Pus in the thorax: management of empyema and lung abscess

Abstract

Pleural infection is a common clinical problem that is associated with a high mortality and morbidity. In the UK, the mortality is 20% with 20% requiring surgery. The development of an empyema associated with pneumonia is a progressive process classified in three stages. Initially, there is a free-flowing exudate with a normal pH termed a simple parapneumonic effusion. This progresses to a fibrinopurulent stage with increasing fluid and bacterial invasion causing a decrease in pH. If the fluid is clear but the pH ,7.2, this is termed a complicated parapneumonic effusion while frank pus is termed an empyema. The third stage is an organizing stage with the formation of a solid fibrous peel. Pleural infection can also occur after pleural interventions, thoracic or oesophageal surgery, trauma, or oesophageal rupture.