Pleural effusion

Pleural effusion

Definition

A pleural effusion is defined as an accumulation of fluid in the pleural space.

Aetiology

The effusion is classified as transudate or exudate based on the protein content (see Table 3.15).

Clinical features

Symptoms include shortness of breath and chest pain. Signs of an effusion are only present when >500 mL of fluid is present and include reduced chest expansion on the affected side, stony dull percussion note, reduced or absent breath sounds and vocal resonance.

Investigations

1. Chest X-ray: visible when there is >300 mL, ranges from blunting of the costophrenic angles to dense homogeneous shadow, usually with a meniscus. Mediastinal shift occurs with massive effusion.

2. Diagnostic pleural aspiration with needle and syringe:

-Biochemistry allows the separation into a transudate and an exudate on the basis of protein content. A pH of less than 7.3 is suggestive of empyema, but may also occur in malignancy, rheumatoid and TB. Microbiology if the aspirate is turbid and to search for an infective course.

-   Blood-staining suggests pulmonary infarction or malignancy.

-   Cytology to detect neoplastic cells, and distinguish acute from chronic inflammation on the basis of the cellular infiltrate.

3. Pleural biopsy if needed: particularly for suspected mesothelioma and TB.

Management

Is aimed at the underlying cause thus identification is of primary importance. Large effusions can be treated by aspiration or chest drainage, but too rapid drainage can cause pain and even pulmonary oedema and hypotension. Recurrent malignant effusions can be treated with chemical or surgical pleuradhesis.