Acute Bronchiolitis: The Less, the Better?

Abstract

Background: Acute bronchiolitis is a viral infection of the lower respiratory tract affect- ing infants aged under 12 months, variably presenting with respiratory distress, diffuse crackles and inflammatory wheezing. The main causative agent is Respiratory Syncytial Virus (RSV). The diagnosis is clinical and treatment mainly supportive. Despite the availability of more than 30 in- ternational guidelines, consistent management recommendations are lacking and considerable vari- ability in patients’ care persists among different providers. Objective: To review and describe current knowledge about epidemiology, physiopathology, clin- ic, diagnosis and management of acute bronchiolitis, with particular emphasis on updated evidence and future perspectives in terms of treatment and prevention. Methods and Results: We searched Cochrane for systematic reviews and PubMed for scientific ar- ticles published in the last 10 years, using a combination of the following search terms: “bronchi- olitis”, “respiratory syncytial virus”, “epidemiology”, “risk factors”, “severity”, “diagnosis”, “clin- ic”, “diagnostic imaging”, “management”, “asthma”, “wheezing”, “bronchodilator”, “steroids”, “hypertonic saline”, “oxygen”, “blood gas analysis”, “HHHFNC”, “rehydration”, “enteral feed- ing”, “parenteral hydration”, “prevention”, “vaccine” and “COVID-19 or SARS-CoV2”. We ac- cordingly performed a deep and extensive selection of the most updated and considerable litera- ture on the matter, summarizing the most significant evidence concerning all aspects of acute bron- chiolitis (epidemiology, clinic, diagnosis, management and prevention). Furthermore, we ex- amined references and available guidelines from UK, USA, Canada, Italy and Spain. Results are extensively discussed below. Conclusion: Although acute bronchiolitis has been a widely known disease for decades, its thera- peutic approach remained unchanged and essentially limited to respiratory and metabolic support. Despite the abundance of studies, there is no significant evidence concerning therapeutic alterna- tives (e.g. steroids, inhaled hypertonic solution), which are therefore not recommended. Accord- ing to most recent data, “acute bronchiolitis” definition encompasses a plethora of different clini- cal entities related to each subject’s genetic and immune predisposition. Therefore, future research should focus on the precise characterization of such subcategories in order to individualize thera- peutic management and ensure the most appropriate evidence-based care.