Pleural Effusion

About Pleural Effusion

Pleural effusion is the abnormal accumulation of fluid in the pleural space between the visceral and parietal pleura surrounding the lungs. It can be classified as transudative (due to altered hydrostatic or oncotic pressures) or exudative (due to increased capillary permeability or impaired lymphatic drainage). Common causes include heart failure, pneumonia, malignancy, and pulmonary embolism.

Pathophysiology

Normal pleural fluid production occurs through filtration from parietal pleural capillaries, with reabsorption via visceral pleural capillaries and lymphatics. Disruption of this balance leads to fluid accumulation through increased hydrostatic pressure (heart failure), decreased oncotic pressure (hypoalbuminemia), increased capillary permeability (inflammation), or impaired lymphatic drainage (malignancy). The accumulated fluid compresses lung tissue, reducing functional residual capacity and causing ventilation-perfusion mismatch.

Clinical Reasoning

Clinical presentation typically includes dyspnea, pleuritic chest pain, and decreased exercise tolerance, with physical examination revealing decreased breath sounds, dullness to percussion, and reduced tactile fremitus on the affected side. Chest imaging confirms the diagnosis, while pleural fluid analysis through thoracentesis helps differentiate transudative from exudative causes using Light's criteria. Management focuses on treating the underlying cause and may require therapeutic thoracentesis or chest tube drainage for symptomatic relief.