Which lung function test result is likely to be affected in patients with COPD?

In patients with Chronic Obstructive Pulmonary Disease (COPD), one of the hallmark features is airflow limitation, which is reflected in the lung function test results. Specifically, decreased flows, particularly during expiration, are commonly observed.

In COPD, the airways become narrowed or blocked due to inflammation, mucus production, and structural changes, leading to a reduction in the maximum flow rates that can be achieved during forceful expiration. This is typically measured by parameters such as Forced Expiratory Volume in 1 second (FEV1) and Forced Vital Capacity (FVC). In these individuals, the FEV1 is especially compromised, resulting in a lower ratio of FEV1 to FVC, which is a key indicator of obstructive lung disease.

Since normal tidal volume refers to the amount of air breathed in and out during normal breathing, it generally remains unchanged in COPD patients until the disease progresses significantly. Increased vital capacity is not characteristic of COPD, as patients often have a reduced vital capacity due to the restrictive components of lung hyperinflation. Similarly, increased gas diffusion does not typically occur in COPD; rather, diffusing capacity may actually be reduced in advanced stages due to emphysema.

Thus, decreased flows is the result in lung