Pulmonary effusion

Condition

• Pulmonary effusion 

Main features

• Normal pleural space has 10-20 ml fluid
• Can be detected on x-ray if > 300 ml fluid in pleural space
• Can be detected clinically if > 500 ml fluid 
• Can be sub pulmonary - simulates a raised diaphragm 
• May be asymptomatic 
• Dyspnoea common with large effusion 
• Chest pain in setting of pleuritis, infection or trauma 
• Signs: mid line trachea, reduce in chest wall movement, stony dull percussion note, reduce in breath sounds, absent or decreased vocal fremitus and no adventitious sounds 
• The fluid may be transudate or exudate (diagnosed by aspirate)
• If blood stained - malignancy, pulmonary infarction , TB

The effusion fluid can be classified into transudate and exudate 

• Transudate (protein content < 30g/L, lactic dehydrogenase < 200 IU/L)
• Causes 
• Heart failure (90% of cases)
• Hypoproteinaemia e.g. nephrotic syndrome
• Liver failure with ascites
• Constrictive pericarditis
• Hypothyroidism 
• Ovarian tumour - right sided effusion (Meigs syndrome)
• Exudate
• Protein content > 30 g/L; lactic dehydrogenase > 200 IU/L
• Causes
• Infection - bacterial pneumonia, pleurisy, empyema, TB, viral 
• Malignancy - bronchial carcinoma, mesothelioma, metastatic 
• Pulmonary infarction 
• Connective tissue diseases (e.g. SLE, RA)
• Acute pancreatitis 
• Lymphoma 
• Sarcoidosis 
• HIV with parasitic pneumonia

Management

• Depends on the extend of the effusion 
• Aspiratin may be required to ascertain diagnosis 

Reference:

John Murtagh's General Practice 5th edition