New paradigms in acute viral bronchiolitis: Is it time to change our approach?

Viral bronchiolitis is the most common pediatric acute respiratory infection leading to hospitalization, and it causes a significant healthcare burden worldwide. Current guidelines recommend supportive management after many clinical trials on specific therapies failed to demonstrate benefits. However, several studies in the past decade have revealed that bronchiolitis may not be a homogeneous disease, but instead may constitute an umbrella comprised of different "endotypes" and "phenotypes" based on patient characteristics, etiology, pathophysiological mechanisms, and clinical presentation. In this extensive review, we summarize the current evidence that several different types of bronchiolitis ("bronchiolitides") coexist, with different short- and long-term consequences on respiratory health and the risk of asthma development. Disease pathobiology, immune response, and clinical characteristics may differ between the two most prevalent viral agents, respiratory syncytial virus and rhinovirus. Recent randomized trials have shown that some subgroups of children may benefit from the use of systemic corticosteroids and/or bronchodilators. These findings also suggest that some children may benefit from individualized therapeutical approaches for viral bronchiolitis rather than following broad recommendations for treating all patients uniformly using only supportive management.