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Pleural effusion
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Between the lung and the chest wall lies the pleura, the tissue that covers them, and there is always a little fluid between its layers acting as a lubricant, like the drop of oil you put on a hinge. Pleural effusion is the name for what happens when that small amount grows and too much fluid builds up in that space.
It is important to understand that the fluid is not the enemy: the body makes it on purpose, in small amounts, so the surfaces can glide. The problem is the amount, not the fluid. And that excess fluid builds up through two very different routes. In the first, it leaks into that space, pushed out by high pressure in the blood vessels or by too little protein in the blood; that kind is called transudative, and its most common cause is heart failure. In the second, the fluid escapes because of inflammation, an infection, an injury to the lung, or tumors; that kind is called exudative. Two different routes to the same buildup of fluid.
In brief
A pleural effusion is a buildup of fluid between the layers of tissue that line the lungs and the chest cavity.
The body normally makes a small amount of pleural fluid to lubricate the surface of the pleura; an effusion is an abnormal, excessive buildup of it.
There are two types: transudative effusions come from fluid leaking out because of high pressure in the blood vessels or low protein in the blood, most often from heart failure; exudative ones come from inflammation, infection, lung injury, or tumors.
Sources (1)
- MedlinePlus, U.S. National Library of MedicinePleural effusion (Medical Encyclopedia)
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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