Paediatric acute respiratory distress syndrome incidence and epidemiology (PARDIE): an international, observational study

Thrombomodulin is associated with increased mortality and organ failure in mechanically ventilated children with acute respiratory failure: biomarker analysis from a multicenter randomized controlled trial

BACKGROUND

Acute respiratory failure (ARF) can progress to acute respiratory distress syndrome and death. Biomarkers may allow for risk stratification and prognostic enrichment in ARF. Thrombomodulin (TM) is a transmembrane antithrombotic mediator expressed in endothelial cells. It is cleaved into its soluble form (sTM) during inflammation and vascular injury. Levels of sTM correlate with inflammation and end organ dysfunction.

METHODS

This was a prospective observational study of 432 patients aged 2 weeks-17 years requiring invasive mechanical ventilation. It was ancillary to the multicenter clinical trial, Randomized Evaluation of Sedation Titration for Respiratory Failure (RESTORE). After consent, patients had up to 3 plasma samples collected at 24-h intervals within 5 days after intubation. sTM was assayed by ELISA. The Hazard ratio (HR) for 90-day mortality was determined by Cox regression. Mixed effect models (MEM) were used to test for association with extrapulmonary multiorgan failure (MOF) and oxygenation index (OI). Age, race, sex and PRISM-III scores were used as confounding variables for multivariable analyses.

RESULTS

sTM values ranged from 16.6 to 670.9 ng/ml within 5 days after intubation. Higher sTM was associated with increased 90-day mortality (n = 432, adjusted HR = 1.003, p = 0.02) and worse OI in the first 5 days after intubation (n = 252, Estimate = 0.02, p < 0.01). Both initial and slope of sTM were associated with increased extrapulmonary MOF in unadjusted and adjusted analyses (Intercept, Estimate = 0.003, p < 0.0001; and slope, Estimate = 0.01, p = 0.0009, n = 386).

CONCLUSIONS

Plasma sTM is associated with mortality, severity of hypoxic respiratory failure and worsening extrapulmonary MOF in children with ARF. This suggests a role of vascular injury in the pathogenesis of ARF and provides potential applicability towards targeted therapies.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT00814099 . In healthy lung endothelium, thrombomodulin (TM) recruits thrombin to activate Protein-C (PC/APC), that inhibits plasminogen activator-1 (PAI-1) and thrombosis. In inflamed and damaged endothelium, TM is cleaved into its soluble form (sTM), precluding its usual regulation of thrombosis. In this study, we measured plasma sTM levels in pediatric patients with respiratory failure and found that sTM correlated with mortality and other clinical markers of poor outcomes.

Point-of-Care Lung Ultrasound to Diagnose the Etiology of Acute Respiratory Failure at Admission to the PICU

OBJECTIVES

Determine the sensitivity and specificity of point-of-care lung ultrasound in identifying the etiology of acute respiratory failure at admission to the PICU.

DESIGN

Prospective observational study.

SETTING

Tertiary PICU.

PATIENTS

Children older than 37 weeks gestational age and less than or equal to 18 years old admitted to the PICU with acute respiratory failure from December 2018 to February 2020.

INTERVENTION

Point-of-care lung ultrasound performed within 14 hours of admission to the PICU by physicians blinded to patient history and clinical course. Two physicians, blinded to all clinical information, independently interpreted the point-of-care lung ultrasound and then established a consensus diagnosis (ultrasound diagnosis). The ultrasound diagnosis was compared with an independent, standardized review of the medical record following hospital discharge (final diagnosis).

MEASUREMENTS AND RESULTS

Eighty-eight patients were enrolled in the study. Forty-eight patients had a final diagnosis of bronchiolitis/viral pneumonitis (55%), 29 had pneumonia (33%), 10 had status asthmaticus (11%), and one was excluded because of an inability to differentiate the final diagnosis. Point-of-care lung ultrasound correctly identified the etiology of acute respiratory failure in 56% of patients (49/87; 95% CI, 46-66%). It identified bronchiolitis/viral pneumonitis with 44% sensitivity (95% CI, 0.31-0.58) and 74% specificity (95% CI, 0.59-0.85), pneumonia with 76% sensitivity (95% CI, 0.58-0.88) and 67% specificity (95% CI 0.54-0.78), and status asthmaticus with 60% sensitivity (95% CI, 0.31-0.83) and 88% specificity (95% CI, 0.79-0.94).

CONCLUSIONS

In contrast to literature demonstrating high utility differentiating the cause of acute respiratory failure in adults, blinded point-of-care lung ultrasound demonstrates moderate sensitivity and specificity in identifying the etiology of pediatric acute respiratory failure at admission to the PICU among children with bronchiolitis, pneumonia, and status asthmaticus.

Ventilator-Weaning Pathway Associated With Decreased Ventilator Days in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

There is limited evidence on the impact of protocolized ventilator weaning in pediatric acute respiratory distress syndrome, despite utilization in clinical trials and clinical care. We aimed to determine whether protocolized ventilator weaning shortens mechanical ventilation duration and PICU length of stay in pediatric acute respiratory distress syndrome survivors.

DESIGN

Secondary analysis of a prospective pediatric acute respiratory distress syndrome (Berlin definition) cohort from July 2011 to June 2019 analyzed using interrupted time series analysis pre- and postimplementations of a ventilator-weaning pathway. We compared duration of invasive ventilation and PICU length of stay in survivors before and after implementation of a ventilator-weaning pathway. We excluded PICU nonsurvivors and subjects with greater than 100 ventilator days.

SETTING

Large academic tertiary-care PICU.

PATIENTS

Children with acute respiratory distress syndrome who survived to PICU discharge with less than or equal to 100 days of invasive mechanical ventilation.

INTERVENTIONS

Implementation of a ventilator-weaning pathway on May 2016.

MEASUREMENTS AND MAIN RESULTS

Of 723 children with acute respiratory distress syndrome, 132 subjects died and six subjects with ventilation greater than 100 days were excluded. Of the remaining 585 subjects, 375 subjects had acute respiratory distress syndrome prior to pathway intervention and 210 after. Patients in the preintervention epoch were younger, more likely to have infectious acute respiratory distress syndrome, and had increased use of alternative ventilator modes. Pathway adoption was rapid and sustained. Controlling for temporality, pathway implementation was associated with a decrease of a median 3.6 ventilator days (95% CI, -5.4 to -1.7; p < 0.001). There was no change in the reintubation rates. Results were robust to multiple sensitivity analyses adjusting for confounders.

CONCLUSIONS

Ventilator-weaning pathway implementation shortened invasive ventilation duration in pediatric acute respiratory distress syndrome survivors with no change in reintubation. The effect size of this intervention was comparable with those targeted in acute respiratory distress syndrome trials.

Treatment of the lung injury of drowning: a systematic review

Background

Drowning is a cause of significant global mortality. The mechanism of injury involves inhalation of water, lung injury and hypoxia. This systematic review addressed the following question: In drowning patients with lung injury, what is the evidence from primary studies regarding treatment strategies and subsequent patient outcomes?

Methods

The search strategy utilised PRISMA guidelines. Databases searched were MEDLINE, EMBASE, CINAHL, Web of Science and SCOPUS. There were no restrictions on publication date or age of participants. Quality of evidence was evaluated using GRADE methodology.

Results

Forty-one papers were included. The quality of evidence was very low. Seventeen papers addressed the lung injury of drowning in their research question and 24 had less specific research questions, however included relevant outcome data. There were 21 studies regarding extra-corporeal life support, 14 papers covering the theme of ventilation strategies, 14 addressed antibiotic use, seven papers addressed steroid use and five studies investigating diuretic use. There were no clinical trials. One retrospective comparison of therapeutic strategies was found. There was insufficient evidence to make recommendations as to best practice when supplemental oxygen alone is insufficient. Mechanical ventilation is associated with barotrauma in drowning patients, but the evidence predates the practice of lung protective ventilation. There was insufficient evidence to make recommendations regarding adjuvant therapies.

Conclusions

Treating the lung injury of drowning has a limited evidentiary basis. There is an urgent need for comparative studies of therapeutic strategies in drowning.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03687-2.

Inflammatory Biomarkers Are Associated With a Decline in Functional Status at Discharge in Children With Acute Respiratory Failure: An Exploratory Analysis

Supplemental Digital Content is available in the text.

To evaluate the link between early acute respiratory failure and functional morbidity in survivors using the plasma biomarkers interleukin-8, interleukin-1 receptor antagonist, thrombomodulin, and plasminogen activator inhibitor-1. We hypothesized that children with acute respiratory failure with higher levels of inflammation would have worse functional outcomes at discharge, as measured by Pediatric Overall Performance Category.

Machine Learning-Based Discovery of a Gene Expression Signature in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To identify differentially expressed genes and networks from the airway cells within 72 hours of intubation of children with and without pediatric acute respiratory distress syndrome. To test the use of a neutrophil transcription reporter assay to identify immunogenic responses to airway fluid from children with and without pediatric acute respiratory distress syndrome.

DESIGN

Prospective cohort study.

SETTING

Thirty-six bed academic PICU.

PATIENTS

Fifty-four immunocompetent children, 28 with pediatric acute respiratory distress syndrome, who were between 2 days to 18 years old within 72 hours of intubation for acute hypoxemic respiratory failure.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We applied machine learning methods to a Nanostring transcriptomics on primary airway cells and a neutrophil reporter assay to discover gene networks differentiating pediatric acute respiratory distress syndrome from no pediatric acute respiratory distress syndrome. An analysis of moderate or severe pediatric acute respiratory distress syndrome versus no or mild pediatric acute respiratory distress syndrome was performed. Pathway network visualization was used to map pathways from 62 genes selected by ElasticNet associated with pediatric acute respiratory distress syndrome. The Janus kinase/signal transducer and activator of transcription pathway emerged. Support vector machine performed best for the primary airway cells and the neutrophil reporter assay using a leave-one-out cross-validation with an area under the operating curve and 95% CI of 0.75 (0.63-0.87) and 0.80 (0.70-1.0), respectively.

CONCLUSIONS

We identified gene networks important to the pediatric acute respiratory distress syndrome airway immune response using semitargeted transcriptomics from primary airway cells and a neutrophil reporter assay. These pathways will drive mechanistic investigations into pediatric acute respiratory distress syndrome. Further studies are needed to validate our findings and to test our models.

Use of Negative Pressure Ventilation in Pediatric Critical Care: Experience in 56 PICUs in the Virtual Pediatric Systems Database (2009-2019)

OBJECTIVES

Negative pressure ventilation may be more physiologic than positive pressure ventilation, but data describing negative pressure ventilation use in the PICU are limited. We aimed to describe the epidemiology and outcomes of PICU patients receiving negative pressure ventilation.

DESIGN

Descriptive analysis of a large, quality-controlled multicenter database.

SETTING

Fifty-six PICUs in the Virtual Pediatric Systems database who reported use of negative pressure ventilation.

PATIENTS

Children admitted to a participating PICU between 2009 and 2019 who received negative pressure ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among 788 subjects, 71% were less than 2 years old, and 45% had underlying health conditions. Two concurrent aspiration events were the only adverse events reported. After excluding one over-represented center, the 3 years with the most negative pressure ventilation usage were 2017-2019 (all > 25 cases/yr and ≥ 13 centers reporting usage). Among those 187 children, the most common primary diagnoses were bronchiolitis and cardiac disease (both 15.5%), 24.1% required endotracheal intubation after negative pressure ventilation, and 9.1% died.

CONCLUSIONS

Negative pressure ventilation is being used in many PICUs, most commonly for pulmonary infections or cardiac disease, in children with high rates of subsequent intubation and mortality and with few documented adverse events. Use at individual centers is rare but increasing, suggesting need for prospective collaboration to better evaluate the role of negative pressure ventilation in the PICU.

Paediatrics: how to manage acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is a significant cause of mortality and morbidity amongst critically ill children. The purpose of this narrative review is to provide an up-to-date review on the evaluation and management of paediatric ARDS (PARDS).

Methods

A PubMed search was performed with Clinical Queries using the key term "acute respiratory distress syndrome". The search strategy included clinical trials, meta-analyses, randomized controlled trials, observational studies and reviews. Google, Wikipedia and UpToDate were also searched to enrich the review. The search was restricted to the English literature and children.

Discussion

Non-invasive positive pressure ventilation, lung-protective ventilation strategies, conservative fluid management and adequate nutritional support all have proven efficacy in the management of PARDS. The Pediatric Acute Lung Injury Consensus Conference recommends the use of corticosteroids, high-frequency oscillation ventilation and inhaled nitric oxide in selected scenarios. Partial liquid ventilation and surfactant are not considered efficacious based on evidence from clinical trials.

Conclusion

PARDS is a serious but relatively rare cause of admission into the paediatric intensive care unit and is associated with high mortality. Non-invasive positive pressure ventilation, lung-protective ventilation strategies, conservative fluid management and adequate nutrition are advocated. As there has been a lack of progress in the management of PARDS in recent years, further well-designed, large-scale, randomized controlled trials in this field are urgently needed.

Invasive and noninvasive ventilation strategies for acute respiratory failure in children with coronavirus disease 2019

PURPOSE OF REVIEW

Severe Acute Respiratory Syndrome Coronavirus 2 presents as symptomatic coronavirus disease 2019 (COVID-19) disease in susceptible patients. Severe pediatric COVID-19 disease is rare, limiting potential data accumulation on associated respiratory failure in children. Pediatric intensivists and pulmonologists managing COVID-19 patients look to adult guidelines and pediatric-specific consensus statements to guide management. The purpose of this article is to review the current literature and recommended strategies for the escalation of noninvasive and invasive respiratory support for acute respiratory failure associated with COVID-19 disease in children.

RECENT FINDINGS

There are no prospective studies comparing COVID-19 treatment strategies in children. Adult and pediatric ventilation management interim guidance is based on evidence-based guidelines in non-COVID acute respiratory distress syndrome, with considerations of (1) noninvasive positive pressure ventilation versus high-flow nasal cannula and (2) high versus lower positive end expiratory pressure strategies related to lung compliance and potential lung recruitability.

SUMMARY

Management of acute respiratory failure from COVID-19 requires individualized titration of noninvasive and invasive ventilation modalities with consideration of preserved or compromised pulmonary compliance. Research regarding best practices in the management of pediatric severe COVID-19 with respiratory failure is lacking and is acutely needed as the pandemic surges and vaccination of the pediatric population will be delayed compared to adults.

Multisystem inflammatory syndrome in children: a microcosm of challenges and opportunities for translational bioinformatics in pediatric research

PURPOSE OF REVIEW

Despite significant progress in our understanding and clinical management of multisystem inflammatory syndrome in children (MIS-C), significant challenges remain. Here, we review recently published studies on the clinical diagnosis, risk stratification, and treatment of MIS-C, highlighting key gaps in research progress that are a microcosm for challenges in translational pediatric research. We then discuss potential solutions in the realm of translational bioinformatics.

RECENT FINDINGS

Current case definitions are inconsistent and do not capture the underlying pathophysiology of MIS-C, which remains poorly understood. Although overall mortality is low, some patients rapidly decompensate, and a test to identify those at risk for severe outcomes remains an unmet need. Treatment consists of various combinations of immunoglobulins, corticosteroids, and biologics, based on extrapolated data and expert opinion, while the benefits remain unclear as we await the completion of clinical trials.

SUMMARY

The small size and heterogeneity of the pediatric population contribute to unmet needs because of financial and logistical constraints of the current research infrastructure focused on eliminating most sources of heterogeneity, leading to ungeneralizable results. Data sharing and meta-analysis of gene expression shows promise to accelerate progress in the field of MIS-C as well as other childhood diseases beyond the current pandemic.

Predicting Mortality in Children With Pediatric Acute Respiratory Distress Syndrome: A Pediatric Acute Respiratory Distress Syndrome Incidence and Epidemiology Study

Supplemental Digital Content is available in the text.

Pediatric acute respiratory distress syndrome is heterogeneous, with a paucity of risk stratification tools to assist with trial design. We aimed to develop and validate mortality prediction models for patients with pediatric acute respiratory distress syndrome.

Utility of Driving Pressure and Mechanical Power to Guide Protective Ventilator Settings in Two Cohorts of Adult and Pediatric Patients With Acute Respiratory Distress Syndrome: A Computational Investigation

OBJECTIVES

Mechanical power and driving pressure have been proposed as indicators, and possibly drivers, of ventilator-induced lung injury. We tested the utility of these different measures as targets to derive maximally protective ventilator settings.

DESIGN

A high-fidelity computational simulator was matched to individual patient data and used to identify strategies that minimize driving pressure, mechanical power, and a modified mechanical power that removes the direct linear, positive dependence between mechanical power and positive end-expiratory pressure.

SETTING

Interdisciplinary Collaboration in Systems Medicine Research Network.

SUBJECTS

Data were collected from a prospective observational cohort of pediatric acute respiratory distress syndrome from the Children's Hospital of Philadelphia (n = 77) and from the low tidal volume arm of the Acute Respiratory Distress Syndrome Network tidal volume trial (n = 100).

INTERVENTIONS

Global optimization algorithms evaluated more than 26.7 million changes to ventilator settings (approximately 150,000 per patient) to identify strategies that minimize driving pressure, mechanical power, or modified mechanical power.

MEASUREMENTS AND MAIN RESULTS

Large average reductions in driving pressure (pediatric: 23%, adult: 23%), mechanical power (pediatric: 44%, adult: 66%), and modified mechanical power (pediatric: 61%, adult: 67%) were achievable in both cohorts when oxygenation and ventilation were allowed to vary within prespecified ranges. Reductions in driving pressure (pediatric: 12%, adult: 2%), mechanical power (pediatric: 24%, adult: 46%), and modified mechanical power (pediatric: 44%, adult: 46%) were achievable even when no deterioration in gas exchange was allowed. Minimization of mechanical power and modified mechanical power was achieved by increasing tidal volume and decreasing respiratory rate. In the pediatric cohort, minimum driving pressure was achieved by reducing tidal volume and increasing respiratory rate and positive end-expiratory pressure. The Acute Respiratory Distress Syndrome Network dataset had limited scope for further reducing tidal volume, but driving pressure was still significantly reduced by increasing positive end-expiratory pressure.

CONCLUSIONS

Our analysis identified different strategies that minimized driving pressure or mechanical power consistently across pediatric and adult datasets. Minimizing standard and alternative formulations of mechanical power led to significant increases in tidal volume. Targeting driving pressure for minimization resulted in ventilator settings that also reduced mechanical power and modified mechanical power, but not vice versa.

The Impact of Preintubation Noninvasive Ventilation on Outcomes in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

There is evidence that noninvasive ventilation decreases the need for invasive mechanical ventilation. However, children with pediatric acute respiratory distress syndrome who fail noninvasive ventilation may have worse outcomes than those who are intubated without exposure to noninvasive ventilation. Our objective was to evaluate the impact of preintubation noninvasive ventilation on children with pediatric acute respiratory distress syndrome.

DESIGN

Secondary analysis of data from the Randomized Evaluation of Sedation Titration for Respiratory Failure trial.

SETTING

Thirty-one PICUs in the United States.

PATIENTS

Children 2 weeks to 17 years old with pediatric acute respiratory distress syndrome receiving invasive mechanical ventilation, excluding those admitted with tracheostomies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 2,427 subjects receiving invasive mechanical ventilation, preintubation noninvasive ventilation was used in 995 (41%). Compared with subjects without preintubation noninvasive ventilation use, subjects with preintubation noninvasive ventilation use were more likely to have a history of seizures (10% vs 8%; p = 0.04) or cancer (11% vs 6%; p < 0.001) and have moderate or severe pediatric acute respiratory distress syndrome by the end of their first full day of invasive mechanical ventilation (68% vs 60%; p < 0.001). Adjusting for age, severity of illness on PICU admission, and baseline functional status, preintubation noninvasive ventilation use resulted in longer invasive mechanical ventilation duration (median 7.0 vs 6.0 d), longer PICU (10.8 vs 8.9 d), and hospital (17 vs 14 d) lengths of stay, and higher 28-day (5% vs 4%) and 90-day (8% vs 5%) inhospital mortalities (all comparisons p < 0.001). Longer duration of noninvasive ventilation before intubation was associated with worse outcomes.

CONCLUSIONS

In children with pediatric acute respiratory distress syndrome, preintubation noninvasive ventilation use is associated with worse outcomes when compared with no preintubation noninvasive ventilation use. These data can be used to inform the design of clinical studies to evaluate best noninvasive ventilation practices in children with pediatric acute respiratory distress syndrome.

Bridging the Gap Between Intensivists and Primary Care Clinicians in Extracorporeal Membrane Oxygenation for Respiratory Failure in Children: A Review

IMPORTANCE

Extracorporeal membrane oxygenation (ECMO) is a form of advanced life support that may be used in children with refractory respiratory or cardiac failure. While it is required infrequently, in the US, ECMO is used to support childhood respiratory failure as often as children receive kidney or heart transplants. ECMO is complex, resource intensive, and potentially lifesaving, but it is also associated with risks of short-term complications and long-term adverse effects, most importantly with neurodevelopmental outcomes that are relevant to all pediatric clinicians, even those remote from the child's critical illness.

OBSERVATIONS

The 2009 influenza A(H1N1) pandemic, along with randomized clinical trials of adult respiratory ECMO support and conventional management, have catalyzed sustained growth in the use of ECMO. The adult trials built on earlier neonatal ECMO randomized clinical trials that demonstrated improved survival in severe perinatal lung disease. For children outside of the neonatal period, there appear to have been no respiratory ECMO clinical trials. Applying evidence from adult respiratory failure or perinatal lung disease to children outside the neonatal period has important potential pitfalls. For these children, the underlying diseases and risks of ECMO are different. Despite these differences, both neonates and older children are at risk of neurologic complications, such as intracranial hemorrhage, ischemic stroke, and seizures, and those complications may contribute to adverse neurodevelopmental outcomes. Without specific screening, subtle neurodevelopmental impairments may be missed, but when they are identified, children have the opportunity to receive therapy to optimize long-term development.

CONCLUSIONS AND RELEVANCE

All pediatric clinicians should be aware not only of the potential benefits and complications of ECMO but also that survivors need effective screening, support, and follow-up.

High-Frequency Jet Ventilation in Neonatal and Pediatric Subjects: A Narrative Review

High-frequency ventilation is commonly utilized with neonates and with children with severe respiratory failure. Both high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) are used extensively in neonates. HFJV can also be used in older, larger children. The purpose of this narrative review is to discuss the physiologic principles behind HFJV, examine the evidence supporting its use in neonatal and pediatric ICUs, give meaningful guidance for clinical application, and highlight potential areas for future research.

Epidemiology of Critical Interventions in Children With Traumatic Intracranial Hemorrhage

OBJECTIVE

To estimate rates of critical medical and neurosurgical interventions and resource utilization for children with traumatic intracranial hemorrhage (ICH).

METHODS

This was a retrospective study of children younger than 18 years hospitalized in 1 of 35 hospitals in the Pediatric Health Information System from 2009 to 2019 for ICH. We defined critical intervention as a critical medical (hyperosmotic agents and intubation) or neurosurgical intervention. We determined rates of critical interventions, intensive care unit (ICU) admission, and repeat neuroimaging. We used hierarchical logistic regression to identify high-level factors associated with undergoing critical interventions, controlling for hospital-level effects.

RESULTS

There were 12,714 children with ICH included in the study. Median (interquartile range) age was 4.3 (0.7-11.0) years. Twelve percent (n = 1470) of children underwent a critical clinical intervention. Critical medical interventions occurred in 10% (n = 1219), and neurosurgical interventions occurred in 3% (n = 419). Intensive care unit admission occurred in 44% (n = 5565), whereas repeat neuroimaging occurred in 40% (n = 5072). Among ICU patients, 79% (n = 4366) did not undergo a critical intervention. Of the 11,244 children with no critical interventions, 39% (n = 4366) underwent ICU admission, and 37% (n = 4099) repeat neuroimaging. After controlling for hospital, children with isolated subdural (P = 0.013) and isolated subarachnoid (P < 0.001) hemorrhage were less likely to receive critical interventions.

CONCLUSIONS

Critical medical interventions occurred in 10% of children with ICH, and neurosurgical interventions occurred in 3%. Intensive care unit admission and repeat neuroimaging are common, even among those who did not undergo critical interventions. Selective utilization of ICU admission and repeat neuroimaging in children who are at low risk of requiring critical interventions could improve overall quality of care and decrease unnecessary resource utilization.

Trends and variation in repeat neuroimaging for children with traumatic intracranial hemorrhage

OBJECTIVES

We aimed to determine trends and institutional variation in repeat neuroimaging in children with traumatic intracranial hemorrhage and to identify factors associated with neuroimaging modality (subsequent magnetic resonance imaging [MRI] vs computed tomography [CT]).

METHODS

We conducted a retrospective cross-sectional study of 35 hospitals in the Pediatric Health Information System database. We included children <18 years of age hospitalized from 2010-2019 with intracranial hemorrhage and who underwent a brain CT. We calculated repeat neuroimaging rates by modality and used regression analyses to examine temporal trends. We used hierarchical logistic regression to identify factors associated with subsequent MRI versus repeat CT, controlling for hospital.

RESULTS

We identified 12,714 children with intracranial hemorrhage, of which 5072 with repeat neuroimaging were studied. Of the 5072 children with repeat neuroimaging, repeat CT was performed in 67.6% (n = 3429) and subsequent MRI in 32.4% (n = 1643). Overall repeat neuroimaging with either a CT or MRI remained similar from 2010-2019 (P = 0.431); however, repeat CT scans significantly decreased (P = 0.001); whereas, MRIs significantly increased (P < 0.001). Repeat neuroimaging by hospital ranged from 20%-80%. After controlling for institution, subsequent MRI was more likely to be used in younger children and children who did not receive hyperosmotic agents, neurosurgical interventions, or intensive care unit admission (all P-values <0.001).

CONCLUSIONS

We found that repeat neuroimaging rates for children with intracranial hemorrhage vary substantially by institution. We also found that although MRI was increasingly used to re-image these children, overall repeat neuroimaging rates (CT or MRI) have not decreased over the past decade. Future work to implement optimal utilization of neuroimaging in these children is needed.

Rest ventilator management in children on veno-venous extracorporeal membrane oxygenation

BACKGROUND

We aimed to use the Extracorporeal Life Support Organization registry to describe the current practice of rest mechanical ventilation setting in children receiving veno-venous extracorporeal membrane oxygenation (V-V ECMO) and to determine if relationships exist between ventilator settings and mortality.

METHODS

Data for patients 14 days to 18 years old who received V-V ECMO from 2012-2016 were reviewed. Mechanical ventilation data available includes mode and settings at 24 h after ECMO cannulation. Multivariable logistic regression analysis was performed to determine if rest settings were associated with mortality.

RESULTS

We reviewed 1161 subjects, of which 1022 (88%) received conventional mechanical ventilation on ECMO. Rest settings, expressed as medians (25th%, 75th%), are as follows: rate 12 breaths/minute (10, 17); peak inspiratory pressure (PIP) 22 cmH₂O (20,27); positive end expiratory pressure (PEEP) 10 cmH₂O (8, 10); and fraction of inspired oxygen (F_iO₂) 0.4 (0.37, 0.60). Survival to discharge was 68%. Higher ventilator F_iO₂ (odds ratio:1.13 per 0.1 increase, 95% confidence interval:1.04, 1.23), independent of arterial oxygen saturation, was associated with mortality.

CONCLUSIONS

Current rest ventilator management for children receiving V-V ECMO primarily relies on conventional mechanical ventilation with moderate amounts of PIP, PEEP, and FiO₂. Further study on the relationship between FiO₂ and mortality should be pursued.

Impact of CRRT in Patients with PARDS Treated with VV-ECMO

The high mortality of pediatric acute respiratory distress syndrome (PARDS) is partly related to fluid overload. Extracorporeal membrane oxygenation (ECMO) is used to treat pediatric patients with severe PARDS, but can result in acute kidney injury (AKI) and worsening fluid overload. The objective of this study was to determine whether the addition of CRRT to ECMO in patients with PARDS is associated with increased mortality. Methods: We conducted a retrospective 7-year study of patients with PARDS requiring ECMO and divided them into those requiring CRRT and those not requiring CRRT. We calculated severity of illness scores, the amount of blood products administered to both groups, and determined the impact of CRRT on mortality and morbidity. Results: We found no significant difference in severity of illness scores except the vasoactive inotropic score (VIS, 45 ± 71 vs. 139 ± 251, p = 0.042), which was significantly elevated during the initiation and the first three days of ECMO. CRRT was associated with an increase in the use of blood products and noradrenaline (p < 0.01) without changing ECMO duration, length of PICU stay or mortality. Conclusion: The addition of CRRT to ECMO is associated with a greater consumption of blood products but no increase in mortality.

Direction and Magnitude of Change in Plateau From Peak Pressure During Inspiratory Holds Can Identify the Degree of Spontaneous Effort and Elastic Workload in Ventilated Patients

OBJECTIVES

Inspiratory holds with measures of airway pressure to estimate driving pressure (elastic work) are often limited to patients without respiratory effort. We sought to evaluate if measures of airway pressure during inspiratory holds could be used for patients with spontaneous respiratory effort during mechanical ventilation to estimate the degree of spontaneous effort and elastic work.

DESIGN

We compared the direction and degree of change in airway pressure during inspiratory holds versus esophageal pressure through secondary analysis of physiologic data.

SETTING

ICUs at Children's Hospital Los Angeles.

PATIENTS

Children with pediatric acute respiratory distress syndrome with evidence of spontaneous respiration while on pressure control or pressure support ventilation.

INTERVENTIONS

Inspiratory hold maneuvers.

MEASUREMENTS AND MAIN RESULTS

From airway pressure, we defined "plateau - peak pressure" as Pmusc, index, which was divided into three categories for analysis (< -1 ["negative"], between -1 and 1 ["neutral"], and > 1 cm H2O ["positive"]). A total of 30 children (age 36.8 mo [16.1-70.3 mo]) from 65 study days, comprising 118 inspiratory holds were included. Pmusc, index was "negative" in 29 cases, was "neutral" in 17 cases, and was "positive" in 72 cases. As Pmusc, index went from negative to neutral to positive, there was larger negative deflection in esophageal pressure -5.0 (-8.2 to 1.9), -5.9 (-7.6 to 4.3), and -10.7 (-18.1 to 7.9) cm H2O (p < 0.0001), respectively. There was a correlation between max negative esophageal pressure and Pmusc, index (r = -0.52), and when Pmusc, index was greater than or equal to 7 cm H2O, the max negative esophageal pressure was greater than 10 cm H2O. There was a stronger correlation between Pmusc, index and markers of elastic work from esophageal pressure (r = 0.84).

CONCLUSIONS

The magnitude of plateau minus peak pressure during an inspiratory hold is correlated with the degree of inspiratory effort, particularly for those with high elastic work. It may be useful to identify patients with excessively high effort or high driving pressure.

Longitudinal PEEP Responses Differ Between Children With ARDS and at Risk for ARDS

BACKGROUND

It is unknown whether lung mechanics differ between patients with pediatric ARDS and at risk for ARDS. We aimed to examine the hypothesis that, compared to ARDS, subjects at risk of ARDS are characterized by higher end-expiratory lung volume (EELV) or respiratory system compliance (C_RS) and lower distending pressure (stress) applied on the lung or parenchymal deformation (strain) during mechanical ventilation.

METHODS

Consecutively admitted subjects fulfilling the PALICC ARDS criteria were considered eligible for inclusion in this study. A ventilator with an integrated gas exchange module was used to calculate EELV, C_RS, strain, and stress after a steady state had been achieved based on nitrogen washout/washin technique. All subjects were subjected to incremental PEEP trials at 0, 6, 12, 24, 48, and 72 h.

RESULTS

A total of 896 measurements were longitudinally calculated in 32 mechanically ventilated subjects (n = 15 subjects with ARDS; n = 17 subjects at risk for ARDS). EELV correlated positively with strain or stress in the ARDS group (r = 0.30, P < .001) and the at risk group (r = 0.60, P < .001). C_RS correlated with strain (r = 0.40, P < .001) only in subjects at risk for ARDS. EELV increased over time as PEEP rose from 4 to 10 cm H₂O in subjects with ARDS (P = .001). In the at risk group, EELV only increased at 48 h (P = .001). Longitudinally, C_RS (P = .001) and EELV (P = .002) were lower and strain and stress were higher in subjects with ARDS compared to those at risk for ARDS (P = .002), remaining within safe limits. Strain and stress increased by 24 h but declined by 72 h in subjects with ARDS at a PEEP of 4 cm H₂O (P = .02). In the at risk group, strain and stress declined from 6 h to 72 h at a PEEP of 10 cm H₂O (P = .001).

CONCLUSIONS

Longitudinally, C_RS and EELV were lower and strain and stress were higher in subjects with ARDS compared to subjects at risk for ARDS. These parameters behaved differently over time at PEEP values of 4 or 10 cm H₂O. At these PEEP levels, strain and stress remained within safe limits in both groups.

Plasma Nucleosomes Are Associated With Mortality in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

Circulating nucleosomes and their component histones have been implicated as pathogenic in sepsis and acute respiratory distress syndrome in adults. However, their role in pediatric acute respiratory distress syndrome is unknown.

DESIGN

We performed a prospective cohort study in children with acute respiratory distress syndrome, with plasma collection within 24 hours of acute respiratory distress syndrome onset. We associated nucleosome levels with severity of acute respiratory distress syndrome and with nonpulmonary organ failures and tested for association of nucleosomes with PICU mortality and ventilator-free days at 28 days in univariate and multivariable analyses. We also performed proteomics of DNA-bound plasma proteins in a matched case-control study of septic children with and without acute respiratory distress syndrome in order to identify specific histone proteins elevated in acute respiratory distress syndrome.

SETTING

Large academic tertiary-care PICU.

PATIENTS

Intubated children meeting Berlin criteria for acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We enrolled 333 children with acute respiratory distress syndrome, with 69 nonsurvivors (21%). Plasma nucleosomes were correlated with acute respiratory distress syndrome severity and with the number of nonpulmonary organ failures at acute respiratory distress syndrome onset. Nucleosomes were higher (p < 0.001) in nonsurvivors (0.40 [interquartile range, 0.20-0.71] arbitrary units) relative to survivors (0.10 [interquartile range, 0.04-0.25] arbitrary units). Nucleosomes were associated with PICU mortality in multivariable analysis (adjusted odds ratio 1.84 per 1 sd increase; 95% CI, 1.38-2.45; p < 0.001). Nucleosomes were also associated with a lower probability of being extubated alive by day 28 after multivariable adjustment (adjusted subdistribution hazard ratio, 0.74; 95% CI, 0.63-0.88; p = 0.001). Proteomic analysis demonstrated higher levels of the core nucleosome histones H2A, H2B, H3, and H4 in septic children with acute respiratory distress syndrome, relative to septic children without acute respiratory distress syndrome.

CONCLUSIONS

Plasma nucleosomes are associated with acute respiratory distress syndrome severity, nonpulmonary organ failures, and worse outcomes in pediatric acute respiratory distress syndrome.

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.

Why COVID-19 is less frequent and severe in children: a narrative review

BACKGROUND

Despite the streaks of severity, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection is, in general, less frequent and severe in children than in adults. We searched for causal evidence of this mystery.

DATA SOURCES

An extensive search strategy was designed to identify papers on coronavirus disease 2019 (COVID-19). We searched Ovid MEDLINE, PubMed, EMBASE databases, and Cochrane library and carried out a review on the causes of this dilemma.

RESULTS

Our searches produced 81 relevant articles. The review showed that children accounted for a lower percentage of reported cases, and they also experienced less severe illness courses. Some potential explanations, including the tendency to engage the upper airway, the different expression in both receptors of angiotensin-converting enzyme and renin-angiotensin system, a less vigorous immune response, the lower levels of interleukin (IL)-6, IL-10, myeloperoxidase, and P-selectin and a higher intracellular adhesion molecule-1, a potential protective role of lymphocytes, and also lung infiltrations might have protective roles in the immune system-respiratory tract interactions. Finally, what have shed light on this under representation comes from two studies that revealed high-titer immunoglobulin-G antibodies against respiratory syncytial virus and mycoplasma pneumonia, may carry out cross-protection against SARS-CoV-2 infection, just like what suggested about the vaccines.

CONCLUSIONS

These results require an in-depth look. Properties of the immune system including a less vigorous adaptive system beside a preliminary potent innate response and a trained immunity alongside a healthier respiratory system, and their interactions, might protect children against SARS-CoV-2 infection. However, further studies are needed to explore other possible causes of this enigma.

High-Frequency Jet Ventilation in Pediatric Acute Respiratory Failure

BACKGROUND

High-frequency jet ventilation (HFJV) is primarily used in premature neonates; however, its use in pediatric patients with acute respiratory failure has been reported. The objective of this study was to evaluate HFJV use in the pediatric critical care setting. We hypothesized that HFJV would be associated with improvements in oxygenation and ventilation.

METHODS

Medical records of all patients who received HFJV in the pediatric ICU of a quaternary care center between 2014 and 2018 were retrospectively reviewed. Premature infants who had not been discharged home were excluded, as were those in whom HFJV was started while on extracorporeal membrane oxygenation. Data on demographics, pulmonary mechanics, gas exchange, and outcomes were extracted and analyzed using chi-square testing for categorical variables, nonparametric testing for continuous variables, and a linear effects model to evaluate gas exchange over time.

RESULTS

A total of 35 subjects (median age = 2.9 months, median weight = 5.2 kg) were included. Prior to HFJV initiation, median (interquartile range) oxygenation index (OI) was 11.3 (7.2-16.9), [Formula: see text] = 133 (91.3-190.0), pH = 7.18 (7.11-7.27), [Formula: see text] = 64 (52-87) mm Hg, and [Formula: see text] = 74 (64-125) mm Hg. For subjects still on HFJV (n = 25), there was no significant change in OI, [Formula: see text], or [Formula: see text] at 4-6 h after initiation, whereas pH increased (P = .001) and [Formula: see text] decreased (P = .001). For those remaining on HFJV for > 72 h (n = 12), the linear effects model revealed no differences over 72 h for OI, [Formula: see text], [Formula: see text], or mean airway pressure, but there was a decrease in [Formula: see text] while pH and [Formula: see text] increased. There were 9 (26%) subjects who did not survive, and nonsurvivors had higher Pediatric Index of Mortality 2 scores (P = .01), were more likely to be immunocompromised (P = .01), were less likely to have a documented infection (P = .02), and had lower airway resistance (P = .02).

CONCLUSIONS

HFJV was associated with improved ventilation among subjects able to remain on HFJV but had no significant effect on oxygenation.

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.

HFOV vs CMV for neonates with moderate-to-severe perinatal onset acute respiratory distress syndrome (NARDS): a propensity score analysis

This study aimed to evaluate whether high-frequency oscillatory ventilation (HFOV) could reduce mortality and the incidence of bronchopulmonary dysplasia (BPD) of perinatal-onset neonatal acute respiratory distress syndrome (NARDS) compared with conventional mechanical ventilation (CMV). Medical records were collected and retrospectively analyzed. Among the 700 neonates with NARDS who needed invasive ventilation, 501 (71.6%) received CMV, while 199 (28.4%) received HFOV. One-to-one propensity score matching (127:127) was used to match the baseline characteristics of patients who received CMV and HFOV. The results showed that birth weight and oxygenation index (OI) were independently associated with mortality in the multivariate logistic regression. No significant differences were observed in mortality or the incidence of BPD between the two groups. The incidence of intraventricular hemorrhage (IVH) and ventilation-free days were significantly lower in the HFOV group than in the CMV group (3.9 vs 11.80%, p=0.02; 15.226 vs 20.967 days, p=0.01). There were no significant differences between the two groups regarding other secondary outcomes.Conclusion: HFOV was associated with a decreased incidence of IVH in infants with NARDS compared with CMV. However, there were significantly more VFDs in the CMV group than in the HFOV group, and HFOV did not appear to be superior to CMV in decreasing the mortality and incidence of BPD in infants with NARDS. What is Known: • The diagnostic criteria of neonatal acute respiratory distress syndrome (Montreux criteria) were established in 2017. • To date, studies comparing high-frequency oscillatory ventilation and conventional mechanical ventilation in the treatment of neonatal acute respiratory distress syndrome are insufficient. What is New: • High-frequency oscillatory ventilation did not appear to be superior to conventional mechanical ventilation in decreasing the mortality and incidence of bronchopulmonary dysplasia in infants with moderate-to-severe perinatal-onset neonatal acute respiratory distress syndrome. • High-frequency oscillatory ventilation was associated with a decreased incidence of intraventricular hemorrhage in infants with moderate-to-severe perinatal-onset acute respiratory distress syndrome compared with conventional mechanical ventilation.

Management of Pediatric Septic Shock and Acute Respiratory Distress Syndrome in Thailand: A Survey of Pediatricians

Introduction: Pediatric septic shock and acute respiratory distress syndrome (pARDS) are major causes of morbidity and mortality in pediatric intensive care units (PICUs). While standardized guidelines for sepsis and pARDS are published regularly, their implementation and adherence to guidelines are different in resource-rich and resource-limited countries. The purpose of this study was to conduct a survey to ascertain variation in current clinician-reported practice in pediatric septic shock and acute respiratory distress syndrome, and the clinician skills in a variety of hospital settings throughout Thailand. Methods: We conducted an electronic survey in pediatricians throughout the country between August 2020 and February 2021 using multiple choice questions and clinical case scenarios based on the 2017 American College of Critical Care Medicine's Consensus guideline for pediatric and neonatal septic shock and the 2015 Pediatric Acute Lung Injury Consensus Conference. Results: The survey elicited responses from 255 pediatricians (125 general pediatricians, 38 pulmonologists, 27 cardiologists, 32 intensivists, and 33 other subspecialists), with 54.5% of the respondents having <5 years of PICU experience. Among the six sepsis scenarios, 72.5 and 78.4% of the respondents had good adherence to the guidelines for managing fluid refractory shock and sedation for intubation, respectively. The ICU physicians reported greater adherence during more complex shock. In ARDS scenarios, 80.8% of the respondents reported having difficulty diagnosing ARDS mimic conditions and used lesser PEEP than the recommendation. Acceptance of permissive hypercapnia and mild hypoxemia was accepted by 62.4 and 49.4% of respondents, respectively. The ICU physicians preferred decremental PEEP titration, whereas general pediatricians preferred incremental PEEP titration. Conclusion: This survey variation could be the result of resource constraints, knowledge gaps, or ambiguous guidelines. Understanding the perspective and rationale for variation in pediatricians' practices is critical for successful guideline implementation.

Diagnostic Accuracy of Plasma Ghrelin Concentrations in Pediatric Sepsis-Associated Acute Respiratory Distress Syndrome: A Single-Center Cohort Study

Background: Ghrelin is the endogenous ligand of growth hormone secretagogue receptor 1a, which plays a role in regulating immunity and inflammation. The aim of this study is to assess the diagnostic value of plasma ghrelin in sepsis-associated pediatric acute respiratory distress syndrome (PARDS). Methods: We recruited patients who were admitted to the pediatric ICU (PICU) of the Children's Hospital of Chongqing Medical University between January 2019 and January 2020 and met the diagnostic criteria for sepsis. Data on clinical variables, laboratory indicators, plasma ghrelin concentrations, and inflammatory factors were collected and evaluated, and patients were followed up for 28 days. The area under the receiver-operating characteristic curves (AUROC) were determined using logistic regression to calculate and test cut-off values for ghrelin as a diagnostic indicator of sepsis-associated PARDS. The log-rank test was used to compare survival according to ghrelin levels. Main results: Sixty-six PICU patients (30 with ARDS and 36 without ARDS) who met the diagnostic criteria of sepsis were recruited. The ghrelin level was significantly higher in the ARDS group than in the non-ARDS group. The AUROC of ghrelin was 0.708 (95% confidence interval: 0.584-0.833) and the positivity cutoff value was 445 pg/mL. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of plasma ghrelin for the diagnosis of PARDS-associated sepsis were 86.7, 50.0, 59.1, 81.8, 1.734, and 0.266%, respectively. The survival rate of sepsis patients were significantly improved when the ghrelin level was >445 pg/mL. Conclusions: Ghrelin plasma levels were higher in sepsis-associated PARDS, and accompanied by increased levels of inflammatory factors. High ghrelin levels are a positive predictor of ICU survival in sepsis patients. Yet, there is no evidence to prove that elevated ghrelin is a promising diagnostic indicator of sepsis-associated PARDS. Trial registration: Clinicaltrials, ChiCTR1900023254. Registered 1 December 2018 - Retrospectively registered, http://www.clinicaltrials.gov/ChiCTR1900023254.

Natural product derived phytochemicals in managing acute lung injury by multiple mechanisms

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) as common life-threatening lung diseases with high mortality rates are mostly associated with acute and severe inflammation in lungs. With increasing in-depth studies of ALI/ARDS, significant breakthroughs have been made, however, there are still no effective pharmacological therapies for treatment of ALI/ARDS. Especially, the novel coronavirus pneumonia (COVID-19) is ravaging the globe, and causes severe respiratory distress syndrome. Therefore, developing new drugs for therapy of ALI/ARDS is in great demand, which might also be helpful for treatment of COVID-19. Natural compounds have always inspired drug development, and numerous natural products have shown potential therapeutic effects on ALI/ARDS. Therefore, this review focuses on the potential therapeutic effects of natural compounds on ALI and the underlying mechanisms. Overall, the review discusses 159 compounds and summarizes more than 400 references to present the protective effects of natural compounds against ALI and the underlying mechanism.

Global PARITY: Study Design for a Multi-Centered, International Point Prevalence Study to Estimate the Burden of Pediatric Acute Critical Illness in Resource-Limited Settings

BACKGROUND

The burden of pediatric critical illness and resource utilization by children with critical illness in resource limited settings (RLS) are largely unknown. Without specific data that captures key aspects of critical illness, disease presentation, and resource utilization for pediatric populations in RLS, development of a contextual framework for appropriate, evidence-based interventions to guide allocation of limited but available resources is challenging. We present this methods paper which describes our efforts to determine the prevalence, etiology, hospital outcomes, and resource utilization associated with pediatric acute, critical illness in RLS globally.

METHODS

We will conduct a prospective, observational, multicenter, multinational point prevalence study in sixty-one participating RLS hospitals from North, Central and South America, Africa, Middle East and South Asia with four sampling time points over a 12-month period. Children aged 29 days to 14 years evaluated for acute illness or injury in an emergency department) or directly admitted to an inpatient unit will be enrolled and followed for hospital outcomes and resource utilization for the first seven days of hospitalization. The primary outcome will be prevalence of acute critical illness, which Global PARITY has defined as death within 48 hours of presentation to the hospital, including ED mortality; or admission/transfer to an HDU or ICU; or transfer to another institution for a higher level-of-care; or receiving critical care-level interventions (vasopressor infusion, invasive mechanical ventilation, non-invasive mechanical ventilation) regardless of location in the hospital, among children presenting to the hospital. Secondary outcomes include etiology of critical illness, in-hospital mortality, cause of death, resource utilization, length of hospital stay, and change in neurocognitive status. Data will be managed via REDCap, aggregated, and analyzed across sites.

DISCUSSION

This study is expected to address the current gap in understanding of the burden, etiology, resource utilization and outcomes associated with pediatric acute and critical illness in RLS. These data are crucial to inform future research and clinical management decisions and to improve global pediatric hospital outcomes.

Acute viral bronchiolitis as a cause of pediatric acute respiratory distress syndrome

The Pediatric Acute Lung Injury Consensus Conference (PALICC) published pediatric-specific guidelines for the definition, management, and research in pediatric acute respiratory distress syndrome (PARDS). Acute viral bronchiolitis (AVB) remains one of the leading causes of admission to PICU. Respiratory syncytial virus (RSV) is the most common cause of AVB. We aimed to evaluate the incidence of PARDS in AVB and identify the risk of RSV as a trigger pathogen for PARDS. This study is a retrospective single-center observational cohort study including children < 2 years of age admitted to the pediatric intensive care unit at St Mary's Hospital, London, and presented with AVB in 3 years (2016-2018). Clinical and demographic data was collected; PALICC criteria were applied to define PARDS. Data was expressed as median (IQR range); non-parametric tests were used. In this study, 144 infants with acute viral bronchiolitis were admitted to PICU in the study period. Thirty-nine infants fulfilled criteria of PARDS with RSV as the most common virus identified. Bacterial infection was identified as a risk factor for development of PARDS in infants with AVB.Conclusion: AVB is an important cause of PARDS in infants. RSV is associated with a higher risk of PARDS in AVB. Bacterial co-infection is a significant risk factor for development of PARDS in AVB. What is Known: • Bronchiolitis is a common cause of respiratory failure in children under 2 years. • ARDS is a common cause of PICU admission. What is New: • Evaluation of bronchiolitis as a cause of PARDS according to the PALLIC criteria. • Evaluation of different viruses' outcome in PARDS especially RSV as a commonest cause of AVB.

ATS Core Curriculum 2020. Pediatric Pulmonary Medicine

The American Thoracic Society Core Curriculum updates clinicians annually in adult and pediatric pulmonary disease, medical critical care, and sleep medicine, in a 3- to 4-year recurring cycle of topics. These topics will be presented at the 2020 International Conference. Below is the pediatric pulmonary medicine core, including pediatric hypoxemic respiratory failure; modalities in noninvasive management of chronic respiratory failure in childhood; surgical and nonsurgical management of congenital lung malformations; an update on smoke inhalation lung injury; an update on vaporizers, e-cigarettes, and other electronic delivery systems; pulmonary complications of sarcoidosis; pulmonary complications of congenital heart disease; and updates on the management of congenital diaphragmatic hernia.

The Use of a Kinetic Therapy Rotational Bed in Pediatric Acute Respiratory Distress Syndrome: A Case Series

Patients with acute respiratory distress syndrome (ARDS) commonly have dependent atelectasis and heterogeneous lung disease. Due to the heterogenous lung volumes seen, the application of positive end expiratory pressure (PEEP) can have both beneficial and deleterious effects. Alternating supine and prone positioning may be beneficial in ARDS by providing more homogenous distribution of PEEP and decreasing intrapulmonary shunt. In pediatrics, the pediatric acute lung injury and consensus conference (PALICC) recommended to consider it in severe pediatric ARDS (PARDS). Manually prone positioning patients can be burdensome in larger patients. In adults, the use of rotational beds has eased care of these patients. There is little published data about rotational bed therapy in children. Therefore, we sought to describe the use of a rotational bed in children with PARDS. We performed a retrospective case series of children who utilized a rotational bed as an adjunctive therapy for their PARDS. Patient data were collected and analyzed. Descriptive statistical analyses were performed and reported. Oxygenation indices (OI) pre- and post-prone positioning were analyzed. Twelve patients with PARDS were treated with a rotational bed with minimal adverse events. There were no complications noted. Three patients had malfunctioning of their arterial line while on the rotational bed. Oxygenation indices improved over time in 11 of the 12 patients included in the study while on the rotational bed. Rotational beds can be safely utilized in pediatric patients. In larger children with PARDS, where it may be more difficult to perform a manual prone position, use of a rotational bed can be considered a safe alternative.

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.

Endothelial Biomarkers Are Associated With Indirect Lung Injury in Sepsis-Associated Pediatric Acute Respiratory Distress Syndrome

Supplemental Digital Content is available in the text.

Objectives:

Acute respiratory distress syndrome occurring in the setting of direct versus indirect lung injury may reflect different pathobiologies amenable to different treatment strategies. We sought to test whether a panel of plasma biomarkers differed between children with sepsis-associated direct versus indirect acute respiratory distress syndrome. We hypothesized that a biomarker profile indicative of endothelial activation would be associated with indirect acute respiratory distress syndrome.

Design:

Observational cohort.

Setting:

Academic PICU.

Subjects:

Patients less than 18 years old with sepsis-associated direct (pneumonia, n = 52) or indirect (extrapulmonary sepsis, n = 46) acute respiratory distress syndrome.

Interventions:

None.

Measurements and Main Results:

Of 58 biomarkers examined, 33 differed by acute respiratory distress syndrome subtype. We used classification and regression tree methodology to examine associations between clinical and biochemical markers and acute respiratory distress syndrome subtype. The classification and regression tree model using only clinical variables (age, sex, race, oncologic comorbidity, and Pediatric Risk of Mortality-III score) performed worse than the classification and regression tree model using five clinical variables and 58 biomarkers. The best classification and regression tree model used only four endothelial biomarkers, including elevated angiopoietin-2/angiopoietin-1 ratio, vascular cell-adhesion molecule, and von Willebrand factor, to identify indirect acute respiratory distress syndrome. Test characteristics were 89% (80–97%) sensitivity, 80% (69–92%) specificity, positive predictive value 84% (74–93%), and negative predictive value 86% (76–96%).

Conclusions:

Indirect lung injury in children with acute respiratory distress syndrome is characterized by a biomarker profile indicative of endothelial activation, excess inflammation, and worse outcomes. A model using four biomarkers has the potential to be useful for more precisely identifying patients with acute respiratory distress syndrome whose pathobiology may respond to endothelial-targeted therapies in future trials.

Transfusion in the mechanically ventilated patient

Red blood cell transfusions are a frequent intervention in critically ill patients, including in those who are receiving mechanical ventilation. Both these interventions can impact negatively on lung function with risks of transfusion-related acute lung injury (TRALI) and other forms of acute respiratory distress syndrome (ARDS). The interactions between transfusion, mechanical ventilation, TRALI and ARDS are complex and other patient-related (e.g., presence of sepsis or shock, disease severity, and hypervolemia) or blood product-related (e.g., presence of antibodies or biologically active mediators) factors also play a role. We propose several strategies targeted at these factors that may help limit the risks of associated lung injury in critically ill patients being considered for transfusion.

[A school-aged boy with nephrotic syndrome with cough for one month and shortness of breath for half a month]

A boy, aged 6 years and 11 months, was admitted due to nephrotic syndrome for 2 years, cough for 1 month, and shortness of breath for 15 days. The boy had a history of treatment with hormone and immunosuppressant. Chest CT after the onset of cough and shortness of breath showed diffuse ground-glass opacities in both lungs. Serum (1, 3)-beta-D glucan was tested positive, and the nucleic acid of cytomegalovirus was detected in respiratory secretions. After the anti-fungal and anti-viral treatment, the child improved temporarily but worsened again within a short period of time. Pneumocystis jirovecii was identified by Gomori's methenamine silver staining in bronchoalveolar lavage fluid. The child was diagnosed with severe pneumonia (Pneumocystis jirovecii and cytomegalovirus infection), acute respiratory distress syndrome, and nephrotic syndrome. After anti-infective therapy with sulfamethoxazole/trimethoprim and ganciclovir and respiratory support, the child still experienced progressive aggravation of dyspnea and tension pneumothorax, and extracorporeal membrane oxygenation (ECMO) was given on day 13 of invasive ventilation. Anti-infective therapy with sulfamethoxazole/trimethoprim, ganciclovir, and linezolid, anticoagulation therapy, sedation therapy, nutrition, and comprehensive management of the respiratory tract were given during ECMO. The child was successfully weaned from ECMO after 72 days, resulting in a length of hospital stay of 134 days. The child was followed up for 6 months after discharge, and there was a significant improvement on lung CT, without organ dysfunction. It is concluded that Pneumocystis jirovecii pneumonia is a potential lifethreatening infection for children with low immunity, and that ECMO can effectively improve the prognosis of children with severe respiratory distress syndrome.

The role of computer-based clinical decision support systems to deliver protective mechanical ventilation

PURPOSE OF REVIEW

Mechanical ventilation of adults and children with acute respiratory failure necessitates balancing lung and diaphragm protective ventilation. Computerized decision support (CDS) offers advantages in circumstances where complex decisions need to be made to weigh potentially competing risks, depending on the physiologic state of the patient.

RECENT FINDINGS

Significant variability in how ventilator protocols are applied still exists and clinical data show that there continues to be wide variability in ventilator management. We have developed a CDS, which we are currently testing in a Phase II randomized controlled trial. The CDS is called Real-time Effort Driven ventilator management (REDvent). We will describe the rationale and methods for development of CDS for lung and diaphragm protective ventilation, using the REDvent CDS as an exemplar.

SUMMARY

Goals for achieving compliance and physiologic objectives can be met when CDS instructions are simple and explicit, provide the clinician with the underlying rule set, permit acceptable reasons for declining and allow for iterative adjustments.

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.

Undernutrition as an Aggravating Risk for Hospital Death in Critically Ill Children with Cancer

OBJECTIVES

Undernourished children with cancer are at major risk for adverse outcomes. We intended to model nutritional status as risk factor for hospital death.

METHODS

Retrospective analysis of two cohorts of children admitted in an oncology/hematology intensive care unit. Logistic regression was used for model building.

RESULTS

The derivation cohort had 155 patients, with a median age of 104.9 mo., and 36 deaths (23.2%). Twenty-eight children (18.1%) had the z score of the body mass index < -2. A multivariate model with the variables "relapse of oncological disease" (Odds Ratio 3.14, P = 0.025), "surgical case" (OR 0.22, P = 0.002), "intubation/mechanical ventilation" (OR 8.38, P = 0.000) and "body mass index z score < -2" (OR 3.21, P = 0.024) generated a logit with good predictive capacity for "hospital death". In the validation cohort, with 450 patients (median age of 92.7 mo.), the model was able to predict 55.5 of the 58 observed deaths (Standardized Mortality Rate = 1.04, 95% CI 0.80-1.34, P = 0.72), with P = 0.68 in the Hosmer test. The AUC was 0.90 (95% CI 0.86-0.93).

CONCLUSION

Undernutrition increases the risk of death, and is a variable that should be included in predictive mortality algorithms.

Acute Lung Injury: Disease Modelling and the Therapeutic Potential of Stem Cells

Acute lung injury (ALI) is a severe clinical condition with high morbidity and mortality that usually results in the development of multiple organ dysfunction. The complex pathophysiology of ALI seems to provide a wide range of targets that offer numerous therapeutic options. However, despite extensive studies of ALI pathophysiology and treatment, no effective pharmacotherapy is available. Increasing evidence from both preclinical and clinical studies supports the preventive and therapeutic effects of mesenchymal stem cells (MSCs) for treating ALI. As cell-based therapy poses the risk of occlusion in microvasculature or unregulated growth, MSC-derived extracellular vesicles (MSC-EVs) have been extensively studied as a new therapeutic strategy for non-cell based therapy. It is widely accepted that the therapeutic properties of MSCs are derived from soluble factors with paracrine or endocrine effects, and EVs are among the most important paracrine or endocrine vehicles that can deliver various soluble factors with a similar phenotype as the parent cell. Therapeutic effects of MSCs have been reported for various delivery approaches, diverse doses, multiple origins, and different times of administration, and MSC-EVs treatment may include but is not limited to these choices. The mechanisms by which MSCs and MSC-EVs may contribute to ALI treatment remain elusive and need further exploration. This review provides an overview of preclinical studies that support the application of MSC-EVs for treating ALI, and it discusses emerging opportunities and their associated challenges.

Differential type I interferon response and primary airway neutrophil extracellular trap release in children with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a heterogeneous condition characterized by the recruitment of large numbers of neutrophils into the lungs. Neutrophils isolated from the blood of adults with ARDS have elevated expression of interferon (IFN) stimulated genes (ISGs) associated with decreased capacity of neutrophils to kill Staphylococcus aureus and worse clinical outcomes. Neutrophil extracellular traps (NETs) are elevated in adults with ARDS. Whether pediatric ARDS (PARDS) is similarly associated with altered neutrophil expression of ISGs and neutrophil extracellular trap release is not known. Tracheal aspirate fluid and cells were collected within 72 h from seventy-seven intubated children. Primary airway neutrophils were analyzed for differential ISG expression by PCR, STAT1 phosphorylation and markers of degranulation and activation by flow cytometry. Airway fluid was analyzed for the release of NETs by myeloperoxidase-DNA complexes using an ELISA. Higher STAT1 phosphorylation, markers of neutrophil degranulation, activation and NET release were found in children with versus without PARDS. Higher NETs were detected in the airways of children with ventilator-free days less than 20 days. Increased airway cell IFN signaling, neutrophil activation, and NET production is associated with PARDS. Higher levels of airway NETs are associated with fewer ventilator-free days.

Clinical Manifestations and Outcomes of Critically Ill Children and Adolescents with Coronavirus Disease 2019 in New York City

OBJECTIVES

To describe the clinical manifestations and outcomes of critically ill children with coronavirus disease-19 (COVID-19) in New York City.

STUDY DESIGN

Retrospective observational study of children 1 month to 21 years admitted March 14 to May 2, 2020, to 9 New York City pediatric intensive care units (PICUs) with severe acute respiratory syndrome coronavirus 2 infection.

RESULTS

Of 70 children admitted to PICUs, median age was 15 (IQR 9, 19) years; 61.4% male; 38.6% Hispanic; 32.9% black; and 74.3% with comorbidities. Fever (72.9%) and cough (71.4%) were the common presenting symptoms. Twelve patients (17%) met severe sepsis criteria; 14 (20%) required vasopressor support; 21 (30%) developed acute respiratory distress syndrome (ARDS); 9 (12.9%) met acute kidney injury criteria; 1 (1.4%) required renal-replacement therapy, and 2 (2.8%) had cardiac arrest. For treatment, 27 (38.6%) patients received hydroxychloroquine; 13 (18.6%) remdesivir; 23 (32.9%) corticosteroids; 3 (4.3%) tocilizumab; and 1 (1.4%) anakinra; no patient was given immunoglobulin or convalescent plasma. Forty-nine (70%) patients required respiratory support: 14 (20.0%) noninvasive mechanical ventilation, 20 (28.6%) invasive mechanical ventilation (IMV), 7 (10%) prone position, 2 (2.8%) inhaled nitric oxide, and 1 (1.4%) extracorporeal membrane oxygenation. Nine (45%) of the 20 patients requiring IMV were extubated by day 14 with median IMV duration of 218 (IQR 79, 310.4) hours. Presence of ARDS was significantly associated with duration of PICU and hospital stay, and lower probability of PICU and hospital discharge at hospital day 14 (P < .05 for all).

CONCLUSIONS

Critically ill children with COVID-19 predominantly are adolescents, have comorbidities, and require some form of respiratory support. The presence of ARDS is significantly associated with prolonged PICU and hospital stay.

Real-Time Effort Driven Ventilator Management: A Pilot Study

OBJECTIVES

Mechanical ventilation of patients with acute respiratory distress syndrome should balance lung and diaphragm protective principles, which may be difficult to achieve in routine clinical practice. Through a Phase I clinical trial, we sought to determine whether a computerized decision support-based protocol (real-time effort-driven ventilator management) is feasible to implement, results in improved acceptance for lung and diaphragm protective ventilation, and improves clinical outcomes over historical controls.

DESIGN

Interventional nonblinded pilot study.

SETTING

PICU.

PATIENTS

Mechanically ventilated children with acute respiratory distress syndrome.

INTERVENTIONS

A computerized decision support tool was tested which prioritized lung-protective management of peak inspiratory pressure-positive end-expiratory pressure, positive end-expiratory pressure/FIO2, and ventilatory rate. Esophageal manometry was used to maintain patient effort in a physiologic range. Protocol acceptance was reported, and enrolled patients were matched 4:1 with respect to age, initial oxygenation index, and percentage of immune compromise to historical control patients for outcome analysis.

MEASUREMENTS AND MAIN RESULTS

Thirty-two patients were included. Acceptance of protocol recommendations was over 75%. One-hundred twenty-eight matched historical controls were used for analysis. Compared with historical controls, patients treated with real-time effort-driven ventilator management received lower peak inspiratory pressure-positive end-expiratory pressure and tidal volume, and higher positive end-expiratory pressure when FIO2 was greater than 0.60. Real-time effort-driven ventilator management was associated with 6 more ventilator-free days, shorter duration until the first spontaneous breathing trial and 3 fewer days on mechanical ventilation among survivors (all p ≤ 0.05) in comparison with historical controls, while maintaining no difference in the rate of reintubation.

CONCLUSIONS

A computerized decision support-based protocol prioritizing lung-protective ventilation balanced with reduction of controlled ventilation to maintain physiologic levels of patient effort can be implemented and may be associated with shorter duration of ventilation.

Clinician Accuracy in Identifying and Predicting Organ Dysfunction in Critically Ill Children

OBJECTIVES

To determine clinician accuracy in the identification and prediction of multiple organ dysfunction syndrome.

DESIGN

Prospective cohort study.

SETTING

University of Michigan's C.S. Mott Children's Hospital PICU.

PATIENTS

Patients admitted to the PICU with an anticipated PICU length of stay greater than 48 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

For each patient, the clinical team (attending, fellow, resident/nurse practitioner) was surveyed regarding existing and anticipated organ dysfunction. The primary outcomes were clinicians' accuracy at identifying multiple organ dysfunction syndrome and predicting new or progressive multiple organ dysfunction syndrome, compared to the objective assessment of multiple organ dysfunction syndrome using Proulx criteria. We also measured sensitivity, specificity, negative and positive predictive values, and negative and positive likelihood ratios of clinician assessments. We tested for differences in accuracy by clinician type using chi-square tests. Clinicians rated their confidence in prediction on a 5-point Likert scale. There were 476 eligible PICU admissions, for whom 1,218 surveys were completed. Multiple organ dysfunction syndrome was present in 89 patients (18.7%) at enrollment, and new or progressive multiple organ dysfunction syndrome occurred in 39 (8.2%). Clinicians correctly identified multiple organ dysfunction syndrome with 79.9% accuracy and predicted additional organ dysfunction with 82.6% accuracy. However, the positive and negative likelihood ratios for new or progressive multiple organ dysfunction syndrome prediction were 3.0 and 0.7, respectively, indicating a weak relationship between the clinician prediction and development of new or progressive multiple organ dysfunction syndrome. The positive predictive value of new or progressive multiple organ dysfunction syndrome prediction was just 22.1%. We found no differences in accuracy by clinician type for either identification of multiple organ dysfunction syndrome (80.2% vs 78.2% vs 81.0%; p = 0.57) or prediction of new or progressive multiple organ dysfunction syndrome (84.8% vs 82.8% vs 80.3%; p = 0.26) for attendings, fellows, and residents/nurse practitioners, respectively. There was a weak correlation between the confidence and accuracy of prediction (pairwise correlation coefficient, 0.26; p < 0.001).

CONCLUSIONS

PICU clinicians correctly identified multiple organ dysfunction syndrome and predicted new or progressive multiple organ dysfunction syndrome with 80% accuracy. However, only 8% of patients developed new or progressive multiple organ dysfunction syndrome, so accuracy was largely due to true negative predictions. The positive predictive value for new or progressive multiple organ dysfunction syndrome prediction was just 22%. Accuracy did not differ by clinician type, but was correlated with self-rated confidence and was higher for negative predictions.

Association of patient weight status with plasma surfactant protein D, a biomarker of alveolar epithelial injury, in children with acute respiratory failure

AIMS AND OBJECTIVES

Alveolar epithelial injury is a key determinant of acute respiratory failure (ARF) severity. Plasma surfactant protein D (SP-D), a biomarker of alveolar epithelial injury, is lower in obese adults with ARF compared to their lean peers. We aimed to determine if children with ARF have similar variance in plasma SP-D associated with their weight status on admission.

METHODS

Plasma SP-D was measured on days 0, 1, or 2 in children (1-18 years) with ARF enrolled in the genetic variation and biomarkers in children with acute lung injury and RESTORE studies. Weight classification (underweight, normal, overweight, and obese) was based on body mass index or weight-for-height z-scores. Associations between weight group and SP-D on each day were tested.

RESULTS

Inclusion criteria were met in 212 subjects, 24% were obese. There were no differences among weight groups in SP-D levels on days 0 and 1. However, on day 2, there was a statistically significant linear trend for lower SP-D levels as weight increased in both the univariate analysis (P = .02) and when adjusting for age, ethnicity, and diagnosis of pediatric acute respiratory distress syndrome (P = .05).

CONCLUSIONS

Obesity was associated with lower plasma SP-D levels on day 2 of ARF. This finding may be explained by altered ARF pathogenesis in obese individuals or a reduced incidence of ventilator-induced lung injury.