Respiratory Support in Bronchiolitis: A Narrative Review of the Evidence for and Against High-Flow Nasal Cannula (HFNC) Use

Bronchiolitis is a leading cause of pediatric hospitalization, and the use of high-flow nasal cannula (HFNC) as respiratory support has increased substantially over the past decade despite ongoing uncertainty about its clinical benefits. This narrative review evaluates the evidence supporting and questioning HFNC use in infants and young children with bronchiolitis. Early observational studies suggested reductions in intubation rates and improved clinical parameters with HFNC; however, more recent randomized controlled trials show no consistent benefit in length of stay, duration of oxygen therapy, pediatric intensive care unit (PICU) transfer rates, or need for mechanical ventilation when compared with conventional low-flow oxygen. HFNC may reduce treatment failure among children who do not respond to low-flow therapy, but its expanding use has been associated with higher healthcare costs, increased PICU admissions, and potential complications such as aerophagia, delayed enteral feeding, and air leak syndromes. Evidence remains limited regarding HFNC use in non-hypoxic children with respiratory distress, and current guidelines do not support "oxygen for comfort." A stepwise, evidence-guided approach to respiratory support, grounded in objective bronchiolitis scoring systems, may help prevent overuse and optimize outcomes. Further research is needed to clarify indications for HFNC, define standardized initiation and escalation criteria, and evaluate its role in non-hypoxic bronchiolitis.