Final answer:
The statement is true; in emphysema patients, residual volume increases over time due to the trapping of air in the damaged alveoli.
Step-by-step explanation:
The statement "The PFT of a patient with emphysema shows an increase in residual volume over time." is indeed true. Emphysema is a chronic respiratory condition where the air sacs in the lungs, or alveoli, are damaged, which leads to an increase in the volume of air that remains in the lungs after a full expiration. This air is known as the residual volume. Over time, as the condition progresses, more and more air becomes trapped in the alveoli and cannot be exhaled, hence the residual volume increases. Another related lung volume that contributes to pulmonary function tests (PFTs) is the inspiratory reserve volume, which measures the amount of air that can be further inhaled after a normal breath, not the amount of air remaining in the lung after a maximal exhalation.