Respiratory drive heterogeneity associated with systemic inflammation and vascular permeability in acute respiratory distress syndrome

BACKGROUND

In acute respiratory distress syndrome (ARDS), respiratory drive often differs among patients with similar clinical characteristics. Readily observable factors like acid-base state, oxygenation, mechanics, and sedation depth do not fully explain drive heterogeneity. This study evaluated the relationship of systemic inflammation and vascular permeability markers with respiratory drive and clinical outcomes in ARDS.

METHODS

ARDS patients enrolled in the multicenter EPVent-2 trial with requisite data and plasma biomarkers were included. Neuromuscular blockade recipients were excluded. Respiratory drive was measured as PES0.1, the change in esophageal pressure during the first 0.1 s of inspiratory effort. Plasma angiopoietin-2, interleukin-6, and interleukin-8 were measured concomitantly, and 60-day clinical outcomes evaluated.

RESULTS

54.8% of 124 included patients had detectable respiratory drive (PES0.1 range of 0-5.1 cm H2O). Angiopoietin-2 and interleukin-8, but not interleukin-6, were associated with respiratory drive independently of acid-base, oxygenation, respiratory mechanics, and sedation depth. Sedation depth was not significantly associated with PES0.1 in an unadjusted model, or after adjusting for mechanics and chemoreceptor input. However, upon adding angiopoietin-2, interleukin-6, or interleukin-8 to models, lighter sedation was significantly associated with higher PES0.1. Risk of death was less with moderate drive (PES0.1 of 0.5-2.9 cm H2O) compared to either lower drive (hazard ratio 1.58, 95% CI 0.82-3.05) or higher drive (2.63, 95% CI 1.21-5.70) (p = 0.049).

CONCLUSIONS

Among patients with ARDS, systemic inflammatory and vascular permeability markers were independently associated with higher respiratory drive. The heterogeneous response of respiratory drive to varying sedation depth may be explained in part by differences in inflammation and vascular permeability.

Rapidly improving ARDS differs clinically and biologically from persistent ARDS

BACKGROUND

Rapidly improving acute respiratory distress syndrome (RIARDS) is an increasingly appreciated subgroup of ARDS in which hypoxemia improves within 24 h after initiation of mechanical ventilation. Detailed clinical and biological features of RIARDS have not been clearly defined, and it is unknown whether RIARDS is associated with the hypoinflammatory or hyperinflammatory phenotype of ARDS. The purpose of this study was to define the clinical and biological features of RIARDS and its association with inflammatory subphenotypes.

METHODS

We analyzed data from 215 patients who met Berlin criteria for ARDS (endotracheally intubated) and were enrolled in a prospective observational cohort conducted at two sites, one tertiary care center and one urban safety net hospital. RIARDS was defined according to previous studies as improvement of hypoxemia defined as (i) PaO2:FiO2 > 300 or (ii) SpO2: FiO2 > 315 on the day following diagnosis of ARDS (day 2) or (iii) unassisted breathing by day 2 and for the next 48 h (defined as absence of endotracheal intubation on day 2 through day 4). Plasma biomarkers were measured on samples collected on the day of study enrollment, and ARDS phenotypes were allocated as previously described.

RESULTS

RIARDS accounted for 21% of all ARDS participants. Patients with RIARDS had better clinical outcomes compared to those with persistent ARDS, with lower hospital mortality (13% vs. 57%; p value < 0.001) and more ICU-free days (median 24 vs. 0; p value < 0.001). Plasma levels of interleukin-6, interleukin-8, and plasminogen activator inhibitor-1 were significantly lower among patients with RIARDS. The hypoinflammatory phenotype of ARDS was more common among patients with RIARDS (78% vs. 51% in persistent ARDS; p value = 0.001).

CONCLUSIONS

This study identifies a high prevalence of RIARDS in a multicenter observational cohort and confirms the more benign clinical course of these patients. We report the novel finding that RIARDS is characterized by lower concentrations of plasma biomarkers of inflammation compared to persistent ARDS, and that hypoinflammatory ARDS is more prevalent among patients with RIARDS. Identification and exclusion of RIARDS could potentially improve prognostic and predictive enrichment in clinical trials.

Plasma TNFRSF11B as a New Predictive Inflammatory Marker of Sepsis-ARDS with Endothelial Dysfunction

Inflammation plays an important role in the development of sepsis-acute respiratory distress syndrome (ARDS). Olink inflammation-related biomarker panels were used to analyze the levels of 92 inflammation-related proteins in plasma with sepsis-ARDS (n = 25) and healthy subjects (n = 25). There were significant differences in 64 inflammatory factors, including TNFRSF11B in sepsis-ARDS, which was significantly higher than that in controls. Functional analysis showed that TNFRSF11B was closely focused on signal transduction, immune response, and inflammatory response. The TNFRSF11B level in sepsis-ARDS plasma, LPS-induced mice, and LPS-stimulated HUVECs significantly increased. The highest plasma concentration of TNFRSF11B in patients with sepsis-ARDS was 10-20 ng/mL, and 10 ng/mL was selected to stimulate HUVECs. Western blot results demonstrated that the levels of syndecan-1, claudin-5, VE-cadherin, occludin, aquaporin-1, and caveolin-1 in TNFRSF11B-stimulated HUVECs decreased, whereas that of connexin-43 increased in TNFRSF11B-stimulated HUVECs. To the best of the authors' knowledge, this study was the first to reveal elevated TNFRSF11B in sepsis-ARDS associated with vascular endothelial dysfunction. In summary, TNFRSF11B may be a new potential predictive and diagnostic biomarker for vascular endothelium damage in sepsis-ARDS.

Red Cell Distribution Width at Admission Predicts the Frequency of Acute Kidney Injury and 28-Day Mortality in Patients With Acute Respiratory Distress Syndrome

OBJECTIVES

To determine the association of red cell distribution width (RDW) at admission with frequency of acute kidney injury (AKI) and 28-day mortality in acute respiratory distress syndrome (ARDS) patients.

METHODS

Two hundred fifty-eight ARDS patients were investigated in retrospective and prospective studies. The primary outcome was frequency of AKI. The secondary outcome was 28-day mortality.

RESULTS

The retrospective study included 193 ARDS patients, of which 67 (34.7%) were confirmed AKI and 76 (39.4%) died within 28 days. The RDW level in the AKI group was significantly higher than in the non-AKI group ([15.15 ± 2.59]% vs. [13.95 ± 1.89]%). Increased RDW was a significant predictor of frequency of AKI (odds ratio: 1.247, 95% confidence interval [CI]: 1.044, 1.489). The area under the receiver operating characteristic curve of RDW for predicting AKI was 0.687 (95%CI: 0.610, 0.764) and the cut-off value was 14.45 (sensitivity, 56.7%; specificity, 72.8%). In addition, the proportion of patients with RDW ≥ 14.45% in the non-survival group was notably higher compared with the survival group (48.7% vs. 29.1%). Furthermore, cox regression analysis revealed that RDW ≥ 14.45% was associated with 28-day mortality (hazard ratio: 1.817, 95%CI: 1.046, 3.158), while Kaplan-Meier analysis showed patients with RDW ≥ 14.45% had a significantly lower survival rate than those with RDW < 14.45%. The prospective study, on the other hand, included 65 ARDS patients, with frequency of AKI and 28-day mortality in the RDW ≥ 14.45% group significantly higher than in RDW < 14.45%.

CONCLUSION

RDW was a significant, independent predictor for frequency of AKI and 28-day mortality in ARDS patients.

Clinical Factors Influencing Endogenous Carbon Monoxide Production and Carboxyhemoglobin Levels in Neonates

Carboxyhemoglobin (COHb) is an index of endogenous carbon monoxide formation during the hem degradation process and could be used to confirm hemolysis in neonates. The influence of other clinical factors on COHb values in neonates has not been fully investigated. We aimed to evaluate the influence of hemolysis, sepsis, respiratory distress, and postnatal age on COHb values. We retrospectively analyzed COHb measurements determined with a carbon monoxide-oximeter in 4 groups of term neonates: A-sepsis, B-respiratory distress, C-hemolysis, and D-healthy neonates. The mean COHb values were 1.41% (SD: 0.26), 1.32% (SD: 0.27), 2.5% (SD: 0.69), and 1.27% (SD: 0.19) (P<0.001) in groups A (n=8), B (n=37), C (n=16), and D (n=76), respectively. COHb in group C was significantly higher than in the other groups. There was a negative correlation between postnatal age and COHb in healthy neonates. A cut-off level of 1.7% had 93% (95% confidence interval [CI]: 89%-97%) sensitivity and 94% (95% CI: 90%-98%) specificity for diagnosis of hemolysis. COHb values were higher during the first days of life. We found that COHb levels in neonates with hemolysis were significantly higher and that the influence of sepsis and respiratory distress on COHb values was insignificant.

Elevated Plasma Levels of Matrix Metalloproteinase-3 and Tissue-Inhibitor of Matrix Metalloproteinases-1 Associate With Organ Dysfunction and Mortality in Sepsis

BACKGROUND

Matrix Metalloproteinases (MMP) respond to tissue damage during sepsis. Higher plasma concentrations of MMPs and the tissue-inhibitor of matrix metalloproteinases (TIMP) have been reported in sepsis compared with healthy controls. The objective of this study was to examine if plasma levels of MMP-3, MMP-9, and TIMP-1 associate with mortality and organ dysfunction during sepsis.

METHODS

We conducted a prospective cohort study of critically ill patients with sepsis adjudicated per Sepsis-3 criteria at a tertiary academic medical center. We measured plasma concentrations of MMP-3, MMP-9, and TIMP-1 on intensive care unit admission. We phenotyped the subjects for shock, acute respiratory distress syndrome (ARDS), acute kidney injury (AKI), and mortality at 30 days. We used logistic regression to test the associations between the MMPs and TIMP-1 with shock, ARDS, AKI, and mortality.

RESULTS

Higher plasma TIMP-1 levels were associated with shock (odds ratio [OR] 1.51 per log increase [95% CI 1.25, 1.83]), ARDS (OR 1.24 [95% CI 1.05, 1.46]), AKI (OR 1.18 [95% CI 1.01, 1.38]), and mortality (OR 1.20 [95% CI 1.05, 1.46]. Higher plasma MMP-3 concentrations were associated with shock (OR 1.40 [95% CI 1.12, 1.75]) and mortality (OR 1.24 [95% CI 1.03, 1.48]) whereas MMP-9 levels were not associated with outcomes. Higher plasma TIMP-1 to MMP-3 ratios were associated with shock (OR 1.41 [95% CI 1.15, 1.72], P = 0.02).

CONCLUSION

Elevated plasma concentrations of TIMP-1 associate with organ dysfunction and mortality in sepsis. Higher plasma levels of MMP-3 associate with shock and mortality. Plasma MMP and TIMP-1 may warrant further investigation as emerging sepsis theragnostic biomarkers.

Predicting respiratory failure in patients infected by SARS-CoV-2 by admission sex-specific biomarkers

BACKGROUND

Several biomarkers have been identified to predict the outcome of COVID-19 severity, but few data are available regarding sex differences in their predictive role. Aim of this study was to identify sex-specific biomarkers of severity and progression of acute respiratory distress syndrome (ARDS) in COVID-19.

METHODS

Plasma levels of sex hormones (testosterone and 17β-estradiol), sex-hormone dependent circulating molecules (ACE2 and Angiotensin1-7) and other known biomarkers for COVID-19 severity were measured in male and female COVID-19 patients at admission to hospital. The association of plasma biomarker levels with ARDS severity at admission and with the occurrence of respiratory deterioration during hospitalization was analysed in aggregated and sex disaggregated form.

RESULTS

Our data show that some biomarkers could be predictive both for males and female patients and others only for one sex. Angiotensin1-7 plasma levels and neutrophil count predicted the outcome of ARDS only in females, whereas testosterone plasma levels and lymphocytes counts only in males.

CONCLUSIONS

Sex is a biological variable affecting the choice of the correct biomarker that might predict worsening of COVID-19 to severe respiratory failure. The definition of sex specific biomarkers can be useful to alert patients to be safely discharged versus those who need respiratory monitoring.

Andrographolide sulfonate attenuates alveolar hypercoagulation and fibrinolytic inhibition partly via NF-κB pathway in LPS-induced acute respiratory distress syndrome in mice

BACKGROUND

Alveolar hypercoagulation and fibrinolytic inhibition are important characteristics during acute respiratory distress syndrome (ARDS), and NF-κB p65 signaling pathway is involved to regulate these pathophysiologies. We hypothesize that targeting NF-κB signal pathway could ameliorate alveolar hypercoagulation and fibrinolyitc inhibition, thus attenuating lung injury in ARDS.

PURPOSE

We explore the efficacy and the potential mechanism of andrographolide sulfonate (Andro-S) on alveolar hypercoagulation and fibrinolytic inhibition in LPS-induced ARDS in mice.

METHODS

ARDS was made by lipopolysaccharide (LPS) inhalation in C57BLmice. Andrographolide sulfonate (2.5, 5 and 10 mg/kg) was intraperitoneally given to the mice (once a day for three consecutive days) before LPS administration. NEMO binding domain peptide (NBD), an inhibitor of NF-κB, was used as the positive control and it replaced Andro-S in mice of NBD group. Mice in normal control received saline instead of LPS. Lung tissues and bronchoalveolar lavage fluid (BALF) were collected for analysis of alveolar coagulation, fibrinolytic inhibition as well as of pulmonary inflammatory response after 8 h of LPS inhalation. NF-κB signal pathway in lung tissue was simultaneously determined.

RESULTS

Andro-S dose-dependently inhibited tissue factor (TF) and plasminogen activator inhibitor (PAI)-1 expressions either in mRNA or in protein in lung tissue of ARDS mice, and it also decreased the concentrations of TF, PAI-1, thrombin-antithrombin complex (TAT), procollagen peptide type Ⅲ (PⅢP) while promoting the production of activated protein C (APC) in BALF. Meanwhile, Andro-S effectively inhibited inflammatory response (interleukin 1β and myeloperoxidase) induced by LPS. LPS stimulation dramatically activated NF-κB signal pathway, indicated by increased expressions of phosphorylation of p65 (p-p65), p-IKKα/β and p-IκBα and the higher p65-DNA binding activity, which were all dose-dependently reversed by Andro-S. Andro-S and NBD presented similar efficacies.

CONCLUSIONS

Andro-S treatment improves alveolar hypercoagulation and fibrinolytic inhibition and attenuates pulmonary inflammation in LPS-induced ARDS in mice partly through NF-κB pathway inactivation. The drug is expected to be an effective choice for ARDS.

Inferring a causal relationship between ceramide levels and COVID-19 respiratory distress

A causal relationship between plasma ceramide concentration and respiratory distress symptoms in COVID-19 patients is inferred. In this study, plasma samples of 52 individuals infected with COVID-19 were utilized in a lipidomic analysis. Lipids belonging to the ceramide class exhibited a 400-fold increase in total plasma concentration in infected patients. Further analysis led to the demonstration of concentration dependency for severe COVID-19 respiratory symptoms in a subclass of ceramides. The subclasses Cer(d18:0/24:1), Cer(d18:1/24:1), and Cer(d18:1/22:0) were shown to be increased by 48-, 40-, and 33-fold, respectively, in infected plasma samples and to 116-, 91- and 50-fold, respectively, in plasma samples with respiratory distress. Hence, monitoring plasma ceramide concentration, can be a valuable tool for measuring effects of therapies on COVID-19 respiratory distress patients.

Commonalities Between ARDS, Pulmonary Fibrosis and COVID-19: The Potential of Autotaxin as a Therapeutic Target

Severe COVID-19 is characterized by acute respiratory distress syndrome (ARDS)-like hyperinflammation and endothelial dysfunction, that can lead to respiratory and multi organ failure and death. Interstitial lung diseases (ILD) and pulmonary fibrosis confer an increased risk for severe disease, while a subset of COVID-19-related ARDS surviving patients will develop a fibroproliferative response that can persist post hospitalization. Autotaxin (ATX) is a secreted lysophospholipase D, largely responsible for the extracellular production of lysophosphatidic acid (LPA), a pleiotropic signaling lysophospholipid with multiple effects in pulmonary and immune cells. In this review, we discuss the similarities of COVID-19, ARDS and ILDs, and suggest ATX as a possible pathologic link and a potential common therapeutic target.

Characterizing preclinical sub-phenotypic models of acute respiratory distress syndrome: An experimental ovine study

The acute respiratory distress syndrome (ARDS) describes a heterogenous population of patients with acute severe respiratory failure. However, contemporary advances have begun to identify distinct sub-phenotypes that exist within its broader envelope. These sub-phenotypes have varied outcomes and respond differently to several previously studied interventions. A more precise understanding of their pathobiology and an ability to prospectively identify them, may allow for the development of precision therapies in ARDS. Historically, animal models have played a key role in translational research, although few studies have so far assessed either the ability of animal models to replicate these sub-phenotypes or investigated the presence of sub-phenotypes within animal models. Here, in three ovine models of ARDS, using combinations of oleic acid and intravenous, or intratracheal lipopolysaccharide, we investigated the presence of sub-phenotypes which qualitatively resemble those found in clinical cohorts. Principal Component Analysis and partitional clustering identified two clusters, differentiated by markers of shock, inflammation, and lung injury. This study provides a first exploration of ARDS phenotypes in preclinical models and suggests a methodology for investigating this phenomenon in future studies.

Serum CD5L predicts acute lung parenchymal injury and acute respiratory distress syndrome in trauma patients

Cluster of differentiation 5 antigen-like (CD5L), derived from alveolar epithelial cells partly, is a secreted protein. It is shown that CD5L is associated with lung inflammation and systemic inflammatory diseases, but the relationship between CD5L and trauma-related acute lung parenchymal injury (PLI), acute lung injury or acute respiratory distress syndrome (ARDS) is unclear. This study aims to explore the value of serum CD5L levels in predicting trauma-associated PLI/ARDS and its potential clinical significance.This is a prospective observational study, and a total of 127 trauma patients were recruited from the emergency department (ED), and among them, 81 suffered from PLI/ARDS within 24 hours after trauma, and 46 suffered from trauma without PLI/ARDS. Fifty healthy subjects from the medical examination center were also recruited as controls for comparison. The serum CD5L level was measured within 24 hours of admission. The receiver operating characteristic analysis and logistic regression analysis were used to identify the correlation between high CD5L and trauma associated-PLI/ARDS within 24 hours following trauma.The trauma associated-PLI/ARDS subjects showed a significantly higher level of serum CD5L on emergency department admission within 24 hours after trauma compared with its level in non-trauma associated-PLI/ARDS subjects and healthy subjects. The initial CD5L concentration higher than 150.3 ng/mL was identified as indicating a high risk of PLI/ARDS within 24 hours following trauma (95% confidence interval: 0.674-0.878; P < .001). Moreover, CD5L was an independent risk factor for trauma associated-PLI/ARDS within 24 hours following trauma.CD5L could predict PLI/ARDS within 24 hours following trauma.

eARDS: A multi-center validation of an interpretable machine learning algorithm of early onset Acute Respiratory Distress Syndrome (ARDS) among critically ill adults with COVID-19

We present an interpretable machine learning algorithm called ‘eARDS’ for predicting ARDS in an ICU population comprising COVID-19 patients, up to 12-hours before satisfying the Berlin clinical criteria. The analysis was conducted on data collected from the Intensive care units (ICU) at Emory Healthcare, Atlanta, GA and University of Tennessee Health Science Center, Memphis, TN and the Cerner^® Health Facts Deidentified Database, a multi-site COVID-19 EMR database. The participants in the analysis consisted of adults over 18 years of age. Clinical data from 35,804 patients who developed ARDS and controls were used to generate predictive models that identify risk for ARDS onset up to 12-hours before satisfying the Berlin criteria. We identified salient features from the electronic medical record that predicted respiratory failure among this population. The machine learning algorithm which provided the best performance exhibited AUROC of 0.89 (95% CI = 0.88–0.90), sensitivity of 0.77 (95% CI = 0.75–0.78), specificity 0.85 (95% CI = 085–0.86). Validation performance across two separate health systems (comprising 899 COVID-19 patients) exhibited AUROC of 0.82 (0.81–0.83) and 0.89 (0.87, 0.90). Important features for prediction of ARDS included minimum oxygen saturation (SpO₂), standard deviation of the systolic blood pressure (SBP), O₂ flow, and maximum respiratory rate over an observational window of 16-hours. Analyzing the performance of the model across various cohorts indicates that the model performed best among a younger age group (18–40) (AUROC = 0.93 [0.92–0.94]), compared to an older age group (80+) (AUROC = 0.81 [0.81–0.82]). The model performance was comparable on both male and female groups, but performed significantly better on the severe ARDS group compared to the mild and moderate groups. The eARDS system demonstrated robust performance for predicting COVID19 patients who developed ARDS at least 12-hours before the Berlin clinical criteria, across two independent health systems.

Cytokine signatures of end organ injury in COVID-19

Increasing evidence has shown that Coronavirus disease 19 (COVID-19) severity is driven by a dysregulated immunologic response. We aimed to assess the differences in inflammatory cytokines in COVID-19 patients compared to contemporaneously hospitalized controls and then analyze the relationship between these cytokines and the development of Acute Respiratory Distress Syndrome (ARDS), Acute Kidney Injury (AKI) and mortality. In this cohort study of hospitalized patients, done between March third, 2020 and April first, 2020 at a quaternary referral center in New York City we included adult hospitalized patients with COVID-19 and negative controls. Serum specimens were obtained on the first, second, and third hospital day and cytokines were measured by Luminex. Autopsies of nine cohort patients were examined. We identified 90 COVID-19 patients and 51 controls. Analysis of 48 inflammatory cytokines revealed upregulation of macrophage induced chemokines, T-cell related interleukines and stromal cell producing cytokines in COVID-19 patients compared to the controls. Moreover, distinctive cytokine signatures predicted the development of ARDS, AKI and mortality in COVID-19 patients. Specifically, macrophage-associated cytokines predicted ARDS, T cell immunity related cytokines predicted AKI and mortality was associated with cytokines of activated immune pathways, of which IL-13 was universally correlated with ARDS, AKI and mortality. Histopathological examination of the autopsies showed diffuse alveolar damage with significant mononuclear inflammatory cell infiltration. Additionally, the kidneys demonstrated glomerular sclerosis, tubulointerstitial lymphocyte infiltration and cortical and medullary atrophy. These patterns of cytokine expression offer insight into the pathogenesis of COVID-19 disease, its severity, and subsequent lung and kidney injury suggesting more targeted treatment strategies.

Type 1 inflammatory endotype relates to low compliance, lung fibrosis, and severe complications in COVID-19

Background

Coronavirus disease 2019 (COVID-19) is an acute respiratory disease; approximately 5% of patients developing severe COVID-19. It is known that cytokine release is associated with disease severity, but the relationship between the different clinical phenotypes and inflammatory endotypes is not well understood.

Objective

This study investigated the association between inflammatory biomarker-based endotypes and severe COVID-19 phenotypes.

Methods

Interleukin (IL) -6, C-reactive protein (CRP), C–X–C motif chemokine (CXCL) 9, IL-18, C–C motif chemokine (CCL) 3, CCL17, IL-10, and vascular endothelial growth factor (VEGF) were measured in 57 COVID-19 patients, and their association with clinical characteristics was examined using a cluster analysis.

Results

Significantly higher blood levels of the eight inflammatory markers were noted in patients who developed acute respiratory distress syndrome (ARDS) than in those who did not develop ARDS (non-ARDS). Using a cluster analysis, the patient groups were classified into four clusters, of which two had patients with high IL-6 and CRP levels. In the cluster with high levels of Type 1 (T1) inflammatory markers such as CXCL9 and IL-18, 85% of the patients had ARDS, 65% of the patients developed acute kidney injury (AKI), and 78% of the patients developed pulmonary fibrosis.

Conclusions

In the cluster with high levels of T1 inflammatory markers, the patients frequently suffered from tissue damage, manifested as ARDS and AKI. Our findings identified distinct T1 inflammatory endotypes of COVID-19 and suggest the importance of controlling inflammation by monitoring T1 biomarkers and treating accordingly to limit the severity of the disease.

SARS-CoV-2 antibody immunoassays in serial samples reveal earlier seroconversion in acutely ill COVID-19 patients developing ARDS

OBJECTIVES

During the COVID-19 pandemic, SARS-CoV-2 antibody testing has been suggested for (1) screening populations for disease prevalence, (2) diagnostics, and (3) guiding therapeutic applications. Here, we conducted a detailed clinical evaluation of four Anti-SARS-CoV-2 immunoassays in samples from acutely ill COVID-19 patients and in two negative cohorts.

METHODS

443 serum specimens from serial sampling of 29 COVID-19 patients were used to determine clinical sensitivities. Patients were stratified for the presence of acute respiratory distress syndrome (ARDS). Individual serum specimens from a pre-COVID-19 cohort of 238 healthy subjects and from a PCR-negative clinical cohort of 257 patients were used to determine clinical specificities. All samples were measured side-by-side with the Anti-SARS-CoV-2-ELISA (IgG), Anti-SARS-CoV-2-ELISA (IgA) and Anti-SARS-CoV-2-NCP-ELISA (IgG) (Euroimmun AG, Lübeck, Germany) and the Elecsys Anti-SARS-CoV-2 ECLIA (Roche Diagnostics International, Rotkreuz, Switzerland).

RESULTS

Median seroconversion occurred earlier in ARDS patients (8-9 days) than in non-ARDS patients (11-17 days), except for EUR N-IgG. Rates of positivity and mean signal ratios in the ARDS group were significantly higher than in the non-ARDS group. Sensitivities between the four tested immunoassays were equivalent. In the set of negative samples, the specificity of the Anti-SARS-CoV-2-ELISA (IgA) was lower (93.9%) compared to all other assays (≥98.8%) and the specificity of Anti-SARS-CoV-2-NCP-ELISA (IgG) was lower (98.8%) than that of Elecsys Anti-SARS-CoV-2 (100%).

CONCLUSIONS

Serial sampling in COVID-19 patients revealed earlier seroconversion and higher signal ratios of SARS-CoV-2 antibodies as a potential risk marker for the development of ARDS, suggesting a utility for antibody testing in acutely diseased patients.

The prognostic role of hyperglycemia and glucose variability in covid-related acute respiratory distress Syndrome

AIMS

Due to heterogeneity on the prognostic role of glucose values and glucose variability in Novel Coronavirus (COVID) disease, we aimed at assessing the prognostic role for Intensive Care Unit (ICU) death of admission hyperglycaemia, peak glycemia and glucose variability in critically ill COVID patients: METHODS: 83 patients consecutively admitted for COVID-related Acute Respiratory Distress Syndrome (ARDS) from from 1st March to 1st October 2020.

RESULTS

Non survivors were older, with more comorbidities and a more severe disease. Corticosteroids were used in the majority of patients (54/83, 65%) with no difference between survivors and non survivors. Mean blood glucose values, (during the first 24 and 48 h, respectively), were comparable between the two subgroups, as well as SD 24 and CV 24. During the first 48 h, survivors showed significantly lower values of SD 48 (p < 0.001) and CV 48, respectively (p < 0.001) than non survivors.

CONCLUSIONS

in consecutive COVID-related ARDS patients admitted to ICU hyperglycemia (>180 mg/dl) is more common in non survivors who also showed a significantly higher glucose variability in the first 48 h since ICU admission. Our findings point to the clinical significance of in-ICU glucose control in severe COVID patients.

Lower or Higher Oxygenation Targets for Acute Hypoxemic Respiratory Failure

BACKGROUND

Patients with acute hypoxemic respiratory failure in the intensive care unit (ICU) are treated with supplemental oxygen, but the benefits and harms of different oxygenation targets are unclear. We hypothesized that using a lower target for partial pressure of arterial oxygen (Pao₂) would result in lower mortality than using a higher target.

METHODS

In this multicenter trial, we randomly assigned 2928 adult patients who had recently been admitted to the ICU (≤12 hours before randomization) and who were receiving at least 10 liters of oxygen per minute in an open system or had a fraction of inspired oxygen of at least 0.50 in a closed system to receive oxygen therapy targeting a Pao₂ of either 60 mm Hg (lower-oxygenation group) or 90 mm Hg (higher-oxygenation group) for a maximum of 90 days. The primary outcome was death within 90 days.

RESULTS

At 90 days, 618 of 1441 patients (42.9%) in the lower-oxygenation group and 613 of 1447 patients (42.4%) in the higher-oxygenation group had died (adjusted risk ratio, 1.02; 95% confidence interval, 0.94 to 1.11; P = 0.64). At 90 days, there was no significant between-group difference in the percentage of days that patients were alive without life support or in the percentage of days they were alive after hospital discharge. The percentages of patients who had new episodes of shock, myocardial ischemia, ischemic stroke, or intestinal ischemia were similar in the two groups (P = 0.24).

CONCLUSIONS

Among adult patients with acute hypoxemic respiratory failure in the ICU, a lower oxygenation target did not result in lower mortality than a higher target at 90 days. (Funded by the Innovation Fund Denmark and others; HOT-ICU ClinicalTrials.gov number, NCT03174002.).

The Role of Immunological and Clinical Biomarkers to Predict Clinical COVID-19 Severity and Response to Therapy-A Prospective Longitudinal Study

Background

The association of pro-inflammatory markers such as interleukin-6 (IL-6) and other biomarkers with severe coronavirus disease 2019 (COVID-19) is of increasing interest, however their kinetics, response to current COVID-related treatments, association with disease severity and comparison with other disease states associated with potential cytokine storm (CS) such as Staphylococcus aureus bacteraemia (SAB) are ill-defined.

Methods

A cohort of 55 hospitalized SARS-CoV-2 positive patients was prospectively recruited - blood sampling was performed at baseline, post-treatment and hospital discharge. Serum IL-6, C-reactive protein (CRP) and other laboratory investigations were compared between treatment groups and across timepoints. Acute serum IL-6 and CRP levels were then compared to those with suspected COVID-19 (SCOVID) and age and sex matched patients with SAB and patients hospitalized for any non-infectious condition (NIC).

Results

IL-6 was elevated at admission in the SARS-CoV-2 cohort but at lower levels compared to matched SAB patients. Median (IQR) IL-6 at admission was 73.89 pg/mL (30.9, 126.39) in SARS-CoV-2 compared to 92.76 pg/mL (21.75, 246.55) in SAB (p=0.017); 12.50 pg/mL (3.06, 35.77) in patients with NIC; and 95.51 pg/mL (52.17, 756.67) in SCOVID. Median IL-6 and CRP levels decreased between admission and discharge timepoints. This reduction was amplified in patients treated with remdesivir and/or dexamethasone. CRP and bedside vital signs were the strongest predictors of COVID-19 severity.

Conclusions

Knowledge of the kinetics of IL-6 did not offer enhanced predictive value for disease severity in COVID-19 over common investigations such as CRP and vital signs.

Biological subphenotypes of acute respiratory distress syndrome may not reflect differences in alveolar inflammation

Biological subphenotypes have been identified in acute respiratory distress syndrome (ARDS) based on two parsimonious models: the "uninflamed" and "reactive" subphenotype (cluster-model) and "hypo-inflammatory" and "hyper-inflammatory" (latent class analysis (LCA) model). The distinction between the subphenotypes is mainly driven by inflammatory and coagulation markers in plasma. However, systemic inflammation is not specific for ARDS and it is unknown whether these subphenotypes also reflect differences in the alveolar compartment. Alveolar inflammation and dysbiosis of the lung microbiome have shown to be important mediators in the development of lung injury. This study aimed to determine whether the "reactive" or "hyper-inflammatory" biological subphenotype also had higher concentrations of inflammatory mediators and enrichment of gut-associated bacteria in the lung. Levels of alveolar inflammatory mediators myeloperoxidase (MPO), surfactant protein D (SPD), interleukin (IL)-1b, IL-6, IL-10, IL-8, interferon gamma (IFN-ƴ), and tumor necrosis factor-alpha (TNFα) were determined in the mini-BAL fluid. Key features of the lung microbiome were measured: bacterial burden (16S rRNA gene copies/ml), community diversity (Shannon Diversity Index), and community composition. No statistically significant differences between the "uninflamed" and "reactive" ARDS subphenotypes were found in a selected set of alveolar inflammatory mediators and key features of the lung microbiome. LCA-derived subphenotypes and stratification based on cause of ARDS (direct vs. indirect) showed similar profiles, suggesting that current subphenotypes may not reflect the alveolar host response. It is important for future research to elucidate the pulmonary biology within each subphenotype properly, which is arguably a target for intervention.

The risk factors for acute respiratory distress syndrome in patients with severe acute pancreatitis: A retrospective analysis

Acute respiratory distress syndrome (ARDS) is very common in patients with severe acute pancreatitis (SAP), the early interventions are essential to the prognosis of SAP patients. We aimed to evaluate the risk factors for ARDS in SAP patients, to provide insights into the management of SAP.SAP patients treated in our hospital from June 1, 2018 to May 31, 2020 were included. The characteristics and lab test results were collected and compared, and we conducted the logistic regression analyses were conducted to identify the potential risk factors for ARDS in patients with SAP.A total of 281 SAP patients were included finally, the incidence of ARDS in patients with SAP was 30.60%. There were significant differences on the respiratory rate, heart rate, APACHE II and Ranson score between 2 groups (all P < .05). And there were significant differences on the polymorphonuclear, procalcitonin, C-reactive protein, serum creatinine, albumin and PO2/FiO2 between 2 groups (all P < .05), and no significant differences on the K+, Na+, Ca+, white blood cell, neutrophils, urine and blood amylase, trypsin, lipase, alanine aminotransferase, aspartate aminotransferase, total bilirubin, triglyceride, total cholesterol, total bilirubin, fasting blood glucose, and pH were found (all P > .05). Respiratory rate >30/min (odds ratio [OR]: 2.405, 95% confidence interval[CI]: 1.163-4.642), APACHE II score >11 (OR: 1.639, 95% CI: 1.078-2.454), Ranson score >5 (OR: 1.473, 95% CI: 1.145-2.359), polymorphonuclear >14 × 109/L (OR: 1.316, 95% CI: 1.073-2.328), C-reactive protein >150 mg/L (OR: 1.127, 95% CI: 1.002-1.534), albumin ≤30 g/L (OR: 1.113, 95% CI: 1.005-1.489) were the independent risk factors for ARDS in patients with SAP (all P < .05).The incidence of ARDS in SAP patients is relatively high, and it is necessary to carry out targeted early prevention and treatment for the above risk factors.

The ABO histo-blood group, endothelial activation, and acute respiratory distress syndrome risk in critical illness

BACKGROUNDThe ABO histo-blood group is defined by carbohydrate modifications and is associated with risk for multiple diseases, including acute respiratory distress syndrome (ARDS). We hypothesized that genetically determined blood subtype A1 is associated with increased risk of ARDS and markers of microvascular dysfunction and coagulation.METHODSWe conducted analyses in 3 cohorts of critically ill trauma and sepsis patients (n = 3710) genotyped on genome-wide platforms to determine the association of the A1 blood type genotype with ARDS risk. We subsequently determined whether associations were present in FUT2-defined nonsecretors who lack ABO antigens on epithelium, but not endothelium. In a patient subgroup, we determined the associations of blood type with plasma levels of endothelial glycoproteins and disseminated intravascular coagulation (DIC). Lastly, we tested whether blood type A was associated with less donor lung injury recovery during human ex vivo lung perfusion (EVLP).RESULTSThe A1 genotype was associated with a higher risk of moderate to severe ARDS relative to type O in all 3 populations. In sepsis, this relationship was strongest in nonpulmonary infections. The association persisted in nonsecretors, suggesting a vascular mechanism. The A1 genotype was also associated with higher DIC risk as well as concentrations of thrombomodulin and von Willebrand factor, which in turn were associated with ARDS risk. Blood type A was also associated with less lung injury recovery during EVLP.CONCLUSIONWe identified a replicable association between ABO blood type A1 and risk of ARDS among the critically ill, possibly mediated through microvascular dysfunction and coagulation.FUNDINGNIH HL122075, HL125723, HL137006, HL137915, DK097307, HL115354, HL101779, and the University of Pennsylvania McCabe Fund Fellowship Award.

Characterisation and outcomes of ARDS secondary to pneumonia in patients with and without SARS-CoV-2: a single-centre experience

Introduction

Acute respiratory distress syndrome (ARDS) is the major cause of mortality in patients with SARS-CoV-2 pneumonia. It appears that development of ‘cytokine storm’ in patients with SARS-CoV-2 pneumonia precipitates progression to ARDS. However, severity scores on admission do not predict severity or mortality in patients with SARS-CoV-2 pneumonia. Our objective was to determine whether patients with SARS-CoV-2 ARDS are clinically distinct, therefore requiring alternative management strategies, compared with other patients with ARDS. We report a single-centre retrospective study comparing the characteristics and outcomes of patients with ARDS with and without SARS-CoV-2.

Methods

Two intensive care unit (ICU) cohorts of patients at the Queen Elizabeth Hospital Birmingham were analysed: SARS-CoV-2 patients admitted between 11 March and 21 April 2020 and all patients with community-acquired pneumonia (CAP) from bacterial or viral infection who developed ARDS between 1 January 2017 and 1 November 2019. All data were routinely collected on the hospital’s electronic patient records.

Results

A greater proportion of SARS-CoV-2 patients were from an Asian ethnic group (p=0.002). SARS-CoV-2 patients had lower circulating leucocytes, neutrophils and monocytes (p<0.0001), but higher CRP (p=0.016) on ICU admission. SARS-CoV-2 patients required a longer duration of mechanical ventilation (p=0.01), but had lower vasopressor requirements (p=0.016).

Discussion

The clinical syndromes and respiratory mechanics of SARS-CoV-2 and CAP-ARDS are broadly similar. However, SARS-CoV-2 patients initially have a lower requirement for vasopressor support, fewer circulating leukocytes and require prolonged ventilation support. Further studies are required to determine whether the dysregulated inflammation observed in SARS-CoV-2 ARDS may contribute to the increased duration of respiratory failure.

Colchicine reduces lung injury in experimental acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is characterized by intense dysregulated inflammation leading to acute lung injury (ALI) and respiratory failure. There are no effective pharmacologic therapies for ARDS. Colchicine is a low-cost, widely available drug, effective in the treatment of inflammatory conditions. We studied the effects of colchicine pre-treatment on oleic acid-induced ARDS in rats. Rats were treated with colchicine (1 mg/kg) or placebo for three days prior to intravenous oleic acid-induced ALI (150 mg/kg). Four hours later they were studied and compared to a sham group. Colchicine reduced the area of histological lung injury by 61%, reduced lung edema, and markedly improved oxygenation by increasing PaO2/FiO2 from 66 ± 13 mmHg (mean ± SEM) to 246 ± 45 mmHg compared to 380 ± 18 mmHg in sham animals. Colchicine also reduced PaCO2 and respiratory acidosis. Lung neutrophil recruitment, assessed by myeloperoxidase immunostaining, was greatly increased after injury from 1.16 ± 0.19% to 8.86 ± 0.66% and significantly reduced by colchicine to 5.95 ± 1.13%. Increased lung NETosis was also reduced by therapy. Circulating leukocytosis after ALI was not reduced by colchicine therapy, but neutrophils reactivity and CD4 and CD8 cell surface expression on lymphocyte populations were restored. Colchicine reduces ALI and respiratory failure in experimental ARDS in relation with reduced lung neutrophil recruitment and reduced circulating leukocyte activation. This study supports the clinical development of colchicine for the prevention of ARDS in conditions causing ALI.

Uncontrolled Innate and Impaired Adaptive Immune Responses in Patients with COVID-19 Acute Respiratory Distress Syndrome

Rationale: Uncontrolled inflammatory innate response and impaired adaptive immune response are associated with clinical severity in patients with coronavirus disease (COVID-19).Objectives: To compare the immunopathology of COVID-19 acute respiratory distress syndrome (ARDS) with that of non-COVID-19 ARDS, and to identify biomarkers associated with mortality in patients with COVID-19 ARDS.Methods: Prospective observational monocenter study. Immunocompetent patients diagnosed with RT-PCR-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and ARDS admitted between March 8 and March 30, 2020, were included and compared with patients with non-COVID-19 ARDS. The primary clinical endpoint of the study was mortality at Day 28. Flow cytometry analyses and serum cytokine measurements were performed at Days 1-2 and 4-6 of ICU admission.Measurements and Main Results: As compared with patients with non-COVID-19 ARDS (n = 36), those with COVID-19 (n = 38) were not significantly different regarding age, sex, and Sequential Organ Failure Assessment and Simplified Acute Physiology Score II scores but exhibited a higher Day-28 mortality (34% vs. 11%, P = 0.030). Patients with COVID-19 showed profound and sustained T CD4+ (P = 0.002), CD8+ (P < 0.0001), and B (P < 0.0001) lymphopenia, higher HLA-DR expression on monocytes (P < 0.001) and higher serum concentrations of EGF (epithelial growth factor), GM-CSF, IL-10, CCL2/MCP-1, CCL3/MIP-1a, CXCL10/IP-10, CCL5/RANTES, and CCL20/MIP-3a. After adjusting on age and Sequential Organ Failure Assessment, serum CXCL10/IP-10 (P = 0.047) and GM-CSF (P = 0.050) were higher and nasopharyngeal RT-PCR cycle threshold values lower (P = 0.010) in patients with COVID-19 who were dead at Day 28.Conclusions: Profound global lymphopenia and a "chemokine signature" were observed in COVID-19 ARDS. Increased serum concentrations of CXCL10/IP-10 and GM-CSF, together with higher nasopharyngeal SARS-CoV-2 viral load, were associated with Day-28 mortality.

Higher procoagulatory potential but lower DIC score in COVID-19 ARDS patients compared to non-COVID-19 ARDS patients

BACKGROUND

COVID-19 is a novel viral disease. Severe courses may present as ARDS. Several publications report a high incidence of coagulation abnormalities in these patients. We aimed to compare coagulation and inflammation parameters in patients with ARDS due to SARS-CoV-2 infection versus patients with ARDS due to other causes.

METHODS

This retrospective study included intubated patients admitted with the diagnosis of ARDS to the ICU at Munich university hospital. 22 patients had confirmed SARS-CoV2-infection (COVID-19 group), 14 patients had bacterial or other viral pneumonia (control group). Demographic, clinical parameters and laboratory tests including coagulation parameters and thromboelastometry were analysed.

RESULTS

No differences were found in gender ratios, BMI, Horovitz quotients and haemoglobin values. The median SOFA score, serum lactate levels, renal function parameters (creatinine, urea) and all inflammation markers (IL-6, PCT, CRP) were lower in the COVID-19 group (all: p < 0.05). INR (p < 0.001) and antithrombin (p < 0.001) were higher in COVID-19 patients. D-dimer levels (p = 0.004) and consecutively the DIC score (p = 0.003) were lower in this group. In ExTEM®, Time-to-Twenty (TT20) was shorter in the COVID-19 group (p = 0.047), these patients also had higher FibTEM® MCF (p = 0.005). Further, these patients presented with elevated antigen and activity levels of von-Willebrand-Factor (VWF).

CONCLUSION

COVID-19 patients presented with higher coagulatory potential (shortened global clotting tests, increased viscoelastic and VWF parameters), while DIC scores were lower. An intensified anticoagulation regimen based on an individual risk assessment is advisable to avoid thromboembolic complications.

Cytokine elevation in severe and critical COVID-19: a rapid systematic review, meta-analysis, and comparison with other inflammatory syndromes

The description of a so-called cytokine storm in patients with COVID-19 has prompted consideration of anti-cytokine therapies, particularly interleukin-6 antagonists. However, direct systematic comparisons of COVID-19 with other critical illnesses associated with elevated cytokine concentrations have not been reported. In this Rapid Review, we report the results of a systematic review and meta-analysis of COVID-19 studies published or posted as preprints between Nov 1, 2019, and April 14, 2020, in which interleukin-6 concentrations in patients with severe or critical disease were recorded. 25 COVID-19 studies (n=1245 patients) were ultimately included. Comparator groups included four trials each in sepsis (n=5320), cytokine release syndrome (n=72), and acute respiratory distress syndrome unrelated to COVID-19 (n=2767). In patients with severe or critical COVID-19, the pooled mean serum interleukin-6 concentration was 36·7 pg/mL (95% CI 21·6-62·3 pg/mL; I2=57·7%). Mean interleukin-6 concentrations were nearly 100 times higher in patients with cytokine release syndrome (3110·5 pg/mL, 632·3-15 302·9 pg/mL; p<0·0001), 27 times higher in patients with sepsis (983·6 pg/mL, 550·1-1758·4 pg/mL; p<0·0001), and 12 times higher in patients with acute respiratory distress syndrome unrelated to COVID-19 (460 pg/mL, 216·3-978·7 pg/mL; p<0·0001). Our findings question the role of a cytokine storm in COVID-19-induced organ dysfunction. Many questions remain about the immune features of COVID-19 and the potential role of anti-cytokine and immune-modulating treatments in patients with the disease.

Endothelial Damage in Acute Respiratory Distress Syndrome

The pulmonary endothelium is a metabolically active continuous monolayer of squamous endothelial cells that internally lines blood vessels and mediates key processes involved in lung homoeostasis. Many of these processes are disrupted in acute respiratory distress syndrome (ARDS), which is marked among others by diffuse endothelial injury, intense activation of the coagulation system and increased capillary permeability. Most commonly occurring in the setting of sepsis, ARDS is a devastating illness, associated with increased morbidity and mortality and no effective pharmacological treatment. Endothelial cell damage has an important role in the pathogenesis of ARDS and several biomarkers of endothelial damage have been tested in determining prognosis. By further understanding the endothelial pathobiology, development of endothelial-specific therapeutics might arise. In this review, we will discuss the underlying pathology of endothelial dysfunction leading to ARDS and emerging therapies. Furthermore, we will present a brief overview demonstrating that endotheliopathy is an important feature of hospitalised patients with coronavirus disease-19 (COVID-19).

Complement and tissue factor-enriched neutrophil extracellular traps are key drivers in COVID-19 immunothrombosis

Emerging data indicate that complement and neutrophils contribute to the maladaptive immune response that fuels hyperinflammation and thrombotic microangiopathy, thereby increasing coronavirus 2019 (COVID-19) mortality. Here, we investigated how complement interacts with the platelet/neutrophil extracellular traps (NETs)/thrombin axis, using COVID-19 specimens, cell-based inhibition studies, and NET/human aortic endothelial cell (HAEC) cocultures. Increased plasma levels of NETs, tissue factor (TF) activity, and sC5b-9 were detected in patients. Neutrophils of patients yielded high TF expression and released NETs carrying active TF. Treatment of control neutrophils with COVID-19 platelet-rich plasma generated TF-bearing NETs that induced thrombotic activity of HAECs. Thrombin or NETosis inhibition or C5aR1 blockade attenuated platelet-mediated NET-driven thrombogenicity. COVID-19 serum induced complement activation in vitro, consistent with high complement activity in clinical samples. Complement C3 inhibition with compstatin Cp40 disrupted TF expression in neutrophils. In conclusion, we provide a mechanistic basis for a pivotal role of complement and NETs in COVID-19 immunothrombosis. This study supports strategies against severe acute respiratory syndrome coronavirus 2 that exploit complement or NETosis inhibition.

Immune Alterations in a Patient with SARS-CoV-2-Related Acute Respiratory Distress Syndrome

We report a longitudinal analysis of the immune response associated with a fatal case of COVID-19 in Europe. This patient exhibited a rapid evolution towards multiorgan failure. SARS-CoV-2 was detected in multiple nasopharyngeal, blood, and pleural samples, despite antiviral and immunomodulator treatment. Clinical evolution in the blood was marked by an increase (2-3-fold) in differentiated effector T cells expressing exhaustion (PD-1) and senescence (CD57) markers, an expansion of antibody-secreting cells, a 15-fold increase in γδ T cell and proliferating NK-cell populations, and the total disappearance of monocytes, suggesting lung trafficking. In the serum, waves of a pro-inflammatory cytokine storm, Th1 and Th2 activation, and markers of T cell exhaustion, apoptosis, cell cytotoxicity, and endothelial activation were observed until the fatal outcome. This case underscores the need for well-designed studies to investigate complementary approaches to control viral replication, the source of the hyperinflammatory status, and immunomodulation to target the pathophysiological response. The investigation was conducted as part of an overall French clinical cohort assessing patients with COVID-19 and registered in clinicaltrials.gov under the following number: NCT04262921.

Lung ultrasound predicts histological lung injury in a neonatal model of acute respiratory distress syndrome

RATIONALE

Point-of-care ultrasound (POCUS) is used to evaluate pulmonary edema in adults with acute respiratory distress syndrome (ARDS). Its use has not been validated in neonatal models.

OBJECTIVES

We compared an in vivo lung ultrasound score against clinical and histological markers of acute lung injury, in a neonatal animal model, hypothesizing that POCUS would sensitively diagnose early acute lung injury in neonates and discern its severity.

METHODS

Fifteen anesthetized, ventilated 3-day-old neonatal piglets were divided into controls, moderate lung injury, or severe lung injury by graded treatment with oleic acid. Degree of lung injury was quantified at baseline, immediately after oleic acid administration, and 1 hour after the evolution of acute lung injury, by blood gases, ventilation parameters and calculated oxygenation deficit; hemodynamic indices by echocardiography, and lung ultrasound obtained in an 8-region grid of anterior and posterior zones, semi-quantitatively analyzed by a blinded observer. Lungs were inflation-fixed postmortem at last mean airway pressure, for histological assessment.

RESULTS

Acute lung injury manifested in oleic acid-treated groups as dose-dependent capillary leak causing intravascular depletion and cardiac failure, hypoxemia with increasing intrapulmonary shunt fraction, decreased lung compliance, and resistance. Ultrasound scores of anterior regions distinguished moderate from severe injury; scores in posterior regions reached maximum values immediately after lung injury. POCUS score correlated with calculated intrapulmonary shunt fraction (R²  = .65) and with histological injury score (R²  = .61), P < .01.

CONCLUSION

We conclude that POCUS may be valuable in neonates for early quantification of acute lung injury or ARDS; and that nondependent ultrasound regions clearly distinguish severity of pulmonary edema.

Proning Patients With COVID-19: A Review of Equipment and Methods

OBJECTIVE

To identify and critically evaluate methods for proning patients with COVID-19 in the intensive care unit (ICU).

BACKGROUND

Acute respiratory distress syndrome (ARDS) is common in hospitalized patients with COVID-19. Proning improves blood oxygenation and survival rates in these patients but is not commonly performed due to the difficulty of the procedure.

METHODS

An academic literature review, internet video search, and consultation with five subject-matter experts was performed to identify known methods for proning. Evaluation of each method considered the number of healthcare workers required, physical stresses on staff, risk of adverse events to patients, and equipment cost and availability.

RESULTS

Several variations of manual techniques and-lift assisted techniques were identified in addition to a specialized proning bed. Manual methods require more healthcare workers, higher physical stresses, and greater risk of adverse events than lift-assisted methods or the proning bed.

CONCLUSION

Both the specialized proning bed and a lift-assisted method using straps largely eliminated manual forces required for proning while allowing for a controlled lowering and positioning of the patient.

APPLICATION

This review will guide practitioners to the most suitable methods for proning patients in the ICU.

Cardiac Involvment in COVID-19-Related Acute Respiratory Distress Syndrome

The cardiac involvement in Coronavirus disease (COVID-19) is still under evaluation, especially in severe COVID-19-related Acute Respiratory Distress Syndrome (ARDS). The cardiac involvement was assessed by serial troponin levels and echocardiograms in 28 consecutive patients with COVID-19 ARDS consecutively admitted to our Intensive Care Unit from March 1 to March 31. Twenty-eight COVID-19 patients (aged 61.7 ± 10 years, males 79%). The majority was mechanically ventilated (86%) and 4 patients (14%) required veno-venous extracorporeal membrane oxygenation. As of March 31, the Intensive Care Unit mortality rate was 7%, whereas 7 patients were discharged (25%) with a length of stay of 8.2 ±5 days. At echocardiographic assessment on admission, acute core pulmonale was detected in 2 patients who required extracorporeal membrane oxygenation support. Increased systolic arterial pressure was detected in all patients. Increased Troponin T levels were detectable in 11 patients (39%) on admission. At linear regression analysis, troponin T showed a direct relationship with C-reactive Protein (R square: 0.082, F: 5.95, p = 0.017). In conclusions, in COVID-19-related ARDS, increased in Tn levels was common but not associated with alterations in wall motion kinesis, thus suggesting that troponin T elevation is likely to be multifactorial, mainly linked to disease severely (as inferred by the relation between Tn and C-reactive Protein). The increase in systolic pulmonary arterial pressures observed in all patients may be related to hypoxic vasoconstriction. Further studies are needed to confirm our findings in larger cohorts.

May the neutrophil-to-lymphocyte ratio at admission predict the occurrence and the severity of ARDS after blunt chest trauma patients? A retrospective study

INTRODUCTION

In blunt chest trauma patients, the activation of inflammatory response is thought to be one of the pathophysiological pathways leading to delayed acute respiratory distress syndrome(ARDS). The main objective of the study was to assess the performance of the neutrophil-lymphocyte ratio(NLR) for prediction of delayed ARDS. The secondary objective was to compare NLR in patients with traumarelated focal and non-focal ARDS.

METHODS

Over a 2-year period, every adult patient triaged to our level 1 trauma center with multiple rib fractures and PaO 2 /FiO 2 ratio > 200 at admission were retrospectively included. The NLR was recorded at admission in the Emergency Department(ED). The main study outcome was the occurrence of moderate to severe ARDS within 5 days after admission according to Berlin criteria. Two phenotypes (focal and non-focal ARDS) were determined based on the closest chest CT regarding the ARDS onset.

RESULTS

216 patients were included and 42(19%) underwent moderate to severe ARDS within 5 days after ED admission (focal, N = 26 [12%] and non-focal, N = 16 [7%]). The NLR at ED admission was not statistically different between patients who developed or not a delayed ARDS (14 ± 13 vs. 11 ± 8,p = 0.095), although patients with non-focal ARDS presented higher NLR ratio than focal ARDS (21 ± 18 p < 0.0001). The AUC for NLR at ED in predicting delayed ARDS was 0.53.

CONCLUSION

In blunt chest trauma patients, the NLR at ED admission was unable to predict delayed ARDS over the five first days post-injury. Although not clinically relevant, the NLR was higher in patients with non focal ARDS.

A comparison of four different models of acute respiratory distress syndrome in sheep

BACKGROUND

Acute respiratory distress syndrome (ARDS) can have various causes. The study objective was to investigate whether different pathophysiologic models of ARDS would show different respiratory, cardiovascular and inflammatory outcomes.

METHODS

We performed a prospective, randomized study in 27 ventilated ewes inducing ARDS using three different techniques to mimic the pulmonary causes of ARDS (ARDSp): warm saline lavage (n = 6), intratracheal hydrochloric acid (HCl; n = 6), intratracheal albumin (n = 10), and one technique to mimic an extrapulmonary cause of ARDS (ARDSexp): intravenous lipopolysaccharide (LPS iv; n = 5). ARDS was defined when PaO2 was < 15 kPa (112 mmHg) when ventilated with PEEP 10 cm H2O and FiO2 = 1.0. The effects on gas exchange were investigated by calculating the oxygenation index (OI) and the ventilation efficacy index (VEI) every 30 min for a period of 4 h. Post mortem lung lavage was performed to obtain broncho-alveolar lavage fluid (BALF) to assess lung injury and inflammation. Lung injury and inflammation were assessed by measuring the total number and differentiation of leukocytes, the concentration of protein and disaturated phospholipids, and interleukine-6 and -8 in the BALF. Histology of the lung was evaluated by measuring the mean alveolar size, alveolar wall thickness and the lung injury score system by Matute-Bello et al., as markers of lung injury. The concentration of interleukin-6 was determined in plasma, as a marker of systematic inflammation.

RESULTS

The OI and VEI were most affected in the LPS iv group and thereafter the HCl group, after meeting the ARDS criteria. Diastolic blood pressure was lowest in the LPS iv group. There were no significant differences found in the total number and differentiation of leukocytes, the concentration of protein and disaturated phospholipids, or interleukin-8 in the BALF, histology of the lung and the lung injury score. IL-6 in BALF and plasma was highest in the LPS iv group, but no significant differences were found between the other groups. It took a significantly longer period of time to meet the ARDS criteria in the LPS iv group.

CONCLUSIONS

The LPS model caused the most severe pulmonary and cardiovascular insufficiency. Surprisingly, there were limited significant differences in lung injury and inflammatory markers, despite the different pathophysiological models, when the clinical definition of ARDS was applied.

Clinical Characteristics and Predictors of Disease Progression in Severe Patients with COVID-19 Infection in Jiangsu Province, China: A Descriptive Study

BACKGROUND

We studied patients with coronavirus disease 2019 (COVID-19) infected by severe acute respiratory syndrome coronavirus 2, a virus that originated in Wuhan, China, and is spreading over the country including Jiangsu Province. We studied the clinical characteristics and therapies of severe cases in Jiangsu Province.

METHODS

A multicenter retrospective cohort study was conducted to analyze clinical, laboratory data and treatment of 60 severe cases with COVID-19 infection in Jiangsu Province between January 24, 2020 and April 20, 2020. The improvement and deterioration subgroups were compared to identify predictors of disease progression.

RESULTS

A total of 653 infected cases with COVID-19 were reported in Jiangsu Province, of which 60 severe cases were included in this study. Up until April 20, 2020, the mortality of severe patients was 0%. The median age was 57 years. The average body mass index of these patients was 25 kg/m². White blood cell counts decreased in 45.0% of patients, lymphopenia in 63.3%, thrombocytopenia in 13.3% and procalcitonin levels in 88.3% of the patients were less than 0.5 ng/mL. There were no statistically significant differences in immunoglobulin therapy and GCs therapy between the improvement and deterioration subgroups. Logistic regression analysis identified higher levels of troponin T (odds ratio [OR]: 1.04; 95% confidence interval [CI]: 1.00-1.08; P = 0.04), antiviral therapy with aerosol inhalation of interferon (OR: 6.33; 95% CI: 1.18-33.98; P = 0.03), and the application of non-invasive mechanical ventilation (OR: 1.99; 95%CI: 1.17-3.41; P = 0.01) as predictors of disease progression, whereas higher lymphocyte count (OR: 0.11; 95% CI: 0.02-0.57; P = 0.01) and early prone ventilation were associated with improvement (OR: 0.11; 95% CI: 0.01-0.98; P = 0.04).

CONCLUSIONS

COVID-19 infection had a low mortality rate in Jiangsu Province, China. The higher levels of troponin T and lower lymphocyte count were predictors of disease progression. Early prone ventilation may be an effective treatment for severe cases.

Elevated Plasmin(ogen) as a Common Risk Factor for COVID-19 Susceptibility

Patients with hypertension, diabetes, coronary heart disease, cerebrovascular illness, chronic obstructive pulmonary disease, and kidney dysfunction have worse clinical outcomes when infected with SARS-CoV-2, for unknown reasons. The purpose of this review is to summarize the evidence for the existence of elevated plasmin(ogen) in COVID-19 patients with these comorbid conditions. Plasmin, and other proteases, may cleave a newly inserted furin site in the S protein of SARS-CoV-2, extracellularly, which increases its infectivity and virulence. Hyperfibrinolysis associated with plasmin leads to elevated D-dimer in severe patients. The plasmin(ogen) system may prove a promising therapeutic target for combating COVID-19.

Phenotype and kinetics of SARS-CoV-2-specific T cells in COVID-19 patients with acute respiratory distress syndrome

SARS-CoV-2 has been identified as the causative agent of a global outbreak of respiratory tract disease (COVID-19). In some patients the infection results in moderate to severe acute respiratory distress syndrome (ARDS), requiring invasive mechanical ventilation. High serum levels of IL-6, IL-10 and an immune hyperresponsiveness referred to as a 'cytokine storm' have been associated with poor clinical outcome. Despite the large numbers of COVID-19 cases and deaths, information on the phenotype and kinetics of SARS-CoV-2-specific T cells is limited. Here, we studied 10 COVID-19 patients who required admission to an intensive care unit and detected SARS-CoV-2-specific CD4+ and CD8+ T cells in 10 out of 10 and 8 out of 10 patients, respectively. We also detected low levels of SARS-CoV-2-reactive T cells in 2 out of 10 healthy controls not previously exposed to SARS-CoV-2, which is indicative of cross-reactivity due to past infection with 'common cold' coronaviruses. The strongest T-cell responses were directed to the spike (S) surface glycoprotein, and SARS-CoV-2-specific T cells predominantly produced effector and Th1 cytokines, although Th2 and Th17 cytokines were also detected. Furthermore, we studied T-cell kinetics and showed that SARS-CoV-2-specific T cells are present relatively early and increase over time. Collectively, these data shed light on the potential variations in T-cell responses as a function of disease severity, an issue that is key to understanding the potential role of immunopathology in the disease, and also inform vaccine design and evaluation.

Decreased microRNA 103 and microRNA 107 predict increased risks of acute respiratory distress syndrome and 28-day mortality in sepsis patients

We aimed to investigate the predictive value of microRNA 103 (MIR103) and microRNA 107 (MIR107) for acute respiratory distress syndrome (ARDS) risk, as well as their correlations with overall disease severity and prognosis in sepsis patients.Plasma samples were collected from 196 sepsis patients within 24 hours after enrollment and from 196 healthy individuals (as healthy controls (HCs)) at enrollment. Plasma MIR103 and MIR107 were detected by reverse transcription-quantitative polymerase chain reaction.MIR103 and MIR107 were both decreased in ARDS sepsis patients and non-ARDS sepsis patients compared to HCs, and were reduced in ARDS sepsis patients than non-ARDS sepsis patients. Decreased MIR103 (area under curve (AUC): 0.727, 95% confidence interval (CI): 0.619-0.835) and MIR107 (AUC: 0.694, 95% CI: 0.577-0.811) predicted increased ARDS risk in sepsis patients. Meanwhile, MIR103 and MIR107 were negatively correlated with acute pathologic and chronic health evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score, serum creatinine, C-reactive protein, tumor necrosis factor, interleukin 1β, interleukin 6 and interleukin 8, while positively correlated with albumin in sepsis patients. For prognosis, 28-day mortality was increased in ARDS sepsis patients compared to non-ARDS sepsis patients. Finally, MIR103 and MIR107 were reduced in deaths than survivors of sepsis patients, and decreased MIR103 (AUC: 0.704, 95% CI: 0.626-0.782) as well as MIR107 (AUC: 0.649, 95% CI: 0.569-0.729) predicted increased 28-day mortality risk in sepsis patients.MiR-103 and MIR107 were predictive biomarkers for risks of ARDS and 28-day mortality in sepsis patients, which might improve the management of sepsis.

Biomarker Panels in Critical Care

Biomarker panels have the potential to advance the field of critical care medicine by stratifying patients according to prognosis and/or underlying pathophysiology. This article discusses the discovery and validation of biomarker panels, along with their translation to the clinical setting. The current literature on the use of biomarker panels in sepsis, acute respiratory distress syndrome, and acute kidney injury is reviewed.

Risk of acute respiratory failure among hospitalized patients with various admission serum albumin levels: A cohort study

Serum albumin is a marker of nutritional and frailty status. This study aimed to assess the association between serum albumin at the time of admission and the risk of acute respiratory failure (ARF) in hospitalized patientsThis cohort study, performed at a tertiary referral hospital, included all hospitalized adult patients from January 2009 to December 2013 who had serum albumin measurement and were not on mechanical ventilation within 24 hours of hospital admission. Serum albumin was stratified into 2.4, 2.5 to 2.9, 3.0 to 3.4, 3.5 to 3.9, 4.0 to 4.4, and ≥4.5 g/dL. Multivariate logistic regression analysis was performed to obtain adjusted odds ratio (OR) of risk of ARF requiring mechanical ventilation based on various admission serum albumin levels.Of 12,719 patients, ARF requiring mechanical ventilation occurred in 1128 (8.9%) during hospitalization. Hypoalbuminemia was associated with increased risk of ARF, in particular when serum albumin was ≤2.4 g/dL. Compared with serum albumin of 4.0-4.4 g/dL, serum albumin ≤2.4 g/dL at admission was associated with 2.38-time higher odds of ARF during hospitalization (OR 2.38, 95% confidence interval [CI] 1.84-3.07). In contrast, elevated serum albumin ≥4.5 g/dL was associated with lower odds of ARF (OR 0.68, 95% CI 0.48-0.97).Admission serum albumin level lower than 3.5 g/dL was associated with a higher risk of ARF requiring mechanical ventilation, whereas elevated serum albumin level at least 4.5 g/dL was associated with a lower risk of ARF. Therefore, admission albumin level at admission might be useful in the prediction of ARF during hospitalization.

Development and validation of parsimonious algorithms to classify acute respiratory distress syndrome phenotypes: a secondary analysis of randomised controlled trials

BACKGROUND

Using latent class analysis (LCA) in five randomised controlled trial (RCT) cohorts, two distinct phenotypes of acute respiratory distress syndrome (ARDS) have been identified: hypoinflammatory and hyperinflammatory. The phenotypes are associated with differential outcomes and treatment response. The objective of this study was to develop parsimonious models for phenotype identification that could be accurate and feasible to use in the clinical setting.

METHODS

In this retrospective study, three RCT cohorts from the National Lung, Heart, and Blood Institute ARDS Network (ARMA, ALVEOLI, and FACTT) were used as the derivation dataset (n=2022), from which the machine learning and logistic regression classifer models were derived, and a fourth (SAILS; n=715) from the same network was used as the validation test set. LCA-derived phenotypes in all of these cohorts served as the reference standard. Machine-learning algorithms (random forest, bootstrapped aggregating, and least absolute shrinkage and selection operator) were used to select a maximum of six important classifier variables, which were then used to develop nested logistic regression models. Only cases with complete biomarker data in the derivation dataset were used for variable selection. The best logistic regression models based on parsimony and predictive accuracy were then evaluated in the validation test set. Finally, the models' prognostic validity was tested in two external ARDS clinical trial datasets (START and HARP-2) by assessing mortality at days 28, 60, and 90 and ventilator-free days to day 28.

FINDINGS

The six most important classifier variables were interleukin (IL)-8, IL-6, protein C, soluble tumour necrosis factor receptor 1, bicarbonate, and vasopressor use. From the nested models, three-variable (IL-8, bicarbonate, and protein C) and four-variable (3-variable plus vasopressor use) models were adjudicated to be the best performing. In the validation test set, both models showed good accuracy (AUC 0·94 [95% CI 0·92-0·95] for the three-variable model and 0·95 [95% CI 0·93-0·96] for the four-variable model) against LCA classifications. As with LCA-derived phenotypes, the hyperinflammatory phenotype as identified by the classifier model was associated with higher mortality at day 90 (87 [39%] of 223 patients vs 112 [23%] of 492 patients; p<0·0001) and fewer ventilator-free days (median 14 days [IQR 0-22] vs 22 days [0-25]; p<0·0001). In the external validation datasets, three-variable models developed in the derivation dataset identified two phenotypes with distinct clinical features and outcomes consistent with previous findings, including differential survival with simvastatin versus placebo in HARP-2 (p=0·023 for survival at 28 days).

INTERPRETATION

ARDS phenotypes can be accurately identified with parsimonious classifier models using three or four variables. Pending the development of real-time testing for key biomarkers and prospective validation, these models could facilitate identification of ARDS phenotypes to enable their application in clinical trials and practice.

FUNDING

National Institutes of Health.

Plasma Mitochondrial DNA Levels Are Associated With ARDS in Trauma and Sepsis Patients

BACKGROUND

Critically ill patients who develop ARDS have substantial associated morbidity and mortality. Circulating mitochondrial DNA (mtDNA) released during critical illness causes endothelial dysfunction and lung injury in experimental models. This study hypothesized that elevated plasma mtDNA is associated with ARDS in critically ill patients with trauma and sepsis.

METHODS

Plasma mtDNA concentrations were measured at ED presentation and approximately 48 h later in separate prospective cohorts of critically ill patients with trauma and sepsis. ARDS was classified according to the Berlin definition. The association of mtDNA with ARDS was tested by using multivariable logistic regression, adjusted for covariates previously shown to contribute to ARDS risk in each population.

RESULTS

ARDS developed in 41 of 224 (18%) trauma patients and in 45 of 120 (38%) patients with sepsis. Forty-eight-hour mtDNA levels were significantly associated with ARDS (trauma: OR, 1.58/log copies/μL; 95% CI, 1.14-2.19 [P = .006]; sepsis: OR, 1.52/log copies/μL; 95% CI, 1.12-2.06 [P = .007]). Plasma mtDNA on presentation was not significantly associated with ARDS in either cohort. In patients with sepsis, 48-h mtDNA was more strongly associated with ARDS among those with a nonpulmonary infectious source (OR, 2.20/log copies/μL; 95% CI, 1.36-3.55 [P = .001], n = 69) than those with a pulmonary source (OR, 1.04/log copies/μL; 95% CI, 0.68-1.59 [P = .84], n = 51; P = .014 for interaction).

CONCLUSIONS

Plasma mtDNA levels were associated with incident ARDS in two critical illness populations. Given supportive preclinical data, our findings suggest a potential link between circulating mtDNA and lung injury and merit further investigation as a potentially targetable mediator of ARDS.

Plasma sRAGE Acts as a Genetically Regulated Causal Intermediate in Sepsis-associated Acute Respiratory Distress Syndrome

Rationale: Acute respiratory distress syndrome (ARDS) lacks known causal biomarkers. Plasma concentrations of sRAGE (soluble receptor for advanced glycation end products) strongly associate with ARDS risk. However, whether plasma sRAGE contributes causally to ARDS remains unknown.Objectives: Evaluate plasma sRAGE as a causal intermediate in ARDS by Mendelian randomization (MR), a statistical method to infer causality using observational data.Methods: We measured early plasma sRAGE in two critically ill populations with sepsis. The cohorts were whole-genome genotyped and phenotyped for ARDS. To select validated genetic instruments for MR, we regressed plasma sRAGE on genome-wide genotypes in both cohorts. The causal effect of plasma sRAGE on ARDS was inferred using the top variants with significant associations in both populations (P < 0.01, R2 > 0.02). We applied the inverse variance-weighted method to obtain consistent estimates of the causal effect of plasma sRAGE on ARDS risk.Measurements and Main Results: There were 393 European and 266 African ancestry patients in the first cohort and 843 European ancestry patients in the second cohort. Plasma sRAGE was strongly associated with ARDS risk in both populations (odds ratio, 1.86; 95% confidence interval [1.54-2.25]; 2.56 [2.14-3.06] per log increase). Using genetic instruments common to both populations, plasma sRAGE had a consistent causal effect on ARDS risk with a β estimate of 0.50 (95% confidence interval [0.09-0.91] per log increase).Conclusions: Plasma sRAGE is genetically regulated during sepsis, and MR analysis indicates that increased plasma sRAGE leads to increased ARDS risk, suggesting plasma sRAGE acts as a causal intermediate in sepsis-related ARDS.

Host-Response Subphenotypes Offer Prognostic Enrichment in Patients With or at Risk for Acute Respiratory Distress Syndrome

OBJECTIVES

Classification of patients with acute respiratory distress syndrome into hyper- and hypoinflammatory subphenotypes using plasma biomarkers may facilitate more effective targeted therapy. We examined whether established subphenotypes are present not only in patients with acute respiratory distress syndrome but also in patients at risk for acute respiratory distress syndrome (ARFA) and then assessed the prognostic information of baseline subphenotyping on the evolution of host-response biomarkers and clinical outcomes.

DESIGN

Prospective, observational cohort study.

SETTING

Medical ICU at a tertiary academic medical center.

PATIENTS

Mechanically ventilated patients with acute respiratory distress syndrome or ARFA.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We performed longitudinal measurements of 10 plasma biomarkers of host injury and inflammation. We applied unsupervised latent class analysis methods utilizing baseline clinical and biomarker variables and demonstrated that two-class models (hyper- vs hypoinflammatory subphenotypes) offered improved fit compared with one-class models in both patients with acute respiratory distress syndrome and ARFA. Baseline assignment to the hyperinflammatory subphenotype (39/104 [38%] acute respiratory distress syndrome and 30/108 [28%] ARFA patients) was associated with higher severity of illness by Sequential Organ Failure Assessment scores and incidence of acute kidney injury in patients with acute respiratory distress syndrome, as well as higher 30-day mortality and longer duration of mechanical ventilation in ARFA patients (p < 0.0001). Hyperinflammatory patients exhibited persistent elevation of biomarkers of innate immunity for up to 2 weeks postintubation.

CONCLUSIONS

Our results suggest that two distinct subphenotypes are present not only in patients with established acute respiratory distress syndrome but also in patients at risk for its development. Hyperinflammatory classification at baseline is associated with higher severity of illness, worse clinical outcomes, and trajectories of persistently elevated biomarkers of host injury and inflammation during acute critical illness compared with hypoinflammatory patients. Our findings provide strong rationale for examining treatment effect modifications by subphenotypes in randomized clinical trials to inform precision therapeutic approaches in critical care.

The Association Between Serum Uric Acid Level and Prognosis in Critically Ill Patients, Uric Acid as a Prognosis Predictor

BACKGROUND

Uric acid is synthesized from xanthine via xanthine oxidase as an end-product of purine metabolism. Uric acid is a major non-enzymatic antioxidant in the blood, and it exerts a protective action on vitamin C. There are a limited number of ICU studies related to uric acid, which is a valuable prognostic biomarker. This study aimed to evaluate the utility of uric acid as a biomarker in predicting the outcomes of critically ill patients.

METHODS

This prospective, multi-centered cohort study included 128 patients from two different intensive care units who met the study inclusion criteria between May 2017 and October 2017. Study inclusion criteria were first admission to the ICU, age > 18 years, and ICU stay > 24 hours. In each patient, baseline serum uric acid levels were measured after acute interventions, prior to the initiation of the treatment process.

RESULTS

When comparing the last uric acid levels of patients, the median last uric acid levels in the non-survival and survival groups were significantly different (p = 0.001). A last uric acid level > 4.5 mg/dL was associated with a 2.638 times higher risk (relative risk) for mortality. According to ROC analysis, a cutoff value of 1.5 for the ratio between the last two uric acid levels had a sensitivity of 0.21 and a specificity of 0.96 for predicting mortality. A 1.5-fold increase in the uric acid level yielded a positive predictive value of 92.6% and a negative predictive value of 65.2% for predicting mortality. The median uric level in the patient subset with ARDS, was significantly higher than those without ARDS (p = 0.001).

CONCLUSIONS

Results of this study indicate that a time-dependent increase in uric acid levels can be used as an important biomarker for predicting mortality in critically ill patients; further, uric acid levels should possibly be included in the current mortality risk scoring systems. In addition, elevation of uric acid, a simple, inexpensive, and readily available biomarker, may provide guidance in the diagnostic stage and in predicting clinical outcomes of patients with sepsis or ARDS.

MiR-150 attenuates LPS-induced acute lung injury via targeting AKT3

Acute lung injury (ALI) and its severe manifestation of acute respiratory distress syndrome (ARDS) in human lung are induced by inflammatory cytokines and endogenous factors such as miRNAs. However, the role of miR-150 in lipopolysaccharide (LPS)-induced ALI is not clear. Here, we found miR-150 expression was significantly reduced in the serum of patients with ARDS, and negatively associated with the disease severity and 28-day survival of ARDS. In vivo, miR-150 decreased total cell and neutrophil counts, and production of inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) as well as levels of total protein, albumin and IgM in the bronchoalveolar lavage (BAL) fluid in LPS-induced ALI mice. Meanwhile, miR-150 improved the 72 h survival rate of LPS-induced ALI mice. In-vitro assays demonstrated that miR-150 alleviated LPS-induced A549 cell apoptosis, autophagy, and release of inflammatory cytokines. Further, AKT3 was a direct target of miR-150. Silencing of AKT3 partially reversed LPS-induced A549 cell injury, and enhanced the protective effects of miR-150. In addition, miR-150 or si-AKT3 effectively inhibited the phosphorylation levels of c-Jun N-terminal kinase (JNK) and nuclear factor-κB (NF-κB) (p65 and IκBα). In conclusion, miR-150 alleviated LPS-induced acute lung injury via directly targeting AKT3 expression or regulating JNK and NF-κB pathways, which may be a promising therapeutic strategy to treat ALI/ARDS.

Serum Exosomal MicroRNAs Predict Acute Respiratory Distress Syndrome Events in Patients with Severe Community-Acquired Pneumonia

BACKGROUND

Severe community-acquired pneumonia (SCAP) requiring intensive care unit (ICU) treatment commonly causes acute respiratory distress syndrome (ARDS) with high mortality. This study was aimed at evaluating whether microRNAs (miRNAs) in circulating exosomes have the predictive values for patients at risk of developing ARDS due to SCAP.

METHODS

ARDS/ALI-relevant miRNAs were obtained by literature search. Exosomes in serum were isolated by ultracentrifugation method and identified by Transmission Electron Microscopy. Then the miR profiling in the exosomes using real-time PCR was analyzed in SCAP patients with or without ARDS. Moreover, multivariate Cox proportional regression analysis was performed to estimate the odds ratio of miRNA for the occurrence of ARDS and prognosis. The receiver operating characteristics (ROC) curves were calculated to discriminate ARDS cases. Finally, the Kaplan-Meier curve using log-rank method was performed to test the equality for survival distributions with different miRNA classifiers.

RESULTS

A total of 53 SCAP patients were finally recruited. Ten miRNAs were picked out. Further, a subset of exosomal miRNAs, including the miR-146a, miR-27a, miR-126, and miR-155 in ARDS group exhibited significantly elevated levels than those in non-ARDS group. The combined expression of miR-126, miR-27a, miR-146a, and miR-155 predicted ARDS with an area under the curve of 0.909 (95 % CI 0.815 -1). Only miR-126 was selected to have potential to predict the 28-day mortality (OR=1.002, P=0.024) with its median value classifier.

CONCLUSIONS

The altered levels of circulating exosomal microRNAs may be useful biologic confirmation of ARDS in patients with SCAP.