Pleural space pathology: Pleural Effusion Flashcards
Definition
Abnormal excess fluid accumulation in the pleural space between the visceral and parental layers
Diseases which increase the filtration rate or decrease the absorption rate will result in the accumulation of pleural fluid
Physiology
Normal pleural fluid is filtered from the pulmonary microvasculature and absorbed by the lung lymphatics.
Types of fluid
Transudative effusion (protein < 30g/L): caused by increased hydrostatic pressure or low oncotic pressure.
Exudative effusion (protein > 30g/L): caused by inflammation, infection and malignancy.
Causes of transudative fluid
- Heart failure (MC) : increased microvascular pressure → pulmonary oedema → increased fluid being filtered into the low-pressure pleural space
- Cirrhosis: liver failure → hypoalbuminaemia → low plasma oncotic pressure → increased filtration of pleural fluid
- NephrOtic syndrome
- Hypothyroidism
- Peritoneal dialysis
Causes of exudative fluid
Malignancy (MC) : tumour infiltration of pleural capillaries and cytokines increase capillary permeability → increased leakage of fluid into the pleural space
Pneumonia (MC) : acute lung injury → increased vascular permeability → movement of high protein lung interstitial fluid into the pleural space
Pulmonary embolism
Pancreatitis
Autoimmune and connective tissue disorders
Dressler’s syndrome
What colour is transudative fluid
Transparent
What colour is exudative fluid
Cloudy
Signs
- Reduced chest expansion and breath sounds on the affected side
- Decreased tactile or vocal fremitus
- Dullness to percussion: the most accurate positive finding, classically ‘stony dull’
- Pleural friction rub + bronchial breathing
Symptoms
SOB/ Dyspnoea
Cough
Pleuritic chest pain: usually exudative
Symptoms of underlying cause e.g.
- Peripheral oedema (HF)
- Ascites (liver cirrhosis)
- Productive cough and fever (pneumonia)
DDx
Pneumothorax
Diagnosis
FIRST LINE + GOLD STANDARD = CXR
- Decreased costophrenic angles (BLUNTING)
- Excess fluid appears WHITE +/- tracheal deviation
Thoracentesis = sample pleural fluid
- pH, lactate, WCC, microscopy
- transudate or exudate
Light’s criteria
If the protein level is 25-35 g/L, Light’s criteria should be applied.
Validated set of pleural fluid lab test findings used to distinguish between transudate and exudate effusions for borderline presentations.
Light’s criteria state that an exudate is likely if one or more of the following criteria are met:
- Pleural fluid protein divided by serum protein is > 0.5
- Pleural fluid LDH divided by serum LDH is > 0.6
- Pleural fluid LDH > 2/3 the upper limit of normal serum LDH
Treatment
Chest drainage (thoracentesis)
Pleurodesis: scarring of the pleural space by slurry injection/talc
Treat underlying cause:
- loop diuretics for CHF
Complications
Empyema
Pneumothorax