Pleural Effusion

Question 1

Comms: Pleural Effusion

Answer 1

• Lungs are covered by a thin sheet like material called the pleura
• There is normally a small amount of fluid between this sheet and the lung
• Purpose of this fluid is to help lubricate the lungs so they can expand easily
• Pleural effusion is where the amount of fluid is greater than normal usually due to disease resulting in symptoms you are experiencing

Question 2

Distinguish transudate from exudate in pathological terms?

Answer 2

TRANSUDATE

• Increased hydrostatic pressure OR decreased colloid pressure
• Results in fluid leakage
• Fluid lacks protein

EXUDATE

• Inflammation increase endothelial spaces
• Both fluid and protein leak into spaces
• Results in fluid with high protein content

Question 3

Distinguish Transudate from Exudate in terms of protein content?

Answer 3

Transudate = <30g/L
Exudate = >30g/L

IF Protein content between 25-35g/L apply LIGHT’S CRITERIA:

• Exudate if:
  1) pleural fluid protein / serum fluid protein >0.5
  2) pleural fluid lactate / serum LDH >0.6
  3) pleural fluid lactate is > 2/3rd upper limit serum lactate

Question 4

CAUSES: Transudate

Answer 4

• Liver cirrhosis
• Congestive Heart Failure
• Hypoalbuminaemia
• Peritoneal dialysis

(Less common)

• Pulmonary embolism
• Mitral stenosis
• Nephrotic syndrome

(Rare)
-Meig’s syndrome

Question 5

CAUSES: Exudates

Answer 5

• Pneumonia
• Malignancy - breast/lung

(Less common)

• Autoimmune: SLE, RA
• Asbestos
• Pulmonary infarction
• TB

Drugs

• Amiodarone
• Methotrexate
• Nitrofurantoin

Question 6

Define empyema?

Answer 6

Grossly prudent exudative pleural effusion

Question 7

CLINICAL FEATURES: Pleural Effusion

Answer 7

Symptoms

• SOB
• Pleuritic chest pain - worse on inspiration/movement/cough
• Cough (only productive w/ pneumonia)

Signs

• Decreased breath sounds
• Decreased/absent tactile fremitus
• Dull percussion

Question 8

INVESTIGATIONS: Pleural Effusion

Answer 8

Cultures
-Pleural aspirate (protein content, microscopy, gram stain, culture, cytology, lactate content, pH, acid/alcohol fast bacilli culture, amylase, triglycerides)

Imaging

• CXR: blunting costophrenic angles + basal opacity
• Bronchoscopy and high-resolution CT (underlying cause)

Question 9

What do the various components of the pleural aspirates tell you?

Answer 9

pH

• Normal = 7.6
• <7.2 = infected effusion = drainage

Glucose
-Low = empyema, RA, SLE, TB, malignancy

Amylase
-High = acute pancreatitis, oesophageal rupture, malignancy

Cytology
-Positive in ~60% malignancy

Question 10

MANAGEMENT: Pleural Effusion

Answer 10

TREAT UNDERLYING CAUSE

• Respiratory compromise = Pleurocentesis
• If fluid re-accumulates a chest drain should be considered