Prematurity and pre-natal medicine Flashcards Preview

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Flashcards in Prematurity and pre-natal medicine Deck (28):
1

How much of the respiratory system has developed by weeks 5-6 of gestation?

1. Mainstem bronchi
2. Secondary bronchi
3. Development of caudal growth
4. Tertiary bronchi

2

When is the pseudoglandular period?

6 - 16 weeks

3

What occurs during the pseudoglandular period?

14 generations of branching terminal bronchioles formed

NO respiratory bronchioles

Co-branching of pulmonary arteries

4

When is the canilicular period?

16 - 26 weeks

5

What occurs during the canilicular period?

1. Terminal bronchioles divide into respiratory bronchioles
2. Alveolar ducts

6

When is the saccular period?

28 - 36 weeks

7

What occurs during the saccular period?

1. Terminal sacs form
2. Capillaries in close contact with primitive alveoli

8

What do the terminal sacs give rise to?

Alveoli

9

When is the alveolar period?

8 months to childhood

10

What occurs during the alveolar period?

Maturation of alveoli

11

How many terminal sacs are there at birth?

20-70 million

12

How long does terminal sac formation continue for?

Until about 8 years old

13

How many terminal sacs are there in the mature lung?

300-400 million

14

How does the blood-air barrier change at 8-9 months?

Sac lining cells (type I pneumocytes) are thinner

Capillaries protrude into alveolar sacs

Increasing contact points for gas exchange

15

When does surfactant start being produced?

End of 6th month when type II pneumocytes appaer

16

What is surfactant?

Saturated and unsaturated phospholipids, proteins and carbohydrates

Reduces surface tension

Continuous synthesis, secretion and re-uptake cycle

17

What causes the fall in pulmonary vascular resistance at term birth?

1. Lung distension
2. Alveolar oxygen tension
3. Nitric oxides
4. Prostacyclins
5. Endothelins

18

What are the effects of prematurity on lung function?

1. Small lungs
2. Reduced number of alveoli, which are immature
3. Reduced epithelial-endothelial contact
4. Deficient surfactant
5. Retained lung fluid

19

What signs might you see in an infant with respiratory distress syndrome?

1. Tachypnoea
2. Dyspnoea
3. Grunting
4. Nasal flaring
5. Subcostal recession
6. Cyanosis
7. Tachycardia
8. Inability to feed

20

How is RDS diagnosed?

1. History
2. Examination
3. Chest x-ray
4. Blood gas analysis

21

How is RDS treated?

1. Prenatal steroids to stimulate lung maturation in women at risk of having preterm birth
2. Postnatal surfactant

22

When can primitive gas exchange start?

22 - 24 weeks

23

What developmental problems may develop in the embryonic period?

1. Agenesis/aplasia
2. Tracheal stenosis
3. Congenital cysts

24

What developmental problems may develop in the pseudoglandular period?

1. Diaphragmatic hernia
2. Hypoplasia following amniocentesis

25

What developmental problems may develop in the canilicular period?

1. Hypoplasia
2. Potter's

26

What is the liquid in the lungs?

NOT aspirated amniotic fluid or plasma

Actively secreted by the lungs

27

What promotes clearance of liquid in the lungs at birth?

1. Active sodium reabsorption
2. Lymphatic drainage
3. Pulmonary blood vessels
4. Squeezed out during birth

28

When does lung liquid start to clear?

2-3 days before term delivery