13- PLEURAL EFFUSION

Cards (17)

  • Light's criteria
    • Pleural fluid is an exudate if one or more of these criteria are met:
    • 1. Pleural fluid protein > 0.5 serum protein
    • 2. Pleural fluid LDH> 0.6 serum LDH
    • 3. Pleural fluid LDH> 2/3 upper normal serum limit
  • Rare effusions
    • blood (hemothorax)
    • pus (empyema)
    • lymph (chylothorax) from the thoracic duct (trauma or carcinoma)
  • Exudate
    Due to damaged pleura resulting in loss of tissue fluid and protein or impaired lymphatic drainage
  • Transudate
    Due to disruption of hydrostatic forces in chest or fluid from peritoneum
  • Exudate characteristics
    • Pale yellow and cloudy
  • Transudate characteristics
    • Clear, pale yellow, watery
  • Common causes of exudates
    • Pulmonary TB
    • Pneumonia
    • Bronchial carcinoma
    • Pulmonary infarction
    • Collagen disease (SLE, RA)
    • Lymphoma
    • Sarcoidosis
    • Pulmonary embolism (may cause both)
  • Common causes of transudates
    • Congestive heart failure
    • Cirrhosis of the Liver
    • Nephrotic syndrome
    • Hypoproteinemia
    • Meigs syndrome (Right pleural effusion, Ascites, Ovarian fibroma)
    • Atelectasis
    • Pulmonary embolism (may cause both)
  • Diagnosis of pleural effusion
    1. Initial test: Plain CXR
    2. Pleural fluid aspiration (thoracentesis)
    3. Contrast-enhanced CT
    4. Pleural biopsy
  • Plain CXR
    • Detects effusion when >300 ml
    • Homogenous dense radio-opacity occupying the "..." lung zones, obliterating the costophrenic angle, with a meniscus sign
    • Lateral decubitus view used to assess loculation and more reliable for small effusions
  • Pleural fluid aspiration (thoracentesis)
    • Diagnostic and therapeutic
    • Done unless the clinical picture clearly suggests a transudate
    • If small effusion/unsuccessful blind aspiration à US-guided aspiration
    • Note the color, send for protein, LDH, glucose, pH (<7.2 in empyema), cytology, cell count, gram stain and culture, acid-fast bacilli stain and culture, amylase if suspected pancreatitis-associated effusion, and lipid profile if suspected chylothorax (high TG)
  • Contrast-enhanced CT
    • Done if the previous test doesn't provide a diagnosis
    • Most useful when pleural fluid is present to enhance the contrast between pleural abnormality and fluid
  • Pleural biopsy
    • Definitive diagnosis
    • Send for TB smear and culture and histology
  • Differentiate between hemithorax and hemorrhagic pleural effusion
    • Pleural:serum Hct ≥ 50 à hemothorax
    • Pleural:serum Hct < 50 à hemorrhagic pleural effusion
  • Treatment of transudate
    1. Treat the underlying cause
    2. Large effusions (ex. 1L) need large volume thoracocentesis
  • Treatment of exudate
    1. Parapneumonic effusion: antibiotics ±chest tube drainage (in most cases antibiotics alone are enough)
    2. Empyema: Antibiotics + chest tube drainage
    3. ± pleurodhesis in empyema/malignancy
    4. ± surgical lysis of adhesions in empyema
    5. ± intrapleural injection of thrombolytic agents (streptokinase or urokinase)
  • Indications for tube thoracotomy (chest tube)
    • Complicated/infected effusion (+ve gram stain and culture)
    • Loculated effusion
    • Empyema (pH<7.2)
    • >50% hemithorax