pleural effusion

Definition: increased fluid in the pleural space; can cause shortness of breath by compression of the lung and/or increased intrathoracic pressure resulting in mediastinal shift and increased work of breathing; a transudative effusion has low protein content and is usually due to heart failure, uremia, or hypoalbuminemia; an exudative effusion has high protein and cell count and is due most often to inflammation, malignancy, or infection; an infected pleural effusion is an empyema; a pleural effusion associated with pneumonia is a parapneumonic effusion; a pleural effusion without actual infection but with signs of a high degree of inflammation (low pH, low glucose, high lactate dehydrogenase, many white blood cells) is a complex pleural effusion and is frequently associated with pneumonia; a loculated pleural effusion is not free flowing in the pleural space but rather confined to one or more fixed pockets.

Synonym(s): hydrothorax

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