What is Pleural Effusion?
Accumulation of fluid in the pleural space, which is an area between the tissue layers lining the chest cavity and the lungs, is known as Pleural Effusion. Pleural Effusion is also known as Pulmonary Effusion. The fluid which gets accumulated in pleural effusion can be categorized as exudate or transudate.
Exudate is produced as a result of inflammatory conditions, such as lung infection or lung cancer. Exudative pleural effusions are often serious and difficult to treat. Transudate is made of ultrafiltrates of plasma and is produced due to an imbalance in oncotic and vascular hydrostatic pressure in the chest which can be seen in conditions, such as cirrhosis and heart failure.
What are the Causes of Pleural Effusion?
Some of the major causes of pleural effusion are: congestive heart failure, infection, kidney failure, malignancy, hypoalbuminemia, pulmonary embolism, trauma and cirrhosis.
Pleural effusion develops as a result of seeping of the fluid into the pleural space which is a narrow area between the pleural and visceral membranes in the chest cavity. A small amount of fluid is normally present in the pleural space to help facilitate smooth movement of the lungs. Fluid under pressure, infectious agents and malignant cells can sometimes invade the pleural space and causes it to expand with increased quantities of fluid and other components.
What are the Symptoms of Pleural Effusion?
Chest pain, breathing difficulties, pain with breathing (pleurisy), and cough (dry or productive) are some of the common symptoms of pleural effusion. Pain increases with deep breathing. If the pleural effusion is caused by infection, then patient will experience symptoms such as fever, chills, and appetite loss.
Risk Factors of Pleural Effusion
The cause of pleural effusions could be any underlying medical problems. So the risk factors of pleural effusions are the medical conditions listed in the causes. However, not all patients with these medical problems will have pleural effusion. Malignancy and infection (pneumonia) are the commonest causes of exudative pleural effusions; whereas, congestive heart failure is the commonest cause of transudative pleural effusions.
How is the Diagnosis of Pleural Effusion made?
- Patient's medical history and physical exam are done and this help in diagnosis of pleural effusion.
- Patients with history of cirrhosis or congestive heart failure and symptoms of difficulty in breathing, cough and pleuritic chest pain are an indication towards pleural effusion.
Physical exam findings consist of dullness to percussion in the lung region, decreased vibration and there is asymmetrical chest expansion with unequal inflation or deflation of the lungs.
- Auscultation reveals decreased or inaudible breath sounds on the affected region.
- Auscultation also reveals egophony where there is increased resonance of the voice and a friction rub can also be heard; because of the fluid present in the pleural space, the heart will rub against the space which is filled with fluid or the inflamed space producing a friction rub.
- Chest x-ray is done to confirm the diagnosis of pleural effusions. Pleural effusion appears as whitish areas at the base of the lung. They can be unilateral or bilateral. When a person lies on one side for some time, then the majority of the pleural effusions tend to move and spread out on the side of the chest cavity which facing downwards. This shifting of the pleural effusion can be seen on an x-ray when taken with the patient lying on their side.
- CT scan can be done to identify the cause and the extent of pleural effusion.
- To diagnose the cause of pleural effusion, the doctor first needs to determine if the fluid is exudate or transudate. Fluid analysis is done for this and this is important, as the results will determine the cause of pleural effusion and determine the course of treatment.
- Thoracentesis is a procedure where the fluid is removed from pleural space and sent to laboratory for analysis. Blood tests such as LDH, protein, glucose, cholesterol and pH are done and the results are compared with the results of Thoracentesis.
- Other pleural fluid testing consists of cytology, cell count and cultures.
What is the Criteria Used for Differentiating Exudate from Transudate?
The criteria used for differentiating exudate fluid from transudate fluid consist of:
The following are the characteristics of exudate:
- The pleural fluid protein level is greater than 2.9g/dL.
- The pleural fluid LDH is greater than 0.45 of the upper parameter of normal blood values.
- Pleural fluid cholesterol level is greater than 45mg/dL.
- Different criteria can be used by other health care professionals to determine the presence of exudate. Results of other pleural fluid tests such as amylase or cytology can also help reveal the source of the effusion.
How is Pleural Effusion Treated?
No Treatment: Treatment is not needed if there are small transudative pleural effusions; however, treatment is required for large pleural effusions and exudative pleural effusions.
Thoracentesis for Treating Pleural Effusion: Drainage of the pleural fluid is the first line of treatment, which is done by thoracentesis. Thoracentesis not only helps with diagnosis, but also acts as treatment in pleural effusion. In thoracentesis, a tube is inserted into the pleural cavity and the effusion is drained out. This procedure should be done by an experienced doctor. For continued drainage, the tube needs to remain in the pleural space for longer duration.
Thoracentesis may need to be repeated and this differs from patient to patient and also depends on the amount of effusion fluid, the underlying cause, the type of effusion (thin, thick, infectious, malignant) and whether there is recurrence of pleural effusion.
Medications for Treating Pleural Effusion: Medications for pleural effusions are prescribed depending on its underlying cause. If infection is the cause of pleural effusion, then antibiotics are prescribed. Diuretics are also prescribed to decrease the amount of pleural effusion.
Surgery for Treating Pleural Effusion: Surgery may be needed in some pleural effusions, often in exudative type, to break up the adhesions. Some effusions may need pleurodesis, which is a procedure which obliterates the pleural space. Different irritants and medications are used in pleurodesis for scarring or fibrosing the pleural and visceral surfaces together. Pleurodesis seals the pleural space so there is difficulty in building up of pleural effusion again.
What are the Complications of Pleural Effusion?
Given below are some potential complications of pleural effusion:
- Scarring of the lung.
- Empyema where there is accumulation of pus in the pleural space.
- Pneumothorax where the lung collapses. This occurs as a complication of thoracentesis.
- Sepsis or blood infection is a fatal complication which can even cause death of the patient.
Prevention of Pleural Effusion
Treating the underlying cause of pleural effusions helps in preventing the development of pleural effusions. But in some patients, it is not possible to prevent the development of pleural effusions. Recurrence of pleural effusions can be prevented by undergoing pleurodesis which is a procedure that obliterates the pleural space.