A 76-year old client is admitted for elective knee surgery. Physical examination reveals shallow respirations but no signs of respiratory distress. Which of the following is a normal physiologic change related to aging?
A. Increased elastic recoil of the lungs.
B. Increased number of functional capillaries in the alveoli.
C. Decreased residual volume.
D. Decreased vital capacity.
Correct Answer: D. Decreased vital capacity.
Reduction in VC is a normal physiologic change in the older adult. Other normal physiologic changes include decreased elastic recoil of the lungs, fewer functional capillaries in the alveoli, and an increase is residual volume. Lung volumes depend on body size, especially height. Total lung capacity (TLC) corrected for age remains unchanged throughout life. Functional residual capacity and residual volume increase with age, resulting in a lower vital capacity.
Option A: There is marked variation in the effect of aging on lung function. Aging is associated with reduction in chest wall compliance and increased air trapping. The decline in FEV1 with age likely has a nonlinear phase with acceleration in rate of decline after age 70 years.
Option B: Additionally, decreased strength and function of respiratory muscles is observable. All of these changes drop an aging patient’s threshold in compensating for an acute illness or respiratory failure. Reduction in supporting tissue results in premature closure of small airways during normal breathing and can potentially cause air trapping and hyperinflation, hence “senile emphysema”.
Option C: Subjects with lower chest wall compliance had higher residual volume (RV), suggesting an impediment to complete emptying of the lungs from a stiff chest wall. Age-related changes in the respiratory system primarily center upon the loss of elasticity and decrease in chest wall compliance leading to increased work of breathing, as well as increased residual volume and functional residual capacity.
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