Parapneumonic effusion
A parapneumonic effusion is a type of pleural effusion that arises as a result of a pneumonia. There are three types of parapneumonic effusions: uncomplicated effusions, complicated effusions, and empyema. Uncomplicated effusions generally respond well to appropriate antibiotic treatment. Complicated parapneumonic effusions respond more variably: many resolve with antibiotics but may benefit from early pleural fluid drainage. Treatment of empyemas includes antibiotics, complete pleural fluid drainage, and reexpansion of the lung.
- A parapneumonic effusion is any pleural effusion that is associated with a bacterial pneumonia, lung abscess or bronchiectasis. 40% of all patients with bacterial pneumonia develop a pleural effusion, and the development of a pleural effusion increases morbidity and mortality as compared with an isolated pneumonia. . In general parapneumonic effusions have 3 stages:
- Exudative: Due to capillary leak, causing a sterile effusion that has a poly predominance, with normal glucose and pH. It is seen within the 1st 72, and will usually resolve with antibiotics alone.
- Fibrinopurulent: Occurs during days 3-7. The pleural fluid becomes infected with bacteria, and the lactate dehydrogenase (LDH) rises, as the glucose and pH fall. As the fibroblasts get busy, loculations develop which limits the extension of the empyema.
- Organization: Further fibroblast activity produces a pleural peel leading to restrictive lung disease. Without definitive treatment, the empyema can drain externally (empyema necessitatis) or into the lung to produce a broncho-pleural fistula.
- Approximately 20% of all parapneumonic effusions evolve into empyema. Hippocrates described empyema thoracis around 400 BC and predicted drainage of the pleural cavity as the treatment of choice. The term empyema refers to either the presence of gross pus in the pleural space, or a positive gram stain on pleural fluid analysis. 60% of empyemas evolve from a parapneumonic effusion, 20% after thoracic surgery and 20% from thoracic trauma, esophageal perforation, thoracentesis or subdiaphragmatic infection. The majority of patients who develop empyema have underlying disease, most frequently alcoholism (especially in patients with anaerobic infections), malignancy and diabetes.
References
Duke, J. Roy, Jr. (2000). "Pleural Effusion". Frontline Assessment of Common Pulmonary Presentatons. Denver, CO: Snowdrift Pulmonary Foundation, Inc. ISBN 0-9671809-2-9. Retrieved 2007-08-07. Unknown parameter |coauthors= ignored (help)