Perinatal Adaptation Flashcards
what things must be given attention in perinatal period?
foetal circulation preparation for birth cardio adaptation glucose and temp homeostasis early nutrition and growth haematology and jaundice
function of placenta?
fetal homeostasis gas exchange nutrient transport to fetus wast product transport from fetus acid base balance hormone production transport of IgG
what are the 3 shunts in fetal circulation?
ductus venosus
foramen ovale
ductus arteriosus
describe the path of oxygenated blood in the fetus?
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
path of deoxygenated blood?
umbilical arteries branch off foetal aorta around the bladder and carry deoxygenated blood out of the baby via the umbilical cord to the placenta
what preparations for birth take place in 3rd trimester?
implication in pre-term baby?
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)
what preparations for birth occur at time of labour and delivery?
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)
what happens to the other 70ml of lung fluid?
has to be absorbed by baby
- crying helps absorb it into lymphatics
normal first few seconds after birth?
blue
starts to breathe cries
gradually goes pink
cord cut
what circulatory changes occur after birth?
pulmonary vascular resistance drops systemic vascular resistance rises oxygen tension rises circulating prostaglandins drop duct constricts foramen ovale closes
effects of duct constriction?
increased pO2
reduced blood flow
reduced prostaglandins
what happens to the fetal shunts?
foramen ovale = closes or persists as PFO in 10%
ductus arteriosus = becomes ligamentum arteriosus or persistent ductus arteriosis
ductus venosus = becomes ligamentum teres
what can happen if alveoli/lungs dont open and and ducts dont close?
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
how can duct closure be measured?
pre and post ductal saturation monitoring
- right hand = pre-ductal
- left foot = post-ductal
- anything >3% of difference indicates PPHN
how is PPHN managed?
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)
what is TTN?
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
management of TTN?
generally self resolves
may have an infection screen
important factors in first few hours of life?
thermoregualtion
glucose homeostasis
nutrition
why does heat loss occur in newborn and how?
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)
why is being cold dangerous in babies?
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
goal temp in baby?
36.5 - 37.5
why do pre-term babies get cold quicker?
low stores of brown fat
little S/C fat
larger surface area:volume ratio
how can hypothermia be prevented?
dry skin put a hat on skin to skin contact blanket/clothes heated mattress incubator
problems in glucose homeostasis in newborn?
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
causes of hypoglycaemia?
increased energy demands low glycogen stores - (small/premature) inadequate insulin:glucagon ratio - maternal diabetes - hyperinsulinism some drugs
composition changes in breastmilk?
colostrum
foremilk and hindmilk
benefits of breastfeeding?
helps prevent post-natal depression due to hormones released reduced breast cancer risk bonding cheaper adapts to babies needs
features of foetal haemoglobin?
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
features of adult haemoglobin?
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
why are most babies slightly anaemic after a few weeks?
foetal Hb broken down before adult Hb fullt synthesised
why does unconjugated jaundice occur in babies?
liver enzyme pathways present but immature
- breakdown of foetal haemoglobin
- conjugating pathways immature
- rise in circulating unconjugated bilirubin
is jaundice harmful in babies?
generally not unless very high levels
- can settle in brain/basal ganglia and cause damage/cerebral palsy
early or prolonged jaundice may be pathological
risk factors for adaptation problems after birth?
hypoxia/asphyxia in delivery small or large babies premature some maternal illnesses and medications ill baby (sepsis, congenital anomalies etc)