Perinatal Adaptation Flashcards
what is the function of the placenta
fetal homeostasis gas exchange nutrient transport to fetus waste product transport from fetus acid base balance hormone production transport of IgG
what are the three shunts involved in the fetal circulation
Ductus venous
Foramen ovale
Ductus arteriosus
(only 7% of fetal blood goes to the lungs bc obvs doesn’t need to if they’re not working yet)
where is the foramen oval
between the right and left atria
where is the ductus arteriosus
connects the pulmonary artery trunk and the arch of the aorta
(can be closed by prostaglandins)
where is the ductus venous
connecting the umbilical vein and the inferior vena cava so that oxygenated blood from the placenta can get pumped around the body
what preparation for birth occurs in the fetus in the third trimester
surfactant production
accumulation of glycogen in liver, muscle and heart
accumulation of brown fat (between scapulae and around internal organs)
accumulation of subcutaneous fat
swallowing amniotic fluid
what preparation for birth occurs in the fetus during labour and delivery
onset of labour increases catecholamines and cortisol
synthesis of lung fluid stops
during Vaginal Delivery - lungs are squeezed together (helps with getting rid of fluid)
what happens to the baby in the first seconds after birth
blue starts to breath cries gradually goes pink cord is cut
what causes the transition of the fetal circulation to the baby’s circulation
pulmonary vascular resistance drops
systemic vascular resistance increases (making blood go to the lungs instead)
oxygen tension rises
circulating prostaglandins drop
ductus arteriosus constricts
foramen vale closes
what causes the constriction of the ductus arteriosus
increases pO2
decreased blood flow
decreased prostaglandins
what happens to the foramen ovale after birth
closes or persists as PFO in 10%
what happens to ductus arteriosus after birth
Becomes ligament arteriosus
OR
PDA (persistent ductus arteriosus)
What happens to the ductus venous after brith
becomes ligamentum teres
what is persistent pulmonary hypertension of the newborn
failure of cardiorespiratory adaptation in the new born
how do you manage PPHN
ventilation oxygen nitric oxide sedation inotropes Extra corpeal membrane oxygenation
what is transient tachypnoea of the newborn
impaired lung function as fetal lung fluid has not been cleared properly
usually goes away without treatment in a few days
why do newborn babies loose heat so easily
they have a large surface area to volume ratio
wet when born
they can’t shiver
what are the 4 methods of heat loss in babies
conduction (through contact surfaces)
Convection (movement of air)
Evaporation (born wet)
Radiation
how do babies regulate their temperature
heat is produced by breakdown of stored brown adipose tissue in response to catecholamines
(this is not efficient in the first 12 hours of life )
peripheral vasoconstriction
why are small for dates/ preterm babies at higher risk of hypothermia
low stores of brown fat
little subcutaneous fat
larger surface area to volume ratio
how do you prevent hypothermia in a new born
get them dry put on a hat skin to skin contact blanket/clothes heated mattress incubator
how is glucose homeostasis maintained in the newborn
no longer get glucose supply from placenta and aren’t taking in much milk so:
drop in insulin
mobilisation of hepatic glycogen stores for gluconeogenesis
ability to use ketones as brain fuel
what causes hypoglycaemia
increased energy demands (eg. unwell or hypothermia)
low glycogen stores (eg. if premature)
maternal diabetes
hyperinsulinism (some drugs)
how do you avoid/treat hypoglycaemia in babies
identify those at risk
feed effectively
keep warm
monitor
how does the mother know to keep producing breast milk
baby starts to suckle (rooting and suck reflex)
feedback loop causes increase in supply (oxytocin and prolactin released)
composition of the milk changes as the baby gets bigger
- colostrum
- foremilk and hindmilk
what hormone is responsible for milk production
prolactin
what hormone is responsible for milk ejection
oxytocin
what happens to haemoglobin when the fetus becomes a baby
an increase in 2,3 BPG shifts the oxygen saturation curve to the right
this causes haematopoeisis to move to town marrow and Hb is synthesised more slowly and broken down
physiological anaemia occurs
Hb is at its lowest point at 8-10 weeks
why do babies get jaundice
Liver enzyme pathways are immature
physiological jaundice
early or prolonged jaundice my be pathological
what is physiological jaundice
breakdown of fetal haemoglobin
conjugating pathways are immature
rise in circulating unconjugaed bilirubin
this is generally not harmful unless very high levels
how do you treat a baby with physiological jaundice
blue light phototherapy
if v bad - exchange transfusion
what babies are at higher risk of adaptation problems
hypoxia/asphyxia during delivery
particularly small or large babies
some maternal illnesses and medications
if baby is ill - sepsis, congenital anomalies
