Pleural effusion

Question 1

What is a pleural effusion?

Answer 1

A pleural effusion is excess fluid that accumulates in the pleural cavity, the fluid-filled space that surrounds the lungs

Question 2

What are the types of collections which may accumulate in the pleural space?

Answer 2

• Empyema/pyothorax:
  
  • accumulation of pus, due to infection
• Chylothorax:
  
  • accumulation of lymph due to thoracic duct leakage
• Haemothorax:
  
  • accumulation of blood, due to trauma
• Fluid effusion: transudates or exudates

Question 3

How are the causes of a pleural effusion classified?

Answer 3

Transudative effusion causes: (occur due to increased hydrostatic pressure or decreased oncotic pressure)

• Cardiac failure:
  
  • LHF leading to increased hydrostatic pressure
• Liver failure:
  
  • decreased protein production decreasing oncotic pressure
• Renal failure:
  
  • nephrotic syndrome decreasing oncotic pressure
• Peritoneal dialysis

Exudative effusion causes: (occur due to increased capillary permeability)

• Infections
  
  • bacterial pneumonia
  • TB
• Neoplasm
  
  • lung prumary or secondary
  • mesothelioma
• Pulmonary infarction
  
  • PE
• Autoimmune disease
  
  • RA/SLE
• Abdominal disease
  
  • pancreatitis
  • subphrenic abscess

Question 4

Describe the clinical features and examination features of a pleural effusion

(symptoms & signs)

Answer 4

Symptoms:

• May be asymptomatic or present with dysponea and pleuritic pain

Signs (on examination):

• Descreased chest expansion, tracheal deviation away if large
• Stony dull to percussion
• Decreased breath sounds
  
  • Can be bronichial breathing above effusion due to compressed lung
• Reduced vocal resonance
• Mediastinal deviation (in massive effusion)

Question 5

Describe the aetiology and clinical features of an empyema

Answer 5

• An empyema is the presence of pus in the pleural space
• it is caused by bacterial invasion of the pleural space , either spreading into an exudative effusion from adjacent pneumonia, or from direct inoculation (e.g. poor aseptic technique in a chest drain)

Clinical presents:

• As fever plus signs of pleural effusion
  
  • fever, rigors, malaise, pleuritic pain, SOB
• Aspirated fluid is yellow and turbid, with pH <7.2, low glucose, high lactate dehydrogensase

Question 6

What investigations would you do for a unilateral pleural effusion?

What would they show?

Answer 6

Unilateral effusions are more likely to be exudative, with bilateral effusions more likely to be transudative

Investigations:

• CXR:
  
  • Can be detected when >300ml fluid is present, a flat upper border implies there is also a pneumothorax
• USS (to guide aspiration)
• Aspiration:
  
  • Fluid sent to sent microbiology (for MCS)
  • Clinical chemistry (protein, lactate dehydrogenase (LDH), glucose)
  • Cytology
    
    • Exudates have a protein level of >30g/L
    • Transudates have a protein level of <30g/L