subject: EMPYEMA AND ITS CLINICAL FEATURES [print this page] EMPYEMA AND ITS CLINICAL FEATURES EMPYEMA AND ITS CLINICAL FEATURES
Empyema refers to infected pleural fluid, whether a turbideffusion or frank pus. In many cases the diagnosisonly becomes apparent on aspiration of the fluid. Mostcommonly, an acute empyema complicates a bacterialpneumonia, particularly pneumococcal, but other causesrequire consideration.
Staphylococcal pneumonia is an important cause in children.Anaerobic infection is sometimes difficult to diagnose,and it is likely that anaerobes are responsible formany 'sterile' empyemas. Tuberculous empyema is nowunusual. It is not uncommon for empyema fluid to containmore than one organism. Empyema following thoracicsurgery, and those associated with abdominal sepsis arefrequently due to Gram-negative organisms. Amoebic liverabscess can rarely perforate the diaphragm and enter thepleural space, as can actinomycosis and hydatid disease.The empyema that occasionally complicates the mediastinitisof oesophageal rupture is usually left-sided.
The clinical features of acute empyema include fever,night sweats and chest pain, with signs of a pleural effusion.The most common clinical setting is that of a pneumoniathat has failed to respond to therapy. The white cellcount is elevated (15000-20000) with a polymorphonuclearleukocytosis. Pleural fluid aspiration is essentialand diagnostic; the fluid may be turbid, with numerouspolymorphs or frank pus. Empyemas are usually posteriorand lateral above the diaphragm. Initially, the pleural fluidmoves freely in the pleural space and the chest X-raydemonstrates the appearances of a simple effusion, but theinfected fluid rapidly becomes loculated and the chestX-ray then shows localized collections of fluid.
An acute empyema can breach the lung and enter abronchus, thereby producing a bronchopleural fistula.Patients then cough large volumes of purulent sputum andon X-ray the empyema has fluid levels. Untreated, anempyema may discharge through the chest wall (empyemanecessitatis). Empyema, particularly when due to staphylococcalinfection, can be complicated by a pneumothorax(pyopneumothorax).
