Pleural empyema is a condition in which pus gathers in the area between the lungs and the inner surface of the chest wall. This area is known as the pleural space. Pus is a fluid that is filled with immune cells, dead cells and bacteria. The infected fluid thickens. It can cause the lining of the lungs and chest cavity to stick together and form pockets. This is called an empyema. The lungs may not be able to inflate completely, which can lead to breathing difficulties.
Empyema can be simple or complex. Simple empyema occurs in the early stages of the illness. A person has this type if the pus is free-flowing.Complex empyema occurs in the later stage of the illness. In complex empyema, the inflammation is more severe. Scar tissue may form and divide the chest cavity into smaller cavities. This is called loculation, and it’s more difficult to treat. If the infection continues to get worse, it can lead to the formation of a thick peel over the pleura, called a pleural peel. This peel prevents the lung from expanding. Surgery is required to fix it. In rare instances, a case of complex empyema can lead to more severe complications. These include sepsis and a collapsed lung, also called a pneumothorax.