Pathophysiology Of Pleural Effusion Article

Pleural Effusion.

Pleural effusion is a collection of fluid in the pleural space. The pleura line the thoracic cavity (parietal) and the lungs (visceral). The space in between the two linings is the pleural space. When the collected fluid is 300 mls or more, it can show up on an X-ray, and will give a dull percussion sound on examination if there is more than 500ml.

With pleural effusion, there may be reduced movement of the chest wall on the affected side, the structures in the mid-chest (mediastinum) may be displaced away from the effusion and when listening to the lungs with a stethoscope, the breath sounds may be reduced or absent.

For diagnosis, aspiration is done except when the effusion is very small. The effusion can be either exudate or transudate.
Transudates are often bilateral and larger on the right side. This type of pleural effusion is present in heart failure, nephrotic syndrome, constrictive pericarditis, under active thyroid and ovarian tumour.
Exudative type of pleural effusion is found in pneumonia, carcinoma of the bronchus, tuberculosis, acute pancreatitis, post myocardial infarction, mesothelioma and connective tissue disease.

If diagnosis from aspiration is not conclusive, then a pleural biopsy will be done. For effective treatment of pleural effusion, it is necessary to treat the underlying disease causing pleural effusion. An exception to this is empyema which will require drainage.

Malignant Pleural Effusion.

For malignant pleural effusion, the common cause is lung cancer with pleural involvement. This can be the first signs of the cancer and can be substantial in volume (1-4 litres.). It can accumulate quickly and may be blood stained.
Malignant pleural effusion may cause shortness of breath and a dry cough. Examination of the aspirate from the effusion will confirm the presence of cancer cells but often the cytological examination is negative. When there is doubt, a pleural biopsy is done.
Other tumours that can cause malignant pleural effusion are mestastatic lung cancer, mesothelioma and lymphoma. Metastatic lung cancer is more commonly from primary cancers of the breast, ovary and the bronchus.
Once malignant pleural effusion is diagnosed, the primary cause should be identified and treatment of the malignancy should start if feasible.