Perinatal Adaptation

Question 1

What are the functions of the placenta?

Answer 1

Foetal homeostasis
Gas exchange
Nutrition transport
Waste product transport
Acid-base balance
Hormone production
Transport of IgG

Question 2

What does the placenta ultimately prepare the baby for?

Answer 2

Delivery

Question 3

What are the three shunts present in the foetal circulation?

Answer 3

Ductus venosus, foramen ovale, ductus arteriosus

Question 4

What should happen to all three shunts in the foetal circulation after the baby is born?

Answer 4

They should close

Question 5

How much of the foetal output goes to the lungs?

Answer 5

Only 7%

Question 6

What shunt does oxygenated blood pass through when it is passing from the liver to the heart?

Answer 6

Ductus venosus

Question 7

What does the foramen ovale allow?

Answer 7

Allows blood to pass from the right ventricle to the left ventricle

Question 8

Why does very little blood go to the right ventricle in the foetal circulation?

Answer 8

The lungs are not fully developed yet so blood is not oxygenated there

Question 9

What shunt does blood pass through when going to the foetal lungs?

Answer 9

The ductus arteriosus

Question 10

Why is the foetus in a more hypoxic state than the delivered baby?

Answer 10

Oxygenated and deoxygenated blood is mixed in the foetal circulation

Question 11

How does the baby prepare for being born during the third trimester?

Answer 11

Produces surfactant
Accumulates subcutaneous fat, glycogen and brown fat
Swallowing amniotic fluid

Question 12

Where does brown fat accumulate in a baby?

Answer 12

Between the scapulae and around the internal organs

Question 13

What purpose does swallowing the amniotic fluid serve?

Answer 13

Helps to grow and expand the lungs

Question 14

What occurs in the foetus during the onset of labour?

Answer 14

There are increased catecholamines and cortisol

Question 15

When does synthesis of fluid stop in the foetus?

Answer 15

Once labour has commenced and the baby is being delivered

Question 16

How does vaginal delivery help the lungs adapt?

Answer 16

Squeezes the lungs = gets rid of 30% of 100ml lung content

Question 17

How does the baby get rid of 70% of the fluid in its lungs after it is born?

Answer 17

By crying

Question 18

What does a baby do in the first seconds after it is born?

Answer 18

Baby is blue, starts to breathe, begins to cry, gradually turns pink, cord is cut (usually delayed for 1 min)

Question 19

What happens to vascular resistance once the baby is born?

Answer 19

Pulmonary vascular resistance drops and systemic vascular resistance rises

Question 20

What circulatory changes occur once a baby is born?

Answer 20

Circulating prostaglandins drop

Duct constricts and foramen ovale closes

Question 21

What causes the foetal ducts to closes after birth?

Answer 21

pO2 increases

Flow and prostaglandins decrease

Question 22

What happens to the foetal shunts after birth?

Answer 22

Foramen ovale = closes or persists (10%)
Ductus arteriosus = become ligamentum arteriosus (rarely persists)
Ductus venosus = becomes ligamentum teres

Question 23

What can cause the failure of cardiopulmonary adaption?

Answer 23

Non-functioning placenta = alters acid-base balance
Prematurity
Sepsis
Prolonged hypoxic state

Question 24

What is the underlying reason for persistent pulmonary hypertension of the newborn?

Answer 24

Failure of the cardiopulmonary adaption

Question 25

Why can persistent pulmonary hypertension of the newborn be life-threatening?

Answer 25

Lungs are unable to inflate so have high pressure which prevents the oxygenation of blood

Question 26

Why does mixing of deoxygenated and oxygenated blood occur in persistent pulmonary hypertension of the newborn?

Answer 26

Foetal shunts don't close as systemic vascular pressure is lower than pulmonary vascular pressure

Question 27

What is used to diagnose persistent pulmonary hypertension of the newborn?

Answer 27

Pre-imposed ductal saturation monitoring = difference of more than 3% is diagnostic

Question 28

How is pre-imposed ductal saturation monitoring carried out?

Answer 28

Probe put on right hand (measures pre-ductal saturation) and another put on left foot (measures post-ductal saturation)

Question 29

How is persistent pulmonary hypertension of the newborn treated?

Answer 29

Ventilation, oxygen, nitric oxide (must be careful not to over-correct), sedation, inotropes, ECLS

Question 30

What are some features of transient tachypnoea?

Answer 30

Common, usually diagnosis of exclusion, resolves quickly, baby may grunt and usually gets infection screening

Question 31

What causes transient tachypnoea?

Answer 31

Usually occurs in big healthy babies born by section = no vaginal squeeze to empty fluid from lungs

Question 32

What are some factors that contribute to a baby's ability to thermoregulate?

Answer 32

Large surface area = babies proportionally have large head Wet when born Unable to shiver Peripheral vasoconstriction

Question 33

What are the four ways heat can be lost?

Answer 33

Evaporation, conduction, convection, radiation

Question 34

What is the main way babies produce heat?

Answer 34

Non-shivering thermogenesis = heat produced by breakdown of brown fat in response to catecholamines

Question 35

What is the main issue with using non-shivering thermogenesis as main way to produce heat?

Answer 35

Process isn't effective in first 12hrs of life

Question 36

What temperature should babies be kept between?

Answer 36

36.5-37.5 degrees

Question 37

Why is hypothermia common in premature and small full term babies?

Answer 37

They have low stores of brown fat, little subcutaneous fat and a larger surface area:volume ratio

Question 38

How may hypothermia be prevented?

Answer 38

Dry the baby, put on a hat, skin to skin contact (best option), blanket/clothes, heated mattress, incubator

Question 39

What happens to the baby's glucose homeostasis once it is born?

Answer 39

Interruption to glucose supply from placenta and very little oral intake of milk = drop in insulin and increase in glycogen

Question 40

How do babies control their glucose homeostasis?

Answer 40

Mobilisation of hepatic glycogen stores for gluconeogenesis | Able to use ketones as brain fuel

Question 41

How may hypoglycaemia arise in a baby?

Answer 41

Increased energy demands = unwell, hypothermia Low glycogen stores = small baby, premature Inappropriate insulin:glucagon ratio = maternal diabetes, hyperinsulinaemia (usually transient) Some drugs = beta blockers

Question 42

What is the aim of the UNICEF Baby Friendly Initiative?

Answer 42

Help promote and support breastfeeding

Question 43

What occurs during breastfeeding?

Answer 43

Baby starts to suckle = rooting and suck reflex Feedback loop causes increase in supply Composition changes = colostrum, foremilk, hindmilk

Question 44

What are some benefits of breastfeeding?

Answer 44

Prevents cancer and post-natal depression Cheaper and easier than bottle feeding Helps with bonding

Question 45

How much weight are babies expected to lose after their are born?

Answer 45

About 10% of their birth weight

Question 46

Why does foetal haemoglobin become disadvantageous?

Answer 46

Has high affinity for oxygen but doesn't release it easily to tissues

Question 47

What shifts the oxygen dissociation curve to the right in babies once they are born?

Answer 47

Increase in 2,3 BPG

Question 48

What impact does the slower synthesis of adult haemoglobin have?

Answer 48

Causes physiological anaemia in babies between 8-10 weeks (reticulocyte count should be checked to ensure this isn't any underlying pathology)

Question 49

Where does haematopoiesis move to once the baby is born?

Answer 49

From the liver to the bone marrow

Question 50

What causes physiological jaundice in babies?

Answer 50

Liver enzymes present but immature = only harmful if high levels of unconjugated bilirubin

Question 51

How does jaundice arise in babies?

Answer 51

Foetal haemoglobin is broken down but conjugation pathways are immature = rise in unconjugated bilirubin

Question 52

When may jaundice in babies be pathological?

Answer 52

If it is prolonged or has an early onset

Question 53

How is jaundice treated in babies?

Answer 53

Phototherapy or exchange transfusion (only if severe)

Question 54

Why is unconjugated bilirubin harmful in babies?

Answer 54

May cross BBB and settle in basal ganglia = causes cerebral palsy in later life

Question 55

How is phototherapy used to treat jaundice in babies

Answer 55

Blue light used to change unconjugated bilirubin to excretable form and babies then pee it out

Question 56

What are the risk factors for adaption problems in a foetus?

Answer 56

``` Hypoxia or asphyxia during delivery Very small/large babies Prematurity Maternal illness or medications Ill babies (sepsis, congenital abnormalities) ```