What causes empyema?
Empyema is caused by an infection that often spreads from the lungs following pneumonia. It can cause an accumulation of a large quantity of pus and fluid in the cavity between the lungs and their membrane. A subdural empyema may result from a sinus infection, a severe ear infection, a head injury, surgery, or a blood infection that develops after a lung infection. The same kinds of bacteria that cause brain abscesses can cause subdural empyemas. The formation of the empyema is conventionally divided into three phases: exudative, fibrinopurulent and organizing. During the exudative phase, the pus accumulates. This is followed by the fibrinopurulent phase in which there is loculation of the pleural fluid (the creation of grapelike pockets of pus). In the final organizing phase there is the potential for lung entrapment by scarring.
