Parapneumonic Effusion

Aka: Parapneumonic Effusion, Pleural Empyema, Lung Empyema, Thoracic Empyema

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II. Definitions

  1. Parapneumonic Effusion
    1. Infectious cause of Pleural Effusion (e.g. Pneumonia, Lung Abscess)
  2. Pleural Empyema
    1. Parapneumonic Effusion complicated by pustular collection

III. Causes: Parapneumonic Effusion

  1. Bacterial Pneumonia
  2. Mycobacterium tuberculosis
  3. Fungal Lung Infection
  4. Viral Pneumonia
  5. Parasitic Infection of Lung

IV. Causes: Empyema (pus collection, Bronchopleural Fistula)

  1. See Empyema Pleural Effusion Findings
  2. Infection
    1. Pneumonia (50% of empyema causes)
      1. Community Acquired Empyema
        1. Pneumococcus
        2. Streptococcus species
      2. Health-Care Associated Empyema
        1. Staphylococcus
        2. Enterococcus
        3. Enterobacteriaceae
    2. Abscess
      1. Lung Abscess
      2. Subphrenic abscess
    3. Mycobacterium tuberculosis
    4. Fungal infections
  3. Chest Trauma (especially penetrating chest wounds)
  4. Spontaneous Pneumothorax

V. Differential Diagnosis

  1. See Pleural Effusion Causes
  2. Malignancy
  3. Tuberculosis
  4. Pulmonary Embolism

VI. Symptoms

  1. Persistent Fever
  2. Malaise
  3. Failure to improve despite days of Antibiotics
  4. Pleuritic Chest Pain (distinguish from Pulmonary Embolism)
  5. Findings with chronic Parapneumonic Effusion (distinguish from malignancy, Tuberculosis)
    1. Weight Loss
    2. Night Sweats
    3. Anorexia

VII. Labs

  1. See Pleural Fluid
  2. Pleural cell count with differential
  3. Pleural Gram Stain and culture
    1. Cultures identify organism in 70% of empyema, but only 22% of other complicated Parapneumonic Effusions
    2. Obtain Blood Cultures at same time to increase overall sensitivity
    3. Culture does not identify Tuberculosis

VIII. Types

  1. Minimal Parapneumonic Effusion (does not require Thoracentesis)
    1. Lateral or Anterior Chest XRay with costophrenic angle blunting
    2. Lateral decubitus film with <10 mm fluid height
    3. POCUS or CT with small size (estimated <100 ml)
  2. Simple Parapneumonic Effusion (obtain Thoracentesis, and treated with Antibiotics alone)
    1. Small volume, sterile exudative effusion
    2. No loculated fluid collections
    3. Negative Gram Stain and negative fluid cultures
    4. Pleural Fluid pH > 7.2
    5. Pleural Glucose normal
    6. Pleural Lactate Dehydrogenase (LDH) < 3 fold upper limit of normal
  3. Complicated Parapneumonic Effusion (Thoracentesis, catheter drainage or Chest Tube, thoracoscopy...)
    1. Loculated fluid collections develop (septations, loculations on POCUS)
    2. Large effusion (>50% of hemithorax on Chest XRay)
    3. Pleural Fluid pH < 7.2
    4. Glucose <40 mg/dl
    5. Fluid is no longer sterile (distinguishes from simple Parapneumonic Effusion)
      1. Positive Gram Stain
      2. Positive Pleural Fluid culture
      3. Purulent drainage on initial aspirate
  4. Lung Empyema
    1. Pustular Pleural Fluid distinguishes empyema from complicated Parapneumonic Effusion
    2. Pleural Fluid pH <7.2
    3. Pleural fluid Gram Stain Positive
    4. Pleural FluidGlucose <60

IX. Course

  1. Phase 1: Exudative Parapneumonic Effusion
    1. Visceral pleura is permeable, allowing sterile exudate to form
    2. See Simple Parapneumonic Effusion as above
  2. Phase 2: Fibrinopurulent Parapneumonic Effusion
    1. Fibrin deposition on pleural surface
    2. Loculations form (visible on Lung Ultrasound or CT Chest)
    3. Infected, exudative fluid
    4. Progression to Lung Empyema when pustular fluid accumulates
  3. Phase 3: Organizing Parapneumonic Effusion
    1. Fibrous adhesions interfere with respiratory movement (Restrictive Lung Disease)
    2. Thoracic surgery may be required for decortication of adhesions

X. Management: General

  1. Approach
    1. Antibiotics are indicated in all Parapneumonic Effusion
    2. Complicated Parapneumonic Effusions and Empyemas require drainage
  2. Simple Parapneumonic Effusion
    1. Consistent with Exudative Parapneumonic Effusion
    2. Treated as uncomplicated Parapneumonic Effusion with IV Antibiotics
  3. Complicated Parapneumonic Effusion
    1. Consistent with Fibrinopurulent Parapneumonic Effusion
    2. IV Antibiotics are administered
    3. Catheter drainage required
    4. Intrapleural Fibrinolytics (see adjunctive measures below) are considered for loculation drainage
  4. Empyema
    1. IV Antibiotics
    2. Chest Thoracostomy tube

XI. Management: Chest Tube

  1. Smaller Chest Tube catheters appear as effective as larger catheters
    1. However, catheter should be directed toward dependent regions of fluid collections and empyemas
  2. Tube Thoracostomy Indications in children
    1. Antibiotics alone for small effusions (<25% hemithorax, <1 cm depth on lateral decubitus xray) without Dyspnea
    2. Large effusion (>50% hemithorax)
    3. Respiratory Distress
  3. Tube Thoracostomy indications in adults
    1. Complicated Parapneumonic Effusion
    2. Empyema
  4. Adjunctive measures indicated for thick or loculated effusions
    1. Intrapleural Fibrinolysis (urokinase, Streptokinase, tPA)
    2. Deoxyribonuclease
    3. Video-assisted thoracoscopic surgery (refractory cases)

XII. References

  1. Natesan (2020) Crit Dec Emerg Med 34(7): 29-41
  2. Shen-Wagner (2023) Am Fam Physician 108(5): 464-75 [PubMed]

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