Empyema thoracis or pleural empyema is collection of pus in the space between the pleural layers. It is commonly referred to as pus around the lungs. An empyema results from pus-forming (suppurative) infection of the pleural space and is one of the most common causes for exudative type of pleural effusion (fluid around the lungs). An empyema can become chronic due to inadequacy or failure of management of acute empyema.
Diagnosis of Pleural Empyema
The diagnosis of an empyema thoracis is done based on clinical features and the laboratory findings. The clinical features of empyema usually begin with symptoms of lung infection. It includes cough with sputum production and fever which is usually of high grade. This is followed by features of pleural effusion like difficulty in breathing. The patient will also have generalized symptoms like loss of appetite and weakness. Chronic empyema is particularly associated with anemia, lethargy and weight loss.
Chest X-Ray and CT Scan
Radiological investigations include chest radiography and CT scan of chest. The pleural effusion can be seen on chest radiography. Chest radiography can also demonstrate features of chronic empyema. It can be seen as opaque shadows where the pleura is thickened.
Chest CT may be used to demonstrate development of loculations in the effusion, the exact location and the quantity of the pus collected. In chronic empyema CT scan of the chest can be of use in localizing the empyema cavity with a high degree of accuracy. It can also help in defining the extent of pleural thickening.
Diagnostic Pleural Tap
A diagnostic pleural tap is performed ideally before initiation of antibiotic therapy. The pleural fluid in empyema is turbid in appearance. It usually has increased white blood cell count with predominance of neutrophils in empyema of bacterial origin. In empyema resulting from tuberculosis, the white blood cells are predominantly lymphocytes.
Biochemical tests for protein, amylase, glucose and lactose dehydrogenase are performed in the pleural fluid. The pH of the fluid is also tested. In empyema the pH is usually lower than 7.3. Staining is done to identify the microorganisms and may be followed by a culture for a more accurate diagnosis.
Treatment of Empyema Thoracis
The basic aim of the treatment of empyema thoracis is that all interventions should target rapid and effective drainage of pleural pus collection, with complete recovery of lung function. Judicious treatment approaches can result in decreased morbidity and mortality from empyema.
Therapeutic Pleural Tap
The standard approach in treatment of empyema is drainage of the pus collected in the pleural space and antibiotic therapy. In patients with acute empyema, a diagnostic pleural tap may be extended as a therapeutic pleural tap to drain the pus completely from the pleural space. Empirical antibiotic therapy is ideally not initiated until the diagnostic pleural tap is completed. The empirical antibiotic therapy is changed to specific antibiotic therapy once the culture report of the pus is obtained.
If pleural tap fails or if it is not a feasible option, tube thoracostomy is done for the drainage of the pus in pleural cavity.
Video assisted thoracic surgery (VATS) drainage of empyema allows a more complete pleural drainage by direct visualization and breaking down of the loculations in patients failing the tube drainage.
Open thoracic surgery or thoracotomy with drainage of the pus is performed in patients repeatedly not responding to other approaches. Complicated empyema patients are treated with prompt and complete drainage with removal (debridement) of all infected tissues. This should be well supported with prolonged antibiotic therapy.
Chronic empyema is often treated with open surgical approaches. Empyema pus removal and debridement by thoracostomy with resection of the ribs at the most dependent part of the pus collection is a common approach. It may also be done by a full thoracotomy. A tube drain is then used following the pus removal. This allows the eventual constriction and obliteration of the empyema cavity. Some patients require resection of pleura for improvement of lung function. Patients with lung tissue destroyed by any underlying disease may be treated with removal of the pleura and the destroyed lung tissue.