Developmental Aspects of Lung Disease

Question 1

What are the stages in lung morphogenesis?

Answer 1

Embryonic, Pseudoglandular, canalicular, saccular and alveolar

Question 2

Explain the embryonic stage

Answer 2

3-18 weeks
Lung buds develop and divide to lobar buds which are derived from mesoderm
Mesoderm forms blood vessels

Question 3

Explain the pseudoglandular stage?

Answer 3

5-17 weeks
Branching of airways and 16-25 primitive segmental bronchi formed
Develop cilia and mucous glands

Question 4

Explain canalicular stage?

Answer 4

16-26 weeks
Lungs develop distal architecture. Terminal bronchioles, alveolar sacs and capillaries formed
Type 1 and 2 pneumocytes appear

Question 5

What is the limit of viability?

Answer 5

24 weeks
Can be when the baby can be born premature and survive in intensive care

Question 6

Explain the saccular stage

Answer 6

24-38 weeks
Alveolar sacs grow and become well formed
More surfactant produced
Bronchioles continue to elongate
Interstitial tissue becomes thinner

Question 7

Explain the alveolar stage

Answer 7

36 weeks - term and beyond
Can breath independently
Cells are well differentiated and vascular more developed

Question 8

How many alveolar sacs are there approx.?

Answer 8

Around 200-300 million at 3-8 years

Question 9

How is congenital abnormalities diagnosed by antenatal screening?

Answer 9

Ultrasound and MRI

Question 10

What are the signs of congenital abnormalities in newborns?

Answer 10

If they are tachypnoea, in respiratory distress or have feeding issues

Question 11

What are the signs of congenital abnormalities in childhood?

Answer 11

Stridor/wheeze, recurrent pneumonia, cough and feeding issues

Question 12

Explain laryngomalacia

Answer 12

There is floppiness of the airway and dynamic abnormal collapse of larynx or voice box
Commonly seen in infants

Question 13

What are the symptoms of laryngomalacia?

Answer 13

Stridor, worse with feeding or when upset or excited

Question 14

What is the management of laryngomalacia?

Answer 14

Will improve within the first year so usually no interference
Concern if affects feeding, growth or causes apnoea’s.

Question 15

Exaplain tracheomalacia

Answer 15

Is floppiness of the trachea
Can be isolated in healthy infants and associated with genetic conditions.
May be caused by external compression (vessels, tumour)

Question 16

What is the presentations of tracheomalacia?

Answer 16

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

Question 17

What is the management for tracheomalacia?

Answer 17

No intervention usually required but can includes physio and antibiotics when unwell due to infection
Natural history resolution with time

Question 18

Explain tracheooesophageal fistula?

Answer 18

Abnormal connection between trachea and oesophagus
Majority have associated oesophageal atresia and there is association with genetic condtitons

Question 19

When can tracheo-oesophageal diagnosed?

Answer 19

Can be antenatally or postnatally (more common)

Question 20

What are the presentations of tracheo-oesophageal?

Answer 20

Choking, colour change, cough when feeding and unable to pass NG (nasal gastric)

Question 21

What is the treatment for tracheo-oesophageal?

Answer 21

Surgical repair

Question 22

What are the complications of surgery to tracheo-oesophageal?

Answer 22

Tracheomalacia, strictures, leak and reflux

Question 23

Explain congenital pulmonary airway malformation (CPAM)?

Answer 23

Abnormal non-functioning lung tissue
Most detected antenatally
Occurs sporadically so no association to underlying health condition

Question 24

What is the management for CPAM?

Answer 24

May resolve spontaneously in utero but follow up
Conservative management if asymptomatic
Surgical intervention may be required if symptoms and unwell

Question 25

What is the risk with CPAM?

Answer 25

Possible risk of malignant change?

Question 26

Explain congenital diaphragmatic hernia?

Answer 26

An absent or partially formed diaphragm results in an abnormal opening (hernia) that allows the stomach and intestines to move into the chest cavity and crowd the heart and lungs Usually left side

Question 27

What is the most common type of congenital diaphragmatic hernia?

Answer 27

Bochdalek

Question 28

What is the management of congenital diaphragmatic hernia?

Answer 28

Surgical repair Prognosis then depends on degree of lung hypoplasia

Question 29

What is neonatal lung disease?

Answer 29

Significant changes occur at birth after first breath

Question 30

What is transient tachypnoea of newborn?

Answer 30

Fluid in lungs not moving Due to lung inflation when child moves through birth canal and having vigorous breath Usually Caesarean section

Question 31

When does transient tachypnoea of newborns improve?

Answer 31

Within 1 -2 days

Question 32

Explain Respiratory Distress Syndrome (RDS)

Answer 32

Due to surfactant deficiency and also called hyaline membrane disease Occurs in preterm infants but some term infants

Question 33

What is the treatment for RDS?

Answer 33

Antenatal steroids for lung development Surfactant replacement - directly to lungs by tube Appropriate ventilation and nutrition

Question 34

Explain Bronchopulmonary dysplasia?

Answer 34

Chronic lung disease associated with prematurity where ongoing O2 requirement at term Multifactorial causes

Question 35

What does Bronchopulmonary dysplasia mean for the newborn?

Answer 35

Associated with increased childhood resp. morbidity Leads to chronic obstructive picture - as smaller lungs and increased O2 requirement

Question 36

What individual factors affects relationship between foetal/child and adult lung disease?

Answer 36

Sex, age and height

Question 37

What early life events may affect relationship between foetal/child and adult lung disease?

Answer 37

Parental atopy, education, premature, maternal smoking, birth weight, breastfeeding, peak weight and lung functions

Question 38

What allergic disease can affect the relationship between foetal/child and adult lung disease?

Answer 38

Asthma, Rhinitis, Aeor-/ food allergen and sensitisation

Question 39

What are environmental lifestyle factors affect the relationship between foetal/child and adult lung disease?

Answer 39

Air pollution, second hand smoke exposure, smoking, serum vit D conc., and BMI

Question 40

Explain remodelling

Answer 40

Alteration of airway structure following external influence Leads to abnormalities due to interference of inter-cellular signalling

Question 41

What are the external influences causing alteration of airway (remodelling)?

Answer 41

Environmental exposures Chronic disease of childhood Infection

Question 42

What are the alterations of remodelling seen in airways?

Answer 42

Increased mucous production, inflammatory cells and vasodilation Hypertrophy of smooth muscle, thickening, oedema

Question 43

What resp. disease is remodelling seen in?

Answer 43

Asthma and Chronic lung disease of prematurity

Question 44

What does chronic inflammation lead to?

Answer 44

Increased bronchial responsiveness Increased mucous secretion Airway oedema Airway narrowing

Question 45

What can lung function decline lead to in adults?

Answer 45

COPD