Pleural Effusion
Pleural effusion refers to an abnormal collection of fluid around the lungs.
The pleura is a thin membrane that lines the surface of the lungs and the inner surface of the chest wall. Normally, only a very small amount of watery fluid are present in the pleural space, allowing the lungs to move smoothly within the chest cavity during breathing. In pleural effusions, fluid accumulates in excessive amounts in this space between the layers of pleura. Excessive amounts of such fluid can make breathing difficult by limiting the expansion of the lungs during respiration.
Causes of Pleural Effusions:
A pleural effusion is not a disease in itself, but rather a complication of an underlying illness. It can occur for a variety of reasons, and is commonly classified according to the chemical composition of the fluid causing the effusion, (i) transudate pleural effusions, and (ii) exudate pleural effusions. Sometimes pleural effusions may have characteristics of both a transudate and an exudate.
(i) Transudate Pleural Effusions:
Transudate pleural effusions are formed when fluid leaks from blood vessels into the pleural space. Conditions which may cause transudate pleural effusions include the following:
• Congestive heart failure
• Liver failure or cirrhosis
• End-stage renal failure, Nephrotic syndrome
• Peritoneal dialysis
(ii) Exudate Pleural Effusions:
Exudate pleural effusions are caused by inflammation of the pleura itself and are often due to an underlying disease of the lung.
Examples include:
• Lung cancer
• Pneumonia
• Tuberculosis
• Post-pericardotomy syndrome
• Systemic lupus erythematosus (SLE)
• Lymphoma
• Pancreatic pseudocyst
• Ascites
• Abscess in the intra-abdominal cavity
• Asbestosis and mesothelioma
Symptoms of Pleural Effusions:
Small pleural effusions often cause no symptoms. Symptoms are more likely when a pleural effusion is moderate or large, or if inflammation is present, and typical symptoms include:
Shortness of breath: the larger the effusion, the more difficult it is for the lung to expand, and the more difficult it is to breathe.
Chest pain: occurs because the pleural lining of the lung is irritated. The pain is usually described as pleuritic, defined as a sharp pain, worsening with a deep breath.
Other symptoms may be related to the underlying condition which is causing the effusion.
For example, individuals with:
Congestive heart failure may complain of swelling of their feet and shortness of breath when laying flat, (orthopnea) or wakening them in the middle of the night (paroxysmal nocturnal dyspnea)
Tuberculosis may be have night sweats, chills and rigors, coughing up of blood (hemoptysis), and loss of weight
Pneumonia may complain of fever, chills, a productive cough and pleuritic chest pain.
Diagnosis:
Pleural effusion is usually diagnosed on the basis of a good medical history and thorough physical examination, and confirmed by imaging (chest X-ray, computed tomography or ultrasound). Once accumulated fluid is more than 300 ml, there are usually detectable clinical signs, such as decreased movement of the chest, dullness to percussion over the fluid, diminished breath sounds, decreased vocal resonance and fremitus, and pleural friction rub on the affected side. If the effusion is large, there may be deviation of the trachea to the opposite side.
Once a pleural effusion is identified on imaging, a fluid sample is usually taken to determine its characteristics. In a procedure called a thoracentesis, the doctor inserts a needle and a catheter between the ribs, into the pleural space and a small amount of fluid is withdrawn for testing. In larger effusions, a chest-tube may be inserted, and some of the fluid drained may be sent for testing as well.
Treatment:
Treatment of a pleural effusion will have to include treating the underlying cause as well. For example, giving antibiotics for an underlying pneumonia or a diuretic agent in congestive heart failure.
For small effusions, simple needle aspiration may be all that is required. Larger effusions may require insertion of a chest-tube. Repeated effusions may require chemical (talc, bleomycin, tetracycline/doxycycline), or surgical pleurodesis, in which the two pleural surfaces are scarred to each other so that no more fluid can accumulate between them. Pleurodesis involves inserting a chest tube, then either mechanically abrading the pleura or inserting the chemicals to induce a scar. Pleurodesis fails in as many as 30% of cases.
Further Reading
The article above is meant to provide general information and does not replace a doctor's consultation.
Please see your doctor for professional advice.