Empyema

An empyema, also known as a pyothorax, is a collection of pus within the pleural cavity. It must be differentiated from an abscess, which is a collection of pus in a newly formed cavity. Most empyemas arise from an infection within the lung (pneumonia), often associated with parapneumonic effusions.

There are 3 stages: exudative, fibrinopurulent and organizing. In the exudative stage, the pus accumulates. This is followed by the fibrinopurulent stage in which there is loculation of the pleural fluid (the creation of grapelike pus pockets). In the final organizing stage, scarring of the pleural space may lead to lung entrapment.

Symptoms
Symptoms of empyema may vary in severity. Typical symptoms include: fever, chest pain or discomfort, cough, sweating and shortness of breath.

Clubbing of the fingernails may be present. There is a dull percussion note and reduced breath sounds on the affected side of the chest. Other diagnostic tools include chest x-ray, CT scan, and Ultrasonography.

Diagnosis
Diagnosis is confirmed by thoracentesis; frank pus may be aspirated from the pleural space. The pleural fluid typically has a low pH (<7.20), low glucose (<60 mg/dL), and contains infectious organisms.



Treatment
Definitive treatment for empyema entails drainage of the infected pleural fluid. A chest tube may be inserted, often using ultrasound guidance. Intravenous antibiotics are given. If this is insufficient, surgical debridement of the pleural space may be required.