Pleural effusion

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Background

  • Exudative
    • Active fluid secretion or leakage with high protein content
  • Transudative
    • Imbalance between hydrostatic (e.g. CHF) and oncotic (e.g. nephrotic syndrome)
    • Fluid has low protein content

Evaluation

Detection

  • CXR
    • Earliest sign is blunting of costophrenic angle
    • PA view requires 200-250cc of fluid; Lateral requires 50-75cc of fluid
    • Supine view may only show a generalized hazy appearance of affected hemithorax
    • Subpulmonic effusion
      • Fluid collects in isolation between lung base and diaphragm
      • May not cause blunting of costophrnic angle or meniscus appearance
      • Suspect if "hemidiaphragm" (actually fluid) is elevated and flattened
      • Lateral decubitus with suspected side down will show free-flowing pleural fluid
  • CT
  • US

Exudative versus Transudative (Light's Criteria)

  • If one of the following is present the fluid is virtually always an exudate
  • If none is present the fluid is virtually always a transudate
    • Pleural fluid/serum protein ratio >0.5
    • Pleural fluid/serum LDH ratio >0.6
    • Pleural fluid LDH > two thirds of upper limit for serum LDH

Exudative Work-up

  • Gram stain and culture (place 10cc into blood culture bottle at the bedside)
  • Cell count
    • RBC >100K: trauma, malignancy, pneumonia, or pulmonary infarction
    • Neutrophil predominance (>50%): parapneumonic, pulmonary embolism, pancreatitis
    • Lymphocytic predominance (>50%): malignancy, TB, PE, viral pleuritis
  • Glucose
    • Low glucose (<60) seen in parapneumonic, empyema, malignant, TB, and RA
  • ABG (pH)
    • May be left at room temperature for up to 1hr with out affecting results
    • Normal pleural fluid pH = 7.64;
    • In parapneumonic effusions, <7.10 predicts development of empyema or persistence and indicates need for thoracostomy tube drainage
  • Amylase: >100 in pleural effusions due to pancreatitis or esophageal rupture
  • TB (adenosine deaminase)
  • India ink
  • Cytology (requires 50cc)

Work-Up

Thoracentesis

Differential Diagnosis

Pleural effusion.png

Common

  • Transudative
  • Exudative
    • Cancer
    • pneumonia (parapneumonic effusion)
      • Occurs in 40% of patients hospitalized with pneumonia
    • PE
      • Occurs in 30% of patients with PE

Less Common

  • Transudative
    • Nephrotic Syndrome
    • Cirrhosis
      • Both via hypoalbuminemia and transdiaphragmatic leakage of ascites
    • PE
  • Exudative
    • Viral, fungal, or parasitic infection
    • SLE, RA
    • Uremia
    • Pancreatitis
    • Amiodarone

Non-infectious Effusions

Management

  • Dyspnea at rest
    • Therapeutic thoracentesis with max drainage 1-1.5L to avoid reexpansion pulmonary edema
  • Patient positioning (lateral decubitus) for unilateral pleural effusions
    • Most of the time, "Good lung to Ground" to improve V/Q mismatch
    • Exceptions in which "bad" lung should be "down":
      • Massive hemoptysis
      • Severe/large pleural effusions
      • Large pulmonary abscesses
  • Empyema
    • Drain with large-bore thoracostomy tube
  • Parapneumonic Effusion
    • Consider thoracostomy tube drainage if:
      • Comorbid disease
      • Failure to respond to antibiotic treatment
      • Anaerobic organisms
      • Pleural fluid pH <7.10
      • Effusion involving >50% of thorax or air-fluid level on CXR
      • Loculated effusion
  • CHF
    • Diuretic therapy resolves >75% of effusions within 2-3d

See Also

Thoracentesis


External Links

References