Pleural effusion
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The pleural cavity is the fluid filled space that surrounds the lungs, and pleural effusion is when there is an excessive amount of this fluid filling up that cavity. It is sometimes called “water on the lungs.” Too much fluid can make it difficult to breathe, because it can press in on the lungs, making expansion impossible.

There are four different kinds of fluids that might accumulate in the pleural cavity. They are:
 Serous fluid, which is usually pale yellow and transparent. This substance is usually benign and assists the body in digestion, excretion, and respiration.
 Chyle is a milky fluid made up of lymph and fatty acids. It is formed in the small intestine during digestion and transported by lymph vessels away from the gastrointestinal tract.
 Pus is a yellow substance produced during an infection or inflammation. It consists of a thin, protein-rich fluid and dead cells, which are part of the body’s immune response.


A small amount of fluid, less than 15 milliliters, in each pleural cavity is considered normal. The body is usually efficient at moving natural fluids through these spaces and removing them by means of lymphatics, different parts of the lymphatic system whose function is to move fluids through the body. Lymphatics have a fluid capacity 20 times greater than the amount the lungs usually require, but in some cases even this capacity can be overwhelmed. When that happens, a pleural effusion forms.

There are two different types of effusions. A transudative pleural effusion is usually caused by abnormal pressure from the lungs themselves, and is most commonly caused by congestive heart failure. It can also be the result of pericarditis, an inflammation of the membrane around the heart. In addition, some people who suffer from liver disease experience pleural effusion as a complication. A second type, exudative effusion, forms as a result of inflammation or infection. This type can be caused by lung disease. One serious example of a lung disease that causes of this type of effusion is lung cancer—40% of the occurrences of this type of effusion result from tumors. Exudative effusions can also be caused by pneumonia, tuberculosis, other lung infections, and from pulmonary embolism—which should be evaluated for, since sometimes pleural effusion is its only symptom. It can also be caused by connective tissue diseases, an injury to the chest, asbestiosis, a lung disease caused by exposure to asbestos, and sarcoidosis, which can affect other tissues in the body as well.

Sometimes a pleural effusion will not display any symptoms at all. But in some cases, the symptoms of pleural effusion can be very uncomfortable. They include
 Decreased movement of the chest on the affected side, meaning that you simply cannot expand your chest as much as you usually would for comfortable breathing;
 Diminished breath sounds, meaning that a doctor would hear shallow breathing;
 Rapid breathing;
 Gastric discomfort;
 Persistent hiccups;
 Decreased vocal vibrations, because the fluid is absorbing the sound waves usually conducted by your breath;
 Egophony, which is a high-pitched or nasal sound to your voice due to the absorption of lower-end sound waves by the fluid in the effusion;
 Chest pain, especially a sharp pain that is worse when you cough or breathe deeply.
pleural effusion
Image: Pleural Effusion


There are several tests used to diagnose a pleural effusion. The doctor will begin by simply listening to your breath sounds through a stethoscope and tapping on your chest to hear how sound is carried through your chest cavity. In addition to this manual diagnosis, you may be required to take one or more of the following rests:

 Chest x-ray;
 Thoracic, or chest region, CT scan;
 Ultrasound of the chest;
 Pleural fluid analysis, in which fluid is drawn out from your lungs
 Thoracentesis, which determines the cause and type of the effusion through drawing fluid out through a needle inserted between the ribs.


Once it has been determined that you have a pleural effusion, and what the cause of the effusion is, treatment is possible. Treatment can be directed in three ways: removing the fluid from the pleural cavity, preventing further accumulation of fluid, or addressing the original cause of the build-up. If the built up fluid is causing you problems breathing, your doctor may draw fluid out through several more thoracentesis treatments. You may be treated with NSAIDs or with antibiotics if your fluid accumulation is due to an inflammation or infection. If your pleural effusion is a secondary symptom of a different illness, your doctor will want to treat that. One common example is congestive heart failure, which sometimes results in pleural effusions, but is treated with diuretics and other treatments for congestive heart failure. In some cases, a chest tube can be implanted to help with the draining of pleural fluid.


Even with treatments available, complications do sometimes arise if you suffer from a pleural effusion. If a lung is surrounded by fluid for a prolonged amount of time, that lung may collapse. If the pleural fluid is the result of an infection, or if it becomes infected itself, it may turn into an abscess, or infected spot. This is called an empyema, and is treated with prolonged drainage with a chest tube placed into the abscess. In addition, air could get into the chest cavity, making your symptoms worse, or surgery could be required to remove the abscess.

When the cause of the effusion can be accurately determined, and when it is treated quickly and efficiently, then there is not reason why the effusion should not clear up and why it should ever again occur. In fact, sometimes effusions leave scar tissue, and this tissue makes it difficult for new effusions to develop. The most important step for overcoming the problems caused by pleural effusion is to make sure the underlying cause is identified. If so, you should be able to treat it.
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