5 fetal adaptations
What vessel carries oxygenated blood to the fetus?
Umbilical vein
Are fetal lungs high or low resistance?
High resistance
What happens to systemic resistance after cord clamping?
It increases
What happens to pulmonary resistance after first breath?
It decreases
If PDA remains open after birth, what type of shunt occurs?
L to R
What vessel carries deoxygenated blood back to the placenta?
Umbilical arteries
Which side of the heart has higher pressure before birth?
Right side
What causes umbilical vessels to constrict?
Cold exposure and increase oxygen
What happens to left atrial pressure after birth?
It increases
If foramen ovale remains open later in life, what risk increases?
Stroke
What structure bypasses the liver?
Ductus venosus
Why does blood flow right to left before birth?
Right sided pressure is higher
What closes d/t blood no longer flowing through the umbilical cord?
Ductus venosus
What pressure change closes the foramen ovale?
LA pressure > RA pressure
If a newborn becomes cyanotic when PDA closes, what should you suspect?
Duct-dependent heart defect
What structure connects the RA & LA?
Foramen ovale
Why doesn't blood want to go to the fetal lungs?
They are fluid filled with high resistance - blood will always take the least resistance path
What eventually happens to fetal shunts after closure?
They become ligaments
What two factors close the ductus arteriosus?
Increased oxygen and decreased prostaglandins
What medication is given to keep PDA open in critical CHDs?
Prostaglandins
*Prostaglandins PROP open ductus arteriosus*
What structure connects the pulmonary artery to the aorta?
Ductus arteriosus
Where does oxygen exchange occur before birth?
Placenta
How long does it take for umbilical arteries to close?
minutes to hours
How long until ductus arteriosus functionally closes?
Within hours to 1-2 days
What major physiological "flip" occurs at birth?
Pulmonary resistance decreases and left sided pressure becomes higher than the right