National incidence rates for Acute Respiratory Distress Syndrome (ARDS) and ARDS cause-specific factors in the United States (2006-2014)

BMAL1 plays a crucial role in immune homeostasis during sepsis-induced acute lung injury

Sepsis is a widespread and life-threatening disease characterised by infection-triggered immune hyperactivation and cytokine storms, culminating in tissue damage and multiple organ dysfunction syndrome. BMAL1 is a pivotal transcription factor in the circadian clock that plays a crucial role in maintaining immune homeostasis. BMAL1 dysregulation has been implicated in inflammatory diseases and immunodeficiency. However, the mechanisms underlying BMAL1 disruption in sepsis-induced acute lung injury (ALI) remain poorly understood. In vitro, we used THP1 and mouse peritoneal macrophages to elucidate the potential mechanism of BMAL1 function in sepsis. In vivo, an endotoxemia model was used to investigate the effect of BMAL1 on sepsis and the therapeutic role of targeting CXCR2. We showed that BMAL1 significantly affected the regulation of innate immunity in sepsis-induced ALI. BMAL1 deficiency in the macrophages exacerbated systemic inflammation and sepsis-induced ALI. Mechanistically, BMAL1 acted as a transcriptional suppressor and regulated the expression of CXCL2. BMAL1 deficiency in macrophages upregulated CXCL2 expression, increasing the recruitment of polymorphonuclear neutrophils and the formation of neutrophil extracellular traps (NETs) by binding to the chemokine receptor CXCR2, thereby intensifying lung injury in a sepsis model. Furthermore, a selective inhibitor of CXCR2, SB225002, exerted promising therapeutic effects by markedly reducing neutrophil infiltration and NETs formation and alleviating lung injury. Importantly, CXCR2 blockade mitigated multiple organ dysfunction. Collectively, these findings suggest that BMAL1 controls the CXCL2/CXCR2 pathway, and the therapeutic efficacy of targeting CXCR2 in sepsis has been validated, presenting BMAL1 as a potential therapeutic target for lethal infections.

ARDSFlag: an NLP/machine learning algorithm to visualize and detect high-probability ARDS admissions independent of provider recognition and billing codes

BACKGROUND

Despite the significance and prevalence of acute respiratory distress syndrome (ARDS), its detection remains highly variable and inconsistent. In this work, we aim to develop an algorithm (ARDSFlag) to automate the diagnosis of ARDS based on the Berlin definition. We also aim to develop a visualization tool that helps clinicians efficiently assess ARDS criteria.

METHODS

ARDSFlag applies machine learning (ML) and natural language processing (NLP) techniques to evaluate Berlin criteria by incorporating structured and unstructured data in an electronic health record (EHR) system. The study cohort includes 19,534 ICU admissions in the Medical Information Mart for Intensive Care III (MIMIC-III) database. The output is the ARDS diagnosis, onset time, and severity.

RESULTS

ARDSFlag includes separate text classifiers trained using large training sets to find evidence of bilateral infiltrates in radiology reports (accuracy of 91.9%±0.5%) and heart failure/fluid overload in radiology reports (accuracy 86.1%±0.5%) and echocardiogram notes (accuracy 98.4%±0.3%). A test set of 300 cases, which was blindly and independently labeled for ARDS by two groups of clinicians, shows that ARDSFlag generates an overall accuracy of 89.0% (specificity = 91.7%, recall = 80.3%, and precision = 75.0%) in detecting ARDS cases.

CONCLUSION

To our best knowledge, this is the first study to focus on developing a method to automate the detection of ARDS. Some studies have developed and used other methods to answer other research questions. Expectedly, ARDSFlag generates a significantly higher performance in all accuracy measures compared to those methods.

Pneumothorax in acute respiratory distress syndrome on extracorporeal membrane oxygenation support

INTRODUCTION

Pneumothorax is associated with poor prognosis in patients with acute respiratory distress syndrome (ARDS). We sought to examine the outcomes of patients who are supported on veno-venous extracorporeal membrane oxygenation (VV ECMO) and develop a pneumothorax.

METHODS

We retrospectively reviewed all adult VV ECMO patients supported for ARDS between 8/2014-7/2020 at our institution, excluding patients with recent lung resection and trauma. Clinical outcomes were compared between patients with a pneumothorax to those without a pneumothorax.

RESULTS

Two hundred eighty patients with ARDS on VV ECMO were analyzed. Of those, 213 did not have a pneumothorax and 67 did. Patients with a pneumothorax had a longer duration of ECMO support (30 days [16-55] versus 12 [7-22], p < 0.001) and hospital length of stay (51 days [27-93] versus 29 [18-49], p < 0.001), and lower survival-to-discharge (58.2% versus 77.5%, p = 0.002) compared to patients without a pneumothorax. Controlling for age, BMI, sex, RESP score and pre-ECMO ventilator days, the odds ratio of survival-to-discharge was 0.41 (95% CI 0.22-0.78) in patients with a pneumothorax compared to those without. There was a lower incidence of significant bleeding when chest tubes were placed by proceduralist services (2.4% versus 16.2%, p = 0.03). Removal of the chest tube prior to ECMO decannulation compared to removal after decannulation was associated with need for replacement (14.3% versus 0%, p = 0.01).

CONCLUSION

Patients who develop a pneumothorax and are supported with VV ECMO for ARDS have longer duration on ECMO and decreased survival. Further studies are needed to assess risk factors for development of pneumothorax in this patient population.

Hospital Outcomes in Patients Who Developed Acute Respiratory Distress Syndrome After Community-Acquired Pneumonia

Purpose: To identify risk factors for and outcomes in acute respiratory distress syndrome (ARDS) in patients hospitalized with community-acquired pneumonia (CAP). Methods: This is a retrospective study using the Premier Healthcare Database between 2016 and 2020. Patients diagnosed with pneumonia, requiring mechanical ventilation (MV), antimicrobial therapy, and hospital admission ≥2 days were included. Multivariable regression models were used for outcomes including in-hospital mortality, hospital length of stay (LOS), intensive care unit (ICU) LOS, and days on MV. Results: 1924 (2.7%) of 72 107 patients with CAP developed ARDS. ARDS was associated with higher mortality (33.7% vs 18.9%; adjusted odds ratio 2.4; 95% confidence interval [CI] 2.16-2.66), longer hospital LOS (13 vs 9 days; adjusted incidence risk ratio (aIRR) 1.24; 95% CI 1.20-1.27), ICU LOS (9 vs 5 days; aIRR 1.51; 95% CI 1.46-1.56), more MV days (8 vs 5; aIRR 1.54; 95% CI 1.48-1.59), and increased hospitalization cost ($46 459 vs $29 441; aIRR 1.50; 95% CI 1.45-1.55). Conclusion: In CAP, ARDS was associated with worse in-patient outcomes in terms of mortality, LOS, and hospitalization cost. Future studies are needed to explore outcomes in patients with CAP with ARDS and explore risk factors for development of ARDS after CAP.

Exploring the ferroptosis-related gene lipocalin 2 as a potential biomarker for sepsis-induced acute respiratory distress syndrome based on machine learning

BACKGROUND

Sepsis is a major cause of mortality in patients, and ARDS is one of the most common outcomes. The pathophysiology of acute respiratory distress syndrome (ARDS) caused by sepsis is significantly impacted by genes related to ferroptosis.

METHODS

In this study, Weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) networks, functional enrichment analysis, and machine learning were employed to identify characterized genes and to construct receiver operating characteristic (ROC) curves. Additionally, DNA methylation levels were quantified and single-cell analysis was conducted. To validate the alterations in the expression of Lipocalin-2 (LCN2) and ferroptosis-related proteins in the in vitro model, Western blotting was carried out, and the changes in intracellular ROS and Fe2+ levels were detected.

RESULTS

A combination of eight machine learning algorithms, including RFE, LASSO, RandomForest, SVM-RFE, GBDT, Bagging, XGBoost, and Boruta, were used with a machine learning model to highlight the significance of LCN2 as a key gene in sepsis-induced ARDS. Analysis of immune cell infiltration showed a positive correlation between neutrophils and LCN2. In a cell model induced by LPS, it was found that Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, was able to reverse the expression of LCN2. Knocking down LCN2 in BEAS-2B cells reversed the LPS-induced lipid peroxidation, Fe2+ levels, ACSL4, and GPX4 levels, indicating that LCN2, a ferroptosis-related gene (FRG), plays a crucial role in mediating ferroptosis.

CONCLUSION

Upon establishing an FRG model for individuals with sepsis-induced ARDS, we determined that LCN2 could be a dependable marker for predicting survival in these patients. This finding provides a basis for more accurate ARDS diagnosis and the exploration of innovative treatment options.

Gut microbiota and its metabolic products in acute respiratory distress syndrome

The prevalence rate of acute respiratory distress syndrome (ARDS) is estimated at approximately 10% in critically ill patients worldwide, with the mortality rate ranging from 17% to 39%. Currently, ARDS mortality is usually higher in patients with COVID-19, giving another challenge for ARDS treatment. However, the treatment efficacy for ARDS is far from satisfactory. The relationship between the gut microbiota and ARDS has been substantiated by relevant scientific studies. ARDS not only changes the distribution of gut microbiota, but also influences intestinal mucosal barrier through the alteration of gut microbiota. The modulation of gut microbiota can impact the onset and progression of ARDS by triggering dysfunctions in inflammatory response and immune cells, oxidative stress, cell apoptosis, autophagy, pyroptosis, and ferroptosis mechanisms. Meanwhile, ARDS may also influence the distribution of metabolic products of gut microbiota. In this review, we focus on the impact of ARDS on gut microbiota and how the alteration of gut microbiota further influences the immune function, cellular functions and related signaling pathways during ARDS. The roles of gut microbiota-derived metabolites in the development and occurrence of ARDS are also discussed.

Interorgan communication networks in the kidney-lung axis

The homeostasis and health of an organism depend on the coordinated interaction of specialized organs, which is regulated by interorgan communication networks of circulating soluble molecules and neuronal connections. Many diseases that seemingly affect one primary organ are really multiorgan diseases, with substantial secondary remote organ complications that underlie a large part of their morbidity and mortality. Acute kidney injury (AKI) frequently occurs in critically ill patients with multiorgan failure and is associated with high mortality, particularly when it occurs together with respiratory failure. Inflammatory lung lesions in patients with kidney failure that could be distinguished from pulmonary oedema due to volume overload were first reported in the 1930s, but have been largely overlooked in clinical settings. A series of studies over the past two decades have elucidated acute and chronic kidney-lung and lung-kidney interorgan communication networks involving various circulating inflammatory cytokines and chemokines, metabolites, uraemic toxins, immune cells and neuro-immune pathways. Further investigations are warranted to understand these clinical entities of high morbidity and mortality, and to develop effective treatments.

Hemoadsorption in acute respiratory distress syndrome patients requiring venovenous extracorporeal membrane oxygenation: a systematic review

BACKGROUND

Venovenous extracorporeal membrane oxygenation (VV ECMO) has been widely used for severe acute respiratory distress syndrome (ARDS) in recent years. However, the role of hemoadsorption in ARDS patients requiring VV ECMO is unclear.

METHODS

Therefore, we conducted a systematic review to describe the effect of hemoadsorption on outcomes of ARDS patients requiring VV ECMO and elucidate the risk factors for adverse outcomes. We conducted and reported a systematic literature review based on the principles derived from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The systematic review searched Embase, CINHAL, and Pubmed databases for studies on ARDS patients receiving hemoadsorption and VV ECMO. The demographic data, clinical data and biological data of the patients were collected.

RESULTS

We ultimately included a total of 8 articles including 189 patients. We characterized the population both clinically and biologically. Our review showed most studies described reductions in inflammatory markers and fluid resuscitation drug dosage in ARDS patients with Coronavirus disease 2019 (COVID-19) or sepsis after hemoadsorption.

CONCLUSION

Because most of the studies have the characteristics of high heterogeneity, we could only draw very cautious conclusions that hemoadsorption therapy may enhance hemodynamic stability in ARDS patients with COVID-19 or sepsis receiving VV ECMO support. However, our results do not allow us to draw conclusions that hemoadsorption could reduce inflammation and mortality. Prospective randomized controlled studies with a larger sample size are needed in the future to verify the role of hemoadsorption in ARDS patients requiring VV ECMO.

Safety of Bioplasma FDP and Hemopure in rhesus macaques after 30% hemorrhage

Objectives

Prehospital transfusion can be life-saving when transport is delayed but conventional plasma, red cells, and whole blood are often unavailable out of hospital. Shelf-stable products are needed as a temporary bridge to in-hospital transfusion. Bioplasma FDP (freeze-dried plasma) and Hemopure (hemoglobin-based oxygen carrier; HBOC) are products with potential for prehospital use. In vivo use of these products together has not been reported. This study assessed the safety of intravenous administration of HBOC+FDP, relative to normal saline (NS), in rhesus macaques (RM).

Methods

After 30% blood volume removal and 30 minutes in shock, animals were resuscitated with either NS or two units (RM size adjusted) each of HBOC+FDP during 60 minutes. Sequential blood samples were collected. After neurological assessment, animals were killed at 24 hours and tissues collected for histopathology.

Results

Due to a shortage of RM during the COVID-19 pandemic, the study was stopped after nine animals (HBOC+FDP, seven; NS, two). All animals displayed physiologic and tissue changes consistent with hemorrhagic shock and recovered normally. There was no pattern of cardiovascular, blood gas, metabolic, coagulation, histologic, or neurological changes suggestive of risk associated with HBOC+FDP.

Conclusion

There was no evidence of harm associated with the combined use of Hemopure and Bioplasma FDP. No differences were noted between groups in safety-related cardiovascular, pulmonary, renal or other organ or metabolic parameters. Hemostasis and thrombosis-related parameters were consistent with expected responses to hemorrhagic shock and did not differ between groups. All animals survived normally with intact neurological function.

Level of evidence

Not applicable.

Ursodeoxycholic acid alleviates sepsis-induced lung injury by blocking PANoptosis via STING pathway

Acute lung injury (ALI), a progressive lung disease mostly caused by sepsis, is characterized by uncontrolled inflammatory responses, increased oxidative stress, pulmonary barrier dysfunction, and pulmonary edema. Ursodeoxycholic acid (UDCA) is a natural bile acid with various pharmacological properties and is extensively utilized in clinical settings for the management of hepatobiliary ailments. Nonetheless, the potential protective effects and mechanism of UDCA on sepsis-induced lung injuries remain unknown. In this study, we reported that UDCA effectively inhibited pulmonary edema, inflammatory cell infiltration, pro-inflammatory cytokines production, and oxidative stress. Furthermore, UDCA treatment significantly alleviated the damage of pulmonary barrier and enhanced alveolar fluid clearance. Importantly, UDCA treatment potently suppressed PANoptosis-like cell death which is demonstrated by the block of apoptosis, pyroptosis, and necroptosis. Mechanistically, UDCA treatment prominently inhibited STING pathway. And the consequential loss of STING substantially impaired the beneficial effects of UDCA treatment on the inflammatory response, pulmonary barrier, and PANoptosis. These results indicate that STING plays a pivotal role in the UDCA treatment against sepsis-induced lung injury. Collectively, our findings show that UDCA treatment can ameliorate sepsis-induced lung injury and verified a previously unrecognized mechanism by which UDCA alleviated sepsis-induced lung injury through blocking PANoptosis-like cell death via STING pathway.

Systematic review of the effect of metabolic syndrome on outcomes due to acute respiratory distress syndrome: a protocol

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is a life-threatening condition commonly seen in the intensive care unit. COVID-19 has dramatically increased the incidence of ARDS-with this rise in cases comes the ability to detect predisposing factors perhaps not recognised before, such as metabolic syndrome (MetS) and its associated conditions (hypertension, obesity, dyslipidaemia and type 2 diabetes mellitus). In this systematic review, we seek to describe the complex relationship between MetS, its associated conditions and ARDS (including COVID-19 ARDS).

METHODS AND ANALYSIS

A systematic search of PubMed, Embase, Cochrane Central Register of Controlled Trials, CINAHL and Web of Science will be conducted. The population of interest is adults with ARDS and MetS (as defined according to the study author recognising that MetS definitions vary) or any MetS-associated condition. The control group will be adult patients with ARDS without MetS or any individual MetS-associated condition. We will search studies published in English, with a date restriction from the year 2000 to June 2023 and employ the search phrases 'metabolic syndrome', 'acute respiratory distress syndrome' and related terms. Search terms including 'dyslipidaemia', 'hypertension', 'diabetes mellitus' and 'obesity' will also be utilised. Outcomes of interest will include mortality (in-hospital, ICU, 28-day, 60-day and 90-day), days requiring mechanical ventilation and hospital and/or ICU length of stay. Study bias will be assessed using the NIH Bias Scale.

ETHICS AND DISSEMINATION

Ethical approval is not required because this study includes previously published and publicly accessible data. Findings from this review will be disseminated via publication in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023405816.

Effects of intravenous sivelestat sodium on prevention of acute respiratory distress syndrome in patients with sepsis: study protocol for a double-blind multicentre randomised controlled trial

INTRODUCTION

Sepsis is one of the most common risk factors for acute respiratory distress syndrome (ARDS). Neutrophil elastase (NE) is believed to be an important mediator of ARDS. When sepsis occurs, a large number of inflammatory factors are activated and released, which makes neutrophils migrate into the lung, eventually leading to the occurrence of ARDS. Sivelestat sodium is an NE inhibitor that can inhibit the inflammatory reaction during systemic inflammatory response syndrome and alleviate lung injury. Therefore, we hypothesise that intravenous sivelestat sodium may prevent the occurrence of ARDS in patients with sepsis.

METHODS AND ANALYSIS

This is a prospective, investigator-initiated, double-blind, adaptive, multicentre, randomised, controlled clinical trial with an adaptive 'sample size re-estimation' design. Patients meeting the inclusion criteria who were transferred into the intensive care unit will be randomly assigned to receive sivelestat sodium or placebo for up to 7 days. The primary outcome is the development of ARDS within 7 days after randomisation. A total of 238 patients will be recruited based on a 15% decrease in the incidence of ARDS in the intervention group in this study. A predefined interim analysis will be performed to ensure that the calculation is reasonable after reaching 50% (120) of the planned sample size.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of ZhongDa Hospital affiliated to Southeast University (identifier: Clinical Ethical Approval No. 2021ZDSYLL153-P03). Results will be submitted for publication in peer-reviewed journals and presented at relevant conferences and meetings.

TRIAL REGISTRATION NUMBER

NCT04973670.

Serum HMGB1 and soluble urokinase plasminogen activator receptor levels aid diagnosis and prognosis prediction of sepsis with acute respiratory distress syndrome

Objective: To study the clinical application of serum HMGB1 and soluble urokinase plasminogen activator receptor (suPAR) expression in sepsis with acute respiratory distress syndrome (ARDS). Methods: Clinical data of 303 septic patients with/without ARDS were documented. Levels of serum inflammatory markers and HMGB1/suPAR were measured. ARDS patients were subdivided into high and low HMGB1/suPAR expression groups and followed up. Results: Serum HMGB1 and suPAR were upregulated in ARDS patients and positively correlated with inflammatory markers. The combination of HMGB1 with suPAR surpassed HMGB1 or suPAR alone in aiding diagnosis of sepsis with ARDS. CRP, PCT, IL-6, HMGB1 and suPAR were independent risk factors for ARDS. High HMGB1/suPAR expression might be linked to poor prognosis. Conclusion: Serum HMGB1/suPAR levels might aid diagnosis and predict poor prognosis of septic patients with ARDS.

The impact of ethnic background on ICU care and outcome in sepsis and septic shock - A retrospective multicenter analysis on 17,949 patients

BACKGROUND

Previous studies have been inconclusive about racial disparities in sepsis. This study evaluated the impact of ethnic background on management and outcome in sepsis and septic shock.

METHODS

This analysis included 17,146 patients suffering from sepsis and septic shock from the multicenter eICU Collaborative Research Database. Generalized estimated equation (GEE) population-averaged models were used to fit three sequential regression models for the binary primary outcome of hospital mortality.

RESULTS

Non-Hispanic whites were the predominant group (n = 14,124), followed by African Americans (n = 1,852), Hispanics (n = 717), Asian Americans (n = 280), Native Americans (n = 146) and others (n = 830). Overall, the intensive care treatment and hospital mortality were similar between all ethnic groups. This finding was concordant in patients with septic shock and persisted after adjusting for patient-level variables (age, sex, mechanical ventilation, vasopressor use and comorbidities) and hospital variables (teaching hospital status, number of beds in the hospital).

CONCLUSION

We could not detect ethnic disparities in the management and outcomes of critically ill septic patients and patients suffering from septic shock. Disparate outcomes among critically ill septic patients of different ethnicities are a public health, rather than a critical care challenge.

A Hemodynamic Echocardiographic Evaluation Predicts Prolonged Mechanical Ventilation in Septic Patients: A Pilot Study

Prolonged mechanical ventilation (PMV) is common among critically ill septic patients and leads to serious adverse effects. Transthoracic echocardiography (TTE) is an efficient tool for the assessment of septic shock. Our study investigated the relationship between TTE parameters and PMV in mechanically ventilated septic shock patients. TTE was performed in the first 24 h of intensive care unit admission, acquiring data on cardiac output (CO), cardiac index (CI), s' wave (s'), E wave (E), e' wave (e') and E/e' ratio. We compared data on patients who met the criteria for PMV with data on patients who did not. Sixty-four patients were included, 26 of whom met the criteria for PMV. CO, CI and s' were higher in patients who required PMV (5.49 vs. 4.20, p = 0.02; 2.95 vs. 2.34, p = 0.04; and 12.56 vs. 9.81, p = 0.01, respectively). CI correlated with s' (r = 0.37, p < 0.01). The areas under the receiver operating characteristic curves for CO, CI and s' in assessing the need for PMV were, respectively, 0.7 (fair results), 0.69 and 0.68 (poor results). Despite a lack of a prognostic model, the observed differences suggest that hemodynamic TTE could provide information on the risk of PMV in septic shock.

Definition, Incidence, and Epidemiology of Pediatric Acute Respiratory Distress Syndrome: From the Second Pediatric Acute Lung Injury Consensus Conference

OBJECTIVES

In 2015, the Pediatric Acute Lung Injury Consensus Conference (PALICC) provided the first pediatric-specific definitions for acute respiratory distress syndrome (pediatric acute respiratory distress syndrome [PARDS]). These definitions have since been operationalized in cohort and interventional PARDS studies. As substantial data have accrued since 2015, we have an opportunity to assess the construct validity and utility of the initial PALICC definitions. Therefore, the Second PALICC (PALICC-2) brought together multiple PARDS experts and aimed to identify and summarize relevant evidence related to the definition and epidemiology of PARDS and create modifications to the definition of PARDS.

DATA SOURCES

MEDLINE (Ovid), Embase (Elsevier), and CINAHL Complete (EBSCOhost).

STUDY SELECTION

We included studies of subjects with PARDS, or at risk for PARDS, excluding studies pertaining primarily to adults except as specified for identifying age-specific cutoffs.

DATA EXTRACTION

Title/abstract review, full-text review, and data extraction using a standardized data collection form.

DATA SYNTHESIS

The Grading of Recommendations Assessment, Development, and Evaluation approach was used to identify and summarize evidence and develop recommendations. A total of 97 studies were identified for full-text extraction addressing distinct aspects of the PARDS definition, including age, timing, imaging, oxygenation, modes of respiratory support, and specific coexisting conditions. Data were assessed in a Patient/Intervention/Comparator/Outcome format when possible, and formally summarized for effect size, risk, benefit, feasibility of implementation, and equity. A total of 17 consensus-based definition statements were made that update the definition of PARDS, as well as the related diagnoses of "Possible PARDS" and "At-Risk for PARDS." These statements are presented alongside a summary of the relevant epidemiology.

CONCLUSIONS

We present updated, data-informed consensus statements on the definition for PARDS and the related diagnoses of "Possible PARDS" and "At-Risk for PARDS."

Neutrophil activation and neutrophil extracellular traps (NETs) in COVID-19 ARDS and immunothrombosis

Acute respiratory distress syndrome (ARDS) is an acute inflammatory condition with a dramatic increase in incidence since the beginning of the coronavirus disease 19 (COVID-19) pandemic. Neutrophils play a vital role in the immunopathology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by triggering the formation of neutrophil extracellular traps (NETs), producing cytokines including interleukin-8 (CXCL8), and mediating the recruitment of other immune cells to regulate processes such as acute and chronic inflammation, which can lead to ARDS. CXCL8 is involved in the recruitment, activation, and degranulation of neutrophils, and therefore contributes to inflammation amplification and severity of disease. Furthermore, activation of neutrophils also supports a prothrombotic phenotype, which may explain the development of immunothrombosis observed in COVID-19 ARDS. This review aims to describe hyperinflammatory ARDS due to SARS-CoV-2 infection. In addition, we address the critical role of polymorphonuclear neutrophils, inflammatory cytokines, and the potential targeting of CXCL8 in treating the hyperinflammatory ARDS population.

CORRELATION BETWEEN RED BLOOD CELL DISTRIBUTION WIDTH-TO-PLATELET RATIO AND MORTALITY IN PATIENTS WITH ACUTE RESPIRATORY DISTRESS SYNDROME: A RETROSPECTIVE COHORT STUDY

ABSTRACT

Background: This study aims to assess the prognostic value of red blood cell distribution width-to-platelet ratio (RPR) in acute respiratory distress syndrome (ARDS) patients. Methods: The data collected from 540 ARDS patients from 2001 to 2012 were obtained from the Medical Information Mart for Intensive Care III Database. The 28-day all-cause mortality risk was considered as the primary outcome parameter, and the secondary outcomes were 60- and 90-day all-cause mortality. The association between RPR (≥0.19 vs. <0.19) and mortality was assessed by Cox proportional hazards models, and potential nonlinear associations were assessed by restricted cubic spline regression analysis. Results: The 28-day all-cause mortality was 22.4%. Among the 121 deaths, 92 (20.0%) presented with an RPR <0.19, and 29 patients had RPR ≥0.19 ( P < 0.001). The 60- and 90-day all-cause mortality was 27% and 28.7%, respectively. After adjusting for the relevant factors in the multivariate model, RPR ≥0.19 was independently correlated with the 28-day all-cause mortality (hazard ratio, 2.74; 95% confidence interval, 1.46-5.15; P = 0.002). There was no nonlinear relationship between RPR and the risk of 28-day all-cause mortality ( P for overall association <0.001, P for nonlinear = 0.635). Similar results were observed for both the pneumonia and nonpneumonia subgroups and sensitivity analyses. Conclusions: The data promote the use of RPR as a valuable prognostic indicator for ARDS patients.

New Insights into Clinical and Mechanistic Heterogeneity of the Acute Respiratory Distress Syndrome: Summary of the Aspen Lung Conference 2021

Clinical and molecular heterogeneity are common features of human disease. Understanding the basis for heterogeneity has led to major advances in therapy for many cancers and pulmonary diseases such as cystic fibrosis and asthma. Although heterogeneity of risk factors, disease severity, and outcomes in survivors are common features of the acute respiratory distress syndrome (ARDS), many challenges exist in understanding the clinical and molecular basis for disease heterogeneity and using heterogeneity to tailor therapy for individual patients. This report summarizes the proceedings of the 2021 Aspen Lung Conference, which was organized to review key issues related to understanding clinical and molecular heterogeneity in ARDS. The goals were to review new information about ARDS phenotypes, to explore multicellular and multisystem mechanisms responsible for heterogeneity, and to review how best to account for clinical and molecular heterogeneity in clinical trial design and assessment of outcomes. The report concludes with recommendations for future research to understand the clinical and basic mechanisms underlying heterogeneity in ARDS to advance the development of new treatments for this life-threatening critical illness.

The Impact of Chronic Medical Conditions on Mortality in Acute Respiratory Distress Syndrome

PURPOSE

To examine the impact of chronic comorbidities on mortality in Acute Respiratory Distress Syndrome (ARDS).

MATERIALS AND METHODS

Retrospective cohort study of adults with ARDS (ICD-10-CM code J80) from the National Inpatient Sample between January, 2016 and December, 2018. For the primary outcome of mortality, we conducted weighted logistic regression adjusting for factors identified on univariate analysis as potentially significant or differing between the two groups at baseline. We used negative binomial regression adjusting for the same comorbidities to identify risk factors for longer length of stay (LOS) among ARDS survivors.

RESULTS

After exclusions, 1046 records were analyzed (3355 ARDS survivors and 1875 non-survivors.) The comorbidities examined included hypertension, diabetes mellitus, obesity, hypothyroidism, alcohol and drug use, chronic kidney disease (CKD), cardiovascular disease, chronic liver disease, chronic pulmonary disease and malignancy. In multivariate analysis, we found that malignancy (OR 2.26, 95% CI 1.84-2.78, p < 0.001), cardiovascular disease (OR 1.54, 95% CI 1.23-1.92, p < 0.001), and CKD (OR 1.75, 95% CI 1.22-2.50, p  =  0.002) increased the risk of death. In interaction analyses, cardiovascular disease combined with either malignancy or CKD conferred higher odds of death compared to either risk factor alone.

CONCLUSIONS

The comorbidity of malignancy confers the most reliable risk of poor outcomes in ARDS with higher odds of hospital death and a simultaneous association with longer hospital LOS among survivors.

Classic Signaling Pathways in Alveolar Injury and Repair Involved in Sepsis-Induced ALI/ARDS: New Research Progress and Prospect

Sepsis is a common critical clinical disease with high mortality that can cause approximately 10 million deaths worldwide each year. Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a common clinical complication of sepsis, which occurs primarily as diffuse alveolar injury, hypoxemia, and respiratory distress. The mortality rate of ALI/ARDS is as high as 30%-40%, which greatly endangers human health. Due to the unclear pathogenesis of ALI/ARDS, its treatment is still a worldwide problem. At present, clinical treatment mainly relies on lung-protective ventilation, prone position ventilation, and fluid management. However, there is a lack of effective and specific treatment measures. In recent years, domestic and foreign scholars have committed to basic research on ALI/ARDS, trying to further clarify its pathogenesis and find new targets and methods for the treatment of ALI/ARDS. In this review, we summarize the signaling pathways related to alveolar injury and repair in sepsis-induced ALI/ARDS and their latest research progress. They include the NF-κB, JAK2/STAT3, mitogen-activated protein kinase (MAPK), mTOR, and Notch signaling pathways. Understanding the molecular mechanisms of these signaling pathways in sepsis-induced ALI/ARDS may provide new targets and ideas for the clinical treatment of this disease.

Extracellular vesicles as mediators and markers of acute organ injury: current concepts

Due to the continued high incidence and mortality rate worldwide, there is a need to develop new strategies for the quick, precise, and valuable recognition of presenting injury pattern in traumatized and poly-traumatized patients. Extracellular vesicles (EVs) have been shown to facilitate intercellular communication processes between cells in close proximity as well as distant cells in healthy and disease organisms. miRNAs and proteins transferred by EVs play biological roles in maintaining normal organ structure and function under physiological conditions. In pathological conditions, EVs change the miRNAs and protein cargo composition, mediating or suppressing the injury consequences. Therefore, incorporating EVs with their unique protein and miRNAs signature into the list of promising new biomarkers is a logical next step. In this review, we discuss the general characteristics and technical aspects of EVs isolation and characterization. We discuss results of recent in vitro, in vivo, and patients study describing the role of EVs in different inflammatory diseases and traumatic organ injuries. miRNAs and protein signature of EVs found in patients with acute organ injury are also debated.

Utilization of Brain Tissue Oxygenation Monitoring and Association with Mortality Following Severe Traumatic Brain Injury

BACKGROUND

The aim of this study was to describe the utilization patterns of brain tissue oxygen (PbtO₂) monitoring following severe traumatic brain injury (TBI) and determine associations with mortality, health care use, and pulmonary toxicity.

METHODS

We conducted a retrospective cohort study of patients from United States trauma centers participating in the American College of Surgeons National Trauma Databank between 2008 and 2016. We examined patients with severe TBI (defined by admission Glasgow Coma Scale score ≤ 8) over the age of 18 years who survived more than 24 h from admission and required intracranial pressure (ICP) monitoring. The primary exposure was PbtO₂ monitor placement. The primary outcome was hospital mortality, defined as death during the hospitalization or discharge to hospice. Secondary outcomes were examined to determine the association of PbtO₂ monitoring with health care use and pulmonary toxicity and included the following: (1) intensive care unit length of stay, (2) hospital length of stay, and (3) development of acute respiratory distress syndrome (ARDS). Regression analysis was used to assess differences in outcomes between patients exposed to PbtO₂ monitor placement and those without exposure by using propensity weighting to address selection bias due to the nonrandom allocation of treatment groups and patient dropout.

RESULTS

A total of 35,501 patients underwent placement of an ICP monitor. There were 1,346 (3.8%) patients who also underwent PbtO₂ monitor placement, with significant variation regarding calendar year and hospital. Patients who underwent placement of a PbtO₂ monitor had a crude in-hospital mortality of 31.1%, compared with 33.5% in patients who only underwent placement of an ICP monitor (adjusted risk ratio 0.84, 95% confidence interval 0.76-0.93). The development of the ARDS was comparable between patients who underwent placement of a PbtO₂ monitor and patients who only underwent placement of an ICP monitor (9.2% vs. 9.8%, adjusted risk ratio 0.89, 95% confidence interval 0.73-1.09).

CONCLUSIONS

PbtO₂ monitor utilization varied widely throughout the study period by calendar year and hospital. PbtO₂ monitoring in addition to ICP monitoring, compared with ICP monitoring alone, was associated with a decreased in-hospital mortality, a longer length of stay, and a similar risk of ARDS. These findings provide further guidance for clinicians caring for patients with severe TBI while awaiting completion of further randomized controlled trials.

Inpatient Mortality Among Patients With Acute Respiratory Distress Syndrome at ECMO and Non-ECMO Centers in the United States

BACKGROUND

A 2009 randomized control trial found patients with severe acute respiratory distress syndrome (ARDS) who transferred to an extra-corporeal membrane oxygenation therapy (ECMO) center had better survival, even if they did not receive ECMO. This study aimed to use a national US database to determine if care at ECMO centers offer a survival advantage in patients with ARDS with mechanical ventilation only.

METHODS

Hospitalizations of patients 18-64 years old who had ARDS and mechanical ventilation in the 2010-2016 Health care Cost and Utilization Project National Readmission Database were included. ECMO centers performed at least 1 veno-venous ECMO hospitalization annually; or >5, >20, and >50 on sensitivity analysis. Multivariable logistic regression compared inpatient mortality, after adjusting for timing of hospitalization, patient demographics, comorbidities, and hospital characteristics.

RESULTS

Of the 1 224 447 ARDS hospitalizations and mechanical ventilation, 41% were at ECMO centers. ECMO centers were more likely to be larger, private, non-profit, teaching hospitals. ARDS at admission was more common at non-ECMO centers (31% vs 23%, P < .0001); however, other patient demographics and comorbidities did not differ. After adjustment, no difference in inpatient mortality was seen between ECMO and non-ECMO centers (OR 0.99, 95% CI: 0.97, 1.02). This relationship did not change in sensitivity analyses.

DISCUSSION

Adult patients with ARDS requiring mechanical ventilation may not have improved outcomes if treated at an ECMO center and suggest that early transfer of all ARDS patients to ECMO centers may not be warranted. Further evaluation of ECMO center volume and illness severity is needed.

Clinical Utility of Surgical Lung Biopsy for Patients with Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

BACKGROUND

Surgical lung biopsy (SLB) is performed in patients with acute respiratory distress syndrome (ARDS); however, its clinical utility remains unclear.

OBJECTIVES

We categorized the pathological diagnoses and investigated the predictive value for short-term mortality.

METHOD

Three electronic databases (MEDLINE, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov) were searched for the included studies. The QUADAS-2 was used to evaluate the risk of bias and its applicability. The types and populations of pathological diagnoses were investigated. The pooled sensitivity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR) were estimated at a fixed specificity. Hierarchical summary receiver operating characteristic curves were drawn.

RESULTS

A total of 16 studies that enrolled 758 patients were included. The pathological diagnoses were as follows: diffuse alveolar damage (DAD) 29.9%; infection 24.7%; interstitial lung disease 17.2%; malignancy 3.6%; cardiovascular disease 3.6%; drug toxicity 2.3%; connective tissue disease 2.2%; allergic disease 1.1%; and nonspecific diagnosis 15.4%. To predict short-term mortality, 13 studies that enrolled 613 patients used DAD as an index test and recorded a mortality rate of 56.9% (349 of 613 patients). A total of 3 studies that used index tests other than DAD were excluded. The pooled sensitivity, fixed specificity, LR+, LR-, and DOR were 0.46 (95% confidence interval [CI]: 0.29-0.56), 0.69, 1.48 (95% CI: 0.92-1.81), 0.78 (95% CI: 0.63-1.03), and 1.90 (95% CI: 0.89-2.86), respectively.

CONCLUSIONS

SLB is unlikely to provide a specific diagnosis and should not be recommended for confirming DAD or predicting ARDS prognosis.

Effects of aerobic exercise on lipopolysaccharide-induced experimental acute lung injury in the animal model of type 1 diabetes mellitus

NEW FINDINGS

What is the central question of this study? We evaluated the effects of diabetes and exercise on lipopolysaccharide-induced acute lung injury. By providing a comprehensive analysis of redox status, blood gases and histological parameters, we aimed to contribute to the ongoing debate in the literature. What are the main findings and its importance? We demonstrated the preventive effect of exercise, but diabetes did not alter the severity of acute lung injury.

ABSTRACT

Acute lung injury (ALI) is a life-threatening respiratory condition. Diabetes (DM) is a metabolic disease characterized by hyperglycaemia. There is an ongoing debate concerning whether there is a protective effect of diabetes in ALI. Exercise is a special type of physical activity that has numerous beneficial effects. The aim of our study was to investigate the effects of diabetes and exercise on the prognosis of ALI. Male Wistar albino rats were divided into two groups (sedentary and exercise). Both groups were divided into four subgroups: Control, ALI, DM, DM+ALI (n = 6 each). Diabetes was induced by injection of streptozotocin (50 mg/kg i.p.). The maximal exercise capacity was determined with the incremental load test. Animals were exercised on a treadmill for 45 min at 70% of maximal exercise capacity, 5 days a week for 12 weeks. Acute lung injury was induced by intratracheal injection of lipopolysaccharide (100 μg/100 g body weight) 24 h before the end of the experiment. We performed arterial blood gas analysis. Redox status was measured in both plasma and lung tissue. Malondialdehyde and 8-hydroxy-2'-deoxyguanosine levels were measured in lung tissue. Lung tissue was evaluated histologically. Acute lung injury caused significant damage in the lung tissue, which was verified histologically, with an increase in oxidative stress parameters. Exercise prevented the lung damage induced by ALI and reduced oxidative stress in the lung tissue. Diabetes did not alter the magnitude of damage done by ALI. Exercise showed a protective effect against DM and ALI in rats. The effect of DM was insignificant for the prognosis of ALI.

Prevalence, risk, and outcome of deep vein thrombosis in acute respiratory distress syndrome

BACKGROUND

Few data exist on deep vein thrombosis (DVT) in patients with acute respiratory distress syndrome (ARDS), a group of heterogeneous diseases characterized by acute hypoxemia.

STUDY DESIGN AND METHODS

We retrospectively enrolled 225 adults with ARDS admitted to the Beijing Chao-Yang Hospital and the First Affiliated Hospital of Shandong First Medical University between 1 January 2015 and 30 June 2020. We analyzed clinical, laboratory, and echocardiography data for groups with and without DVT and for direct (pulmonary) and indirect (extrapulmonary) ARDS subgroups.

RESULTS

Ninety (40.0%) patients developed DVT. Compared with the non-DVT group, patients with DVT were older, had lower serum creatinine levels, lower partial pressure of arterial oxygen/fraction of inspired oxygen, higher serum procalcitonin levels, higher Padua prediction scores, and higher proportions of sedation and invasive mechanical ventilation (IMV). Multivariate analysis showed an association between age, serum creatinine level, IMV, and DVT in the ARDS cohort. The sensitivity and specificity of corresponding receiver operating characteristic curves were not inferior to those of the Padua prediction score and the Caprini score for screening for DVT in the three ARDS cohorts. Patients with DVT had a significantly lower survival rate than those without DVT in the overall ARDS cohort and in the groups with direct and indirect ARDS.

CONCLUSIONS

The prevalence of DVT is high in patients with ARDS. The risk factors for DVT are age, serum creatinine level, and IMV. DVT is associated with decreased survival in patients with ARDS.

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.

A Five-Genes Based Diagnostic Signature for Sepsis-Induced ARDS

Background: Acute respiratory distress syndrome (ARDS) is a frequent and serious complication of sepsis without specific and sensitive diagnostic signatures.

Methods: The mRNA profiles, including 60 blood samples with sepsis-induced ARDS and 86 blood samples with sepsis alone, were obtained from the Gene Expression Omnibus (GEO). The differently expressed genes (DEGs) were analyzed by limma package of R language. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were carried out using the clusterProfiler package of R. Eventually, multivariate logistic regression model was established through the glm function of R, and support vector machine (SVM) model was constructed via the e1071 package of R.

Results: A total of 242 DEGs in GSE32707 and 102 DEGs in GSE66890 were identified. Notably, five genes exhibited significant differences between the two datasets and were considered to be closely associated with the occurrence of ARDS induced by sepsis. Furthermore, functional enrichment analysis based on the DEGs showed there were 80 overlapped GO terms and one KEGG pathway which were significantly enriched in the two datasets. The logistic regression model and SVM model constructed could efficiently distinguish sepsis patients with or without ARDS.

Conclusion: In brief, our study suggested that NKG7, SPTA1, FGL2, RGS2, and IFI27 might be potential diagnostic signatures for sepsis-induced ARDS, which contributed to the future exploration in mechanism of ARDS occurrence and development.

July Effect on Mortality and Complications in Patients With ARDS in US Teaching Hospitals

BACKGROUND

Each July, teaching hospitals in the United States experience an influx of new resident and fellow physicians. It has been theorized that this occurrence may be associated with increased patient mortality, complication rates, and health care resource use, a phenomenon known as the "July effect."

OBJECTIVE

To assess the existence of a July effect in clinical outcomes of patients with acute respiratory distress syndrome (ARDS) receiving mechanical ventilation in the intensive care unit in US teaching hospitals.

METHODS

The National Inpatient Sample database was queried for all adult patients with ARDS who received mechanical ventilation from 2012 to 2014. Using a multivariate difference-in-differences (DID) model, differences in mortality, ventilator-associated pneumonia, iatrogenic pneumothorax, central catheter-associated bloodstream infection, and Clostridium difficile infection were compared between teaching and nonteaching hospitals during April-May and July-August.

RESULTS

There were 70 535 and 43 175 hospitalizations meeting study criteria in teaching and nonteaching hospitals, respectively. Multivariate analyses revealed no differential effect on the rates of all-cause inpatient mortality (DID, 0.66; 95% CI, -0.42 to 1.75), C difficile infection (DID, 0.29; 95% CI, -0.19 to 0.78), central catheter-associated bloodstream infection (DID, 0.14; 95% CI, -0.04 to 0.33), iatrogenic pneumothorax (DID, 0.00; 95% CI, -0.25 to 0.24), ventilator-associated pneumonia (DID, 0.22; 95% CI, -0.05 to 0.49), and any complication (DID, 0.60; 95% CI, -0.01 to 1.20) for July-August versus April-May in teaching hospitals compared with nonteaching hospitals.

CONCLUSION

This study did not show a differential July effect on mortality outcomes and complication rates in ARDS patients receiving mechanical ventilation in teaching hospitals compared with nonteaching hospitals.

Prolonged Prehospital Time is a Risk Factor for Pneumonia in Trauma (the PRE-TRIP study): A Retrospective Analysis of the United States National Trauma Data Bank

BACKGROUND

Although multiple risk factors for development of pneumonia in patients with trauma sustained in a motor vehicle accident have been studied, the effect of prehospital time on pneumonia incidence post-trauma is unknown.

RESEARCH QUESTION

Is prolonged prehospital time an independent risk factor for pneumonia?

STUDY DESIGN AND METHODS

We retrospectively analyzed prospectively collected clinical data from 806,012 motor vehicle accident trauma incidents from the roughly 750 trauma hospitals contributing data to the National Trauma Data Bank between 2010 and 2016.

RESULTS

Prehospital time was independently associated with development of pneumonia post-motor vehicle trauma (p < 0.001). This association was primarily driven by patients with low Glasgow Coma Scale scores. Post-trauma pneumonia was uncommon (1.5% incidence) but was associated with a significant increase in mortality (p < 0.001, 4.3% mortality without pneumonia vs. 12.1% mortality with pneumonia). Other pneumonia risk factors included age, sex, race, primary payor, trauma center teaching status, bed size, geographic region, intoxication, comorbid lung disease, steroid use, lower Glasgow Coma Scale score, higher Injury Severity Scale score, blood product transfusion, chest trauma, and respiratory burns.

INTERPRETATION

Increased prehospital time is an independent risk factor for development of pneumonia and increased mortality in patients with trauma caused by a motor vehicle accident. Although prehospital time is often not modifiable, its recognition as a pneumonia risk factor is important as prolonged prehospital time may need to be considered in subsequent decision making.

CLINICAL TRIAL REGISTRATION

Not applicable.

Trends and Geographic Variation in Acute Respiratory Failure and ARDS Mortality in the United States

BACKGROUND

Despite numerous advances in the understanding of the pathophysiology, progression, and management of acute respiratory failure (ARF) and ARDS, limited contemporary data are available on the mortality burden of ARF and ARDS in the United States.

RESEARCH QUESTION

What are the contemporary trends and geographic variation in ARF and ARDS-related mortality in the United States?

STUDY DESIGN AND METHODS

A retrospective analysis of the National Center for Health Statistics' nationwide mortality data was conducted to assess the ARF and ARDS-related mortality trends from 2014 through 2018 and the geographic distribution of ARF and ARDS-related deaths in 2018 for all American residents. Piecewise linear regression was used to evaluate the trends in age-adjusted mortality rates (AAMRs) in the overall population and various demographic subgroups of age, sex, race, urbanization, and region.

RESULTS

Among 1,434,349 ARF-related deaths and 52,958 ARDS-related deaths during the study period, the AAMR was highest in older individuals (≥ 65 years), non-Hispanic Black people, and those living in the nonmetropolitan region. The AAMR for ARF-related deaths (per 100,000 people) increased from 74.9 (95% CI, 74.6-75.2) in 2014 to 85.6 (95% CI, 85.3-85.9) in 2018 (annual percentage change [APC], 3.4 [95% CI, 2.2-4.6]; Ptrend = .003). The AAMR (per 100,000 people) for ARDS-related deaths was 3.2 (95% CI, 3.2-3.3) in 2014 and 3.0 (95% CI, 3.0-3.1 in 2018; APC, -0.9 [95% CI, -5.4 to 3.8]; Ptrend = .56). The observed increase in rates for ARF mortality was consistent across the subgroups of age, sex, race or ethnicity, urbanization status, and geographical region (Ptrend < .05 for all). The AAMR (per 100,000 people) for ARF (91.3 [95% CI, 90.8-91.8]) and ARDS-related mortality (3.3 [95% CI, 3.2-3.4]) in 2018 were highest in the South.

INTERPRETATION

The ARF-related mortality increased at approximately 3.4% annually, and ARDS-related mortality showed a lack of decline in the last 5 years. These data contextualize important health information to guide priorities for research, clinical care, and policy, especially during the coronavirus disease 2019 pandemic in the United States.

National incidence rate and related mortality for acute respiratory distress syndrome in France

INTRODUCTION

Despite many efforts to improve mechanical ventilation strategies and the use of rescue strategies, ARDS-related mortality remains high. The primary objective of this study was to determine the incidence and 90-day mortality of ARDS patients admitted to all French ICUs following the introduction of the Berlin definition of ARDS.

PATIENTS AND METHODS

The data source for this nationwide cohort study was the French national hospital database (Programme de Médicalisation des Systèmes d'Information (PMSI)), which systematically collects administrative and medical information related to all patients hospitalised and hospital stays. Patient-level data were obtained from the PMSI database for all patients admitted to an ICU from the 1^st of January 2017, through the 31^st of December 2017. The inclusion criteria were as follows: ICU patients ≥ 18 years old with at least one International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10) diagnosis code of J80 (ARDS), either as a primary diagnosis or a secondary diagnosis, during their ICU stay.

RESULTS

A total of 12,846 ICU adult patients with ARDS were included. The crude incidence of ARDS was 24.6 per 100,000 person-years, varying with age from 6.7 per 100,000 person-years for those 18 through 40 years of age to 51.9 per 100,000 person-years for those 68 through 76 years of age. The in-hospital mortality rate was 51.1%. Day-90 mortality (day-1 being the ICU admission) was 51.2% and increased with age from 29.0% for patients 18 through 40 years of age to 69.3% for patients 77 years of age or older (p < 0.001). Only 53.9% of the survivors were transferred home directly after hospital discharge.

CONCLUSIONS

The incidence and mortality of ARDS in adults in France are higher than that generally reported in other countries.

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.

Prone Positioning in Patients With Acute Respiratory Distress Syndrome and Other Respiratory Conditions: Challenges, Complications, and Solutions

Acute respiratory distress syndrome (ARDS) and respiratory failure are characterized by hypoxemia, i.e., low levels of blood oxygen. Infections such as influenza and COVID-19 can lead to ARDS or respiratory failure. Treatment is through supportive measures. In severe cases, patients receive oxygen through a ventilator and, when appropriate, are placed in a prone position for an extended period. A retrospective review of events submitted to the Pennsylvania Patient Safety Reporting System (PA-PSRS) identified 98 prone position–related events in patients with ARDS, respiratory failure, distress, and pneumonia from January 1, 2010, through June 30, 2020; 30 events were associated with COVID-19. Skin integrity injuries accounted for 83.7% (82 of 98) of the events. The remaining events, 16.3% (16 of 98), involved unplanned extubations, cardiac arrests, displaced lines, enteral feedings, medication errors, a dental issue, and posterior ischemic optic neuropathy.

Experimental pancreatitis is characterized by rapid T cell activation, Th2 differentiation that parallels disease severity, and improvement after CD4+ T cell depletion

BACKGROUND

Acute pancreatitis is a gastrointestinal disorder of high incidence resulting in life threatening complications in up to 20% of patients. Its severe form is characterized by an extensive and systemic immune response. We investigated the role of the adaptive immune response in two experimental models of pancreatitis.

METHODS

In C57BI/6-mice mild pancreatitis was induced by 8-hourly injections of caerulein and severe pancreatitis by additional, partial pancreatic duct ligation. T-cell-activation was determined by flow-cytometry of CD25/CD69, T-cell-differentiation by nuclear staining of the transcription-factors Tbet, Gata3 and Foxp3. In vivo CD4⁺ T-cells were depleted using anti-CD4 antibody. Disease severity was determined by histology, serum amylase and lipase activities, lung MPO and serum cytokine levels (IL-6, TNFα, IL-10).

RESULTS

In both models T-cells were activated. Th1-differentiation (Tbet) was absent during pancreatitis but we detected a pronounced Th2/Treg (Gata3/Foxp3) response which paralleled disease severity in both models. The complete depletion of CD4⁺ T-cells via anti-CD4 antibody, surprisingly, reduced disease severity significantly, as well as granulocyte infiltration and pro- and anti-inflammatory cytokine levels. Co-incubation of acini and T-cells did not lead to T-cell-activation by acinar cells but to acinar damage by T-cells. During pancreatitis no significant T-cell-infiltration into the pancreas was observed.

CONCLUSION

T cells orchestrate the early local as well as the systemic immune responses in pancreatitis and are directly involved in organ damage. The Th2 response appears to increase disease severity, rather than conferring an immunological protection.

[Electroacupuncture protects septic rats from acute lung injury through the JAK1/STAT3 pathway]

OBJECTIVE

To explore the protective effect of electroacupuncture against acute lung injury (ALI) in septic rats and explore the mechanism.

METHODS

Sixty male SD rats were randomly divided into cecal ligation and puncture (CLP)-induced sepsis group (n=45) and sham operation group (n=15; with laparotomy but without CLP). The rat models of sepsis were randomized into ALI group (n=15) without further treatment, ALI + SEA group (n=15) treated with electroacupuncture at the point far from the Zusanli acupoint for 30 min, and ALI + EA group (n=15) with electroacupuncture at Zusanli with identical frequency, intensity and duration of electrical stimulation. All the rats were sacrificed at 12 h after CLP for measurement of the weight and the wet/dry weight (W/D) ratio of the lungs. Pathological changes of the lung tissues were examined using HE staining, and the contents of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the homogenate of the lung tissues were detected using enzyme-linked immunosorbent assay (ELISA). TUNEL staining was used to detect the apoptotic cells, and the expressions of Bax, caspase-3 and the important proteins in the JAK1/STAT3 signaling pathway (JAK1 and STAT3) were detected with Western blotting.

RESULTS

Compared with those in the sham operation group, the rats in ALI group showed obvious lung pathologies with significantly increased lung W/D ratio (P < 0.01), pulmonary expressions of TNF-α and IL-6 (P < 0.01), and obvious up-regulation of JAK1, STAT3, caspase-3, and Bax expressions (P < 0.01); similar changes were also observed in ALI+SEA group (P > 0.05). Compared with those in ALI+SEA group, the rats in ALI+EA group showed significantly milder lung pathologies, lowered lung W/D ratio (P < 0.01) and decreased pulmonary expressions of TNF-α, IL-6, JAK1, STAT3, caspase-3 and Bax (P < 0.01).

CONCLUSIONS

Electroacupuncture can inhibit the release of inflammatory mediators and cell apoptosis via the JAK1/STAT3 pathway to reduce lung injuries in septic rats.

Machine Learning Methods to Predict Acute Respiratory Failure and Acute Respiratory Distress Syndrome

Acute respiratory failure (ARF) is a common problem in medicine that utilizes significant healthcare resources and is associated with high morbidity and mortality. Classification of acute respiratory failure is complicated, and it is often determined by the level of mechanical support that is required, or the discrepancy between oxygen supply and uptake. These phenotypes make acute respiratory failure a continuum of syndromes, rather than one homogenous disease process. Early recognition of the risk factors for new or worsening acute respiratory failure may prevent that process from occurring. Predictive analytical methods using machine learning leverage clinical data to provide an early warning for impending acute respiratory failure or its sequelae. The aims of this review are to summarize the current literature on ARF prediction, to describe accepted procedures and common machine learning tools for predictive tasks through the lens of ARF prediction, and to demonstrate the challenges and potential solutions for ARF prediction that can improve patient outcomes.

Intravenous sulforhodamine B reduces alveolar surface tension, improves oxygenation, and reduces ventilation injury in a respiratory distress model

In the neonatal respiratory distress syndrome (NRDS) and acute respiratory distress syndrome (ARDS), mechanical ventilation supports gas exchange but can cause ventilation-induced lung injury (VILI) that contributes to high mortality. Further, surface tension, T, should be elevated and VILI is proportional to T. Surfactant therapy is effective in NRDS but not ARDS. Sulforhodamine B (SRB) is a potential alternative T-lowering therapeutic. In anesthetized male rats, we injure the lungs with 15 min of 42 mL/kg tidal volume, V_T, and zero end-expiratory pressure ventilation. Then, over 4 h, we support the rats with protective ventilation-V_T of 6 mL/kg with positive end-expiratory pressure. At the start of the support period, we administer intravenous non-T-altering fluorescein (targeting 27 µM in plasma) without or with therapeutic SRB (10 nM). Throughout the support period, we increase inspired oxygen fraction, as necessary, to maintain >90% arterial oxygen saturation. At the end of the support period, we euthanize the rat; sample systemic venous blood for injury marker ELISAs; excise the lungs; combine confocal microscopy and servo-nulling pressure measurement to determine T in situ in the lungs; image fluorescein in alveolar liquid to assess local permeability; and determine lavage protein content and wet-to-dry ratio (W/D) to assess global permeability. Lungs exhibit focal injury. Surface tension is elevated 72% throughout control lungs and in uninjured regions of SRB-treated lungs, but normal in injured regions of treated lungs. SRB administration improves oxygenation, reduces W/D, and reduces plasma injury markers. Intravenous SRB holds promise as a therapy for respiratory distress.NEW & NOTEWORTHY Sulforhodmaine B lowers T in alveolar edema liquid. Given the problematic intratracheal delivery of surfactant therapy for ARDS, intravenous SRB might constitute an alternative therapeutic. In a lung injury model, we find that intravenously administered SRB crosses the injured alveolar-capillary barrier thus reduces T specifically in injured lung regions; improves oxygenation; and reduces the degree of further lung injury. Intravenous SRB administration might help respiratory distress patients, including those with the novel coronavirus, avoid mechanical ventilation or, once ventilated, survive.

Phenotypes and personalized medicine in the acute respiratory distress syndrome

Although the acute respiratory distress syndrome (ARDS) is well defined by the development of acute hypoxemia, bilateral infiltrates and non-cardiogenic pulmonary edema, ARDS is heterogeneous in terms of clinical risk factors, physiology of lung injury, microbiology, and biology, potentially explaining why pharmacologic therapies have been mostly unsuccessful in treating ARDS. Identifying phenotypes of ARDS and integrating this information into patient selection for clinical trials may increase the chance for efficacy with new treatments. In this review, we focus on classifying ARDS by the associated clinical disorders, physiological data, and radiographic imaging. We consider biologic phenotypes, including plasma protein biomarkers, gene expression, and common causative microbiologic pathogens. We will also discuss the issue of focusing clinical trials on the patient's phase of lung injury, including prevention, administration of therapy during early acute lung injury, and treatment of established ARDS. A more in depth understanding of the interplay of these variables in ARDS should provide more success in designing and conducting clinical trials and achieving the goal of personalized medicine.

The Role of MicroRNAs in Acute Respiratory Distress Syndrome and Sepsis, From Targets to Therapies: A Narrative Review

Acute respiratory distress syndrome (ARDS) is a significant cause of morbidity and mortality in the intensive care unit (ICU) and is characterized by lung epithelial and endothelial cell injury, with increased permeability of the alveolar-capillary membrane, leading to pulmonary edema, severe hypoxia, and difficulty with ventilation. The most common cause of ARDS is sepsis, and currently, treatment of ARDS and sepsis has consisted mostly of supportive care because targeted therapies have largely been unsuccessful. The molecular mechanisms behind ARDS remain elusive. Recently, a number of microRNAs (miRNAs) identified through high-throughput screening studies in ARDS patients and preclinical animal models have suggested a role for miRNA in the pathophysiology of ARDS. miRNAs are small noncoding RNAs ranging from 18 to 24 nucleotides that regulate gene expression via inhibition of the target mRNA translation or by targeting complementary mRNA for early degradation. Unsurprisingly, some miRNAs that are differentially expressed in ARDS overlap with those important in sepsis. In addition, circulatory miRNA may be useful as biomarkers or as targets for pharmacologic therapy. This can be revolutionary in a syndrome that has neither a measurable indicator of the disease nor a targeted therapy. While there are currently no miRNA-based therapies targeted for ARDS, therapies targeting miRNA have reached phase II clinical trials for the treatment of a wide range of diseases. Further studies may yield a unique miRNA profile pattern that serves as a biomarker or as targets for miRNA-based pharmacologic therapy. In this review, we discuss miRNAs that have been found to play a role in ARDS and sepsis, the potential mechanism of how particular miRNAs may contribute to the pathophysiology of ARDS, and strategies for pharmacologically targeting miRNA as therapy.

Investigation of anti-inflammatory effects of oxygen nanobubbles in a rat hydrochloric acid lung injury model

Aim: To investigate the anti-inflammatory effect of oxygen nanobubbles (ONBs) in an acute lung injury rat model. Materials & methods: In a rat hydrochloric acid lung injury model, ONB fluid was administered intravenously in the ONB group (n = 6) and normal saline was administered in the control group (n = 6). 4 h later, arterial partial pressure of oxygen (PaO₂), mean arterial pressure and plasma inflammatory cytokines were measured. Results: There were no significant differences in the PaO₂, mean arterial pressure or TNF-α and IL-6 levels between the two groups. Conclusions: No anti-inflammatory effect could be confirmed at the present ONB dose in the rat model of acute lung injury.

The Impact of Aging in Acute Respiratory Distress Syndrome: A Clinical and Mechanistic Overview

Acute respiratory distress syndrome (ARDS) is associated with increased morbidity and mortality in the elderly population (≥65 years of age). Additionally, age is widely reported as a risk factor for the development of ARDS. However, the underlying pathophysiological mechanisms behind the increased risk of developing, and increased severity of, ARDS in the elderly population are not fully understood. This is compounded by the significant heterogeneity observed in patients with ARDS. With an aging population worldwide, a better understanding of these mechanisms could facilitate the development of therapies to improve outcomes in this population. In this review, the current clinical evidence of age as a risk factor and prognostic indicator in ARDS and the potential underlying mechanisms that may contribute to these factors are outlined. In addition, research on age-dependent treatment options and biomarkers, as well as future prospects for targeting these underlying mechanisms, are discussed.

Identification of atypical mitogen-activated protein kinase MAPK4 as a novel regulator in acute lung injury

Background

Acute lung injury (ALI) is a serious disease with highly morbidity and mortality that causes serious health problems worldwide. Atypical mitogen activated protein kinases (MAPKs) play critical roles in the development of tissues and have been proposed as promising therapeutic targets for various diseases. However, the potential role of atypical MAPKs in ALI remains elusive. In this study, we investigated the role of atypical MAPKs family member MAPK4 in ALI using LPS-induced murine ALI model.

Results

We found that MAPK4 deficiency mice exhibited prolonged survival time after LPS challenge, accompanied by alleviated pathology in lung tissues, decreased levels of pro-inflammatory cytokines and altered composition of immune cells in BALF. Furthermore, the transduction of related signaling pathways, including MK5, AKT, JNK, and p38 MAPK pathways, was reduced obviously in LPS-treated MAPK4^−/− mice. Notably, the expression of MAPK4 was up-regulated in lung tissues of ALI model, which was not related with MAPK4 promoter methylation, but negatively orchestrated by transcriptional factors NFKB1 and NR3C1. Further studies have shown that the expression of MAPK4 was also increased in LPS-treated macrophages. Meanwhile, MAPK4 deficiency reduced the expression of related pro-inflammatory cytokines in macrophage in response to LPS treatment. Finally, MAPK4 knockdown using shRNA pre-treatment could ameliorate the pathology of lung tissues and prolong the survival time of mice after LPS challenge.

Conclusions

Collectively, these findings reveal an important biological function of atypical MAPK in mediating the pathology of ALI, indicating that MAPK4 might be a novel potential therapeutic target for ALI treatment.

Sulforhodamine B and exogenous surfactant effects on alveolar surface tension under acute respiratory distress syndrome conditions

In the acute respiratory distress syndrome (ARDS), alveolar surface tension, T, may be elevated. Elevated T should increase ventilation-induced lung injury. Exogenous surfactant therapy, intended to lower T, has not reduced mortality. Sulforhodamine B (SRB) might, alternatively, be used to lower T. We test whether substances suspected of elevating T in ARDS raise T in the lungs and test the abilities of exogenous surfactant and SRB to reduce T. In isolated rat lungs, we micropuncture a surface alveolus and instill a solution of a purported T-raising substance: control saline, cell debris, secretory phospholipase A₂ (sPLA₂), acid, or mucins. We test each substance alone; with albumin, to model proteinaceous edema liquid; with albumin and exogenous surfactant; and with albumin and SRB. We determine T in situ in the lungs by combining servo-nulling pressure measurement with confocal microscopy and applying the Laplace relation. With control saline, albumin does not alter T, additional surfactant raises T, and additional SRB lowers T. The experimental substances, without or with albumin, raise T. Excepting under aspiration conditions, addition of surfactant or SRB lowers T. Exogenous surfactant activity is concentration and ventilation dependent. Sulforhodamine B, which could be delivered intravascularly, holds promise as an alternative therapeutic.NEW & NOTEWORTHY In the acute respiratory distress syndrome (ARDS), lowering surface tension, T, should reduce ventilation injury yet exogenous surfactant has not reduced mortality. We show with direct T determination in isolated lungs that substances suggested to elevate T in ARDS indeed raise T, and exogenous surfactant reduces T. Further, we extend our previous finding that sulforhodamine B (SRB) reduces T below normal in healthy lungs and show that SRB, too, reduces T under ARDS conditions.

Isolated Lung Perfusion in the Management of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is associated with high morbidity and mortality, and current management has a dramatic impact on healthcare resource utilization. While our understanding of this disease has improved, the majority of treatment strategies remain supportive in nature and are associated with continued poor outcomes. There is a dramatic need for the development and breakthrough of new methods for the treatment of ARDS. Isolated machine lung perfusion is a promising surgical platform that has been associated with the rehabilitation of injured lungs and the induction of molecular and cellular changes in the lung, including upregulation of anti-inflammatory and regenerative pathways. Initially implemented in an ex vivo fashion to evaluate marginal donor lungs prior to transplantation, recent investigations of isolated lung perfusion have shifted in vivo and are focused on the management of ARDS. This review presents current tenants of ARDS management and isolated lung perfusion, with a focus on how ex vivo lung perfusion (EVLP) has paved the way for current investigations utilizing in vivo lung perfusion (IVLP) in the treatment of severe ARDS.