Intern Report 2/16 – Pleural Effusions

Teaching Points

  • Parapneumonic effusions are effusions associated with pneumonia, which can occur in about 20-25%
  • If <10mm on lateral film and/or decreasing with antibiotic treatment, may continue to monitor and just treat with antibiotics.
  • Lights Criteria  – differentiates transudative and exudative fluid.
    • Criteria
      • Pleural TP/Serum TP >0.5
      • Pleural LD/Serum LD >0.6
      • Pleural LD > 2/3 ULN plasma LD
    • Need at least one positive result to categorize pleural fluid as exudative.
      • Setup of Light’s criteria leads to increased sensitivity and decreased specificity.
      • Purpose is due to the fact that you don’t want to miss a process causing an exudative fluid so you want your rate of false negatives to be low. Hence an increased sensitivity.
  • Cell count
    • Predominant neutrophlic – bacterial
    • Predominant lymphocytic – think TB or malignancy
    • Predominant eosinophil – think irritation due to blood, air, etc
  • Complicated parapneumonic effusion associated with worse outcomes, necessitates need for drainage.
    • pH<7.2 (normal pleural fluid pH 7.6)
    • Pleural glucose <60

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