Final answer:
Interstitial lung disease is characterized by scarring and inflammation leading to stiff and less compliant lungs, resulting in restrictive lung disease and reduced forced vital capacity.
Step-by-step explanation:
Interstitial lung disease (ILD) refers to a group of disorders characterized by scarring (fibrosis) and inflammation of the lung tissue. Notably, in diseases such as pulmonary fibrosis and respiratory distress syndrome, the lungs become stiff and less compliant, meaning it's harder for them to expand and fill with air. This decreased compliance leads to increased intrapleural pressure, causing the airways to collapse upon exhalation and trapping air in the lungs. As a result, the forced vital capacity (FVC), the amount of air exhaled after a deep breath, is significantly reduced. Patients with ILD may experience severe, progressive shortness of breath, persistent dry cough, and fatigue. The diagnostic process can include pulmonary function tests, high-resolution computed tomography (HRCT), and occasionally bronchoalveolar lavage (BAL). In contrast to conditions such as COPD and emphysema, where the problem lies in poor airflow and damaged alveoli, ILD primarily affects the lung tissue around the alveoli, leading to restrictive lung disease.