EXHALED NITRIC-OXIDE IN PEDIATRIC ASTHMA AND CYSTIC-FIBROSIS

Nitric oxide (NO) is present in exhaled air of humans. This NO is most ly produced in the upper airways, whereas basal NO excretion in the lo wer airways is low, Children with Kartagener's syndrome have an almost total lack of NO in nasally derived air, whereas adult asthmatics hav e increased NO in orally exhaled air. NO excretion was measured in the nasal cavity and in orally exhaled air in 19 healthy children, in 36 age matched subjects with asthma, and in eight children with cystic fi brosis. NO levels in orally exhaled air were similar in controls and i n children with cystic fibrosis, at 4.8 (SD 1.2) v 5.8 (0.8) parts per billion (ppb), but were increased in asthmatic children who were untr eated or were being treated only with low doses of inhaled steroids (1 3.8 (2.5) ppb). Nasal NO levels were reduced by about 70% in children with cystic fibrosis compared to controls and asthmatics. Measurements of airway NO release in different parts of the airways may be useful in non-invasive diagnosis and monitoring of inflammatory airway diseas es.