Bronchiolitis: Focus on hypertonic saline

Bronchiolitis is arguably the most common significant medical illness of childhood. At least 1 in 7 normal infants will develop symptomatic bronchiolitis in his or her first year of life.¹ Hospitalization of infants for bronchiolitis is responsible for an annual expenditure of more than a half billion dollars.² Despite the extraordinary prevalence of this condition, the disease confers very little mortality. There are about 100 deaths resulting from bronchiolitis each year, and the bulk of these deaths are in children with other underlying conditions such as chronic lung disease, congenital heart disease, or other chronic diseases.^3,4

Pathophysiology

Respiratory syncytial virus (RSV) infection remains the most common cause of bronchiolitis, but recently, multiple other viruses, including adenovirus, parainfluenza virus, influenza, coronavirus, rhinovirus, and human metapneumovirus, have been recognized as etiologic agents of the condition.^5-7 The growing list of causative pathogens for bronchiolitis is not so much a reflection of rapid viral evolution as it is a result of our better understanding of the viral pool. Human metapneumovirus first gained recognition as a major pathogen in bronchiolitis in 2004.⁶ Previously considered the least pathogenic of viruses, rhinovirus has been implicated as an organism in particularly severe disease.⁷ There doubtlessly will be more viruses discovered in the near future.

Other studies have reported higher rates of pneumonia or gastrointestinal symptoms, increased hospital stay, and/or increased need for oxygen associated with coinfection.^10-13

All the studies, however, have some design limitations, so whether increased severity or other detrimental outcomes result from coinfection still requires further confirmation. In both inpatient and community settings, contact and droplet precautions should be the mainstay of prevention of viral transmission.