Resp - Pleural Effusions

Question 1

what is a pleural effusion? what are the 2 types?

Answer 1

Presence of excess fluid in pleural space (between visceral and parietal pleura).
1. Transudate: protein <35 g/L, due to increased hydrostatic pressure or decreased osmotic pressure

2. Exudate: protein >35 g/L, due to increased microvascular permeability following disease or vascular injury

Question 2

name possible causes for a transudative pleural effusion

Answer 2

More likely to be bilateral.

Common:

• CHF
• liver cirrhosis
• hypoalbuminaemia
• peritoneal dialysis

Less common:

• hypothyroidism
• mitral stenosis
• SVC obstruction (eg secondary to lung cancer)
• constrictive pericarditis
• Meig’s syndrome (benign ovarian tumour, ascites and pleural effusion)

Question 3

name possible causes for an exudative pleural effusion

Answer 3

Common:

• malignancy (esp. if large unilateral effusion) - most commonly lung cancer in men, breast cancer in women, or malignant mesothelioma
• pneumonia (peri-pneumonic effusion)

Less common:

• pulmonary infarction secondary to PE
• autoimmune disease causing inflammation, e.g. RA, SLE
• TB
• benign asbestos effusion
• complication of acute MI (Dressler’s syndrome)
• adverse drug reactions (rare) - methotrexate, amiodarone, nitrofurantoin, phenytoin, beta-blockers

Question 4

describe the symptoms caused by pleural effusion

Answer 4

Effusion has to be quite large before it causes any signs and symptoms, although most malignant effusions are symptomatic.

• gradual dyspnoea and orthopnoea
• cough
• pleuritic chest pain

Question 5

describe the signs caused by pleural effusion

Answer 5

• tracheal deviation (displaced away from lesion in large unilateral effusion)
• decreased chest wall movement on affected side
• stony dullness on percussion
• decreased breath sounds
• decreased vocal fremitus
• pleural friction rub

Question 6

which investigations would you request for a pt with pleural effusion?

Answer 6

1. bloods
2. CXR
3. thoracocentesis (diagnostic aspiration)
   - LDH and protein
   - MC and S
   - AFB
   - +/- TB culture if suspected

Question 7

which CXR features suggest a pleural effusion?

Answer 7

Uniform opacity with:

• meniscus sign
• loss of costophrenic angle
• obscured hemidiaphragm
• tracheal deviation away from affected side (if large effusion)

Question 8

what are Light’s criteria?

Answer 8

If protein in a pleural fluid sample is 25-35 g/L, sample considered an exudate if at least 1 of:

1. sample protein/serum protein >0.5
2. sample LDH/serum LDH >0.6
3. sample LDH >2/3 upper limit of normal for serum LDH

Question 9

what does the presence of RBCs in a pleural fluid sample suggest?

Answer 9

Can be caused by:

• malignancy
• PE with infarction
• trauma
• benign asbestos effusion
• post-cardiac injury syndrome

Haematocrit should be measured - if >1/2 pt’s serum haematocrit = haemothorax. Not significant if <1%.

Question 10

how would you manage a pt with a pleural effusion?

Answer 10

Management should be aimed at underlying disease. If a transudate is confirmed, aspiration should be avoided.

1) small asymptomatic effusions may be managed by observation
2) tapping fluid can give symptomatic relief but likely to re-form. No more than 1.5L should be removed at once as fluid shifts can cause pulmonary oedema.
3. chest drain can be inserted for controlled drainage of effusion, e.g. in empyema or haemothorax.
4. pleurodesis: injection of sclerosant to cause adhesion of visceral and parietal pleura, and to help present recurrence of effusion.