Pleural effusions

Question 1

What is the pathophysiology behind pleural effusions?

Answer 1

Excess pleural fluid production and reduced pleural fluid drainage

Question 2

Physical examination findings expected

Answer 2

Reduced breath sounds, dull to percussion, reduced vocal resonance

Question 3

Causes of pleural effusions

Answer 3

Transudative/Systemic: cardiovascular, hepatic, renal failure / conditions

Exudative/Inflammatory/Infection: respiratory - e.g. pneumonia ; inflammatory - e.g. RA, SLE

Question 4

What is the diagnostic criteria to differentiate transudate and exudate?

Answer 4

Lights’ criteria - to rule IN exudation (if one or more fulfilled):

• pleural fluid LDH : serum LDH - >0.6
• pleural fluid protein : serum protein - >0.5
• pleural fluid LDH >2/3 upper limit of normal

Question 5

Describe the pleural drainage of the lungs

Answer 5

2 layers - parietal and visceral pleura, eventually both drain into the subclavian veins

Parietal pleura –> follow intercostal vessels, drain into para-sternal nodes, bronchomediastinal nodes and then internal intercostal nodes before thoracic duct –> subclavian

Visceral pleura –> tracheomediastinal –> thoracic duct –> subclavian

Question 6

Management options?

Answer 6

Depends on transudative vs exudative etiology.

Essentially treat the underlying cause!