Pleural Effusion

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quick reference

Light’s Criteria MD Calc

Light’s Criteria

Effusion is exudative if one of the following are met:

• Pleural fluid-to-serum protein ratio > 0.5
• Pleural fluid-to-serum LDH ratio > 0.6
• Pleural fluid LDH > 0.67 (ie, two-thirds) the upper limits of the laboratory’s normal serum LDH

Remove <1500c or risk of reexpansion pulmonary edema

Labs

• Always:
  • Serum LDH
  • Pleural Fluid LDH
  • Cell count and differential
  • Glucose
  • Gram stain & culture
• Sometimes:
  • Albumin
    • HF/Cirrhosis etiology
  • AFB (TB)
  • ADA (TB)
  • pH - if malignant effusion, more likely to shift towards anaerobic glycolysis with corresponding increase In lactate (Warburg effect)
    • <7.32 = poor prognosis
    • review
  • Additional microbiological studies:
    • Fungal stain & culture.
    • Acid-fast bacilli stain and culture; adenosine deaminase (ADA).
  • Additional evaluation for malignancy:
    • Cytology.
    • Flow cytometry if concern for lymphoma.
  • Additional labs for milky fluid:
    • Triglyceride level.
    • Cholesterol level.
  • Labs that evaluate for anomalous connections:
    • Amylase (positive in pancreatic disease, esophageal rupture, malignancy).
    • Creatinine (may reveal urinothorax).
    • Bilirubin (obtain if pleural fluid is green or black; pleural fluid bilirubin that is higher than serum bilirubin indicates bilothorax).
    • Beta-2 transferrin (if suspect duropleural fistula).

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pathophysiology

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epidemiology / etiology

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clinical features

Symptoms:

• SOB/DOE
• Pleuritic pain
• Back Pain

PE:

• Tachycardia/Tachypnea
• Hypoxia
• Absent/dull lung sounds
• dullness to percussion

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diagnosis

Imaging
-XRAY

• air-fluid level

-CT

• air-fluid level
• Compressive atelectasis
• Concerning:
  • Rim enhancement
  • loculations
  • Heterogeneous intensities or higher HU
  • “Defying-gravity”

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treatment

Thoracentesis:

• diagnostic and therapeutic

Recurrent effusions:

• Pleurodesis
  • Mechanical / chemical

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