PULMONARY: Airway closure in normal subjects and patients with cystic fibrosis

Abstract

Lung units close as lung volume is reduced and the volume at which closure occurs (CV) can be detected as a discontinuity of the alveolar plateau in the single breath nitrogen washout (Anthonisen, N. R.: Resp. Physiol. 8, 58–65, 1969–70). We have used this technique to define the closing volumes of 23 normal children, ranging from 8–18 years and 136–179 cm height, and those of 16 patients with cystic fibrosis, 7–27 years and 125–176 cm, with the following results; All differences are highly significant (P > 0.01).Six of the 16 patients with cyctic fibrosis had a closing volume greater than the functional residual capacity, indicating gas trapping during normal tidal breathing. Closing at high lung volume is a major facttor in producing the gas exchange failure in these cases. for this reason this method appears to be a sensitive indicator of gas exchange abnormality in certain pulmonary diseases in childhood.