Sex and age differences in pulmonary mechanics in normal nonsmoking subjects

Abstract

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.

Lung elastic recoil in normal young adult Chinese compared with Caucasians

“…The PLmax of our subjects was lower than the PLmax of 34.5±12.7 (20.0-69.0) cmH 2 O obtained in 21 healthy Caucasian subjects (15 males and 6 females) of comparable age (29±5 yrs) [13]. However, our patients had lower TLC (5.2±1.2 l) compared with the same Caucasian subjects (6.5±1.1 l).…”

“…The B/A in our subjects was significantly higher in males compared with females, which implies that males have a higher lung recoil at the same lung volume. This is not unlike male Caucasian subjects, who tend to have higher lung recoil then their female counterparts of comparable age [12][13][14]. However, the difference in PLmax was not statistically significant between our male and female subjects.…”

“…However, CLst/TLC was related to the position index B/A, whereas K was not. Loss of lung recoil is recognized as part of the normal ageing process [12][13][14]. The shape constant, K, has been shown to increase linearly with age [4][5][6], but, probably due to the younger age and narrow age range of our subjects, we were unable to demonstrate this relationship.…”

Ageing and changes in lung mechanics

“…The increase in FRC was due to an increase in relaxation volume of the respiratory system, which arose from changes in the static recoil pressure of both the chest wall and the lungs. Static recoil pressure of the lungs (PL) fell at all lung volumes with increasing age [5,6]. The fall in PL contributed to the increase in RV, but this was usually overshadowed by an increased tendency to airway closure at small volume [7], itself reflecting a reduced airway transmural pressure.…”

“…Perhaps an unchanging sRaw is itself unexpected, because BUTLER et al [11] also proposed that reductions in Raw with lung inflation were driven by the accompanying change in PL, which they regarded as a surrogate for the distending pressure of the intrathoracic airways. The most obvious explanation for retaining a normal or even reduced Rrs in old age is that changes in airway elasticity occurred in parallel with those in alveolar elasticity, so that aged airways have a bigger circumference at a standard distending pressure than the airways of younger adults [6]. VC and maximum flows at different lung volumes is of wider practical importance.…”