Atelectasis

Question 1

What is atelectasis. Give a brief description.

Answer 1

Atelectasis is either incomplete expansion or collapse of previously inflated lung.

It can be divided into three types:

• Resorption
• Complression
• Contraction

Atelctasis is usually a reversible disorder as the affected lung can be re-expanded.

Atelectasis results in hypoxaemia, hypercapnoea and infection.

Question 2

Describe resorptive atelectasis.

Answer 2

Absorptive atelctasis results from complete blocking of an airway with unchanged blood flow to the area distal to the blockage.

This leads to ongoing absorption of the oxygen trapped in the affected space. As the volume decreases, the affected lung collapses and the mediastinum shifts towards the affected zone.

This type of atelectasis is more significant for patients on oxygen therapy -> less nitrogen to maintain the lung volume -> more collapse.

Question 3

Describe compression atelectasis.

Answer 3

The pleural space fills with fluid, blood, air or tumour and compresses the adjacent lung. The mediastinum moves away from the affected lung.

Question 4

Describe contraction atelectasis.

Answer 4

Fibrotic changes in the lung parenchyma prohibit full expansion.

Question 5

Give four causes of compressive atelectasis. *

Answer 5

• CCF
• Pleural effusion
• Pneuomthorax
• Peritonitis

NB: Asthma does **not ** cause compressive atelectasis.

Question 6

Can loss of surfactant result in atelectasis?

Answer 6

Yes.