Sex and age differences in pulmonary mechanics in normal nonsmoking subjects

Maximun flow-volume, static pressure-volume, and maximum flow static recoil curves of three groups of nonsmoking, normal subjects (young men, young women, elderly women) were used to assess age and sex differences in pulmonary mechanics. No significant sex differences in maximum flow were seen but the young men showed higher lung recoil pressures at full inflation. When the influence of the inspiratory muscles and chest wall was excluded by exponential extrapolation of the pressure-volume curves to a maximum volume the bulk elastic properties of the lungs of young men and women appeared identical. Loss of maximum expiratory flow at low lung volumes and of lung recoil pressure occurred with age in nonsmoking women in whom emphysema should be minimal and therefore indicate true physiological effects of aging. The changes in pulmonary mechanics with age are consistent with an increase in unstressed dimensions and loss of elastic recoil of both alveoli and airways.