Neonates Flashcards
what are the 3 shunts in the cardio system of feotuses that close over after birth
where are each
foramen ovale - between the RA and LA, allows blood to travel form RA directly to LA = more oxygenised
ductus arteriosum - between pulmonary artery and arch of aorta
ductus venosus - in the liver
apart from the 3 shunts, why doesn’t much blood go to the lungs
why is this
high resistance in pulmonary system
theres no need to go to lungs bc not getting any oxygen there (oxygen comes from placenta)
what happens to the shunts present in fetuses in the 3rd trimester
they close over
at what age does a fetus start producing surfactant
clinical significance of this
24w, becomes sufficient at 36w
if premature <36w, not enough surfactant = risk of ARDS = need steroids
normal gestation (weeks)
37-42w
normal weight
2.5-4kg
what is normal weight gain/loss in first 10 days
10% weight loss = NORMAL
initial O2 sats of baby
O2 sats of baby after 10 mins
60%
>90% by 10 mins
why do babies cry when they first come out
causes alveolar expansion and increase intrathoracic pressure = max air into lungs
what is in the lungs when inside mum
how does crying change this
fluid inside lungs when inside mum
crying = increased intrathoracic pressure = pushes fluid into interstitial spaces = reabsorbed in lymph
when do you cut the babies cord
after it stops pulsating (10 mins)
what causes foramen ovale closure when out the womb
what is the result if this doesn’t happen
increased systemic vascular resistance = increased pressure into RA = closes foramen ovale
persistent foramen ovale
what causes ductus arteriosus to close when out of the womb
what is the result if this doesn’t happen
decreased pulmonary pressure (compared to inside womb) = persistent ductus arteriosus
patent ductus arteriosus
what causes the ductus venosus in the liver to close
what structure does this result in
systemic vascular pressure increase
becomes the ligamentum teres
what happens to prostaglandin when outside womb, what does this do to the circulatory ducts
prostaglandin drops (produced by placenta) = closes ducts
why are babies often cold when they come out the womb
by what mechanism do they overcome this
large SA
wet
cant shiver (immature hypothalamus and muscles)
overcome this by non shivering thermogenesis
what is non shivering thermogenesis
breakdown of brown fat = increase body temp in neonates
which group of babies are even worse at maintaining temp than normal babies (hence need extra help)
preterm or SGA babies
why does physiological aneamia occur
change from fetal haemoglobin to adult haemoglobin (gamma to beta)
but adult haemoglobin takes longer to be made than fetal haemoglobin takes to be destroyed
= physiological anaemia
what does apgar score stand for
when is it done
1, 5, 10 mins after birth
should gradually increase to 10
Appearance Pulse Grimace (reflex) Activity (muscle tone) Respiration
everything out of 2
definition of preterm (in weeks)
24w-36w and 6 days
causes of preterm
multiple births infection placental abruption pre-eclampsia/eclampsia mum teenager or >40yo
post delivery care of preterm babies
warmth - plastic bag, hat, skin to skin
steroids - to reduce risk of ARDS
delay cord clamping - to increase Hb going into baby
how should preterm babies be delivered
c section (emergency or planned)
