High-flow oxygen therapy in moderate to severe bronchiolitis: a randomised controlled trial

Severe respiratory syncytial virus disease

The burden of respiratory syncytial virus (RSV) disease is widely recognized. Main risk factors for severe disease, such as extreme ages, chronic cardiopulmonary conditions, and immunosuppression, typically coincide with poorer outcomes. While the majority of RSV hospitalizations involve healthy children, a higher proportion of hospitalized adults with underlying conditions need intensive care. Presently, treatment primarily consists of supportive measures. RSV-induced wheezing should be distinguished from respiratory tract thickening, without response to bronchodilators. Obstructive RSV disease frequently overlaps with viral pneumonia. Non-invasive mechanical ventilation and high-flow oxygen therapy represented significant advancements in the management of severe RSV disease in children and may also hold considerable importance in specific phenotypes of RSV disease in adults. Most severe infections manifest with refractory hypoxemia necessitating more advanced ventilatory support and/or extracorporeal membrane oxygenation therapy. Although bacterial co-infection rates are low, they have been associated with worse outcomes. Antibiotic prescription rates are high. Accurately diagnosing bacterial co-infections remains a challenge. Current evidence and antibiotic stewardship policies advise against indiscriminate antibiotic usage, even in severe cases. The role of currently developing antiviral therapies in severe RSV disease will be elucidated in the coming years, contingent upon the success of new vaccines and immune passive strategies involving nirsevimab.

Severe respiratory syncytial virus infection in children: burden, management, and emerging therapies

The global burden of respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) in young children is high. The RSV prevention strategies approved in 2023 will be essential to lowering the global disease burden. In this Series paper, we describe clinical presentation, burden of disease, hospital management, emerging therapies, and targeted prevention focusing on developments and groundbreaking publications for RSV. We conducted a systematic search for literature published in the past 15 years and used a non-systematic approach to analyse the results, prioritising important papers and the most recent reviews per subtopic. Annually, 33 million episodes of RSV LRTI occur in children younger than 5 years, resulting in 3·6 million hospitalisations and 118 200 deaths. RSV LRTI is a clinical diagnosis but a clinical case definition and universal clinical tool to predict severe disease are non-existent. The advent of molecular point-of-care testing allows rapid and accurate confirmation of RSV infection and could reduce antibiotic use. There is no evidence-based treatment of RSV, only supportive care. Despite widespread use, evidence for high-flow nasal cannula (HFNC) therapy is insufficient and increased paediatric intensive care admissions and intubation indicate the need to remove HFNC therapy from standard care. RSV is now a vaccine-preventable disease in young children with a market-approved long-acting monoclonal antibody and a maternal vaccine targeting the RSV prefusion protein. To have a high impact on life-threatening RSV infection, infants at high risk, especially in low-income and middle-income countries, should be prioritised as an interim strategy towards universal immunisation. The implementation of RSV preventive strategies will clarify the full burden of RSV infection. Vaccine probe studies can address existing knowledge gaps including the effect of RSV prevention on transmission dynamics, antibiotic misuse, the respiratory microbiome composition, and long-term sequalae.

Normal saline for children with bronchiolitis: study protocol for a randomised controlled non-inferiority trial

INTRODUCTION

Bronchiolitis is one of the most common reasons for hospital admissions in early childhood. As supportive treatment, some treatment guidelines suggest using nasal irrigation with normal saline (NS) to facilitate clearance of mucus from the airways. In addition, most paediatric departments in Denmark use nebulised NS for the same purpose, which can mainly be administered as inpatient care. However, no studies have ever directly tested the effect of saline in children with bronchiolitis.

METHODS AND ANALYSIS

The study is an investigator-initiated, multicentre, open-label, randomised, controlled non-inferiority trial and will be performed at six paediatric departments in eastern Denmark. We plan to include 300 children aged 0-12 months admitted to hospital with bronchiolitis. Participating children are randomised 1:1:1 to nebulised NS, nasal irrigation with NS or no saline therapy. All other treatment will be given according to standard guidelines.The primary outcome is duration of hospitalisation, analysed according to intention-to-treat analysis using linear regression and Cox regression analysis. By including at least 249 children, we can prove non-inferiority with a limit of 12 hours admission, alpha 2.5% and a power of 80%. Secondary outcomes are need for respiratory support with nasal continuous positive airway pressure or high-flow oxygen therapy and requirement of fluid supplements (either by nasogastric tube or intravenous).

ETHICS AND DISSEMINATION

This study may inform current practice for supportive treatment of children with bronchiolitis. First, if NS is found to be helpful, it may be implemented into global guidelines. If no effect of NS is found, we can stop spending resources on an ineffective treatment. Second, if NS is effective, but nasal irrigation is non-inferior to nebulisation, it may reduce the workload of nurses, and possible duration of hospitalisation because the treatment can be delivered by the parents at home.

TRIAL REGISTRATION NUMBER

NCT05902702.

Hyperoxia can Induce Lung Injury by Upregulating AECII Autophagy and Apoptosis Via the mTOR Pathway

Oxygen therapy is a crucial medical intervention, but it is undeniable that it can lead to lung damage. The mTOR pathway plays a pivotal role in governing cell survival, including autophagy and apoptosis, two phenomena deeply entwined with the evolution of diseases. However, it is unclarified whether the mTOR pathway is involved in hyperoxic acute lung injury (HALI). The current study aims to clarify the molecular mechanism underlying the pathogenesis of HALI by constructing in vitro and in vivo models using H2O2 and hyperoxia exposure, respectively. To investigate the role of mTOR, the experiment was divided into five groups, including normal group, injury group, mTOR inhibitor group, mTOR activator group, and DMSO control group. Western blotting, Autophagy double labeling, TUNEL staining, and HE staining were applied to evaluate protein expression, autophagy activity, cell apoptosis, and pathological changes in lung tissues. Our data revealed that hyperoxia can induce autophagy and apoptosis in Type II alveolar epithelial cell (AECII) isolated from the treated rats, as well as injuries in the rat lung tissues; also, H2O2 stimulation increased autophagy and apoptosis in MLE-12 cells. Noticeably, the experiments performed in both in vitro and in vivo models proved that the mTOR inhibitor Rapamycin (Rapa) functioned synergistically with hyperoxia or H2O2 to promote AECII autophagy, which led to increased apoptosis and exacerbated lung injury. On the contrary, activation of mTOR with MHY1485 suppressed autophagy activity, consequently resulting in reduced apoptosis and lung injury in H2O2-challenged MLE-12 cells and hyperoxia-exposed rats. In conclusion, hyperoxia caused lung injury via mTOR-mediated AECII autophagy.

Effect Modifiers of the Association of High-Flow Nasal Cannula and Bronchiolitis Length of Stay

BACKGROUND AND OBJECTIVES

High-flow nasal cannula (HFNC) therapy for hospitalized children with bronchiolitis is associated with a longer length of stay (LOS) when used outside of the ICU. We sought to explore the association between HFNC and LOS to identify if demographic and clinical factors may modify the effect of HFNC usage on LOS.

METHODS

In this multicenter retrospective cohort study, we used a combination of hospital records and the Pediatric Health Information System. We included encounters from September 1, 2018 to March 31, 2020 for patients <2 years old diagnosed with bronchiolitis. Multivariable Poisson regression was performed for the association of LOS with measured covariates, including fixed main effects and interaction terms between HFNC and other factors.

RESULTS

Of 8060 included patients, 2179 (27.0%) received HFNC during admission. Age group, weight, complex chronic condition, initial tachypnea, initial desaturation, and ICU services were significantly associated with LOS. The effect of HFNC on LOS differed among hospitals (P < .001), with the estimated increase in LOS ranging from 32% to 139%. The effect of HFNC on LOS was modified by age group, initial desaturation, and ICU services, with 1- to 6-month-old infants, patients without initial desaturation, and patients without ICU services having the highest association between HFNC and LOS, respectively.

CONCLUSIONS

We identified multiple potential effect modifiers for the relationship between HFNC and LOS. The authors of future prospective studies should investigate the effect of HFNC usage on LOS in non-ICU patients without documented desaturation.

Nasal CPAP in the Pediatric Ward to Reduce PICU Admissions for Severe Bronchiolitis?

In treating acute bronchiolitis in infants, the decision to use continuous positive airway pressure (CPAP) often involves infant referral from the pediatric ward to the pediatric intensive care unit (PICU). We present our experience of CPAP use in a general pediatric ward, aiming to reduce the pressure on the PICU in recent outbreaks of bronchiolitis. Clinical data of patients less than 12 months of age and admitted for bronchiolitis from 1 October 2021 to 31 March 2023 were retrospectively collected. Of 82 infants admitted for bronchiolitis, 16 (19%) were treated with nasal CPAP (nCPAP group); of the remaining 66, 21 (26%) were treated with a low-flow nasal cannula (LFNC) only, 1 (1%) was also treated a with high-flow nasal cannula (HFNC), 12 (15%) were treated with an HFNC only, and 41 (50%) were treated without oxygen support (no-nCPAP group). Overall, coinfection with RSV and SARS-CoV-2 was observed in three patients and SARS-CoV-2 infection was observed in two patients. None of them required any type of oxygen support. Only 3/16 (19%) infants in the nCPAP group were referred to the PICU due to worsening clinical conditions despite nCPAP support. In our experience of treating epidemic bronchiolitis, nCPAP can be safely managed in a general pediatric ward, thus reducing the burden of admissions to the PICU. Training and regular updating of the pediatric staff, careful monitoring of the patient, and close cooperation with the PICU were instrumental for our team.