Pleural Effusion - What is it?
A pleural effusion is an abnormal or excessive amount of fluid that accumulates around the lungs. In this condition, there is a buildup of fluid between the tissue layers lining the lungs and chest cavity. Pleural effusions may occur as a result of numerous medical conditions. Most pleural effusions are not a cause for serious concern by themselves, although some will entail treatment in order to avoid problems. Pleural effusions are very common with roughly one hundred thousand cases being diagnosed in the US every year, according to the National Cancer Institute. Alternative names for this condition include fluid on the lung, fluid in the chest or pleural fluid.
The lungs are covered by a membrane or lining known as the pleura, which has an outer and an inner layer. The lungs are covered by the inner layer, while the outer layer lines the rib cage and diaphragm – the sheet of muscle that separates the abdomen from the chest. The pleura is responsible for the production of a fluid that serves as a lubricant which assists us in breathing easily, permitting the lung to smoothly move in and out. In certain instances, too much of this fluid may accumulate between the two layers of the pleura. The buildup of fluid then presses on the lung, making it difficult for full expansion of the lung. In certain situations, a section or even the entire lung may collapse. This may cause the patient to become increasingly breathless, not only when they are active, but also while they are resting. It is also common for the patient to experience coughing and chest pain, which are common symptoms of the condition known as pleural effusion. A chest X-ray and/ or an ultrasound scan may be used for the diagnosis of pleural effusions. In some instances, other tests may be required for the confirmation of diagnosis as well as the cause of the effusion.
Should A Pleural Effusion Be A Serious Cause For Concern?
The seriousness of pleural effusion is dependent on the primary cause of the condition, whether it affects the patient’s ability to breathe, as well as whether it can be effectively treated. Pleural effusions that are caused by infection due to viruses, heart failure or pneumonia can be effectively treated or controlled.
Types of Pleural Effusions
There are two main categories of pleural effusions:
- Uncomplicated Pleural Effusion: This type of pleural effusion contains fluid that is free from infection or severe inflammation. A large enough and uncomplicated pleural effusion may result in symptoms. However, it is rare for a pleural effusion to result in permanent lung problems.
- Complicated Pleural Effusion: A complicated pleural effusion contains fluid with a significant amount of infection or inflammation. If left untreated, a complicated pleural effusion may harden thereby forming a constricting ring around the lungs. This process of hardening is referred to as organization and may impair breathing permanently. In order to prevent organization, a complicated pleural effusion will require drainage, usually through a tube that is placed inside the chest.
Pleural effusions may also be described by the following terms: transudative and exudative. Depending on the cause of the pleural effusion, the excess fluid may either be protein-poor (transudative) or protein-rich (exudative). These two categories are able to assist the doctor in determining the cause of the pleural effusion.
Transudative – A transudative pleural effusion occurs as a result of the leakage of fluid into the pleural space. This is due to an increase in pressure in the blood vessels or a low blood protein count. Pleural effusion fluid is similar in character to the fluid that is normally found in the pleural space. A transudative pleural effusion will rarely require drainage, unless it is very large. An example of a condition that may result in transudative pleural effusions is congestive heart failure, which is in fact the most common cause of this condition. Transudative (watery fluid) pleural effusions are commonly caused by:
- Heart failure
- Pulmonary embolism
- Post open heart surgery
Exudative – Pleural effusion fluid contains excess blood, protein or evidence of infection or inflammation. Exudative pleural effusions may require drainage depending on the size and seriousness of the inflammation. Lung cancer and pneumonia are the common causes of exudative pleural effusion. Other causes are blocked lymph vessels and blood vessels, inflammation, tumors and lung injury. Exudative (protein-rich fluid) are commonly caused by:
- Pulmonary embolism
- Inflammatory disease
A doctor can only identify the type of pleural effusion that the patient is suffering from by taking a fluid sample from the pleural effusion.