🎯 Pathology

• accumulation of fluid in the pleural space

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⚡️ Types

• pleural effusions can be categorised into transudates and exudates based on their protein concentrations

  • transudate (< 30 g/L)

  • exudate (> 30 g/L)

• blood in the pleural space —> haemothorax

• pus in the pleural space —> empyema

• lymph in the pleural space —> chylothorax

• air in the pleural space —> pneumothorax

• blood and air in the pleural space —> haemopneumothorax

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💡 Causes

• transudate

  • mechanism

    • increased hydrostatic pressure in pleural capillaries OR

    • decreased oncotic pressure

  • causes

    • heart failure (most common cause)

    • hypothyroidism

    • hypoalbuminaemia (e.g. nephrotic syndrome, cirrhosis)

    • Meigs’ syndrome (pleural effusion + ascites + ovarian fibroma)

• exudate

  • mechanism

    • increased leakiness of pleural capillaries

  • causes

    • pneumonia (most common cause)

    • malignancy

    • tuberculosis

    • inflammatory conditions (e.g. acute pancreatitis, SLE, rheumatoid arthritis)

    • asbestos

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🩺 Clinical features

• symptoms

  • may be asymptomatic

  • dyspnoea

  • pleuritic chest pain

• signs (on the affected side)

  • reduced chest expansion

  • reduced breath sounds

  • stony dull on percussion

  • reduced vocal resonance

  • tracheal deviation with large effusions

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🕵️‍♂️ Investigations

• chest x-ray (1st line)

  • shows blunting of the costophrenic angle

  • meniscus sign with larger effusions

  • fluid in lung fissures

• ultrasound

  • useful for guiding aspiration

• pleural aspiration

  • sample sent to the lab for analysis of:

    • clinical chemistry (protein, glucose, pH, LDH, amylase)

      • transudate: pH 7.4-7.55

      • exudate: pH 7.3-7.45

      • amylase is high in acute pancreatitis and oesophageal rupture

    • bacteriology (microscopy and culture, TB culture)

    • cytology

  • if protein is between 25-35g/L —> use Light’s criteria to determine if the fluid is transudate or exudate

• pleural biopsy

  • if the sample of the pleural fluid is inconclusive

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❗️Light's criteria

• an effusion is an exudate if any of these criteria are met:

  • pleural protein/serum protein > 0.5

  • pleural LDH/serum LDH > 0.6

  • pleural LDH >2/3 the upper limit of the normal serum LDH

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💆‍♂️ Management​

• address the underlying cause (e.g. antibiotics for pneumonia)

• chest drain

• recurrent —> pleurodesis

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😢 Complications

• re-expansion pulmonary oedema may occur if >1000-1500 ml of fluid is drained in a single attempt