What commonly happens to exhalation in obstructive lung disease?

• A. It is enhanced
• B. It remains normal
• C. It is impaired
• D. It is lengthened

Answer: (C)

In obstructive lung disease, the primary pathophysiological change affects the ability to exhale air from the lungs. Conditions such as asthma, chronic obstructive pulmonary disease (COPD), and bronchiectasis involve a narrowing of the airways, making it more difficult for air to flow out during exhalation. This impairment occurs because the inflamed or constricted airways create resistance to airflow, which leads to an incomplete expulsion of air. This not only reduces the amount of air that can be expelled but can also trap air in the lungs, leading to hyperinflation.

This diminished expiratory flow can be evidenced by a decreased FEV1/FVC (forced expiratory volume in one second / forced vital capacity) ratio on pulmonary function tests, indicating that exhalation is not only impaired but also occurs over a longer duration due to the resistance encountered during the expiratory phase.

Understanding this concept is essential for managing patients with obstructive lung diseases, as therapies often aim to reduce airway resistance and improve exhalation.