Which test is typically reduced in patients with restrictive lung disease?

In patients with restrictive lung disease, the forced vital capacity (FVC) is typically reduced. Restrictive lung diseases lead to a decrease in lung volumes, which is characterized by a diminished total lung capacity. In these conditions, the ability of the lungs to expand is impaired, which directly affects the amount of air that can be forcibly exhaled after a maximal inhalation, thereby reducing the FVC.

While the forced expiratory volume in 1 second (FEV1) can also be affected in some cases, it is not as consistently reduced in restrictive lung disease as FVC. In fact, the FEV1/FVC ratio may remain normal or even increase because both values decrease due to the restrictive process. Similarly, peak expiratory flow rate is more commonly associated with obstructive lung disease since it measures the maximum speed of expiration rather than volume. Lastly, lung diffusion capacity is a separate measure that assesses how well gases transfer from the lungs to the blood, which may not be consistently reduced across all restrictive lung diseases.

In summary, decreased forced vital capacity is a hallmark of restrictive pulmonary conditions, making it the correct choice in this clinical context.