Age-Related Changes in Respiratory Function
The correct answer is (d) increased residual volume (RV).
Understanding Residual Volume and Age-Related Changes
Residual volume (RV) is the amount of air that remains in the lungs after a maximal exhalation. It increases with age as a normal physiological change in respiratory function 1.
Key age-related changes in lung volumes:
- RV increases in an approximately linear fashion with aging in healthy adults 1
- This increase in RV occurs throughout the lung, not just in specific regions 2
- TLC (total lung capacity) generally does not change significantly with aging in healthy adults 1
- The RV/TLC ratio increases with age, reflecting the increased proportion of air that cannot be exhaled 3
Mechanisms Behind Increased Residual Volume with Age
Several physiological changes contribute to the age-related increase in residual volume:
- Airways throughout the lung close at higher volumes as age increases 2
- Loss of elastic recoil in the lung tissue occurs with aging 4
- Altered emptying sequences within lung regions due to retarded emptying of highly compliant lung regions 2
- Decreased respiratory muscle strength with aging, making complete exhalation more difficult 1
Clinical Significance of Increased Residual Volume
The increase in residual volume with age has several clinical implications:
- It can be mistaken for early signs of obstructive lung disease 5
- An isolated elevation in RV (without other pulmonary function test abnormalities) is associated with airway-centered diseases 5
- Increased RV is often observed in airway obstruction and may be an important gauge of response to bronchodilators 6
- In smokers, there is a dose-response effect between RV percent predicted, RV/TLC percent, and pack-years of smoking 3
Other Respiratory Changes with Age (Incorrect Options)
- Total lung capacity (TLC) typically remains stable with aging, not decreased or increased 1
- Functional residual capacity (FRC) changes with age are inconclusive, but it does not consistently decrease 1
- Vital capacity (VC) tends to decrease with age, not increase 1
The European Respiratory Society guidelines confirm that while TLC remains relatively stable with aging, RV increases linearly with age, making option (d) the correct answer 1.