Growth of airways and air spaces in teenagers is related to sex but not to symptoms.

To determine growth patterns of the lung and airways in adolescents, we analyzed maximal expiratory flow-volume curves, closing capacity, and residual volume. They were obtained every 6 mo for up to 7 yr in 430 boys and 125 girls (11-19 yr), of whom 143 boys and 36 girls were classified as symptomatic; symptoms were most often minor and limited to childhood. Development of flows vs. volumes was used to investigate growth of the airways relative to lung size. A model of isotropic growth of the airways and air spaces (J. Appl. Physiol. 65: 822-828, 1988) was modified for increasing elastic recoil pressure with growth. Growth of airways relative to volume occurred faster in teenage boys than in teenage girls and was compatible with isotropic growth in 92% of asymptomatic boys and in 44% of asymptomatic girls: dysanaptic growth in teenage girls seems to be a normal phenomenon and not a unique characteristic of symptomatic subjects. Subjects with respiratory symptoms in childhood and/or adolescence have lower flows for a given lung size and airway closure at a greater lung volume when they enter adulthood. However, no difference in patterns of lung growth was observed in association with the presence of respiratory symptoms.