Overview of bronchiolitis

Respiratory syncytial virus RSV, a nonsegmented, single stranded ribonucleic acid virus, infects one-half of all infants within the first year of life. Respiratory syncytial virus possesses pathogenetic qualities that may be attributed to the interplay of viral and host-specific factors including virus strains of different virulence, size of the inoculum, family history of asthma or airway hyper-reactivity and immunologic anomalies of the host. Inflammatory cell recruitment and activation occur in response to RSV infection of epithelial cells. Epithelial cells initiate the inflammatory response to RSV by elaborating a wide variety of cytokines and chemokines that trigger further inflammatory responses. Treatment of RSV in infants with bronchiolitis is complicated due to the multifactorial nature of this infection. Treatment of RSV bronchiolitis rests primarily on supportive care with oxygen and fluid management. Other therapies commonly used include bronchodilators, corticosteroids and ribavirin, where considered appropriate. Although oxygen administration and judicious fluid replacement are the only interventions proved to be of reliable benefit to infants with bronchiolitis, newer studies support a role for adjunctive therapies aimed at relieving airway obstruction, especially when administered very early in the course of the illness or given to infants with more severe disease.