Pulmonary function following mild respiratory tract infections (“common cold”) in teenagers

Ventilatory function—forced vital capacity (VC)—forced expiratory volume (in 1‐sec forced expiratory flows) static lung volumes, closing volume, and phase III slope (singlebreath N 2 test) were compared in 94 children with and 436 children without a history of recent mild acute respiratory infection. Their age ranged from 10 to 16 years; subjects with symptoms on the day of the study were excluded. We found no difference in lung function between the two groups, with the exception of a slight (inconsistently significant) increase in closing volume (CV) and the CV/VC ratio. Although the influence of a persistent increase in interstitial lung pressure leading to early small airways closure cannot be ruled out, this isolated functional abnormality probably represents a spurious positive result, arising by chance when a large number of statistical tests are done.