[Physiological aspects of the decline of pulmonary function with age].

After peaking between the age of 20 and 30 years, pulmonary function declines gradually with age. This decline is related to changes in respiratory dynamics (lung mechanics, gas exchange) and also to non-respiratory factors (e.g. changes in the immune system). This age-related fall in pulmonary function is not linear, for example there is no further decline in mean PaO2 in men and women, nor in the FEV1/FVC ratio in men, afterthe age of 70 years. Caution is required when interpreting changes in pulmonary mechanics in the elderly due to greater variability of reference values in this age group.