Developmental Aspects of Lung Disease

Question 1

What are the stages of lung morphogenesis?

Answer 1

Embryonic - 3-8 weeks

Pseudo-glandular - 5-17

Canalicular - 16 - 26

Saccular - 24 - 38

Alveolar - 36 weeks - 2/3 years

Question 2

What happens during the embryonic and pseudoglandular stages of lung development?

Answer 2

Formation of :

Major Airways, Bronchial tree and portions of respiratory parenchyma, acinus

Embryonic: appearance of lung buds and main pulmonary arteries

Pseudoglandular: All conducting airways and accompanying blood vessels form

Question 3

What is meant by respiratory parenchyma?

Answer 3

lung tissue, including bronchioles, interstitium and alveoli

Question 4

What happens during the canalicular stage of lung development?

Answer 4

Last generations of the lung periphery formed

Epithelial differentiation - acinai are replacing columnar epithelium with squamous epithelium

Air-blood barrier formed

Question 5

What is significant about the canaliculi stage?

Answer 5

Life outside of the uterus is possible after the canalicular stage

Question 6

What happens during the saccular stage?

Answer 6

Expansion of air spaces

Surfactant detectable in amnionic fluid

Question 7

What happens during the alveolar stage?

Answer 7

Secondary septation

Question 8

Which stages are organogenesis

Which are differentiation?

Answer 8

Organogenesis (embryonic and pseudoglandular)

Differentiation (cannalicular and saccular)

Question 9

What are the common congenital abnormalities

Answer 9

Upper

• Laryngomalacia and tracheomalacia
• Tracheo-oesphageal fistula

Lower

• CPAM
• Congenital Diaphragmatic Hernia

Question 10

How are congenital abnormalities detected during antenatal scanning

Answer 10

US

MRI

Question 11

How are congenital abnormalities detected in a newborn

Answer 11

• Tachypnoea
• Respiratory distress
• Feeding issues

Question 12

How are congenital abnormalities detected in childhood

Answer 12

• stridor/wheeze
• recurrent pneumonia
• chronic cough
• feeding issues

Question 13

Describe laryngomalacia

Answer 13

• softening of larynx
• infants > 6 w.
• stridor, worse on feeding/upset/excited
• improve within 1y
• concern if failure to thrive/apnoeas

Question 14

Describe tracheomalacia

Answer 14

• healthy baby/genetic disease/external compression (tumour, vessel)
• barking cough, recurrent croup
• stridor wheeze
• SOB on exertion
• physio + Abx if unwell
• natural resolution

Question 15

Describe Trachea-oesophageal fistula

Answer 15

• might have oesophageal atresia (abnormally closed passage)
• antenatal or postnatal diagnosis

Question 16

What are the symptoms of Trachea-oesophageal fistula

Answer 16

• choking
• colour change
• cough w/feeding
• unable to pass NG tube
• can cause tracheomalacia, strictures, leak, reflux

Surgical repair

Question 17

Describe Congenital pulmonary airway malformation (CPAM)

Answer 17

• abnormal non-functioning tissue
• mostly antenatally
• sporadic
• resolve in utero
• conservative management if asymptomatic
• surgery
• risk of cancer

Question 18

Describe Congenital diaphragmatic hernia

Answer 18

• diaphragm develops 7-18 w.
• hernia= improper closure of diaphragm
• left side> right side
• BUT right side WORSE
• antenatal diagnosis
• surgery
• prognosis depends on lung hypoplasia

Question 19

How is the diaphragm formed?

Answer 19

Various sheets of primitive tissue move towards the centre of the diaphragm.

Question 20

What are the outcomes of diaphragmatic hernia?

Answer 20

Pulmonary hypoplasia

Persistant pulmonary hypertension

Question 21

What are the functional changes in the lung at birth?

Answer 21

Change from fluid secretion to fluid absorption

Pulmonary vasodilation

Question 22

What is Transient tachypnea of the Newborn?

Answer 22

• C-section= fluid in lungs
• Resolves in 1-2 d

Question 23

Describe respiratory distress syndrome

Answer 23

• Surfactant deficiency
• Antenatal steroids
• Surfactant replacement
• Ventilation

Question 24

Describe bronco-pulmonary dysplasia

Answer 24

• Premature
• Need O2 therapy
• ↑ risk of resp disease