Foetal Circulation

Question 1

What is the approximate CBV for neonates, infants and children?

Answer 1

• Neonate = 85ml/kg
• Infant = 80ml/kg
• Child = 70ml/kg

Question 2

What is the main difference between infant and foetal circulation?

Answer 2

Foetus = systemic only
Infant = systemic and pulmonary

Question 3

What is the hole in the foetal heart called?

Answer 3

Foramen ovale

Question 4

What is different about foetal Hb?

Answer 4

It has a higher affinity for oxygen

Question 5

Name the shunts in the foetal circulation

Answer 5

1. Ductus arteriosus (hole between pulmonary artery and aorta)
2. Foramen ovale (hole between atria)
3. Ductus venosus (hole between the umbilical vein and inferior vena cava)

Question 6

What does the ductus arteriosus bypass?

Answer 6

Lungs

Question 7

What does the ductus venosus bypass?

Answer 7

Liver

Question 8

What happens to the umbilical vein after birth?

Answer 8

Becomes the round ligament of the liver

Question 9

What happens to the umbilical arteries after birth?

Answer 9

Becomes the vesicle ligaments on the abdominal wall

Question 10

What happens to the ductus venosus after birth?

Answer 10

Becomes the ligamentum venosum

Question 11

What happens to the ductus arteriosus after birth?

Answer 11

Becomes the ligamentum arteriosum

Question 12

What stimulates an infant to take their first breath?

Answer 12

• Lung fluid elimination
• High CO2 levels
• Low O2 levels
• Cold air and noise

Question 13

What effect does the initial breathing have on the body?

Answer 13

• Decreased pulmonary ventilation rate
• Increased O2 conc
• Vasodilation