Pleural Effusion

Question 1

What is a pleural effusion?

Answer 1

A pleural effusion is a collection of fluid in the pleural cavity.

Question 2

What are exudative causes?

Answer 2

Exudative causes are related to inflammation. The inflammation results in protein leaking out of the tissues in to the pleural space (ex- meaning moving out of). Think of the causes of inflammation:

Lung cancer
Pneumonia
Rheumatoid arthritis
Tuberculosis
Pulmonary embolism 
Kidney Disease
Blocked blood or lymph vessels

Question 3

What are transductive causes?

Answer 3

Transudative causes relate to fluid moving across into the pleural space (trans- meaning moving across). Think of the causes of fluid shifting:

Congestive cardiac failure
Hypoalbuminaemia
Hypothroidism
Meig’s syndrome (right sided pleural effusion with ovarian malignancy)
Increased pressure in blood vessels 
Low blood protein count

Question 4

Presentation?

Answer 4

Shortness of breath
Dullness to percussion over the effusion
Reduced breath sounds
Tracheal deviation away from the effusion if it is massive

Question 5

What investigations are needed?

Answer 5

Chest X-ray

Taking a sample of the pleural fluid

Question 6

What will the chest x-ray show?

Answer 6

Blunting of the costophrenic angle

Fluid in the lung fissures

Larger effusions will have a meniscus. This is a curving upwards where it meets the chest wall and mediastinum.

Tracheal and mediastinal deviation if it is a massive effusion

Question 7

What is the pleural fluid tested for?

Answer 7

Taking a sample of the pleural fluid by aspiration or chest drain is required to analyse it for protein count, cell count, pH, glucose, LDH and microbiology testing.

Question 8

Treatment

Answer 8

Conservative management may be appropriate as small effusions will resolve with treatment of the underlying cause. Larger effusions often need aspiration or drainage.

Pleural aspiration involves sticking a needle in and aspirating the fluid. This can temporarily relieve the pressure but the effusion may recur and repeated aspiration may be required.

Chest drain can be used to drain the effusion and prevent it recurring.

Question 9

What is empyema?

Answer 9

Empyema is where there is an infected pleural effusion.

Suspect an empyema in a patient who has an improving pneumonia but new or ongoing fever.

Pleural aspiration shows pus, acidic pH (pH < 7.2), low glucose and high LDH.

Empyema is treated by chest drain to remove the pus and antibiotics.

Question 10

What are exudative vs transdutaive causes in respect to protein count?

Answer 10

This can be exudative meaning there is a high protein count (>3g/dL) or transudative meaning there is a relatively lower protein count (<3g/dL).

Question 11

Clinical examination

Answer 11

A thorough respiratory examination is required.

On peripheral inspection lookout for nicotine staining of fingers, clubbing (lung cancer), evidence of joint deformity (rheumatoid arthritis) and signs of fluid overload (heart failure).

On closer inspection of the chest, a larger pleural effusion may cause reduced chest movement on the affected side.

Palpation may reveal tracheal deviation away from the affected side.

On percussion, a pleural effusion classically sounds ‘stony’ dull.

When auscultating, breath sounds and vocal resonance are reduced or absent over an effusion.

Question 12

What are can be a potential differential diagnosis?

Answer 12

Breathlessness, cough and pleuritic chest pain are typical presenting features of a pleural effusion but important differentials to consider include:

Infection: such as pneumonia or tuberculosis
Malignancy without effusion
Pulmonary embolism
Pneumothorax

Question 13

Bedside investigations

Answer 13

ECG: to look for a cardiac cause of chest pain and breathlessness or signs of right heart strain which may indicate a pulmonary embolism.
Urine dip: to assess for proteinuria which may indicate nephrotic syndrome.

Question 14

Diagnosis:

Answer 14

Pleural fluid should be sent for biochemistry (protein, LDH and glucose), microbiology (gram stain and culture) and cytology. More specialist tests may be needed depending on the likely cause of the pleural effusion.

If pleural fluid protein is 25-35g/L, Light’s criteria are used to distinguish transudative from exudative pleural effusions.

Question 15

What is Light’s criteria summary for saying a fluid is exudate?

Answer 15

The fluid is an exudate if one or more of the following criteria are met:

Pleural fluid protein divided by serum protein is >0.5
Pleural fluid LDH divided by serum LDH is >0.6
Pleural fluid LDH is >⅔ the upper limit of the laboratory normal value for serum LDH

Question 16

What is the main age of management?

Answer 16

Treat underlying cause

Question 17

What treatment may be considered if pleural effusion reaccumulates?

Answer 17

If the pleural effusion reaccumulates, the following options may be considered:

Long term indwelling chest drain

Pleurodesis (by chest drain or medical thoracoscopy)

• Pleurodesis is a procedure that sticks your lung to your chest wall. This procedure removes the space between your lung and your chest wall (pleural space) so that fluid or air no longer builds up between the layers.

Question 18

Complications of pleural effusions

Answer 18

Larger pleural effusions may cause increasing respiratory compromise.

A parapneumonic effusion is a pleural effusion that forms in the pleural space adjacent to a pneumonia, complications may include empyema and sepsis.

A collapsed lung may relate to pleural procedures carried out during the diagnosis and treatment of a pleural effusion.

Patients with malignancy or pneumonia have a poorer prognosis if a pleural effusion develops.