The most common symptom arising from a pleural inflammatory response is pleuritic pain, which is mediated by the parietal pleura (the visceral pleura contains no nociceptors or nociceptive nerve fibers). The pain is usually felt in the region of the pathological abnormality, and it is often linked to the respiratory cycle. Such localized pleuritic pain improves or disappears as soon as a pleural effusion arises. Some patients describe a diffuse, painful sensation of pressure in the chest—particularly when the pathological process directly involves the parietal pleura, e.g., in the case of a pleural empyema, a primary malignant tumor, or pleural carcinomatosis. Pleural effusions in these situations are usually of the exudative type.The most common symptom of pleural effusion is dyspnea. The severity of dyspnea is only loosely correlated with the size of the effusion (3). Large pleural effusions take up space in the chest that is normally filled by pulmonary parenchyma and are thus associated with a diminution of all lung volumes. Nor do the lung volumes immediately change when a pleural effusion (even a large one) is drained. The rapid clinical improvement of dyspnea after a pleural effusion is drained probably reflects the transition to a more favorable length-tension curve of the respiratory muscles, particularly the diaphragm (3).Some patients complain of a dry cough, which can be explained as a manifestation of pleural inflammation or lung compression due to a large effusion. Pleural effusions can also markedly impair the quality of sleep