High-Flow Nasal Cannula Use for Respiratory Support Outside the Paediatric Intensive Care Unit in Children Over 1 Year: A Narrative Review.

AIMS: High-flow nasal cannula (HFNC) therapy is increasingly used outside paediatric intensive care units (PICUs) for children with acute respiratory distress, despite limited evidence beyond bronchiolitis and neonatal populations. No existing review has synthesised evidence in children over 1 year without bronchiolitis managed in emergency department and ward settings. This narrative review aims to address this gap. METHODS: PubMed, Scopus and Medline (OVID) were searched to October 2025 for studies of HFNC in children aged over 12 months with acute respiratory distress, managed in emergency department or ward settings and compared with conventional oxygen therapy or non-invasive ventilation. RESULTS: Eight studies (six randomised trials, one pilot RCT, one observational cohort) were included, covering asthma, pneumonia and mixed hypoxaemic respiratory failure. Small trials showed early physiological improvement without consistent benefit in length of stay or PICU admission. Flow rates were highly variable, with several studies delivering flow below thresholds considered necessary for a true high-flow effect. The largest trial reported longer hospital stay and higher PICU admission with early HFNC use compared to conventional oxygen therapy. CONCLUSION: Overall, while HFNC appears safe and well tolerated, current evidence does not support routine first-line use outside the PICU in children over 1 year. More prospective research is urgently needed to identify which populations will benefit from HFNC use. Until such data is available, HFNC should be implemented with clear institutional guidelines, defined escalation criteria and close clinical monitoring.