25. Pleural diseases - Cox

• Pleural Effusion - abnormal accumulation of fluid in the pleural cavity
• Pneumothorax - pleural air
• Pleural fluid maintained via balance of

  • hydrostatic pressure
  • oncotic pressure
  • lymphatic drainage

  Disturbance will cause pleural effusion
• Fluid balance disturbance

  • increase hydrostatic pressure
  • decrease oncotic pressure
  • obstruction of lymphatic drainage
  • increase vascular permeability
• Pleural effusion - separating visceral and parietal pleura can cause?

  passive atelectasis
• Expanding pleural effusion can cause?

  mass effect leading to compression atelectasis - will flatten diaphragm and impair respiration
• The most common symptom associated with pleural effusion is?


  dyspnea and pleural chest pain due to pleural irritation
• Transudates - ultrafiltrates of plasma

  • increase hydrostatic pressure
  • decrease oncotic pressure
• Transudates seen in renal failure and cirrhosis
• Exudates - protein and cell rich fluid

  • increase vascular permeability
  • due to inflammation or malignancy
• Transudate specific gravity is less than 1.016
• transudate have low protein content
• exudate - specific gravity is more than 1.016
• What is used for determining exudate?

  light's criteria - satisfying 1 criteria = exudate
• Light's criteria for exudate

  1. Effusion fluid protein > 0.5
  2. effusion fluid LDH > 0.6
  3. LDH must be 1/3 > upper limit of normal range
  4. LDH > 133
• Hemothorax - blood within chest

  • causing ipsilateral lung compression
• Chylous pleural effusions - pleural space is filled with chylous fluid - usually exudate
• Uncomplicated parapneumonic effusion - sterile and resolves with resolution of pneumonia
• Complicated parapneumonic effusion

  • pleural bacterial invasion + neutrophil
  • increase LDH levels
  • decrease glucose
• Simple Pneumothorax - presence of air in pleural cavity
• tension pneumothorax pathogenesis

  • pleural tear allows air into pleural cavity but can't escape
  • increase pleural cavity pressure leading to compression atelectasis
• Mesothelioma - associated with asbestos exposure
• Transudate - the membrane is intact, just fluid out
• Mesothelioma - cause by crocidolite arsenic