Pleural Effusion

Pleural Effusion
Abdelsadek Al-Aarag
Prof. of Chest Diseases ,
Faculty of Medicine,
Benha University
It is the accumulation of fluid inside the pleural cavity.
Fluid may accumulate in the pleural space by transudation or exudation in a wide variety of conditions.Pathogenesis: In health there is a very thin film of fluid in the pleural space, amounting in total to 1 or 2 ml, which is produced by exudation of fluid from sub-pleural capillaries and absorbed into pleurallymphatics. Pleural effusions may arise if any ofthe following occur: 1-Pulmonary capillary wedgepressure is increased. 2-Pleural capillary permeability isincreased by inflammation. 3-Pleural lymphatic absorption isdecreased. 4-Plasma osmotic pressure isdecreased. Pleural effusions may be dividedinto exudates and transudates. EXUDATES are caused by pleural inflammation, impaired lymphatic absorption, or increased permeability. A large effusion usually results with a high protein content (>3.5 g/dl ) and highspecific gravity (> 1015). TRANSUDATES are caused by passive transudation of fluid into the pleural space by increase in pulmonary capillary pressure in congestive heart failure, loss of plasma oncotic pressure with hypoproteinaemia in nephritic syndrome and liver cirrhosis. Transudates have a low protein content ( Physical examination: A small pleural effusion may be undetectable, but if 500ml or more of fluid are present, chest wall movement is reduced, vocal fremitus is absent, stony dullness is present and breath sounds and vocal resonance are reduced over the effusion. Occasionally bronchial breathing may be heared at theupper border of effusion.Investigations: RADIOLOGY:1- Chest X-RAY. The smallest effusion presents as obliteration of the costophrenic angle. With larger effusion a dense homogenous opacity is visible in the lower part of the chest obliterating the costophrenic angle and rising to the axilla. The shadow extends higher at the chest margin because the sheet of fluid is here presenting a greater obstruction to the transmission of X-rays. Massive effusions may cause displacement of the mediastinum. If loculation occurs a semicircular opacity may be seen on the lateral chest wall, in the paravertebral gutter or in the interlobar fissure as an elliptical opacity. Films taken in the lateral decubitus position will show whether fluid is freely mobile in thepleural space or not. 2- Ultrasound imaging is helpful in localizing loculated effusions and inpositioning chest tubes. 3- Computed tomography(CT) may be required to assess theunderlying lung and mediastinum. ASPIRATION: is essential as examination of fluid may reveal the diagnosis. The needle should be inserted under local anaesthesia into the midscapular line, one intercostal space below the point of maximal dullness to percussion. Care must be taken to prevent air entering the pleural space during aspiration. Not more than 1500 ml of fluid should be removed at any aspiration to avoid the risk of inducing re-expansion pulmonary edema. The colour, specific gravity, protein and glucose content and cytology of the fluid should be noted and the aspirated fluid should be cultured for microorganisms including mycobacteria. Pleural biopsy may be performed at the time of aspiration using an Abram”s pleural punch biopsy (blind biopsy) or using medical thoracoscopy (biopsy under vision) but the two should not be attempted unlessfluid is present to avoid lung injury. Further investigations e.g bronchoscopy for suspected lung cancer or ultrasound of abdomen for suspected subphrenic abscess may be required depending on the clues to diagnosis elicited on initialassessment. Clinical Features and Treatment of Different Types of PleuralEffusion 1-POST-PNEUMONIOC EFFUSION: Usually small, secondary to bacterial pneumonia with a history of recent infection, pleuritic pain and fever. The fluid is clear or straw- coloured and usually sterile on culture if antibiotics have already been given. When cellular examination is done , polymorphsusually predominate. 2-TUBERCULOSIS: Pleural effusions occur within 6 months of the onset of pulmonary tuberculosis and are rare in young children. Pleural biopsy should always be attempted in cases of suspected tuberculosis witheffusion. The fluid is usually straw- coloured and the predominat cellsare lymphocytes. 3-MALIGNANCY: a-Bronchial Carcinoma. Effusion is usually secondary to infection distal to a carcinoma. Less commomnly the pleura may be involved by direct invasion withtumour. b-Metastatic Carcinoma. Especially from breast or bowel, less commonly give rise to pleuraleffusion. c-Pleural Mesothelioma. Pleural effusion is a common feature ofmesothelioma. In general, malignant effusions re-accumulate rapidly after aspiration. The fluid which is usually blood-stained should be examined for malignant cells and pleural biopsy should be performed. Re-accumulation of pleural effusion may be prevented by Pleurodesis (instillation of sclerosing material such as bleomycin, talc poweder) into the pleural space after removalof the fluid. 4-COLLAGEN DISEASES: Pleural effusions are quite common, especially with rheumatoid disease, where characteristically the clear fluid has a low glucose content anda high lactic dehydrogenase. 5-CONGESTIVE HEART FAILURE: Small pleural transudate is a common complication of sever congestive heart failure. Spontaneous resolution with diuretic therapy is usual andaspiration is not necessary.