Define Empyema Thoracis. Describe its aetiology, stages, clinical features and investigations.

Definition

• Empyema thoracis is the collection of pus in the pleural cavity.
• In children it is most often a complication of bacterial pneumonia (a 'parapneumonic effusion' that becomes infected).

Etiology

• Staphylococcus aureus (classic, especially in infants), Streptococcus pneumoniae, and Streptococcus pyogenes.
• Tuberculosis and Gram-negative organisms in specific settings.

Stages

• Exudative stage — thin, free-flowing fluid.
• Fibrinopurulent stage — thick pus with fibrin strands and loculations.
• Organising stage — a thick fibrous 'peel' traps the lung.

Clinical Features

• Persistent or swinging fever despite antibiotics for pneumonia, with toxaemia.
• Respiratory distress, chest pain, and reduced movement of the affected side.
• Signs — stony dull percussion note, reduced breath sounds and reduced vocal resonance on the affected side; mediastinal shift to the opposite side.

Investigations

• Chest X-ray — homogeneous opacity with a fluid level / obliterated costophrenic angle.
• Ultrasound of the chest — confirms fluid, detects loculations, and guides tapping.
• Pleural fluid aspiration & analysis — frank pus; sent for cell count, biochemistry, Gram stain, culture and AFB/TB testing.

Management

• Appropriate IV antibiotics (covering Staph & pneumococcus) for a prolonged course.
• Drainage — intercostal chest-tube (closed) drainage is the mainstay.
• Intrapleural fibrinolytics for loculated collections; surgery (decortication / VATS) for the organised stage or failed drainage.
• Supportive care — nutrition, oxygen, and treatment of the underlying pneumonia.

Empyema VS Simple Effusion

• A simple parapneumonic effusion is thin, sterile fluid; an empyema is frank pus with a low pH and glucose and a high LDH on pleural analysis.
• Ultrasound distinguishes free from loculated fluid and guides drainage.

Prognosis

With timely antibiotics and drainage, most children recover fully with good lung function; delay leads to a thick pleural peel needing decortication.

Early drainage prevents progression to organisation.