Empyema

EmpyemaEmpyema is defined as a collection of pus within the Pleural cavity. This may be as the result of a primary infection or as the result of infection of a pleural effusion or haemothorax. Patients are usually toxic although they may have little in the way of constitutional symptoms. Untreated empyema may complicate by rupture into the lung, by distortion of the mediastinum affecting the opposite lung or by forming an empyema neccesitans with the pus eventually bursting through the skin to drain superficially. Most empyemas form in the posterior pleural cavity, the initial fluid empyema forming in the dependant diaphragmatic recess. Because of this all patients considered to have empyema should have a lateral chest x-ray.

Treatment of empyema

The primary treatment of an empyema is drainage occasionally by aspiration or more usually by means of an under water seal drain. Before any attempt at insertion of a drain is made, a wide bore needle should be inserted in to the empyema space to make sure that pus is aspirated prior to intubation. The most common mistakes are to go too low and through the diaphragm or too laterally and anterior to the collection. Only if pus is located should a drain be inserted. Because of the high incidence of TB in our practice and also to look for possible underlying malignancy we recommend that at the time of drain insertion a pleural biopsy should be performed using an Abram’s pleural biopsy needle. Our unit favours the use of Malecot Drains, inserted using a trochar and cannula. This is because there is less danger of iatrogenic lung and mediastinal injury and the long-term drainage obtained is usually superior to the plastic drains.

A well drained TB empyema space

If pus is very thick it may not drain and a rib resection with pleural toilet may be required or if the patient is fit,elective decortication as definative treatment. Drainage should be continued until the drainage has become minimal and the lung has re-expanded. If there is a thick cortex around the empyema than lung re-expansion may be minimal and decortication may eventually be required. Part of the management of empyema is to investigate the cause. Bronchoscopy is recommended in all patients with empyema to try to rule out underlying pulmonary pathology. Antibiotics are only indicated if the patient has systemic symptoms. Patients with tuberculous empyema should not have prolonged drainage unless the pleural space is secondarily infected or they have a broncho-pleural fistula.