The Newborn Infant Flashcards
(59 cards)
what structure allows foetal bood to bypass the liver, and what vessel does it join into
the ductus venosus
joints into the IVC - drains into RA of heart
what structures in the heart allow the blood to bypass the lungs
- the foramen ovale between the RA and LA allows blood to flow straight from RA to LA, then LV and out aorta
- if any blood escapes the FO and flows into RV and then out pulmonary artery, the patent ductus arteriosus will allow it to enter the aorta
by which gestational age does the foetus have lungs that function well enough (dont need steroids if delivered)
36 weeks
when does the baby start producing surfactant, and what does this do
from around 24 weeks, it reduces alveolar surface tension stopping the smaller alveoli from collapsing
how does vaginal delivery help lung preparation for the outside world
it squeezes the fluid out of the lungs
if eg C section, there will be delayed clearance of lung fluid and transient tachypnoea/resp distress
what are O2 sats expected to be when thebaby is born
they will intially be around 70% and will increase to around 90% over teh first 10 minutes
hwat colour is the baby when born
blue, turns pink as oxygenated
what changes happen in the lungs after birth
the lungs before were a very high pressure system (unfavourable.). PVR drops and SVR rises, driving blood through lungs
FO and DA close
what causes closure of teh FO, and what is left behind
the pressure in LA > RA - forcing FO shut
fossa ovalis remains
what kept the DA open in utero, and what now causes it to shut
it was kept open by the placental PG
after birth, there are no more PG and high O2 tension causes the smooth muscle in it’s walls to constrict
what is the closed DA called in children/adults
ligamentum arteriosum
what murmur would a PDA cause
machine like murmur below the left clavicle
how do you manage a PDA
IV NSAIDs - indomethacin or ibuprofen (anti COX action inhibits PG production and causes closure).
what does the ducuts venosus become
the ligamentum teres (round ligament) in the liver
why are neonates particularly prone to rapid heat loss
- covered in fluid when born
- have a high surface area : volume ratio
what are the 4 mechanisms by which neonate can lose heat
- radiation
- evaporation of fluid
- conductive - contact with cold surface
- convection - air flow
how do babies warm themselves up? they cant shiver
- non shivering thermogenesis
- stored brown fat breaks down in response to catecholamines - heat is generated through ATP
where is the brown fat found in babies
between scapula, around organs, sternum
does NST work immediately from birth?
no, takes around 12 hours
what are the negative consequences of hypothermia, and NST
it increases metabolic rate
- so uses a lot of O2 = resp rate increases to get more O2 = cant meet demands = anaerobic metabolism and hypoxia
- uses lots of glucose - depletes glycogen stores and results in hypoglycaemia
- hyopglycaemia leads to decreased surfactant proudction and pulmonary vasoconstriction - resp distress
- = HYPOXIA
what necessary precuations must be taken to keep baby warm
good delivery room temperature, dry baby immediately, swaddle (hat), skin to skin contact
what extra precuations must be taken for premature babies or to rewarm hypothermic babies
- put in polyethene bag
- blankets/clothes, heated mattress, prewarmed incubator
what is the normal weight range for a newborn baby
2.5-4kg
neonatal vital signs
- Resp rate: 40-60, signs of work of breathing may be attributable to circulatory adaptation
- HR: 120-140
- Cap refill: 2-3 seconds
- Colour: Pink/blue/white
- SaO2: Around 65-70% when born, increase to 90% in first 10 minutes
