Exhaled Nitric Oxide in Respiratory Syncytial Virus (RSV) Bronchiolitis: a Pilot Study

The fraction of exhaled nitric oxide (feNO) in expired air is a reliable measure of airway inflammation. Some research experiments have demonstrated stimulation of nitric oxide production in respiratory epithelial cells infected with RSV. The principal aims are to determine if the fraction of exhaled nitric oxide (feNO) is elevated in hospitalized pediatric patients with viral lower respiratory illness and to determine if there is a difference in feNO level between RSV and non-RSV infection. NO may play a role in the association between RSV, airway reactivity, and airway inflammation. This is a prospective, pilot study that will noninvasively measure feNO in children 0-4 years of age admitted to Winthrop University Hospital, as well as controls (children in the same age range without respiratory conditions and who are well enough to perform the test). Hospitalized children will be tested for RSV (enzyme immunoassay (EIA) \& DFA) and via direct fluorescent antigen technique (DFA) for influenza A \& B, parainfluenza, human metapneumovirus and adenovirus. Method of feNO measurement will utilize the offline options for preschool children \& infants appropriate for age as described in the 2005 Joint Statement of the American Thoracic Society \& the European Respiratory Society when discussing tidal breathing techniques with uncontrolled flow rate Offline exhaled air can be collected via a mouthpiece or a face mask connected to a non-re-breathing valve that allows inspiration of NO-free air from an NO-inert reservoir to avoid contamination by ambient NO. Exhaled breath samples are collected into an NO-inert bag fitted with the expiratory port once a stable breathing pattern is present. The results of all 3 groups will be compared: control, RSV positive and RSV negative samples.