Emphysem

Emphysem, sometimes referred to as emphysema, is a lung condition defined by permanent enlargement of airspaces distal to the terminal bronchioles and destruction of the walls separating adjacent airspaces, resulting in loss of elastic recoil and airflow limitation. It is a major component of chronic obstructive pulmonary disease (COPD) and can occur with or without chronic bronchitis.

Causes and risk factors include long-term exposure to lung irritants such as cigarette smoke, occupational dusts and chemicals, and, in some individuals, inherited deficiency of alpha-1 antitrypsin. The disease mechanism involves an imbalance of proteolytic enzymes and their inhibitors in the lung, leading to destruction of alveolar walls, decreased surface area for gas exchange, and air trapping. Emphysema is categorized by patterns of involvement within the acinar structures, including centrilobular (more common in smokers), panacinar (associated with alpha-1 antitrypsin deficiency), and paraseptal emphysema.

Clinical features typically include progressive dyspnea on exertion, reduced exercise tolerance, and a chronic cough. Sputum production varies and may be minimal. On examination, patients may show signs of hyperinflation, diminished breath sounds, and, in advanced cases, a barrel-shaped chest. Diagnosis relies on spirometry showing a reduced FEV1/FVC ratio with an obstructive pattern, often accompanied by reduced diffusing capacity (DLCO). Imaging, such as chest radiography or CT, demonstrates hyperinflation and characteristic parenchymal destruction.

Management focuses on symptom relief, prevention of disease progression, and complication reduction. Smoking cessation is the most effective intervention. Pharmacologic therapy includes bronchodilators and, when appropriate, inhaled corticosteroids. Pulmonary rehabilitation, oxygen therapy for hypoxemia, and vaccinations are recommended. In selected cases, surgical options such as lung volume reduction surgery or transplantation may be considered. The prognosis varies with disease extent, comorbidities, and response to treatment.