Which type of lung disease is defined by a decreased ability to expand the lungs?

Restrictive lung disease is characterized by a decreased ability of the lungs to expand fully, leading to a reduced total lung capacity. This condition can result from various factors, including stiffness of the lung tissue (as seen in interstitial lung diseases), chest wall abnormalities, or conditions that impair the mechanics of breathing.

In restrictive lung disease, patients typically experience difficulty in taking deep breaths, which limits their overall ventilation capacity. The key feature is that the lungs are unable to expand adequately during inspiration, contrasting with obstructive lung diseases where airflow is primarily limited during expiration due to airway obstruction or narrowing, but the lung volumes may still be normal or increased.

Understanding this difference is crucial because it helps in the diagnosis and management of patients with respiratory disorders, as the treatment approaches can vary significantly between restrictive and obstructive conditions. Infectious lung disease pertains to ailments caused by pathogens affecting lung function through different mechanisms, while vascular lung disease involves issues related to the pulmonary vasculature and blood flow, not the ability of the lungs to expand.