Pleural effusion is a build-up of excess fluid between the lining of the lungs and chest cavity. This lining is called the pleura. The area between the pleura is the pleural space. The body normally produces a small amount of fluid between the pleura to facilitate breathing. A pleural effusion occurs when there is more fluid than normal. The excess of fluid may prevent the lungs from fully expanding. As a result, patients may have hard time breathing. Pleural effusion may be caused by irritation, inflammation or infection of the pleura. Pleural effusion may be a symptom of mesothelioma, lung cancer or other diseases.
Types of Pleural Effusion
There are two types of pleural effusion:
Inflammatory: This is caused by a lung disease like pneumonia or lung cancer, both of which irritates the pleura.
Noninflammatory: This is caused by abnormal fluid pressures inside the lungs. The pressure can be caused by congestive heart failure (CHF). In CHF, extra fluid collects inside the lung tissues because of a weak heart muscle. This extra fluid then leaks into the pleural space. Other causes of noninflammatory pleural effusions include kidney disease, liver disease, and malnutrition.
The pleural space normally contains 0.1–0.2 ml/kg body weight of fluid, filtered from systemic capillaries down a small pressure gradient. Fluid drains into the systemic circulation via a delicate network of lymphatics and eventually enters the mediastinal lymph nodes. Fluid may accumulate in the pleural space by a number of mechanisms: increased pulmonary capillary pressure, decreased (more negative) intrapleural pressure (e.g. atelectasis), decreased plasma oncotic pressure (e.g. hypoalbuminaemia), increased pleural membrane permeability and obstructed lymphatic flow (e.g. pleural malignancy or infection).
The following diseases may cause pleural effusion:
- Heart failure
- Bacterial pneumonia
- lung cancer and other tumours with lung metastases
- Pulmonary embolism
- Radiation therapy to the chest
- Nephrotic syndrome
- Ovarian tumours
- Connective tissue disease (for example, rheumatoid arthritis, lupus)
Rarely: heart attack, acute pancreatitis, mesothelioma, sarcoidosis, yellow-nail syndrome, familial Mediterranean fever.
Causes of Pleural Effusion
There are many causes of a pleural effusion. Depending on the cause, your doctor will determine the treatment option. Common causes include:
Autoimmune disorders – Rheumatoid arthritis or lupus can cause pleural effusions
Cancer – Lung cancer as well as other cancers that have spread to the lung can also result in a pleural effusion
Cirrhosis of the liver – When severe scarring has occurs in the liver due to long term exposure to certain substances such as alcohol, the liver’s function is severely impaired, resulting in a build-up of fluid in the pleural space
Congestive heart failure (CHF) – The most common cause of a pleural effusion, CHF occurs as a result of poor heart function and a decreased ability for the heart to pump blood effectively
Infections – Some diseases caused by viruses or bacteria such as pneumonia or tuberculosis can also lead to a pleural effusion
Previous surgery – A pleural effusion is reasonably common after either heart surgery (often Coronary Artery Bypass Grafting or LVAD implantation) or any lung surgery in that side of the chest
Pulmonary embolism – A blood clot causes a blockage in one of the lungs, which can result in a pleural effusion as a result of poor lung function.
Pleural Effusion Symptoms
The most common pleural effusion symptoms in patients with nonexpandable lung were breathlessness and cough, while chest pain was more common among mesothelioma patients without effusions.
Symptoms of pleural effusion can vary from mild to severe. Some patients experience no symptoms at all. The type and severity of symptoms often correlates with the amount of fluid and any underlying breathing conditions or infections.
Common Pleural Effusion Symptoms
- Dry cough
- Shortness of breath
- Sharp chest pain that worsens with cough or deep breathing
- Malaise (general feeling of discomfort)
- Rapid, shallow breathing
- Fever if fluid becomes infected
Although pleural effusions can resolve on their own, it is best to seek treatment if you have breathing changes or new onset of shortness of breath. The pressure from excess pleural fluid can cause a lung to collapse.
If you don’t seek immediate treatment, pleural fluid may become infected. An infection of the pleural fluid is called empyema.
The potential complications associated with pleural effusion are:
- Lung scarring,
- Pneumothorax (collapse of the lung) as a complication of thoracentesis,
- Empyema (a collection of pus within the pleural space), and
- Sepsis (blood infection) sometimes leading to death.
Diagnosis and test
The Lung Center may conduct the following diagnostic tests and procedures:
Chest CT-scan uses a combination of X-rays and computer technology to produce horizontal, or axial, images of any part of the body, including the bones, muscles, fat, and organs.
Chest X-ray uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs on film or digital media.
Magnetic resonance imaging (MRI) uses a magnetic field and pulses of radio-wave energy to detect changes in the normal structure and characteristics of organs or tissues.
Positron emission tomography (PET) computed tomography and nuclear scanning.
Kidney and liver function blood tests
Thoracentesis, a needle is inserted through the back of the ribcage into the pleural space to remove fluid or air.
Ultrasound of the chest and heart
Pleural biopsy, a procedure in which a sample of the inner lining of the ribcage is removed with a special biopsy needle or during surgery to determine if infection, cancer, or another condition is present. There are three types:
Needle biopsy or thoracentesis removes a fluid sample with a needle inserted between the ribs. Ultrasound or CT-scan may be used to guide the biopsy needle insertion.
Pleural fluid analysis examines the fluid under a microscope to look for bacteria, protein and cancer cells.
Thoracoscopic biopsy- A special type of telescope (thin, flexible, lighted tube) is inserted into the pleural space under general or local anesthesia. With a direct view inside the chest, the doctor is able to visualize the pleural tissue and take a biopsy to determine the cause of the effusion.
Open biopsy- After a general anesthetic is given, your surgeon makes an incision in the skin and surgically removes a piece of the pleura. Depending on the lab findings, further surgery may be performed.
Treatment for Pleural Effusion
Small effusions that cause no symptoms, or only mild symptoms, may just be left and ‘observed’. Treatment is usually only needed if the effusion causes symptoms such as breathlessness.
A large pleural effusion that makes you breathless can be drained. This is called a pleural fluid aspiration or pleural tap. It is usually done by inserting a needle or tube through the chest wall. A local anaesthetic is injected into the skin and chest wall first to make the procedure painless. This may be a ‘one-off’ procedure to relieve symptoms.
However, in many cases, unless the underlying cause can be treated, an effusion is likely to return within a few weeks. Repeated draining of the fluid, when symptoms become troublesome, is one option.
Depending on the underlying cause, other treatment options that are sometimes considered include:
Pleurodesis: In this procedure, a special chemical (a sclerosant) is injected into the pleural space. This causes inflammation of the pleural membranes and helps them to ‘stick’ together. This helps to prevent fluid building up again into an effusion. Sclerosing chemicals that are commonly used include tetracycline, sterile talc and bleomycin. Pleurodesis is most often used in the treatment of repeated (recurrent) effusions caused by cancer.
Leaving a permanent drain in place so the fluid can drain out as and when it forms.
An operation to insert a shunt (like an internal drain) to allow the fluid to drain out from the chest into the tummy (abdominal) cavity. This is called a ‘pleuroperitoneal shunt’. It is only occasionally used.
Pleurectomy: This is an operation to remove the pleura. It is sometimes used in people with effusions due to cancer when other treatment options have failed.
- In some cases, you can prevent pleurisy by preventing the medical condition that causes it. For example, some types of pneumonia can be prevented by vaccination. The risk of lung cancer is reduced by not smoking.
- Not all cases of pleurisy can be prevented.
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