Flashcards in Fetal Circulation Deck (168)
What are unique structures to fetal circulation?
2) umbilical arteries and veins
3) fetal shunts: ductus venosus, foramen ovale and ductus arteriosus
What are the functions of the placenta?
1) respiratory function- instead of lungs
2) metabolic function- instead of intestines
3) provides O2, nutrients and H20 to fetus
4) transfers CO2 and other wastes to MOB for elimination
How many umbilical arteries are there?
What is the function of the umbilical arteries?
to carry Deoxygenated blood in utero
What is the reaction of arteries in a hypoxic environment?
How do umbilical arteries present in the cord?
muscular, smaller vessels
What is the range of PaO2 available in the umbilical arteries?
What central line should be placed in an emergent situation if no vascular access is previously in place?
UVC, never arterial
What type of medications should never be run through an arterial line?
RX with vasocontricting effects: Epi, caffeine, insulin, dopamine, norepi
How many umbilical veins are there?
What is the function of the umbilical vein?
to carry oxygenated blood in utero
What is the range of PaO2 available in the umbilical vein?
How does the umbilical vein present in the cord?
larger, thinner walled vessel
What is the ductus venous?
structure that allows blood to bypass the liver and empty into the IVC
When is closure of the ductus venous expected?
within the first week of life
What becomes of the ductus venous after anatomical closure?
eventually becomes the hypogastric ligament
What is the foramen ovale?
structure preferentially allows blood to flow from the RA into the LA
Where is the foramen ovale located?
in the central portion of the atrial septum
What mechanism facilitates the closure of the foramen ovale?
increasing LA pressure
When is anatomic closure of the FO achieved?
approximately 1 month
Where is the PDA?
connects the pulmonary artery and the aorta; can be a site of shunting especially in the preterm infant
What mechanism facilitates the closure of the PDA?
in response to readily available pO2
When is functional and anatomic closure of the PDA achieved?
functional: 2-4 dol; anatomic: during the next month
What becomes of the PDA after anatomical closure?
persists as the ductus ligament
What percentage of total cardiac output goes to the lungs in utero for tissue nourishment?
What is the effect of acidosis on the vasculature?
Where is the site of greatest vascular resistance in fetal circulation?
Where is the site of O2/CO2 exchange in fetal circulation?
intervillous spaces; placenta is nourished from maternal venous system
Where is the site of greatest vascular resistance in postanatal circulation?