Chasing the Latest Rabbit: High Flow Nasal Cannula and Bronchiolitis.

The search for effective evidence-based management strategies for children hospitalized with acute viral bronchiolitis is filled with dark rabbit holes of potential benefit that, for the most part, have led right back to the beginning. Such has been the case for antiviral agents, bronchodilators, systemic and inhaled corticosteroids, and, most recently, nebulized hypertonic saline. A new tool in the ever-changing toolbox of bronchiolitis that has gathered recent enthusiasm is high-flow nasal cannula (HFNC). HFNC is an oxygen delivery strategy that uses heated and humidified air that allows for higher flows than typical oxygen delivery methods such as simple nasal cannula or a face mask. This enthusiasm is mostly based on retrospective data showing decreased intubation rates in the emergency department and intensive care setting, as well as some limited data that argue for its safety in the general inpatient wards. The enthusiasm regarding HFNC is tempered by the fact that the studies arguing for decreased intubation rates were retrospective and observational in nature and used historical cohorts to compare outcomes after HFNC implementation. Historical cohorts may have biased these initial studies by failing to take into account secular trends in practice.