Empyema is pus in the pleural space.
The most common cause of empyema is pneumonia with spread of infection to an associated effusion. A lung abscess can also spread to the pleural space. Exogenous infection may be from a penetrating injury or be iatrogenic, e.g. following chest drain insertion for an effusion. Endogenous infection may be from perforated oesophagus or spread from a subphrenic abscess.
Initially the pleural space is filled with a thin watery fluid containing pus cells (purulent effusion). There is then laying down of fibrin between the parietal and visceral pleura, which may become organised to form a thick fibrous wall around the pus filled cavity.
Patients present with similar features to a pleural effusion: dullness to percussion, absence of breath sounds. They often appear generally unwell with tachycardia, tachypnoea and pyrexia.
There is a leucocytosis and X-ray shows a pleural opacity classically posteriorly with a D shaped outline. Needle aspiration is used to obtain fluid for microscopy, culture and sensitivities.
The aim of therapy is to drain the fluid and expand the lungs whilst treating the infection with appropriate empirical antibiotics initially. Antibiotics are tailored according to microbiology results from the fluid.
· In the early stages needle aspiration may be adequate.
· For thicker pus an ntercostals drain may have to be inserted.
· In some patients, videoscopic assisted thorascopic surgery (VATS) or open thoracotomy and removal of the walls of the empyema is needed for complete resolution, particularly if the effusion is loculated.