Empyema

The lungs and inside of the chest cavity are lined with a smooth layer called the pleura. These layers are almost in contact, but separated by athin space the pleural space filled with a small amount of lubricant called pleural fluid.

The pleural fluid cansometimes build up and become infected, so that a collection of pus forms. This can thicken and cause areas of the pleura to stick together, creatingpockets of pus.

Empyema can worsen to become many more pockets of pus, withthick deposits coating the outer layer of the lungs. These deposits prevent the lungs expanding properly.

Pneumonia and other possible causes

The most common cause of empyema is pneumonia caused by a bacterial infection of the lungs. An empyema can form when pneumonia fails to fully respond to treatment in a straightforward way.

Other possible causes are:

• Bronchiectasis ,a long-term condition where the airways of the lungs become abnormally widened, leading to a build-up of mucus that can make the lungs more vulnerable to infection.
• A blood clot or other blockage preventing blood flow to the lungs, causing some of the lung tissue to die. This is known as a pulmonary infarction.
• Surgery to the chest (empyema is a rare complication).
• An endoscopy (empyema is a rare complication).
• A seriousinjury to the chest.
• An infectionelsewhere in the body that hasspread via the bloodstream.
• An infection caused by inhaled food, if you have swallowing problems (but this is rare).
• Tuberculosis (this is rare in the UK).

You're more at risk of developing an empyema if you:

• have diabetes
• havea weakened immune system
• have acid reflux
• drink too much alcohol or take a lot of recreational drugs

Both adults and children can be affected.