RECOMMENDATIONS OF THE SPANISH SOCIETY OF PULMONOLOGY AND THORACIC SURGERY (SEPAR) Diagnosis and Treatment of Pleural Effusion

Pleural fluid originates in the pleural capillaries (mainly those of the parietal pleura), lymphatics, intrathoracic blood vessels, the interstitial pulmonary space, and the peritoneal cavity. It is reabsorbed mainly through the lymphatics of the parietal pleura. The mechanisms that cause pleural effusion all result in an increase in the production or a decrease in the removal of pleural fluid and may be related to changes in hydrostatic capillary, intravascular or extravascular colloid osmotic, and negative intrathoracic pressures (Table 1). The prevalence of pleural effusion is slightly in excess of 400/100 000 population. Congestive heart failure is the most common cause of pleural effusions overall. However, the predominant etiologies among the exudates are pneumonia, malignancy, and pulmonary embolism. Table 2 shows the most common causes of pleural effusion.