MCQ – 89265

Correct Answer � A Explanation

Answer A. Increased lung compliance

The patient lacks any history of respiratory disease and has a normal physical examination. Therefore, her change in respiratory function is likely a consequence of normal aging.

Increased lung compliance

• Increased lung compliance is commonly found in individuals of advanced age due to loss of elastic fibers. 

• Chest wall compliance typically decreases because of increased chest wall stiffness. 

• Stiffening of the chest wall and loss of elastic recoil impair lung emptying during expiration, which increases residual volume. When compared to a healthy young adult, individuals of advanced age have increased alveolar dead space and increased V/Q mismatch due to age-related loss of lung surface area. 

• Moreover, while FEV1 and vital capacity classically decrease with age, total lung capacity usually remains unchanged.

• Other age-related changes include decreased respiratory muscle strength (which can hinder effective coughing and increase the risk of aspiration and infection) and impaired ventilatory response to hypercapnia and hypoxia.

Increased vital capacity

• Vital capacity (VC = tidal volume + IRV + ERV) commonly decreases (not increases) with advanced age. This is primarily due to loss of elastic recoil and stiffening of the chest wall.

Decreased residual volume

• Residual volume can be decreased in restrictive lung disease. With advanced age, residual volume classically increases (not decreases) due to loss of elastic recoil and increased chest wall stiffening.

Decreased total lung capacity

• Decreased total lung capacity (TLC = vital capacity + residual volume) is classically seen in patients with restrictive lung disease. While normal aging is associated with an overall decrease in lung function, TLC will remain constant in the absence of respiratory disease.