PLEURAL EFFUSION

55 PLEURAL EFFUSION



General Discussion


Potential mechanisms of pleural fluid accumulation include increased interstitial fluid in the lungs secondary to increased pulmonary capillary pressure or permeability, decreased intrapleural pressure, decreased plasma oncotic pressure, increased pleural membrane permeability, obstructed lymphatic flow, diaphragmatic defects, and thoracic duct rupture. The most common causes in adults are heart failure, malignancy, pneumonia, tuberculosis, and pulmonary embolism. Heart failure is the most common cause of bilateral pleural effusion. However, if cardiomegaly is not seen with bilateral pleural effusion, other causes such as malignancy should be pursued.


The first step in identifying the underlying cause of a pleural effusion is determining whether the effusion is exudative or transudative. Thoracentesis should be performed in all patients with more than a minimal pleural effusion unless heart failure is the clear diagnosis. If heart failure is present, thoracentesis may be indicated if atypical circumstances are present such as fevers, pleuritic chest pain, unilateral effusion, effusions of markedly disparate size, cardiomegaly is not present, or if the effusion does not respond to treatment for heart failure.


Exudative effusions can be differentiated from transudative effusions using Light’s criteria. Light’s criteria are nearly 100% sensitive at identifying exudates. An effusion is an exudate if one or more of the following criteria are present:


• Pleural fluid lactate dehydrogenase (LDH) >two-thirds the upper limit of normal for serum LDH, or

• Pleural fluid-to-serum LDH ratio > 0.6, or

• Pleural fluid-to-serum protein ratio > 0.5

A patient with heart failure who has received diuretics may fulfill criteria for an exudative effusion. In this case, if the difference between protein levels in the serum and the pleural fluid is greater than 3.1 g/dL, the patient actually has a transudative effusion.


Additional tests used to identify an exudative pleural effusion include the following:


• Pleural fluid-serum albumin gradient >1.2 g/dL

• Pleural fluid-to-serum cholesterol ratio > 0.3

Any drug should be considered as a potential cause for an undiagnosed exudative effusion before pursuing an extensive diagnostic evaluation. The presentation of drug-induced pleural disease may vary from an asymptomatic pleural effusion to acute pleuritis to symptomatic pleural thickening. Pleural disease due to medications may occur as a result of hypersensitivity or allergic reaction, direct toxic effect, increased oxygen free radical production, suppression of antioxidant defenses, or chemical-induced inflammation. Pleural fluid eosinophilia, defined as > 10% of nucleated cells, may provide evidence for the presence of drug-induced pleural disease. However, the presence or absence of eosinophilia in the pleural fluid is a nonspecific finding. Other causes of pleural fluid eosinophilia include pneumothorax, fungal disease, parasitic infection, hemothorax, Hodgkin’s lymphoma, benign asbestos pleural effusion, and pulmonary emboli with pulmonary infarction.



Medications Associated with Pleural Effusion



Absolute alcohol

Acyclovir

Amiodarone

Bleomycin

Bromocriptine

Clozapine

Cyclophosphamide

Dantrolene

Docetaxel

D-penicillamine

Gliclazide

Granulocyte colony-stimulating factor (G-CSF)

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Aug 17, 2016 | Posted by in PEDIATRICS | Comments Off on PLEURAL EFFUSION

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