Empyema causes, symptoms, types, diagnosis and treatment

Empyema refers to the accumulation of pus in a body cavity, most commonly in the pleural space (the area between the lungs and the chest wall). It typically occurs as a complication of an infection, such as pneumonia, or following trauma or surgery.

Empyema

Pus in the pleural space or infected pleural fluid occurring as a complication of:

1. Direct spread from adjacent bacterial pneumonia.
2. Rupture of a lung abscess into the pleural space
3. Invasion from subphrenic collection
4. Traumatic penetration.
5. Blood or lymphatic seeding of the pleura in systemic infection.
6. Bacterial organisms include pneumococci, hemolytic streptococci, staphylococci aureus and gram-negative, especially with anaerobes.

Empyema is either acute or chronic (> 3 months) and loculated or free in the pleural space. This is decided by the nature of the invading organism or host defense mechanisms.

1. Streptococcal empyema is usually free in the pleural space due to the liberation of the lysing enzyme {streptokinase).
2. Pneumococcal empyema is characterized by early adhesions
3. Staphylococcal empyema is intermediate between both forms.

Causes of Empyema

1. Infections:

• Most common: Pneumonia, particularly when caused by bacteria like Streptococcus pneumoniae, Staphylococcus aureus, or Klebsiella.
• Tuberculosis.
• Post-surgical infections or post-trauma.

Other Triggers:

• Lung abscess rupture into the pleural space.
• Esophageal rupture.
• Complications of thoracic surgeries or chest trauma.

Symptoms

• Fever and chills.
• Chest pain: Sharp and worse with deep breathing (pleuritic pain).
• Persistent cough.
• Shortness of breath.
• Fatigue and malaise.
• Weight loss (in chronic cases).

Types of Empyema

Simple (Uncomplicated) Empyema:

• Thin, free-flowing infected fluid.
• Easier to treat with antibiotics and drainage.

Complicated Empyema:

• Fluid thickens, and fibrin deposition occurs, potentially leading to septations or loculations (divided pockets of fluid).
• Requires more aggressive interventions, such as surgery.

Organizing (Chronic) Empyema:

• Fibrosis or scarring develops, encasing the lung and impairing its expansion (pleural peel).
• Surgical intervention (decortication) may be necessary.

Diagnosis

Imaging:

• Chest X-ray: Shows pleural fluid collection.
• Chest CT scan: More detailed; shows locations or thickened pleura.
• Ultrasound: Useful for guiding fluid aspiration.

Thoracentesis:

• A sample of pleural fluid is obtained and analyzed.
• Findings: Purulent fluid, high white cell count, low glucose, low pH, and elevated lactate dehydrogenase (LDH).

Microbiology: Culture and sensitivity testing of the pleural fluid to identify causative organisms.

A. Clinical features:

Empyema is suspected in a patient with pneumonia if:

• Fever and chest pain were prolonged or if they reappear after a period of improvement.
• Worsening of dyspnea, which is suggestive of fluid accumulation and toxemia
• Delayed reabsorption of parapneumonic effusion or if pleural effusion appears after a bronchopleural fistula. (Bronchopleural fistula is characterized by postural cough and a big amount of expectorated pus.). Diagnosis is by methylene blue 1% injected in the pleural cavity and to look for the blue dye in the sputum.
• Cutaneous collection, i.e., empyema necessitans may appear as a skin swelling in any empyema which empties and fills with posture or manipulation and produces an impulse with cough.
• Chronicity is characterized by: normochromic-normocytic anemia and pallor, general malaise, weakness and easy fatigue, recurrent pyrexia with anorexia, and weight loss. Cough and chest pain persist with the appearance of clubbing.
• Later pleural fibrosis with invasion of the underlying lung with fibrous tissue restricts the lung movements. This results in chest deformities such as chest retraction, narrow crowded ribs, scoliosis, dropping of shoulder, and special gait. A persistent draining sinus occurs in specific infections such as tuberculosis and actinomycosis.

B. Thoracocentesis:

The pleural aspirate is foul-smelling in anaerobic infection, brown (chocolate or anchovy sauce) in amoebic hepatic abscess that communicates with the pleural space, and a yellow Sulphur granular appearance (Sulphur granules) from draining sinus in actinomycosis:

Further analysis shows:

1. Identification of organisms by gram-stain, aerobic and anaerobic cultures.
2. Low pH (<7.2).
3. Pleural fluid white cell count > 15,000/ml (neutrophilic).

C. Chest X-ray

This may reveal free or loculated pleural effusions or hydropneumothorax. However, it does not differentiate empyema from sterile pleural effusion

Treatment

1. Thoracocentesis is the initial option for easily aspirated pus.
2. Chest tube drainage with initial antibiotic therapy until culture and sensitivity are available.
3. The use of antibiotics for several weeks is recommended in pyogenic infections (Metronidazole with penicillin for anaerobic infection).
4. Tuberculous empyema responds to anti-tuberculosis treatment.
5. Surgery is indicated in the case of:

• Thick pleural peal requires decortication.
• Thick pleural adhesions and loculations require mechanical adhesiolysis for proper drainage.

1. Antibiotics:

• Broad-spectrum antibiotics are initially, tailored once cultures identify the causative organism.
• Commonly used: Beta-lactams, carbapenems, or combinations like piperacillin-tazobactam.

2. Drainage:

• Chest tube insertion (thoracostomy): To drain the pus.
• Image-guided catheter placement for loculated collections.

3. Fibrinolytic Therapy: Enzymes (e.g., tPA and DNase) to break down fibrin and improve drainage in complicated empyema.

4. Surgery:

• Video-assisted thoracoscopic surgery (VATS): For removing pus, locations, or decortication in severe cases.
• Open thoracotomy: In chronic or refractory empyema.

5. Supportive Care: Pain management, oxygen therapy, and nutritional support.

Prognosis

• With early diagnosis and appropriate treatment, uncomplicated empyema often resolves fully.
• Delayed treatment or chronic empyema may lead to complications like fibrosis, lung restriction, or sepsis, which can be life-threatening.

Prevention

• Timely treatment of pneumonia and other chest infections.
• Proper post-surgical care to prevent infections.
• Vaccinations: Pneumococcal and influenza vaccines can help reduce the risk of pneumonia.

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