adaptation at birth Flashcards
what is the function of the placenta
maintain fetal homeostasis gas exchange nutrient transport to fetus waste product transport from fetus acid base balance hormone production transport of IgG
name the 3 shunts present in the fetal circulation
ductus venosus
foramen ovale
ductus arteriosus
what percentage of the fetal circulation goes via the lungs
7%
where is ductus venosus
go from the left umbilical vein to the IVC
where is the foramen ovale
in the septum between the left and right atria
where is ductus arteriosus
connects the pulmonary trunk to the proximal descending aorta
what physiological processes occur in the 3rd trimester in preparation of birth
surfactant production
accumulations of glycogen in liver, muscle and the heart
accumulation of brown fat between scapulae and around internal organs
accumulation of SC fat
swallowing amniotic fluid
describe the circulatory transition that occurs after birth
pulmonary vascular resistance drops systemic vascular resistance rises oxygen tension rises circulating prostaglandins drop ductus arteriosus constricts foramen ovale closes
what causes the duct constriction after birth
increased pO2
decreased flow
decreased prostaglandins
what happens to the shunts present in the fetal circulation
foramen ovale closes or persists as PFO
ductus arteriosus constricts to become ligament arteriosus or persists as PDA
ductus venosus constricts to become ligament teres
what causes persistent pulmonary hypertension of the newborn
persistence of the fetal circulation
management of PPHN
ventilation oxygen nitric oxide sedation inotropes ECLS (extra-corporeal life support)
what sign is indicative of PPHN
O2 sats in right hand are higher than left foot
what are the 4 methods of heat loss in a newborn
convection
conduction
evaporation
radiation
what is the main source of heat production in newborns
non shivering thermogenesis
heat produced by breakdown of stored brown adipose tissue in response to catecholamines
not efficient in the first 12 hours of life
(additional peripheral vasoconstriction)
why are preterm/SGA babies more prone to hypothermia
low stores of brown fat
little SC fat
larger surface area:volume
how to prevent hypothermia
keep baby dry hat skin to skin blanket/clothes heated mattress incubator
what changes in glucose homeostasis occur after birth
interruption of glucose supply from placenta
very little oral intake of milk
drop in insulin, increase in glycogen
mobilisation of hepatic glycogen stores for gluconeogeneis
what metabolites are babies able to use as brain fuel
ketones
what can cause hypoglycaemia in a newborn
increased energy demands (unwell/hypothermia)
low glycogen stores (small/premature)
inappropriate insulin:glucagon ratio (maternal DM, hyperinsulinism)
which hormones are responsible for milk production and ejection
production = prolactin ejection = oxytocin
what causes physiological anaemia in newborns
adult Hb is synthesised more slowly than fetal Hb is broken down
what causes physiological jaundice
liver enzyme pathways are present but immature
breakdown of fetal Hb
conjugating pathways are immature
rise in circulating unconjugated bilirubin
when might jaundice be pathological in newborns
early (<24 hours) or prolonged jaundice may be pathological
what are risk factors for adaptation problems
hypoxia/asphyxia during delivery particularly small or large babies premature babies some maternal illness and medications ill babies (sepsis, congenital anomalies)
