-alpha, thereby indirectly inhibiting HMGB1 and reducing tissue damage in the lung. These findings indicate that NM can inhibit the lung injury induced by LPS in rats. NM is an excellent candidate for use in new therapeutic strategies to prevent or minimize lung injury.

Protective effects of nafamostat mesilate on liver injury induced by lipopolysaccharide in rats: possible involvement of CD14 and TLR-4 downregulation on Kupffer cells

Nafamostat mesilate (NM) is a synthetic protease inhibitor with various biological effects. To determine its effect on liver injury related to sepsis, we investigated the effects of NM on lipopolysaccharide (LPS)-induced liver injury. Wistar rats were allocated into two groups; the NM group underwent intraperitoneal NM administration 30 min before LPS administration, and the control group underwent PBS administration. Serum AST and ALT levels were significantly decreased in NM-treated rats. Reduced levels of TNF-alpha, IL-1beta, and IFN-gamma were observed after LPS administration in NM-treated rats. No significant differences were observed in IL-6 levels between the NM and the control group. In contrast, HGF levels were significantly increased only in control rats. NM treatment decreased protein and mRNA levels of TLR-4 and CD14. Our data suggest that NM treatment has protective effects against LPS-induced hepatotoxicity through downregulation of TLR4 and CD14 in liver, which decreased TNF-alpha, IL-1beta, and IFN-gammaproduction in liver.

Coagulopathy in the trauma patient

PURPOSE OF REVIEW

Homeostasis represents a delicate balance between hemostatic and fibrinolytic processes. This balance permits arrest of hemorrhage after mild injury but prevents thrombosis from occurring under normal circumstances. Trauma disturbs the equilibrium between hemostatic and fibrinolytic processes, frequently producing either a hypocoagulable state or a hypercoagulable state depending on the severity of injury, degree of hemorrhage, and the nature of the resuscitation. The purpose of this review is to describe the epidemiology and pathophysiology of coagulopathy after trauma and to discuss novel methods of treating it.

RECENT FINDINGS

Published reports during the past year focus on the pathophysiology of coagulopathy after trauma and novel methods of treatment. Individual effects of hypothermia and acidosis on clotting factors and platelet function have been described. The effects of varying resuscitation fluids on coagulopathy have also been described as well as the course of coagulopathy over time. Recombinant factor VIIa has emerged as a popular therapy for traumatic coagulopathy although a prospective randomized trial has yet to be published. The efficacy of several new dressings for the local control of hemorrhage has been reported.

SUMMARY

Changes in coagulation following trauma are characterized by a complex series of events that may result in either a hypocoagulable or a hypercoagulable state. Routinely analyzed coagulation parameters do not adequately describe this state and they are deficient for guiding its therapy. Several promising new agents are available for treating hemorrhage in coagulopathic trauma patients that should result in improved survival.

Hypercoagulability Is Most Prevalent Early after Injury and in Female Patients

BACKGROUND

Hypercoagulability after injury is a major source of morbidity and mortality. Recent studies indicate that there is a gender-specific risk in trauma patients. This study was performed to determine the course of coagulation after injury and to determine whether there is a gender difference. We hypothesized that hypercoagulability would occur early after injury and that there would be no difference between men and women.

METHODS

This was a prospective cohort study. Inclusion criteria were admission to the intensive care unit, Injury Severity Score > 4, and the ability to obtain consent from the patient or a relative. A Thrombelastograph (TEG) analysis was performed and routine coagulation parameters and thrombin-antithrombin complexes were measured within 24 hours of injury and then daily for 4 days.

RESULTS

Sixty-five patients met criteria for entry into the study. Their mean age was 42 +/- 17 years and their mean Injury Severity Score was 23 +/- 12. Forty patients (62%) were men. The prevalence of a hypercoagulable state by TEG was 62% on day 1 and 26% on day 4 (p < 0.01). Women were significantly more hypercoagulable on day 1 than men as measured by the time to onset of clotting (women, 2.9 +/- 0.7 minutes; men, 3.9 +/- 1.5 minutes; p < 0.01; normal, 3.7-8.3 minutes). Mean platelet counts, international normalized ratios, and partial thromboplastin times were within normal limits throughout the study. Thrombin activation as measured by thrombin-antithrombin complexes decreased from 34 +/- 15 microg/L on day 1 to 18 +/- 8 microg/L (p < 0.01) on day 4, consistent with the prevalence of hypercoagulability by TEG.

CONCLUSION

Hypercoagulability after injury is most prevalent during the first 24 hours. Women are more hypercoagulable than men early after injury. The TEG is more sensitive than routine coagulation assays for the detection of a hypercoagulable state.

Effective attenuation of endotoxin-induced acute lung injury by 2,3-diacetyloxybenzoic acid in two independent animal models

The pathology of acute lung injury (ALI) is often modeled in animal studies by the administration of lipopolysaccharide (LPS), which results in an endotoxemia with sequelae similar to that seen in acute respiratory distress syndrome (ARDS). Here we report the results of two studies designed to examine the efficacy of a novel agent, 2,3-diacetyloxybenzoic acid (2,3-DABA), in the treatment of LPS-induced ALI. In two separate animal models, 2,3-DABA was effective in significantly reducing lung microvascular permeability, a condition commonly seen in ARDS, which results in pulmonary edema and respiratory insufficiency. In each model, it is demonstrated that the mechanism by which 2,3-DABA exerts this effect occurs subsequent to the recruitment of neutrophils to the site of inflammation. Lung permeability was significantly decreased in both models by treatment with 2,3-DABA, suggesting that this agent, either alone or in combination therapy, may be useful in the treatment of ALI associated with ARDS.

Plasma protein Z levels in healthy and high-risk newborn infants

AIM

To evaluate plasma protein Z (PZ) levels in healthy and high-risk newborn infants.

METHODS

A longitudinal observational study was conducted. Inclusion criteria were: healthy term and preterm newborns normal for gestational age and newborns belonging to one of the following groups: newborns small for gestational age (SGA), newborns affected by respiratory distress syndrome (RDS), newborns from mothers with pre-eclampsia. Newborns with sepsis, congenital malformation or haemorrhagic disorders were excluded. Plasma PZ levels, protein C (PC) concentration, PC activity and protein-induced vitamin K absence levels were measured.

RESULTS

53 newborns were enrolled into the study. PZ and PC antigen levels varied significantly among analysed subgroups on day 1 (p < 0.01): lower levels of these inhibitors were found in RDS newborns (group C), newborns from mothers affected by pre-eclampsia (group D) and SGA newborns (group E) than in healthy term and preterm newborns (groups A and B).

CONCLUSION

PZ deficiency occurs in newborns affected by severe RDS, in newborns from pre-eclamptic mothers and in SGA newborns, probably owing to activated coagulation in the first two conditions and to reduced PZ synthesis in the last condition.

Bronchoalveolar coagulation and fibrinolysis in endotoxemia and pneumonia

OBJECTIVES

To review the involvement of coagulation and fibrinolysis in the pathogenesis of acute lung injury during severe infection. To review the cross-talk between coagulation and inflammation that may affect this response.

DATA SOURCES

Published articles on experimental and clinical studies of coagulation and fibrinolysis during infection, inflammation, acute lung injury, and evolving acute respiratory distress syndrome.

CONCLUSIONS

Fibrin deposition is an important feature of pulmonary infection or severe inflammation. The mechanisms that contribute to this fibrin deposition are bronchoalveolar tissue factor-mediated thrombin generation and localized depression of urokinase plasminogen activator-mediated fibrinolysis, caused by the increase of plasminogen activator inhibitors. These effects on pulmonary coagulation and fibrinolysis are regulated by various proinflammatory cytokines. Rather than being a unidirectional relationship, the interaction between inflammation and coagulation involves significant cross-talk. Coagulation and fibrinolytic proteins may have an additional role beyond fibrin turnover and inflammation, e.g., in mechanisms mediating cell recruitment and migration.

Gabexate mesilate, a synthetic anticoagulant, inhibits the expression of endothelial leukocyte adhesion molecules in vitro

OBJECTIVE

Gabexate mesilate, a synthetic protease inhibitor, has been shown to reduce endotoxin-induced pulmonary vascular injury in an animal model of sepsis by inhibiting leukocyte activation. We examined whether gabexate mesilate inhibits tumor necrosis factor-alpha-induced expression of leukocyte adhesion molecules in cultured endothelial cells.

DESIGN

Prospective, randomized, controlled study.

SETTING

Research laboratory at a university medical center.

SUBJECTS

Cultured human umbilical vein endothelial cell (HUVECs).

INTERVENTIONS

HUVECs were stimulated with tumor necrosis factor-alpha or lipopolysaccharide in the presence or absence of gabexate mesilate. Expression of E-selectin and intercellular adhesion molecule-1 was measured by cellular enzyme-linked immunosorbent assay. Messenger RNA levels of E-selectin and intercellular adhesion molecule-1 were determined by reverse transcription-polymerase chain reaction. DNA-binding activity of p65 in the nuclear extracts was evaluated by enzyme-linked immunosorbent assay. Nuclear translocation of nuclear factor-kappaB induced by tumor necrosis factor-alpha was evaluated by immunocytostaining and Western blot analysis. Degradation and phosphorylation of inhibitor of nuclear factor-kappaB (IkappaB) induced by tumor necrosis factor-alpha were evaluated by Western blot analysis.

MEASUREMENTS AND MAIN RESULTS

Gabexate mesilate inhibited the tumor necrosis factor-alpha-induced increases in the endothelial expression of E-selectin and intercellular adhesion molecule-1 by inhibiting the transcription. Tumor necrosis factor-alpha-induced increase in DNA binding of p65 was inhibited by gabexate mesilate through inhibition of the nuclear translocation of p65. Gabexate mesilate inhibited the tumor necrosis factor-alpha-induced degradation of IkappaBalpha, an inhibitor of nuclear factor-kappaB, by inhibiting phosphorylation of IkappaBalpha in HUVECs.

CONCLUSIONS

Gabexate mesilate inhibited the expression of leukocyte adhesion molecules by inhibiting the nuclear factor-kappaB-mediated transcription in HUVECs. Inhibition of nuclear factor-kappaB activation by gabexate mesilate could be explained by inhibition of degradation of IkappaB. Gabexate mesilate might reduce lipopolysaccharide-induced pulmonary vascular injury not only by inhibiting monocytic tumor necrosis factor-alpha production but by inhibiting the expression of endothelial leukocyte adhesion molecules.

Imbalances between the levels of tissue factor and tissue factor pathway inhibitor in ARDS patients

INTRODUCTION

To evaluate the pathogenetic role of tissue factor (TF), tissue factor pathway inhibitor (TFPI), and neutrophil elastase in acute respiratory distress syndrome (ARDS), as well as to test the hypothesis that TFPI levels modified by neutrophil activation are not sufficient to prevent TF-dependent intravascular coagulation, leading to sustained systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS), which determine the prognosis of these patients.

MATERIALS AND METHODS

The study subjects consisted of 55 patients with trauma and sepsis who were divided into three groups according to the Lung Injury Score. Ten normal healthy volunteers served as control. Plasma levels of TF, TFPI, and neutrophil elastase were measured on the day of injury or the day of diagnosis of sepsis (day 0) and days 1 through 4. The number of SIRS criteria that the patient met and the disseminated intravascular coagulation (DIC) score is determined daily.

RESULTS

Patients (15) developed ARDS, 23 were at risk for but did not develop the syndrome, and 17 patients were without risk for ARDS. TF and neutrophil elastase levels in ARDS patients were persistently higher than those in other two groups and control subjects. However, the TFPI levels showed no difference among the three groups, which retained normal or slightly elevated levels compared to the control subjects. DIC scores did not improve and SIRS continued during the study period in patients with ARDS. The ARDS patients showed higher numbers of dysfunctioning organs and associated with poorer outcome than the other two groups.

CONCLUSION

Systemic activation of the TF-dependent pathway not adequately balanced by TFPI is one of the aggravating factors of ARDS. High levels of neutrophil elastase released from activated neutrophils may explain the imbalance of TF and TFPI. Persistent DIC and sustained SIRS contribute to MODS, determining the prognosis of ARDS patients.

Pharmacology of acute lung injury

The acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a clinical syndrome that affects both medical and surgical patients. To date, despite improved understanding of the pathogenesis of ALI/ARDS, pharmacological modalities have been unsuccessful in decreasing mortality. However, several pharmacological agents for ARDS are in development and have shown great promise. In addition to the anti-inflammatory category including late corticosteroids, inhaled nitric oxide, alveolar surfactant, and vasodilators are being evaluated. Replacements of anticoagulation mediators have also suggested beneficial effects on the patient outcome. This article provides an overview of pharmacological treatments of ALI/ARDS.

Venous thromboembolism and its prevention in critical care

BACKGROUND

Evidence-based guidelines for the prevention of venous thromboembolism (VTE) are available for most major surgical and medical patient groups. Such guidelines have not been established for critically ill patients.

OBJECTIVE

To perform a systematic review of the prevalence of deep vein thrombosis (DVT), the efficacy of thromboprophylaxis, and the rates of thromboprophylaxis use in critically ill patients.

METHODS

Computerized literature search for relevant studies meeting prespecified criteria.

RESULTS

The rates of objectively confirmed DVT in 4 prospective studies ranged from 13% to 31%. We identified only 3 randomized trials (1 in abstract form) of thromboprophylaxis in critical care unit patients. These studies show the efficacy of low-dose heparin and low molecular weight heparin compared with no prophylaxis; however, we found no trials comparing these 2 interventions. Eleven compliance studies reported that some form of thromboprophylaxis was used in 33% to 100% of critically ill patients, although only 1 study addressed the issue of appropriate prophylaxis use.

CONCLUSIONS

Data on the epidemiology of VTE and its prevention in critically ill patients are very limited. Further research is needed to better define patient risk factors for VTE, optimal methods of thromboprophylaxis, and strategies to improve compliance with prophylaxis recommendations. In the meantime, prevention strategies, shown to be effective in other related patient groups, and general principles of individual pharmacotherapy should guide the routine use of prophylaxis during critical illness.

Global fibrinolytic capacity in early respiratory distress syndrome: a pilot study

Fibrin deposits found in the pulmonary microcirculation and in the small airways of preterm infants with severe respiratory distress syndrome (RDS) has been explained by the activation of the coagulation system and/or insufficient fibrinolysis. Previous studies suggest that disseminated intravascular coagulation is not prominent in the early stages of RDS, and there is a reduced fibrinolytic activity in these patients. The in vitro evaluation of body's fibrinolytic potential is difficult in contrast to blood clotting because fibrinolysis is only activated after coagulation. To solve this problem a standardized assay was developed to measure the global fibrinolytic capacity (GFC) in plasma. This assay allows us a sensitive and reliable parameter to evaluate the fibrinolytic potency of plasma in vitro. We therefore studied GFC in the first 6 hr after birth in preterm infants who later developed RDS. Global fibrinolytic capacity which is expressed as generated D-dimer concentrations was significantly lower in preterm infants who later developed RDS compared to the control group in this study. These findings support our previous hypothesis of "reduced fibrinolytic state in early RDS".

Taurolidine attenuates the hemodynamic and respiratory changes associated with endotoxemia

The purpose of this study was to determine if prereatment with taurolidine, a known anti-endotoxin agent, would attenuate the hemodynamic and respiratory responses associated with endotoxin induced lung injury in a large animal model in a randomized controlled study under license from the Department of Health. All animals underwent a general anesthetic. Vascular catheters were placed in the femoral artery and in the femoral vein. A Swan-Ganz Catheter was inserted for measurement of pulmonary artery pressure. Animals were randomized into three groups: Control, with measurements taken at baseline and half hourly up to 90 min; Endotoxin, receiving 5microg/Kg E. coli endotoxin intravenously after baseline measurements; and Endotoxin + Taurolidine, receiving 5g of taurolidine via intraperitoneal infusion 1 h before endotoxin administration. Main outcome measures were mean systemic arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), arterial oxygen tension (pO2), serum endotoxin concentration, and pulmonary myeloperoxidase. Endotoxin induced a significant lung injury characterized by an increase in pulmonary artery pressure, hypoxia, and systemic hypotension. Pretreatment with intraperitoneal taurolidine significantly attenuated these hemodynamic and respiratory changes. Serum endotoxin concentration was also significantly reduced as was lung myeloperoxidase. The data suggest that taurolidine may have a therapeutic role in preventing the lung injury seen in endotoxemia.

Treatment of Severe Acute Respiratory Distress Syndrome: A Final Report on a Phase I Study

Adult respiratory distress syndrome (ARDS) has a high mortality. Its only effective treatment is respiratory therapy. If this fails mortality is probably 100 per cent. No other treatment for ARDS has proved effective including “magic bullets.” Twenty patients suffering from ARDS secondary to trauma and/or sepsis failed to respond to treatment with mechanical ventilation and positive end-expiratory pressure. On the assumption that disseminated intravascular coagulation initiates ARDS by occluding the pulmonary microcirculation with microclots, the patients were treated with plasminogen activators. The patients responded with significant improvement in partial pressure of oxygen in arterial blood. No bleeding occurred and clotting parameters remained normal. We conclude that ARDS can be safely treated with plasminogen activator.

Taurine attenuates LPS-induced rolling and adhesion in rat microcirculation

BACKGROUND

Adhesion of polymorphonuclear leukocytes (PMN) to endothelial cells and subsequent transendothelial migration are an early key events in the inflammatory response and play an important part in the pathogenesis of septic shock, contributing to vascular and tissue injury. Taurine (2-aminoethanesulfonic acid) is a sulphur-containing beta amino acid. It is a known antioxidant, possesses antimicrobial properties, and has previously been shown to be protective to the endothelium both in vivo and in vitro. The aim of this study was to determine if pretreatment with taurinewould attenuate the lipopolysaccharide (LPS)-induced increase in leukocyte-endothelial interactions and microvascular permeability during endotoxemia.

MATERIALS AND METHODS

Male Sprague-Dawley rats (300-350 g) were randomized into three groups: (1) Control, (2) LPS, and (3) LPS + Taurine groups. Taurine was administered orally as a 4% solution. Endotoxemia was induced using Escherichia Coli endotoxin (Serotype 0.55 B5)-15 mg/kg via a slow intravenous infusion. Using mesenteric postcapillary venules (28-32-microm diameter) the number of adherent and migrated leukocytes and their rolling velocity were measured by intravital microscopy at baseline and subsequently at 10, 30, 60, and 90 min post administration of LPS.

RESULTS

Following administration of LPS there was a reduction in leukocyte rolling velocity at 30, 60 and 90 min. This was accompanied by a significant increase in the number of adherent leukocytes at 10, 30, 60 and 90 min. Transendothelial migration was significantly increased at 90 min. Taurine significantly attenuated the LPS-induced reduction in leukocyte rolling velocity at 10 and 30 min and the number of adherent leukocytes at all time points. Taurine also attenuated the LPS-induced increase in transendothelial migration at 90 min.

CONCLUSIONS

These results demonstrate that taurine ameliorates endotoxin-induced leukocyte-endothelial cell interactions associated with sepsis, thereby suggesting that taurine may have a therapeutic role in the preventionof endothelial damage in sepsis.

Hemorrhagic fever virus-induced changes in hemostasis and vascular biology

Viral hemorrhagic fever (VHF) denotes a virus-induced acute febrile, hemorrhagic disease reported from wide areas of the world. Hemorrhagic fever (HF) viruses are encapsulated, single-stranded RNA viruses that are associated with insect or rodent vectors whose interaction with humans defines the mode of disease transmission. There are 14 HF viruses, which belong to four viral families: Arenaviridae, Bunyaviridae, Filoviridae and Flaviviridae. This review presents, in order, the following aspects of VHF: (1) epidemiology, (2) anomalies of platelets and coagulation factors, (3) vasculopathy, (4) animal models of VHFs, (5) pathogenic mechanisms, and (6) treatment and future studies. HF viruses produce the manifestations of VHFs either by direct effects on cellular functions or by activation of immune and inflammatory pathways. In Lassa fever, Rift Valley fever and Crimean-Congo HF, the main feature of fatal illness appears to be impaired/delayed cellular immunity, which leads to unchecked viremia. However, in HF with renal syndrome and dengue HF, the immune response plays an active role in disease pathogenesis. The interplay of hemostasis, immune response, and inflammation is very complex. Molecular biologic techniques and the use of animal models have helped to unravel some of these interactions.

Systemic activation of tissue-factor dependent coagulation pathway in evolving acute respiratory distress syndrome in patients with trauma and sepsis

BACKGROUND

Extravascular coagulation and fibrin deposition coupled with perturbations of intravascular coagulation occurs in association with acute respiratory distress syndrome (ARDS). To evaluate the pathogenetic role of an extrinsic coagulation pathway in the intravascular coagulation of ARDS patients and to explore the time course of the changes of tissue factor levels, platelet counts, and disseminated intravascular coagulation (DIC), we performed a prospective cohort study.

METHODS

The study subjects consisted of 113 patients: 27 patients with ARDS, 31 patients at risk for but not developing the syndrome, and 55 patients without ARDS. According to the underlying disease, the patients were further subdivided into two groups: patients with trauma (n = 76) and patients with sepsis (n = 37). Ten normal healthy volunteers served as control subjects. Plasma tissue factor antigen (tissue factor) levels and platelet counts were measured on the day of admission and on days 1 through 4 after admission. Simultaneously, the DIC scores were determined.

RESULTS

The values of tissue factor in the patients with ARDS were significantly more elevated than those measured in the other two groups (p < 0.001) and control subjects (p < 0.001) on the day of admission. The values continued to be markedly high up to day 4 of admission. On the day of admission, the platelet counts in the ARDS patients showed significantly lower values (p < 0.05) than those in the other two groups. The incidence of DIC and the DIC scores in ARDS patients were significantly higher than those in the other two groups. The tissue factor levels (r(s) = 0.428, p < 0.0001) and DIC scores (r(s) = 0.357, p < 0.0002) correlated significantly with Lung Injury Score. When the patients were subdivided into two subgroups, i.e., trauma and sepsis, some differences of the tissue factor levels were noted between the two groups.

CONCLUSION

We demonstrated that tissue-factor dependent coagulation pathway of plasma is extensively activated in patients with ARDS, followed by intravascular coagulation and platelet consumption. We further provide precise information on the time course of tissue factor levels and DIC in patients with ARDS and those at risk for developing this syndrome.

Contrasting post-traumatic serial changes for D-dimer and PAI-1 in critically injured patients

We measured D-dimer and plasminogen activator inhibitor-1 (PAI-1) activity in 45 trauma patients to assess their efficacy in predicting the post-traumatic hemostatic perturbations. We found the correlation between D-dimer measured by Simpli Red test and ELISA to be highly significant (p=0.0001). The D-dimer ELISA indicated that the serial changes of D-dimer after trauma were variable. However, the increases of D-dimer were associated with clinical conditions of the patient, such as trauma surgery, infections, or thrombotic complications. A significant correlation was found for D-dimer levels measured by ELISA versus the injury severity score (ISS) in all the trauma patients on day 1 (p=0.0153) and on day 2 (p=0.0495). The PAI-1 activity was increased at admission and showed a progessive decline from day 2 onward, and the correlation for the daily decline of PAI-1 was highly significant (p=0.0001). The PAI-1 activity and plasminogen activator activity showed a significant negative correlation on days 1, 2, and 3. PAI-1 activity correlated moderately with D-dimer level only on day 1 (p=0.0569). Three out of forty-five patients developed thrombotic complications: one patient who died from pulmonary embolism and two patients who developed adult respiratory distress syndrome (ARDS). In summary: 1) PAI-1 activity and D-dimer exhibited contrasting serial changes after trauma. 2) There was also a negative correlation between PAI-1 activity and PA activity. 3) A significant correlation of D-dimer with ISS confirms, as might be anticipated, that there is increased activation of the coagulation mechanism in severe injury, and suggests that D-dimer levels may prove useful to screen for patients at strong risks of thrombotic complications.

Glucocorticoid attenuates a decrease of antithrombin III following major surgery

BACKGROUND

Major surgery, such as esophagectomy, activates inflammatory responses and the coagulation system, and this activation is characterized by release of inflammatory cytokines and a decrease in antithrombin-III (AT-III), respectively. Preoperative glucocorticoid administration has been reported to suppress circulatory cytokine levels after major surgery.

PATIENTS AND METHODS

A total of 28 patients underwent esophagectomy for esophageal carcinoma; 14 of them were given 10 mg/kg of methylprednisolone intravenously upon induction of anesthesia and 14 served as controls. Circulating levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), polymorphonuclear (PMN) elastase, thrombin-antithrombin III complex (TAT), AT-III, and albumin were measured before and immediately after the operation and on postoperative days (PODs) 1, 3, 5, and 7.

RESULTS

TNF-alpha, IL-6, and TAT levels significantly increased after esophagectomy in both groups. AT-III and albumin decreased to their minimum levels on POD 1 and POD 3, respectively. Methylprednisolone treatment effectively inhibited the increases in TNF-alpha and IL-6 and the decreases in AT-III and albumin, but did not inhibit the increases in PMN-elastase and TAT levels. There were significant correlations between AT-III, IL-6, and albumin levels.

CONCLUSIONS

These results suggest that methylprednisolone pretreatment attenuates the decrease in AT-III by reducing IL-6 production postoperatively.

Impact of inhaled nitric oxide on platelet aggregation and fibrinolysis in rats with endotoxic lung injury. Role of cyclic guanosine 5'-monophosphate

As inhaled nitric oxide (iNO) may differently increase bleeding time (BT) and inhibit platelet aggregation in normal and lung-injured patients or experimental models, we studied the effects of iNO on hemostasis in presence and absence of an endotoxic lung injury in the rat. Eight hours after intratracheal administration of endotoxin (lipopolysaccharide [LPS]) or its solvent (phosphate-buffered solution [PBS]), four groups of rats were randomized according to the presence or absence of 15 ppm iNO added for an additional 10 h. We measured BT, ex vivo platelet aggregation, plasma fibrinogen, euglobulin clot lysis time (ECLT), and platelet and aortic cyclic guanosine 5'-monophosphate (cGMP) contents. Acute lung inflammation did not influence BT, but increased platelet aggregability, fibrinogen levels, and platelet and aortic cGMP. In control and endotoxic rats, iNO increased BT, reduced platelet aggregability, and increased platelet cGMP. iNO increased aortic cGMP only in healthy rats. ECLT was increased by LPS and unchanged with iNO. These results suggest that the extrapulmonary "systemic" effects induced by iNO on hemostasis were not strictly similar in healthy and LPS rats, inflammation inducing proper changes in coagulation parameters. However, iNO attenuated the procoagulant activity induced by acute lung inflammation, suggesting a potentially beneficial effect of this therapy.

Differential effects of anti-cytokine treatment on bronchoalveolar hemostasis in endotoxemic chimpanzees

Activation and inhibition of coagulation and fibrinolysis was analyzed in bronchoalveolar lavage (BAL) fluids obtained from endotoxin-challenged chimpanzees. The mediatory role of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) on endotoxin-induced changes in bronchoalveolar coagulation and fibrinolysis was investigated in experiments in which the infusion of endotoxin was combined with the administration of monoclonal anti-TNF-alpha or anti-IL-6 antibodies. Endotoxin infusion elicited a marked increase in bronchoalveolar thrombin generation as measured by levels of prothrombin activation fragment F1+2 and thrombin-antithrombin complexes. Markers for intrinsic pathway activation were not detectable, suggesting that the thrombin generation was mediated by the tissue factor-dependent route. Levels of antithrombin were low before the injection of endotoxin and not detectable hereafter. The administration of anti-IL-6 antibody completely abolished the endotoxin-induced activation of bronchoalveolar coagulation, whereas treatment with anti-TNF-alpha antibody only partly inhibited this effect. Bronchoalveolar fibrinolytic activity, due to urokinase-type plasminogen activator (u-PA), was significantly depressed after endotoxin injection, mainly due to a striking increase in plasminogen activator inhibitor-2 levels in BAL fluid. The endotoxin-induced effects on bronchoalveolar fibrinolysis could be blocked by the simultaneous administration of anti- TNF-alpha antibodies. We conclude that endotoxemia results in the activation of bronchoalveolar coagulation, which is apparently mediated by the tissue factor route of coagulation activation and which may be amplified by consumption of antithrombin III. Bronchoalveolar fibrinolytic activity is significantly abolished by increased levels of mainly PAI-2 after the injection of endotoxin. The endotoxin-induced effects on bronchoalveolar coagulation appears to be mediated by IL-6, whereas TNF-alpha seems to be the pivotal mediator of the endotoxin-induced depression of bronchoalveolar fibrinolysis.

Effects of various doses of antithrombin III on endotoxin-induced endothelial cell injury and coagulation abnormalities in rats

We previously demonstrated that antithrombin III reduced the injury to endothelial cells caused by activated leukocytes in rats administered endotoxin. This occurred via the increase of the endothelial release of prostaglandin I2, which is a potent inhibitor of leukocyte activation. We evaluated the dose of antithrombin III required to prevent such endothelial cell injury in rats administered endotoxin, by comparing the effects of various antithrombin II doses on the pulmonary vascular injury. The intravenous administration of endotoxin, 5 mg/kg, produced a transient accumulation of leukocytes in the lung, followed by pulmonary vascular injury, as indicated by an increase in the pulmonary vascular permeability, and coagulation abnormalities. The dose of 250 U/kg significantly inhibited all such effects of endotoxin. While lower doses of antithrombin III (50 and 100 U/kg) significantly inhibited such coagulation abnormalities, they failed to prevent either the pulmonary accumulation of leukocytes or the subsequent pulmonary vascular injury. Rats administered endotoxin exhibited an accumulation of neutrophils and edematous changes in the pulmonary interstitial space. Although such changes were reduced after 250 U/kg of antithrombin III, they were unaffected by lower doses of 50 and 100 U/kg. Plasma levels of 6-keto-PGF1alpha were markedly increased in rats 90 min after the administration of endotoxin, and were significantly decreased in the endotoxin-treated rats administered the lower doses of antithrombin III (50 and 100 U/kg), but not altered in those endotoxin-treated rats receiving 250 U/kg of antithrombin III. These findings suggest that a higher antithrombin III dose is necessary to prevent endothelial cell injury than is required to inhibit coagulation abnormalities in an animal model of sepsis. These observations support the notion that antithrombin III may prevent endotoxin-induced endothelial cell injury by promoting endothelial release of prostaglandin I2 and thus inhibiting leukocyte activation.

Nitric oxide inhalation inhibits platelet aggregation and platelet-mediated pulmonary thrombosis in rats

Endothelium-derived nitric oxide (NO) inhibits in vitro platelet aggregation via a cGMP-dependent mechanism. The effect of inhaled NO on platelet-mediated pulmonary thrombosis following intravenous thrombotic challenge with collagen was examined in rats and compared with the effect of G4120, a cyclic Arg-Gly-Asp-containing synthetic pentapeptide that binds to the platelet glycoprotein IIb/IIIa receptor. Intraplatelet cGMP dose-dependently increased from 39 +/- 6 fmol/10(8) platelets in control to 46 +/- 6, 68 +/- 13, and 81 +/- 13 fmol/10(8) platelets after inhalation with 20, 40, and 80 ppm NO, respectively (P < .05 for 40 and 80 ppm). Ex vivo platelet aggregation of platelet-rich plasma induced by 1 microgram/mL collagen was reduced from 75 +/- 4% in control rats to 22 +/- 10% and 20 +/- 7% in rats ventilated with 40 and 80 ppm NO, respectively, and to 30 +/- 9% in G4120-treated rats (each P < .05 versus control). Circulating platelet counts 3 minutes after collagen injection were significantly higher in the inhaled NO and G4120 groups compared with control rats (250,000 +/- 18,000 and 223,000 +/- 10,000/microL versus 160,000 +/- 18,000/microL, each P < .05). The rise in pulmonary arterial pressure after collagen injection was significantly reduced in NO- and G4120-treated rats (26 +/- 1 and 27 +/- 1 versus 32 +/- 1 mm Hg in control rats, each P < .05). The number of pulmonary resistance vessels containing platelet thrombi was significantly smaller after inhaled NO and G4120 treatment compared with control (56 +/- 3% and 50 +/- 3% versus 68 +/- 3%, respectively; P < .05). Thus, NO inhalation reduces in vivo activation of circulating platelets and platelet-rich thrombosis in thromboembolic pulmonary hypertension. Inhalation of NO may be useful in cardiovascular diseases associated with platelet activation.

rhs-TM prevents ET-induced increase in pulmonary vascular permeability through protein C activation

We have previously demonstrated that recombinant human soluble (rhs) thrombomodulin (TM) inhibits the endotoxin (ET)-induced increase in pulmonary vascular permeability by inhibiting leukocyte activation. In the present study, we examined whether rhs-TM could inhibit the ET-induced increase in pulmonary vascular permeability in rats by activating protein C. rhs-TM did not inhibit ET-induced increases in pulmonary vascular permeability when its protein C activation ability was selectively inhibited by a monoclonal antibody (MAb) against rhs-TM (MAb R5G12). Histological examination revealed that neutrophil infiltration in lung tissues after ET administration was significantly reduced by rhs-TM, but infiltration was not reduced by MAb R5G12-pretreated rhs-TM. ET-induced intravascular coagulation was prevented by rhs-TM and by MAb R5G12-pretreated rhs-TM. However, ET-induced coagulation was not prevented by rhs-TM that had been treated with MAb F2H5, which cannot bind thrombin or activate protein C. These observations strongly suggest that rhs-TM prevents ET-induced pulmonary vascular injury by inhibiting pulmonary accumulation of leukocytes through thrombin binding and the subsequent protein C activation and may prevent ET-induced intravascular coagulation through thrombin binding.

Increased neutrophil elastase, persistent intravascular coagulation, and decreased fibrinolytic activity in patients with posttraumatic acute respiratory distress syndrome

BACKGROUND

To investigate the role of plasma neutrophil elastase (elastase-alpha1-proteinase inhibitor complex), plasminogen activator inhibitor-1 (PAI-1), and disseminated intravascular coagulation (DIC) in patients with posttraumatic acute respiratory distress syndrome (ARDS) and to explore the time course of the changes of these factors after trauma, we performed a prospective case-control study.

METHODS

The study subjects consisted of 41 trauma patients, 5 with ARDS, 7 at risk for but not developing the syndrome, and 29 control patients without or with no risk for ARDS. Plasma neutrophil elastase, PAI-1 activity, and PAI-1 antigen concentration were measured on the day of the injury and on days 1, 3, and 5 after admission. DIC was measured on the basis of the DIC score. The results of these measurements and demographic data were compared among the three groups.

RESULTS

Neutrophil elastase, PAI-1 activity, and PAI-1 antigen concentration for the ARDS patients continued to be markedly high until the fifth day of admission, and the values on the fifth day were significantly higher than those of the other two groups. All patients with ARDS developed DIC. A decrease in the DIC score was found for the control patients and also for the patients at risk for ARDS; however, for the patients with ARDS, the DIC score did not improve during the study period (p = 0.5809).

CONCLUSION

We provide precise information on the time course of neutrophil elastase, PAI-1, and DIC in trauma patients with ARDS and those at risk of developing this syndrome. Neutrophil activation and persistent intravascular coagulation as well as impaired fibrinolysis may play a role in the pathogenesis of posttraumatic ARDS.

Effect of human urinary thrombomodulin on endotoxin-induced intravascular coagulation and pulmonary vascular injury in rats

Adult respiratory distress syndrome (ARDS) and disseminated intravascular coagulation (DIC) are serious complications of sepsis. Thrombomodulin, an important endothelial anticoagulant, binds thrombin to generate activated protein C (APC). To determine whether thrombomodulin purified from human urine (urinary thrombomodulin, UTM) is useful for the treatment of DIC and ARDS in sepsis, we examined the effect of UTM on endotoxin (ET)-induced coagulation abnormalities and pulmonary vascular injury in rats. Intravenous administration of UTM prevented the ET-induced pulmonary accumulation of leukocytes and the increase in pulmonary vascular permeability, as well as ET-induced histological changes such as leukocyte infiltration and pulmonary interstitial edema. On the other hand, dansyl-Glu-Gly-Arg-chloromethyl ketone-treated factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, did not prevent these effects of ET. UTM did not prevent ET-induced pulmonary accumulation of leukocytes and pulmonary vascular injury in rats pretreated with DEGR-Xa. Our findings suggest that UTM attenuates ET-induced coagulation abnormalities and pulmonary vascular injury. Furthermore, the latter effect may be dependent on the capacity of UTM to activate protein C.

Endotoxin-induced pulmonary vascular injury is mainly mediated by activated neutrophils in rats

Acute respiratory failure is a common complication in patients with disseminated intravascular coagulation associated with sepsis. To elucidate the role of coagulation abnormalities in acute lung injury in sepsis, we investigated the effect of anticoagulants on the pulmonary vascular injury in rat induced by lipopolysaccharide (LPS). When administered intravenously, LPS (5 mg/kg body weight) significantly increased the accumulation of 111indium-labeled neutrophils in lung 30 min after administration. Subsequently, the pulmonary vascular permeability and the serum level of fibrin and fibrinogen degradation products (E) [FDP (E)] increased and remained elevated for several hours. Neither heparin alone, heparin plus antithrombin III, or dansyl-Glu-Gly-Arg-chloromethyl ketone-treated factor Xa, a selective inhibitor of thrombin generation, prevented LPS-induced vascular injury 6 hours after LPS administration, whereas these substances significantly inhibited the increase in serum FDP (E) at that time. LPS-induced pulmonary vascular injury was significantly attenuated in rats with methotrexate-induced leukocytopenia or treated with ONO-5046, a potent granulocyte elastase inhibitor, although ONO-5046 did not inhibit the LPS-induced increase in serum FDP (E). Thus, activated leukocytes play a more important role than coagulation abnormalities in the pathogenesis of LPS-induced pulmonary vascular injury in an experimental rat model of endotoxemia.