The appearance of the meniscus is a visual illusion due to the shape of the chest thorax with more fluid seen laterally. There is no real meniscus. Diagnostic tap with 20 ml syringe with a 21 G needle to obtain 20 mL of fluid. This should be sent to the laboratory for Protein/LDH, Cell count, Culture, including TB, Large volume really needed to be spun down for cytology for malignant cells.
- Collection of fluid within the pleural space impairs lung function
- May suggest underlying lung or pleural pathology
- Pleural effusion: fluid in pleural space
- Pneumothorax: air in pleural space
- Empyema: pus in pleural space
- Haemothorax: Blood in pleural space
- Chylothorax: Chyle in pleural space
- Many mechanisms - inflammation. malignancy, altered local permeability and altered osmotic forces.
- Classically divided by protein levels into high protein exudates and low protein transudates which helps narrow down cause
Clinical (needs > 500 mls to be clinically detectable)
- Increasing breathlessness
- Pleuritic type chest pain
- Reduced chest wall movement
- Stony dull percussion note
- Deviation of the trachea and mediastinum away with a massive effusion
- Decreased vocal resonance
- Absent breath sounds
- Bronchial breath sounds at top of effusion
Light's criteria: Fluid is exudate if one of the following Light criteria is present
- Effusion protein/serum protein ratio greater than 0.5
- Effusion LDH/serum LDH ratio greater than 0.6
- Effusion LDH level greater than two-thirds the upper limit of the laboratory's reference range of serum LDH
- Cancer: fluid is serous exudate +/- blood. Malignant cells may be seen when spun down. Positive pleural biopsy (40%).
- Cardiac failure: Serous, straw-coloured transudate. May respond to fluid restriction and diuretics. The BNP is elevated.
- Tuberculosis: Clear amber-coloured fluid with Lymphocytes (occasionally
polymorphs) Exudate. Positive tuberculin test. Mycobacterium tuberculosis isolated from pleural
fluid in only 1/5th and pleural biopsy more useful. Raised adenosine deaminase
- Pulmonary infarction: clear or blood-stained. Exudate or transudate. PE and infarct are seen on CTPA
- Rheumatoid disease: serous often turbid with a high number of Lymphocytes. Positive Rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies. Cholesterol is seen in chronic effusion. Classically low glucose.
- Systemic lupus erythematosus: serous lymphocytic. Positive Antinuclear factor or anti-DNA positive.
- Acute pancreatitis: clear serous or bloody fluid. Elevated amylase in pleural fluid
- Chylothorax: Milky fluid. Obstruction of the thoracic duct. Fluid full of Chylomicrons
Causes using Light's criteria
- Exudates: Increased protein or LDH
- Abdominal infections, abscess, ascites,
- Meigs syndrome, pancreatitis
- Churg-Strauss disease, lupus, rheumatoid arthritis, Wegener granulomatosis
- Hypothyroidism, ovarian hyperstimulation
- Drug-induced, oesophageal perforation, a feeding tube in lung
- Lung abscess, bacterial pneumonia, fungal disease, parasites, tuberculosis
- Acute respiratory distress syndrome (ARDS)
- Asbestosis, pancreatitis, radiation, sarcoidosis, uremia
- Chylothorax, malignancy, lymphangiectasia
- Carcinoma, lymphoma, leukemia, mesothelioma, paraproteinemia
- Atelectasis, Cerebrospinal fluid (CSF) leak into pleural space
- Thoracic spine injury, ventriculoperitoneal (VP) shunt dysfunction
- Heart failure, Liver failure, Nephrotic syndrome and Hypoalbuminemia
- Iatrogenic: Misplaced catheter into lung
- Peritoneal dialysis
- Urinothorax: Due to obstructive uropathy
- Indicated when there is a local exudative cause to ease breathlessness. Avoid in heart failure and low protein states and diuretics were given. A large volume can be useful to send for cytology.
- Ideally drain the effusion with an intercostal drain usually placed low over the diaphragm. General advice now to use ultrasound to guide placement is useful.
- Place a small-bore (10–14 F) intercostal drain. Clamp intermittently to limit flow to 1 L in the first hour. Rapid drainage can cause pulmonary oedema especially if re-expansion of the collapsed lung is associated with a pneumothorax. Once drained generally removed.
- A more expansive drainage process may be needed with significant empyema which requires antibiotics and drainage of viscous infected fluids. As ever take specialist advice.