Definition and global epidemiology of pediatric acute respiratory distress syndrome

Acute respiratory distress syndrome: A review of ARDS across the life course

Acute respiratory distress syndrome (ARDS) is a multifactorial, inflammatory lung disease with significant morbidity and mortality that predominantly requires supportive care in its management. Although initially described in adult patients, the diagnostic definitions for ARDS have evolved over time to accurately describe this disease process in pediatric and, more recently, neonatal patients. The management of ARDS in each age demographic has converged in the application of lung-protective ventilatory strategies to mitigate the primary disease process and prevent its exacerbation by limiting ventilator-induced lung injury. However, differences arise in the preferred ventilatory strategies or adjunctive pulmonary therapies used to mitigate each type of ARDS. In this review, we compare and contrast the epidemiology, common etiologies, pathophysiology, diagnostic criteria, and outcomes of ARDS across the lifespan. Additionally, we discuss in detail the different management strategies used for each subtype of ARDS and spotlight how these strategies were applied to mitigate poor outcomes during the COVID-19 pandemic. This review is geared toward both clinicians and clinician-scientists as it not only summarizes the latest information on disease pathogenesis and patient management in ARDS across the lifespan but also highlights knowledge gaps for further investigative efforts. We conclude by projecting how future studies can fill these gaps in research and what improvements may be envisioned in the management of NARDS and PARDS based on the current breadth of literature on adult ARDS treatment strategies.

Loss of neutrophil Shp1 produces hemorrhagic and lethal acute lung injury

The acute respiratory distress syndrome (ARDS) is associated with significant morbidity and mortality and neutrophils are critical to its pathogenesis. Neutrophil activation is closely regulated by inhibitory tyrosine phosphatases including Src homology region 2 domain containing phosphatase-1 (Shp1). Here, we report that loss of neutrophil Shp1 in mice produced hyperinflammation and lethal pulmonary hemorrhage in sterile inflammation and pathogen-induced models of acute lung injury (ALI) through a Syk kinase-dependent mechanism. We observed large intravascular neutrophil clusters, perivascular inflammation, and excessive neutrophil extracellular traps in neutrophil-specific Shp1 knockout mice suggesting an underlying mechanism for the observed pulmonary hemorrhage. Targeted immunomodulation through the administration of a Shp1 activator (SC43) reduced agonist-induced reactive oxygen species in vitro and ameliorated ALI-induced alveolar neutrophilia and NETs in vivo. We propose that the pharmacologic activation of Shp1 has the potential to fine-tune neutrophil hyperinflammation that is central to the pathogenesis of ARDS.

Endothelial Glycocalyx Degradation Patterns in Sepsis-Associated Pediatric Acute Respiratory Distress Syndrome: A Single Center Retrospective Observational Study

BACKGROUND

Sepsis-associated destruction of the pulmonary microvascular endothelial glycocalyx (EGCX) creates a vulnerable endothelial surface, contributing to the development of acute respiratory distress syndrome (ARDS). Constituents of the EGCX shed into circulation, glycosaminoglycans and proteoglycans, may serve as biomarkers of endothelial dysfunction. We sought to define the patterns of plasma EGCX degradation products in children with sepsis-associated pediatric ARDS (PARDS), and test their association with clinical outcomes.

METHODS

We retrospectively analyzed a prospective cohort (2018-2020) of children (≥1 month to <18 years of age) receiving invasive mechanical ventilation for acute respiratory failure for ≥72 h. Children with and without sepsis-associated PARDS were selected from the parent cohort and compared. Blood was collected at time of enrollment. Plasma glycosaminoglycan disaccharide class (heparan sulfate, chondroitin sulfate, and hyaluronan) and sulfation subtypes (heparan sulfate and chondroitin sulfate) were quantified using liquid chromatography tandem mass spectrometry. Plasma proteoglycans (syndecan-1) were measured through an immunoassay.

RESULTS

Among the 39 mechanically ventilated children (29 with and 10 without sepsis-associated PARDS), sepsis-associated PARDS patients demonstrated higher levels of heparan sulfate (median 639 ng/mL [interquartile range, IQR 421-902] vs 311 [IQR 228-461]) and syndecan-1 (median 146 ng/mL [IQR 32-315] vs 8 [IQR 8-50]), both p = 0.01. Heparan sulfate subtype analysis demonstrated greater proportions of N-sulfated disaccharide levels among children with sepsis-associated PARDS (p = 0.01). Increasing N-sulfated disaccharide levels by quartile were associated with severe PARDS (n = 9/29) with the highest quartile including >60% of the severe PARDS patients (test for trend, p = 0.04). Higher total heparan sulfate and N-sulfated disaccharide levels were independently associated with fewer 28-day ventilator-free days in children with sepsis-associated PARDS (all p < 0.05).

CONCLUSIONS

Children with sepsis-associated PARDS exhibited higher plasma levels of heparan sulfate disaccharides and syndecan-1, suggesting that EGCX degradation biomarkers may provide insights into endothelial dysfunction and PARDS pathobiology.

Association between pediatric intensive care mortality and mechanical ventilation settings during extracorporeal membrane oxygenation for pediatric acute respiratory distress syndrome

The main objective of this study was to describe the current mechanical ventilation (MV) settings during extracorporeal membrane oxygenation (ECMO) for pediatric acute respiratory distress syndrome (P-ARDS) in six European centers. This is a retrospective observational cohort study performed in six European centers from January 2009 to December 2019. Children > 1 month to 18 years supported with ECMO for refractory P-ARDS were included. Collected data were as follows: patients' pre-ECMO medical condition, pre-ECMO adjunctive therapies for P-ARDS, pre-ECMO and during ECMO MV settings on day (D) 1, D3, D7, and D14 of ECMO, use of adjunctive therapies during ECMO, duration of ECMO, pediatric intensive care unit length of stay, and survival. A total of 255 patients with P-ARDS were included. The multivariate analysis showed that PEEP on D1 (OR = 1.13, 95% CI [1.03-1.24], p = 0.01); D3 (OR = 1.17, 95% CI [1.06-1.29], p = 0.001); and D14 (OR = 1.21, 95% CI [1.05-1.43], p = 0.02) and DP on D7 were significantly associated with higher odds of mortality (OR = 0.82, 95% CI [0.71-0.92], p = 0.001). Moreover, DP on D1 above 15 cmH2O (OR 2.23, 95% CI (1.09-4.71), p = 0.03) and native lung FiO2 above 60% on D14 (OR 10.36, 95% CI (1.51-116.15), p = 0.03) were significantly associated with higher odds of mortality.   Conclusion: MV settings during ECMO for P-ARDS varied among centers; however, use of high PEEP levels during ECMO was associated with higher odds of mortality as well as a DP above 15 cmH2O and a native lung FiO2 above 60% on D14 of ECMO. What is Known: • Invasive ventilation settings are well defined for pediatric acute respiratory distress syndrome; however, once the children required an extracorporeal respiratory support, there is no recommendation how to set the mechanical ventilator. • Impact of invasive ventilator during extracorporeal respiratory support ad only been during the first days of this support but the effects of these settings later in the assistance are not described. What is New: • It seems to be essential to early decrease FiO2 on native lung once the ECMO flow allows an efficient oxygenation. • Tight control to limit the driving pressure at 15 cmH20 during ECMO run seems to be associated with better survival rate.

Interrater Reliability of the 2015 Pediatric Acute Lung Injury Consensus Conference Criteria for Pediatric ARDS

BACKGROUND

Diagnostic guidelines for pediatric ARDS (PARDS) were developed at the 2015 Pediatric Acute Lung Injury Consensus Conference (PALICC). Although this was an improvement in creating pediatric-specific diagnostic criteria, there remains potential for variability in identification of PARDS.

RESEARCH QUESTION

What is the interrater reliability of the 2015 PALICC criteria for diagnosing moderate to severe PARDS? What clinical criteria and patient factors are associated with diagnostic disagreements?

STUDY DESIGN AND METHODS

Patients with acute hypoxic respiratory failure admitted from 2016 to 2021 who received invasive mechanical ventilation were retrospectively reviewed by two pediatric ICU physicians. Reviewers evaluated whether the patient met the 2015 PALICC definition of moderate to severe PARDS and rated their diagnostic confidence. Interrater reliability was measured using Gwet's agreement coefficient.

RESULTS

Thirty-seven of 191 encounters had a diagnostic disagreement. Interrater reliability was substantial (Gwet's agreement coefficient, 0.74; 95% CI, 0.65-0.83). Disagreements were caused by different interpretations of chest radiographs (56.8%), ambiguity in origin of pulmonary edema (37.8%), or lack of clarity if patient's current condition was significantly different from baseline (27.0%). Disagreement was more likely in patients who were chronically ventilated (OR, 4.66; 95% CI, 2.16-10.08; P < .001), had a primary cardiac admission diagnosis (OR, 3.36; 95% CI, 1.18-9.53; P = .02), or underwent cardiothoracic surgery during the admission (OR, 4.90; 95% CI, 1.60-15.00; P = .005). Reviewers were at least moderately confident in their decision 73% of the time; however, they were less likely to be confident if the patient had cardiac disease or chronic respiratory failure.

INTERPRETATION

The interrater reliability of the 2015 PALICC criteria for diagnosing moderate to severe PARDS in this cohort was substantial, with diagnostic disagreements commonly caused by differences in chest radiograph interpretations. Patients with cardiac disease or chronic respiratory failure were more vulnerable to diagnostic disagreements. More guidance is needed on interpreting chest radiographs and diagnosing PARDS in these subgroups.

Cardiac dysfunction in severe pediatric acute respiratory distress syndrome: the right ventricle in search of the right therapy

Severe acute respiratory distress syndrome in children, or PARDS, carries a high risk of morbidity and mortality that is not fully explained by PARDS severity alone. Right ventricular (RV) dysfunction can be an insidious and often under-recognized complication of severe PARDS that may contribute to its untoward outcomes. Indeed, recent evidence suggest significantly worse outcomes in children who develop RV failure in their course of PARDS. However, in this narrative review, we highlight the dearth of evidence regarding the incidence of and risk factors for PARDS-associated RV dysfunction. While we wish to draw attention to the absence of available evidence that would inform recommendations around surveillance and treatment of RV dysfunction during severe PARDS, we leverage available evidence to glean insights into potentially helpful surveillance strategies and therapeutic approaches.

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.

Sepsis-related pediatric acute respiratory distress syndrome: A multicenter prospective cohort study

OBJECTIVES

This study aimed to compare the risk factors and outcomes for organ dysfunction between sepsis-related Pediatric acute respiratory distress syndrome (PARDS) and nonsepsis PARDS.

METHODS

We prospective cohort recruited intubated patients with PARDS at four tertiary care centers in Thailand. The baseline characteristics, mechanical ventilation, fluid balance, and clinical outcomes were collected. The primary outcome was organ dysfunction.

RESULTS

One hundred and thirty-two mechanically ventilated children with PARDS were included in the study. The median age was 29 months and 53.8% were male. The mortality rate was 22.7% and organ dysfunction was 45.4%. There were 26 (19.7%) and 106 (80.3%) patients who were classified into sepsis-related PARDS and nonsepsis PARDS, respectively. Sepsis-related PARDS patients had a significantly higher incidence of acute kidney injury (30.8% vs. 13.2%, P = 0.041), septic shock (88.5% vs. 32.1%, P < 0.001), organ dysfunction (84.6% vs. 35.8%, P < 0.001), and death (42.3% vs. 17.9%, P = 0.016) than nonsepsis PARDS group. Multivariate analysis adjusted for clinical variables showed that sepsis-related PARDS and percentage of fluid overload were significantly associated with organ dysfunction (odds ratio [OR] 11.414; 95% confidence interval [CI] 1.40892.557, P = 0.023 and OR 1.169; 95% CI 1.0121.352, P = 0.034).

CONCLUSIONS

Sepsis-related PARDS patients had more severe illness, organ dysfunction, and mortality than nonsepsis PARDS patients. The higher percentage of fluid overload and presentation of sepsis was the independent risk factor of organ dysfunction in PARDS patients.

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.

Effects of microRNA-101-3p on predicting pediatric acute respiratory distress syndrome and its role in human alveolar epithelial cell

Pediatric acute respiratory distress syndrome (PARDS) is a severe form of respiratory failure associated with high mortality among children. The objective of this study is reported to explore the clinical function and molecular roles of microRNA-101-3p (miR-101-3p) in PARDS. The levels of miR-101-3p and mRNA levels of SRY-related high-mobility group box 9 (Sox9) were measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Additionally, the diagnostic role of miR-101-3p was identified by using the Receiver operating characteristic (ROC) curve. The cell proliferation and apoptosis were examined through Cell Counting Kit-8 (CCK-8) assay and flow cytometry. To detect inflammation in cells, enzyme-linked immunosorbent assays (ELISA) were performed. The target gene of miR-101-3p was confirmed through data obtained from the luciferase activity. In patients with PARDS, miR-101-3p expression was decreased. Moderate and severe PARDS patients had lower levels of miR-101-3p than mild PARDS patients. The inflammatory progression was related to the aberrant expression of miR-101-3p in all PARDS children. MiR-101-3p was highly predictive for the detection of children with PARDS. In addition, miR-101-3p might protect A549 cells from abnormal proliferation, apoptosis, and inflammation caused by lipopolysaccharide (LPS). Sox9 might be a target gene of miR-101-3p and increased mRNA expression of Sox9 in LPS-treated A549 cells was inhibited by overexpression of miR-101-3p. Ultimately, this study suggested that reduced expression of miR-101-3p plays a role in PARDS, providing a novel angle to study the disease.

Comparison of the OI and PaO2 /FiO2 score in evaluating PARDS requiring mechanical ventilation

AIM

To examine the differences between oxygenation index (OI) and arterial partial pressure of oxygen to the fraction of inspired oxygen (PaO₂ /FiO₂ , [P/F]) in evaluating the severity of pediatric acute respiratory distress syndrome (PARDS).

METHODS

The severity of PARDS was graded by using the OI score and P/F ratio, respectively. The data including clinical indexes and prognosis indicators were recorded and analyzed.

RESULTS

During the 3-year study period, there were significant differences between OI and P/F scores in the severity grading of PARDS patients (p < .05). However, in severe diseases, both the scorings of OI and P/F were consistent (24.6% vs. 25.6%). The OI scores appeared more accurate when compared with P/F in the correlation between them and the pediatric critical illness score, multiple organ dysfunction syndromes (MODS), pressure indexes of ventilators and patients' prognosis. In the receiver operating characteristic curve, the critical values of OI and P/F were 8.42 and 144.71. Area under the curve of them were 0.839 and 0.853. The sensitivity values were both 0.854. The specificity values were 0.584 and 0.602.

CONCLUSIONS

The OI and P/F were consistent in designating patients with severe PARDS. Among patients with mild to moderate diseases, the P/F could still be used for rapid determination given its simple calculation. Combined with the prognostic factors, the OI score was more accurate.

Oxyberberine Prevented Lipopolysaccharide-Induced Acute Lung Injury through Inhibition of Mitophagy

Acute lung injury (ALI) is a serious respiratory syndrome characterized with uncontrolled inflammatory response. Oxyberberine has strong potential for clinical usage since it showed strong anti-inflammatory, antifungal, and antiarrhythmic effects in various diseases. In the present study, we evaluated whether oxyberberine can inhibit lipopolysaccharide- (LPS-) induced ALI in vivo and further evaluated the possible involvement of mitophagy in vitro by using A549 cells, a human lung epithelial cell line. Our in vivo study shows that oxyberberine significantly inhibited LPS-induced lung pathological injury and lung edema, as indicated by the changes in lung wet/dry ratio and total protein levels in the BALF in mice. Moreover, oxyberberine inhibited inflammation, as indicated by the changes of neutrophil accumulation and production of proinflammatory cytokines including tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and IL-6 in both the lung and bronchoalveolar lavage fluid (BALF) in ALI mice. Our in vitro study shows that LPS significantly decreased the protein level of mitochondrial proteins, including cytochrome c oxidase subunit IV (COX IV), p62, and mitofusin-2 (Mfn2) in A549 cells. In addition, LPS induced significant Parkin1 translocation from cytoplasm to mitochondria. These changes were significantly inhibited by oxyberberine. Notably, the inhibitory effect of oxyberberine was almost totally lost in the presence of lysosome fusion inhibitor bafilomycin A1 (Baf), a mitophagy inhibitor. In conclusion, the present study demonstrated that oxyberberine alleviated LPS-induced inflammation in ALI via inhibition of Parkin-mediated mitophagy.

Vaccine-associated enhanced disease: Case definition and guidelines for data collection, analysis, and presentation of immunization safety data

This is a Brighton Collaboration Case Definition of the term “Vaccine Associated Enhanced Disease” to be utilized in the evaluation of adverse events following immunization. The Case Definition was developed by a group of experts convened by the Coalition for Epidemic Preparedness Innovations (CEPI) in the context of active development of vaccines for SARS-CoV-2 vaccines and other emerging pathogens. The case definition format of the Brighton Collaboration was followed to develop a consensus definition and defined levels of certainty, after an exhaustive review of the literature and expert consultation. The document underwent peer review by the Brighton Collaboration Network and by selected Expert Reviewers prior to submission.

Acute respiratory distress syndrome (ARDS) as an adverse event following immunization: Case definition & guidelines for data collection, analysis, and presentation of immunization safety data

This is a Brighton Collaboration Case Definition of the term “Acute Respiratory Distress Syndrome – ARDS” to be utilized in the evaluation of adverse events following immunization. The Case Definition was developed by a group of experts convened by the Coalition for Epidemic Preparedness Innovations (CEPI) in the context of active development of vaccines for SARS-CoV-2 vaccines and other emerging pathogens. The case definition format of the Brighton Collaboration was followed to develop a consensus definition and defined levels of certainty, after an exhaustive review of the literature and expert consultation. The document underwent peer review by the Brighton Collaboration Network and by selected Expert Reviewers prior to submission. The comments of the reviewers were taken into consideration and edits incorporated in this final manuscript.