Perinatal Adaptation

Question 1

what things must be given attention in perinatal period?

Answer 1

foetal circulation
preparation for birth
cardio adaptation
glucose and temp homeostasis
early nutrition and growth
haematology and jaundice

Question 2

function of placenta?

Answer 2

fetal homeostasis
gas exchange
nutrient transport to fetus
wast product transport from fetus
acid base balance
hormone production
transport of IgG

Question 3

what are the 3 shunts in fetal circulation?

Answer 3

ductus venosus
foramen ovale
ductus arteriosus

Question 4

describe the path of oxygenated blood in the fetus?

Answer 4

from mum via umbilical vein
through liver via ductus venosus into the IVC and into the right atrium
passes through foramen ovale into the left atrium then on to rest of body via aorta
around 7% doesnt go through foramen ovale and goes into right ventricle instead, then passes through ductus arteriosus in pulmonary artery towards lungs

Question 5

path of deoxygenated blood?

Answer 5

umbilical arteries branch off foetal aorta around the bladder and carry deoxygenated blood out of the baby via the umbilical cord to the placenta

Question 6

what preparations for birth take place in 3rd trimester?

implication in pre-term baby?

Answer 6

surfactant production
accumulation of glycogen (liver, muscle, heart)
accumulation of brown fat (like insulating fat - between scapulae and around internal organs)
accumulation of S/C fat (more insulation)
swallowing and inhaling amniotic fluid (fills lungs and helps them grow)
(all these things will need supported in pre-term baby)

Question 7

what preparations for birth occur at time of labour and delivery?

Answer 7

onset of labour = increased catecholamines/cortisol
synthesis of lung fluid stops
vaginal delivery squeezes lungs to try and squeeze out some lung fluid (only 30ml of the 100ml present is expelled)

Question 8

what happens to the other 70ml of lung fluid?

Answer 8

has to be absorbed by baby

- crying helps absorb it into lymphatics

Question 9

normal first few seconds after birth?

Answer 9

blue
starts to breathe cries
gradually goes pink
cord cut

Question 10

what circulatory changes occur after birth?

Answer 10

pulmonary vascular resistance drops
systemic vascular resistance rises
oxygen tension rises
circulating prostaglandins drop
duct constricts 
foramen ovale closes

Question 11

effects of duct constriction?

Answer 11

increased pO2
reduced blood flow
reduced prostaglandins

Question 12

what happens to the fetal shunts?

Answer 12

foramen ovale = closes or persists as PFO in 10%
ductus arteriosus = becomes ligamentum arteriosus or persistent ductus arteriosis
ductus venosus = becomes ligamentum teres

Question 13

what can happen if alveoli/lungs dont open and and ducts dont close?

Answer 13

persistent pulmonary hypertension of the newborn - AKA PPHN (persistence of foetal circulation)
- can be due to lack of surfactant
blood doesnt get oxygenated in the lungs and ducts are still open so even if some blood is oxygenated it mixes with the deoxygenated

Question 14

how can duct closure be measured?

Answer 14

pre and post ductal saturation monitoring

• right hand = pre-ductal
• left foot = post-ductal
• anything >3% of difference indicates PPHN

Question 15

how is PPHN managed?

Answer 15

ventilation
oxygen
nitric oxide (vasodilates pulmonary vasculature)
sedation (to prevent them trying to breathe against the ventilator)
inotropes
ECLS/ECMO (very invasive, big risks but can be life savnig)

Question 16

what is TTN?

Answer 16

transient tachypnoea of newborn
typically in big term babies born via C section
baby takes longer to absorb the fluid
can sound a bit grunty and have streaky appearance on CXR

Question 17

management of TTN?

Answer 17

generally self resolves

may have an infection screen

Question 18

important factors in first few hours of life?

Answer 18

thermoregualtion
glucose homeostasis
nutrition

Question 19

why does heat loss occur in newborn and how?

Answer 19

baby head is very large by comparison to body to large surface area to loose heat from
wet when born which can cause them to be cold
methods
- radiation
- convection (Draft passing over wet skin etc)
evaporation (evaporation of liquid)
conduction (heat conducted onto whatever surface theyre on)

Question 20

why is being cold dangerous in babies?

Answer 20

theyre not able to shiver
main source of heat production is non-shivering thermogenesis where heat is produced by breakdown of stored brown fat in response to catecholamines but this doesnt work in first 12 hrs of life

Question 21

goal temp in baby?

Answer 21

36.5 - 37.5

Question 22

why do pre-term babies get cold quicker?

Answer 22

low stores of brown fat
little S/C fat
larger surface area:volume ratio

Question 23

how can hypothermia be prevented?

Answer 23

dry skin
put a hat on
skin to skin contact
blanket/clothes
heated mattress
incubator

Question 24

problems in glucose homeostasis in newborn?

Answer 24

interruption of glucose supply from placenta and very little oral intake of milk for first few days
therefore a drop in insulin and increase in glycogen occurs
mobilisation of hepatic glycogen stores for gluconeogenesis occurs and babies are able to use ketones as brain fuel

Question 25

causes of hypoglycaemia?

Answer 25

increased energy demands
low glycogen stores
- (small/premature)
inadequate insulin:glucagon ratio
- maternal diabetes
- hyperinsulinism
some drugs

Question 26

composition changes in breastmilk?

Answer 26

colostrum

foremilk and hindmilk

Question 27

benefits of breastfeeding?

Answer 27

helps prevent post-natal depression due to hormones released
reduced breast cancer risk
bonding
cheaper 
adapts to babies needs

Question 28

features of foetal haemoglobin?

Answer 28

higher affinity for oxygen (better at picking it up but not as good at letting it go into the tissues)
breaks down faster
made in the liver

Question 29

features of adult haemoglobin?

Answer 29

made in bone marrow
more easily lets go of oxygen
- due to increased 2, 3 BPG (shifts curve to the right)
synthesised slower than foetal

Question 30

why are most babies slightly anaemic after a few weeks?

Answer 30

foetal Hb broken down before adult Hb fullt synthesised

Question 31

why does unconjugated jaundice occur in babies?

Answer 31

liver enzyme pathways present but immature

• breakdown of foetal haemoglobin
• conjugating pathways immature
• rise in circulating unconjugated bilirubin

Question 32

is jaundice harmful in babies?

Answer 32

generally not unless very high levels
- can settle in brain/basal ganglia and cause damage/cerebral palsy
early or prolonged jaundice may be pathological

Question 33

risk factors for adaptation problems after birth?

Answer 33

hypoxia/asphyxia in delivery
small or large babies
premature 
some maternal illnesses and medications
ill baby (sepsis, congenital anomalies etc)