Name a distinguishing feature of chronic obstructive pulmonary disease (COPD).

Chronic obstructive pulmonary disease (COPD) is characterized primarily by progressive airflow limitation, which distinguishes it from other respiratory conditions. This progressive limitation is due to inflammatory processes that lead to structural changes in the lungs and airways, such as airway obstruction and reduced airflow, making it increasingly difficult for patients to breathe over time.

Unlike conditions that present with sudden or acute respiratory distress, COPD manifests as a gradual decline in lung function. Patients with COPD often experience chronic symptoms such as cough, sputum production, and dyspnea that worsen over years rather than through sudden episodes.

While frequent respiratory infections can occur in individuals with COPD due to compromised lung function, this is not a defining feature of the disease itself. Additionally, permanent improvement in lung function does not occur in COPD as the condition is generally progressive and leads to irreversible changes in lung structure and function. Therefore, the key factor that accurately describes COPD and its pathophysiology is the progressive airflow limitation.