pleural effusion

Write about Pleural Effusion here.

• A Pleural effusion is an excessive accumulation of fluid in the pleural space

• Normally: 

• Fluid is filtered by the parietal pleura (at systemic circulation, which coupled with negative intrapleural pressure and pleural oncotic pressure, leads to fluid filtration)

• Fluid is then absorbed by the visceral pleural (pulmonary circulation, leading to movement of fluid from pleural space to veins and lympahtics)

• This normally balances, but imbalances can occur in:

• Increased capillary pressure (LVF)

• Reduced plasma oncotic pressure (hypoalbuminaemia)

• Increased capillary permeability (disease of pleura)

• Obstruction of lymphatic draining (Ca of lymphatics)

• It can be detected on X-ray when 300 ml or more of fluid is present and clinically when 500 ml or more is present.

• Chest X-ray appearances range from the obliteration of the costophrenic angle to dense homogenous shadows occupying part or all of the hemithorax

• Fluid below the lung (a Subpulmonary effusion) can simulate a raised hemi-diaphragm

• Fluid in the fissures may resemble an intrapulmonary mass

Physical Signs of a Pleural Effusion


By pleural aspiration.  The fluid accumulated may be a Transudate or an Exudate


• Effusions that are transudates can be bilateral

• Protein content < 30 g/l

• Lactic dehydrogenase < 200 IU/l

Causes (increased venous pressure or hypoproteinaemia)

• Heart failure

• Hypoproteinaemia (e.g. nephrotic syndrome)

• Constrictive pericarditis

• Hypothyroidism

• Ovarian Tumours producing Right-sided pleural effusion (Meig's Syndrome)


Protein content > 30 g/l

• Lactic dehydrogenase >200 IU/l

Causes (Infection, Inflammation or Malignancy):


Bacterial pneumonia - can lead to Empyema

• Carcinoma of the bronchus and pulmonary infarction - fluid may be blood-stained



• Connective-tissue disease


Post-myocardial infarction syndrome

• Acute pancreatitis (high amylase content)

• Mesothelioma

Very Rare:


• Yellow-nail syndrome (effusion due to lymphoedema

• Familial Mediterranean fever

Or lymphatic involvement leading to blockage of draining

• Or blockage of SVC -> increased systemic pressure - > effusion.

• Pleural biopsy may be necessary if the diagnosis has not been established from the above aspiration

• Treatment is of the underlying condition

• Pancreatitis may be associated with pleural effusions (probably due to diaphragmatic inflammation)

• These are usually left sided and are characterised by a high amylase content

Ascites may traverse the diaphragm through pleuroperitoneal communications -> Pleural effusion

• Spread of infection or inflammation from a subphrenic abscess or intrahepatic abcess may also cause pleural effusion

Management of malignant pleural effusions:

Those that reaccumulate and are symptomatic can be aspirated to dryness followed by instillation of a sclerosing agent such as tetracycline or bleomycin.  Effusion should be drained slowly since rapid shift of the mediastinum causes severe pain and occasionally shock.  Also can produce re-expansion pulmonary oedema (low risk).

This treatment only produces temporary relief, but surgical pleurodesis is available.


Underlying cause +

• Drainage

• Pleurodesis

• Intrapleural streptokinase (probably no benefit but meant to breakup fibrin deposits and remove loculations)

• Sx