Perinatal adaptation

Question 1

What is the function of the placenta?

Answer 1

• foetal homeostasis
• gas exchange
• nutrient transport to foetus
• waste product transport from foetus
• acid base balance
• hormone production
• transport of IgG

Question 2

What is the function of the foetal liver?

Answer 2

Produces albumin, clotting factors, RBCs

Question 3

What is the function of the foetal kidney?

Answer 3

Excretes urine, contributes to amniotic fluid

Question 4

What are the three shunts of the foetal circulation?

Answer 4

• ductus venosus
• foramen ovale
• ductus arteriosus

Question 5

What happens in the foetus in the 3rd trimester in preparation for birth?

Answer 5

• surfactant production
• accumulation of glycogen- liver, muscle, heart
• Accumulation of brown fat- between scapulae and around internal organs
• accumulation of SC fat
• swallowing amniotic fluid

Question 6

What happens during delivery to prepare the baby for life?

Answer 6

• onset of labour- increased catecholamines/cortisol
• synthesis of lung fluid stops
• vaginal delivery- squeezes lungs

Question 7

Describe circulatory transition

Answer 7

• Pulmonary vascular resistance drops
  
  • onset of breathing
  • rise in arterial pO2 from 2-3.5kPa to 9-13kPa
• Systemic vascular resistance rises
  
  • cord clamped
  • huge, low resistance vascular bed removed
• Oxygen tension rises
• Circulating prostaglandins drop
• Duct constricts
• Foramen ovale closes

Question 8

How does duct construction occur?

Answer 8

Decreased flow due to decreased pulmonary vascular resistance

Increased pO2- oxygen sensitive muscular layer

Decreased circulating PGE2 due to increased lung metabolism

Shunt becomes bidirectional then left to right

Physiological closure within first few hours/days

Anatomic closure within 7-10 days

Question 9

What happens to the ductus arteriosus

Answer 9

Closes and becomes ligamentum arteriosus

Question 10

What happens to the ductus venosus

Answer 10

Closes and becomes ligamentum teres

Question 11

what happens as a result of failure of cardiorespiratory adaptation?

Answer 11

Asphyxia- hypoxia/acidosis

Prematurity

Sepsis

Hypoxia

Cold stress

Question 12

What is PPHOTN

Answer 12

Persistent pulmonary hypertension of the newborn

Lung vascular resistance fails to fall

Shunts remain

Right to left flow at PFO

Right to left flow at PDA

Question 13

How does PPHN present?

Answer 13

Blue baby

big difference between pre and post ductal sats

Sick babies

Question 14

How should PPHN be managed?

Answer 14

• ventilation
• oxygen
• nitric oxide
• sedation
• inotropes
• ECLS

Question 15

What is key to the first few hours of life?

Answer 15

• thermoregulation
• glucose homeostasis
• nutrition

Question 16

What are the 4 mechanisms of heat loss?

Answer 16

• radiation
• convection
• conduction
• evaporation

Question 17

How do babies thermoregulate

Answer 17

• non-shivering thermogenesis
  
  • heat produced by breakdown of stored brown adipose tissue in response to catecholamines
  • not efficient in the first 12 hours of life
• peripheral vasoconstriction
• newborn babies need help

Question 18

Why are small for dates/preterm babies at risk of hypothermia?

Answer 18

Low stores of brown fat

Little subcutaneous fat

Larger surface area:volume

Question 19

How can hypothermia be prevented?

Answer 19

• dry baby
• wear hat
• skin to skin
• blanket/clothes
• heated mattress
• incubator

Question 20

Describe glucose homeostasis after birth

Answer 20

Interruption of glucose supply from the placenta

Very little oral intake of milk

Drop in insulin, increase in glycogen

Mobilisation of hepatic glycogen stores for gluconeogenesis

Ability to use ketones as brain fuel

Question 21

What causes babies to have increased energy demands?

Answer 21

Unwell

Hypothermia

Question 22

What causes babies to have Low glycogen stores?

Answer 22

Small/premature

Question 23

What causes babies to have inappropriate insulin/glucagon ratio?

Answer 23

Maternal diabetes

Hyperinsulinism

Question 24

How can low glucose levels be avoided?

Answer 24

Identifying those at risk

Feed effectively

Keep warm

Monitor

Question 25

What weight loss after birth is normal?

Answer 25

10% of body weight

Question 26

What is hypernatraemic dehydration?

Answer 26

It is a risk when some babies lose more than 10% of their body weight

Usually caused by delayed lactation

Question 27

When does foetal haemoglobin become disadvantageous?

Answer 27

After birth

There will be an increase in 2,3 BPG and curve will shift to right

Question 28

What happens after birth regarding Hb?

Answer 28

Haemoatopoesis moves to bone marrow

Adult Hb synthesised more slowly than Fetal Hb broken down

Physiological Anaemia

Question 29

What causes physiological jaundice of the newborn?

Answer 29

Breakdown of foetal haemoglobin

Conjugating pathways immature

Rise in circulating unconjugated bilirubin

Generally not harmful unless very high levels

Question 30

What are the risk factors for adaptation problems?

Answer 30

Hypoxia/asphyxia during delivery

Small or Large baby

Premature babies

Maternal illness/medication

Ill babies- sepsis, congenital anomaly