Developmental aspects of lung disease

Question 1

What occurs in the embryonic stage of lung morpgogenesis?

Answer 1

The laryngotracheal groove forms from the gut tube. The trachea and the lung buds then form.
The oesophagotracheal septum then develops and separates the oesophagous from the trachea.
The bronchial buds then form and they grow down in to the pleural space.
By week 8 the lung shape has formed.

Question 2

What happens in the pseudoglandualr stage (5-17weeks)?

Answer 2

The bronchial buds then form and they grow down in to the pleural space.
The conducting zone is created.
Blood vessels start to grow in and cilia are seen.

Question 3

Explain what occurs in the Canicular stage.

Answer 3

Gas exchange structure start to be seen. Pneumocytes begin to be formed by cells specialising, some that form surfactant by begin to emerge.

Question 4

What occurs in the Saccular stage?

Answer 4

More blood vessels form/grow in. Interstitial fluid starts to thin out.

Question 5

Describe what happens in the alveolar stage.

Answer 5

The alveloar change size, shape and function (slightly). More alveoli will be be formed.

The majority of this stage occurs after a baby is born and in to childhood.

Question 6

What are some of the most common (although still very rare) upper respiratory congenital abnormalities?

Answer 6

• Tracheal agenesis
• Tracheal Stenosis
• Tracheomalacia
• Tracheo-oesphageal fistula

Question 7

What happens in tracheal agenesis?

Answer 7

Is the abscence or incomplete development of the trachea. There are different types of the condition depending on whether there is an trachea and how much there is.

Question 8

How does tracheal agenesis present?

Answer 8

The patient will be in acute respiratory distress and will not be able to be intubated.

Question 9

What is tracheal stenosis?

Answer 9

The tracheal cartilage rings are completed too early in the growth so there can be a generalised or segmental narrowing of the trachea.

Question 10

When will tracheal stenosis present?

Answer 10

At birth or within the first year.

Question 11

What is tracheomalacia?

Answer 11

The tracheal cartilage is soft and can cause partial or complete collapse of the trachea.

Question 12

What is the presentation and management of tracheomalacia?

Answer 12

Barking cough, recurrent croup, breathless on exerction and stridor/wheeze

It will resolve naturally as the cartilage gets firmer. When unwell physio and antibiotics are used.
Bronchodilator should NOT be used, as this will worsen the condition.

Question 13

What is a tracheo-oesophageal fistula?

Answer 13

It is an abnormal connection between trachea and oesphagus.

This is normally a GI problem and is assoctiaed with genetic conditions such as Down’s syndrome.

Question 14

How does a tracheo-oesphageal fistula present?

Answer 14

Choking
Colour change
Cough with feeding
Unable to pass an NG tube

Question 15

How do you treat a tracheo-oesophageal fistula and what are the complications?

Answer 15

Surgical repair

Complications: tracheomalacia, strictures, leak and reflux.

Question 16

What are the “common” lower (brocho-pulmonary) respiratory cogenital abnormalities?

Answer 16

Lung agenesis/Pulmonary Hypoplasia
Bronchogenic cyst
CPAM
Cogenital Diaphramatic Hernia

Question 17

What are the presnting features generally for respiratory cogenital abnormalities?

Answer 17

In newborn: tachypnoea (rapid breathing), respiratory distress (using stomach to breath), feeding issues.

Childhood:Stridor/wheeze, recurrent pneumonia, cough, feeding issues

Question 18

What does CPAM stand for?

Answer 18

Cogenital Pulmonary Airway Malformation

Question 19

Give details about CPAM

Answer 19

It is abnormally functioning lung tissue, it occurs sporadically.
80% are detected antenatally
May resolve in utero

Question 20

What is the managemnet of CPAM?

Answer 20

Conservative managemnet in asymptomatic

Surgical intervention may be required.

Question 21

Explain about congenital diaphragmatic hernia

Answer 21

Affects 1 in 2500 births
More common on left side than right

Surgical repair of diaphragm is required

Prognosis depends on the degree of lung hypoplasia.

Question 22

What is hypoplasia?

Answer 22

Imcomplete or arrested development of an organ.

Question 23

Why does transient tachypnoea of newborn occur?

Answer 23

Normally at birth fluid in the lungs is squeezed out as the baby passes through the birth canal and is the absorbed, so that the lungs can then be filled with air.

If this doesn’t happen (e.g. in a C-section), then the fluid may stay in the lungs for 1-2 days before it is completely absorbed, so the babay will need to breath more rapidly.

Question 24

When do type II pneumocytes form through differentiation?

Answer 24

Between 24-34 weeks

Question 25

What is respiratory distress syndrome (RDS) (hyaline membrane disease)?

Answer 25

It is when an infant has a surfactant deficiency, so has to work alot harder to breath.

Question 26

How do you treat RDS?

Answer 26

Give antenatal steroid if mother is likely to give birth early.

Surfactant replacement

Ventilation

Give/monitor nutrition

Question 27

What is chronic lung disease with prematurity also called and what is it possibly linked to?

Answer 27

Bronchopulmonary displasia

It maybe linked to future COPD and is associated with increased childhood respiratory morbidity.

Question 28

What is remodelling?

Answer 28

The alteration of airway structure following external influence, such as environmental exposures, chronic diseases of childhood and infection.

This occurs due to these influences interfering with inter-cellular signalling.

Question 29

Describe the remodelling seen in asthma.

Answer 29

Chronic inflammation due to increased bronchial responsiveness.
Increased mucus secretion
Airway oedema
Airway narrowing

Question 30

Explain the remodelling that occurs in chronic lung disease and why it occurs.

Answer 30

Chronic inflammation occurs due to interference with inter-cellular signalling and the toxicity of the treatment.

Question 31

Why do early life respiratory problems lead to an increased risk of adult lung disease?

Answer 31

They reduce normal growth and lung function.