Respiratory syncytial virus-induced paediatric ARDS: why we should unpack the syndrome

The Local and Systemic Exposure to Oxygen in Children With Severe Bronchiolitis on Invasive Mechanical Ventilation: A Retrospective Cohort Study

OBJECTIVES

Oxygen supplementation is a cornerstone treatment in critically ill children with bronchiolitis in the PICU. However, potential deleterious effects of high-dose oxygen are well-known. In this study, we aim to describe the pulmonary (local) and arterial (systemic) oxygen exposure over the duration of invasive mechanical ventilation (IMV) in children with severe bronchiolitis. Our secondary aim was to estimate potentially avoidable exposure to high-dose oxygen in these patients.

DESIGN

Retrospective cohort study.

SETTING

Single-center, tertiary-care PICU.

PATIENTS

Children younger than 2 years old admitted to the PICU for severe bronchiolitis receiving IMV.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hourly measurements of Fio2 and peripheral oxygen saturation (Spo2), and arterial blood gas data were collected up to day 10 of IMV. A total of 24,451 hours of IMV were observed in 176 patients (median age of 1.0 mo [interquartile range (IQR), 1.0-2.3 mo]). The pulmonary exposure to oxygen was highest during the first day of IMV (median time-weighted average [TWA]-Fio2 0.46 [IQR, 0.39-0.53]), which significantly decreased over subsequent days. The systemic exposure to oxygen was relatively low, as severe hyperoxemia (TWA-Pao2 > 248 Torr [> 33 kPa]) was not observed. However, overuse of oxygen was common with 52.3% of patients (n = 92) having at least 1 day of possible excessive oxygen exposure and 14.8% (n = 26) with severe exposure. Furthermore, higher oxygen dosages correlated with increasing overuse of oxygen (rrepeated measures, 0.59; 95% CI, 0.54-0.63). Additionally, caregivers were likely to keep Fio2 greater than or equal to 0.50 when Spo2 greater than or equal to 97%.

CONCLUSIONS

Moderate to high-dose pulmonary oxygen exposure and potential overuse of oxygen were common in this cohort of severe bronchiolitis patients requiring IMV; however, this was not accompanied by a high systemic oxygen burden. Further studies are needed to determine optimal oxygenation targets to prevent overzealous use of oxygen in this vulnerable population.

Sivelestat improves clinical outcomes and decreases ventilator-associated lung injury in children with acute respiratory distress syndrome: a retrospective cohort study

BACKGROUND

Sivelestat, a neutrophil elastase inhibitor, is a selective and targeted therapy for acute respiratory distress syndrome (ARDS) in adults; and it is also reported to apply to children with ARDS. However, there is little evidence of its efficacy in children.

METHODS

This study recruited 212 patients ranging in age from 28 days to 18 years old, and who met the diagnostic criteria for pediatric ARDS (PARDS) while hospitalized in the Intensive Care Department of the Affiliated Children's Hospital of Xi'an Jiaotong University. A total of 125 patients (case group) received sivelestat treatment, and 87 were assigned to the control group. There were no significant differences in gender (P=0.445) or age (P=0.521). Control group data were collected from the Electronic Case Information System for pediatric patients diagnosed with ARDS between March 2017 to January 2020. Data for the case group were collected from the Electronic Case Information System between February 2020 to February 2022. Demographic data, clinically relevant indicators, respiratory parameters were recorded. The 28-day mortality was the primary endpoint; the Kaplan-Meier and log-rank tests were used to evaluate cumulative survival rate.

RESULTS

For general demographic and clinical characteristics, no significant differences were observed between the two groups. Compared to the control group, the case group displayed significant improvements in PaO₂/FiO₂ at 48 h (141±45 vs. 115±21, P<0.001) and 72 h (169±61 vs. 139±40, P<0.001) post-admission, and plateau pressure was lower than that in the control group at 24 h (24±3 vs. 28±7, P<0.001), 48 h (21±4 vs. 26±7, P<0.001), and 72 h (20±2 vs. 25±6, P<0.001) post-admission. Interleukin-8 levels were lower in the case group at 48 and 72 h post-admission. Overall, 28-day mortality was 25.47% (54/212). Twenty-five children died in the sivelestat group, 29 children died in the control group. Survival analysis revealed that cumulative survival in the case group was higher than that in the control group (P=0.028).

CONCLUSIONS

ARDS is expected to have high morbidity and mortality in critical care medicine, and precise targeted drugs are lacking. Our study showed that sivelestat improved prognosis and reduces mortality in children with ARDS.

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.

Identification of transcriptional regulatory network associated with response of host epithelial cells to SARS-CoV-2

Identification of transcriptional regulatory mechanisms and signaling networks involved in the response of host cells to infection by SARS-CoV-2 is a powerful approach that provides a systems biology view of gene expression programs involved in COVID-19 and may enable the identification of novel therapeutic targets and strategies to mitigate the impact of this disease. In this study, our goal was to identify a transcriptional regulatory network that is associated with gene expression changes between samples infected by SARS-CoV-2 and those that are infected by other respiratory viruses to narrow the results on those enriched or specific to SARS-CoV-2. We combined a series of recently developed computational tools to identify transcriptional regulatory mechanisms involved in the response of epithelial cells to infection by SARS-CoV-2, and particularly regulatory mechanisms that are specific to this virus when compared to other viruses. In addition, using network-guided analyses, we identified kinases associated with this network. The results identified pathways associated with regulation of inflammation (MAPK14) and immunity (BTK, MBX) that may contribute to exacerbate organ damage linked with complications of COVID-19. The regulatory network identified herein reflects a combination of known hits and novel candidate pathways supporting the novel computational pipeline presented herein to quickly narrow down promising avenues of investigation when facing an emerging and novel disease such as COVID-19.

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.

Cellular Therapy for the Treatment of Paediatric Respiratory Disease

Respiratory disease is the leading cause of death in children under the age of 5 years old. Currently available treatments for paediatric respiratory diseases including bronchopulmonary dysplasia, asthma, cystic fibrosis and interstitial lung disease may ameliorate symptoms but do not offer a cure. Cellular therapy may offer a potential cure for these diseases, preventing disease progression into adulthood. Induced pluripotent stem cells, mesenchymal stromal cells and their secretome have shown great potential in preclinical models of lung disease, targeting the major pathological features of the disease. Current research and clinical trials are focused on the adult population. For cellular therapies to progress from preclinical studies to use in the clinic, optimal cell type dosage and delivery methods need to be established and confirmed. Direct delivery of these therapies to the lung as aerosols would allow for lower doses with a higher target efficiency whilst avoiding potential effect of systemic delivery. There is a clear need for research to progress into the clinic for the treatment of paediatric respiratory disease. Whilst research in the adult population forms a basis for the paediatric population, varying disease pathology and anatomical differences in paediatric patients means a paediatric-centric approach must be taken.

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

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

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.