Effect of growth and aging on the static mechanical lung properties.

Quasi-static expiratory pressure-volume curves were obtained in 119 healthy subjects 7 to 64 years old. Lung recoil pressures were measured at six fixed percentages of TLC between 100 percent and 50 percent. In children and adolescents lung recoil pressures increased with growth till about the age of fifteen and there were no differences between sexes. In adults less than 40 years old there was also no sex difference in lung recoil pressures, whereas in subjects more than 40 years old, females had lower recoil pressures than males at every level of TLC. Both in males and females, aging is associated with a marked decrease of lung recoil pressures. Smoking had no detectable effect on lung recoil in males. During growth the evolution of static compliance was closely related to height, whereas in adults this relationship was less evident particularly in males. There was no sex differences in specific compliance which tended to increase slightly with aging.