Pleural Effusion

Question 1

What are the common causes of pleural effusions?

Answer 1

Congestive heart failure (bilateral)
Infection
Malignancy (unilateral)

Question 2

What is the difference between transudate and exudate pleural effusions?

Answer 2

Transudate: low protein <30g. Systemic illness causing a imbalance between oncotic and hydrostatic pressures.

Exudate: high protein >30g/L. Local disease effecting accumulation or clearance of fluid.

Question 3

Causes of exudate pleural effusions

Answer 3

Malignancy (lung breast pleural)
Infection (pneumonia, empyema, pleuritis, viral)
Autoimmune (rheumatoid, SLE)
Vascular (PTE) 
Cardiac (pericarditis, CABG)
Resp (haemothorax, chylothorax)
Abdominal (subphrenic abcess, pancreatitis)
Yellow nail syndrome

Question 4

Causes of transudate pleural effusions

Answer 4

Cardiac (CCF, PTE)
Liver (ascities, cirrhosis)
Renal (glomerulonephritis, nephrotic syndrome)
Ovarian (Meigs syndrome)
Autoimmune (sarcoidosis)
Thyroid (myxoedema, hypothyroid)

Question 5

What’s lights criteria

Answer 5

Used to distinguish between transudate and exudate protein 25-35g/L. Requires total protein and lactate dehydrogenase from blood and pleural fluid.

Exudate :

• pleural fluid protein to serum protein ratio >0.5
• pleural fluid LDH to serum LDH ratio >0.6
• pleural fluid level >2/3 of upper limit of normal serum LDH

Question 6

When should a chest tube be placed in patients with pleural effusion and pleural infection?

Answer 6

If the fluid is purulent or turbid,
Or
If the fluid is clear with a pH <7.2

Question 7

A pleural pH of what indicates a complex parapneomonic effusion or empyema?

Answer 7

PH <7.2