Pleural Effusion:

• Introduction

One of the most usual symptoms of mesotheloma is a pleural effusion, or an accumulation of fluid between the parietal pleura (the pleura [sac] around the chest wall and diaphragm) and the visceral pleura (the pleura around the lungs). Both of these membranes are enclosed with mesothelial cells which, under routine conditions, generate a small amount of fluid that acts as a lubricant between the chest wall and the lung. Any extra fluid is absorbed by blood and lymph vessels maintaining a balance. When too much fluid forms, the answer is an effusion.

• Types of pleural effusion

Pleural effusion is classified into two types, transudates and exudates. A transudate is a clear fluid that forms not because the pleural surfaces are diseased, but because of an imbalance between the average production and removal of the fluid. The most common cause of transudative fluid is congestive heart failure (CCF). An exudate, which is often cloudy and contains many cells (pus cells) and proteins, results from disease of the pleura itself, and is common to mesotheloma. To verify whether a fluid is a transudate or exudate, a diagnostic thoracentesis, in which a needle or catheter is used to collect a fluid sample, may be conducted.

• Symptoms of pleural effusion

As the amount of fluid increases, shortness of breath, also known as “dyspnea”, and sometimes pain, ranging from mild to acute, may appear. Some patients may experience a dry cough. When the physician listens to the patient’s chest with a stethoscope, normal breath sounds are muffled, and tapping on the chest will show dull rather than hollow sounds.

• Diagnosis of pleural effusion

Diagnosis of pleural effusion is commonly accomplished with a plain chest x-ray, though CT scans or ultrasound (USG) can also be used. A special x-ray, called a lateral decubitus film, may be used to identify smaller effusions or to allow the physician to estimate the amount of fluid present. If the underlying source of the effusion is evident (such as in the case of severe congestive heart failure(CCF)), sampling of the fluid may not be essential, however, because pleural effusion may be symptomatic of a number of disease processes from benign to malignant, a fluid sample is usually taken. Diagnostic thoracentesis, in which cells are extracted from the pleural cavity, is usually done when the possibility of mesotheloma exists, however, in up to 85% of cases, the fluid tests negative or inconclusive even though tumor is present. It is ultimately a needle biopsy of the pleura (lining of the lung) or an open surgical biopsy which confirms a mesothelioma diagnosis.

• Treatment of pleural effusion

Pleural effusion caused by heart failure(CCF) or infection can usually be resolved by directing therapy at the cause, however, when testing has realized no diagnosis, and fluid continues to collect, doctors may advise chest tube drainage and chemical pleurodesis. Chemical pleurodesis is a procedure in which a sclerosing agent is used to abrade the pleural surfaces producing an adhesion between the parietal and visceral pleurae. This will avoid further effusion by eliminating the pleural space. Talc appears to be the most valuable agent for pleurodesis, with a success rate of almost 95%. It is highly effective when administered by whichever poudrage or slurry. Poudrage is the most commonly used technique of instilling talc into the pleural space. Before spraying the talc, the medical team removes all pleural fluid to completely collapse the lung. After the talc is administered, they inspect the pleural space to be sure the talc has been evenly distributed over the pleural space. Some doctors wish to use talc mixed with saline solution which forms wet slurry that can roll around the pleural cavity.

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