Introduction to Neonatology

Question 1

What does the CVS begin to form?

Answer 1

Toward the end of the third week

Question 2

When does the heart start beating?

Answer 2

4th week

Question 3

When is the critical period for heart development?

Answer 3

Days 20-50 after fertilisation

Question 4

How does oxygenated blood form the mother enter foetal circulation?

Answer 4

Via the umbilical vein through the ductus venosus

Question 5

How does blood get to the left side of the heart in the foetus?

Answer 5

Via Foramen Ovale

Left Atrium – Left Ventricle – Aorta (Ao)

Question 6

How does blood get to the aorta from the right side of the heart in the foetus?

Answer 6

Right Ventricle – Pulmonary Artery (PA) - Patent Ductus Arteriosus (PDA) – Aorta

(bypasses the lungs)

Question 7

What are normal O2 sats in the foetus?

Answer 7

60-70%

Question 8

What does the ductus arteriorus do?

Answer 8

Protects lungs against circulatory overload
Allows the right ventricle to strengthen
Carries low oxygen saturated blood

Question 9

What does the ductus venous do?

Answer 9

Foetal blood vessel connecting the umbilical vein to the IVC
Blood flow regulated via sphincter
Carries mostly oxygenated blood

Question 10

What is the normal heart rate for a newborn?

Answer 10

120-160 bpm

Tachycardia - >160 bpm

Bardycardia - < 100 bpm

Question 11

What is the normal resp rate in the newborn?

Answer 11

30-60 /min

Periodical

Question 12

What is the normal BP in the newborn?

Answer 12

1 hr - 70/44
1 day - 70±9/42±12
3 days - 77±12/49±10

Question 13

How do babies thermoregulate?

Answer 13

Maternal thermoregulation in the womb
Newborn babies lack shivering thermogenesis thus need a metabolic production of the heat
Brown fat well innervated by sympathetic neurones so cold stress leads to lipolysis and heat production

BABIES DO NOT SHIVER

Question 14

What does cold stress lead to?

Answer 14

lipolysis and heat production of brown fat

Question 15

In what 4 ways do babies lose heat?

Answer 15

Radiation:
Heat dissipated to colder objects.

Convection:
Heat loss by moving air.

Evaporation:
We are born in water.

Conduction:
Heat loss to surface on which baby lies.

Question 16

How might you assess newborn breathing non-invasively?

Answer 16

Blood gas determination - PaCO2 5-6 kPa, PaO2 8-12 kPa

Trans-cutaneous pCO2/O2 measurement

Question 17

How might you assess newborn breathing invasively?

Answer 17

Capnography
Tidal volume 4-6 ml/kg
Minute ventilation: 
Tidal Volume ml/kg x respiratory rate
Flow-volume loop.

Question 18

When does physiological jaundice appear?

Answer 18

Day 2-3

Question 19

When does physiological jaundice disappear?

Answer 19

Within 7-10 DOL in term infants and up to 21 DOL in premature infants

Question 20

How does blue light prevent kernicterus?

Answer 20

Blue light converts bilirubin to water soluble form and increases oxidation of bilirubin.

Question 21

Why is it normal for a baby to have a weight loss of 10%?

Answer 21

Shift of interstitial fluid to intravascular

Diuresis

Question 22

For how long is it normal for a baby not to pass urine?

Answer 22

First 24 hours

Question 23

How well do full-term babies manage fluid/electrolyte balance?

Answer 23

Well

Question 24

Why do premature infants not manage fluids so well?

Answer 24

Less fat in body composition

Increased loss through kidney:

• Slower GFR
• Reduced Na reabsorption
• Decreased ability to concentrate or dilute urine

Increased Insensible Water Loss (IWL)

• Via immature skin and breathing
• Physiological IWL is 20-40 ml/kg/day but could be up to 82 ml/kg/day in 750-1000 g

Question 25

How do infant weight losses compare depending on term?

Answer 25

Physiological IWL is 20-40 ml/kg/day but could be up to 82 ml/kg/day in 750-1000 g

Question 26

What is normal temperature in the newborn?

Answer 26

Same as adult

Question 27

What are the ranges for blood gases in the newborn?

Answer 27

PaCO2 5-6 kPa, PaO2 8-12

Question 28

How does RBC production compare on DOL 7 with that in the uterus?

Answer 28

About 1/10 of the production

Question 29

How may a baby’s haemoglobin levels change over time?

Answer 29

Born with - Hb 15-20 g/l
Week 10 - Hb 11.4 g/l
Increase production of Erythropoetin
Week 20 - Hb 12.0 g/l

Question 30

What are the causes of anaemia of prematurity?

Answer 30

Reduced erythropoesis

Blood letting – most important cause! (iatrogenic)