Certified Respiratory Therapist Exam 2025 – 400 Free Practice Questions to Pass the Exam

Restrictive pulmonary diseases primarily affect lung volumes, specifically the total capacity of the lungs to hold air. In these conditions, the lungs become stiff, and the expansion during inhalation is limited due to various factors such as interstitial lung disease, pulmonary fibrosis, or chest wall deformities. As a result, the ability to take in sufficient air is compromised, leading to a reduction in lung volumes.

While diffusion capacity can also be affected due to the thickening of alveolar membranes or other changes in lung structure, the defining characteristic of restrictive lung disease is the reduction in overall lung volume. Vital capacity, which is the maximum amount of air a person can exhale after a maximum inhalation, would also be diminished in restrictive diseases; however, this metric is more specific than the broader categorization of lung volumes. Airway resistance typically pertains to obstructive conditions rather than restrictive ones. Thus, lung volumes accurately represent the primary impairment in restrictive pulmonary diseases.