Respiratory - Pleural Disease

Question 1

What is the pleural cavity?

Answer 1

A POTENTIAL SPACE created by the the pleural surfaces:

• parietal pleura
• visceral pleura

Question 2

What is the pathophysiology of a pneumothorax.

Answer 2

A disorder where air enters the pleural space, separating the pleural seal and causing subsequent atelectasis of the lung.

Question 3

What are the causes of pnuemothorax?

Answer 3

• spontaneous
• trauma
• iatrogenic (e.g. central line or pacemaker insertion)
• lung pathology (e.g. infection)

Question 4

What is the investigation of choice for a simple pneumothorax?

Answer 4

Erect CXR

Note CT thorax can be used to detect a small pneumothorax, or to assess the size of a pneumothorax.

Question 5

What are the signs of simple pneumothorax on CXR?

Answer 5

• area between the lung tissue and chest wall where there are no lung markings
• line demarcating the edge of the lung

Question 6

Describe how to measure the size of a simple pneumothorax on CXR.

Answer 6

Measure horizontally from the lung edge to the inside of the chest wall, at the level of the hilum.

Question 7

How should a simple pneumothorax be treated in the following conditions:

a) no SOB; pneumothorax size <2cm

b) SOB; pneumothorax size >2cm

c) bilateral pneumothoraces

Answer 7

a) no treatment required; it will spontaneously resolve. Follow up in 2-4 weeks.

b) aspiration and reassessment; if aspiration fails twice, insert a chest drain.

c) chest drain

Question 8

What is the pathophysiology of a tension pneumothorax?

Answer 8

Trauma to the chest wall creates a one-way valve that lets air in to - but not out of - the pleural space. This causes air to accumulate within the pleural cavity, increasing pressure within the thorax.

As pressure rises, the mediastinum is pushed across, the large vessels are kinked and cardiorespiratory arrest can ensue.

Question 9

What are the signs of a tension pneumothorax?

Answer 9

• tracheal deviation away from the side of pneumothorax
• reduced air entry to affected side
• hyper-resonant percussion on affected side
• tachycardia
• hypotension

Question 10

What is the management of a tension pneumothorax?

Answer 10

Insert a large bore cannula into the second intercostal space, in the midclavicular line on the affected side.

If tension pneumothorax is suspected DO NOT wait for investigations. Once the pressure is relieved with a cannula, a chest drain is required for definitive management.

Question 11

Where is a chest drain inserted?

Answer 11

Triangle of safety:

Super border: base of the axilla

Inferior border: 5th intercostal space

Posterior border: lateral edge of Latissimus dorsi

Anterior edge: lateral edge of the Pectoris major

Question 12

In a chest drain, why is a needle inserted just above the rib?

Answer 12

Avoids the intercostal neurovascular bundle that runs below the rib.

Question 13

What discharge advice should be offered to patients with pneumothorax?

Answer 13

No flying or driving until the pneumothorax has resolved.

Question 14

What is a pleural effusion?

Answer 14

A collection of fluid within the pleural cavity.

The fluid can be either exudative (high protein count), or transudative (low protein count).

Question 15

Give some causes of exudative pleural effusion.

Answer 15

• lung cancer
• tuberculosis
• rheumatoid arthritis
• pneumonia
• drugs

Question 16

Give some causes of transudative pleural effusion.

Answer 16

• congestive heart failure
• hypoalbuminaemia (e.g. nephrotic syndrome, peritoneal dialysis)
• hypothyroidism
• pulmonary embolism

Question 17

If pleural fluid protein level between 25 and 35g/L, how can transudative and exudative causes of pleural effusion be determined?

Answer 17

Light’s criteria says pleural effusion is exudative if:

Pleural fluid / serum protein > 0.5

or

Pleural fluid / serum LDH > 0.6

or

Pleural fluid LDH >2/3 the upper limit of normal

Question 18

Presentation of pleural effusion.

Answer 18

• shortness of breath
• dullness to percussion over the effusion
• reduced breath sounds
• tracheal deviation away from the effusion

Question 19

What are the CXR findings consistent with pleural effusion?

Answer 19

• blunting of costophrenic angle
• fluid in the lung fissures
• large effusions will have a meniscus
• tracheal / mediastinal deviation

Question 20

How should pleural effusion be investigated?

Answer 20

• CXR
• ECG

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

Question 21

How should pleural effusion be treated?

Answer 21

Small effusions will resolve with treatment of the underlying cause.

Large effusions need pleural aspiration or chest drain.

NOTE never insert a chest drain unless the diagnosis is well established, otherwise draining all fluid may hinder the opportunity to obtain pleural biopsies.

Question 22

What is empyema?

Answer 22

An infected pleural effusion.

Question 23

Presentation of empyema.

Answer 23

Patient with improving pneumonia but new or ongoing fever.

Question 24

Investigation of empyema.

Answer 24

Pleural aspiration, showing:
- pus
- pH < 7.2
- low glucose
- high LDH

Question 25

Management of empyema.

Answer 25

Empyema is treated with antibiotics and an URGENT chest drain to remove the pus.