Pleural effusion
| Pleural effusion | |
|---|---|
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|
| Diagram of fluid buildup in the pleura | |
| Classification and external resources | |
| Specialty | Pulmonology |
| ICD-10 | J90-J91 |
| ICD-9-CM | 511.9 |
| MedlinePlus | 000086 |
| MeSH | D010996 |
A pleural effusion is excess fluid that accumulates in the pleural cavity, the fluid-filled space that surrounds the lungs. This excess can impair breathing by limiting the expansion of the lungs. Various kinds of pleural effusion, depending on the nature of the fluid and what caused its entry into the pleural space, are hydrothorax (serous fluid), hemothorax (blood), urinothorax (urine), chylothorax (chyle), or pyothorax (pus). A pneumothorax is the accumulation of air in the pleural space, and is commonly called a "collapsed lung."
Various methods can be used to classify pleural fluid.
By the origin of the fluid:
By pathophysiology:
By the underlying cause (see next section).
The most common causes of transudative pleural effusions in the United States are heart failure and cirrhosis. Nephrotic syndrome, leading to the loss of large amounts of albumin in urine and resultant low albumin levels in the blood and reduced colloid osmotic pressure, is another less common cause of pleural effusion. Pulmonary emboli were once thought to cause transudative effusions, but have been recently shown to be exudative. The mechanism for the transudative pleural effusion is probably related to increased permeability of the capillaries in the lung, which results from the release of cytokines or inflammatory mediators (e.g. vascular endothelial growth factor) from the platelet-rich blood clots. The excessive interstitial lung fluid traverses the visceral pleura and accumulates in the pleural space.
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