Mortality in Pediatric Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

Pediatric Acute Respiratory Distress Syndrome Severity and Health-Related Quality of Life Outcomes: Single-Center Retrospective Cohort, 2011-2017

OBJECTIVES

To determine factors associated with health-related quality of life (HRQL) decline among pediatric acute respiratory distress syndrome (PARDS) survivors.

DESIGN

Retrospective cohort study.

SETTING

Academic children's hospital.

PATIENTS

Three hundred fifteen children 1 month to 18 years old with an unplanned PICU admission from December 2011 to February 2017 enrolled in the hospital's Outcomes Assessment Program.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Pre-admission baseline and median 6-week post-discharge HRQL were assessed using the Pediatric Quality of Life Inventory or the Functional Status II-R. Patients meeting retrospectively applied Second Pediatric Acute Lung Injury Consensus Conference criteria for PARDS were identified, and PARDS severity was classified using binary (mild/moderate, severe) and trichotomous (mild, moderate, severe) categorization for noninvasive ventilation and invasive mechanical ventilation (IMV). PARDS occurred in 41 of 315 children (13.0%). Clinically important HRQL decline (≥ 4.5 points) occurred in 17 of 41 patients (41.5%) with PARDS and 64 of 274 without PARDS (23.4%). On multivariable generalized linear regression adjusted for age, baseline Pediatric Overall Performance Category, maximum nonrespiratory Pediatric Logistic Organ Dysfunction score, diagnosis, length of stay, and time to follow-up, PARDS was associated with HRQL decline (adjusted relative risk [aRR], 1.70; 95% CI, 1.03-2.77). Four-hour and maximum PARDS severity were the only factors associated with HRQL decline. HRQL decline occurred in five of 18 patients with mild PARDS at 4 hours, five of 13 with moderate PARDS (aRR 2.35 vs. no PARDS [95% CI, 1.01-5.50]), and seven of ten with severe PARDS (aRR 2.56 vs. no PARDS [95% CI, 1.45-4.53]). The area under the receiver operating characteristic curve for discrimination of HRQL decline for IMV patients was 0.79 (95% CI, 0.66-0.91) for binary and 0.80 (95% CI, 0.69-0.93) for trichotomous severity categorization.

CONCLUSIONS

HRQL decline is common among children surviving PARDS, and risk of decline is associated with PARDS severity. HRQL decline from baseline may be an efficient and clinically meaningful endpoint to incorporate into PARDS clinical trials.

Differential changes in expression of inflammatory mRNA and protein after oleic acid-induced acute lung injury

Background: Acute Respiratory Distress syndrome (ARDS) is a clinical syndrome of noncardiac pulmonary edema and inflammation leading to acute respiratory failure. We used the oleic acid infusion pig model of ARDS resembling human disease to explore cytokine changes in white blood cells (WBC) and plasma proteins, comparing baseline to ARDS values. Methods: Nineteen juvenile female swine were included in the study. ARDS defined by a PaO2/FiO2 ratio < 300 was induced by continuous oleic acid infusion. Arterial blood was drawn before and during oleic acid infusion, and when ARDS was established. Cytokine expression in WBC was analyzed by RT-qPCR and plasma protein expression by ELISA. Results: The median concentration of IFN-γ mRNA was estimated to be 59% (p = 0.006) and of IL-6 to be 44.4% (p = 0.003) of the baseline amount. No significant changes were detected for TNF-α, IL-17, and IL-10 mRNA expression. In contrast, the concentrations of plasma IFN-γ and IL-6 were significantly higher (p = 0.004 and p = 0.048 resp.), and TNF-α was significantly lower (p = 0.006) at ARDS compared to baseline. Conclusions: The change of proinflammatory cytokines IFN-γ and IL-6 expression is different comparing mRNA and plasma proteins at oleic acid-induced ARDS compared to baseline. The migration of cells to the lung may be the cause for this discrepancy.

Investigation of Factors Influencing Infant Mortality at Greater Accra Regional Hospital, Ghana

Background

Annually, 5.4 million children under five face mortality, with 2.5 million deaths in the first month, 1.6 million between one and eleven months, and 1.3 million aged one to four. Despite global strides, sub-Saharan Africa, including Ghana, grapples with persistent high child mortality. This study employs statistical methods to pinpoint factors driving under-five mortality in the Greater Accra Regional Hospital.

Methods

The data was acquired from Greater Accra Regional Hospital, Ghana, spanning January to December 2020. The data comprised all under-five deaths recorded in the hospital in 2020. The statistical tools employed were the chi-square test of association and the multinomial logistic regression model.

Results

In 2020, there were 238 cases of under-five mortality recorded in the hospital, with males constituting the majority (55%). About 85% of these cases occurred within the first month of birth, primarily attributed to respiratory distress, prematurity, and sepsis. Notably, meconium aspiration was the least common among grouped diagnoses. The test of association and multinomial logistic model emphasised the child's age, birth type, and weight at birth as significant factors influencing child mortality. Conversely, attributes like sex, marital status, and mother's age displayed no notable association with the diagnosis of death.

Conclusion

The study on child mortality at the Greater Accra Regional Hospital unveils key factors shaping child health outcomes, emphasising the role of age, birth type, and weight. While specific demographics show no significant association, identified predictors are vital for targeted interventions. Proposed strategies encompass education programs, improved care, birthing practices, and data-driven policies.

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.

Analysis of risk factors for acute attacks complicated by respiratory failure in children with asthma

Objective

To describe the proportion and clinical characteristics of hospitalized children with acute asthma attacks complicated by respiratory failure and to analyze the risk factors.

Methods

This retrospective study analyzed hospital admissions of children and adolescents with acute asthma attacks between January 2016 and December 2021. Inclusion criteria were used to identify eligible cases, and demographic information and disease characteristics were collected. Patients were categorized into respiratory failure group and the other group based on the result of artery blood gas analysis. Multivariate logistic regression was utilized to investigate the risk factors associated with respiratory failure resulting from acute asthma attacks. The data were analyzed using SPSS 22.0, and significance was considered at P < 0.05.

Results

Our research involved 225 participants, with 18.7% diagnosed with respiratory failure. The respiratory failure group was found to be younger and have higher percentage of male, while birth weight, nationality, and type of residence did not differ between the two groups. In the respiratory failure group, a significant difference was observed in emergency hospitalization, ICU treatment, severe to critical attack, dyspnea and allergy history. The two groups did not differ in admission season, first asthma diagnosis, respiratory infection and comorbidity. The respiratory failure group exhibited a higher proportion of atopy-only asthma and a lower proportion of T2-high asthma. The eosinophil count, and eosinophil percentage were lower in the respiratory failure group, while neutrophil count was higher. Having a history of allergies (OR = 2.46, 95% CI: 1.08-5.59) and neutrophil count (OR = 1.10, 95% CI: 1.00-1.21) were the risk factors for respiratory failure in children with asthma. There also existed that the risk of respiratory failure increases with decreasing age of the children (OR = 0.85, 95% CI: 0.73-0.99).

Conclusion

Notably, risk factors for respiratory failure in hospitalized asthma children include age, having a history of allergies, and neutrophil count. The identification of the above factors and the implementation of timely intervention can optimize the treatment of asthma in children.

Pediatric Acute Respiratory Distress Syndrome in South African PICUs: A Multisite Point-Prevalence Study

OBJECTIVES

To describe the prevalence of pediatric acute respiratory distress syndrome (pARDS) and the characteristics of children with pARDS in South African PICUs.

DESIGN

Observational multicenter, cross-sectional point-prevalence study.

SETTING

Eight PICUs in four South African provinces.

PATIENTS

All children beyond the neonatal period and under 18 years of age admitted to participating PICUs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Clinical and demographic data were prospectively collected on a single day of each month, from February to July 2022, using a centralized database. Cases with or at risk of pARDS were identified using the 2015 Pediatric Acute Lung Injury Consensus Conference criteria. Prevalence was calculated as the number of children meeting pARDS criteria/the total number of children admitted to PICU at the same time points. Three hundred ten patients were present in the PICU on study days: 166 (53.5%) male, median (interquartile range [IQR]) age 9.8 (3.1-32.9) months, and 195 (62.9%) invasively mechanically ventilated. Seventy-one (22.9%) patients were classified as being "at risk" of pARDS and 95 patients (prevalence 30.6%; 95% CI, 24.7-37.5%) fulfilled pARDS case criteria, with severity classified as mild (58.2%), moderate (25.3%), and severe (17.6%). Median (IQR) admission Pediatric Index of Mortality 3 risk of mortality in patients with and without pARDS was 5.6 (3.4-12.1) % versus 3.9 (1.0-8.2) % ( p = 0.002). Diagnostic categories differed between pARDS and non-pARDS groups ( p = 0.002), with no difference in age, sex, or presence of comorbidities. On multivariable logistic regression, increasing admission risk of mortality (adjusted odds ratio [aOR] 1.02; 95% CI, 1.00-1.04; p = 0.04) and being admitted with a respiratory condition (aOR 2.64; 95% CI, 1.27-5.48; p = 0.01) were independently associated with an increased likelihood of having pARDS.

CONCLUSIONS

The 30.6% prevalence of pARDS in South Africa is substantially higher than reports from other sociogeographical regions, highlighting the need for further research in this setting.

The Modified Clinical Progression Scale for Pediatric Patients: Evaluation as a Severity Metric and Outcome Measure in Severe Acute Viral Respiratory Illness

OBJECTIVES

To develop, evaluate, and explore the use of a pediatric ordinal score as a potential clinical trial outcome metric in children hospitalized with acute hypoxic respiratory failure caused by viral respiratory infections.

DESIGN

We modified the World Health Organization Clinical Progression Scale for pediatric patients (CPS-Ped) and assigned CPS-Ped at admission, days 2-4, 7, and 14. We identified predictors of clinical improvement (day 14 CPS-Ped ≤ 2 or a three-point decrease) using competing risks regression and compared clinical improvement to hospital length of stay (LOS) and ventilator-free days. We estimated sample sizes (80% power) to detect a 15% clinical improvement.

SETTING

North American pediatric hospitals.

PATIENTS

Three cohorts of pediatric patients with acute hypoxic respiratory failure receiving intensive care: two influenza (pediatric intensive care influenza [PICFLU], n = 263, 31 sites; PICFLU vaccine effectiveness [PICFLU-VE], n = 143, 17 sites) and one COVID-19 ( n = 237, 47 sites).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Invasive mechanical ventilation rates were 71.4%, 32.9%, and 37.1% for PICFLU, PICFLU-VE, and COVID-19 with less than 5% mortality for all three cohorts. Maximum CPS-Ped (0 = home at respiratory baseline to 8 = death) was positively associated with hospital LOS ( p < 0.001, all cohorts). Across the three cohorts, many patients' CPS-Ped worsened after admission (39%, 18%, and 49%), with some patients progressing to invasive mechanical ventilation or death (19%, 11%, and 17%). Despite this, greater than 76% of patients across cohorts clinically improved by day 14. Estimated sample sizes per group using CPS-Ped to detect a percentage increase in clinical improvement were feasible (influenza 15%, n = 142; 10%, n = 225; COVID-19, 15% n = 208) compared with mortality ( n > 21,000, all), and ventilator-free days (influenza 15%, n = 167).

CONCLUSIONS

The CPS-Ped can be used to describe the time course of illness and threshold for clinical improvement in hospitalized children and adolescents with acute respiratory failure from viral infections. This outcome measure could feasibly be used in clinical trials to evaluate in-hospital recovery.

Nutritional Support in Children Meeting the At-Risk for Pediatric Acute Respiratory Distress Syndrome Criteria

Pediatric acute respiratory distress syndrome (PARDS) is a prevalent condition in the PICU with a high morbidity and mortality, but effective preventative strategies are lacking.

OBJECTIVES

To examine associations between early enteral nutrition (EN) and PICU outcomes in a cohort of children meeting the 2015 Pediatric Acute Lung Injury Consensus Conference "at-risk" for pediatric acute respiratory distress syndrome (ARF-PARDS) criteria.

DESIGN SETTING AND PARTICIPANTS

This was a single-center, electronic health record-based retrospective chart review. We included children less than or equal to 18 years-old admitted to our mixed medical-surgical PICU from January 2017 to December 2018 who met ARF-PARDS criteria within 48 hours of admission. Children were categorized as receiving "early" EN if feeds were initiated within 48 hours of admission. All others were categorized as "delayed" EN.

MAIN OUTCOMES AND MEASURES

Extracted data included demographics, illness characteristics including primary diagnosis and Pediatric Risk of Mortality (PRISM) III score, respiratory support and oxygenation indices, nutritional data, and PICU length of stay (LOS). The primary outcome of interest was subsequent diagnosis of PARDS.

RESULTS

Of 201 included children, 152 (75.6%) received early EN. The most common admission diagnoses were pneumonia, bronchiolitis, and influenza. Overall, 21.4% (n = 43) of children developed PARDS. Children receiving early EN had a subsequent diagnosis of PARDS less often then children receiving delayed EN (15.1% vs 40.8%; p < 0.001), an association that persisted after adjusting for patient demographics and illness characteristics, including PRISM III and diagnosis (adjusted odds ratio, 0.24; 95% CI, 0.10-0.58; p = 0.002). Early EN was also associated with a shorter PICU LOS in univariate analysis (2.2 d [interquartile range, 1.5-3.4 d] vs 4.2 d [2.7-8.9 d]; p < 0.001).

CONCLUSIONS AND RELEVANCE

In this single-center, retrospective cohort study, compared with children with ARF-PARDS who received late EN, those who received early EN demonstrated a reduced odds of subsequent diagnosis of PARDS, and an unadjusted reduction in PICU LOS when compared with delayed EN. Prospective studies should be designed to confirm these findings.

Comparison of the Montreux definition with the Berlin definition for neonatal acute respiratory distress syndrome

To compare the similarities and differences between the Montreux definition and the Berlin definition in terms of the prevalence, mortality, and complications of neonatal acute respiratory distress syndrome (ARDS). We retrospectively analyzed the data of neonates with respiratory failure treated in a neonatal intensive care unit (NICU) between 1 November 2019 and 31 December 2021. In total, 554 infants had neonatal ARDS (524 infants, Montreux definition; 549 infants, Berlin definition). The prevalence (3.1% vs. 3.3%, p = 0.438) and mortality (18.9% vs.18.0%, p = 0.716) of neonatal ARDS did not differ between the definitions. Among the 519 infants meeting both definitions, key clinical outcomes did not differ between the definitions such as ventilation duration, NICU stay, complication rates, and antibiotic use, except for nitric oxide inhalation. The Montreux and Berlin definitions identified an additional 5 and 30 patients, respectively, not captured by the other definition. The rate of inhaled nitric oxide treatment (20.0% vs. 0%, p = 0.013), air leaks (20.0% vs. 0%, p = 0.013), and invasive ventilation duration (110.00 vs.0.00 h, p = 0.002) significantly differed between the above two groups. Sixty-two patients had moderate and severe ARDS according to the Montreux and Berlin definitions, respectively. The rates of adverse outcomes (e.g., mortality, invasive ventilation time) among these patients were similar to the rates among patients with moderate ARDS according to both definitions than among patients with severe ARDS according to both definitions.  Conclusion: The prevalence, mortality, and most complications of neonatal ARDS were similar between the Montreux and Berlin definitions, which mainly differed in terms of the severity of neonatal ARDS. What is Known: • The Montreux definition was first proposed for the diagnosis of neonatal acute respiratory distress syndrome and was established in 2017. To date, the Montreux definition has not been compared with other diagnostic definitions of ARDS. What is New: • The study suggests that perinatal lung disease need not be excluded in the diagnosis of neonatal ARDS, and that the Montreux definition is more applicable to neonates, taking into account their specific physiological characteristics.

Alveolar dead space fraction is not associated with early RV systolic dysfunction in pediatric ARDS

PRIMARY HYPOTHESIS

We hypothesized that higher alveolar dead space fraction (AVDSf) at pediatric acute respiratory distress syndrome (PARDS) onset would be associated with right ventricular (RV) systolic dysfunction within the first 24 h of PARDS.

STUDY DESIGN AND METHODS

We performed a retrospective single-center cohort study of PARDS patients with clinically obtained echocardiograms within 24 h. Primary exposure was AVDSf at PARDS onset. Primary outcome was RV systolic dysfunction as defined by RV global longitudinal strain (GLS) (>-18%). Secondary outcomes included pulmonary hypertension (PH) and RV systolic dysfunction as defined by other echocardiogram parameters, and measures of oxygenation. Unadjusted and adjusted logistic and linear regression were used to investigate AVDSf associations with outcomes.

RESULTS

Ninety-one patients were included: median age 6.2 years, 46% female, and 65% with moderate or severe PARDS. Median AVDSf was 0.2 (interquartile range [IQR] 0.0-0.3), 33% had RV dysfunction, and 21% had PH. Unadjusted and adjusted logistic regression showed no association between AVDSf and RV systolic dysfunction or PH by any echocardiographic measure, but unadjusted and adjusted linear regression did show an association between AVDSf and PaO2 /FiO2 .

CONCLUSION

AVDSf at PARDS onset was not associated with RV systolic dysfunction or PH within 24 h but was associated with PaO2 /FiO2 ratio and may be more reflective of pulmonary causes of ventilation-perfusion mismatch. Future investigations should focus on clarifying the clinical utility of AVDSf in relation to existing metrics throughout the course of PARDS.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The role of G protein-coupled receptor in neutrophil dysfunction during sepsis-induced acute respiratory distress syndrome

Sepsis is defined as a life-threatening dysfunction due to a dysregulated host response to infection. It is a common and complex syndrome and is the leading cause of death in intensive care units. The lungs are most vulnerable to the challenge of sepsis, and the incidence of respiratory dysfunction has been reported to be up to 70%, in which neutrophils play a major role. Neutrophils are the first line of defense against infection, and they are regarded as the most responsive cells in sepsis. Normally, neutrophils recognize chemokines including the bacterial product N-formyl-methionyl-leucyl-phenylalanine (fMLP), complement 5a (C5a), and lipid molecules Leukotriene B4 (LTB4) and C-X-C motif chemokine ligand 8 (CXCL8), and enter the site of infection through mobilization, rolling, adhesion, migration, and chemotaxis. However, numerous studies have confirmed that despite the high levels of chemokines in septic patients and mice at the site of infection, the neutrophils cannot migrate to the proper target location, but instead they accumulate in the lungs, releasing histones, DNA, and proteases that mediate tissue damage and induce acute respiratory distress syndrome (ARDS). This is closely related to impaired neutrophil migration in sepsis, but the mechanism involved is still unclear. Many studies have shown that chemokine receptor dysregulation is an important cause of impaired neutrophil migration, and the vast majority of these chemokine receptors belong to the G protein-coupled receptors (GPCRs). In this review, we summarize the signaling pathways by which neutrophil GPCR regulates chemotaxis and the mechanisms by which abnormal GPCR function in sepsis leads to impaired neutrophil chemotaxis, which can further cause ARDS. Several potential targets for intervention are proposed to improve neutrophil chemotaxis, and we hope that this review may provide insights for clinical practitioners.

Pediatric Critical Care Nursing Research Priorities in Asia: An eDelphi Study

OBJECTIVES

To identify nursing research priorities in pediatric critical care in Asia.

DESIGN

We conducted a modified three-round eDelphi survey with pediatric critical care nurses in Asia. The eDelphi technique has been extensively used within health research to achieve a common viewpoint from experts using questionnaires to gather research priorities. In round 1, participants were asked to list three to five research topics that they deemed important. These topics were thematically analyzed and categorized into a questionnaire. Participants rated the research topics in round 2 on a 6-point scale (1 = not important to 6 = extremely important). In round 3, the same questionnaire was used with addition of the calculated mean scores from round 2 for each topic. Research topics ranked among the top 10 were considered extremely important.

SETTINGS

Twenty-two PICUs in eight Asian countries.

SUBJECTS

Clinical nurses, managers, educators, and researchers.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

In round 1, 146 PICU nurses across eight countries provided 520 research topics. Topics from round 1 were categorized into seven domains with 52 research topics. Prioritized research topics included early recognition of patient deterioration (mean 5.58 ± 0.61), prevention of healthcare-associated infections (mean 5.47 ± 0.70), and interventions to reduce compassion fatigue (mean 5.45 ± 0.80). The top three research domains were end-of-life care (mean 5.34 ± 0.68), professionalism (mean 5.34 ± 0.69), and management of pain, sedation, and delirium (5.32 ± 0.72).

CONCLUSIONS

This first PICU nursing research prioritization exercise within Asia identified key nursing research themes that should be prioritized and provide a framework for future collaborative studies.

Effect of preoperative pulse oximeter oxygen saturation on postoperative prolonged mechanical ventilation in patients with tetralogy of Fallot

Background

As an easily accessible and intervened clinical indicator, preoperative pulse oximeter oxygen saturation (SpO₂) is an important factor affecting the prognosis of patients with tetralogy of Fallot (TOF). However, whether SpO₂ is associated with postoperative mechanical ventilation (MV) time remains unknown. Therefore, this study aimed to investigate the impact of preoperative SpO₂ on postoperative prolonged mechanical ventilation (PMV) in children with TOF.

Materials and methods

The study included children younger than 18 years who underwent corrective operations for TOF between January 2016 and December 2018 in Fuwai Hospital, China. Univariate and multivariate logistic regression analyses were used to evaluate the influence of preoperative SpO₂ on postoperative PMV. After identifying SpO₂ as an independent risk factor for PMV, patients were further divided into two groups according to the cutoff value of SpO₂, and propensity score matching (PSM) analysis was used to eliminate the effect of confounding factors. The logistic regression was used to compare the outcomes between the two groups after PSM.

Results

A total of 617 patients were finally enrolled in this study. By the univariable and multivariate logistic analysis, four independent risk factors for PMV were determined, namely, SpO₂, surgical technique, aortic cross-clamp time, and intraoperative minimum temperature. According to the outcomes of 219 paired patients after PSM, the incidence of PMV was significantly higher in patients with lower preoperative SpO₂ (P = 0.022). Also, there was significant increase in mechanical ventilation time (P = 0.019), length of intensive care unit stay (P = 0.044), postoperative hospital stay (P = 0.006), hospital stay (P = 0.039), and hospitalization cost (P = 0.019) at the lower preoperative SpO₂ level.

Conclusion

Low preoperative SpO₂ represents an independent risk factor of postoperative PMV in children with TOF.

P50 implies adverse clinical outcomes in pediatric acute respiratory distress syndrome by reflecting extrapulmonary organ dysfunction

Hypoxemia and multiple organ dysfunction are significant contributors to mortality in patients with pediatric acute respiratory distress syndrome (PARDS). P50, the oxygen tension at which hemoglobin is 50% saturated, is a measure of hemoglobin-oxygen affinity, and its alteration might have implications for tissue hypoxia and organ dysfunction. The purpose of this single-center, retrospective study was to evaluate P50 levels in PARDS and to determine the association between P50 and clinical outcomes. The study included 212 children diagnosed with PARDS according to the Pediatric Acute Lung Injury Consensus Conference definition who required invasive mechanical ventilation and had arterial blood gas results of hemoglobin oxygen saturation < 97% at the time of diagnosis. P50 levels were calculated using Doyle’s method, and organ dysfunction was assessed using the Pediatric Logistic Organ Dysfunction-2 score. Most patients exhibited more than one dysfunctional extrapulmonary organ at PARDS onset. P50 increased with increasing PARDS severity (mild (26.6 [24.9–29.6]), moderate (26.8 [25.0–29.5]), and severe PARDS (29.1 [26.1–32.4] mmHg; P = 0.025). Moreover, P50 demonstrated a significant positive association with extrapulmonary organ dysfunction score (β = 0.158, P = 0.007) and risk of mortality (adjusted hazard ratio, 1.056; 95% confidence interval, 1.015–1.098; P = 0.007), irrespective of initial PARDS severity. The relationship between P50 and mortality was largely mediated by extrapulmonary organ dysfunction. A high P50 value at the time of PARDS diagnosis may be associated with mortality via dysfunctional extrapulmonary organs. Future studies should consider P50 as a potential candidate index for risk stratification of PARDS patients.

Pediatric Acute Respiratory Distress Syndrome in India: Time for Collaborative Study?

How to cite this article: Solomon R. Pediatric Acute Respiratory Distress Syndrome in India: Time for Collaborative Study? Indian J Crit Care Med 2022;26(8):896–897.

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.

Outcomes of Pediatric Drowning in the Pediatric Intensive Care Unit

Drowning remains a leading cause of death in children. Knowledge of outcomes of these patients who survive drowning but require critical care is lacking. We aim to study the current mortality rate, describe interventions and associated diagnoses, and examine factors related to risk of death in drowning victims admitted to the pediatric intensive care unit (PICU). We conducted a retrospective multicenter cohort study utilizing data from the Virtual Pediatric Systems Database in 143 PICUs between January 1, 2010, and December 31, 2019. Patients between 0 and 18 years of age admitted to a PICU with a diagnosis of drowning were included. The primary outcome was death prior to hospital discharge. Predictors included demographics, critical care interventions, and associated diagnoses. Odds ratios were calculated using multivariate logistic regression. There were 4,855 patients admitted with drowning across the study period. The overall PICU mortality rate in this cohort was 18.7%. Factors associated with an increased odds of death included being transported from an outside hospital, mechanical ventilation, central line placement, cardiac arrest, respiratory failure, and hypoxic ischemic encephalopathy. In 2,479 patients requiring mechanical ventilation, 63 were treated with extracorporeal membrane oxygenation which was not associated with mortality. This data provide updated insight into pediatric drowning victims requiring critical care and their prognosis, as it relates to the interventions they receive. Overall PICU mortality rates for drowning are higher than overall PICU mortality and mortality from other causes of injury. These findings have implications for the care of drowned children in ICU environments and in continued preventive efforts.

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

OBJECTIVES

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

DESIGN

Prospective, international, observational, cohort study.

SETTING

Fifteen academic neonatal ICUs.

PATIENTS

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

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSIONS

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

Necrotizing pneumonia requiring prolonged extracorporeal membrane oxygenation: Pushing the boundaries in pediatric ECMO

Extracorporeal membrane oxygenation (ECMO) is a life‐saving rescue therapy used in acute respiratory failure refractory to invasive mechanical ventilation. Recent studies on positive outcomes of extended ECMO therapy are promising. We describe a case of a 2‐year 8‐month‐old female child with necrotizing pneumonia secondary to Streptococcus pneumoniae, Influenza A, and Mycoplasma pneumoniae, who survived with intact neurological function and no long‐term adverse outcomes after a prolonged ECMO run of 86 days. To the best of our knowledge, this is one of the longer durations of ECMO with transplant‐free survival in a pediatric patient requiring respiratory support with good recovery and a good functional outcome. Allowing time for native lung recovery is pivotal for optimal recovery, despite significant lung injury due to the underlying disease process. With evolving ECMO experience, clinicians may need to re‐consider the conventional maximum duration of ECMO in children with severe respiratory failure on a case‐by‐case basis.

Outcome of Extracorporeal Membrane Oxygenation for Pediatric Patients With Neoplasm: An Extracorporeal Life Support Organization Database Study (2000-2019)

OBJECTIVES

This study update in usage and outcomes of pediatric extracorporeal membrane oxygenation (ECMO) for patients with neoplasm analyzed according to demographics, clinical variables, and complications.

DESIGN

Retrospective database review of the Extracorporeal Life Support Organization registry from the last 2 decades (2000-2019). The data were divided between two decades in order to compare patients' backgrounds and outcomes over time.

SETTING

ECMO centers reporting to Extracorporeal Life Support Organization.

PATIENTS

Patients equal to or younger than 18 years old with International Classification of Diseases, 9th Revision and International Classification of Diseases, 10th Revision codes that referred to neoplasms who were managed with ECMO.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographics, cancer subtype, clinical variables, and ECMO complications were assessed in relation to the primary study outcome of survival to hospital discharge. Nine-hundred two patients met inclusion criteria; 699 patients were in the latest decade, which is more than three times the number from the previous decade (203 patients). On univariate analysis, compared with the previous decade, in the later decade, ECMO was more frequently applied in patients with pre-ECMO cardiac arrest (31.3% vs 17.1%; p < 0.001), and/or lower oxygenation index (38.0 vs 48.1; p < 0.001). We failed to identify a difference in survival between the 2 decades (42.8% vs 37.9%; p = 0.218). On multivariable analysis, diagnosis of hematologic malignancy, post-cardiopulmonary resuscitation support type, hematopoietic stem cell transplant, and age older than seven were each associated with greater odds of mortality.

CONCLUSIONS

The use of ECMO in children with neoplasm has expanded over the latest decade with changes in patient selection. Mortality remains unchanged. Hence, although the clinician still should stay cautious in its application, ECMO can be considered as an option to rescue pediatric oncologic patients in the setting of worsening cardiopulmonary status in the PICU.

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.

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.

The Association Between Oxygenation Status at 24 h After Diagnosis of Pulmonary Acute Respiratory Distress Syndrome and the 30-Day Mortality among Pediatric Oncological Patients

BACKGROUND

Pediatric oncology patients with acute respiratory distress syndrome (ARDS) secondary to pneumonia are at high risk of mortality. Our aim was to describe the epidemiology of ARDS in this clinical population and to identify the association between the oxygenation status at 24 h after diagnosis and the 30-day mortality rates, stratified by the severity of ARDS.

METHODS

This was a retrospective cohort study of 82 pediatric oncology patients, with a median age of 4 years, admitted to our pediatric intensive care unit with a diagnosis of ARDS between 2013 and 2021. Demographic and clinical factors were compared between the survivor (n = 52) and non-survivor (n = 30) groups. Univariate and multivariate Cox proportional hazards regression models were used to determine the association between the oxygenation status at 24 h after diagnosis and the 30-day mortality rates.

RESULTS

The mean airway pressure at ARDS diagnosis, PaO₂/FiO₂ (P/F) ratio, oxygenation index (OI) value, peak inspiratory pressure, and lactate level at 24 h after ARDS diagnosis, as well as complications (i.e., septicemia and more than two extrapulmonary organ failures) and adjunctive continuous renal replacement therapy, were significant mortality risk factors. After adjusting for other covariates, the oxygenation status P/F ratio (Hazard ratio [HR] = 0.98, 95% confidence interval [CI] = 0.96-1.00, P = 0.043) and OI value (HR = 1.12, 95% CI = 1.02-1.23, P = 0.016) at 24 h remained independent mortality risk factors. According to the Kaplan-Meier survival curve, a low P/F ratio (≤ 150) and high OI (>10) were associated with a higher risk of 30-day mortality (50.9 and 52.9%, respectively; both P < 0.05).

CONCLUSION

The P/F ratio and OI value measured at 24 h after ARDS diagnosis can provide a better stratification of patients according to ARDS disease severity to predict the 30-day mortality risk.

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.

Enteral feeding and the microbiome in critically ill children: a narrative review

OBJECTIVE

This narrative review summarizes our current knowledge on the interplay between enteral nutrition (EN) and gut microbiota in critically ill children, using examples from two commonly encountered diagnoses in the pediatric intensive care unit (PICU): severe sepsis and acute respiratory distress syndrome (ARDS). This review will also highlight potential areas of therapeutic interventions that should be explored in future studies.

BACKGROUND

Critically ill children display extreme dysbiosis in their gut microbiome. Factors within the PICU that are often associated with dysbiosis include the use of broad-spectrum antibiotics, proton-pump inhibitors (PPIs), intravenous morphine, and fasting. Dysbiosis can potentially lead to adverse clinical outcomes (e.g., nosocomial infection, and prolonged hospitalization). EN may modulate dysbiosis. The gut microbiota is involved in the breaking down of macronutrients, mainly carbohydrates and proteins. Fermentation of undigestible carbohydrate (e.g., inulin and oligosaccharides), and amino acids by large intestine microbiota produces short chain fatty acids (SCFAs). SCFAs serve as the main fuel source for enterocytes and help to maintain healthy gut lining. Changes to selected components of macronutrients can result in alterations in gut microbiome and have potentially beneficial effects in patients in the PICU.

METHODS

A comprehensive search of the MEDLINE, Cochrane Library and Google Scholar databases was conducted using appropriate MESH terms and keywords. In this narrative review, we provide a summary of current knowledge on effect of EN on gut microbiota in pediatric studies, but also describes animal- and lab-based, as well as adult studies where relevant.

CONCLUSIONS

The gut microbiome can be altered by dietary modifications and common PICU practices and treatment. Although there are strong associations in restoring eubiosis and improvement in clinical outcomes, proving causality remains challenging. Further microbiome research is needed to provide mechanistic insights into the impact of the ever changing gut microbiome. In the future, new microbiota targeted therapies could potentially be the treatment of challenging PICU conditions and restore homeostasis in these children.

Sex-dependent acrolein sensitivity in mice is associated with differential lung cell, protein, and transcript changes

Acrolein is a reactive inhalation hazard. Acrolein's initial interaction, which in itself can be function-altering, is followed by time-dependent cascade of complex cellular and pulmonary responses that dictate the severity of the injury. To investigate the pathophysiological progression of sex-dependent acrolein-induced acute lung injury, C57BL/6J mice were exposed for 30 min to sublethal, but toxic, and lethal acrolein. Male mice were more sensitive than female mice. Acrolein of 50 ppm was sublethal to female but lethal to male mice, and 75 ppm was lethal to female mice. Lethal and sublethal acrolein exposure decreased bronchoalveolar lavage (BAL) total cell number at 3 h after exposure. The cell number decrease was followed by progressive total cell and neutrophil number and protein increases. The BAL total cell number in female mice exposed to a sublethal, but not lethal dose, returned to control levels at 16 h. In contrast, BAL protein content and neutrophil number were higher in mice exposed to lethal compared to sublethal acrolein. RNASeq pathway analysis identified greater increased lung neutrophil, glutathione metabolism, oxidative stress responses, and CCL7 (aka MCP-3), CXCL10 (aka IP-10), and IL6 transcripts in males than females, whereas IL10 increased more in female than male mice. Thus, the IL6:IL10 ratio, an indicator of disease severity, was greater in males than females. Further, H3.3 histone B (H3F3B) and pro-platelet basic protein (PPBP aka CXCL7), transcripts increased in acrolein exposed mouse BAL and plasma at 3 h, while H3F3B protein that is associated with neutrophil extracellular traps formation increased at 12 h. These results suggest that H3F3B and PPBP transcripts increase may contribute to extracellular H3F3B and PPBP proteins increase.

High burden of acquired morbidity in survivors of pediatric acute respiratory distress syndrome

INTRODUCTION

With improving mortality rates in pediatric acute respiratory distress syndrome (PARDS), functional outcomes in survivors are increasingly important. We aim to describe the change in functional status score (FSS) from baseline to discharge and to identify risk factors associated with poor functional outcomes.

METHODS

We examined clinical records of patients with PARDS admitted to our pediatric intensive care unit (PICU) from 2009 to 2016. Our primary outcome was acquired morbidity at PICU and hospital discharge (defined by an increase in FSS ≥3 points above baseline). We included severity of illness scores and severity of PARDS in our bivariate analysis for risk factors for acquired morbidity.

RESULTS

There were 181 patients with PARDS, of which 90 (49.7%) survived. Median pediatric index of mortality 2 score was 4.05 (1.22, 8.70) and 21 (23.3%) survivors had severe PARDS. A total of 59 (65.6%) and 14 (15.6%) patients had acquired morbidity at PICU and hospital discharge, respectively. Median baseline FSS was 6.00 (6.00, 6.25), which increased to 11.00 (8.75, 12.00) at PICU discharge before decreasing to 7.50 (6.00, 9.25) at hospital discharge. All patients had significantly higher FSS at both PICU and hospital discharge median compared to baseline. Feeding and respiratory were the most affected domains. After adjusting for severity of illness, severity categories of PARDS were not a risk factor for acquired morbidity.

CONCLUSION

Acquired morbidity in respiratory and feeding domains was common in PARDS survivors. Specific attention should be given to these two domains of functional outcomes in these children.

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.

Role of Sildenafil in Management of Pediatric Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) has high mortality and multiple therapeutic strategies have been used to improve the outcome. Inhaled nitric oxide (INO), a pulmonary vasodilator, is used to improve oxygenation. This study was conducted to determine the role of sildenafil, an oral vasodilator, to improve oxygenation and mortality in pediatric ARDS (PARDS). The prevalence of pulmonary hypertension in PARDS was studied as well. Inclusion criteria included children (1–18 years) with ARDS requiring invasive ventilation admitted to the pediatric intensive care unit of a teaching hospital in Northern India over a 1-year period of time. Thirty-five patients met the inclusion criteria. Cardiologist performed a detailed echocardiogram to determine pulmonary arterial pressure (PAP). Patients with persistent hypoxemia were started on oral sildenafil. The majority (77%) patients had a primary pulmonary etiology of PARDS. Elevated PAP (>25 mm Hg) was detected in 54.3% patients at admission. Sildenafil was given to 20 patients who had severe and persistent hypoxemia. Oxygenation improved in most patients after the first dose with statistically significant improvement in PaO2/FiO2 ratios at both 12 and 24 hours following initiation of therapeutic dosing of sildenafil. Improvement in oxygenation occurred irrespective of initial PAP. Outcomes included a total of 57.1% patients discharged, 28.6% discharged against medical advice (DAMA), and a 14.3% mortality rate. Mortality was related to the severity of PARDS and not the use of sildenafil. This is the first study to determine the effect of sildenafil in PARDS. Sildenafil led to improvement in oxygenation in nearly all the cases without affecting mortality. Due to unavailability of INO in most centers of developing countries, sildenafil may be considered as an inexpensive alternative in cases of persistent hypoxemia in PARDS. We recommend additional randomized controlled trials to confirm the effect of sildenafil in PARDS as determined in this study.

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.

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

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

The Clinical Characteristics of ARDS in Children With Hematological Neoplasms

In order to explore the clinical characteristics of pediatric patients admitted to the pediatric intensive care unit (PICU) who suffered from hematological neoplasms complicated with acute respiratory distress syndrome (ARDS), we retrospectively analyzed 45 ARDS children with hematological neoplasms who were admitted to the PICU of Shanghai Children's Medical Center from January 1, 2014, to December 31, 2020. The 45 children were divided into a survival group and a non-survival group, a pulmonary ARDS group and an exogenous pulmonary ARDS group, and an agranulocytosis group and a non-agranulocytosis group, for statistical analysis. The main clinical manifestations were fever, cough, progressive dyspnea, and hypoxemia; 55.6% (25/45) of the children had multiple organ dysfunction syndrome (MODS). The overall mortality rate was 55.6% (25/45). The vasoactive inotropic score (VIS), pediatric critical illness scoring (PCIS), average fluid volume in the first 3 days and the first 7 days, and the incidence of MODS in the non-survival group were all significantly higher than those in the survival group (P < 0.05). However, total length of mechanical ventilation and length of hospital stay and PICU days in the non-survival group were significantly lower than those in the survival group (P < 0.05). The PCIS (OR = 0.832, P = 0.004) and the average fluid volume in the first 3 days (OR = 1.092, P = 0.025) were independent risk factors for predicting death. Children with exogenous pulmonary ARDS were more likely to have MODS than pulmonary ARDS (P < 0.05). The mean values of VIS, C-reactive protein (CRP), and procalcitonin (PCT) in children with exogenous pulmonary ARDS were also higher (P < 0.05). After multivariate analysis, PCT was independently related to exogenous pulmonary ARDS. The total length of hospital stay, peak inspiratory pressure (PIP), VIS, CRP, and PCT in the agranulocytosis group were significantly higher than those in the non-agranulocytosis group (P < 0.05). Last, CRP and PIP were independently related to agranulocytosis. In conclusion, children with hematological neoplasms complicated with ARDS had a high overall mortality and poor prognosis. Children complicated with MODS, positive fluid balance, and high VIS and PCIS scores were positively correlated with mortality. In particular, PCIS score and average fluid volume in the first 3 days were independent risk factors for predicting death. Children with exogenous pulmonary ARDS and children with agranulocytosis were in a severely infected status and more critically ill.

Incidence Density Rate of Neonatal Mortality and Predictors in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

Background

Neonatal mortality in Sub-Saharan countries is remarkably high. Though there are inconsistent studies about the incidence density rate of neonatal mortalities (IDR) and predictors in Sub-Saharan Africa, they are inconclusive to policymakers and program planners. In this study, the IDR of neonatal mortalities and predictors was determined.

Methods

Electronic databases (Web of Science, PubMed, EMBASE (Elsevier), Scopus, CINAHL (EBSCOhost), World Cat, Google Scholar, and Google) were explored. 20 out of 818 studies were included in this study. The IDRs and predictors of neonatal mortality were computed from studies conducted in survival analysis. Fixed and random effect models were used to compute pooled estimates. Subgroup and sensitivity analyses were performed.

Results

Neonates were followed for a total of 1,095,611 neonate-days; 67142 neonate-days for neonates treated in neonatal intensive care units and 1,028,469 neonate-days for community-based studies. The IDRs of neonatal mortalities in neonatal intensive care units and in the community were 24.53 and 1.21 per 1000 person-days, respectively. The IDRs of early and late neonatal mortalities neonatal intensive care units were 22.51 and 5.09 per 1000 neonate-days, respectively. Likewise, the IDRs of early and late neonatal mortalities in the community were 0.85 and 0.31, respectively. Not initiating breastfeeding within one hour, multiple births, rural residence, maternal illness, low Apgar score, being preterm, sepsis, asphyxia, and respiratory distress syndrome were independent predictors of time to neonatal mortality in neonatal intensive care units and male gender, perceived small size, multiple births, and ANC were predictors of neonatal mortality in the community.

Conclusion

The incidence density rate of neonatal mortality in Sub-Saharan Africa is significantly high. Multiple factors (neonatal and maternal) were found to be independent predictors. Strategies must be designed to address these predictors, and prospective studies could reveal other possible factors of neonatal mortalities.

Investigation of anti-inflammatory effects of oxygen nanobubbles in a rat hydrochloric acid lung injury model

Aim: To investigate the anti-inflammatory effect of oxygen nanobubbles (ONBs) in an acute lung injury rat model. Materials & methods: In a rat hydrochloric acid lung injury model, ONB fluid was administered intravenously in the ONB group (n = 6) and normal saline was administered in the control group (n = 6). 4 h later, arterial partial pressure of oxygen (PaO₂), mean arterial pressure and plasma inflammatory cytokines were measured. Results: There were no significant differences in the PaO₂, mean arterial pressure or TNF-α and IL-6 levels between the two groups. Conclusions: No anti-inflammatory effect could be confirmed at the present ONB dose in the rat model of acute lung injury.

Glycyrrhetinic acid alleviates acute lung injury by PI3K/AKT suppressing macrophagic Nlrp3 inflammasome activation

Glycyrrhetinic acid (GA), a triterpene saponins, has been widely proven to have multiple medicinal properties. Our study aimed to figure out the protective effect of GA on acute lung injury (ALI) and the underlying mechanism. The LPS-induced ALI model mice were intratracheally administrated with 10 mg/kg LPS. Pretreatment with GA (10, 20, 40 mg/kg, i.g.) ameliorated acute lung injury pathological damage, macrophage infiltration and lung edema. In the lung tissue, immunofluorescence (IF) and Immunohistochemistry (IHC) were performed to detect macrophage Nod-like receptor 3 (Nlrp3) inflammasome activation and interleukin-1β (IL-1β) protein expression. In macrophages, the co-localization of Nlrp3 with caspase-1 and Nlrp3 with ASC were assessed by IF. The translational and transcriptional level of Nlrp3, cle-caspase-1 and apoptosis-associated speck-like protein containing CARD (ASC), were examined by Western blot and Real time PCR (RT-PCR). The protein expression of Cle-caspase-1 was remarkably suppressed via sh-Nlrp3 transfection compared with LPS groups. GA notably attenuated ALI by inhibiting Nlrp3 formation and activation. Furthermore, GA downregulated the production of reactive oxygen species (ROS) and the phosphorylation level of PI3K and AKT in macrophages. These findings indicate that GA ameliorated ALI in mice by suppressing the activation of Nlrp3 inflammasome which may be mediated by ROS-PI3K/AKT pathway. GA may serve as a promising agent for the attenuation of ALI-related inflammation and pathology.

<p>Third-Day Oxygenation Index is an Excellent Predictor of Survival in Children Mechanically Ventilated for Acute Respiratory Distress Syndrome</p>

Purpose

The aim of this study was to assess the association between oxygenation index (OI) and outcome in children with acute respiratory distress syndrome (ARDS).

Patients and Methods

Patients (age, >30 days) in the pediatric intensive care unit from April 2011 to March 2016 with ARDS and who were mechanically ventilated were included. Patients were divided into two age groups: infants (<12month) and older children. Lowest PaO₂/FiO₂ and SpO₂/FiO₂ ratios and highest mean airway pressure (MAP) were recorded on the first day of ARDS and after 72 h. OI was calculated on the first and third days of mechanical ventilation (MV) and its association with OI (first and third days) and short-term mortality evaluated at 28 days.

Results

MV was initiated a mean of 2.3 days after admission (median, 1.0 day; maximum 14 days). The average MV duration for all patients was 11.8 (median, 7.0) days. Mean (95% confidence interval (CI)) OI values on the first day of MV were 14.17 (11.94–16.41), 12.72 (10.68–14.75), and 13.24 (11.73–14.74) for infants, older children, and all participants, respectively. In survivors (n=39) mean OI was 11.66 (9.64–13.68) compared with 15.22 (13.03–17.40) in non-survivors (n=31). Logistic regression analysis revealed that OI on day 3 had highly significant prognostic value for mortality (odds ratio, 256.5, 95% CI 27.1–2424, p<0.001), with an AUC of 0.919 (cut-off value, 17; positive predictive value, 0.905; negative predictive value, 0.964; p=0.0001). In contrast, OI on day 1 did not have significant prognostic value (AUC, 0.634; p=0.056) for short-term mortality. Different modes of MV were not significantly associated with outcome (p>0.05).

Conclusion

OI is a simple, highly accurate, and sensitive predictor of the survival (short-term mortality) of children mechanically ventilated for ARDS.

Placenta‑derived mesenchymal stem cells ameliorate lipopolysaccharide‑induced inflammation in RAW264.7 cells and acute lung injury in rats

Acute lung injury (ALI) is a severe lung syndrome with high morbidity and mortality, due to its complex mechanism and lack of effective therapy. The use of placenta-derived mesenchymal stem cells (pMSCs) has provided novel insight into treatment options of ALI. The effects of pMSCs on lipopolysaccharide (LPS)-induced inflammation were studied using a co-culture protocol with LPS-stimulated RAW264.7 cells. An LPS-induced ALI Sprague-Dawley rat model was developed by intravenously injecting 7.5 mg/kg LPS, and intratracheal instillation of 1×10⁵ pMSCs was performed after administration of LPS to investigate the therapeutic potential of these cells. pMSCs ameliorated LPS-induced ALI, as suggested by downregulated pro-inflammatory cytokine tumor necrosis factor-α and increased anti-inflammatory cytokine interleukin-10 in both cell and animal models. Moreover, the protein and leukocyte cells in bronchoalveolar lavage fluid decreased at a rapid rate after treatment with pMSCs. Histopathology demonstrated that pMSCs alleviated the infiltration of inflammatory cells, pulmonary hyperemia and hemorrhage, and interstitial edema. In addition, pMSC reduced the LPS-induced expression of C-X-C motif chemokine ligand 12 in RAW264.7 macrophages and in lung tissue of ALI rats. This demonstrated that pMSCs are therapeutically effective in LPS-induced ALI.

Outcomes of Severe PARDS on High-Frequency Oscillatory Ventilation - A Single Centre Experience

OBJECTIVE

To describe experience with high-frequency oscillatory ventilation (HFOV) in children with acute respiratory distress syndrome (ARDS) transitioned from conventional mechanical ventilation (CMV) due to refractory hypoxemia and to assess factors associated with survival and also compare outcomes of patients who were managed with early HFOV (within 24 h of intubation) vs. late HFOV.

METHODS

This retrospective, observational study was conducted in a tertiary care hospital's pediatric intensive care unit. Thirty-four children with pediatric acute respiratory distress syndrome (PARDS) managed with HFOV were included.

RESULTS

Of 34 children with PARDS managed with HFOV after failure of conventional ventilation to improve oxygenation, 8 survived. Improvement in the Oxygenation Index (OI) at 48 h of initiation of HFOV along with percent increase in PaO₂/FiO₂ (P/F ratio) at 24 h of HFOV were predictors of survival. The response to HFOV, based on OI and P/F ratio, between 24 and 48 h of ventilation identified potential survivors. Also, lower positive end-expiratory pressure (PEEP) on CMV and shorter duration of CMV before initiation of HFOV were associated with survival.

CONCLUSIONS

Survival in pediatric ARDS patients treated with HFOV could be predicted by using trends of OI - with survivors showing a more rapid decline in OI between 24 and 48 h of initiation compared to non-survivors.

Improved oxygenation following methylprednisolone therapy and survival in paediatric acute respiratory distress syndrome

Background

Methylprednisolone remains a commonly used ancillary therapy for paediatric acute respiratory distress syndrome (PARDS), despite a lack of level 1 evidence to justify its use. When planning prospective trials it is useful to define response to therapy and to identify if there is differential response in certain patients, i.e. existence of ‘responders’ and ‘non responders’ to therapy. This retrospective, observational study carried out in 2 tertiary referral paediatric intensive care units aims to characterize the change in Oxygen Saturation Index, following the administration of low dose methylprednisolone in a cohort of patients with PARDS, to identify what proportion of children treated demonstrated response, whether any particular characteristics predict response to therapy, and to determine if a positive response to corticosteroids is associated with reduced Paediatric Intensive Care Unit mortality.

Methods

All patients who received prolonged, low dose, IV methylprednisolone for the specific indication of PARDS over a 5-year period (2011–2016) who met the PALICC criteria for PARDS at the time of commencement of steroid were included (n = 78).OSI was calculated four times per day from admission until discharge from PICU (or death). Patients with ≥20% improvement in their mean daily OSI within 72 hours of commencement of methylprednisolone were classified as ‘responders’. Primary outcome measure was survival to PICU discharge.

Results

Mean OSI of the cohort increased until the day of steroid commencement then improved thereafter. 59% of patients demonstrated a response to steroids. Baseline characteristics were similar between responders and non-responders. Survival to PICU discharge was significantly higher in ‘responders’ (74% vs 41% OR 4.14(1.57–10.87) p = 0.004). On multivariable analysis using likely confounders, response to steroid was an independent predictor of survival to PICU discharge (p = 0.002). Non-responders died earlier after steroid administration than responders (p = 0.003).

Conclusions

An improvement in OSI was observed in 60% of patients following initiation of low dose methylprednisolone therapy in this cohort of patients with PARDS. Baseline characteristics fail to demonstrate a difference between responders and non-responders. A 20% improvement in OSI after commencement of methylprednisolone was independently predictive of survival, Prospective trials are needed to establish if there is a benefit from this therapy.

Synthetic surfactant with a recombinant surfactant protein C analogue improves lung function and attenuates inflammation in a model of acute respiratory distress syndrome in adult rabbits

AIM

In acute respiratory distress syndrome (ARDS) damaged alveolar epithelium, leakage of plasma proteins into the alveolar space and inactivation of pulmonary surfactant lead to respiratory dysfunction. Lung function could potentially be restored with exogenous surfactant therapy, but clinical trials have so far been disappointing. These negative results may be explained by inactivation and/or too low doses of the administered surfactant. Surfactant based on a recombinant surfactant protein C analogue (rSP-C33Leu) is easy to produce and in this study we compared its effects on lung function and inflammation with a commercial surfactant preparation in an adult rabbit model of ARDS.

METHODS

ARDS was induced in adult New Zealand rabbits by mild lung-lavages followed by injurious ventilation (V_T 20 m/kg body weight) until P/F ratio < 26.7 kPa. The animals were treated with two intratracheal boluses of 2.5 mL/kg of 2% rSP-C33Leu in DPPC/egg PC/POPG, 50:40:10 or poractant alfa (Curosurf®), both surfactants containing 80 mg phospholipids/mL, or air as control. The animals were subsequently ventilated (V_T 8-9 m/kg body weight) for an additional 3 h and lung function parameters were recorded. Histological appearance of the lungs, degree of lung oedema and levels of the cytokines TNFα IL-6 and IL-8 in lung homogenates were evaluated.

RESULTS

Both surfactant preparations improved lung function vs. the control group and also reduced inflammation scores, production of pro-inflammatory cytokines, and formation of lung oedema to similar degrees. Poractant alfa improved compliance at 1 h, P/F ratio and PaO₂ at 1.5 h compared to rSP-C33Leu surfactant.

CONCLUSION

This study indicates that treatment of experimental ARDS with synthetic lung surfactant based on rSP-C33Leu improves lung function and attenuates inflammation.

Pertinent clinical outcomes in pediatric survivors of pediatric acute respiratory distress syndrome (PARDS): a narrative review

The objectives of this review are to describe the limitations of commonly used clinical outcomes [e.g., mortality, ventilation parameters, need for extracorporeal membrane oxygenation (ECMO), pediatric intensive care unit (PICU) and hospital length of stay (LOS)] in pediatric acute respiratory distress syndrome (PARDS) studies; and to explore other pertinent clinical outcomes that pediatric critical care practitioners should consider in future clinical practice and research studies. These include long-term pulmonary function, risk of pulmonary hypertension (PHT), nutrition status and growth, PICU-acquired weakness, neurological outcomes and neurocognitive development, functional status, health-related quality of life (HRQOL)], health-care costs, caregiver and family stress. PubMed was searched using the following keywords or medical subject headings (MESH): "acute lung injury (ALI)", "acute respiratory distress syndrome (ARDS)", "pediatric acute respiratory distress syndrome (PARDS)", "acute hypoxemia respiratory failure", "outcomes", "pediatric intensive care unit (PICU)", "lung function", "pulmonary hypertension", "growth", "nutrition', "steroid", "PICU-acquired weakness", "functional status scale", "neurocognitive", "psychology", "health-care expenditure", and "HRQOL". The concept of contemporary measure outcomes was adapted from adult ARDS long-term outcome studies. Articles were initially searched from existing PARDS articles pool. If the relevant measure outcomes were not found, where appropriate, we considered studies from non-ARDS patients within the PICU in whom these outcomes were studied. Long-term outcomes in survivors of PARDS were not follow-up in majority of pediatric studies regardless of whether the new or old definitions of ARDS in children were used. Relevant studies were scarce, and the number of participants was small. As such, available studies were not able to provide conclusive answers to most of our clinical queries. There remains a paucity of data on contemporary clinical outcomes in PARDS studies. In addition to the current commonly used outcomes, clinical researchers and investigators should consider examining these contemporary outcome measures in PARDS studies in the future.

The role of point-of-care ultrasound in pediatric acute respiratory distress syndrome: emerging evidence for its use

Pediatric acute respiratory distress syndrome (PARDS) remains an important cause of significant morbidity and mortality. The 2015 PALICC definition of PARDS requires chest imaging to diagnose the presence of new pulmonary infiltrate(s). Traditionally chest radiography or computerised tomography have been used. However, these carry the limitations of exposure to ionizing radiation, need to transfer the critically unwell child, lag-time with clinical correlation and lack of immediate results. The use of point of care ultrasound (POCUS) has been well established in adult emergency medicine and critical care. Furthermore, the adult literature clearly demonstrates that lung POCUS is a safe and validated tool, which is highly sensitive and specific when compared to chest radiography for differentiating the causes of respiratory failure, including ARDS. Whilst pediatric specific data is limited, it has been shown that the signs seen in adults are reproducible in critically ill neonates and children. Furthermore, the numerous benefits of POCUS in the paediatric setting are compelling and include lack of ionizing radiation, immediate feedback, promoting time at the bedside of the critically unwell child, and ease of serial assessments. This review article presents the emerging evidence demonstrating that lung POCUS can be used not only to support the diagnosis of pediatric ARDS, but also to assess for complications, monitor progression and thus guide management. We hope it will stimulate much needed collaborative research into this exciting field of imaging and its applications to PARDS and beyond.

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.