High-flow nasal cannula (HFNC) therapy has become more common outside paediatric intensive care units (PICUs) for children presenting with acute respiratory distress. Most prior research has focused on bronchiolitis or neonatal populations, leaving uncertainty about HFNC effectiveness in older children managed in emergency departments and ward settings. This narrative review specifically targeted children older than 12 months without bronchiolitis to synthesise available evidence for HFNC use outside the PICU.
The authors performed a structured search of PubMed, Scopus and Medline (OVID) through October 2025 to identify studies of HFNC in children aged over 12 months with acute respiratory distress. The review included studies where HFNC was used in emergency department or ward settings and compared with conventional oxygen therapy or non-invasive ventilation. Study designs that met inclusion criteria comprised randomised controlled trials, a pilot randomised controlled trial and observational cohort data.
Eight studies met the inclusion criteria: six randomised trials, one pilot RCT and one observational cohort. The clinical conditions represented across these studies included asthma, pneumonia and mixed hypoxaemic respiratory failure. Importantly, the included population deliberately excluded bronchiolitis and neonatal cohorts, focusing on older paediatric patients managed outside PICU environments.
Across the small trials, HFNC produced some early physiological improvements. However, the review highlights substantial heterogeneity in the flow rates applied in the included studies. Several studies delivered flows below levels regarded in the literature as necessary to generate the characteristic physiological effects attributed to HFNC (for example, reduction of work of breathing, washout of dead space and provision of positive distending pressure). This variability in delivered flow raises uncertainty about whether observed benefits reflect true high-flow physiology or represent effects of warmed, humidified oxygen at lower flow.
Clinical outcome data were inconsistent across studies. While small trials reported early physiological gains, these did not translate into consistent reductions in hospital length of stay or PICU admissions. Notably, the largest trial included in the review found that early use of HFNC—compared with conventional oxygen therapy—was associated with a longer hospital stay and a higher rate of PICU admission. Thus, evidence from randomized and observational data does not uniformly support improved downstream clinical outcomes with routine early HFNC use outside the PICU in children over 1 year.
The review reports that HFNC appeared to be safe and generally well tolerated in the included studies. Despite acceptable safety signals, the authors caution against routine first-line HFNC use outside PICU without institutional safeguards. They recommend that HFNC implementation in emergency department and ward settings should be accompanied by clear local guidelines, predefined escalation criteria and arrangements for close clinical monitoring to detect early deterioration and ensure timely transfer to higher-acuity care if required.
The authors conclude that current evidence does not support routine first-line use of HFNC outside the PICU for children older than 12 months with acute respiratory distress. Although HFNC can yield early physiological improvement, trials have not consistently demonstrated benefit for key clinical endpoints such as length of stay or avoidance of PICU admission. Given the heterogeneity in flow settings and mixed outcome data—plus the largest trial indicating potential for harm in terms of longer admission and increased PICU transfer—the authors advise cautious, protocolised use rather than broad adoption as first-line therapy.
The review emphasises urgent need for further prospective research to identify which patient subgroups may derive net benefit from HFNC in emergency department and ward environments. Questions highlighted include the appropriate flow thresholds required to achieve high-flow physiological effects in different age and disease groups, which diagnoses or severities of respiratory distress respond favorably, and how HFNC compares with other oxygen and non-invasive ventilation strategies for meaningful clinical outcomes. Until such data are available, institution-level governance, explicit escalation criteria and vigilant monitoring should underpin any HFNC use outside PICU for children over 1 year.
This summary is based on the abstract and information provided in the cited narrative review. Details such as individual trial sample sizes, precise flow settings in each study, statistical measures and full reference list were reported in the source review but are not reproduced here in full. For trial-level data and the complete reference set consult the original article (J Paediatr Child Health; DOI: 10.1111/jpc.70572).