A community study of exhaled nitric oxide in healthy children

Exhaled nitric oxide (eNO) is elevated in patients with inflammatory pulmon ary diseases and it has attracted increasing interest as a simple, noninvas ive marker of airway inflammation. Little is known, however, about factors that might affect eNO in healthy subjects. We measured eNO in 157 healthy 7 - to 13-yr-old children (mean 9.7 yr, 77 girls), with no history of respira tory tract disease, using a recently validated, single-breath technique. Me asurements of eNO were obtained at driving (mouth) pressures of 10, 15, and 20 cm H2O and 3 eNO plateaux were achieved for each child at each pressure . Exhaled NO decreased with increasing pressure (increasing expiratory flow ) (p < 0.001) and increased with age (p < 0.001). Concentrations were great er in children with a positive skin prick test (p < 0.0001). Geometric mean eNO levels were 7.2 ppb in children with no positive skin prick tests (n = 116), 10.9 ppb in children with one positive reaction (n = 24), and 20.1 p pb in children with two or more skin reactions (n = 17). Age and immunologi cal reactions to common allergens are associated with increased eNO in chil dren and should be controlled for in studies of eNO. The mechanisms respons ible for these associations require further study.