13: Pleural Diseases

Question 1

Pleural space

Answer 1

• Potential space with minimal fluid content
• Many disease states represent an abnormal increase in air/fluid/material in the pleural space and/or a loss of pleural integrity

Question 2

Pleural fluid

Answer 2

• Normal volume: 4-15mL
• Normal RBC count: 700x10³ cells/mL
• Normal WBC count: 1,700x10³cells/mL
  
  • 23% lymphocytes
  • 75% macrophages
  • 0% neutrophils
• Sources:
  
  • In health: pleural capillaries
  • In disease: lung interstitium, lymphatics, peritoneal space

Question 3

Mechanisms for pleural disease

Answer 3

1. Loss of pleural integrity
   
   • Pneumothorax
   • Pneumomediastinum
   • SubQ emphysema
2. Abnormality of pleural fluid production
   
   • Heart, renal, liver failure (transudates)
   • Infection, malignancy, inflammation, misc (exudates)
3. Additions to the pleural space

Question 4

Types of pleural effusion fluids

Answer 4

• **Transudate: **​caused by systemic factors that alter te balance of formation and absorption of pleural fluid
  
  • cirrhosis
  • heart failure
• **Exudate: **caused by alterations in local factors that influence the formation and absorption of pleural fluid
  
  • infection
  • inflammation
  • malignancy
• Light’s Criteria: exudative if:
  
  • (protein fluid / protein serum) > 0.5
  • (LDH fluid / LDH serum) > 0.6 or 2/3 upper limit of normal for serum LDH

Question 5

Parapneumonic effusions

Answer 5

• Exudative effusion due to pneumonia
• Seen with 50% of pneumonias
• 3 types:
  
  • Simple/uncomplicated: inflammatory process extends to pleura, causing mediator-induced change in permeability of local tissues and fluid accumulation; non-infected
  • Complicated: bacterial invasion from parenchyma into plueral space; requires drainage to prevent “trapped lung”
  • Empyema: frank pus in pleural space; requires drainage
• Dx complicated/empyema: frank pus, positive gram stain or culture, pH < 7.20, glucose < 20mg/dL

Question 6

Treatment of pleural space

Answer 6

• Thoracentesis
• Chest tube drainage
• Direct pleural examination
  
  • Blind pleural biopsy
  • Pleuroscopy
  • Video-assisted thoracic surgery (VATS)
  • Open thoracotomy

Question 7

Chylothorax

Answer 7

• Rare
• Milky pleural fluid
  
  • Lymphocyte rich
  • Lipid rich
  • Exudative (rarely transudative)
  • Gs > 110 (diet dependent)
• Causes:
  
  • Trauma (50%)
  • Malignancy, lymphatic disorder (lymphoma)
  • Idiopathic
  • Rare: sneezing, vomiting, seat belt use, goiter
• Tx: chest tube, pleurodesis (adhere 2 pleura), surgical repair or ligation
  
  • 50% of traumatic causes resolve w/o surgical intervention

Question 8

Urinothorax

Answer 8

• Very rare
• Usually unilateral
• Transudative (occasionally exudative)
• Etiology
  
  • Benign obstructive uropathy
  • Malignant obstructive uropathy
  • Renal biopsy
  • Lithotripsy
  • Nephrostomy
  • Surgery/trauma
  • Renal transplant
• Tx: relieve obstruction

Question 9

Meig’s Syndrome

Answer 9

• Very, very rare
• Usually right-sided
• Mechanism unknown, possibly transdiaphragmatic lymphatic leak
• Can occur with fibroma, thecoma, cystadenoma, or granulosa cell tumor
• Can mimic ovarian cancer with elevated cancer antigen-125 levels
• Effusion resolves with resection of tumor

Question 10

Yellow Nail Syndrome

Answer 10

• Extremely rare
• At least two of the following:
  
  • Pleural effusion
  • Yellow nails
  • Lymphedema
• Can have bronchiectasis and recurrent upper/lower airway infx
• Effusions
  
  • Usually bilateral
  • Exudative by protein criteria
  • 1/3 are chylous
• Tx: pleurodesis, thoracic duct ligation