Airway nitric oxide in infants with acute wheezy bronchitis

Concentrations of nitric oxide (NO) in exhaled air are increased in childre n and adults with asthma, and NO measurements are used as a non-invasive ma rker to monitor airway inflammation in these patients. To define the role o f NO in infants with acute wheezy bronchitis, we measured nasal and end-tid al NO concentrations in 17 infants with acute virus-associated wheezy bronc hitis, in 22 term infants without respiratory disease, and in nine prematur e infants. Nasal NO measurements were performed with an olive placed in the infant's nose; end-tidal NO concentrations were assessed during tidal brea thing through a snugly fitting face mask. Both end-tidal NO concentrations and nasal NO concentrations were reduced in infants with acute wheezy bronc hitis. There were no differences in NO concentrations between term infants and premature infants. Measurements by both techniques were highly reproduc ible, as assessed by repeated measurements three times daily on three conse cutive days in eight premature infants. Reduced airway NO concentrations in infants with virus-associated acute wheezy bronchitis are in contrast to f indings in adults where both upper and lower airway NO levels are increased in patients with asthma. Whether this reflects a different inflammatory re action to upper airway infections in acutely wheezy infants or pathophysiol ogic differences in airway response remains to be determined.