Pleural effusion occurs when fluid builds up in the space between the lining of the lung and the lining of the chest cavity. The lungs and chest cavity are lined by tissues called pleura. It’s normal for a little bit of fluid to be present in these tissues to help with normal breathing. Pleural effusion is an excessive amount of fluid build-up in these tissues.
A wide variety of health conditions can cause pleural effusion. The seriousness of the case depends on how breathing is affected, if the pleural effusion can be treated, and what the cause of pleural effusion is in the first place. People may also hear pleural effusion referred to as “water on the lungs” or “fluid on the lungs”.
Often, there are no symptoms at all. In these cases, the pleural effusion is discovered when someone needs to have a chest X-ray for an unrelated reason.
When there are symptoms, the most common one is shortness of breath. Other symptoms include:
To understand the causes of pleural effusion, it is important to understand the two types of pleural effusion. A pleural effusion can be a build-up of watery fluid (transudative). This type of pleural effusion happens for two reasons: high blood pressure in blood vessels in the lungs or low protein levels in the blood.
The most common causes of watery pleural effusion are:
A pleural effusion can also be a build-up of protein-rich fluid (exudative). This type of pleural effusion happens due to blocked blood vessels or inflamed blood vessels in the lungs.
The most common causes of protein-rich pleural effusion are:
Other causes of pleural effusion that are less common include:
Risk factors for pleural effusion include:
While a doctor will use a medical history and physical exam findings to inform their diagnosis, they will have to order some imaging tests to know whether or not you are experiencing pleural effusion.
A chest x-ray, computerised tomography (CT) scan, and chest ultrasound are all potential tests your doctor will order. They may also ask for a sample of the excess fluid. A doctor will run tests on the fluid to look for tumour growth, infection, protein levels, and signs of abnormal liver and kidney function.
Potential complications of pleural effusion include:
Treatment of pleural effusion is based on 3 goals: fluid removal, prevention of future fluid build-up, and understanding the cause of fluid build-up.
In cases where the person is having trouble breathing, treatment may require placement of a chest tube to drain the fluid. If the fluid build-up is caused by heart failure, water pills (diuretics) may be used. When a patient has cancer or an infection, the first approach is typically chemotherapy, antibiotics or antiviral medications, or other medication treatment.
In some cases, a pleural effusion is resistant to treatment and a person may experience pleural effusion regularly. A medical professional may suggest the use of a drug that causes scarring of the lining of the lungs. This treatment is shown to prevent future pleural effusions in patients who are resistant to other treatments. In severe cases, surgery may be recommended.