Pleural effusion + disease

Question 1

What are key features of pleural effusion?

Answer 1

• Pleural effusion is fluid in the pleural space
• Effusions can be divided by their protein content:
  
  • transudates (<30g/L)
  • exudates (>30g/L)
• Blood = haemothorax
• Pus = empyema
• Lymph w/ fat = Chylothorax
• Both blood and air = haemopneumothorax

Question 2

What are risk factors for pleural effusion?

Answer 2

• Congestive heart failure
• Pneumonia
• Malignancy
• Recent CABG
• Renal failure
• Recent MI
• RA, SLE
• Drugs (nitrofurantoin)

Question 3

Pleural effusions may be classified as being either a transudate or exudate according to the protein concentration.

What is the aetiology for transudate (<30) pleural effusions?

Answer 3

• Heart failure
• Hypoalbuminaemia (liver disease, nephrotic syndrome, malabsorption)
• Hypothyroidism
• Meigs’ syndrome

Question 4

What is the aetiology of exudate (>30) pleural effusions?

Answer 4

• Infection → pneumonia, TB, subphrenic abscess
• Connective tissue disease → RA, SLE
• Neoplasia → lung ca, mesothelioma, mets
• Pancreatitis
• Pulmonary embolism
• Dessler’s syndrome
• Yellow nail syndrome

Question 5

What are clinical features of pleural effusions?

Answer 5

• May be asymptomatic
• Pleuritic chest pain
• Cough
• Reduced chest expansion
• Dull percussion note
• Diminished breath sounds
• Signs of associated disease (malignancy, cachexia, clubbing)

Question 6

When should imaging be performed for pleural effusion?

Answer 6

• PA CXR → in all pts
• USS recommended → increases likelihood of successful pleural aspiration + sensitive for detecting pleural fluid septations
• Contrast CT → inreasingly performed to investigate underlyin cause, particularly for exudative effusions

Question 7

How is diagnostic aspiration for pleural effusion carried out?

Answer 7

* Percuss upper border of pleural effusion

• Choose site, 1 or 2 intercostal spaces below
• Infiltrate down to pleura w/ 5-10ml of 1% lidocaine
• Attach 21G needle to 50ml syringe + insert just above upper border of appropriate rib
• Draw off 10-30mL of pleural fluid + send to lab
• Fluid sent for pH, protein, lactate dehydrogenase, cytology + microbiology

If pleural fluid analysis is inconclusive, consider parietal pleural biopsy

Question 8

What is Light’s criteria?

Answer 8

• Develped in 1972, to help distinguish transudate vs exudate
• BTS recommend using criteria for borderline cases
• Exudates = protein > 30 g/L
• Transudates = protein < 30 g/L
• If protein level between 25-35 g/L, Light’s criteria should be applied, an exudate is likely if at least one of following criteria met:
  
  • pleural fluid protein divided by serum protein >0.5
  • pleural fluid LDH divided by serum LDH >0.6
  • pleural fluid LDH more than 2/3rds the upper limits of normal serum LDH

Question 9

What are other characteristics pleural fluid findings?

Answer 9

• Low glucose → rheumatoid arthritis, TB
• Raised amylase → pancreatitis, oesophageal perforation
• Heavy blood staining → mesothelioma, pulm embolism, tuberculosis

Question 10

How do you investigate and manage for pleural infection?

Answer 10

• All pts w/ pleural effusion in association w/ sepsis or pneumonic illness require diagnostic pleural fluid sampling
• If fluid is purulent or turbid/cloudy, a chest tube should be placed to allow drainage
• If fluid is clear but pH < 7.2 in pts with suspected pleural infection → place chest tube

Question 11

How do you manage pleural effusion?

Answer 11

• Treat underlying cause
• Drainage → if symptomatic, drain, repeatedly if necessary, fluid best removed slowly (0.5-1.5L/24hr); it may be aspirated in same way as diagnostic tap, or using an intercostal drain
• Pleurodesis w/ talc may be helpful for recurrent effusions; thorascope mechanical pleurodesis is most effective for malignant effusions; empyemas best drained using chest drain, inserted under USS or CT guidance