Acute lung injury in pediatric intensive care in Australia and New Zealand: a prospective, multicenter, observational study

Association between Age and Mortality in Pediatric and Adult Acute Respiratory Distress Syndrome

Rationale: The epidemiology, management, and outcomes of acute respiratory distress syndrome (ARDS) differ between children and adults, with lower mortality rates in children despite comparable severity of hypoxemia. However, the relationship between age and mortality is unclear.Objective: We aimed to define the association between age and mortality in ARDS, hypothesizing that it would be nonlinear.Methods: We performed a retrospective cohort study using data from two pediatric ARDS observational cohorts (n = 1,236), multiple adult ARDS trials (n = 5,547), and an adult observational ARDS cohort (n = 1,079). We aligned all datasets to meet Berlin criteria. We performed unadjusted and adjusted logistic regression using fractional polynomials to assess the potentially nonlinear relationship between age and 90-day mortality, adjusting for sex, PaO2/FiO2, immunosuppressed status, year of study, and observational versus randomized controlled trial, treating each individual study as a fixed effect.Measurements and Main Results: There were 7,862 subjects with median ages of 4 years in the pediatric cohorts, 52 years in the adult trials, and 61 years in the adult observational cohort. Most subjects (43%) had moderate ARDS by Berlin criteria. Ninety-day mortality was 19% in the pediatric cohorts, 33% in the adult trials, and 67% in the adult observational cohort. We found a nonlinear relationship between age and mortality, with mortality risk increasing at an accelerating rate between 11 and 65 years of age, after which mortality risk increased more slowly.Conclusions: There was a nonlinear relationship between age and mortality in pediatric and adult ARDS.

High-frequency oscillatory ventilation versus conventional ventilation in pediatric patients with acute lung injury: outcomes evaluation

Background

With the development of medical technology and advancements of intensive care units, many types of mechanical ventilators are recruited in the management of acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). We evaluated the outcome of the high-frequency oscillatory ventilation (HFOV) compared to conventional mechanical ventilation (CMV) in pediatric patients with critical respiratory situations mainly ALI or ARDS. A prospective cohort study was performed from 2019 to 2020 in the pediatric intensive care unit (PICU). The following data were recorded: demographic and clinical data, length of PICU stay, mechanical ventilation days, and mortality percentages.

Results

Fifty cases who fulfilled the inclusion criteria were divided into two groups, 24 patients on HFOV from the start and the other 26 were admitted on rescue HFOV after the failure of CMV. There was no statistically significant difference between the two groups regarding the age (p = 0.571) and the oxygenation index (OI) (p = 0.651). Early HFOV demonstrated shorter length of PICU stay and fewer days on mechanical ventilation. The mortality rate was less with the application of early HFOV compared to rescue HFOV.

Conclusions

Early admission on HFOV can be a safe option in the management of patients with critical lung situation as ARDS/ALI.

Nonadherence to appropriate tidal volume and PEEP in children with pARDS at a single center

BACKGROUND

Low tidal volume and adequate positive end-expiratory pressure (PEEP) are evidence-based approaches for pediatric acute respiratory distress syndrome (pARDS), however, data are limited regarding their use since pARDS guidelines were revised in 2015.

OBJECTIVE

To identify prevalence of, and factors associated with, nonadherence to appropriate tidal volume and PEEP in children with pARDS.

METHODS

Retrospective cohort study of children 1 month to <18 years with pARDS who received invasive mechanical ventilation from 2016 to 2018 in a single pediatric intensive care unit (PICU).

RESULTS

At 24 h after meeting pARDS criteria, 48/86 (56%) patients received tidal volume ≤8 ml/kg of ideal body weight and 45/86 (52%) received appropriate PEEP, with 22/86 (26%) receiving both. Among patients ≥2 years of age, a lower proportion of patients with overweight/obesity (9/25, 36%) had appropriate tidal volume versus those in the normal or underweight category (16/22, 73%, p = 0.02). When FIO2 was ≥50%, PEEP was appropriate in 19/60 (32%) cases versus 26/26 (100%) with FIO2  < 50% (p < 0.0001). pARDS was documented in the progress note in 7/86 (8%) patients at 24 h. Severity of pARDS, documentation in the progress note, and other clinical factors were not significantly associated with use of appropriate tidal volume and PEEP, however pARDS was documented more commonly in patients with severe pARDS.

CONCLUSIONS

In a single PICU in the United States, children with pARDS did not receive appropriate tidal volume for ideal body weight nor PEEP. Targets for improving tidal volume and PEEP adherence may include overweight patients and those receiving FIO2  ≥ 50%, respectively.

Epidemiology of Acute Respiratory Distress Syndrome in Pediatric Intensive Care Unit: Single-center Experience

Background

Acute respiratory distress syndrome (ARDS) is characterized by dysregulated inflammation resulting in hypoxemia and respiratory failure and causes both morbidity and mortality.

Objectives

To describe the clinical profile, outcome, and predictors of mortality in ARDS in children admitted to the Pediatric intensive care unit.

Materials and methods

This is a single-center retrospective study conducted at a tertiary referral hospital in a 12-bed PICU involving children (1 month to 18 years) with ARDS as defined by Pediatric Acute Lung Injury Consensus Conference (PALICC) guidelines, over a period of 5 years (2016–2020). Demographic, clinical, and laboratory details at onset and during PICU stay were collected. Predictors of mortality were compared between survivors and non-survivors.

Results

We identified 89 patients with ARDS. The median age at presentation was 76 months (12–124 months). The most common precipitating factor was pneumonia (66%). The majority of children (35.9%) had moderate ARDS. Overall mortality was 33% with more than half belonging to severe ARDS group (58%). On Kaplan–Meier survival curve analysis, the mean time to death was shorter in the severe ARDS group as compared to other groups. Multiorgan dysfunction was present in 46 (51.6%) of the cases. Non-survivors had higher mean pediatric logistic organ dysfunction (PELOD2) on day 1. PRISM III at admission, worsening trends of ventilator and oxygenation parameters (OI, P/F, MAP, and PEEP) independently predicted mortality after multivariate analysis.

Conclusion

High PRISM score predicts poor outcome, and worsening trends of ventilator and oxygenation parameters (OI, P/F, MAP, and PEEP) are associated with mortality.

How to cite this article

Pujari CG, Lalitha AV, Raj JM, Kavilapurapu A. Epidemiology of Acute Respiratory Distress Syndrome in Pediatric Intensive Care Unit: Single-center Experience. Indian J Crit Care Med 2022;26(8):949–955.

Mechanical Ventilation in Pediatric and Neonatal Patients

Pediatric acute respiratory distress syndrome (PARDS) remains a significant cause of morbidity and mortality, with mortality rates as high as 50% in children with severe PARDS. Despite this, pediatric lung injury and mechanical ventilation has been poorly studied, with the majority of investigations being observational or retrospective and with only a few randomized controlled trials to guide intensivists. The most recent and universally accepted guidelines for pediatric lung injury are based on consensus opinion rather than objective data. Therefore, most neonatal and pediatric mechanical ventilation practices have been arbitrarily adapted from adult protocols, neglecting the differences in lung pathophysiology, response to injury, and co-morbidities among the three groups. Low tidal volume ventilation has been generally accepted for pediatric patients, even in the absence of supporting evidence. No target tidal volume range has consistently been associated with outcomes, and compliance with delivering specific tidal volume ranges has been poor. Similarly, optimal PEEP has not been well-studied, with a general acceptance of higher levels of F_iO₂ and less aggressive PEEP titration as compared with adults. Other modes of ventilation including airway pressure release ventilation and high frequency ventilation have not been studied in a systematic fashion and there is too little evidence to recommend supporting or refraining from their use. There have been no consistent outcomes among studies in determining optimal modes or methods of setting them. In this review, the studies performed to date on mechanical ventilation strategies in neonatal and pediatric populations will be analyzed. There may not be a single optimal mechanical ventilation approach, where the best method may simply be one that allows for a personalized approach with settings adapted to the individual patient and disease pathophysiology. The challenges and barriers to conducting well-powered and robust multi-institutional studies will also be addressed, as well as reconsidering outcome measures and study design.

Is there a role for lung-protective ventilation in healthy children?

Lung-protective ventilation (LPV) has been adopted in the theater environment as a strategy to reduce pulmonary complications under anesthesia. Postoperative pulmonary complications are not infrequent and may have significant implications on the postoperative length of stay as well as the morbidity and mortality of pediatric patients. There is evidence in the adult literature to suggest that intraoperative LPV strategies may reduce the risk of such complications. The utility of LPV strategies in healthy children is not well researched, and the data from critical care studies appear to be conflicting. To ascertain the value of intraoperative LPV in pediatric patients, it is important to understand the pathophysiology of pediatric ventilator-induced lung injury and the basis of LPV strategies. The current evidence in adult and pediatric populations, including pediatric intensive care, is reviewed to gain insight into the role and value of intraoperative LPV for pediatric patients.

Venovenous vs. Venoarterial Extracorporeal Membrane Oxygenation in Infection-Associated Severe Pediatric Acute Respiratory Distress Syndrome: A Prospective Multicenter Cohort Study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been increasingly used as rescue therapy for severe pediatric acute respiratory distress syndrome (PARDS) over the past decade. However, a contemporary comparison of venovenous (VV) and venoarterial (VA) ECMO in PARDS has yet to be well described. Therefore, the objective of our study was to assess the difference between VV and VA ECMO in efficacy and safety for infection-associated severe PARDS patients.

METHODS

This prospective multicenter cohort study included patients with infection-associated severe PARDS who received VV or VA ECMO in pediatric intensive care units (PICUs) of eight university hospitals in China between December 2018 to June 2021. The primary outcome was in-hospital mortality. Secondary outcomes included ECMO weaning rate, duration of ECMO and mechanical ventilation (MV), ECMO-related complications, and hospitalization costs.

RESULTS

A total of 94 patients with 26 (27.66%) VV ECMO and 68 (72.34%) VA ECMO were enrolled. Compared to the VA ECMO patients, VV ECMO patients displayed a significantly lower in-hospital mortality (50 vs. 26.92%, p = 0.044) and proportion of neurologic complications, shorter duration of ECMO and MV, but the rate of successfully weaned from ECMO, bleeding, bloodstream infection complications and pump failure were similar. By contrast, oxygenator failure was more frequent in patients receiving VV ECMO. No significant intergroup difference was observed for the hospitalization costs.

CONCLUSION

These positive findings showed the conferred survival advantage and safety of VV ECMO compared with VA ECMO, suggesting that VV ECMO may be an effective initial treatment for patients with infection-associated severe PARDS.

The Association Between Alveolar Dead Space Fraction and Mortality in Pediatric Acute Respiratory Distress Syndrome: A Prospective Cohort Study

BACKGROUND

Alveolar dead-space fraction (AVDSF), the volume of alveolar gas that does not participate in gas exchange, has been reported to predict mortality and morbidity in adults with acute respiratory distress syndrome (ARDS). This study aims to characterize AVDSF in patients with pediatric ARDS (PARDS), to determine its association with clinical outcomes and examine the validity of a previously studied cutoff (AVDSF > 0.25).

METHODS

This was a prospective cohort study performed in the setting of a lung protective mechanical ventilation protocol. AVDSF was calculated by the equation: AVDSF = [partial pressure of arterial carbon dioxide (P_aCO₂) - end tidal carbon dioxide (etCO₂)]/P_aCO₂. Receiver operating curve and Youden index were used to identify an AVDSF cutoff associated with mortality, which characterized "high or low AVDSF" groups. Correlation between AVDSF and clinical indices of severity were determined [including daily oxygenation index (OI), admission Pediatric Index of Mortality 2 (PIM 2) and Pediatric Logistic Organ Dysfunction (PELOD) scores]. The primary outcome, mortality in PARDS patients, was compared between the high and low AVDSF groups and analyzed in a multivariable logistic regression adjusting for inotrope use and PIM 2 score. Secondary outcomes included 28-day ventilator-free (VFD) and intensive care unit-free (IFD) days.

RESULTS

Sixty-nine PARDS patients with a median (interquartile range) age of 4.5 (0.8, 10.6) years were included in this analysis. Daily AVDSF correlated with daily OI (R ² = 0.10; p < 0.001). Mean AVDSF over the first 7 days of PARDS correlated with PIM 2 (R ² = 0.10; p = 0.010) and PELOD (R ² = 0.12; p = 0.004) scores. The greatest area under the curve identified an AVDSF cutoff of 0.22, which was close to the previously suggested 0.25. The high AVDSF group had higher mortality [7/19 (36.8%) vs. 5/50 (10.0%); p = 0.009] and lower VFD [2 (0, 18) vs. 21 (15, 24); p = 0.007] and IFD [0 (0, 16) vs. 16 (5, 21); p = 0.013]. In the multivariable model, being in the high AVDSF group [adjusted odds ratio 4.67 (95% CI: 1.12, 19.39)] was significantly associated with mortality.

CONCLUSIONS

High AVDSF was independently associated with increased mortality and decreased VFD and IFD. AVDSF may be complementary to oxygenation indices in risk stratifying PARDS and warrant further study.

Performance of acute respiratory distress syndrome definitions in a high acuity paediatric intensive care unit

BACKGROUND

For years, paediatric critical care practitioners used the adult American European Consensus Conference (AECC) and revised Berlin Definition (BD) for acute respiratory distress syndrome (ARDS) to study the epidemiology of paediatric ARDS (PARDS). In 2015, the paediatric specific definition, Paediatric Acute Lung Injury Consensus Conference (PALICC) was developed. The use of non-invasive metrics of oxygenation to stratify disease severity were introduced in this definition, although this potentially may lead to a confounding effect of disease severity since it is more common to place indwelling arterial lines in sicker patients. We tested the hypothesis that PALICC outperforms AECC/BD in our high acuity PICU, which employs a liberal use of indwelling arterial lines and high-frequency oscillatory ventilation (HFOV).

METHODS

We retrospectively collected data from children < 18 years mechanically ventilated for at least 24 h in our tertiary care, university-affiliated paediatric intensive care unit. The primary endpoint was the difference in the number of PARDS cases between AECC/BD and PALICC. Secondary endpoints included mortality and ventilator free days. Performance was assessed by the area under the receiver operating characteristics curve (AUC-ROC).

RESULTS

Data from 909 out of 2433 patients was eligible for analysis. AECC/BD identified 35 (1.4%) patients (mortality 25.7%), whereas PALICC identified 135 (5.5%) patients (mortality 14.1%). All but two patients meeting AECC/Berlin criteria were also identified by PALICC. Almost half of the cohort (45.2%) had mild, 33.3% moderate and 21.5% severe PALICC PARDS at onset. Highest mortality rates were seen in patients with AECC acute lung injury (ALI)/mild Berlin and severe PALICC PARDS. The AUC-ROC for Berlin was the highest 24 h (0.392 [0.124-0.659]) after onset. PALICC showed the highest AUC-ROC at the same moment however higher than Berlin (0.531 [0.345-0.716]). Mortality rates were significantly increased in patients with bilateral consolidations (9.3% unilateral vs 26.3% bilateral, p = 0.025).

CONCLUSIONS

PALICC identified more new cases PARDS than the AECC/Berlin definition. However, both PALICC and Berlin performed poorly in terms of mortality risk stratification. The presence of bilateral consolidations was associated with a higher mortality rate. Our findings may be considered in future modifications of the PALICC criteria.

Pediatric ECMO Candidates at Non-ECMO Centers: Transfer, Cannulate, or Treat Locally?

Pediatric inpatient and intensive care specialists working outside of tertiary medical centers confront difficult clinical scenarios related to how best to care for extremely ill children who may or may not benefit from advanced medical technology, and these clinicians are often faced with limited local availability. Extracorporeal membrane oxygenation (ECMO) is a technology that is only available at a subset of tertiary care centers, and the decision to risk the transfer of a child for the potential benefit of ECMO is challenging. This article is aimed at addressing the main factors and ethical principles related to this decision-making: (1) whether ECMO is the standard of care, (2) clinical decision analysis of the risks and benefits, (3) informed consent and education of the parents and/or guardians, and (4) institutional leadership decision-making. A decisional framework is proposed that incorporates a thoughtful shared decision-making algorithm.

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.

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.

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.

Strain-specific differences in lung tissue viscoelasticity of mechanically ventilated infant Sprague-Dawley and Wistar rats

Rats are often used in ventilator-induced lung injury (VILI) models. However, strain-specific susceptibility for VILI has not been elucidated yet. The aim of this study was to demonstrate strain-specific differences in VILI in infant Sprague-Dawley and Wistar rats. VILI was compared in 2-wk-old pups after 8 h of protective or injurious ventilation. Pups were ventilated with tidal volumes (V_T) of ∼7 mL/kg and positive end-expiratory pressures (PEEP) of 6 cmH₂O (V_T7 PEEP6) or with V_T of ∼21 mL/kg and PEEP 2 cmH₂O (V_T21 PEEP2). Interleukin-6, macrophage inflammatory protein-2 (MIP-2), inflammatory cells, and albumin in bronchoalveolar lavage fluid (BALF); histology; and low-frequency forced oscillation technique (LFOT) and pressure-volume (PV) maneuvers were assessed. Alveolar macrophages, neutrophils, and MIP-2 derived from BALF revealed more pronounced VILI after V_T21 PEEP2 in both strains. LFOT and PV analyses demonstrated rat strain-specific differences both at baseline and particularly in response to V_T21 PEEP2 ventilation. Sprague-Dawley rats showed higher airway and tissue resistance and elastance values with no difference in hysteresivity between ventilation strategies. Wister rats challenged by V_T21 PEEP2 experienced significantly more energy dissipation when compared with V_T7 PEEP6 ventilation. In conclusion, both rat strains are useful for VILI models. The degree of VILI severity depends on ventilation strategy and selected strain. However, fundamental and time-dependent differences in respiratory system mechanics exist and reflect different lung tissue viscoelasticity. Hence, strain-specific characteristics of the respiratory system need to be considered when planning and interpreting VILI studies with infant rats.

Ultrasound cardiac output monitoring in mechanically ventilated children

AIM

To non-invasively identify the hemodynamic changes in critically ill children during the first 48 h following initiation of mechanical ventilation by the ultrasound cardiac output monitor (USCOM) method and compare the data in children with pulmonary and non-pulmonary pathology.

MATERIALS AND METHODS

This was a prospective observational study to evaluate the influence of mechanical ventilation on hemodynamic changes and to describe hemodynamic profiles of mechanically ventilated children. A total of 56 children with respiratory failure were included in the present study. Ventilated patients are divided into two groups. Group A (n=36) includes patients with pulmonary pathology. Group B (n=20) consists of patients with extra pulmonary etiology of respiratory failure. Hemodynamic parameters (cardiac index and systemic vascular resistance index) were evaluated using ultrasound cardiac output monitoring (USCOM 1A) immediately following initiation of mechanical ventilation and again at 6, 12, and 48 h. Pharmacological circulatory support (inotropes, vasopressors, levosimendan and phosphodiesterase III inhibitors) was individually and continuously modified based on real-time hemodynamic parameters and optimal fluid balance.

RESULTS

No significant differences in hemodynamic profiles were found between Group A and Group B.

CONCLUSION

The protective strategy of mechanical ventilation was not associated with significant differences in hemodynamic profiles between children ventilated for pulmonary and non-pulmonary pathologies.

CLINICAL SIGNIFICANCE

Hemodynamically unstable children ventilated for pulmonary pathology with the protective strategy of mechanical ventilation had a greater requirement for inotropic and combined inotropic and vasoactive circulatory support than children ventilated for non-pulmonary causes of respiratory failure.

Energy transmission in mechanically ventilated children: a translational study

Background

Recurrent delivery of tidal mechanical energy (ME) inflicts ventilator-induced lung injury (VILI) when stress and strain exceed the limits of tissue tolerance. Mechanical power (MP) is the mathematical description of the ME delivered to the respiratory system over time. It is unknown how ME relates to underlying lung pathology and outcome in mechanically ventilated children. We therefore tested the hypothesis that ME per breath with tidal volume (Vt) normalized to bodyweight correlates with underlying lung pathology and to study the effect of resistance on the ME dissipated to the lung.

Methods

We analyzed routinely collected demographic, physiological, and laboratory data from deeply sedated and/or paralyzed children < 18 years with and without lung injury. Patients were stratified into respiratory system mechanic subgroups according to the Pediatric Mechanical Ventilation Consensus Conference (PEMVECC) definition. The association between MP, ME, lung pathology, and duration of mechanical ventilation as a primary outcome measure was analyzed adjusting for confounding variables and effect modifiers. The effect of endotracheal tube diameter (ETT) and airway resistance on energy dissipation to the lung was analyzed in a bench model with different lung compliance settings.

Results

Data of 312 patients with a median age of 7.8 (1.7–44.2) months was analyzed. Age (p <  0.001), RR p <  0.001), and Vt <  0.001) were independently associated with MPrs. ME but not MP correlated significantly (p <  0.001) better with lung pathology. Competing risk regression analysis adjusting for PRISM III 24 h score and PEMVECC stratification showed that ME on day 1 or day 2 of MV but not MP was independently associated with the duration of mechanical ventilation. About 33% of all energy generated by the ventilator was transferred to the lung and highly dependent on lung compliance and airway resistance but not on endotracheal tube size (ETT) during pressure control (PC) ventilation.

Conclusions

ME better related to underlying lung pathology and patient outcome than MP. The delivery of generated energy to the lung was not dependent on ETT size during PC ventilation. Further studies are needed to identify injurious MErs thresholds in ventilated children.

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.

Clinical Course of Pediatric Acute Respiratory Distress Syndrome at Moderate Altitude

Background

This is a retrospective case series, and the main objective is to describe the epidemiology, clinical features, and outcomes of pediatric acute respiratory distress syndrome in patients at moderate altitude.

Methods

Children from the Pediatric Intensive Care Unit (PICU) at the Fundación Cardioinfantil, hospitalized with acute respiratory distress syndrome, were prospectively enrolled from March 2009 to March 2014. We evaluated the demographic data, mechanical ventilation, gas exchange, hemodynamics, and multiorgan dysfunction.

Results

During the study period, 88 patients met the inclusion criteria. Bronchiolitis and pneumonia were the most common causes of acute respiratory distress syndrome. The overall mortality rate was 19.5%. At the beginning of the study, the average relation between blood pressure and the fraction of inspired oxygen (Pa/Fi) was 130.3 ± 52.2; tidal volume was 7.94 ± 1.7 ml/kg, the plateau pressure 25.3 ± 5.09 cmH₂O, and positive end-expiratory pressure was 7.2 ± 3.2 cmH₂O. After 24 hours, the mortality rate in the group with severe acute respiratory distress syndrome (Pa/Fi <100) was 46.7%, in the moderate acute respiratory distress syndrome group (Pa/Fi 100-200) it was 11.9%, and finally in the mild acute respiratory distress syndrome group (Pa/Fi 200-300) the mortality was 25%. This study found a relation between serum lactate value and positive end-expiratory pressure and mortality (p = 0.02 and 0.0013).

Conclusions

This study shows that pediatric acute respiratory distress syndrome patients at moderate altitudes have similar clinical behavior, including mortality rate, to those at low altitudes. However, Pa/Fi is not a good predictor of mortality for patients with mild and moderate acute respiratory distress syndrome.

Early Use of Adjunctive Therapies for Pediatric Acute Respiratory Distress Syndrome: A PARDIE Study

Rationale: Few data exist to guide early adjunctive therapy use in pediatric acute respiratory distress syndrome (PARDS).Objectives: To describe contemporary use of adjunctive therapies for early PARDS as a framework for future investigations.Methods: This was a preplanned substudy of a prospective, international, cross-sectional observational study of children with PARDS from 100 centers over 10 study weeks.Measurements and Main Results: We investigated six adjunctive therapies for PARDS: continuous neuromuscular blockade, corticosteroids, inhaled nitric oxide (iNO), prone positioning, high-frequency oscillatory ventilation (HFOV), and extracorporeal membrane oxygenation. Almost half (45%) of children with PARDS received at least one therapy. Variability was noted in the median starting oxygenation index of each therapy; corticosteroids started at the lowest oxygenation index (13.0; interquartile range, 7.6-22.0) and HFOV at the highest (25.7; interquartile range, 16.7-37.3). Continuous neuromuscular blockade was the most common, used in 31%, followed by iNO (13%), corticosteroids (10%), prone positioning (10%), HFOV (9%), and extracorporeal membrane oxygenation (3%). Steroids, iNO, and HFOV were associated with comorbidities. Prone positioning and HFOV were more common in middle-income countries and less frequently used in North America. The use of multiple ancillary therapies increased over the first 3 days of PARDS, but there was not an easily identifiable pattern of combination or order of use.Conclusions: The contemporary description of prevalence, combinations of therapies, and oxygenation threshold for which the therapies are applied is important for design of future studies. Region of the world, income, and comorbidities influence adjunctive therapy use and are important variables to include in PARDS investigations.

Impact of high tidal volume ventilation on surfactant metabolism and lung injury in infant rats

The poorly understood tolerance toward high tidal volume (V_T) ventilation observed in critically ill children and age-equivalent animal models may be explained by surfactant homeostasis. The aim of our prospective animal study was to test whether high V_T with adequate positive end-expiratory pressure (PEEP) is associated with surfactant de novo synthesis and secretion, leading to improved lung function, and whether extreme mechanical ventilation affects intracellular lamellar body formation and exocytosis. Rats (14 days old) were allocated to five groups: nonventilated controls, PEEP 5 cmH₂O with V_T of 8, 16, and 24 mL/kg, and PEEP 1 cmH₂O with V_T 24 mL/kg. Following 6 h of ventilation, lung function, surfactant proteins and phospholipids, and lamellar bodies were assessed by forced oscillation technique, quantitative real-time polymerase chain reaction, mass spectrometry, immunohistochemistry, and transmission electron microscopy. High V_T (24 mL/kg) with PEEP of 5 cmH₂O improved respiratory system mechanics and was not associated with lung injury, elevated surfactant protein expression, or surfactant phospholipid content. Extreme ventilation with V_T 24 mL/kg and PEEP 1 cmH₂O produced a mild inflammatory response and correlated with higher surfactant phospholipid concentrations in bronchoalveolar lavage fluid without affecting lamellar body count and morphology. Elevated phospholipid concentrations in the potentially most injurious strategy (V_T 24 mL/kg, PEEP 1 cmH₂O) need further evaluation and might reflect accumulation of biophysically inactive small aggregates. In conclusion, our data confirm the resilience of infant rats toward high V_T-induced lung injury and challenge the relevance of surfactant synthesis, storage, and secretion as protective factors.

Association between age and acute respiratory distress syndrome development and mortality following trauma

BACKGROUND

Improved understanding of the relationship between patient age and acute respiratory distress syndrome (ARDS) development and mortality following traumatic injury may help facilitate generation of new hypotheses about ARDS pathophysiology and the role of novel treatments to improve outcomes across the age spectrum.

METHODS

We conducted a retrospective cohort study of trauma patients included in the National Trauma Data Bank who were admitted to an intensive care unit from 2007 to 2016. We determined ARDS incidence and mortality across eight age groups for the entire 10-year study period and by year. We used generalized linear Poisson regression models adjusted for underlying mortality risk (injury mechanism, Injury Severity Score, admission Glasgow Coma Scale score, admission heart rate, and admission hypotension).

RESULTS

Acute respiratory distress syndrome occurred in 3.1% of 1,297,190 trauma encounters. Acute respiratory distress syndrome incidence was lowest among pediatric patients and highest among adults aged 35 to 64 years. Acute respiratory distress syndrome mortality was highest among patients 80 years or older (43.9%), followed by 65 to 79 years (30.6%) and 4 years or younger (25.3%). The relative risk of mortality associated with ARDS was highest among the pediatric age groups, with an adjusted relative risk (aRR) of 2.06 (95% confidence interval [CI], 1.72-2.70) among patients 4 years or younger compared with an aRR of 1.51 (95% CI, 1.42-1.62) for the entire cohort. Acute respiratory distress syndrome mortality increased over the 10-year study period (aRR, 1.03 per year; 95% CI, 1.02-1.05 per year), whereas all-cause mortality decreased (aRR, 0.98 per year; 95% CI, 0.98-0.99 per year).

CONCLUSIONS

While ARDS development following traumatic injury was most common in middle-aged adults, patients 4 years or younger and 65 years or older with ARDS experienced the highest burden of mortality. Children 4 years or younger were disproportionately affected by ARDS relative to their low underlying mortality following trauma that was not complicated by ARDS. Acute respiratory distress syndrome-associated mortality following trauma has worsened over the past decade, emphasizing the need for new prevention and treatment strategies.

LEVEL OF EVIDENCE

Prognostic/epidemiological study, level III.

Extracorporeal Membrane Oxygenation for Severe Respiratory Failure During Respiratory Epidemics and Pandemics: A Narrative Review

Introduction: Epidemics and pandemics from zoonotic respiratory viruses, such as the 2019 novel coronavirus, can lead to significant global intensive care burden as patients progress to acute respiratory distress syndrome (ARDS). A subset of these patients develops refractory hypoxaemia despite maximal conventional mechanical ventilation and require extracorporeal membrane oxygenation (ECMO). This review focuses on considerations for ventilatory strategies, infection control and patient selection related to ECMO for ARDS in a pandemic. We also summarise the experiences with ECMO in previous respiratory pandemics. Materials and Methods: A review of pertinent studies was conducted via a search using MEDLINE, EMBASE and Google Scholar. References of articles were also examined to identify other relevant publications. Results: Since the H1N1 Influenza pandemic in 2009, the use of ECMO for ARDS continues to grow despite limitations in evidence for survival benefit. There is emerging evidence to suggest that lung protective ventilation for ARDS can be further optimised while receiving ECMO so as to minimise ventilator-induced lung injury and subsequent contributions to multi-organ failure. Efforts to improve outcomes should also encompass appropriate infection control measures to reduce co-infections and prevent nosocomial transmission of novel respiratory viruses. Patient selection for ECMO in a pandemic can be challenging. We discuss important ethical considerations and predictive scoring systems that may assist clinical decision-making to optimise resource allocation. Conclusion: The role of ECMO in managing ARDS during respiratory pandemics continues to grow. This is supported by efforts to redefine optimal ventilatory strategies, reinforce infection control measures and enhance patient selection. Ann Acad Med Singapore 2020;49:199–214 Key words: Acute Respiratory Distress Syndrome, Coronavirus disease 2019, ECMO, Infection control, Mechanical ventilation

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.

Morbidity and Mortality Among Critically Injured Children With Acute Respiratory Distress Syndrome

OBJECTIVES

To evaluate morbidity and mortality among critically injured children with acute respiratory distress syndrome.

DESIGN

Retrospective cohort study.

SETTING

Four-hundred sixty Level I/II adult or pediatric trauma centers contributing to the National Trauma Data Bank.

PATIENTS

One hundred forty-six thousand fifty-eight patients less than 18 years old admitted to an ICU with traumatic injury from 2007 to 2016.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We assessed in-hospital mortality and need for postdischarge care among patients with and without acute respiratory distress syndrome and hospital resource utilization and discharge disposition among survivors. Analyses were adjusted for underlying mortality risk (age, Injury Severity Score, serious brain or chest injury, and admission heart rate and hypotension) and year, transfer status, and facility trauma level designation. Acute respiratory distress syndrome occurred in 2,590 patients (1.8%). Mortality was 20.0% among acute respiratory distress syndrome patients versus 4.3% among nonacute respiratory distress syndrome patients, with an adjusted relative risk of 1.76 (95% CI, 1.52-2.04). Postdischarge care was required in an additional 44.8% of acute respiratory distress syndrome patients versus 16.0% of patients without acute respiratory distress syndrome (adjusted relative risk, 3.59; 2.87-4.49), with only 35.1% of acute respiratory distress syndrome patients discharging to home versus 79.8% of patients without acute respiratory distress syndrome. Acute respiratory distress syndrome mortality did not change over the 10-year study period (adjusted relative risk, 1.01/yr; 0.96-1.06) nor did the proportion of acute respiratory distress syndrome patients requiring postdischarge care (adjusted relative risk, 1.04/yr; 0.97-1.11). Duration of ventilation, ICU stay, and hospital stay were all significantly longer among acute respiratory distress syndrome survivors. Tracheostomy placement occurred in 18.4% of acute respiratory distress syndrome survivors versus 2.1% of patients without acute respiratory distress syndrome (adjusted relative risk, 3.10; 2.59-3.70).

CONCLUSIONS

Acute respiratory distress syndrome development following traumatic injury in children is associated with significantly increased risk of morbidity and mortality, even after adjustment for injury severity and hemodynamic abnormalities. Outcomes have not improved over the past decade, emphasizing the need for new therapeutic interventions, and prevention strategies for acute respiratory distress syndrome among severely injured children.

Mitochondrial transplantation enhances murine lung viability and recovery after ischemia-reperfusion injury

The most common cause of acute lung injury is ischemia-reperfusion injury (IRI), during which mitochondrial damage occurs. We have previously demonstrated that mitochondrial transplantation is an efficacious therapy to replace or augment mitochondria damaged by IRI, allowing for enhanced muscle viability and function in cardiac tissue. Here, we investigate the efficacy of mitochondrial transplantation in a murine lung IRI model using male C57BL/6J mice. Transient ischemia was induced by applying a microvascular clamp on the left hilum for 2 h. Upon reperfusion mice received either vehicle or vehicle-containing mitochondria either by vascular delivery (Mito V) through the pulmonary artery or by aerosol delivery (Mito Neb) via the trachea (nebulization). Sham control mice underwent thoracotomy without hilar clamping and were ventilated for 2 h before returning to the cage. After 24 h recovery, lung mechanics were assessed and lungs were collected for analysis. Our results demonstrated that at 24 h of reperfusion, dynamic compliance and inspiratory capacity were significantly increased and resistance, tissue damping, elastance, and peak inspiratory pressure (Mito V only) were significantly decreased (P < 0.05) in Mito groups as compared with their respective vehicle groups. Neutrophil infiltration, interstitial edema, and apoptosis were significantly decreased (P < 0.05) in Mito groups as compared with vehicles. No significant differences in cytokines and chemokines between groups were shown. All lung mechanics results in Mito groups except peak inspiratory pressure in Mito Neb showed no significant differences (P > 0.05) as compared with Sham. These results conclude that mitochondrial transplantation by vascular delivery or nebulization improves lung mechanics and decreases lung tissue injury.

Ventilator-induced lung injury in children: a reality?

Mechanical ventilation (MV) is inextricably linked to the care of critically ill patients admitted to the paediatric intensive care unit (PICU). Even today, little evidence supports best MV practices for life-threatening acute respiratory failure in children. However, careful attention must be paid because this life-saving technique induces pulmonary inflammation that aggravates pre-existing lung injury, a concept that is known as ventilator-induced lung injury (VILI). The delivery of too large tidal volumes (Vt) (i.e., volutrauma) and repetitive opening and closure of alveoli (i.e., atelectrauma) are two key mechanisms underlying VILI. Despite the knowledge of these mechanisms, the clinical relevance of VILI in critically ill children is poorly understood as almost all of our knowledge has been obtained from studies in adults or experimental studies mimicking the adult critical care situation. This leaves the question if VILI is relevant in the paediatric context. In fact, limited paediatric experimental data showed that the use of large, supraphysiologic Vt resulted in less inflammation and injury in paediatric animal models compared to adult models. Furthermore, the association between large Vt and adverse outcome has not been confirmed and the issue of setting positive end-expiratory pressure (PEEP) to prevent atelectrauma has hardly been studied in paediatric clinical studies. Hence, even today, the question whether or not there VILI is relevant in pediatric critical remains to be answered. Consequently, how MV is used remains thus based on institutional preferences, personal beliefs and clinical data extrapolated from adults. This signifies the need for clinical and experimental studies in order to better understand the use and effects of MV in paediatric patients with or without lung injury.

Steroids in pediatric acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a complex entity with high potential for harm and healthcare resource utilization. Despite multiple clinical advances in its ventilatory management, ARDS continues to be one of the most challenging disease processes for intensivists. It continues to lack a direct, proven and desperately needed effective therapeutic intervention. Given their biologic rationale, corticosteroids have been widely used by clinicians and considered useful by many in the management of ARDS since its first description. Adult data is abundant, yet contradictory. Controversy remains regarding the routine use of corticosteroids in ARDS. Therefore, widespread evidence-based recommendations for this heterogeneous disease process have not been made. In this article, our aim was to provide a summary of available evidence for the role of steroids in the treatment of ARDS, while giving special focus on pediatric ARDS (PARDS).

What do we know about optimal nutritional strategies in children with pediatric acute respiratory distress syndrome?

Nutrition in pediatric acute respiratory distress syndrome (PARDS) is an essential aspect of therapy, with potential to modify outcomes. The gut is slowly establishing its place as the motor of critical illness, and the 'gut-lung' axis has been shown to be in play in the systemic inflammatory response. Thus, utilizing the gut to modify outcomes in PARDS is an exciting prospect. PARDS is associated with high mortality in low- and middle-income countries (LMIC), where malnutrition is also prevalent and may worsen during hospital stay. Mortality may be higher in this subgroup of patients. At present, the gold standard to estimate resting energy expenditure (REE) in critically ill children is indirect calorimetry. However, it is a cumbersome and expensive procedure, as a result of which its routine practice is limited to very few units across the world. Therefore, predictive equations, which may under- or over-estimate REE, are relied upon to approximate calorie and protein needs of children with PARDS. Despite having target calorie and protein requirements, studies have found that a large proportion of critically ill children do not achieve these levels even at the end of a week in pediatric intensive care unit (PICU). The preferred mode of nutrition delivery is enteral, and if possible, early enteral nutrition (EEN). Immunonutrition has been a lucrative subject of research, and while there have been some strides, no therapy has yet conclusively demonstrated benefit in terms of mortality or reduced length of stay in PICU or the hospital. Probable immunonutrients in PARDS include omega-3 fatty acids, arginine, glutamine and vitamin D, though none are a part of any recommendations yet.

Extra-corporeal membrane oxygenation in paediatric acute respiratory distress syndrome: overrated or underutilized?

Extracorporeal membrane oxygenation (ECMO) is a modified form of cardiopulmonary bypass which may provide support for severe cardiorespiratory failure including paediatric acute respiratory distress syndrome (PARDS). While ECMO was initially demonstrated to successfully support neonates with severe respiratory failure, the use of ECMO has expanded rapidly to support both paediatric and adult respiratory failure. Extracorporeal Life Support Organization (ELSO) registry data shows that the use of ECMO for paediatric respiratory failure has expanded rapidly over the past decades with increasing use of venovenous ECMO. Despite the increasing complexity of children supported by ECMO for ARDS, outcomes have remained consistent with survival to hospital discharge greater than 50%. ECMO complications are still common and potentially devastating, especially neurological complications. There is grade 1 evidence to support the use of ECMO in both neonatal and adult respiratory failure but evidence in paediatric respiratory failure is confined to case series and case-control studies. While there are no published guidelines for use of ECMO in PARDS, in particular no clearly defined inclusion and exclusion criteria, current evidence suggests that children with severe ARDS may benefit from ECMO support, with survival to hospital discharge equivalent or better than conventional management in children with severe ARDS.

Definition and global epidemiology of pediatric acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) has been known to occur in children since early descriptions of the disease, but pediatric specific diagnostic criteria were first established in 2015 with the Pediatric Acute Lung Injury Consensus Conference (PALICC) definition of pediatric ARDS (PARDS). There were substantial changes proposed with the PALICC definition, including simplification of radiographic criteria, use of pulse oximetry based metrics to define PARDS, specific criteria for non-invasive ventilation, and the use of oxygenation index (OI) instead of PaO2/FiO2 ratio for those on invasive ventilation. While these changes could potentially result in major changes in the reported incidence and outcome of PARDS, review of the recent literature since publication of the PALICC definitions highlight that major elements regarding the contemporary epidemiology of PARDS have remained stable over the past 20 years. This highlights that the PARDS definition is likely catching up to changes in clinical practice, and suggests that this new definition should be used moving forward as it is more reflective of current practice than historical definitions. However, it is also clear that PARDS severity alone (as measured by the PALICC) criteria insufficiently characterizes the risk for mortality or other important clinical outcomes amongst PARDS patients, although there appears to be some association between PARDS severity and outcome, particularly when hypoxemia is severe.

Risk Factors on Hospital Arrival for Acute Respiratory Distress Syndrome Following Pediatric Trauma

OBJECTIVES

To determine risk factors identifiable at hospital arrival associated with acute respiratory distress syndrome development among critically injured children.

DESIGN

Retrospective cohort study.

SETTING

Level I or II adult or pediatric trauma centers contributing to the National Trauma Data Bank from 2007 to 2016.

PATIENTS

Patients less than 18 years admitted to an ICU with traumatic injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We determined associations between patient, injury, and clinical characteristics present at hospital arrival with development of acute respiratory distress syndrome recorded as a hospital complication. Acute respiratory distress syndrome occurred in 1.8% of 146,058 critically injured children (n = 2,590). The only demographic factor associated with higher risk of developing acute respiratory distress syndrome on multivariable analysis was African American race (relative risk, 1.42 vs white; 95% CI, 1.13-1.78). Injury characteristics included firearm injuries (relative risk 1.93; 1.50-2.48) and motor vehicle crashes (relative risk, 1.91; 1.57-2.31) relative to falls; spine (relative risk, 1.39; 1.20-1.60), chest (relative risk, 1.36; 1.22-1.52), or lower extremity injuries (relative risk, 1.26; 1.10-1.44); amputations (relative risk, 2.10; 1.51-2.91); and more severe injury (relative risk, 3.69 for Injury Severity Score 40-75 vs 1-8; 2.50-5.44). Clinical variables included abnormal respiratory status (intubated relative risk, 1.67; 1.23-2.26 and hypopnea relative risk, 1.23; 1.05-1.45 and tachypnea relative risk, 1.26; 1.10-1.44) and lower Glasgow Coma Scale score (relative risk, 5.61 for Glasgow Coma Scale score 3 vs 15; 4.44-7.07).

CONCLUSIONS

We provide the first description of the incidence of and risk factors for acute respiratory distress syndrome among pediatric trauma patients. Improved understanding of the risk factors associated with acute respiratory distress syndrome following pediatric trauma may help providers anticipate its development and intervene early to improve outcomes for severely injured children.

Early Right Ventricular Systolic Dysfunction and Pulmonary Hypertension Are Associated With Worse Outcomes in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

The prevalence and importance of early right ventricular dysfunction and pulmonary hypertension in pediatric acute respiratory distress syndrome are unknown. We aimed to describe the prevalence of right ventricular dysfunction and pulmonary hypertension within 24 hours of pediatric acute respiratory distress syndrome diagnosis and their associations with outcomes.

DESIGN

Retrospective, single-center cohort study.

SETTING

Tertiary care, university-affiliated PICU.

PATIENTS

Children who had echocardiograms performed within 24 hours of pediatric acute respiratory distress syndrome diagnosis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Between July 1, 2012, and June 30, 2016, 103 children met inclusion criteria. Echocardiograms were analyzed using established indices of right ventricular and left ventricular systolic function and for evidence of pulmonary hypertension. Echocardiographic abnormalities were common: 26% had low right ventricular fractional area change, 65% had low tricuspid annular plane systolic excursion, 30% had low left ventricular fractional shortening, and 21% had evidence of pulmonary hypertension. Abnormal right ventricular global longitudinal strain and abnormal right ventricular free wall strain were present in 35% and 40% of patients, respectively. No echocardiographic variables differed between or across pediatric acute respiratory distress syndrome severity. In multivariable analyses, right ventricular global longitudinal strain was independently associated with PICU mortality (odds ratio, 3.57 [1.33-9.60]; p = 0.01), whereas right ventricular global longitudinal strain, right ventricular free wall strain, and the presence of pulmonary hypertension were independently associated with lower probability of extubation (subdistribution hazard ratio, 0.46 [0.26-0.83], p = 0.01; subdistribution hazard ratio, 0.58 [0.35-0.98], p = 0.04; and subdistribution hazard ratio, 0.49 [0.26-0.92], p = 0.03, respectively).

CONCLUSIONS

Early ventricular dysfunction and pulmonary hypertension were detectable, prevalent, and independent of lung injury severity in children with pediatric acute respiratory distress syndrome. Right ventricular dysfunction was associated with PICU mortality, whereas right ventricular dysfunction and pulmonary hypertension were associated with lower probability of extubation.

Epidemiology of Cause of Death in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

Investigations of acute respiratory distress syndrome in adults suggest hypoxemia is an uncommon cause of death. However, the epidemiology of death in pediatric acute respiratory distress syndrome is not well characterized. We aimed to describe the cause, mode, and timing of death in pediatric acute respiratory distress syndrome nonsurvivors. We hypothesized that most deaths would be due to nonpulmonary factors, rather than hypoxemia.

DESIGN

Retrospective, decedent-only analysis.

SETTING

Two large, academic PICUs.

PATIENTS

Nonsurvivors with pediatric acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 798 subjects with pediatric acute respiratory distress syndrome, there were 153 nonsurvivors (19% mortality). Median time to death was 6 days (interquartile range, 3-13 d) after pediatric acute respiratory distress syndrome onset. Patients dying less than 7 days after pediatric acute respiratory distress syndrome onset had greater illness severity and worse oxygenation. Patients dying less than 7 days were more likely to die of a neurologic cause, including brain death. Patients dying greater than or equal to 7 days after pediatric acute respiratory distress syndrome onset were more commonly immunocompromised. Multisystem organ failure predominated in deaths greater than or equal to 7 days. Withdrawal of therapy was the most common mode of death at all timepoints, accounting for 66% of all deaths. Organ dysfunction was common at time of death, irrespective of cause of death. Refractory hypoxemia accounted for only a minority of pediatric acute respiratory distress syndrome deaths (20%).

CONCLUSIONS

In pediatric acute respiratory distress syndrome, early deaths were due primarily to neurologic failure, whereas later deaths were more commonly due to multisystem organ failure. Deaths from neurologic causes accounted for a substantial portion of nonsurvivors. Refractory hypoxemia accounted for only a minority of deaths. Our study highlights limitations associated with using death as an endpoint in therapeutic pediatric acute respiratory distress syndrome trials.

Acute respiratory failure and the kinetics of neutrophil recovery in pediatric hematopoietic cell transplantation: a multicenter study

In this multicenter study, we investigated the kinetics of neutrophil recovery in relation to acuity and survival among 125 children undergoing allogeneic hematopoietic cell transplantation (allo-HCT) who required invasive mechanical ventilation (IMV). Recovery of neutrophils, whether prior to or after initiation of IMV, was associated with a significantly decreased risk of death relative to never achieving neutrophil recovery. A transient increase in acuity (by oxygenation index and vasopressor requirements) occurred among a subset of the patients who achieved neutrophil recovery after initiation of IMV; 61.5% of these patients survived to discharge from the intensive care unit (ICU). Improved survival among patients who subsequently achieved neutrophil recovery on IMV was not limited to those with peri-engraftment respiratory distress syndrome. The presence of a respiratory pathogen did not affect the risk of death while on IMV but was associated with an increased length of IMV (p < 0.01). Among patients undergoing HCT who develop respiratory failure and require advanced therapeutic support, neutrophil recovery at time of IMV and/or presence of a respiratory pathogen should not be used as determining factors when counseling families about survival.

Plasma total fibroblast growth factor 23 levels are associated with acute kidney injury and mortality in children with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) has high rates of mortality and multisystem morbidity. Pre-clinical data suggest that fibroblast growth factor 23 (FGF23) may contribute to pulmonary pathology, and FGF23 is associated with mortality and morbidity, including acute kidney injury (AKI), in non-ARDS cohorts. Here, we assess whether FGF23 is associated with AKI and/or mortality in a cohort of 161 pediatric ARDS patients. Plasma total (intact + C-terminal) FGF23 and intact FGF23 concentrations were measured within 24 hours of ARDS diagnosis (Day 1), and associations with Day 3 AKI and 60-day mortality were evaluated. 35 patients (22%) developed AKI by 3 days post-ARDS diagnosis, and 25 (16%) died by 60 days post-ARDS diagnosis. In unadjusted models, higher Day 1 total FGF23 was associated with Day 3 AKI (odds ratio (OR) 2.22 [95% confidence interval (CI) 1.62, 3.03], p<0.001), but Day 1 intact FGF23 was not. In a model adjusted for demographics and disease severity, total FGF23 remained associated with AKI (OR 1.52 [95% CI 1.02, 2.26], p = 0.039). In unadjusted models, both higher Day 1 total and intact FGF23 were associated with 60-day mortality (OR 1.43 [95% CI 1.07, 1.91], p = 0.014; and OR 1.44 [95% CI 1.02, 2.05], p = 0.039, respectively). In the adjusted model, only total FGF23 remained associated with 60-day mortality (OR 1.62 [95% CI 1.07, 2.45], p = 0.023). In a subgroup analysis of patients with Day 1 plasma IL-6 concentrations available, inflammation partially mediated the association between total FGF23 and AKI. Our data suggest both inflammation-dependent and inflammation-independent associations between total FGF23 and clinical outcomes in pediatric ARDS patients.

In Vitro Characterization of the Pittsburgh Pediatric Ambulatory Lung

Acute and chronic respiratory failure are a significant source of pediatric morbidity and mortality. Current respiratory support options used to bridge children to lung recovery or transplantation typically render them bedridden and can worsen long-term patient outcomes. The Pittsburgh Pediatric Ambulatory Lung (P-PAL) is a wearable pediatric blood pump and oxygenator (0.3 m surface area) integrated into a single compact unit that enables patient ambulation. The P-PAL is intended for long-term use and designed to provide up to 90% of respiratory support in children weighing 5-25 kg. Computational fluid dynamics and numerical gas exchange modeling were used to design the P-PAL and predict its performance. A P-PAL prototype was then used to obtain pressure versus flow curves at various impeller rotation rates using a blood analog fluid. In vitro oxygen exchange rates were obtained in blood in accordance with ISO standard 7199. The normalized index of hemolysis (NIH) was measured over a 6 hour period at blood flow rates of 1 and 2.5 L/min. The P-PAL provided blood flows of 1-2.5 L/min against the pressure drop associated with its intended-use pediatric cannulas. The oxygen exchange rate reached a maximum of 108 ml/min at a blood flow rate of 2.5 L/min and met our respiratory support design target. Device-induced hemolysis was low with NIH values of 0.022-0.027 g/100 L in the intended blood flow rate range. In conclusion, the current P-PAL design met our pumping, oxygenation, and hemolysis specifications and has the potential to improve treatment for pediatric respiratory failure.

Risk Stratification Using Oxygenation in the First 24 Hours of Pediatric Acute Respiratory Distress Syndrome

OBJECTIVE

Oxygenation measured 24 hours after acute respiratory distress syndrome onset more accurately stratifies risk, relative to oxygenation at onset, in both children and adults. However, waiting 24 hours is problematic, especially for interventions that are more efficacious early in the disease course. We aimed to delineate whether oxygenation measured at timepoints earlier than 24 hours would retain predictive validity in pediatric acute respiratory distress syndrome.

DESIGN

Observational cohort study.

SETTING

Two large, academic PICUs.

PATIENTS

Invasively ventilated children with acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

PaO2/FIO2 and oxygenation index (mean airway pressure × FIO2 × 100)/PaO2) were measured at acute respiratory distress syndrome onset, at 6, 12, 18, and 24 hours after in 459 children at the Children's Hospital of Philadelphia. Neither PaO2/FIO2 nor oxygenation index at acute respiratory distress syndrome onset discriminated outcome. Between 6 and 24 hours, both PaO2/FIO2 (area under receiver operating curve for mortality between 0.57 and 0.62; p = 0.049-0.002) and oxygenation index (area under receiver operating curve, 0.60-0.62; p = 0.006-0.001) showed good discrimination and calibration across multiple outcomes, including mortality, ventilator-free days at 28 days, ventilator days in survivors, and probability of extubation, given competing risk of death. The utility of oxygenation at 12 hours was confirmed in an independent cohort from the Children's Hospital of Los Angeles.

CONCLUSION

Oxygenation measured between 6 and 12 hours of acute respiratory distress syndrome onset accurately stratified outcomes in children. Our results have critical implications for the design of trials, especially for interventions with greater impact in early acute respiratory distress syndrome.

Positive End-Expiratory Pressure Lower Than the ARDS Network Protocol Is Associated with Higher Pediatric Acute Respiratory Distress Syndrome Mortality

RATIONALE

The ARDS Network (ARDSNet) used a positive end-expiratory pressure (PEEP)/Fi_O2 model in many studies. In general, pediatric intensivists use less PEEP and higher Fi_O2 than this model.

OBJECTIVES

To evaluate whether children managed with PEEP lower than recommended by the ARDSNet PEEP/Fi_O2 model had higher mortality.

METHODS

This was a multicenter, retrospective analysis of patients with pediatric acute respiratory distress syndrome (PARDS) managed without a formal PEEP/Fi_O2 protocol. Four distinct datasets were combined for analysis. We extracted time-matched PEEP/Fi_O2 values, calculating the difference between PEEP level and the ARDSNet-recommended PEEP level for a given Fi_O2. We analyzed the median difference over the first 24 hours of PARDS diagnosis against ICU mortality and adjusted for confounding variables, effect modifiers, or factors that may have affected the propensity to use lower PEEP.

MEASUREMENTS AND MAIN RESULTS

Of the 1,134 patients with PARDS, 26.6% were managed with lower PEEP relative to the amount of Fi_O2 recommended by the ARDSNet protocol. Patients managed with lower PEEP experienced higher mortality than those who were managed with PEEP levels in line with or higher than recommended by the protocol (P < 0.001). After adjustment for hypoxemia, inotropes, comorbidities, severity of illness, ventilator settings, nitric oxide, and dataset, PEEP lower than recommended by the protocol remained independently associated with higher mortality (odds ratio, 2.05; 95% confidence interval, 1.32-3.17). Findings were similar after propensity-based covariate adjustment (odds ratio, 2.00; 95% confidence interval, 1.24-3.22).

CONCLUSIONS

Patients with PARDS managed with lower PEEP relative to Fi_O2 than recommended by the ARDSNet model had higher mortality. Clinical trials targeting PEEP management in PARDS are needed.

The Current State of Pediatric Acute Respiratory Distress Syndrome

Pediatric acute respiratory distress syndrome (PARDS) is a significant cause of morbidity and mortality in children. Children with PARDS often require intensive care admission and mechanical ventilation. Unfortunately, beyond lung protective ventilation, there are limited data to support our management strategies in PARDS. The Pediatric Acute Lung Injury Consensus Conference (PALICC) offered a new definition of PARDS in 2015 that has improved our understanding of the true epidemiology and heterogeneity of the disease as well as risk stratification. Further studies will be crucial to determine optimal management for varying disease severity. This review will present the physiologic basis of PARDS, describe the unique pediatric definition and risk stratification, and summarize the current evidence for current standards of care as well as adjunctive therapies.

Association Between Tidal Volumes Adjusted for Ideal Body Weight and Outcomes in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

The impact of tidal volume on outcomes in mechanically ventilated children with pediatric acute respiratory distress syndrome remains unclear. To date, observational investigations have failed to calculate tidal volume based on standardized corrections of weight. We investigated the impact of tidal volume on mortality and probability of extubation in pediatric acute respiratory distress syndrome using ideal body weight-adjusted tidal volume.

DESIGN

Retrospective analysis of an ongoing prospective cohort of pediatric acute respiratory distress syndrome patients. Tidal volume was calculated based on actual body weight and two different formulations of ideal body weight.

SETTING

PICU at a large, tertiary care children's hospital.

PATIENTS

Pediatric acute respiratory distress syndrome patients on conventional ventilation with a documented height or length.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 483 patients with a measured height or length at pediatric acute respiratory distress syndrome onset included in the final analysis, with 73 nonsurvivors (15%). At 24 hours, there remained 400 patients on conventional ventilation. When calculating tidal volume based on ideal body weight by either method, volumes were larger both at onset and at 24 hours compared with tidal volume based on actual body weight (all p < 0.001), and the proportion of patients being ventilated with tidal volumes greater than 10 mL/kg based on ideal body weight was larger both at onset (12.4% and 15.5%) and 24 hours (10.3% and 11.5%) compared with actual body weight at onset (3.5%) and 24 hours (4.0%) (all p < 0.001). Tidal volume, based on both actual body weight and ideal body weight, was not associated with either increased mortality or decreased probability of extubation after adjusting for oxygenation index in the whole cohort, whereas associations between higher tidal volume and poor outcomes were seen in subgroup analyses in overweight children and in severe pediatric acute respiratory distress syndrome.

CONCLUSIONS

Our retrospective analysis of a cohort of pediatric acute respiratory distress syndrome patients did not find a consistent association between tidal volume adjusted for ideal body weight and outcomes, although an association may exist in certain subgroups. Although it remains to be shown in a prospective trial whether high volumes or pressures are injurious in pediatric acute respiratory distress syndrome, tidal volume is likely an imprecise parameter for titrating lung-protective ventilation.

Prediction model for patients with acute respiratory distress syndrome: use of a genetic algorithm to develop a neural network model

BACKGROUND

Acute respiratory distress syndrome (ARDS) is associated with significantly increased risk of death, and early risk stratification may help to choose the appropriate treatment. The study aimed to develop a neural network model by using a genetic algorithm (GA) for the prediction of mortality in patients with ARDS.

METHODS

This was a secondary analysis of two multicenter randomized controlled trials conducted in forty-four hospitals that are members of the National Heart, Lung, and Blood Institute, founded to create an acute respiratory distress syndrome Clinical Trials Network. Model training and validation were performed using the SAILS and OMEGA studies, respectively. A GA was employed to screen variables in order to predict 90-day mortality, and a neural network model was trained for the prediction. This machine learning model was compared to the logistic regression model and APACHE III score in the validation cohort.

RESULTS

A total number of 1,071 ARDS patients were included for analysis. The GA search identified seven important variables, which were age, AIDS, leukemia, metastatic tumor, hepatic failure, lowest albumin, and FiO₂. A representative neural network model was constructed using the forward selection procedure. The area under the curve (AUC) of the neural network model evaluated with the validation cohort was 0.821 (95% CI [0.753-0.888]), which was greater than the APACHE III score (0.665; 95% CI [0.590-0.739]; p = 0.002 by Delong's test) and logistic regression model, albeit not statistically significant (0.743; 95% CI [0.669-0.817], p = 0.130 by Delong's test).

CONCLUSIONS

The study developed a neural network model using a GA, which outperformed conventional scoring systems for the prediction of mortality in ARDS patients.

TLR3 Regulated Poly I:C-Induced Neutrophil Extracellular Traps and Acute Lung Injury Partly Through p38 MAP Kinase

Acute lung injury (ALI) is the leading cause of morbidity and mortality in critically ill patients. Neutrophil extracellular traps (NETs) have been well documented in the ALI model of bacterial infection. In the present study, we demonstrated that poly I:C could induce pulmonary NETs. Upon poly I:C intratracheal inoculation, neutrophil infiltration in the bronchoalveolar lavage fluid (BALF) was significantly increased. Furthermore, the inflammatory cytokines IL-1β, IL-6, and TNF-α in the lung were also significantly elevated. Neutrophil depletion abolished NETs and decreased both neutrophil infiltration and IL-1β in the lung. As expected, DNase I, an inhibitor of MPO and NADPH, decreased pulmonary inflammation and NETs. Blocking of the poly I:C receptor TLR3 reduced lung inflammation and NETs. The MAPK kinase inhibitor p38 diminished the formation of NETs and restored the expression of the tight junction protein claudin-5 in the mouse lung when challenged with poly I:C. In summary, poly I:C induced the formation of pulmonary NETs and ALI, which may be associated with the activation of p38 MAPK and the decreased expression of claudin-5.

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.

Cross-sectional analysis on publication status and age representation of clinical studies addressing mechanical ventilation and ventilator-induced lung injury in infants and children

OBJECTIVES

We determined the number and time-to-public availability of study results of published and unpublished clinical studies in paediatric mechanical ventilation (MV) and ventilator-induced lung injury (VILI), which were registered as completed on ClinicalTrials.gov. Furthermore, we explored the pattern of represented research study subtopics and the corresponding study populations.

SETTING

Literature search based on ClinicalTrials.gov, PubMed and Google Scholar from 9 July 2017 to 27 September 2017.

PRIMARY AND SECONDARY OUTCOME MEASURES

Assessment, if studies included in our analysis had been published. Assessment of primary research focus, patient enrolment and age representation of the analysed studies.

RESULTS

We identified n=109 registered and completed clinical studies on paediatric MV and VILI (enrolment: 22 233 participants). 71% were published, including data from 18 647 subjects. 29% of studies were unpublished, containing data from 3586 subjects. Median time-to-public availability of study results was 22 (IQR, 12.8-41.5) months. The most important study subtopics were biophysical and technical aspects of MV (32 studies), administration of drugs to mitigate VILI through various mechanisms (40 studies) and diagnostic procedures (16 studies). n=66/109 (61%) studies exclusively focused on children below 1 year of age and n=2/109 (2%) exclusively on children between 1 and 14 years.

CONCLUSIONS

One-third of clinical studies in paediatric MV and VILI registered as completed on ClinicalTrials.gov remained unpublished and contained data on 3586 study participants. The overall median time-to-public availability of study results was longer than the deadline of 12 months mandated by the Food and Drug Administration Amendment Act of 2007. Important and clinically relevant research study subtopics were represented in the research questions investigated in paediatric MV and VILI. The study population was skewed towards children younger than 1 year which indicates, that there is a substantial need for clinical VILI research in older children.

New Morbidity and Discharge Disposition of Pediatric Acute Respiratory Distress Syndrome Survivors

OBJECTIVES

Much of the research related to pediatric acute respiratory distress syndrome has focused on inhospital mortality and interventions affecting this outcome. Limited data exist on survivors' morbidity, hospital disposition, and 1-year survival. The aim of this study was to determine new morbidity rate, discharge disposition, and 1-year mortality for survivors of pediatric acute respiratory distress syndrome.

DESIGN

Secondary analysis of prospective cohort study.

SETTING

Quaternary children's hospital.

PATIENTS

Three-hundred sixteen mechanically ventilated children with pediatric acute respiratory distress syndrome (Berlin and Pediatric Acute Lung Injury Consensus Conference criteria) between July 2011 and December 2014.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We performed secondary analysis of a prospectively recruited cohort of 316 mechanically ventilated children with pediatric acute respiratory distress syndrome between July 2011, and December 2014. Preillness and hospital discharge Functional Status Scale score were determined via chart review, and factors associated with new morbidity, defined as an increase of Functional Status Scale score of 3 or more, were analyzed. Demographic variables, pediatric acute respiratory distress syndrome characteristics, and ventilator management were tested for association with development of new morbidity, discharge disposition, and 1-year mortality. Inhospital mortality of pediatric acute respiratory distress syndrome was 13.3% (42/316). Of 274 survivors to hospital discharge, new morbidity was seen in 63 patients (23%). Discharge to rehabilitation rate was 24.5% (67/274) and associated with development of new morbidity. One- and 3-year mortality of survivors was 5.5% (15 deaths) and 8% (22 deaths) and was associated with baseline Functional Status Scale, immunocompromised status, Pediatric Risk of Mortality III, and organ failures at pediatric acute respiratory distress syndrome onset, but not with pediatric acute respiratory distress syndrome severity.

CONCLUSIONS

New morbidity was common after pediatric acute respiratory distress syndrome and appears to be intermediate phenotype between survival without morbidity and death, making it a useful metric in future interventional and outcome studies in pediatric acute respiratory distress syndrome.

Adverse Outcomes due to Aggressive Fluid Resuscitation in Children: A Prospective Observational Study

Fluid management has a major impact on the duration, severity, and outcome of critically ill children. The aim of this study was to examine the relationship between cumulative fluid overload (CFO) with mortality and morbidity in critically ill children. This was a prospective observational study wherein children (1 month-16 years) who were critically ill (with shock requiring inotropes and/or mechanically ventilated) were enrolled. CFO was defined as the sum of daily fluid balances. Daily fluid balance was calculated as a difference between fluid intake (oral and intravenous) and output (urine output, discharge from nasogastric tube) in 24 hours. Percentage of fluid overload (FO) (PFO) was calculated as the ratio of CFO with weight at admission in kilogram. The CFO and PFO at 24, 48, 72 hours and at 7 days or end of PICU stay were calculated. A total of 291 children (244 survivors and 47 non-survivors; 47% males) were included in the final analysis. A higher mortality was observed in children with higher PFO (>20% FO: 45.8% mortality vs. 14.5% < 10% FO, p  < 0.01) and CFO (10.97 ± 6.4 mL/kg in survivors vs. 13.95 ± 9.6 mL/kg in non-survivors; p  = 0.022) at 72 hours. A 1% increase in fluid overload was associated with 6% and 4% increase in mortality at 72 hours and 7 days, respectively. Similarly, the impact of every 1% increase in fluid overload on both ventilation (yes/no) and acute kidney injury (AKI; yes/no) were found to be significant for both parameters at 72 hours, but only AKI had significant correlation on seventh day. In the multivariate stepwise Cox's proportional hazard model for PICU stay and hospital stay, 3% ( p  < 0.05) and 2% ( p  > 0.05) increase were found for every 1% increase in fluid overload, respectively. Oxygenation index is also associated with fluid overload with the adjusted model estimated 0.27 units (95% confidence interval: 0.18-0.36) increase per 1% increase in fluid overload. FO was associated with increased mortality and morbidity in critically ill children.

Subtypes of pediatric acute respiratory distress syndrome have different predictors of mortality

PURPOSE

Acute respiratory distress syndrome (ARDS) is heterogeneous in etiology, which may affect outcomes. Stratification into biologically-defined subtypes may reduce heterogeneity. However, it is unknown whether pediatric ARDS has clinically relevant subtypes. We aimed to determine whether clinical characteristics and predictors of mortality differed between direct and indirect ARDS, and separately between infectious and non-infectious ARDS.

METHODS

This was a single center, prospective cohort study of 544 children with ARDS (Berlin) between July 2011 and June 2017, stratified into direct versus indirect ARDS, and separately into infectious versus non-infectious ARDS. Multiple logistic regression was used to test for predictors of mortality in the entire cohort, and separately within subtypes. Effect modification by subtype was assessed using interaction tests.

RESULTS

Direct ARDS had lower severity of illness (p < 0.001) but worse oxygenation (p < 0.001), relative to indirect. Predictors of mortality were similar for direct and indirect ARDS. When comparing infectious and non-infectious ARDS, infectious ARDS had lower severity of illness (p < 0.001), worse oxygenation (p = 0.014), and lower mortality (p = 0.013). In multivariable analysis, immunocompromised status demonstrated effect modification between infectious and non-infectious ARDS (p = 0.005 for interaction), with no association with mortality in non-infectious ARDS.

CONCLUSIONS

In children, direct and indirect ARDS have distinct clinical characteristics, but similar outcomes and similar predictors of mortality. In contrast, infectious and non-infectious ARDS demonstrate heterogeneity of clinical characteristics, mortality, and predictors of mortality, with traditional predictors of ARDS mortality only applicable to infectious ARDS.

Acute Respiratory Failure in Children

This article reviews the definition, pathophysiology, etiology, assessment, and management of acute respiratory failure in children. Acute respiratory failure is the inability of the respiratory system to maintain oxygenation or eliminate carbon dioxide. Acute respiratory failure is a common cause for admission to a pediatric intensive care unit. Most causes of acute respiratory failure can be grouped into one of three categories: lung parenchymal disease, airway obstruction, or neuromuscular dysfunction. Many patients with acute respiratory failure are managed successfully with noninvasive respiratory support; however, in severe cases, patients may require intubation and mechanical ventilation. [Pediatr Ann. 2018;47(7):e268-e273.].

Surfactants in Acute Respiratory Distress Syndrome in Infants and Children: Past, Present and Future

There is a lack of definitive data on the effective management of acute respiratory distress syndrome (ARDS) in infants and children. The development and validation of the Berlin definition (BD) for ARDS and the Pediatric Acute Lung Injury Consensus Conference (PALICC) recommendations in children represented a major advance in optimizing research and treatment, mainly due to the introduction of a severe ARDS category. Proposed reasons for the lack of consistent results with surfactants in children and infants compared with neonates include different causes, type of lung damage (direct or indirect), timing and mode of administration as well as the type of surfactant used. Secretory phospholipase A2 plays an important role in inflammation and possible dysfunction of surfactants in ARDS. Bronchoalveolar lavage (BAL) with normal saline and surfactant allows the removal of inhaled material, the recruitment of non-ventilating areas and the maintenance of the surfactant pool size. BAL with diluted surfactant allows rapid absorption of the surfactant at the air/liquid interface, which blocks the progression of pathological lung disease and in turn disrupts the inflammatory cycle. Importantly, it is now recognized that the type of surfactant, the time of administration and the method of administration could all play an important role in the management of ARDS, and there is evidence that surfactant is effective and well tolerated in children and infants with ARDS.