Developmental aspects of lung disease

Question 1

what are the 5 stages in lung morphogenesis?

Answer 1

1. embryonic
2. pseudo-glandular
3. canalicular
4. saccular
5. alveolar

Question 2

when is extra-uterine life possible?

Answer 2

at late canalicular/early saccular stage

Question 3

what happens in the embryonic stage of lung morphogenesis?

Answer 3

a single tube-the oesophagus branches off to form the trachea. Cells of the trachea are cuboidal and far from the blood vessels so gas exchange cannot take place

Question 4

what happens in the pseudoglandular stage of lung morphogenesis?

Answer 4

lungs tissue resembles endocrine tissue, branching of bronchi and bronchioles takes place to form conductive airways. acinus formed

Question 5

what is the canalicular stage of lung morphogenesis?

Answer 5

last generations of the lung periphery formed, epithelium differentiates into squamous epithelium and air-blood barrier is formed.

Question 6

what is the saccular stage of lung development?

Answer 6

air spaces expand and surfactant is detectable in the amnionic fluid

Question 7

what is the alveolar stage of lung morphogenesis?

Answer 7

secondary septation of alveoli which begins in utero but continues ater birth.

Question 8

what is airway stenosis and in what stage of lung development is it likely to originate from?

Answer 8

narrowing of the airways, originates in the earlier stages of lung morphogenesis

Question 9

what is airway malacia and in what stage of lung development is it likely to originate from?

Answer 9

trachea and bronchi are floppy, originates in earlier stages of lung morphogenesis

Question 10

what is pulmonary agenesis/hypoplasia and in what stage of lung development is it likely to originate from?

Answer 10

incomplete development of the lungs, resulting in an abnormally low number or size of bronchopulmonary segments or alveoli, originates in earlier stages of lung morphogenesis

Question 11

what is a tracheo-oesophageal fistula and in what stage of lung development is it likely to originate from?

Answer 11

abnormal connection between primitive gut and airway. originates in earlier stages of lung morphogenesis

Question 12

what are bronchial cysts and in what stage of lung development is it likely to originate from?

Answer 12

congenital malformations of the bronchial tree, likely to occur in late stages of lung morphogenesis.

Question 13

what is lobar emphysema and in what stage of lung development is it likely to originate from?

Answer 13

air can be drawn into the lungs but not expelled out. likely to occur in late stages of lung morphogenesis

Question 14

what is cystadenomatoid malformation and in what stage of lung development is it likely to originate from?

Answer 14

varying number and sizes of cysts in one lobe of lung. occurs in later lung morphogenesis

Question 15

what is sequestration and in what stage of lung development is it likely to originate from?

Answer 15

aberrant formation of segmental lung tissue that has no connection with the bronchial tree or pulmonary arteries occurs in later stages lung morphogenesis

Question 16

when are there presenting features of developmental lung diseases?

Answer 16

• in fetal ultrasound
• in newborn
• in childhood or adulthood

Question 17

what are the presenting features of developmental lung diseases in the newborn?

Answer 17

tchypnea
respiratory distress (chest wall retraction)

Question 18

what are the presenting features of developmental diseases in childhood and in adulthood?

Answer 18

stridor/wheeze
recurrent pneumonia
incidental finding

Question 19

what are the symptoms of tracheo-bronchomalacia?

Answer 19

• barking/seal-like cough
• early onset/ recurrent croup
• breathlessness of exertion
• stridor/wheeze

Question 20

what is the management of tracheo-bronchomalacia?

Answer 20

• airway clearance physiotherapy
• antibiotics
• NOT asthma treatment

Question 21

what is a possible risk of Pulmonary adenomatoid malformation?

Answer 21

it may become malignant

Question 22

how does the diaphragm develop?

Answer 22

membranes develop towards the centre of the embryo until the fuse in the centre

Question 23

what may happen if the diaphragm doesn’t develop correctly?

Answer 23

diaphragmatic hernia

Question 24

what cn a diaphragmatic hernia result in?

Answer 24

pulmonary hypertension and pulmonary hypoplasia

Question 25

what is transient tachypnea of the newborn (wet lung)?

Answer 25

amnionic fluid remains in the lung after birth, resolves in 24-48hrs

Question 26

what is a surfactant deficiency called?

Answer 26

hyaline membrane disease (respiratoty distress syndrome)

Question 27

what causes hyaline membrane disease?

Answer 27

a build up of a membrane of dead cells and proteins in the alveoli caused by a deficiency of surfactant.

Question 28

what is the treatment fro hyaline membrane disease?

Answer 28

• Antenatal glucocorticoids
• Surfactant replacement
• Supportive

until endogenous surfactant production by day 5

Question 29

what are the antenatal causes of adult lung disease (COPD)?

Answer 29

• in utero nicotine exposure
• fetal infection
• maternal nutrition
• low birth weight/prematurity (antenatal steroids)
• maternal micronutrients/vitamins

Question 30

what are the post-natal causes of adult lung disease?

Answer 30

• infection (Barker hypothesis)
• growth
• ETS (exposure to tobacco smoke) (+/- alpha 1 AT deficiency)
• environmental pollution
• micronutrients/vitamins

Question 31

what is the chronic neonatal lung disease?

Answer 31

chronic inflammation in the lungs causes damage and scarring which reduces compliance.

Question 32

what are some of the causes of chronic neonatal lung disease?

Answer 32

• antenatal infection
• barotrauma/ oxygen toxicity
• patent ductus arteriosus
• ventilation
• genetic

Question 33

what does pre-natal nicotine exposure do to lungs?

Answer 33

-Lung hypoplasia
-Reduced alveolarisation
-Reduced lung function (small airways)
causing Increased incidence wheeze syndromes
-Increased susceptibility to infection

Question 34

what does remodelling in asthma cause?

Answer 34

• Increased bronchial responsiveness
• Increase mucus secretion
• Airway oedema
• Airway narrowing