Mechanical power and normalized mechanical power in pediatric acute respiratory distress syndrome

Background

Mechanical power (MP) refers to the energy transmitted over time to the respiratory system and serves as a unifying determinant of ventilator-induced lung injury. MP normalization is required to account for developmental changes in children. We sought to examine the relationship between mechanical energy (MEBW), MP normalized to body weight (MPBW), and MP normalized to respiratory compliance (MPCRS) concerning the severity and outcomes of pediatric acute respiratory distress syndrome (pARDS).

Method

In this retrospective study, children aged 1 month to 18 years diagnosed with pARDS who underwent pressure-control ventilation for at least 24 h between January 2017 and September 2020 were enrolled. We calculated MP using Becher's equation. Multivariable logistic regression analysis adjusted for age, pediatric organ dysfunction score, and oxygenation index (OI) was performed to determine the independent association of MP and its derivatives 24 h after diagnosing pARDS with 28-day mortality. The association was also studied for 28 ventilator-free days (VFD-28) and the severity of pARDS in terms of OI.

Results

Out of 246 admitted with pARDS, 185 were eligible, with an overall mortality of 43.7%. Non-survivors exhibited higher severity of illness, as evidenced by higher values of MP, MPBW, and MEBW. Multivariable logistic regression analysis showed that only MEBW but not MP, MPBW, or MPCRS at 24 h was independently associated with mortality [adjusted OR: 1.072 (1.002-1.147), p = 0.044]. However, after adjusting for the type of pARDS, MEBW was not independently associated with mortality [adjusted OR: 1.061 (0.992-1.136), p = 0.085]. After adjusting for malnutrition, only MP at 24 h was found to be independently associated. Only MPCRS at 1-4 and 24 h but not MP, MPBW, or MEBW at 24 h of diagnosing pARDS was significantly correlated with VFD-28.

Conclusions

Normalization of MP is better related to outcomes and severity of pARDS than non-normalized MP. Malnutrition can be a significant confounding factor in resource-limited settings.

Case report: Miliary tuberculosis complicated by pediatric acute respiratory distress syndrome in a 12-year-old girl

Acute respiratory distress syndrome (ARDS) is a rare complication of miliary tuberculosis, particularly in pediatric patients. Comorbidities and delayed diagnosis can worsen the prognosis of patients with miliary tuberculosis. A 12-year-old girl presented with fever for 20 days, and cough and tachypnea for 4 days. She was diagnosed with miliary tuberculosis complicated by pediatric ARDS. She had atypical clinical manifestations and imaging findings, a negative contact history, and negative results of a tuberculin skin test (TST) and T-SPOT.TB. Diagnostic bronchoscopy and bronchoalveolar lavage helped make the diagnosis of tuberculosis. Effective treatment was promptly initiated after confirmation of the diagnosis, and the patient's condition improved. This case illustrates that a negative contact history and laboratory results cannot rule out tuberculosis. False-negative TST and T-SPOT.TB results should be evaluated carefully. Bronchoscopy may be useful for identifying pathogens in patients with pneumonia of unknown etiology, and corticosteroids should be administered with caution.

Predictors of Failure of Noninvasive Ventilation in Critically Ill Children

Noninvasive ventilation (NIV) is a common modality employed to treat acute respiratory failure. Most data guiding its use is extrapolated from adult studies. We sought to identify clinical predictors associated with failure of NIV, defined as requiring intubation. This single-center retrospective observational study included children admitted to pediatric intensive care unit (PICU) between July 2014 and June 2016 treated with NIV, excluding postextubation. A total of 148 patients was included. Twenty-seven (18%) failed NIV. There was no difference between the two groups with regard to age, gender, comorbidities, or etiology of acute respiratory failure. Those that failed had higher admission pediatric risk of mortality ( p  = 0.01) and pediatric logistic organ dysfunction ( p  = 0.002) scores and higher fraction of inspired oxygen (FiO 2 ; p  = 0.009) at NIV initiation. Failure was associated with lack of improvement in tachypnea. At 6 hours of NIV, the failure group had worsening tachypnea with a median increase in respiratory rate of 8%, while the success group had a median reduction of 18% ( p  = 0.06). Multivariable Cox's proportional hazard models revealed FiO 2 at initiation and worsening respiratory rate at 1- and 6-hour significant risks for failure of NIV. Failure was associated with a significantly longer PICU length of stay (success [2.8 days interquartile range (IQR): 1.7, 5.5] vs. failure [10.6 days IQR: 5.6, 13.2], p  < 0.001). NIV can be successfully employed to treat acute respiratory failure in pediatric patients. There should be heightened concern for NIV failure in hypoxemic patients whose tachypnea is unresponsive to NIV. A trend toward improvement should be closely monitored.

Mechanical Power Is Associated With Mortality in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

Mechanical power (MP) transferred from the ventilator to the lungs has been proposed as a summary variable that may impact mortality in children with acute respiratory distress syndrome (ARDS). To date, no study has shown an association between higher MP and mortality in children with ARDS.

DESIGN

Secondary analysis of a prospective observational study.

SETTING

Single-center, tertiary, academic PICU.

PATIENTS

Five hundred forty-six intubated children with ARDS enrolled between January 2013 and December 2019 receiving pressure-controlled ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Higher MP was associated with increased mortality (adjusted hazard ratio [HR] 1.34 per 1 sd increase, 95% CI 1.08-1.65; p = 0.007). When assessing the contribution of individual components of MP, only positive end-expiratory pressure (PEEP) was associated with mortality (HR 1.32; p = 0.007), whereas tidal volume, respiratory rate, and driving pressure (ΔP = [peak inspiratory pressure (PIP)-PEEP]) were not. Finally, we tested whether there remained an association when specific terms were removed from the MP equation by calculating MP from static strain (remove ΔP), MP from dynamic strain (remove PEEP), and mechanical energy (remove respiratory rate). MP from static strain (HR 1.44; p < 0.001), MP from dynamic strain (HR 1.25; p = 0.042), and mechanical energy (HR 1.29; p = 0.009) were all associated with mortality. MP was associated with ventilator-free days only when using MP normalized to predicted body weight, but not when using measured weight.

CONCLUSIONS

Higher MP was associated with mortality in pediatric ARDS, and PEEP appears to be the component most consistently driving this association. As higher PEEP is used in sicker patients, the association between MP and mortality may reflect a marker of illness severity rather than MP itself being causal for mortality. However, our results support future trials testing different levels of PEEP in children with ARDS as a potential means to improve outcome.

RNA Sequencing Analysis of CD4+ T Cells Exposed to Airway Fluid From Children With Pediatric Acute Respiratory Distress Syndrome

CD4⁺ T cells contribute to lung inflammation in acute respiratory distress syndrome. The CD4⁺ T-cell response in pediatric acute respiratory distress syndrome (PARDS) is unknown.

OBJECTIVES

To identify differentially expressed genes and networks using a novel transcriptomic reporter assay with donor CD4⁺ T cells exposed to the airway fluid of intubated children with mild versus severe PARDS.

DESIGN

In vitro pilot study.

SETTING

Laboratory-based study using human airway fluid samples admitted to a 36-bed university-affiliated pediatric intensive care unit.

PATIENTS/SUBJECTS

Seven children with severe PARDS, nine children with mild PARDS, and four intubated children without lung injury as controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We performed bulk RNA sequencing using a transcriptomic reporter assay of CD4⁺ T cells exposed to airway fluid from intubated children to discover gene networks differentiating severe from mild PARDS. We found that innate immunity pathways, type I (α and β), and type II (γ) interferon response and cytokine/chemokine signaling are downregulated in CD4⁺ T cells exposed to airway fluid from intubated children with severe PARDS compared with those with mild PARDS.

CONCLUSIONS

We identified gene networks important to the PARDS airway immune response using bulk RNA sequencing from a novel CD4⁺ T-cell reporter assay that exposed CD4⁺ T cells to airway fluid from intubated children with severe and mild PARDS. These pathways will help drive mechanistic investigations into PARDS. Validation of our findings using this transcriptomic reporter assay strategy is needed.

Fluid Overload Precedes and Masks Cryptic Kidney Injury in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

Given the complex interrelatedness of fluid overload (FO), creatinine, acute kidney injury (AKI), and clinical outcomes, the association of AKI with poor outcomes in critically ill children may be underestimated due to definitions used. We aimed to disentangle these temporal relationships in a large cohort of children with acute respiratory distress syndrome (ARDS).

DESIGN

Retrospective cohort study.

SETTING

Quaternary care PICU.

PATIENTS

Seven hundred twenty intubated children with ARDS between 2011 and 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Daily fluid balance, urine output (UOP), and creatinine for days 1-7 of ARDS were retrospectively abstracted. A subset of patients had angiopoietin 2 (ANGPT2) quantified on days 1, 3, and 7. Patients were classified as AKI by Kidney Disease Improving Global Outcomes (KDIGO) stage 2/3 then grouped by timing of AKI onset (early if days 1-3 of ARDS, late if days 4-7 of ARDS, persistent if both) for comparison of PICU mortality and ventilator-free days (VFDs). A final category of "Cryptic AKI" was used to identify subjects who met KDIGO stage 2/3 criteria only when creatinine was adjusted for FO. Outcomes were compared between those who had Cryptic AKI identified by FO-adjusted creatinine versus those who had no AKI. Conventionally defined AKI occurred in 26% of patients (early 10%, late 3%, persistent 13%). AKI was associated with higher mortality and fewer VFDs, with no differences according to timing of onset. The Cryptic AKI group (6% of those labeled no AKI) had higher mortality and fewer VFDs than patients who did not meet AKI with FO-adjusted creatinine. FO, FO-adjusted creatinine, and ANGPT2 increased 1 day prior to meeting AKI criteria in the late AKI group.

CONCLUSIONS

AKI was associated with higher mortality and fewer VFDs in pediatric ARDS, irrespective of timing. FO-adjusted creatinine captures a group of patients with Cryptic AKI with outcomes approaching those who meet AKI by traditional criteria. Increases in FO, FO-adjusted creatinine, and ANGPT2 occur prior to meeting conventional AKI criteria.

A Web-Based Platform for the Automatic Stratification of ARDS Severity

Acute respiratory distress syndrome (ARDS), including severe pulmonary COVID infection, is associated with a high mortality rate. It is crucial to detect ARDS early, as a late diagnosis may lead to serious complications in treatment. One of the challenges in ARDS diagnosis is chest X-ray (CXR) interpretation. ARDS causes diffuse infiltrates through the lungs that must be identified using chest radiography. In this paper, we present a web-based platform leveraging artificial intelligence (AI) to automatically assess pediatric ARDS (PARDS) using CXR images. Our system computes a severity score to identify and grade ARDS in CXR images. Moreover, the platform provides an image highlighting the lung fields, which can be utilized for prospective AI-based systems. A deep learning (DL) approach is employed to analyze the input data. A novel DL model, named Dense-Ynet, is trained using a CXR dataset in which clinical specialists previously labelled the two halves (upper and lower) of each lung. The assessment results show that our platform achieves a recall rate of 95.25% and a precision of 88.02%. The web platform, named PARDS-CxR, assigns severity scores to input CXR images that are compatible with current definitions of ARDS and PARDS. Once it has undergone external validation, PARDS-CxR will serve as an essential component in a clinical AI framework for diagnosing ARDS.

Methodology of the Second Pediatric Acute Lung Injury Consensus Conference

OBJECTIVES

This article describes the methodology used for The Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2). The PALLIC-2 sought to develop evidence-based clinical recommendations and when evidence was lacking, expert-based consensus statements and research priorities for the diagnosis and management of pediatric acute respiratory distress syndrome (PARDS).

DATA SOURCES

Electronic searches were conducted using PubMed, Embase, and Cochrane Library (CENTRAL) databases from 2012 to March 2022.

STUDY SELECTION

Content was divided into 11 sections related to PARDS, with abstract and full text screening followed by data extraction for studies which met inclusion with no exclusion criteria.

DATA EXTRACTION

We used a standardized data extraction form to construct evidence tables, grade the evidence, and formulate recommendations or statements using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

DATA SYNTHESIS

This consensus conference was comprised of a multidisciplinary group of international experts in pediatric critical care, pulmonology, respiratory care, and implementation science which followed standards set by the Institute of Medicine, using the GRADE system and Research And Development/University of California, Los Angeles appropriateness method, modeled after PALICC 2015. The panel of 52 content and four methodology experts had several web-based meetings over the course of 2 years. We conducted seven systematic reviews and four scoping reviews to cover the 11 topic areas. Dissemination was via primary publication listing all statements and separate supplemental publications for each subtopic that include supporting arguments for each recommendation and statement.

CONCLUSIONS

A consensus conference of experts from around the world developed recommendations and consensus statements for the definition and management of PARDS and identified evidence gaps which need further research.

Expression Patterns of Airway Fluid Cytokines From Intubated Children With Pediatric Acute Respiratory Distress Syndrome

Pediatric acute respiratory distress syndrome (PARDS) is a heterogeneous illness affecting 6% of mechanically ventilated children and with an overall mortality of 17%. Studies in PARDS have mainly focused on plasma biomarkers which may not reflect airway biomarkers. We lack adequate understanding of the inflammatory mediators and underlying immune responses in the airways of PARDS patients. Our objective was to compare the levels of cytokines in the airway fluid of intubated children with severe versus nonsevere acute respiratory distress syndrome.

DESIGN

Prospective observational cohort study.

SETTING

Single 36-bed quaternary care academic safety-net hospital PICU.

PATIENTS

Children intubated for acute respiratory failure between January 2018 and November 2021 stratified by Pediatric Acute Lung Injury Consensus Conference-1 criteria for PARDS.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured levels of 23 cytokines, chemokines, and protein biomarkers in the tracheal aspirate from 82 intubated children, between 14 days and 17 years old, at risk for or with PARDS. Levels of interleukin-4, -5, -7, -8, -12(p-70), -17a, -21, and fractalkine were higher in patients with severe versus nonsevere PARDS. There were no associations between airway and plasma cytokines.

CONCLUSIONS

Proinflammatory cytokines are elevated in the airway fluid from intubated children with severe PARDS and reflect diverse patterns of airway inflammation.

High Flow Nasal Cannula in the Pediatric Intensive Care Unit

INTRODUCTION

The use of high flow nasal cannula (HFNC) has become widely used in pediatric intensive care units (PICUs) throughout the world. The rapid adoption has outpaced the number of studies evaluating the safety and efficacy in a variety of pediatric diseases/conditions.

AREAS COVERED

This scoping review begins with the definition and mechanisms of action of HFNC and then follows with a review of the literature focused on studies performed on critically ill children cared for in the PICU. The Pubmed database was searched with a pediatric filter from the time period 2000 to 2021.

EXPERT OPINION

The rapid adoption of HFNC in PICUs has largely been driven by changes in institutional practices and small observational studies. There is a lack of adequately powered studies evaluating patient-centered outcomes, such as intubation rates, mortality, PICU and hospital length of stay. Given the wide variability in flow rates and clinical indications, more research is needed to better define effective flow rates for different disease states as well as markers of treatment success and failure. One particular entity that is poorly studied is the use of HFNC in those at risk for developing pediatric acute respiratory distress syndrome (PARDS).

Fluid overload in children with pediatric acute respiratory distress syndrome: A retrospective cohort study

OBJECTIVES

To assess the association of cumulative fluid overload (FO) up to 14 days from the diagnosis of pediatric acute respiratory syndrome (PARDS) with pediatric intensive care unit (PICU) mortality, 28-day mechanical ventilation free days (VFD), and 28-day intensive care unit free days (IFD). We hypothesized that fluid overload, even beyond the acute period, would be associated with increased morbidity and mortality.

METHODS

We conducted a retrospective cohort study of PARDS patients admitted to PICU from 2009 to 2015. For repeated admissions, we considered the admission with the highest oxygenation index (OI). Daily FO (%) was calculated as (intake - output)/weight at PICU admission × 100. Peak cumulative FO (CFO) was the highest CFO from the diagnosis of PARDS to Day 14 or to PICU discharge or mortality, whichever was earliest. Rate to peak CFO was the peak CFO divided by the number of days to reach that highest CFO. The association of FO with mortality, VFD and IFD were analyzed with logistic and linear regression models, with the following covariates: Pediatric Index of Mortality 2 score, PARDS severity, and the presence of acute kidney injury (AKI).

RESULTS

There were 165 patients included in this study, with a mortality rate of 45.5% (75/165), median age 3.2 years (interquartile range [IQR] 0.7-9.9) and OI 15.8 (IQR 9.5-27.9). Seventy-three (44.2%) patients had severe PARDS and 64 (38.8%) had AKI. AKI (aOR [adjusted odds ratio] 3.19, 95% CI [confidence interval] 1.43-7.09, p = 0.004) and rate to peak cumulative FO (aOR 1.23, 95% CI 1.07-1.42, p = 0.004) were associated with mortality. AKI and peak cumulative FO were associated with decreased VFD and IFD.

CONCLUSION

The rate to peak CFO over the first 14 days of PARDS was associated with mortality and peak CFO was associated with decreased VFD and IFD.

Correlation Between the Ratio of Oxygen Saturation to Fraction of Inspired Oxygen and the Ratio of Partial Pressure of Oxygen to Fraction of Inspired Oxygen in Detection and Risk Stratification of Pediatric Acute Respiratory Distress Syndrome

Objective: To measure the correlation between the ratio of oxygen saturation to fraction of inspired oxygen [SpO₂/FiO₂ (SF)] and the ratio of partial pressure of oxygen to fraction of inspired oxygen [PaO₂/FiO₂ (PF)] among children diagnosed with acute respiratory distress syndrome (ARDS).

Methodology: A cross-sectional study was conducted at the pediatric intensive care unit (PICU), National Institute of Child Health (NICH), Karachi, a tertiary care government hospital, from November 2020 to July 2021. One hundred twenty children (of either gender) having the age range of 2 months to 16 years, admitted to PICU with acute onset of respiratory distress, were included in the study. We measured SpO₂, PaO₂, FiO₂ and calculated SF and PF ratios. SPSS (version 23) (Armonk, NY: IBM Corp) was used to analyze data, and the Spearmen's correlation test was applied to measure the relationship between SF and PF ratios.

Results: A total of 120 children were included, the mean age was 40.58±38.88 months and 67 (55.8%) were males. The mean FiO₂ was 76.33%, the mean PaO₂ and SpO₂ were 100.35 mmHg and 94.37%, respectively. The mean PF ratio was 156.34, and the mean SF ratio was 156.45. There was a strong correlation between the SF ratio and the PF ratio (r=0.688; p=0.001).

Conclusion: This study has shown that there is a strong correlation between the SF and PF ratios, and a statistically substantial agreement has been observed.

Potential therapeutics in pediatric acute respiratory distress syndrome: what does the immune system have to offer? A narrative review

Since first described, acute respiratory distress syndrome (ARDS) has been understood to be an inflammatory disease with a dysregulated hyperinflammatory response. While fewer investigations have studied these phenomena in pediatric ARDS (PARDS), similar pathways are believed to be involved. Significant attention has been paid to the innate immune system, particularly neutrophils and neutrophil-related signaling, more recent studies have provided additional nuance regarding the role of upstream damage-associated molecular patterns (DAMPs) and subsequent neutrophil-mediated inflammation, lung permeability, and alveolar epithelial damage. For example, neutrophil extracellular traps (NETs) and inflammasome signaling have been identified as critical mediators existing at the junction of DAMPs and downstream inflammation. We demonstrate how the conclusions obtained from pre-clinical studies of lung injury are highly dependent upon the model chosen, and how this can lead us astray when developing therapies. More recently the adaptive immune system, specifically select T cell subpopulations, have also been implicated in ARDS. This raises the possibility of antigen-specific immunomodulation as a potential therapeutic avenue in ARDS. Finally, we briefly review randomized controlled trials attempting to manipulate the immune dysregulation in ARDS, including pleiotropic immunomodulators like corticosteroids and interferon-β, and what these studies can teach us about the design of novel therapeutics and the design of future trials.

Timing and Clinical Significance of Fluid Overload in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

Fluid overload is associated with worse outcomes in adult and pediatric acute respiratory distress syndrome. However, the time-course of fluid overload and its relationship to outcome has not been described. We aimed to determine the relationship between the timing of fluid overload and outcomes over the first 7 days after acute respiratory distress syndrome onset in children.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary care PICU.

PATIENTS

Intubated children with acute respiratory distress syndrome between 2011 and 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Daily and cumulative total fluid intake, total output, urine output, and fluid balance were collected for each 24-hour period from days 1 to 7 after acute respiratory distress syndrome onset. We tested the association between daily cumulative fluid metrics with PICU mortality and probability of extubation by 28 days using multivariable logistic and competing risk regression, respectively. In a subset of children, plasma was collected on day 1 and day 3 of acute respiratory distress syndrome and angiopoietin-2 quantified. Of 723 children with acute respiratory distress syndrome, 132 died (18%). In unadjusted analysis, nonsurvivors had higher cumulative fluid balance starting on day 3. In multivariable analysis, a positive cumulative fluid balance on days 5 through 7 was associated with increased mortality. Higher cumulative fluid balance on days 4 to 7 was associated with lower probability of extubation. Elevated angiopoietin-2 on day 1 predicted early (within 3 d) fluid overload greater than or equal to 10%, and elevated angiopoietin-2 on day 3 predicted late (between days 4 and 7) fluid overload.

CONCLUSIONS

Fluid overload after day 4 of acute respiratory distress syndrome, but not before, was associated with worse outcomes. Higher angiopoietin-2 predicted subsequent fluid overload. Our results suggest that future interventions aimed at managing fluid overload may have differential efficacy depending on when in the time-course of acute respiratory distress syndrome they are initiated.

Hemadsorption as rescue therapy for patients with multisystem organ failure in pediatric intensive care-Two case reports and review of the literature

Hemadsorption via the cytokine‐adsorber CytoSorb (CytoSorbents Europe, Berlin, Germany) has successfully been used as an adjunctive method in adults, mainly for the purpose of immunomodulation under acute inflammatory conditions such as sepsis and cardiac surgery. In recent years, there has been growing interest in its use in pediatric intensive care to improve outcomes in patients with multiple organ failure following an inflammatory illness. Literature on the application of CytoSorb in neonatal and pediatric patients is scarce, though the implication is that it could be an effective last‐resort treatment option in critically ill pediatric patients. Herein we present the clinical cases of two pediatric patients successfully treated with a combination of the CytoSorb hemadsorber, continuous renal replacement therapy, and extracorporeal membrane oxygenation due to multiple organ failure following different underlying medical conditions. Patient 1 was a 7‐month‐old male child with Down's syndrome admitted to the Pediatric Intensive Care Unit (PICU) after congenital heart surgery, who developed antimicrobial‐resistant septic shock and severe acute respiratory distress syndrome. Patient 2 was a 2‐year‐old male child admitted to the PICU with influenza A‐associated acute liver failure resulting in hyperammonemia, lactate acidosis, hemodynamic instability, and acute kidney failure. In both patients, hemadsorption with CytoSorb was initiated as an adjunctive rescue therapy to treat refractory multisystem organ failure. Improvement of laboratory and clinical parameters was observed within hours of treatment initiation. The application of the hemadsorber—developed for use in adults—proved simple and safe for use in both of our low‐weight pediatric patients.

High-frequency oscillatory ventilation in children: A systematic review and meta-analysis

BACKGROUND

High-frequency oscillatory ventilation (HFOV) is an alternative mechanical ventilation mode proposed to reduce ventilator-induced lung injuries and improve clinical outcomes. The aim of this study was to determine the effects of HFOV compared to conventional mechanical ventilation (CMV) when used in children with hypoxemic respiratory failure.

METHODS

The literature search was conducted to identify all studies published before December 2020. Eligible studies included a population aged between 28 days and 18 years old, presented original data from randomized controlled trials (RCTs) or observational studies, compared the use of HFOV with CMV. Meta-analyses of the pooled data were performed by using random-effects models with inverse-variance weighting.

RESULTS

A total of 11 studies (2605 cases) were included, most of them evaluating patients with acute respiratory distress syndrome. The mean age of participants was 8.2 months and the mean oxygenation index of those included in the RCTs was 24.4. The effect of HFOV on mortality was not significant, and clinically significant harm or benefit could not be excluded (risk ratio [RR], 0.93; 95% confidence interval [CI], 0.72 to 1.20). No significant difference between groups was found in duration of mechanical ventilation (-2.23; 95% CI, -5.07 to 0.61), treatment failure (RR, 0.28; 95% CI, 0.08 to 1.02), and occurrence of barotrauma (RR, 0.88; 95% CI, 0.39 to 1.99).

CONCLUSION

The scarce evidence currently available does not allow us to conclude that HFOV has advantages over CMV and further studies are needed to clarify its role in the treatment of acute hypoxemic respiratory failure in children.

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.

Disseminated Tularemia: Finding the Needle in the Haystack

We report a case of disseminated tularemia in a previously healthy 8-month-old male. This case highlights an atypical presentation of tularemia with multisystem organ involvement. The diagnosis was complicated by concurrent primary cytomegalovirus infection. Bronchoalveolar lavage culture confirmed the diagnosis. The patient was successfully treated with gentamicin. Pertinent literature reviewed.

Venoarterial to venovenous extracorporeal life support conversion in pediatric acute respiratory distress syndrome

In patients with pediatric acute respiratory distress syndrome (PARDS) and hemodynamic compromise who need venoarterial (VA) extracorporeal life support (ECLS), we have adopted a strategy to promote early VA-to-venovenous (VV) conversion since 2018. A single-center retrospective review was performed of all 22 patients who underwent ECLS for PARDS from 2008 to 2019. Variables were analyzed to determine factors affecting initial cannulation mode and in-hospital mortality. Outcomes were compared between before and after 2018. Of the 22 patients, 9 patients underwent initial VA-support. Small patient size and severe cardiopulmonary compromise prior to ECLS favored initial VA- over VV-support. Lactate level and vasoactive inotrope score at 24 hours post-ECLS initiation predicted in-hospital mortality. After 2018, all five patients with initial VA-support were converted to VV-support at 4.4 ± 1.3 days post-ECLS initiation without complications. In-hospital mortality decreased after 2018 (3/9) compared with before (10/13) (p = 0.041) despite longer ECLS run time (723.4 ± 384.2 vs 286.5 ± 235.1 hours, p = 0.003). The number of ECLS-related complications per ECLS 1000 run hours decreased after 2018 (7.2 ± 4.2 vs 46.9 ± 66.5, p = 0.063). Our strategy to promote early VA-to-VV conversion may be worth further evaluation in larger cohort studies.

Cytokine Panels and Pediatric Acute Respiratory Distress Syndrome: A Translational Investigation

OBJECTIVES

To identify and compare serum and lower respiratory tract fluid biomarkers of lung injury using well-characterized mouse models of lung injury. To explore the relationship between these preclinical biomarkers and clinical outcomes in a discovery cohort of pediatric patients with acute respiratory failure from pneumonia.

DESIGN

Prospective, observational cohort study.

SETTING

A basic science laboratory and the PICU of a tertiary-care children's hospital.

PATIENTS

PICU patients intubated for respiratory failure from a suspected respiratory infection.

INTERVENTIONS

Prospective enrollment and collection of lower respiratory tract fluid samples.

MEASUREMENTS AND MAIN RESULTS

C57BL6/J mice were intranasally inoculated with escalating doses of influenza A virus or toll-like receptor agonists to simulate varying degrees of lung injury. Serum and bronchoalveolar lavage fluid were measured for the presence of cytokines using commercially available multiplex cytokine assays. Elevated levels of C-C motif chemokine ligand 7 at the peak of inflammation in both bronchoalveolar lavage fluid and serum correlated with lethality, with the bronchoalveolar lavage fluid ratio of C-C motif chemokine ligand 7:C-C motif chemokine ligand 22 providing the best prediction in the mouse models. These preclinical biomarkers were examined in the plasma and lower respiratory tract fluid of a discovery cohort of pediatric patients with acute respiratory failure from pneumonia. The primary clinical outcome measure was ventilator-free days, with secondary outcomes of pediatric acute respiratory distress syndrome severity and mortality. Elevation in peak lower respiratory tract fluid C-C motif chemokine ligand 7:C-C motif chemokine ligand 22 ratios demonstrated a significant negative correlation with ventilator-free days (r = -0.805; p < 0.02).

CONCLUSIONS

This study provides evidence that lung immune profiling via lower respiratory tract fluid cytokine analysis is feasible and may provide insight into clinical outcomes. Further validation of markers, including the C-C motif chemokine ligand 7:C-C motif chemokine ligand 22 ratio in this limited study, in a larger cohort of patients is necessary.

Severe Coronavirus Disease 2019 Infection in an Adolescent Patient After Hematopoietic Stem Cell Transplantation

Infection with the severe acute respiratory syndrome coronavirus 2 causes severe acute lung injury in approximately 5% of infected adults, but few reports have been made of severe pediatric disease. We present an adolescent patient who contracted severe acute respiratory syndrome coronavirus 2 one week after a paternal haplo-identical hematopoietic stem cell transplant, with development of severe hyperferritinemic acute lung injury and macrophage activation-like syndrome. We present her case and a comparison of her laboratory data with those of a cohort of pediatric patients with coronavirus disease 2019 without severe disease.

Human Rhinovirus/Enterovirus in Pediatric Acute Respiratory Distress Syndrome

The role of human rhinovirus/enterovirus (HRV/HEV) in severe lower respiratory tract infections remains unclear. We characterized the respiratory status of children admitted to a large academic pediatric intensive care unit (PICU) who tested positive for only HRV/HEV. One hundred and fifty-five children met inclusion criteria with 62% requiring positive pressure respiratory support of 5 cm of water pressure or more within the first 24 hours of admission. Among them, 34% had SaO ₂ to FiO ₂ ratios of 264 or less with 22 patients (14%) meeting criteria for pediatric acute respiratory distress syndrome. HRV/HEV is associated with significant respiratory disease in children admitted to the PICU.

Case Report: Management Approach and Use of Extracorporeal Membrane Oxygenation for Diffuse Alveolar Hemorrhage After Pediatric Hematopoietic Cell Transplant

Introduction: Diffuse alveolar hemorrhage (DAH) is an early pulmonary complication of hematopoietic cell transplantation (HCT) associated with severe hypoxemic respiratory failure and mortality. Extracorporeal membrane oxygenation (ECMO) support is often used for respiratory failure refractory to conventional interventions; however, its use has been limited in HCT patients with DAH due to potential for worsening alveolar hemorrhage and reported high mortality. Case Presentation: We report two cases of DAH following HCT who developed refractory hypoxemic respiratory failure despite cessation of bleeding and were successfully supported with ECMO. Conclusion: DAH after HCT should not automatically preclude ECMO support; rather, these patients must be evaluated individually for ECMO within the context of their overall clinical picture.

Frequency of Pediatric Acute Respiratory Distress Syndrome Based on Oxygen Saturation Index in Pediatric Intensive Care Unit of a Developing Country

Objectives

To determine the frequency of pediatric acute respiratory distress syndrome based on oxygen saturation index in pediatric intensive care unit of a developing country.

Methods

We conducted a retrospective study of all children admitted in pediatric intensive care unit (PICU) of Aga Khan University Hospital, Karachi from July 2017 to June 2018 with respiratory rate >40 breaths/minute, shortness of breath, and bluish discoloration of skin and mucous membranes. The diagnosis of acute respiratory distress syndrome (ARDS) was made on the basis of standard operational definitions as mentioned (fulfilling criteria for ARDS).

Results

During the one-year study period 150 patients with age range of one month to 16 years were admitted fulfilling the inclusion criteria. Mean age was 38.27 ± 53.13 months, and 92 (61.33%) were male with male to female ratio of 1.6:1. Mean duration of symptoms was 1.23 ± 0.42 days. Frequency of pediatric acute respiratory distress syndrome using oxygen saturation index admitted in a pediatric ICU was 23 (15.33%) patients.

Conclusion

This study has shown that the frequency of pediatric acute respiratory distress syndrome is quite high.

Pediatric Acute Respiratory Distress Syndrome and Hypersensitivity Pneumonitis Related to E-cigarette Vaping

In recent years, electronic cigarettes (e-cigs) have been falsely advertised as safe alternatives to conventional smoking. We report a case involving a 16-year-old female who presented with fever, nonproductive cough, and shortness of breath after vaping e-cig/tetrahydrocannabinol dab pen. Her symptoms rapidly deteriorated and met diagnostic criteria for pediatric acute respiratory distress syndrome. Chest radiograph revealed extensive patchy airspace disease and computed tomography scan showed bilateral ground glass opacities. Bronchoalveolar lavage fluid revealed increased neutrophils, lymphocytosis, but absent eosinophilia. After the results of a comprehensive workup for infectious etiology returned negative, she was diagnosed with hypersensitivity pneumonitis and started on systemic corticosteroids.

Mechanical Ventilation Guided by Electrical Impedance Tomography in Children With Acute Lung Injury

Objectives

To provide proof-of-concept for a protocol applying a strategy of personalized mechanical ventilation in children with acute respiratory distress syndrome. Positive end-expiratory pressure and inspiratory pressure settings were optimized using real-time electrical impedance tomography aiming to maximize lung recruitment while minimizing lung overdistension.

Design

Prospective interventional trial.

Setting

Two PICUs.

Patients

Eight children with early acute respiratory distress syndrome (< 72 hr).

Interventions

On 3 consecutive days, electrical impedance tomography-guided positive end-expiratory pressure titration was performed by using regional compliance analysis. The Acute Respiratory Distress Network high/low positive end-expiratory pressure tables were used as patient's safety guardrails. Driving pressure was maintained constant. Algorithm includes the following: 1) recruitment of atelectasis: increasing positive end-expiratory pressure in steps of 4 mbar; 2) reduction of overdistension: decreasing positive end-expiratory pressure in steps of 2 mbar until electrical impedance tomography shows collapse; and 3) maintaining current positive end-expiratory pressure and check regional compliance every hour. In case of derecruitment start at step 1.

Measurements and Main Results

Lung areas classified by electrical impedance tomography as collapsed or overdistended were changed on average by -9.1% (95% CI, -13.7 to -4.4; p < 0.001) during titration. Collapse was changed by -9.9% (95% CI, -15.3 to -4.5; p < 0.001), while overdistension did not increase significantly (0.8%; 95% CI, -2.9 to 4.5; p = 0.650). A mean increase of the positive end-expiratory pressure level (1.4 mbar; 95% CI, 0.6-2.2; p = 0.008) occurred after titration. Global respiratory system compliance and gas exchange improved (global respiratory system compliance: 1.3 mL/mbar, 95% CI [-0.3 to 3.0], p = 0.026; Pao₂: 17.6 mm Hg, 95% CI [7.8-27.5], p = 0.0039; and Pao₂/Fio₂ ratio: 55.2 mm Hg, 95% CI [27.3-83.2], p < 0.001, all values are change in pre vs post).

Conclusions

Electrical impedance tomography-guided positive end-expiratory pressure titration reduced regional lung collapse without significant increase of overdistension, while improving global compliance and gas exchange in children with acute respiratory distress syndrome.

Use of Transpulmonary Pressure Monitoring in the Management of Extrapulmonary Pediatric Acute Respiratory Distress Syndrome With multi organ dysfunction syndrome (MODS): Are We Peepophobic?

Manipulation of positive end-expiratory pressure (PEEP) has been shown to improve the outcome in pediatric acute respiratory distress syndrome (PARDS), but the "ideal" PEEP, in which the compliance and oxygenation are maximized, while overdistension and undesirable hemodynamic effects are minimized, is yet to be determined. Also, for a given level of PEEP, transpulmonary pressure (TPP) may vary unpredictably from patient to patient. Patients with high pleural pressure who are on conventional ventilator settings under inflation may cause hypoxemia. In such patients, raising PEEP to maintain a positive TPP might improve aeration and oxygenation without causing overdistension. We report a case of PARDS, who was managed using real-time esophageal pressure monitoring using the AVEA ventilator and thereby adjusting PEEP to maintain the positive TPP.

A Novel Pathway in Pediatric Acute Respiratory Distress Syndrome

RATIONALE

MMPs (Matrix metalloproteinases) and their endogenous tissue inhibitors may contribute to lung injury through extracellular matrix degradation and modulation of inflammation and fibrosis.

OBJECTIVES

To test for an association between MMP pathway proteins and inflammation, endothelial dysfunction, and clinical outcomes.

METHODS

We measured MMPs in plasma collected on acute respiratory distress syndrome (ARDS) Day 1 from 235 children at five hospitals between 2008 and 2017. We used latent class analysis to identify patients with distinct MMP profiles and then associated those profiles with markers of inflammation (IL-1RA, -6, -8, -10, and -18; macrophage inflammatory protein-1α and -1β; tumor necrosis factor-α and -R2), endothelial injury (angiopoietin-2, von Willebrand factor, soluble thrombomodulin), impaired oxygenation (PaO2/FiO2 [P/F] ratio, oxygenation index), morbidity, and mortality.

MEASUREMENTS AND MAIN RESULTS

In geographically distinct derivation and validation cohorts, approximately one-third of patients demonstrated an MMP profile characterized by elevated MMP-1, -2, -3, -7, and -8 and tissue inhibitor of metalloproteinase-1 and -2; and depressed active and total MMP-9. This MMP profile was associated with multiple markers of inflammation, endothelial injury, and impaired oxygenation on Day 1 of ARDS, and conferred fourfold increased odds of mortality or severe morbidity independent of the P/F ratio and other confounders (95% confidence interval, 2.1-7.6; P < 0.001). Logistic regression using both the P/F ratio and MMP profiles was superior to the P/F ratio alone in prognosticating mortality or severe morbidity (area under the receiver operating characteristic curve, 0.75; 95% confidence interval, 0.68-0.82 vs. area under the receiver operating characteristic curve, 0.66; 95% confidence interval, 0.58-0.73; P = 0.009).

CONCLUSIONS

Pediatric patients with ARDS have specific plasma MMP profiles associated with inflammation, endothelial injury, morbidity, and mortality. MMPs may play a role in the pathobiology of children with ARDS.

Sepsis and Pediatric Acute Respiratory Distress Syndrome

The epidemiology of the acute respiratory distress syndrome (ARDS) in pediatric sepsis is poorly defined. With significant data extrapolated from adult studies in sepsis and ARDS, sometimes with uncertain applicability, better pediatric-specific guidelines and dedicated investigations are warranted. The recent publication of a consensus definition for pediatric ARDS (PARDS) is the first step in addressing this knowledge gap. The aim of this review is to frame our current understanding of PARDS as it relates to pediatric sepsis, encompassing epidemiology, pathophysiology, and management. We argue that addressing the role of PARDS in pediatric sepsis requires significant attention to details with respect to how PARDS and sepsis are defined to accurately describe their epidemiology, natural history, and outcomes. Finally, we highlight certain aspects of PARDS management as they relate to the septic child and offer suggestion for future directions in this field.

Variability in Pediatric Ideal Body Weight Calculation: Implications for Lung-Protective Mechanical Ventilation Strategies in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

No gold standard for ideal body weight determination in children exists. We aimed to compare four methods of ideal body weight calculation and determine level of agreement between methods and impact of measurement variance on tidal volumes prescribed in mechanically ventilated pediatric acute respiratory distress syndrome.

DESIGN

Post hoc analysis of four multicenter pediatric acute respiratory distress syndrome studies.

SETTING

Twenty-six academic PICUs.

PATIENTS

Five hundred eighty-nine patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Ideal body weight was calculated by four common methods: National Center for Health Statistics, McLaren, Moore, and body mass index, and compared in three ways: 1) determine the proportion of the cohort for which each method could successfully calculate ideal body weight; 2) compare the level of agreement between the ideal body weight methods by Bland-Altman analysis; and 3) evaluate the difference in tidal volume when 6 mL/kg ideal body weight was prescribed. We a priori defined the better method to be one that could calculate ideal body weight in most subjects, had good agreement with other methods, and led to a lower tidal volume. Only 55% could have ideal body weight measured by all four methods. National Center for Health Statistics, McLaren, and Moore methods could calculate ideal body weight in greater than or equal to 90%, whereas body mass index method was successful in only 61% because of no body mass index validation in less than 2-year-olds. In comparing each method to the others, there was great variance, particularly in greater than or equal to 10-year-olds. This variance was greatest between Moore and body mass index methods with greater than or equal to 10 kg difference in ideal body weight in some subjects. The McLaren method had the best agreement with all other methods, and yielded similar prescribed tidal volume in 2- to 10-year-olds and lower tidal volume in greater than or equal to 10 years old.

CONCLUSIONS

There is substantial variation in calculated ideal body weight among four commonly used methods, particularly in adolescents. Since varying ideal body weight may lead to discrepancies in pediatric acute respiratory distress syndrome care, a standard approach to ideal body weight measurement is needed. We recommend the McLaren method to calculate ideal body weight in children with pediatric acute respiratory distress syndrome until a gold standard method is validated.

High frequency oscillatory ventilation versus conventional mechanical ventilation in pediatric acute respiratory distress syndrome: A randomized controlled study

El-Nawawy A, Moustafa A, Heshmat H, Abouahmed A. High frequency oscillatory ventilation versus conventional mechanical ventilation in pediatric acute respiratory distress syndrome: A randomized controlled study. Turk J Pediatr 2017; 59: 130-143. The aim of this prospective randomized study is to compare the outcomes of the early use of either high frequency oscillation (HFO) or conventional mechanical ventilation (CMV) in patients with pediatric acute respiratory distress syndrome (PARDS). We allocated two hundred PARDS patients over 5 years in 1:1 ratio to either mode. The HFO group showed a significantly higher median partial arterial oxygen pressure to fraction of inspired oxygen (PaO2/FiO2) values after 24 hours of enrollment (p=0.011), higher oxygenation index (OI) decrease percent (p=0.004) and lower cross-over rates (p < 0.001), whereas no differences in 30-day mortality, length of stay (LOS) or ventilation days (p=0.77, p=0.28, p=0.65 respectively). The second day values (after 24 hours) of both OI and PaO < sub > 2 < /sub > /FiO < sub > 2 < /sub > were found to be more significant discriminators for mortality when compared to the baseline values (cutoff values > 8.5, ≤139 respectively). PARDS patients with baseline OI > 16 had a better chance of survival if initially ventilated with the HFO (p=0.004). Although the HFO mode appeared to be a safe mode with a significant better oxygenation improvement (after the first 24 hours) and fewer cross-over rates, it failed to show differences as regards mortality or LOS when compared to the CMV adopting protective lung strategy. In PARDS, HFO had a superior advantage in improving oxygenation, yet with no significant mortality improvement, as multi-organ dysfunction syndrome (MODS) was the most common cause of death in our study and not refractory hypoxemia which is the main problem in PARDS; highlighting that mortality in PARDS is multi-factorial and may not depend only on how fast oxygenation improves.

Pediatric acute respiratory distress syndrome associated with human metapneumovirus and respiratory syncytial virus

OBJECTIVES

To study the incidence, risk factors, clinical course, and outcome of ARDS in children with HMP and RSV.

WORKING HYPOTHESIS

We hypothesized that ARDS in children with HMP was similar in incidence, risk factors, clinical course, and outcomes to ARDS in children with RSV.

STUDY DESIGN

Retrospective, observational study over 2 years.

PATIENT-SUBJECT SELECTION

Patients included were <18 years old with HMP or RSV detected from nasopharyngeal specimens by commercial reverse transcriptase polymerase chain reaction assay admitted to a study site.

METHODOLOGY

We described the incidence of ARDS within 1 week following the detection of HMP or RSV using recently developed Pediatric ARDS (PARDS) criteria. We also assessed risk factors, clinical course, and outcomes of children in the PICU with HMP or RSV and PARDS or non-PARDS.

RESULTS

We identified 57 patients with HMP and 161 patients with RSV: the proportions of patients with either virus who developed PARDS (HMP: 23%, RSV: 20%) and severe PARDS (HMP: 9%, RSV: 7%) were similar, as were the proportions of patients with acute (or acute-on-chronic) respiratory failure who developed PARDS (HMP: 41%, RSV: 31%). In a logistic regression model, risk factors associated with PARDS included neurologic comorbidity and PIM 3 probability of mortality, but not virus type. The risk factors, clinical course, and outcomes were similar for patients with PARDS associated with HMP and RSV.

CONCLUSIONS

About 1/3 of children with HMP or RSV and acute (or acute-on-chronic) respiratory failure developed PARDS. Children with either virus and a neurologic comorbidity or an increased PIM 3 probability of mortality were at increased risk for PARDS.

Does Extracorporeal Membrane Oxygenation Improve Survival in Pediatric Acute Respiratory Failure?

RATIONALE

Extracorporeal membrane oxygenation (ECMO) has supported gas exchange in children with severe respiratory failure for more than 40 years, without ECMO efficacy studies.

OBJECTIVES

To compare the mortality and functional status of children with severe acute respiratory failure supported with and without ECMO.

METHODS

This cohort study compared ECMO-supported children to pair-matched non-ECMO-supported control subjects with severe acute respiratory distress syndrome (ARDS). Both individual case matching and propensity score matching were used. The study sample was selected from children enrolled in the cluster-randomized RESTORE (Randomized Evaluation of Sedation Titration for Respiratory Failure) clinical trial. Detailed demographic and daily physiologic data were used to match patients. The primary endpoint was in-hospital mortality. Secondary outcomes included hospital-free days, ventilator-free days, and change in functional status at hospital discharge.

MEASUREMENTS AND MAIN RESULTS

Of 2,449 children in the RESTORE trial, 879 (35.9%) non-ECMO-supported patients with severe ARDS were eligible to match to 61 (2.5%) ECMO-supported children. When individual case matching was used (60 matched pairs), the in-hospital mortality rate at 90 days was 25% (15 of 60) for both the ECMO-supported and non-ECMO-supported children (P > 0.99). With propensity score matching (61 matched pairs), the ECMO-supported in-hospital mortality rate was 15 of 61 (25%), and the non-ECMO-supported hospital mortality rate was 18 of 61 (30%) (P = 0.70). There was no difference between ECMO-supported and non-ECMO-supported patients in any secondary outcomes.

CONCLUSIONS

In children with severe ARDS, our results do not demonstrate that ECMO-supported children have superior outcomes compared with non-ECMO-supported children. Definitive answers will require a rigorous multisite randomized controlled trial.

Comparison of Prevalence and Outcomes of Pediatric Acute Respiratory Distress Syndrome Using Pediatric Acute Lung Injury Consensus Conference Criteria and Berlin Definition

OBJECTIVES

Our objective was to compare the prevalence and outcomes of pediatric acute respiratory distress syndrome using the Pediatric Acute Lung Injury Consensus Conference (PALICC) criteria and Berlin definitions.

METHODS

We screened case records of all children aged 1 month to 17 years of age admitted to the Pediatric Intensive Care Unit (PICU) over a 3-year period (2015-2017) for presence of any respiratory difficulty at admission or during PICU stay. We applied both PALICC and Berlin criteria to these patients. Data collection included definition and outcome related variables. Data were compared between the "PALICC only group" and the "Berlin with or without PALICC" group using Stata 11.

RESULTS

Of a total of 615 admissions, 246 were identified as having respiratory difficulty at admission or during PICU stay. A total of 61 children (prevalence 9.9%; 95% CI: 7.8-12.4) fulfilled the definition of acute respiratory distress syndrome (ARDS) with either of the two criteria. While 60 children (98%) fulfilled PALICC criteria, only 26 children (43%) fulfilled Berlin definition. There was moderate agreement between the two definitions (Kappa: 0.51; 95% CI: 0.40-0.62; observed agreement 85%). Greater proportion of patients had severe ARDS in the "Berlin with or without PALICC group" as compared to the "PALICC only" group (50 vs. 19%). There was no difference between the groups with regard to key clinical outcomes such as duration of ventilation (7 vs. 8 days) or mortality [51.4 vs. 57.7%: RR (95% CI): 0.99 (0.64-1.5)].

CONCLUSION

In comparison to Berlin definition, the PALICC criteria identified more number of patients with ARDS. Proportion with severe ARDS and complications was greater in the "Berlin with or without PALICC" group as compared to the "PALICC only" group. There were no differences in clinical outcomes between the groups.

Potential Acceptability of a Pediatric Ventilator Management Computer Protocol

OBJECTIVES

To examine issues regarding the granularity (size/scale) and potential acceptability of recommendations in a ventilator management protocol for children with pediatric acute respiratory distress syndrome.

DESIGN

Survey/questionnaire.

SETTING

The eight PICUs in the Collaborative Pediatric Critical Care Research Network.

PARTICIPANTS

One hundred twenty-two physicians (attendings and fellows).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We used an online questionnaire to examine attitudes and assessed recommendations with 50 clinical scenarios. Overall 80% of scenario recommendations were accepted. Acceptance did not vary by provider characteristics but did vary by ventilator mode (high-frequency oscillatory ventilation 83%, pressure-regulated volume control 82%, pressure control 75%; p = 0.002) and variable adjusted (ranging from 88% for peak inspiratory pressure and 86% for FIO2 changes to 69% for positive end-expiratory pressure changes). Acceptance did not vary based on child size/age. There was a preference for smaller positive end-expiratory pressure changes but no clear granularity preference for other variables.

CONCLUSIONS

Although overall acceptance rate for scenarios was good, there was little consensus regarding the size/scale of ventilator setting changes for children with pediatric acute respiratory distress syndrome. An acceptable protocol could support robust evaluation of ventilator management strategies. Further studies are needed to determine if adherence to an explicit protocol leads to better outcomes.

Variability in Usual Care Mechanical Ventilation for Pediatric Acute Respiratory Distress Syndrome: Time for a Decision Support Protocol?

OBJECTIVES

Although pediatric intensivists philosophically embrace lung protective ventilation for acute lung injury and acute respiratory distress syndrome, we hypothesized that ventilator management varies. We assessed ventilator management by evaluating changes to ventilator settings in response to blood gases, pulse oximetry, or end-tidal CO2. We also assessed the potential impact that a pediatric mechanical ventilation protocol adapted from National Heart Lung and Blood Institute acute respiratory distress syndrome network protocols could have on reducing variability by comparing actual changes in ventilator settings to those recommended by the protocol.

DESIGN

Prospective observational study.

SETTING

Eight tertiary care U.S. PICUs, October 2011 to April 2012.

PATIENTS

One hundred twenty patients (age range 17 d to 18 yr) with acute lung injury/acute respiratory distress syndrome.

MEASUREMENTS AND MAIN RESULTS

Two thousand hundred arterial and capillary blood gases, 3,964 oxygen saturation by pulse oximetry, and 2,757 end-tidal CO2 values were associated with 3,983 ventilator settings. Ventilation mode at study onset was pressure control 60%, volume control 19%, pressure-regulated volume control 18%, and high-frequency oscillatory ventilation 3%. Clinicians changed FIO2 by ±5 or ±10% increments every 8 hours. Positive end-expiratory pressure was limited at ~10 cm H2O as oxygenation worsened, lower than would have been recommended by the protocol. In the first 72 hours of mechanical ventilation, maximum tidal volume/kg using predicted versus actual body weight was 10.3 (8.5-12.9) (median [interquartile range]) versus 9.2 mL/kg (7.6-12.0) (p < 0.001). Intensivists made changes similar to protocol recommendations 29% of the time, opposite to the protocol's recommendation 12% of the time and no changes 56% of the time.

CONCLUSIONS

Ventilator management varies substantially in children with acute respiratory distress syndrome. Opportunities exist to minimize variability and potentially injurious ventilator settings by using a pediatric mechanical ventilation protocol offering adequately explicit instructions for given clinical situations. An accepted protocol could also reduce confounding by mechanical ventilation management in a clinical trial.

High-frequency oscillatory ventilation is an effective treatment for severe pediatric acute respiratory distress syndrome with refractory hypoxemia

Background and purpose

Early or primary application of high-frequency oscillatory ventilation (HFOV) has been recently suggested not to offer benefit to patients with acute respiratory distress syndrome (ARDS). However, the rescue effects of HFOV on severe pediatric acute respiratory distress syndrome (PARDS) with hypoxemia refractory to conventional mechanical ventilation (CMV) remain unclear. This study aimed to determine whether severe PARDS children would benefit from HFOV when oxygenation deteriorated on CMV and to identify any potential risk factors related to mortality.

Patients and methods

In a retrospective and observational study, 48 children with severe PARDS between January 2009 and July 2015 were divided into two groups: 26 in HFOV group and 22 in CMV group. Data regarding demographic, underlying conditions, arterial blood gases and clinical outcomes were collected and analyzed.

Results

The arterial partial pressure of oxygen (PaO₂)/fraction of inspiration oxygen (FiO₂) ratio and PaO₂ improved significantly during HFOV, whereas arterial partial pressure of carbon dioxide (PaCO₂) and oxygenation index decreased. There was no statistical difference in the in-hospital mortality between the groups (P=0.367). The odds ratio of survival in HFOV group was 2.74 (95% confidence interval 0.52 to 14.58, P=0.237). The pediatric intensive care unit length of stay and total ventilation duration were longer in HFOV group (P=0.048 and P=0.000, respectively). Vasoactive agents were used more frequently in HFOV group (P=0.007). The incidence of new air leak was similar between the two groups (P=0.674). The presence of multiple organ dysfunction syndrome and heavier body weight were identified as predictors of mortality in the HFOV group (P=0.006 and P=0.020, respectively).

Conclusion

HFOV as an efficient alternative therapy could significantly improve hypoxemia and promote CO₂ removal in severe PARDS children when oxygenation progressively worsens on CMV.

Poor Adherence to Lung-Protective Mechanical Ventilation in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To determine the frequency of low-tidal volume ventilation in pediatric acute respiratory distress syndrome and assess if any demographic or clinical factors improve low-tidal volume ventilation adherence.

DESIGN

Descriptive post hoc analysis of four multicenter pediatric acute respiratory distress syndrome studies.

SETTING

Twenty-six academic PICU.

PATIENTS

Three hundred fifteen pediatric acute respiratory distress syndrome patients.

MEASUREMENTS AND MAIN RESULTS

All patients who received conventional mechanical ventilation at hours 0 and 24 of pediatric acute respiratory distress syndrome who had data to calculate ideal body weight were included. Two cutoff points for low-tidal volume ventilation were assessed: less than or equal to 6.5 mL/kg of ideal body weight and less than or equal to 8 mL/kg of ideal body weight. Of 555 patients, we excluded 240 for other respiratory support modes or missing data. The remaining 315 patients had a median PaO2-to-FIO2 ratio of 140 (interquartile range, 90-201), and there were no differences in demographics between those who did and did not receive low-tidal volume ventilation. With tidal volume cutoff of less than or equal to 6.5 mL/kg of ideal body weight, the adherence rate was 32% at hour 0 and 33% at hour 24. A low-tidal volume ventilation cutoff of tidal volume less than or equal to 8 mL/kg of ideal body weight resulted in an adherence rate of 58% at hour 0 and 60% at hour 24. Low-tidal volume ventilation use was no different by severity of pediatric acute respiratory distress syndrome nor did adherence improve over time. At hour 0, overweight children were less likely to receive low-tidal volume ventilation less than or equal to 6.5 mL/kg ideal body weight (11% overweight vs 38% nonoverweight; p = 0.02); no difference was noted by hour 24. Furthermore, in the overweight group, using admission weight instead of ideal body weight resulted in misclassification of up to 14% of patients as receiving low-tidal volume ventilation when they actually were not.

CONCLUSIONS

Low-tidal volume ventilation is underused in the first 24 hours of pediatric acute respiratory distress syndrome. Age, Pediatric Risk of Mortality-III, and pediatric acute respiratory distress syndrome severity were not associated with improved low-tidal volume ventilation adherence nor did adherence improve over time. Overweight children were less likely to receive low-tidal volume ventilation strategies in the first day of illness.

Cortisol Correlates with Severity of Illness and Poorly Reflects Adrenal Function in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVE

To test the association between random cortisol and severity of illness in a "real-world" application of current guidelines.

STUDY DESIGN

We performed a secondary analysis of a prospective observational cohort of acute respiratory distress syndrome (ARDS). Children with ARDS and vasopressor-dependent shock were identified and random cortisol levels before potential hydrocortisone initiation recorded. The cohort was dichotomized to cortisol < 18 and ≥ 18 μg/dL, and hydrocortisone use and outcomes compared.

RESULTS

Of 357 children with ARDS, 155 (15 nonsurvivors; 10%) had vasopressors initiated with cortisol drawn before possible hydrocortisone use. Patients with cortisol < 18 μg/dL had lower severity of illness scores, fewer organ failures, and lower vasopressor scores (all rank-sum P < .05). No benefit was seen with hydrocortisone in either the entire cohort, or when dichotomized by a cortisol cutoff of 18 μg/dL. In patients with cortisol ≥ 18 μg/dL, hydrocortisone was associated with increased mortality after adjustment for either organ dysfunction or vasopressor score.

CONCLUSIONS

In children with ARDS with vasopressor-dependent shock, low cortisol correlated with lower severity of illness. Random cortisol was a poor method of diagnosing adrenal insufficiency, and a strategy of hydrocortisone replacement for cortisol < 18 μg/dL did not target a population likely to benefit from hydrocortisone. Future guidelines should reconsider using random cortisol levels alone for assessing adrenal function.

Early High-Frequency Oscillatory Ventilation in Pediatric Acute Respiratory Failure. A Propensity Score Analysis

RATIONALE

The use of high-frequency oscillatory ventilation (HFOV) for acute respiratory failure in children is prevalent despite the lack of efficacy data.

OBJECTIVES

To compare the outcomes of patients with acute respiratory failure managed with HFOV within 24-48 hours of endotracheal intubation with those receiving conventional mechanical ventilation (CMV) and/or late HFOV.

METHODS

This is a secondary analysis of data from the RESTORE (Randomized Evaluation of Sedation Titration for Respiratory Failure) study, a prospective cluster randomized clinical trial conducted between 2009 and 2013 in 31 U.S. pediatric intensive care units. Propensity score analysis, including degree of hypoxia in the model, compared the duration of mechanical ventilation and mortality of patients treated with early HFOV matched with those treated with CMV/late HFOV.

MEASUREMENTS AND MAIN RESULTS

Among 2,449 subjects enrolled in RESTORE, 353 patients (14%) were ever supported on HFOV, of which 210 (59%) had HFOV initiated within 24-48 hours of intubation. The propensity score model predicting the probability of receiving early HFOV included 1,064 patients (181 early HFOV vs. 883 CMV/late HFOV) with significant hypoxia (oxygenation index ≥ 8). The degree of hypoxia was the most significant contributor to the propensity score model. After adjusting for risk category, early HFOV use was associated with a longer duration of mechanical ventilation (hazard ratio, 0.75; 95% confidence interval, 0.64-0.89; P = 0.001) but not with mortality (odds ratio, 1.28; 95% confidence interval, 0.92-1.79; P = 0.15) compared with CMV/late HFOV.

CONCLUSIONS

In adjusted models including important oxygenation variables, early HFOV was associated with a longer duration of mechanical ventilation. These analyses make supporting the current approach to HFOV less convincing.

Circulating nucleosomes are associated with mortality in pediatric acute respiratory distress syndrome

Mechanisms underlying pediatric acute respiratory distress syndrome (PARDS) are poorly understood. The recent implication of circulating nucleosomes as pathogenic in sepsis and trauma-associated ARDS in adults led us to investigate the significance of nucleosomes in PARDS. We conducted a prospective, observational study on children with PARDS at the Children's Hospital of Philadelphia between July 2014 and September 2015. Plasma was collected within 48 h of PARDS onset and nucleosomes quantified by enzyme-linked immunosorbent assay. Samples from 76 children with PARDS (11 deaths, 14%) were collected early [median 15 (IQR 7, 21) h] after PARDS onset. Nucleosome levels were higher in nonsurvivors [0.59 AU (IQR 0.46, 0.84)] relative to survivors [0.21 AU (IQR 0.08, 0.33), rank sum P < 0.001]. Nucleosome levels were not associated with either Berlin (P = 0.845) or PALICC (P = 0.886) oxygenation categories, nor with etiology of PARDS (P = 0.527). Nucleosomes were correlated with increasing numbers of nonpulmonary organ failures (P = 0.009 for trend), and were higher in patients whose PaO2 /FiO2 worsened (P = 0.012) over the first 72 h of PARDS. In regression analysis, nucleosome levels were independently associated with mortality after adjusting for either age, severity of illness score, number of nonpulmonary organ failures, vasopressor score, or PaO2 /FiO2 (all P < 0.05). In conclusion, plasma nucleosome levels in early PARDS were associated with increased mortality, correlated with number of nonpulmonary organ failures, and preceded worsening oxygenation. The potential utility of this biomarker for prognostication, risk stratification, and mechanistic insight should be investigated further.

Role of Inhaled Nitric Oxide in the Management of Severe Acute Respiratory Distress Syndrome

To date, there have been several systematic reviews with meta-analysis that have shown no reduction in mortality with the use of inhaled nitric oxide (iNO) in patients with acute respiratory distress syndrome (ARDS). Importantly, these reports fail to make a distinction between the pediatric and adult patient. The number of adult patients in these reviews are far greater than the number of pediatric patients, which makes it difficult to interpret the data regarding the role of iNO on the pediatric population. Extrapolating data from the adult population to the pediatric population is complicated as we know that physiology and the body's response to disease can be different between adult and pediatric patients. iNO has been demonstrated to improve outcomes in term and near-term infants with hypoxic respiratory failure associated with pulmonary hypertension. Recently, Bronicki et al. published a prospective randomized control trial investigating the impact of iNO on the pediatric patient population with acute respiratory failure. In this study, a benefit of decreased duration of mechanical ventilation and an increased rate of ECMO-free survival was demonstrated in patients who were randomized to receiving iNO, suggesting that there may be benefit to the use of iNO in pediatric ARDS (PARDS) that has not been demonstrated in adults. iNO has repeatedly been shown to transiently improve oxygenation in all age groups, and yet neonates and pediatric patients have shown improvement in other outcomes that have not been seen in adults. The mechanism that explains improvement with the use of iNO in these patient populations are not well understood but does not appear to be solely a result of sustained improvement in oxygenation. There are physiologic studies that suggest alternative mechanisms for explaining the positive effects of iNO, such as platelet aggregation inhibition and reduction in systemic inflammation. Hence, the role of iNO by various mechanisms and in various age groups warrants further investigation.