Background
Definition
- Pleural effusion secondary to bacterial pneumonia
- Complicated (i.e. infected and needs drainage) if:
- Frankly purulent drainage
- Positive Gram stain or culture
- Pleural fluid pH <7.2
- Possibly also:
- >50% of the hemithorax
- Loculated
- LDH > 1000
- WBC > 25
- Glucose < 3.4
Stages
- Exudative (Stage 1): not infected but exudative, generally echo-free on pleural ultrasound, free flowing, and with minimal to no enhancement on CT scan
- Fibropurulent (Stage 2): generally fibropurulent, likely infected, usually loculated with echogenic fluid, debris, and septations, and associated with pleural enhancement
- Organizing (Stage 3): organized empyema with significantly thickened, scarred pleural membranes
Risk Classification
| Risk | Anatomy | Microbiology | Chemistry |
|---|---|---|---|
| Very low | free-flowing effusion <1cm on lateral decubitus | AND Gram stain and culture unknown | AND pH unknown |
| Low | free-flowing effusion 1cm ot 1/2 hemithorax | AND Gram stain and culture negative | AND pH ≥7.2 |
| Moderate | free-flowing effusion ≥1/2 hemithorax, or loculated effusion, or thickened parietal pleura | OR Gram stain or culture positive | OR pH <7.2 |
| High | pus |
Clinical Manifestations
- Fever, cough, pleuritic chest pain
Empyema Necessitans
- Chronic empyema that drains through chest wall
- Caused by tuberculosis or actinomycosis
Differential Diagnosis
- Pleural effusion from other causes
Investigations
- Chest x-ray with PA, lateral, and lateral decubitus
- Check to free-flowing or loculated effusion
- If base of meniscus on the lateral is > 5cm or on the lateral decubitus is > 1cm, need to perform diagnostic thoracentesis
- Diagnostic thoracentesis, sent for pH, protein, cell count and differential, and Gram stain and culture
Management
- Can add metronidazole for anaerobic coverage (unless confirmed pneumococcal infection)
- Drainage, if complicated (see Definition, above)
- Ideally chest tube
- If not chest tube, then pigtail catheter, but this often needs upsizing to chest tube
- Can add intrathoracic tPA and DNAse, but unclear benefit
Further Reading
- Light RW. Parapneumonic effusions and empyema. Proc Am Thorac Soc 2005;3:75-80.
- Colice GL et al. Medical and surgical treatment of parapneumonic effusions: an evidence-based guideline. Chest 2000;118(4):1158-71.
- Davies HE et al. Management of pleural infection in adults: British Thoracic Society Pleural Disease Guideline 2010. Thorax 2010;65 Suppl 2:ii41-53.
