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Pleural Effusion



Definition of pleural effusion

  • Accumulation of fluid between the pleural layers


Epidemiology of pleural effusion

  • Estimated prevalence of pleural effusion is 320 cases per 100,000 people in industrialized countries, with a distribution of etiologies related to the prevalence of underlying diseases.


Causes of pleural effusion

  • Can be divided into Transudative or Exudative


Transudative pleural effusion

  • Involve increased hydrostatic pressure or reduced osmotic pressure in the microvascular circulation (commonly caused by organ failures)


    • Failures
      • Left ventricular failure
      • Liver failure (cirrhotic liver disease)
      • Nephrotic syndrome and hypoalbuminaemia
    • Pulmonary
      • Pulmonary embolism (can be transudates or exudates)
      • Atelectasis
      • Malignancy (5% are transudate)
    • Cardiac
      • Constrictive pericarditis
    • Other
      • Hypothyroidism
      • Meig’s syndrome (ovarian tumours producing right-sided effusion)


Exudative pleural effusion

    • Involve an increase in capillary permeability and impaired pleural fluid resorption
    • Infection
      • Parapneumonic
      • TB
      • Empyema
    • Malignancy
    • Rheumatological
      • Rheumatoid arthritis
      • Connective tissue disease (RA, SLE)
    • Pulmonary embolism (can be transudates or exudates)
    • Rare causes
      • Post-MI, pancreatitis, meothelioma, sarcoidosis, asbestosis
      • Drug induced (methotrexate, amiodarone, bromocriptine, phenytoin, nitrofurantoin)
      • Radiotherapy
      • Yellow-nail syndrome, familial Mediterranean fever
      • Lymphangioleiomyomatosis
        • Pneumothoraces and cylothoraces in middle-aged women.
        • Tx: progesterone (but not very good)


Presentations of pleural effusion

  • Clinical examination will usually pick up effusion >500ml
    • SOB
    • Cough
    • Chest pain
    • Reduced chest wall movement
    • Mediastinal deviation away (if large)
    • Stony dullness to percussion
    • Decreased breath sounds
    • Decreased Vocal resonance
    • Bronchial breathing or aegophony (bleating vocal resonance) over top of effusion, due to lung compression



Differential diagnosis of pleural effusion (decreased air entry on auscultation)

    • Consolidation
    • Collapse
    • Pleural thickening


Investigation of pleural effusion

    •  Bloods
      • Including amylase, LDH, TFT
      • RF and autoimmune profile
    • ABG
    • CXR
      • Sensitive to effusion >300ml (some places say 200)
    • USS
      • For assessing pleural effusion
      • For guiding aspiration
    • Aspiration
      • Must be USS guided (BTS Guidelines)
      • Note appearance of fluid
      • Sent for
        • Biochem: protein, LDH, pH, glucose
        • Cytology (at least 20ml sample)
        • MCS and AFB
        • pH
        • Other: Amylase, cholesterol, RF and ANA
    • Further tests
      • CT
        • Ideally scan before fluid removal as can improve images of pleural surfaces.
      • Pleural tissue biopsy for histology and TB culture


Diagnostic criteria for pleural effusion

    • Normal
      • Clear or straw, pH 7.60-7.64, protein <2, WCC<1, LDH<50% plasma, glucose similar to plasma
    • Transudate
      • Protein <30 g/l:  in patients with normal serum protein
    • Exudate
      • Protein >30 g/l: in patients with normal serum protein
      • Light’s criteria
      • More sensitive for diagnosis of exudative effusions and helpful if fluid protein between 25-35 g/l. Positive if one of these is true:
        • Pleural:serum protein ratio; >0.5 = exudate
        • Pleural:serum LDH ratio; >0.6 = exudate
        • Pleural LDH >2/3 the upper limit of normal serum LDH
      • NB. With diuretics, pleural protein and LDH are generally higher.
    • Empyema
      • pH<7.2
      • Glucose usually <3.3
      • Bacteria in it
      • Fluid LDH generally >1000 in empyema
    • LDH>1000
      • Empyema, malignant, rheumatoid, paragonamiasis
    • Bloody
      • Malignancy, TB, PE, trauma
    • Chylothorax
      • Milky white, chylomicrons, cholesterol>4, Triglyceride level > 110mg/dl
    • High amylase
      • Pancreatitis, malignancy, oesophageal rupture
    • Low glucose or low pH
      • Empyema, malignancy, TB, oesophageal rupture, SLE
    • pH>7.3 in malignancy means:

·        More pleural involvement, higher cytology yield, decreased success in pleurodesis, decreased life expectancy


Management of pleural effusion

    • Treat the underlying cause
      •  diuretics, antibiotics, immunosuppressants
    • Aspiration (USS guided)
    • Indications for chest drain:
      • Empyema or parapneumonic effusion with purulent fluid or pH<7.2
      • Malignant effusions which are candidates for pleurodesis
      • Large effusions in acutely unwell patients
    • Pleurodesis
    • Medical or VATs


Complications of pleural effusion

    • Respiratory failure
    • Infection and empyema


Prognosis of pleural effusion

    •  Dependent on underlying cause


Procedure for Thoracocentesis:

For full details on how to perform thoracocentesis, click here. A summary is below:

      • Explain procedure to patient
      • Obtain written consent
        • Complications include pneumothorax, cough, bleeding, empyema, spleen or liver puncture, malignant seeding (particularly in mesothelioma – my need prophylactic radiotherapy to area later)
      • Check clotting (INR <1.5)
      • Must be done under USS Guidance (by a doctor trained in USS – see BTS guidance)
      • Aseptic technique
      • Infiltrate site (skin, intercostals muscle and parietal pleura) with 10ml 1% lidocaine.
      • Aim above the upper border of the appropriate rib to avoid neurovascular bundle that runs below each rib.
      • For Diagnostic Thoracocentesis:
        • Aspirate pleural fluid with a green (21G) needle and 50ml syringe
        • If uncomplicated – no need for CXR post procedure
      • For Therapeutic Thoracocentesis:
        • Hospitals vary as to kit available
        • Verify that insertion site is correct by aspirating fluid with a green (21G) needle
        • Advance a large bore cannula along the same track
        • Remove needle and attach a 3 way tap
        • Aspirate fluid with a 50ml syringe via the 3 way tap and flush the fluid out into container through extension tubing connected to remaining port of 3 way tap.
        • Drain maximum of 1.5l in one go – risk of re-expansion pulmonary oedema
        • Stop aspirating if any resistance felt  or if patient experiences any discomfort or severe coughing
        • CXR post to document extent of improvement and to exclude pneumothorax or trapped lung


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Common Pleural Effusion exam questions for medical students, finals, OSCEs and MRCP PACES


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