Pneumonia Complications: Empyema
Oren Kupfer, MD, and Paul C. Stillwell, MD, FAAP
Introduction/Etiology/Epidemiology
•An empyema is a collection of pus in an enclosed part of the body that is normally sterile, which may occur in the pleural space as a complication of pneumonia. Empyemas are by definition exudative pleural effusions.
•Although several different infections can be responsible, the most common are Streptococcus pneumoniae and Staphylococcus aureus (both methicillin sensitive and methicillin resistant) (Box 63-1).
•The incidence of complex pneumonia and empyema has increased since the 1990s, though the exact cause is unknown.
•An estimated 0.6%–2.0% of pediatric patients hospitalized for pneumonia will have an empyema.
| Bacteria | Viruses and Atypical Bacteria |
| Streptococcus pneumoniae | Adenovirus |
| Staphylococcus aureus | Parainfluenza |
| Haemophilus influenzae type b | Influenza |
| Streptococcus pyogenes | Mycoplasma pneumoniae |
| Bacteroides species | Fungi |
| Peptostreptococcus species | Coccidioides immitis |
| Peptococcus species | Parasites |
| Fusobacterium species | Paragonimus species |
| Actinomyces species | Cysticercus species |
| Tuberculosis | Entamoeba histolytica |
| Mycobacterium tuberculosis |
•Most children with an empyema caused by Streptococcus or Staphylococcus are acutely ill with high fever, ill appearance, chest pain, and respiratory distress.
•If the patient does not appear seriously ill, the etiologic origin is likely a less virulent organism (see Box 63-1).
•At examination, the breath sounds over the empyema will be decreased or absent, and there will be a dull percussion note.
•Adjacent to the empyema, crackles may be heard, reflecting the portion of the lung affected by the underlying pneumonia.
Diagnostic Considerations
•Chest radiographic findings have the characteristic appearance of pneumonia, with a pleural effusion blunting the costophrenic angle and a meniscus sign (Figure 63-1).
Figure 63-1. Pleural effusion. Frontal chest radiograph shows a left lower-lobe pneumonia with blunting of the costophrenic angle (meniscus sign), indicating pleural fluid, which was proven to be caused by an empyema.
• Clinicians should ask about exposure to persons with tuberculosis and consider administering tuberculin skin test or interferon-based test for high-risk populations, such as immigrants (see Chapter 58, Tuberculosis).
•Ultrasonography (US) can be used to confirm an effusion and identify loculations and septations in the effusion (see Figure 63-2).
•Chest computed tomography (CT) can be used to clarify the degree of effusion and help differentiate parenchymal disease from pleural involvement. (see Figure 62-3 in Chapter 62, Complications of Pneumonia: Pleural Effusions).
•Pleural fluid should be sampled by means of either thoracentesis, when the chest tube is placed, or at the time of video-assisted thoracoscopic surgery (VATS).
•As a parapneumonic effusion progresses from the initial collection of noninfected fluid to the exudative stage, the fluid characteristics change. As the effusion progresses to the fibrinopurulent stage, there is an increase in the cell counts, and septations become evident at US or chest CT. The infection may extend into the pleural space as evidenced by
—Gross pus at inspection of the fluid
—White blood cell count >12,000/mm3 (12 × 109/L)
—Positive Gram stain finding or culture result
Treatment
•All treatment options include intravenous (IV) antibiotic therapy directed against the infecting organism.
•If no organism is identified, antibiotic therapy is usually directed at Streptococcus or Staphylococcus.
Figure 63-2. Empyema in a 3-year-old girl with fever and lower-lobe pneumonia. A. Frontal chest radiograph shows right lower-lobe opacity. B. Longitudinal ultrasonographic image demonstrates a hypoechoic pleural collection (arrow) surrounding the lower lobe (star).
•Fibrinolytics, such as tissue plasminogen activator or urokinase, may be injected into the pleural space via the chest tube to resolve loculations in the pleural space.
•The use of fibrinolytics and VATS has similar outcomes in terms of hospital length of stay and duration of symptoms.
•The duration of IV antibiotic therapy, the transition to oral antibiotics, and the duration of total antibiotic therapy have not been clearly established.
•IV antibiotics are commonly administered until clinical improvement occurs; the total antibiotic duration is commonly 3–4 weeks or longer.
•A peripherally inserted central catheter (PICC) can facilitate administration of long-term IV antibiotics inside and outside of the hospital setting. Studies in which IV and oral antibiotics were compared at the time of discharge for children with empyemas and complicated pneumonia have shown similar clinical outcomes. The benefits versus risks of a PICC
line as opposed to using oral antibiotics should be considered on an individual basis.
Prognosis
•Despite the extensive radiographic involvement of the lung parenchyma and pleura, the prognosis is excellent for a return to normal, both radiographically and functionally.
•Even with clearing of the infection, there may be prolonged fevers because the inflammation in the pleural space takes some time to resolve.
•The radiographic findings may not return to normal for several months.
•A trapped lung is an uncommon occurrence in children.
When to Refer
•An empyema represents a complex pneumonia with pleural infection that often requires inpatient care with multidisciplinary input from surgery and pulmonology, infectious disease, and perhaps intensive care. Referral should be considered at the earliest suspicion that an empyema is present.
Resources for Families
•Pneumococcal Disease: Clinical Features (U.S. Centers for Disease Control and Prevention). www.cdc.gov/pneumococcal/clinicians/clinical-features.html
•Empyema (Healthline). www.healthline.com/health/empyema#Overview1
•A pleural effusion or empyema should be suspected if treatment for pneumonia fails to produce clinical improvement or if the patient worsens despite treatment.
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