Unilateral pleural effusion

Question 1

Where does fluid collect?

Answer 1

Between the parietal and visceral pleura.

Question 2

Why does fluid accumulate?

Answer 2

· A thin layer of fluid is always present in this space.
· If the normal flow of fluid is disrupted, with either too much produced, or not enough removed, then fluid accumulates.
· This results in a pleural effusion.

Question 3

Which criteria is used for exudate/transudate differentiation?

Answer 3

Light’s criteria.

Question 4

Who is most affected - males or females?

Answer 4

Equal between both sexes but also dependent on cause. Although malignancy pleural effusions more common in women due to breast/gynae malignancies.

Question 5

What is the primary cause?

Answer 5

Imbalance between fluid production and fluid removal.

Question 6

What normally happens with fluid in this space?

Answer 6

· 15ml/day of fluid enters this potential space, primarily from the capillaries of the parietal pleura.
· The fluid is then removed by the lymphatics in the parietal pleura.

Question 7

What abnormally happens with fluid in this space?

Answer 7

· Disruption of fluid regulation from local or systemic derangements.
· Local factors:
- High protein and high LDH - EXUDATE.
- Leaky capillaries from inflammation (infection, infarction, tumour).

· Systemic factors:

• Low protein and low LDH - TRANSUDATE.
• Elevated pulmonary capillary pressure (heart failure, cirrhosis, nephrotic syndrome).

· In practice, transudates are often multi-factorial.

Question 8

What are transudate effusions caused by?

Answer 8

Factors that alterhydrostaticpressure, pleuralpermeability, andoncoticpressure.

Question 9

What does the pleural fluid protein have to be to diagnose a transudate effusion?

Answer 9

<30g/L.

Question 10

What are exudate effusions caused by?

Answer 10

Changesto thelocalfactorsthat influence theformationand absorption of pleural fluid.

Question 11

What does the pleural fluid protein have to be to diagnose a exudate effusion?

Answer 11

> 30g/L.

Question 12

What is the aetiology?

Answer 12

· Rate of fluid formation is greater than that of fluid removal.

Question 13

What is the aetiology of a exudative effusion?

Answer 13

Inflammatory processes/decreased lymphatic drainage:

· LOCAL DISEASE. HIGH PROTEIN.
· Infection - Pneumonia, empyema, pleuritis, fungal.
· Malignancy - Lung, breast, pleural.
· Vascular - PE.
· Autoimmune - RA, SLE.
· Abdominal - Pancreatitis, intra-abdominal abscess.
· Surgery - Post CABG.

Question 14

What is the aetiology of a transudative effusion?

Answer 14

Imbalance of oncotic and hydrostatic pressures:

· SYSTEMIC DISEASE. LOW PROTEIN.
· Cardiac - CHF (elevated capillary pressures).
· Vascular - PE.
· Liver - Ascites and cirrhosis (elevated portal pressures).
· Ovarian - Meigs syndrome.
· Autoimmune - Sarcoid.
· Renal - Nephrotic syndrome (hypoalbuminaemia), peritoneal dialysis, glomerulonephritis.

Question 15

List the strong risk factors.

Answer 15

· CHF.
· Pneumonia.
· Malignancy.
· Recent CABG surgery.

Question 16

List the weak risk factors.

Answer 16

· PE.
· Recent MI.
· Occupational lung disease - asbestos exposure.
· RA, SLE.
· Renal failure.
· Drug induced - nitrofurantoin, dantrolene, valproate, isotretinoin.
· Chylothorax.

Question 17

List the common signs and symptoms.

Answer 17

· Dyspnoea.
· Dullness to percussion over the effusion - compared with the resonant sound of air-filled spaces.
· Pleuritic chest pain - worse on inspiration and exacerbated by cough and movement.
· Cough.
· Quieter breath sounds - over the area of effusion.
· Decreased or absent tactile fremitus - fluid barrier prevents sound waves and vibrations.

Question 18

What investigations would you do if you suspected a patient had a pleural effusion?

Answer 18

· PA and lateral CXR - blunting of the costophrenic angles. 
· Pleural USS. 
· Pleural fluid sample.
· FBC, CRP. 
· CT chest.

Question 19

What would you look at in a pleural fluid sample?

Answer 19

· LDH and protein – indicates an exudate if the ratio of pleural fluid protein to serum protein is >0.5 – absence of these findings the effusion is likely to be a transudate.
· RBCs.
· WBCs.
· pH - needs to be measured with an ABG machine.
· Glucose - almost 100% of effusions due to empyema and rheumatoid arthritis.

Question 20

Differentials?

Answer 20

· Pleural thickening.
· Pulmonary collapse and consolidation.
· Elevated hemidiaphragm - paralysis of the phrenic nerve.

Question 21

What is the treatment for CHF?

Answer 21

· Diuretic - furosemide, bumetanide.
· Physio.
· Therapeutic thoracocentesis and oxygen - if symptomatic and large.

Question 22

What is the treatment for an infective effusion?

Answer 22

· IV abx - co-amoxiclav and metronidazole. 
· Therapeutic thoracocentesis.
· Physio.
· Oxygen - if symptomatic and large. 
· Tube thoracostomy - if empyema.

Question 23

What is the treatment for a malignant effusion?

Answer 23

· Therapeutic thoracentesis.
· Physio.
· Oxygen - if symptomatic and large.

Question 24

What is the treatment for recurrent symptomatic malignant effusions?

Answer 24

· Repeated therapeutic thoracocentesis.
· Pleurodesis - with talc.
· Pleural catheter drainage.

Question 25

Complications?

Answer 25

· Atelectasis/lobar collapse. 
· Pneumothorax following thoracocentesis. 
· Re-expansion pulmonary oedema. 
· Pleural fibrosis - TB. 
· Trapped lung.