Pulmonary Empyema
Pulmonary empyema is the presence of purulent material in the pleural cavity as a consequence of its infection.
Symptoms and Causes
The most common cause of its formation is a history of bacterial pneumonia (with Staphylococcus aureus and Streptococcus pneumoniae being the most frequent), but other etiologies can also be found, such as mediastinal pathology, esophageal rupture, prior thoracic surgery, subdiaphragmatic processes, as well as related risk factors such as COPD, bronchiectasis, episodes of aspiration, and immune system depression.
Complicated pleural effusion as a result of infection usually occurs in three phases:
- Exudative Phase: This occurs in the first 72 hours and is due to increased permeability of pulmonary capillaries, leading to a greater passage of fluid into the pulmonary interstitium. The fluid is usually clear.
- Fibrinopurulent Phase: From the third to the fifth day, there is increased production of inflammatory cells with a rise in fibrin deposits in the pleural space, thus beginning the formation of collections, as well as a limiting membrane around the lung. The pleural fluid becomes cloudy or purulent.
- Organized Phase: This occurs between the second and sixth weeks; fibroblasts continue to form fibrous membranes until a thick, rigid shell forms around the lung, restricting respiratory movements.
Empyema is typically associated with phases 2 and 3.
Symptoms
The clinical presentation is similar to pneumonia, along with the appearance of nonspecific pleural effusion. The symptoms are usually:
- Cough, productive or not.
- Persistent fever despite appropriate antibiotic treatment.
- Chest pain.
The most frequent signs on physical examination are tachypnea, absence of breath sounds, and dullness on chest percussion.
Complications
Pleural empyema can cause severe damage to the lungs, such as thickening of the pleura or reduced lung function. In severe cases, it can lead to sepsis and septic shock, factors that increase the risk of death.
Prevention
Empyema is a condition that can be prevented with appropriate treatment of lung diseases. For patients with risk factors, vaccination against streptococcus and influenza B is recommended.
Which doctor treats pulmonary empyema?
Pulmonary empyema is usually diagnosed and treated by specialists in pulmonology and thoracic surgery.
Diagnosis
A proper anamnesis and physical examination are necessary to guide the diagnosis and subsequent complementary tests.
The pillars of imaging diagnosis for empyema are chest X-ray, ultrasound, and computed tomography (CT).
- Chest X-ray: Reveals significant pleural effusions but is often difficult to distinguish between empyema or pneumonia.
- Ultrasound: Determines the volume and is more sensitive in characterizing the type of fluid by observing septa (fibrin in the effusion) or loculations (fluid collections that do not communicate), characteristic of complicated pleural effusions and empyemas. It can differentiate pulmonary consolidation from pleural effusion. It is also a good technique to provide the optimal site for drainage placement.
- Computed Tomography: Evaluates the extent of the disease. It shows pleural thickening and enhancement. It is mainly used in patients who do not improve clinically after 48 hours of drainage placement, with suspicion of complications such as abscess formation, improper drainage placement, and broncho-pleural fistula.
Laboratory Analysis of Fluid: To obtain the definitive diagnosis and differentiate paraneumonic pleural effusion from empyema, biochemical study and culture of pleural fluid are used. The latter is the gold standard for diagnosing empyema and guiding antimicrobial treatment, but since it requires days to obtain results and may be negative in 40% of cases, biochemical analysis is used to support the diagnosis. The main parameters used are: pH less than 7.2, glucose less than 20 mg/dL, and LDH > 1,000 IU/L.
The presence of frank pus indicates a diagnosis of empyema, and biochemical tests are not required for this.
Treatment
Early initiation of antibiotic therapy is essential for treating empyema. Once culture results are obtained, targeted antibiotic therapy is recommended. Antimicrobial treatment should be continued for at least 4 weeks.
Additionally, pleural drainage insertion is one of the mainstays of treatment, as delaying this procedure leads to an increase in mortality.
Failure of antibiotic therapy and drainage can be due to the presence of fibrin septa and increased viscosity of the fluid. Therefore, after confirmation of loculated pleural collection, intrapleural fibrinolytic therapy is recommended.
Surgery provides removal of the infection from the pleural cavity and decortication of the visceral pleura to facilitate lung re-expansion. This can be performed using video-assisted thoracoscopic surgery (VATS) or an open thoracotomy. Nowadays, surgery is reserved for cases in which thoracic drainage, antibiotic therapy, and fibrinolytic therapy fail.
