What is the effect of increased residual volume (RV) in patients with emphysema?

• A. Decreased total lung capacity
• B. Increased risk of lung infections
• C. Increased work of breathing
• D. Decreased lung compliance

Answer: (C)

In emphysema, the destruction of the alveolar walls leads to the loss of elastic recoil in the lungs, which results in air trapping and an increase in residual volume (RV). As the RV increases, the lungs are unable to empty fully during expiration, leading to an increase in the amount of air left in the lungs after a full exhalation.

This elevated residual volume contributes to the increased work of breathing because the respiratory muscles must work harder to accommodate both the trapped air and the air that needs to be inhaled during subsequent breaths. The respiratory system becomes less efficient, and patients often experience difficulty in breathing, which can manifest as shortness of breath, especially during physical exertion. The increased work of breathing may lead to respiratory muscle fatigue over time.

Understanding this relationship helps to clarify why increased residual volume is directly linked to the increased effort required for breathing in individuals with emphysema. Other options such as decreased total lung capacity or decreased lung compliance do not accurately describe the physiological changes associated with emphysema in relation to increased residual volume.