Clinical Predictors of Hospital Mortality Differ Between Direct and Indirect ARDS

Establishment of a Predictive Model for Acute Respiratory Distress Syndrome in Patients with Bacterial Pneumonia

Background

Community-acquired pneumonia (CAP) is a global health concern due to its high rates of morbidity and mortality. Bacterial pathogens are common causes of CAP. It is one of the most common causes of acute respiratory distress syndrome (ARDS), a common severe respiratory system manifestation threatening human health. This study aimed to establish a predictive model for ARDS in patients with bacterial pneumonia, which was conducive to early identification of the occurrence and effective prevention of ARDS.

Methods

We collected the clinical data of hospitalized patients with bacterial pneumonia in Affiliated Huzhou Hospital of Zhejiang University School of Medicine from January 2022 to November 2022. The independent risk factors for ARDS in patients with bacterial pneumonia were determined by univariate and multivariate binary logistic regression analyses. The nomogram was constructed to display the predictive model, and the receiver-operating characteristic curve was plotted to evaluate the predictive value of ARDS.

Results

This study included 254 patients with bacterial pneumonia, of which 114 developed ARDS. The multivariate logistic regression analysis revealed age [odds ratio (OR) = 1.041, P = 0.003], heart rate (OR = 1.020, P = 0.028), lymphocyte count (OR = 0.555, P = 0.033), white blood cell count (OR = 1.062, P = 0.033), bilateral lung lesions (OR = 7.352, P = 0.011) and pleural effusion (OR = 2.512, P = 0.002) as the independent risk factors for ARDS. The predictive model was constructed based on the six independent factors, which was valuable in predicting ARDS with area under the curve of 0.794.

Conclusion

The predictive model was beneficial to evaluate the disease progression in patients with bacterial pneumonia and identify ARDS. Further, our nomogram might help doctors predict the incidence of ARDS and conduct treatment as early as possible.

Driving pressure in mechanical ventilation: A review

Driving pressure (∆P) is a core therapeutic component of mechanical ventilation (MV). Varying levels of ∆P have been employed during MV depending on the type of underlying pathology and severity of injury. However, ∆P levels have also been shown to closely impact hard endpoints such as mortality. Considering this, conducting an in-depth review of ∆P as a unique, outcome-impacting therapeutic modality is extremely important. There is a need to understand the subtleties involved in making sure ∆P levels are optimized to enhance outcomes and minimize harm. We performed this narrative review to further explore the various uses of ∆P, the different parameters that can affect its use, and how outcomes vary in different patient populations at different pressure levels. To better utilize ∆P in MV-requiring patients, additional large-scale clinical studies are needed.

Lower body mass index is an independent predictor of mortality in older patients with acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is associated with high mortality. The impacts of body mass index (BMI) on the morality of older patients with ARDS remain unclear.

Methods

This is a single-center cohort study which was conducted at Taichung Veterans General Hospital, Taiwan. Adult patients admitted to the ICU needing mechanical ventilation with ARDS were included for analysis. We compared the data of older patients (age ≥65 years) with those of younger patients (Age <65 years). The factors associated with in-hospital mortality of older patients were investigated.

Results

This study included a total of 728 (mean age: 66 years; men: 63%) patients, and 425 (58.4%) of them aged ≥65 years. Older patients exhibited lower body mass index (BMI) (23.8 vs 25.2), higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores (28.9 vs 26.3), higher Charlson Comorbidity Index (CCI) (4.0 vs 3.4), and lower Sequential Organ Failure Assessment (SOFA) scores (10.0 vs 11.1) than younger patients. Furthermore, older patients had mortality rates similar to younger patients (40.5% vs 42.9%, P = 0.542), but had longer length of stay in the ICU (17.6 vs 15.6 days, P = 0.047). For older patients, BMI <18.5 (odds ratio [OR], 2.78; 95% confidence interval [CI], 1.45-5.34), high SOFA score (OR, 1.20; 95% CI, 1.12-1.28), and moderate (OR, 1.95; 95% CI 1.20-3.14) or severe ARDS (OR, 2.30; 95% CI 1.26-4.22) were independent risk factors for mortality.

Conclusions

In this cohort, critical ill older patients with ARDS had lower BMI, more comorbidities, and higher APACHE II scores than younger patients. Mortality rate was similar between older and younger patients. Low BMI, high SOFA score, and moderate or severe ARDS were independently associated with mortality in older patients with ARDS.

Advances and Applications of Lung Organoids in the Research on Acute Respiratory Distress Syndrome (ARDS)

Acute Respiratory Distress Syndrome (ARDS) is a sudden onset of lung injury characterized by bilateral pulmonary edema, diffuse inflammation, hypoxemia, and a low P/F ratio. Epithelial injury and endothelial injury are notable in the development of ARDS, which is more severe under mechanical stress. This review explains the role of alveolar epithelial cells and endothelial cells under physiological and pathological conditions during the progression of ARDS. Mechanical injury not only causes ARDS but is also a side effect of ventilator-supporting treatment, which is difficult to model both in vitro and in vivo. The development of lung organoids has seen rapid progress in recent years, with numerous promising achievements made. Multiple types of cells and construction strategies are emerging in the lung organoid culture system. Additionally, the lung-on-a-chip system presents a new idea for simulating lung diseases. This review summarizes the basic features and critical problems in the research on ARDS, as well as the progress in lung organoids, particularly in the rapidly developing microfluidic system-based organoids. Overall, this review provides valuable insights into the three major factors that promote the progression of ARDS and how advances in lung organoid technology can be used to further understand ARDS.

Translational medicine for acute lung injury

Acute lung injury (ALI) is a complex disease with numerous causes. This review begins with a discussion of disease development from direct or indirect pulmonary insults, as well as varied pathogenesis. The heterogeneous nature of ALI is then elaborated upon, including its epidemiology, clinical manifestations, potential biomarkers, and genetic contributions. Although no medication is currently approved for this devastating illness, supportive care and pharmacological intervention for ALI treatment are summarized, followed by an assessment of the pathophysiological gap between human ALI and animal models. Lastly, current research progress on advanced nanomedicines for ALI therapeutics in preclinical and clinical settings is reviewed, demonstrating new opportunities towards developing an effective treatment for ALI.

Convalescent Plasma for Covid-19-Induced ARDS in Mechanically Ventilated Patients

BACKGROUND

Passive immunization with plasma collected from convalescent patients has been regularly used to treat coronavirus disease 2019 (Covid-19). Minimal data are available regarding the use of convalescent plasma in patients with Covid-19-induced acute respiratory distress syndrome (ARDS).

METHODS

In this open-label trial, we randomly assigned adult patients with Covid-19-induced ARDS who had been receiving invasive mechanical ventilation for less than 5 days in a 1:1 ratio to receive either convalescent plasma with a neutralizing antibody titer of at least 1:320 or standard care alone. Randomization was stratified according to the time from tracheal intubation to inclusion. The primary outcome was death by day 28.

RESULTS

A total of 475 patients underwent randomization from September 2020 through March 2022. Overall, 237 patients were assigned to receive convalescent plasma and 238 to receive standard care. Owing to a shortage of convalescent plasma, a neutralizing antibody titer of 1:160 was administered to 17.7% of the patients in the convalescent-plasma group. Glucocorticoids were administered to 466 patients (98.1%). At day 28, mortality was 35.4% in the convalescent-plasma group and 45.0% in the standard-care group (P = 0.03). In a prespecified analysis, this effect was observed mainly in patients who underwent randomization 48 hours or less after the initiation of invasive mechanical ventilation. Serious adverse events did not differ substantially between the two groups.

CONCLUSIONS

The administration of plasma collected from convalescent donors with a neutralizing antibody titer of at least 1:160 to patients with Covid-19-induced ARDS within 5 days after the initiation of invasive mechanical ventilation significantly reduced mortality at day 28. This effect was mainly observed in patients who underwent randomization 48 hours or less after ventilation initiation. (Funded by the Belgian Health Care Knowledge Center; ClinicalTrials.gov number, NCT04558476.).

Synergistic Effects of Resistive Breathing on Endotoxin-Induced Lung Injury in Mice

Introduction

Resistive breathing (RB) is characterized by forceful contractions of the inspiratory muscles, mainly the diaphragm, resulting in large negative intrathoracic pressure and mechanical stress imposed on the lung. We have shown that RB induces lung injury in healthy animals. Whether RB exerts additional injurious effects when added to pulmonary or extrapulmonary lung injury is unknown. Our aim was to study the synergistic effect of RB on lipopolysaccharide (LPS)-induced lung injury.

Methods

C57BL/6 mice inhaled an LPS aerosol (10mg/3mL) or received an intraperitoneal injection of LPS (10 mg/kg). Mice were then anaesthetized, the trachea was surgically exposed, and a nylon band of a specified length was sutured around the trachea, to provoke a reduction of the surface area at 50%. RB through tracheal banding was applied for 24 hours. Respiratory system mechanics were measured, BAL was performed, and lung sections were evaluated for histological features of lung injury.

Results

LPS inhalation increased BAL cellularity, mainly neutrophils (p < 0.001 to ctr), total protein and IL-6 in BAL (p < 0.001 and p < 0.001, respectively) and increased the lung injury score (p = 0.001). Lung mechanics were not altered. Adding RB to inhaled LPS further increased BAL cellularity (p < 0.001 to LPS inh.), total protein (p = 0.016), lung injury score (p = 0.001) and increased TNFa levels in BAL (p = 0.011). Intraperitoneal LPS increased BAL cellularity, mainly macrophages (p < 0.001 to ctr.), total protein levels (p = 0.017), decreased static compliance (p = 0.004) and increased lung injury score (p < 0.001). Adding RB further increased histological features of lung injury (p = 0.022 to LPS ip).

Conclusion

Resistive breathing exerts synergistic injurious effects when combined with inhalational LPS-induced lung injury, while the additive effect on extrapulmonary lung injury is less prominent.

The potential mechanism of Choulingdan mixture in improving acute lung injury based on HPLC-Q-TOF-MS, network pharmacology and in vivo experiments

Choulingdan mixture (CLDM) is an empirical clinical prescription for the adjuvant treatment of acute lung injury (ALI). CLDM has been used for almost 30 years in the clinic. However, its mechanism for improving ALI still needs to be investigated. In this study, high-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (HPLC-Q-TOF-MS/MS) was applied to characterize the overall chemical composition of CLDM. A total of 93 ingredients were characterized, including 25 flavonoids, 20 organic acids, 11 saponins, nine terpenoids, seven tannins and 21 other compounds. Then network pharmacology was applied to predict the potential bioactive components, target genes and signaling pathways of CLDM in improving ALI. Additionally, molecular docking was performed to demonstrate the interaction between the active ingredients and the disease targets. Finally, animal experiments further confirmed that CLDM significantly inhibits pulmonary inflammation, pulmonary edema and oxidative stress in lipopolysaccharide-induced ALI mice by inhibiting the PI3K-AKT signaling pathway. This study enhanced the amount and accuracy of compounds of CLDM and provided new insights into CLDM preventing and treating ALI.

Corticosteroids treatment for pediatric acute respiratory syndrome: A critical review

Approximately 25% of all pediatric consultations are due to respiratory conditions, 10% of which are for asthma. Regarding prevalence, bronchiolitis, acute bronchitis, and respiratory infections are other leading pediatric respiratory illnesses. Compared to the aforementioned diseases, pediatric acute respiratory distress syndrome (PARDS) is rare but lethal in the Intensive Care Unit patients. According to global studies, the mortality in PARDS ranges from 13.3% to 60.7%. Before the Pediatric Acute Lung Injury Consensus Conference (PALICC), adult acute respiratory distress syndrome (ARDS) management guidelines were used for PARDS. The PALICC set new criteria to identify PARDS with a different treatment and management approach. Steroids have been used to treat ARDS in some cases, although their effectiveness in treating pediatric patients is highly debated in the scientific community. This review examines steroid use in treating PARDS, emphasizes current developments in the field, and gives a broad overview of PARDS management.

Early and Dose-Dependent Xenogeneic Mesenchymal Stem Cell Therapy Improved Outcomes in Acute Respiratory Distress Syndrome Rodent Through Ameliorating Inflammation, Oxidative Stress, and Immune Reaction

This study tested whether human umbilical cord-derived mesenchymal stem cells (HUCDMSCs) treatment effectively protected the rat lung against acute respiratory distress syndrome (ARDS) injury, and benefits of early and dose-dependent treatment. Rat pulmonary epithelial cell line L2 (PECL2) were categorized into G1 (PECL2), G2 (PECL2 + healthy rat lung-derived extraction/50 mg/ml co-cultured for 24 h), G3 (PECL2 + ARDS rat lung-derived extraction/50 mg/ml co-cultured for 24 h), and G4 (condition as G3 + HUCDMSCs/1 × 105/co-cultured for 24 h). The result showed that the protein expressions of inflammatory (HMGB-1/TLR-2/TLR-4/MAL/TRAM/MyD88/TRIF/TRAF6/IkB/NF-κB/IL-1β/TNF-α), oxidative-stress/mitochondrial-damaged (NOX-1/NOX-2/ASK1/p-MKK4/p-MKK7/JNKs/JUN/cytosolic-cytochrome-C/cyclophilin-D/DRP1), and cell-apoptotic/fibrotic (cleaved-caspase 3/cleaved-PARP/TGF-β/p-Smad3) biomarkers were significantly increased in G3 than in G1/G2 and were significantly reversed in G4 (all P < 0.001), but they were similar between G1/G2. Adult male rats (n = 42) were equally categorized into group 1 (normal control), group 2 (ARDS only), group 3 [ARDS + HUCDMSCs/1.2 × 106 cells intravenous administration at 3 h after 48 h ARDS induction (i.e., early treatment)], group 4 [ARDS + HUCDMSCs/1.2 × 106 cells intravenous administration at 24 h after 48 h ARDS induction (late treatment)], and group 5 [ARDS + HUCDMSCs/1.2 × 106 cells intravenous administration at 3 h/24 h after-48 h ARDS induction (dose-dependent treatment)]. By day 5 after ARDS induction, the SaO2%/immune regulatory T cells were highest in group 1, lowest in group 2, significantly lower in group 4 than in groups 3/5, and significantly lower in group 3 than in group 5, whereas the circulatory/bronchioalveolar lavage fluid inflammatory cells (CD11b-c+/LyG6+/MPO+)/circulatory immune cells (CD3-C4+/CD3-CD8+)/lung-leakage-albumin level/lung injury score/lung protein expressions of inflammatory (HMGB-1/TLR-2/TLR-4/MAL/TRAM/MyD88/TRIF/TRAF6/IκB-β/p-NF-κB/IL-1β/TNF-α)/fibrotic (p-SMad3/TGF-β), apoptosis (mitochondrial-Bax/cleaved-caspase-3)/oxidative-cell-stress (NOX-1/NOX-2/ASK1/p-MKK4/p-MKK7/p-JNKs/p-cJUN)/mitochondrial damaged (cyclophilin-D/DRP1/cytosolic-cytochrome-C) biomarkers displayed an opposite pattern of SaO2% among the groups (all P < 0.0001). Early administration was superior to and two-dose counterpart was even more superior to late HUCDMSCs treatment for protecting the lung against ARDS injury.

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.

Comparison of Clinical Characteristics and Predictors of Mortality between Direct and Indirect ARDS

Background and Objectives: Acute Respiratory Distress Syndrome (ARDS) is a heterogeneous syndrome that encompasses lung injury from a direct pulmonary or indirect systemic insult. Studies have shown that direct and indirect ARDS differ in their pathophysiologic process. In this study, we aimed to compare the different clinical characteristics and predictors of 28-day mortality between direct and indirect ARDS. Materials and Methods: The data of 1291 ARDS patients from September 2012 to December 2021 at the Second Affiliated Hospital of Chongqing Medical University were reviewed. We enrolled 451 ARDS patients in our study through inclusion and exclusion criteria. According to the risk factors, each patient was divided into direct (n = 239) or indirect (n = 212) ARDS groups. The primary outcome was 28-day mortality. Results: The patients with direct ARDS were more likely to be older (p < 0.001) and male (p = 0.009) and have more comorbidity (p < 0.05) and higher 28-day mortality (p < 0.001) than those with indirect ARDS. Age and multiple organ dysfunction syndrome (MODS) were predictors of 28-day mortality in the direct ARDS group, while age, MODS, creatinine, prothrombin time (PT), and oxygenation index (OI) were independent predictors of 28-day mortality in the indirect ARDS group. Creatinine, PT, and OI have interactions with ARDS types (all p < 0.01). Conclusions: The patients with direct ARDS were more likely to be older and male and have worse conditions and prognoses than those with indirect ARDS. Creatinine, PT, and OI were predictors of 28-day mortality only in the indirect ARDS group. The differences between direct and indirect ARDS suggest the need for different management strategies of ARDS.

Identification of early biomarkers of transcriptomics in alveolar macrophage for the prognosis of intubated ARDS patients

Background

Currently, the rate of morbidity and mortality in acute respiratory distress syndrome (ARDS) remains high. One of the potential reasons for the poor and ineffective therapies is the lack of early and credible indicator of risk prediction that would help specific treatment of severely affected ARDS patients. Nevertheless, assessment of the clinical outcomes with transcriptomics of ARDS by alveolar macrophage has not been performed.

Methods

The expression data GSE116560 was obtained from the Gene Expression Omnibus databases (GEO) in NCBI. This dataset consists of 68 BAL samples from 35 subjects that were collected within 48 h of ARDS. Differentially expressed genes (DEGs) of different outcomes were analyzed using R software. The top 10 DEGs that were up- or down-regulated were analyzed using receiver operating characteristic (ROC) analysis. Kaplan–Meier survival analysis within two categories according to cut-off and the value of prediction of the clinical outcomes via DEGs was verified. GO enrichment, KEGG pathway analysis, and protein–protein interaction were also used for functional annotation of key genes.

Results

24,526 genes were obtained, including 235 up-regulated and 292 down-regulated DEGs. The gene ADORA3 was chosen as the most obvious value to predict the outcome according to the ROC and survival analysis. For functional annotation, ADORA3 was significantly augmented in sphingolipid signaling pathway, cGMP-PKG signaling pathway, and neuroactive ligand-receptor interaction. Four genes (ADORA3, GNB1, NTS, and RHO), with 4 nodes and 6 edges, had the highest score in these clusters in the protein–protein interaction network.

Conclusions

Our results show that the prognostic prediction of early biomarkers of transcriptomics as identified in alveolar macrophage in ARDS can be extended for mechanically ventilated critically ill patients. In the long term, generalizing the concept of biomarkers of transcriptomics in alveolar macrophage could add to improving precision-based strategies in the ICU patients and may also lead to identifying improved strategy for critically ill patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02130-8.

A single-center PICU present status survey of pediatric sepsis-related acute respiratory distress syndrome

BACKGROUND

To describe the incidence, clinical features, outcomes, and mortality risk factors of sepsis associated with acute respiratory distress syndrome (ARDS) in pediatric patients.

METHODS

Patients were included in the study if they met the 2005 version of the International Pediatric Sepsis Consensus Conference and met the Pediatric Acute Lung Injury Consensus Conference (PALICC) definition within 48 h of sepsis diagnosis. Patients were classified as mild, moderate, and severe by the worst oxygenation index (OI) within 72 h of sepsis-related ARDS diagnosis.

RESULTS

Between January 1, 2015 and March 13, 2020, 9836 patients were admitted to the pediatric intensive care unit (PICU) of the Children's Hospital of Chongqing Medical University and 828 (8.4%) were identified with sepsis and 203 (24.5%) met the PALICC definition with a PICU mortality rate of 24.6% (50/203) and a 90-day mortality rate of 40.9% (83/203). After adjusting for septic shock, the pediatric logistic organ dysfunction 2 (PELOD-2), high-frequency oscillation ventilation (HFOV), and continuous renal replacement therapy (CRRT), the variables that retained an independent association with increased 90-day mortality in pediatric sepsis-related ARDS included ARDS severity, the pediatric risk of mortality III (PRISM III), number of organ dysfunctions and use of vasoactive drug types during PICU stay.

CONCLUSIONS

PICU mortality in pediatric sepsis-related ARDS was high (24.6%) and severity of hypoxemia based on the worst OI value 72 h after meeting the PALICC definition accurately stratified the patient outcomes. ARDS severity, PRISM III score, comorbid multiorgan dysfunction, and use of multiple vasoactive drugs during PICU stay were independent risk factors for 90-day mortality in pediatric sepsis-related ARDS.

Intensive care unit resources and patient-centred outcomes in severe COVID-19: a prospective single-centre economic evaluation

During the COVID-19 pandemic, ICU bed shortages sparked a discussion about resource allocation. We aimed to analyse the value of ICU treatment of COVID-19 from a patient-centred health economic perspective. We prospectively included 49 patients with severe COVID-19 and calculated direct medical treatment costs. Quality of life was converted into aggregated quality-adjusted life years using the statistical remaining life expectancy. Costs for non-treatment as the comparator were estimated using the value of statistical life year approach. We used multivariable linear or logistic regression to identify predictors of treatment costs, quality of life and survival. Mean (SD) direct medical treatment costs were higher in patients in ICU with COVID-19 compared with those without (£60,866 (£42,533) vs. £8282 (£14,870), respectively; p < 0.001). This was not solely attributable to prolonged ICU length of stay, as costs per day were also higher (£3115 (£1374) vs. £1490 (£713), respectively; p < 0.001), independent of overall disease severity. We observed a beneficial cost-utility value of £7511 per quality-adjusted life-year gained, even with a more pessimistic assumption towards the remaining life expectancy. Extracorporeal membrane oxygenation therapy provided no additional quality-adjusted life-year benefit. Compared with non-treatment (costs per lost life year, £106,085), ICU treatment (costs per quality-adjusted life-year, £7511) was economically preferable, even with a pessimistic interpretation of patient preferences for survival (sensitivity analysis of the value of statistical life year, £48,848). Length of ICU stay was a positive and extracorporeal membrane oxygenation a negative predictor for quality of life, whereas costs per day were a positive predictor for mortality. These data suggest that despite high costs, ICU treatment for severe COVID-19 may be cost-effective for quality-adjusted life-years gained.

Low-dose intravenous plus inhaled versus intravenous polymyxin B for the treatment of extensive drug-resistant Gram-negative ventilator-associated pneumonia in the critical illnesses: a multi-center matched case-control study

Background

The mortality of extensively drug-resistant Gram-negative (XDR GN) bacilli-induced ventilator-associated pneumonia (VAP) is extremely high. The purpose of this study was to compare the efficacy and safety of inhaled (IH) plus intravenous (IV) polymyxin B versus IV polymyxin B in XDR GN bacilli VAP patients.

Methods

A retrospective multi-center observational cohort study was performed at eight ICUs between January 1^st 2018, and January 1^st 2020 in China. Data from all patients treated with polymyxin B for a microbiologically confirmed VAP were analyzed. The primary endpoint was the clinical cure of VAP. The favorable clinical outcome, microbiological outcome, VAP-related mortality and all-cause mortality during hospitalization, and side effects related with polymyxin B were secondary endpoints. Favorable clinical outcome included clinical cure or clinical improvement.

Results

151 patients and 46 patients were treated with IV polymyxin B and IH plus IV polymyxin B, respectively. XDR Klebsiella pneumoniae was the main isolated pathogen (n = 83, 42.1%). After matching on age (± 5 years), gender, septic shock, and Apache II score (± 4 points) when polymyxin B was started, 132 patients were included. 44 patients received simultaneous IH plus IV polymyxin B and 88 patients received IV polymyxin B. The rates of clinical cure (43.2% vs 27.3%, p = 0.066), bacterial eradication (36.4% vs 23.9%, p = 0.132) as well as VAP-related mortality (27.3% vs 34.1%, p = 0.428), all-cause mortality (34.1% vs 42.0%, p = 0.378) did not show any significant difference between the two groups. However, IH plus IV polymyxin B therapy was associated with improved favorable clinical outcome (77.3% vs 58.0%, p = 0.029). Patients in the different subgroups (admitted with medical etiology, infected with XDR K. pneumoniae, without bacteremia, with immunosuppressive status) were with odd ratios (ORs) in favor of the combined therapy. No patient required polymyxin B discontinuation due to adverse events. Additional use of IH polymyxin B (aOR 2.63, 95% CI 1.06, 6.66, p = 0.037) was an independent factor associated with favorable clinical outcome.

Conclusions

The addition of low-dose IH polymyxin B to low-dose IV polymyxin B did not provide efficient clinical cure and bacterial eradication in VAP caused by XDR GN bacilli.

Keypoints

Additional use of IH polymyxin B was the sole independent risk factor of favorable clinical outcome. Patients in the different subgroups were with HRs substantially favoring additional use of IH polymyxin B. No patients required polymyxin B discontinuation due to adverse events.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01033-5.

Treatment for acute respiratory distress syndrome in adults: A narrative review of phase 2 and 3 trials

INTRODUCTION

Ventilatory management and general supportive care of acute respiratory distress syndrome (ARDS) in the adult population have led to significant clinical improvements, but morbidity and mortality remain high. Pharmacologic strategies acting on the coagulation cascade, inflammation, oxidative stress, and endothelial cell injury have been targeted in the last decade for patients with ARDS, but only a few of these have shown potential benefits with a meaningful clinical response and improved patient outcomes. The lack of availability of specific pharmacologic treatments for ARDS can be attributed to its complex pathophysiology, different risk factors, huge heterogeneity, and difficult classification into specific biological phenotypes and genotypes.

AREAS COVERED

In this narrative review, we briefly discuss the relevance and current advances in pharmacologic treatments for ARDS in adults and the need for the development of new pharmacological strategies.

EXPERT OPINION

Identification of ARDS phenotypes, risk factors, heterogeneity, and pathophysiology may help to design clinical trials personalized according to ARDS-specific features, thus hopefully decreasing the rate of failed clinical pharmacologic trials. This concept is still under clinical investigation and needs further development.

Development and validation of a clinical risk model to predict the hospital mortality in ventilated patients with acute respiratory distress syndrome: a population-based study

Background

Large variability in mortality exists in patients of acute respiratory distress syndrome (ARDS), especially those with invasive ventilation. The aim of this study was to develop a model to predict risk of in-hospital death in ventilated ARDS patients.

Methods

Ventilated patients with ARDS from two public databases (MIMIC-III and eICU-CRD) were randomly divided as training cohort and internal validation cohort. Least absolute shrinkage and selection operator (LASSO) and then Logistic regression was used to construct a predictive model with demographic, clinical, laboratory, comorbidities and ventilation variables ascertained at first 24 h of ICU admission and invasive ventilation. Our model was externally validated using data from another database (MIMIC-IV).

Results

A total of 1075 adult patients from MIMIC-III and eICU were randomly divided into training cohort (70%, n = 752) and internal validation cohort (30%, n = 323). 521 patients were included from MIMIC-IV. From 176 potential predictors, 9 independent predictive factors were included in the final model. Five variables were ascertained within the first 24 h of ICU admission, including age (OR, 1.02; 95% CI: 1.01–1.03), mean of respiratory rate (OR, 1.04; 95% CI: 1.01–1.08), the maximum of INR (OR, 1.14; 95% CI: 1.03–1.31) and alveolo-arterial oxygen difference (OR, 1.002; 95% CI: 1.001–1.003) and the minimum of RDW (OR, 1.17; 95% CI: 1.09–1.27). And four variables were collected within the first 24 h of invasive ventilation: mean of temperature (OR, 0.70; 95% CI: 0.57–0.86), the maximum of lactate (OR, 1.15; 95% CI: 1.09–1.22), the minimum of blood urea nitrogen (OR, 1.02; 95% CI: 1.01–1.03) and white blood cell counts (OR, 1.03; 95% CI: 1.01–1.06). Our model achieved good discrimination (AUC: 0.77, 95% CI: 0.73–0.80) in training cohort but the performance declined in internal (AUC: 0.75, 95% CI: 0.69–0.80) and external validation cohort (0.70, 95% CI: 0.65–0.74) and showed modest calibration.

Conclusions

A risk score based on routinely collected variables at the start of admission to ICU and invasive ventilation can predict mortality of ventilated ARDS patients, with a moderate performance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02057-0.

Epidemiology of Neonatal Acute Respiratory Distress Syndrome: Prospective, Multicenter, International Cohort Study

OBJECTIVES

Age-specific definitions for acute respiratory distress syndrome (ARDS) are available, including a specific definition for neonates (the "Montreux definition"). The epidemiology of neonatal ARDS is unknown. The objective of this study was to describe the epidemiology, clinical course, treatment, and outcomes of neonatal ARDS.

DESIGN

Prospective, international, observational, cohort study.

SETTING

Fifteen academic neonatal ICUs.

PATIENTS

Consecutive sample of neonates of any gestational age admitted to participating sites who met the neonatal ARDS Montreux definition criteria.

MEASUREMENTS AND MAIN RESULTS

Neonatal ARDS was classified as direct or indirect, infectious or noninfectious, and perinatal (≤ 72 hr after birth) or late in onset. Primary outcomes were: 1) survival at 30 days from diagnosis, 2) inhospital survival, and 3) extracorporeal membrane oxygenation (ECMO)-free survival at 30 days from diagnosis. Secondary outcomes included respiratory complications and common neonatal extrapulmonary morbidities. A total of 239 neonates met criteria for the diagnosis of neonatal ARDS. The median prevalence was 1.5% of neonatal ICU admissions with male/female ratio of 1.5. Respiratory treatments were similar across gestational ages. Direct neonatal ARDS (51.5% of neonates) was more common in term neonates and the perinatal period. Indirect neonatal ARDS was often triggered by an infection and was more common in preterm neonates. Thirty-day, inhospital, and 30-day ECMO-free survival were 83.3%, 76.2%, and 79.5%, respectively. Direct neonatal ARDS was associated with better survival outcomes than indirect neonatal ARDS. Direct and noninfectious neonatal ARDS were associated with the poorest respiratory outcomes at 36 and 40 weeks' postmenstrual age. Gestational age was not associated with any primary outcome on multivariate analyses.

CONCLUSIONS

Prevalence and survival of neonatal ARDS are similar to those of pediatric ARDS. The neonatal ARDS subtypes used in the current definition may be associated with distinct clinical outcomes and a different distribution for term and preterm neonates.

Risk factors for acute respiratory distress syndrome in sepsis patients: a retrospective study from a tertiary hospital in China

Background

Less is known about the risk factors for acute respiratory distress syndrome (ARDS) in sepsis patients diagnosed according to sepsis 3.0 criteria. Moreover, the risk factors for ARDS severity remain unclear.

Methods

We retrospectively collected the characteristics of sepsis patients from the intensive care unit of the First Affiliated Hospital of China Medical University from January 2017 to September 2018. Logistic regression was used in determining the risk factors.

Results

529 patients with sepsis were enrolled and 179 developed ARDS. The most common infection sites were acute abdominal infection (n = 304) and pneumonia (n = 117). Multivariate analysis showed that patients with pancreatitis with local infection (odds ratio [OR], 3.601; 95% confidence interval [CI], 1.429–9.073, P = 0.007), pneumonia (OR 3.486; 95% CI 1.890–6.430, P < 0.001), septic shock (OR 2.163; 95% CI 1.429–3.275, P < 0.001), a higher sequential organ failure assessment (SOFA) score (OR 1.241; 95% CI 1.155–1.333, P < 0.001) and non-pulmonary SOFA score (OR 2.849; 95% CI 2.113–3.841, P < 0.001) were independent risk factors for ARDS. Moreover, pneumonia is associated with increased severity of ARDS (OR 2.512; 95% CI 1.039–6.067, P = 0.041).

Conclusions

We determined five risk factors for ARDS in sepsis patients. Moreover, pneumonia is significantly associated with an increased severity of ARDS.

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.

An online nomogram of acute respiratory distress syndrome originating from pulmonary disease

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a highly heterogeneous disease accompanied by high mortality. Our goal was to investigate the risk factors for 28-day mortality and then establish a predictive online nomogram for ARDS originating from pulmonary disease (ARDSp).

METHODS

We examined 1087 patients diagnosed with ARDS from January 2010 to December 2019 at the Second Affiliated Hospital of Chongqing Medical University. A total of 185 ARDSp patients were finally enrolled in the training cohort. A total of 43 ARDSp patients from January 2020 to August 2021 in the Second Affiliated Hospital of Chongqing Medical University and the Traditional Chinese Medical Hospital of Jiangbei District were included in the external validation cohort. Fundamental, clinical and laboratory variables at admission were gathered from medical records, and the 28-day prognosis was followed up.

RESULTS

In the training cohort, it was found that age, sex, C-reactive protein, albumin and multiple organ dysfunction syndrome (MODS) were independent risk factors for 28-day mortality via multivariate logistic regression. The online nomogram software for 28-day mortality showed good discrimination, calibration and clinical utility in both the training cohort and external validation cohort.

CONCLUSIONS

For ARDSp patients, older males, lower C-reactive protein and albumin levels, and MODS were independent predictors of a poor 28-day prognosis. The online nomogram based on five independent factors could act as a predictive appliance in clinical practice.

Phenotyping in acute respiratory distress syndrome: state of the art and clinical implications

PURPOSE OF REVIEW

Decades of research in acute respiratory distress syndrome (ARDS) have led to few interventions that impact clinical outcomes. The pandemic of patients with ARDS due to the novel SARS-CoV-2 infection has stressed the need for more effective therapies in ARDS. Phenotyping may enable successful trials and precision therapeutics in this patient population.

RECENT FINDINGS

Clinical phenotypes that group patients by shared cause, time-course or radiographic presentation are of prognostic value, but their use is limited by misclassification. Physiological phenotypes, including the P/F ratio, ventilatory ratio and dead space fraction, predict poor outcomes but can rapidly change, making them unstable over time. Biologic phenotypes have prognostic value with composite clinical and biomarker sub-phenotypes additionally impacting treatment response but are yet to be prospectively validated.

SUMMARY

Although much progress has been made in ARDS phenotyping, implementation of precision medicine practices will depend on conducting phenotype-aware trials using rapid point of care assays or machine learning algorithms. Omics studies will enhance our understanding of biologic determinants of clinical outcomes in ARDS sub-phenotypes. Whether biologic ARDS sub-phenotypes are specific to this syndrome or rather more broadly identify endotypes of critical illness remains to be determined.

Artificial intelligence for mechanical ventilation: systematic review of design, reporting standards, and bias

BACKGROUND

Artificial intelligence (AI) has the potential to personalise mechanical ventilation strategies for patients with respiratory failure. However, current methodological deficiencies could limit clinical impact. We identified common limitations and propose potential solutions to facilitate translation of AI to mechanical ventilation of patients.

METHODS

A systematic review was conducted in MEDLINE, Embase, and PubMed Central to February 2021. Studies investigating the application of AI to patients undergoing mechanical ventilation were included. Algorithm design and adherence to reporting standards were assessed with a rubric combining published guidelines, satisfying the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis [TRIPOD] statement. Risk of bias was assessed by using the Prediction model Risk Of Bias ASsessment Tool (PROBAST), and correspondence with authors to assess data and code availability.

RESULTS

Our search identified 1,342 studies, of which 95 were included: 84 had single-centre, retrospective study design, with only one randomised controlled trial. Access to data sets and code was severely limited (unavailable in 85% and 87% of studies, respectively). On request, data and code were made available from 12 and 10 authors, respectively, from a list of 54 studies published in the last 5 yr. Ethnicity was frequently under-reported 18/95 (19%), as was model calibration 17/95 (18%). The risk of bias was high in 89% (85/95) of the studies, especially because of analysis bias.

CONCLUSIONS

Development of algorithms should involve prospective and external validation, with greater code and data availability to improve confidence in and translation of this promising approach.

TRIAL REGISTRATION NUMBER

PROSPERO - CRD42021225918.

Alveolar epithelial glycocalyx degradation mediates surfactant dysfunction and contributes to acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure yet has few pharmacologic therapies, reflecting the mechanistic heterogeneity of lung injury. We hypothesized that damage to the alveolar epithelial glycocalyx, a layer of glycosaminoglycans interposed between the epithelium and surfactant, contributes to lung injury in patients with ARDS. Using mass spectrometry of airspace fluid noninvasively collected from mechanically ventilated patients, we found that airspace glycosaminoglycan shedding (an index of glycocalyx degradation) occurred predominantly in patients with direct lung injury and was associated with duration of mechanical ventilation. Male patients had increased shedding, which correlated with airspace concentrations of matrix metalloproteinases. Selective epithelial glycocalyx degradation in mice was sufficient to induce surfactant dysfunction, a key characteristic of ARDS, leading to microatelectasis and decreased lung compliance. Rapid colorimetric quantification of airspace glycosaminoglycans was feasible and could provide point-of-care prognostic information to clinicians and/or be used for predictive enrichment in clinical trials.

Awake prone positioning in nonintubated spontaneous breathing ICU patients with acute hypoxemic respiratory failure (PRONELIFE)-protocol for a randomized clinical trial

BACKGROUND

It is uncertain whether awake prone positioning can prevent intubation for invasive ventilation in spontaneous breathing critically ill patients with acute hypoxemic respiratory failure. Awake prone positioning could benefit these patients for various reasons, including a reduction in direct harm to lung tissue, and prevention of tracheal intubation-related complications.

DESIGN AND METHODS

The PRONELIFE study is an investigator-initiated, international, multicenter, randomized clinical trial in patients who may need invasive ventilation because of acute hypoxemic respiratory failure. Consecutive patients admitted to participating ICUs are randomly assigned to standard care with awake prone positioning, versus standard care without awake prone positioning. The primary endpoint is a composite of tracheal intubation and all-cause mortality in the first 14 days after enrolment. Secondary endpoints include time to tracheal intubation and effects of awake prone positioning on oxygenation parameters, dyspnea sensation, and complications. Other endpoints are the number of days free from ventilation and alive at 28 days, total duration of use of noninvasive respiratory support, total duration of invasive ventilation, length of stay in ICU and hospital, and mortality in ICU and hospital, and at 28, 60, and 90 days. We will also collect data regarding the tolerance of prone positioning.

DISCUSSION

The PRONELIFE study is among the first randomized clinical trials investigating the effect of awake prone positioning on intubation rate in ICU patients with acute hypoxemic failure from any cause. The PRONELIFE study is sufficiently sized to determine the effect of awake prone positioning on intubation for invasive ventilation-patients are eligible in case of acute hypoxemic respiratory failure without restrictions regarding etiology. The PRONELIFE study is a pragmatic trial in which blinding is impossible-however, as around 35 ICUs worldwide will participate in this study, its findings will be highly generalizable. The findings of the PRONELIFE study have the potential to change clinical management of patients who may need invasive ventilation because of acute hypoxemic respiratory failure.

TRIAL REGISTRATION

ISRCTN ISRCTN11536318 . Registered on 17 September 2021. The PRONELIFE study is registered at clinicaltrials.gov with reference number NCT04142736 (October, 2019).

Advancing precision medicine for acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a heterogeneous clinical syndrome. Understanding of the complex pathways involved in lung injury pathogenesis, resolution, and repair has grown considerably in recent decades. Nevertheless, to date, only therapies targeting ventilation-induced lung injury have consistently proven beneficial, and despite these gains, ARDS morbidity and mortality remain high. Many candidate therapies with promise in preclinical studies have been ineffective in human trials, probably at least in part due to clinical and biological heterogeneity that modifies treatment responsiveness in human ARDS. A precision medicine approach to ARDS seeks to better account for this heterogeneity by matching therapies to subgroups of patients that are anticipated to be most likely to benefit, which initially might be identified in part by assessing for heterogeneity of treatment effect in clinical trials. In October 2019, the US National Heart, Lung, and Blood Institute convened a workshop of multidisciplinary experts to explore research opportunities and challenges for accelerating precision medicine in ARDS. Topics of discussion included the rationale and challenges for a precision medicine approach in ARDS, the roles of preclinical ARDS models in precision medicine, essential features of cohort studies to advance precision medicine, and novel approaches to clinical trials to support development and validation of a precision medicine strategy. In this Position Paper, we summarise workshop discussions, recommendations, and unresolved questions for advancing precision medicine in ARDS. Although the workshop took place before the COVID-19 pandemic began, the pandemic has highlighted the urgent need for precision therapies for ARDS as the global scientific community grapples with many of the key concepts, innovations, and challenges discussed at this workshop.

Personalized medicine using omics approaches in acute respiratory distress syndrome to identify biological phenotypes

In the last decade, research on acute respiratory distress syndrome (ARDS) has made considerable progress. However, ARDS remains a leading cause of mortality in the intensive care unit. ARDS presents distinct subphenotypes with different clinical and biological features. The pathophysiologic mechanisms of ARDS may contribute to the biological variability and partially explain why some pharmacologic therapies for ARDS have failed to improve patient outcomes. Therefore, identifying ARDS variability and heterogeneity might be a key strategy for finding effective treatments. Research involving studies on biomarkers and genomic, metabolomic, and proteomic technologies is increasing. These new approaches, which are dedicated to the identification and quantitative analysis of components from biological matrixes, may help differentiate between different types of damage and predict clinical outcome and risk. Omics technologies offer a new opportunity for the development of diagnostic tools and personalized therapy in ARDS. This narrative review assesses recent evidence regarding genomics, proteomics, and metabolomics in ARDS research.

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.

The Association Between Etiologies and Mortality in Acute Respiratory Distress Syndrome: A Multicenter Observational Cohort Study

Background: Lung-protective ventilation (LPV) strategies have been beneficial in patients with acute respiratory distress syndrome (ARDS). As a vital part of LPV, positive end-expiratory pressure (PEEP) can enhance oxygenation. However, randomized clinical trials of different PEEP strategies seem to show no advantages in clinical outcomes in patients with ARDS. A potential reason is that diverse etiologies and phenotypes in patients with ARDS may account for different PEEP responses, resulting in variations in mortality. We consider hospital mortality to be associated with a more specific classification of ARDS, such as sepsis induced or not, and pulmonary or extrapulmonary one. Our study aimed to compare clinical outcomes in various patients with ARDS by etiologies using the China Critical Care Sepsis Trial (CCCST) database. This was a retrospective analysis of a prospective cohort of 2,138 patients with ARDS in the CCCST database. According to ARDS induced by sepsis or not and medical history, patients were stratified into different four groups. Differences among groups were assessed in hospital mortality, ventilation-free days, and other clinical features.

Results: A total of 2,138 patients with ARDS were identified in the database, including 647 patients with sepsis-induced pulmonary ARDS (30.3%), 396 patients with sepsis-induced extrapulmonary ARDS (18.5%), 536 patients with non-sepsis pulmonary ARDS (25.1%), and 559 patients with non-sepsis extrapulmonary ARDS (26.1%). The pulmonary ARDS group had higher mortality compared with the extrapulmonary group (45.9 vs. 23.0%, p < 0.01), longer intensive care unit (ICU) and hospital stays (9 vs. 6 days, p < 0.01, 20 vs. 18 days, p = 0.01, respectively), and fewer ventilation-free days (5 vs. 9 days) in the presence of sepsis. However, the mortality in ARDS without sepsis was inverted compared with extrapulmonary ARDS (pulmonary 23.5% vs. extrapulmonary 29.2%, p = 0.04). After adjusting for the Acute Physiology and Chronic Health Evaluation II and sequential organ failure assessment scores and other clinical features, the sepsis-induced pulmonary condition was still a risk factor for death in patients with ARDS (hazard ratio 0.66, 95% CI, 0.54–0.82, p < 0.01) compared with sepsis-induced extrapulmonary ARDS and other subphenotypes.

Conclusions: In the presence of sepsis, hospital mortality in pulmonary ARDS is higher compared with extrapulmonary ARDS; however, mortality is inverted in ARDS without sepsis. Sepsis-induced pulmonary ARDS should attract more attention from ICU physicians and be cautiously treated.

Trial registration: ChiCTR-ECH-13003934. Registered August 3, 2013, http://www.chictr.org.cn.

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.

Comparisons of Outcomes between Patients with Direct and Indirect Acute Respiratory Distress Syndrome Receiving Extracorporeal Membrane Oxygenation

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome caused by direct (local damage to lung parenchyma) or indirect lung injury (insults from extrapulmonary sites with acute systemic inflammatory response), the clinical and biological complexity can have a profound effect on clinical outcomes. We performed a retrospective analysis of 152 severe ARDS patients receiving extracorporeal membrane oxygenation (ECMO). Our objective was to assess the differences in clinical characteristics and outcomes of direct and indirect ARDS patients receiving ECMO. Overall hospital mortality was 53.3%. A total of 118 patients were assigned to the direct ARDS group, and 34 patients were assigned to the indirect ARDS group. The 28-, 60-, and 90-day hospital mortality rates were significantly higher among indirect ARDS patients (all p < 0.05). Cox regression models demonstrated that among direct ARDS patients, diabetes mellitus, immunocompromised status, ARDS duration before ECMO, and SOFA score during the first 3 days of ECMO were independently associated with mortality. In indirect ARDS patients, SOFA score and dynamic compliance during the first 3 days of ECMO were independently associated with mortality. Our findings revealed that among patients receiving ECMO, direct and indirect subphenotypes of ARDS have distinct clinical outcomes and different predictors for mortality.

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute respiratory illness characterised by bilateral chest radiographical opacities with severe hypoxaemia due to non-cardiogenic pulmonary oedema. The COVID-19 pandemic has caused an increase in ARDS and highlighted challenges associated with this syndrome, including its unacceptably high mortality and the lack of effective pharmacotherapy. In this Seminar, we summarise current knowledge regarding ARDS epidemiology and risk factors, differential diagnosis, and evidence-based clinical management of both mechanical ventilation and supportive care, and discuss areas of controversy and ongoing research. Although the Seminar focuses on ARDS due to any cause, we also consider commonalities and distinctions of COVID-19-associated ARDS compared with ARDS from other causes.

Acute Respiratory Distress Syndrome in the Elderly

Acute respiratory distress syndrome (ARDS) is a commonly encountered complex syndrome of varied etiology and outcomes. The elderly population is at a high risk of developing severe ARDS with poor outcomes. The age-related changes in the immune system, structural and functional modifications of the respiratory system, and the frailty with a decrease in the physiological reserve of organ systems place them precariously for poor outcomes. However, does age alone influence the outcomes or is it the associated comorbidities that determine mortality in the elderly is not clearly known.

HOW TO CITE THIS ARTICLE

Jagathkar G. Acute Respiratory Distress Syndrome in the Elderly. Indian J Crit Care Med 2021;25(6):613-614.

Human Umbilical Cord-Derived Mesenchymal Stem Cells for Acute Respiratory Distress Syndrome

OBJECTIVES

To investigate the safety, feasibility, and possible adverse events of single-dose human umbilical cord-derived mesenchymal stem cells in patients with moderate-to-severe acute respiratory distress syndrome.

DESIGN

Prospective phase I clinical trial.

SETTING

Medical center in Kaohsiung, Taiwan.

PATIENTS

Moderate-to-severe acute respiratory distress syndrome with a PaO2/FIO2 ratio less than 200.

INTERVENTIONS

Scaling for doses was required by Taiwan Food and Drug Administration as follows: the first three patients received low-dose human umbilical cord-derived mesenchymal stem cells (1.0 × 10 cells/kg), the next three patients with intermediate dose (5.0 × 10 cells/kg), and the final three patients with high dose (1.0 × 10 cells/kg) between December 2017 and August 2019.

MEASUREMENTS AND MAIN RESULTS

Nine consecutive patients were enrolled into the study. In-hospital mortality was 33.3% (3/9), including two with recurrent septic shock and one with ventilator-induced severe pneumomediastinum and subcutaneous emphysema. No serious prespecified cell infusion-associated or treatment-related adverse events was identified in any patient. Serial flow-cytometric analyses of circulating inflammatory biomarkers (CD14CD33/CD11b+CD16+/CD16+MPO+/CD11b+MPO+/CD14CD33+) and mesenchymal stem cell markers (CD26+CD45-/CD29+CD45-/CD34+CD45-/CD44+CD45-/CD73+CD45-/CD90+CD45-/CD105+CD45-/CD26+CD45-) were notably progressively reduced (p for trend < 0.001), whereas the immune cell markers (Helper-T-cell/Cytotoxity-T-cell/Regulatory-T-cell) were notably increased (p for trend < 0.001) after cell infusion.

CONCLUSIONS

The result of this phase I clinical trial showed that a single-dose IV infusion of human umbilical cord-derived mesenchymal stem cells was safe with favorable outcome in nine acute respiratory distress syndrome patients.

Mortality prediction for patients with acute respiratory distress syndrome based on machine learning: a population-based study

Background

Traditional scoring systems for patients' outcome prediction in intensive care units such as Oxygenation Saturation Index (OSI) and Oxygenation Index (OI) may not reliably predict the clinical prognosis of patients with acute respiratory distress syndrome (ARDS). Thus, none of them have been widely accepted for mortality prediction in ARDS. This study aimed to develop and validate a mortality prediction method for patients with ARDS based on machine learning using the Medical Information Mart for Intensive Care (MIMIC-III) and Telehealth Intensive Care Unit (eICU) Collaborative Research Database (eICU-CRD) databases.

Methods

Patients with ARDS were selected based on the Berlin definition in MIMIC-III and eICU-CRD databases. The APPS score (using age, PaO₂/FiO₂, and plateau pressure), Simplified Acute Physiology Score II (SAPS-II), Sepsis-related Organ Failure Assessment (SOFA), OSI, and OI were calculated. With MIMIC-III data, a mortality prediction model was built based on the random forest (RF) algorithm, and the performance was compared to those of existing scoring systems based on logistic regression. The performance of the proposed RF method was also validated with the combined MIMIC-III and eICU-CRD data. The performance of mortality prediction was evaluated by using the area under the receiver operating characteristics curve (AUROC) and performing calibration using the Hosmer-Lemeshow test.

Results

With the MIMIC-III dataset (308 patients, for comparisons with the existing scoring systems), the RF model predicted the in-hospital mortality, 30-day mortality, and 1-year mortality with an AUROC of 0.891, 0.883, and 0.892, respectively, which were significantly higher than those of the SAPS-II, APPS, OSI, and OI (all P<0.001). In the multi-source validation (the combined dataset of 2,235 patients in MIMIC-III and 331 patients in eICU-CRD), the RF model achieved an AUROC of 0.905 and 0.736 for predicting in-hospital mortality for the MIMIC-III and eICU-CRD datasets, respectively. The calibration plots suggested good fits for our RF model and these scoring systems for predicting mortality. The platelet count and lactate level were the strongest predictive variables for predicting in-hospital mortality.

Conclusions

Compared to the existing scoring systems, machine learning significantly improved performance for predicting ARDS mortality. Validation with multi-source datasets showed a relatively robust generalisation ability of our prediction model.

Association Between Incident Delirium Treatment With Haloperidol and Mortality in Critically Ill Adults

OBJECTIVES

Haloperidol is commonly administered in the ICU to reduce the burden of delirium and its related symptoms despite no clear evidence showing haloperidol helps to resolve delirium or improve survival. We evaluated the association between haloperidol, when used to treat incident ICU delirium and its symptoms, and mortality.

DESIGN

Post hoc cohort analysis of a randomized, double-blind, placebo-controlled, delirium prevention trial.

SETTING

Fourteen Dutch ICUs between July 2013 and December 2016.

PATIENTS

One-thousand four-hundred ninety-five critically ill adults free from delirium at ICU admission having an expected ICU stay greater than or equal to 2 days.

INTERVENTIONS

Patients received preventive haloperidol or placebo for up to 28 days until delirium occurrence, death, or ICU discharge. If delirium occurred, treatment with open-label IV haloperidol 2 mg tid (up to 5 mg tid per delirium symptoms) was administered at clinician discretion.

MEASUREMENTS AND MAIN RESULTS

Patients were evaluated tid for delirium and coma for 28 days. Time-varying Cox hazards models were constructed for 28-day and 90-day mortality, controlling for study-arm, delirium and coma days, age, Acute Physiology and Chronic Health Evaluation-II score, sepsis, mechanical ventilation, and ICU length of stay. Among the 1,495 patients, 542 (36%) developed delirium within 28 days (median [interquartile range] with delirium 4 d [2-7 d]). A total of 477 of 542 (88%) received treatment haloperidol (2.1 mg [1.0-3.8 mg] daily) for 6 days (3-11 d). Each milligram of treatment haloperidol administered daily was associated with decreased mortality at 28 days (hazard ratio, 0.93; 95% CI, 0.91-0.95) and 90 days (hazard ratio, 0.97; 95% CI, 0.96-0.98). Treatment haloperidol administered later in the ICU course was less protective of death. Results were stable by prevention study-arm, predelirium haloperidol exposure, and haloperidol treatment protocol adherence.

CONCLUSIONS

Treatment of incident delirium and its symptoms with haloperidol may be associated with a dose-dependent improvement in survival. Future randomized trials need to confirm these results.

Inhibition of Caspase-1 with Tetracycline Ameliorates Acute Lung Injury

Rationale: Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome with a mortality of up to 40%. Precision medicine approaches targeting patients on the basis of their molecular phenotypes of ARDS might help to identify effective pharmacotherapies. The inflammasome-caspase-1 pathway contributes to the development of ARDS via IL-1β and IL-18 production. Recent studies indicate that tetracycline can be used to treat inflammatory diseases mediated by IL-1β and IL-18, although the molecular mechanism by which tetracycline inhibits inflammasome-caspase-1 signaling remains unknown. Objectives: To identify patients with ARDS characterized by IL-1β and IL-18 expression and investigate the ability of tetracycline to inhibit inflammasome-caspase-1 signaling in ARDS. Methods: IL-1β and IL-18 concentrations were quantified in BAL fluid from patients with ARDS. Tetracycline's effects on lung injury and inflammation were assessed in two mouse models of direct (pulmonary) acute lung injury, and its effects on IL-1β and IL-18 production were assessed by alveolar leukocytes from patients with direct ARDS ex vivo. Murine macrophages were used to further characterize the effect of tetracycline on the inflammasome-caspase-1 pathway. Measurements and Main Results: BAL fluid concentrations of IL-1β and IL-18 are significantly higher in patients with direct ARDS than those with indirect (nonpulmonary) ARDS. In experimental acute lung injury, tetracycline significantly diminished lung injury and pulmonary inflammation by selectively inhibiting caspase-1-dependent IL-1β and IL-18 production, leading to improved survival. Tetracycline also reduced the production of IL-1β and IL-18 by alveolar leukocytes from patients with direct ARDS. Conclusions: Tetracycline may be effective in the treatment of direct ARDS in patients with elevated caspase-1 activity. Clinical Trial registered with www.clinicaltrials.gov (NCT04079426).

Surfactant therapies for pediatric and neonatal ARDS: ESPNIC expert consensus opinion for future research steps

Pediatric (PARDS) and neonatal (NARDS) acute respiratory distress syndrome have different age-specific characteristics and definitions. Trials on surfactant for ARDS in children and neonates have been performed well before the PARDS and NARDS definitions and yielded conflicting results. This is mainly due to heterogeneity in study design reflecting historic lack of pathobiology knowledge. We reviewed the available clinical and preclinical data to create an expert consensus aiming to inform future research steps and advance the knowledge in this area. Eight trials investigated the use of surfactant for ARDS in children and ten in neonates, respectively. There were improvements in oxygenation (7/8 trials in children, 7/10 in neonates) and mortality (3/8 trials in children, 1/10 in neonates) improved. Trials were heterogeneous for patients' characteristics, surfactant type and administration strategy. Key pathobiological concepts were missed in study design. Consensus with strong agreement was reached on four statements: 1. There are sufficient preclinical and clinical data to support targeted research on surfactant therapies for PARDS and NARDS. Studies should be performed according to the currently available definitions and considering recent pathobiology knowledge. 2. PARDS and NARDS should be considered as syndromes and should be pre-clinically studied according to key characteristics, such as direct or indirect (primary or secondary) nature, clinical severity, infectious or non-infectious origin or patients' age. 3. Explanatory should be preferred over pragmatic design for future trials on PARDS and NARDS. 4. Different clinical outcomes need to be chosen for PARDS and NARDS, according to the trial phase and design, trigger type, severity class and/or surfactant treatment policy. We advocate for further well-designed preclinical and clinical studies to investigate the use of surfactant for PARDS and NARDS following these principles.

The discovery of biological subphenotypes in ARDS: a novel approach to targeted medicine?

The acute respiratory distress syndrome (ARDS) is a severe lung disorder with a high morbidity and mortality which affects all age groups. Despite active research with intense, ongoing attempts in developing pharmacological agents to treat ARDS, its mortality rate remains unaltered high and treatment is still only supportive. Over the years, there have been many attempts to identify meaningful subgroups likely to react differently to treatment among the heterogenous ARDS population, most of them unsuccessful. Only recently, analysis of large ARDS cohorts from randomized controlled trials have identified the presence of distinct biological subphenotypes among ARDS patients: a hypoinflammatory (or uninflamed; named P1) and a hyperinflammatory (or reactive; named P2) subphenotype have been proposed and corroborated with existing retrospective data. The hyperinflammatory subphenotyope was clearly associated with shock state, metabolic acidosis, and worse clinical outcomes. Core features of the respective subphenotypes were identified consistently in all assessed cohorts, independently of the studied population, the geographical location, the study design, or the analysis method. Additionally and clinically even more relevant treatment efficacies, as assessed retrospectively, appeared to be highly dependent on the respective subphenotype. This discovery launches a promising new approach to targeted medicine in ARDS. Even though it is now widely accepted that each ARDS subphenotype has distinct functional, biological, and mechanistic differences, there are crucial gaps in our knowledge, hindering the translation to bedside application. First of all, the underlying driving biological factors are still largely unknown, and secondly, there is currently no option for fast and easy identification of ARDS subphenotypes. This narrative review aims to summarize the evidence in biological subphenotyping in ARDS and tries to point out the current issues that will need addressing before translation of biological subohenotypes into clinical practice will be possible.

Peripheral blood transcriptomic sub-phenotypes of pediatric acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is heterogeneous and may be amenable to sub-phenotyping to improve enrichment for trials. We aimed to identify subtypes of pediatric ARDS based on whole blood transcriptomics.

Methods

This was a prospective observational study of children with ARDS at the Children’s Hospital of Philadelphia (CHOP) between January 2018 and June 2019. We collected blood within 24 h of ARDS onset, generated expression profiles, and performed k-means clustering to identify sub-phenotypes. We tested the association between sub-phenotypes and PICU mortality and ventilator-free days at 28 days using multivariable logistic and competing risk regression, respectively.

Results

We enrolled 106 subjects, of whom 96 had usable samples. We identified three sub-phenotypes, dubbed CHOP ARDS Transcriptomic Subtypes (CATS) 1, 2, and 3. CATS-1 subjects (n = 31) demonstrated persistent hypoxemia, had ten subjects (32%) with immunocompromising conditions, and 32% mortality. CATS-2 subjects (n = 29) had more immunocompromising diagnoses (48%), rapidly resolving hypoxemia, and 24% mortality. CATS-3 subjects (n = 36) had the fewest comorbidities and also had rapidly resolving hypoxemia and 8% mortality. The CATS-3 subtype was associated with lower mortality (OR 0.18, 95% CI 0.04–0.86) and higher probability of extubation (subdistribution HR 2.39, 95% CI 1.32–4.32), relative to CATS-1 after adjustment for confounders.

Conclusions

We identified three sub-phenotypes of pediatric ARDS using whole blood transcriptomics. The sub-phenotypes had divergent clinical characteristics and prognoses. Further studies should validate these findings and investigate mechanisms underlying differences between sub-phenotypes.

Diagnosis and Management of Acute Respiratory Distress Syndrome in a Time of COVID-19

Acute respiratory distress syndrome (ARDS) remains a serious illness with significant morbidity and mortality, characterized by hypoxemic respiratory failure most commonly due to pneumonia, sepsis, and aspiration. Early and accurate diagnosis of ARDS depends upon clinical suspicion and chest imaging. Coronavirus disease 2019 (COVID-19) is an important novel cause of ARDS with a distinct time course, imaging and laboratory features from the time of SARS-CoV-2 infection to hypoxemic respiratory failure, which may allow diagnosis and management prior to or at earlier stages of ARDS. Treatment of ARDS remains largely supportive, and consists of incremental respiratory support (high flow nasal oxygen, non-invasive respiratory support, and invasive mechanical ventilation), and avoidance of iatrogenic complications, all of which improve clinical outcomes. COVID-19-associated ARDS is largely similar to other causes of ARDS with respect to pathology and respiratory physiology, and as such, COVID-19 patients with hypoxemic respiratory failure should typically be managed as other patients with ARDS. Non-invasive respiratory support may be beneficial in avoiding intubation in COVID-19 respiratory failure including mild ARDS, especially under conditions of resource constraints or to avoid overwhelming critical care resources. Compared to other causes of ARDS, medical therapies may improve outcomes in COVID-19-associated ARDS, such as dexamethasone and remdesivir. Future improved clinical outcomes in ARDS of all causes depends upon individual patient physiological and biological endotyping in order to improve accuracy and timeliness of diagnosis as well as optimal targeting of future therapies in the right patient at the right time in their disease.

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.

PAD4 selective inhibitor TDFA protects lipopolysaccharide-induced acute lung injury by modulating nuclear p65 localization in epithelial cells

Protein arginine deiminase 4 (PAD4) serves a critical role in differentiation, development and apoptosis through gene regulation and has emerged as a potential therapeutic target for the treatment of various diseases. However, the roles of PAD4 in lipopolysaccharide (LPS)-induced acute lung injury (ALI) remain largely unknown. To investigate the roles of PAD4 during LPS-induced ALI, the present study detected the trend of PAD4 expression in the lung tissues of ALI mice. Subsequently, the efficiency of TDFA on PAD4 and citrullinated H3 histone were detected. And then, histology, the wet/dry weight ratio, survival rate, activated cells infiltration, oxidative stress levels, tight junction proteins and proinflammatory cytokine expression were detected. In addition, the level of transepithelial electrical resistance (TEER) was assessed. Finally, the level of nuclear P65, total phosphorylated P65 and P65 were measured in vivo and in vitro. The results showed that PAD4 expression was upregulated in the lung tissues of LPS-induced ALI. TDFA efficiently decreased the severity of the lung edema, attenuated the severity of pulmonary injury and improved the survival rate following lethal LPS administration. Besides, TDFA reduced activated cells infiltration and suppressed inflammation related parameters, including proinflammatory cytokines production (TNF-α, IL-6 and IL-1β) and oxidative stress (MDA, GSH and SOD). Furthermore, TDFA reversed the TEER downregulation tendency and tight junction proteins (ZO-1, Occludin, Claudin-4) levels that represent the integrity of alveolar epithelium. Eventually, TDFA exerts its protective roles through modulating nuclear localization of transcription factor NF-κB P65 in epithelial cells. Taken together, these results indicate that PAD4 inhibition may serve as a promising therapeutic approach for LPS-induced ALI.

Soluble PD-L1 improved direct ARDS by reducing monocyte-derived macrophages

Acute respiratory distress syndrome (ARDS) is common in intensive care units (ICUs), although it is associated with high mortality, no effective pharmacological treatments are currently available. Despite being poorly understood, the role of programmed cell death protein 1 (PD-1) and PD-ligand 1 (PD-L1) axis in ARDS may provide significant insights into the immunosuppressive mechanisms that occur after ARDS. In the present study, we observed that the level of soluble PD-L1 (sPD-L1), a potential activator of the PD-1 pathway, was upregulated in survivors of direct ARDS than in non-survivors. Administration of sPD-L1 in mice with direct ARDS relieved inflammatory lung injury and improved the survival rate, indicating the protective role of sPD-L1 in direct ARDS. Using high-throughput mass cytometry, we found a marked decrease in the number of lung monocyte-derived macrophages (MDMs) with proinflammatory markers, and the protective role of sPD-L1 diminished in ARDS mice with monocyte/macrophage depletion. Furthermore, PD-1 expression increased in the MDMs of patients and mice with direct ARDS. Finally, we showed that sPD-L1 induced MDM apoptosis in patients with direct ARDS. Taken together, our results demonstrated that the engagement of sPD-L1 on PD-1 expressing macrophages resulted in a decrease in pro-inflammatory macrophages and eventually improved direct ARDS. Our study identified a prognostic indicator for patients with direct ARDS and a potential target for therapeutic development in direct ARDS.

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.

Factors influencing liberation from mechanical ventilation in coronavirus disease 2019: multicenter observational study in fifteen Italian ICUs

BACKGROUND

A large proportion of patients with coronavirus disease 2019 (COVID-19) develop severe respiratory failure requiring admission to the intensive care unit (ICU) and about 80% of them need mechanical ventilation (MV). These patients show great complexity due to multiple organ involvement and a dynamic evolution over time; moreover, few information is available about the risk factors that may contribute to increase the time course of mechanical ventilation.The primary objective of this study is to investigate the risk factors associated with the inability to liberate COVID-19 patients from mechanical ventilation. Due to the complex evolution of the disease, we analyzed both pulmonary variables and occurrence of non-pulmonary complications during mechanical ventilation. The secondary objective of this study was the evaluation of risk factors for ICU mortality.

METHODS

This multicenter prospective observational study enrolled 391 patients from fifteen COVID-19 dedicated Italian ICUs which underwent invasive mechanical ventilation for COVID-19 pneumonia. Clinical and laboratory data, ventilator parameters, occurrence of organ dysfunction, and outcome were recorded. The primary outcome measure was 28 days ventilator-free days and the liberation from MV at 28 days was studied by performing a competing risks regression model on data, according to the method of Fine and Gray; the event death was considered as a competing risk.

RESULTS

Liberation from mechanical ventilation was achieved in 53.2% of the patients (208/391). Competing risks analysis, considering death as a competing event, demonstrated a decreased sub-hazard ratio for liberation from mechanical ventilation (MV) with increasing age and SOFA score at ICU admission, low values of PaO2/FiO2 ratio during the first 5 days of MV, respiratory system compliance (CRS) lower than 40 mL/cmH2O during the first 5 days of MV, need for renal replacement therapy (RRT), late-onset ventilator-associated pneumonia (VAP), and cardiovascular complications.ICU mortality during the observation period was 36.1% (141/391). Similar results were obtained by the multivariate logistic regression analysis using mortality as a dependent variable.

CONCLUSIONS

Age, SOFA score at ICU admission, CRS, PaO2/FiO2, renal and cardiovascular complications, and late-onset VAP were all independent risk factors for prolonged mechanical ventilation in patients with COVID-19.

TRIAL REGISTRATION

NCT04411459.

Incidence and impact of extra-pulmonary organ failures on hospital mortality in acute exacerbation of idiopathic pulmonary fibrosis

To evaluate hospital mortality and associated risk factors for acute exacerbations of idiopathic pulmonary fibrosis (AEIPF). Emphases were put on incidence and impact of extra-pulmonary organ failures. Patients diagnosed with AEIPF from July 2014 to September 2018 were enrolled. Clinical data were collected. Acute physiology and chronic health evaluation II (APACHE II) and simplified acute physiological score II (SAPS II) were calculated. Extra-pulmonary organ failures were diagnosed upon criteria of sequential organ failure assessment (SOFA). Forty-five patients with AEIPF were included. Eighteen patients (40.0%) developed extra-pulmonary organ failures, and 25 patients (55.6%) died during hospitalization. Serum C-reactive protein (CRP) (p = 0.001), SAPS II (p = 0.004), SOFA (p = 0.001) were higher, whereas arterial oxygen pressure (PaO₂)/ fractional inspired oxygen (FiO₂) (p = 0.001) was lower in non-survivors than survivors. More non-survivors developed extra-pulmonary organ failures than survivors (p = 0.002). After adjustment, elevated serum CRP (OR 1.038, p = 0.049) and extra-pulmonary organ failure (OR 13.126, p = 0.016) were independent predictors of hospital mortality in AEIPF. AEIPF had high hospital mortality and occurrence of extra-pulmonary organ failure was common. Elevated serum CRP and extra-pulmonary organ failure had predictive values for mortality.

Epigallocatechin-3-Gallate (EGCG), an Active Compound of Green Tea Attenuates Acute Lung Injury Regulating Macrophage Polarization and Krüpple-Like-Factor 4 (KLF4) Expression

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are serious clinical complications with a high frequency of morbidity and mortality. The initiation and amplification of inflammation is a well-known aspect in the pathogenesis of ALI and related disorders. Therefore, inhibition of the inflammatory mediators could be an ideal approach to prevent ALI. Epigallocatechin-3-gallate (EGCG), a major constituent of green tea, has been shown to have protective effects on oxidative damage and anti-inflammation. The goal of the present study was to determine whether EGCG improves phenotype and macrophage polarisation in LPS-induced ALI. C57BL/6 mice were given two doses of EGCG (15 mg/kg) intraperitoneally (IP) 1 h before and 3 h after LPS instillation (2 mg/kg). EGCG treatment improved histopathological lesions, Total Leucocyte count (TLC), neutrophils infiltration, wet/dry ratio, total proteins and myeloperoxidase (MPO) activity in LPS-induced lung injury. The results displayed that EGCG reduced LPS-induced ALI as it modulates macrophage polarisation towards M2 status. Furthermore, EGCG also reduced the expression of proinflammatory M1 mediators iNOS TNF-α, IL-1β and IL-6 in the LPS administered lung microenvironment. In addition, it increased the expression of KLF4, Arg1 and ym1, known to augment the M2 phenotype of macrophages. EGCG also alleviated the expression of 8-OHdG, nitrotyrosine, showing its ability to inhibit oxidative damage. TREM1 in the lung tissue and improved lung regenerative capacity by enhancing Ki67, PCNA and Ang-1 protein expression. Together, these results proposed the protective properties of EGCG against LPS-induced ALI in may be attributed to the suppression of M1/M2 macrophages subtype ratio, KLF4 augmentation, lung cell regeneration and regulating oxidative damage in the LPS-induced murine ALI.

The Potential Health Care Costs And Resource Use Associated With COVID-19 In The United States

With the coronavirus disease 2019 (COVID-19) pandemic, one of the major concerns is the direct medical cost and resource use burden imposed on the US health care system. We developed a Monte Carlo simulation model that represented the US population and what could happen to each person who got infected. We estimated resource use and direct medical costs per symptomatic infection and at the national level, with various "attack rates" (infection rates), to understand the potential economic benefits of reducing the burden of the disease. A single symptomatic COVID-19 case could incur a median direct medical cost of $3,045 during the course of the infection alone. If 80 percent of the US population were to get infected, the result could be a median of 44.6 million hospitalizations, 10.7 million intensive care unit (ICU) admissions, 6.5 million patients requiring a ventilator, 249.5 million hospital bed days, and $654.0 billion in direct medical costs over the course of the pandemic. If 20 percent of the US population were to get infected, there could be a median of 11.2 million hospitalizations, 2.7 million ICU admissions, 1.6 million patients requiring a ventilator, 62.3 million hospital bed days, and $163.4 billion in direct medical costs over the course of the pandemic.