Fetal Circulation Flashcards Preview

Neonatal Pathophysiology > Fetal Circulation > Flashcards

Flashcards in Fetal Circulation Deck (168)
Loading flashcards...
1

What are unique structures to fetal circulation?

1) placenta
2) umbilical arteries and veins
3) fetal shunts: ductus venosus, foramen ovale and ductus arteriosus

2

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

3

How many umbilical arteries are there?

2

4

What is the function of the umbilical arteries?

to carry Deoxygenated blood in utero

5

What is the reaction of arteries in a hypoxic environment?

vasoconstrict

6

How do umbilical arteries present in the cord?

muscular, smaller vessels

7

What is the range of PaO2 available in the umbilical arteries?

15-25%

8

What central line should be placed in an emergent situation if no vascular access is previously in place?

UVC, never arterial

9

What type of medications should never be run through an arterial line?

RX with vasocontricting effects: Epi, caffeine, insulin, dopamine, norepi

10

How many umbilical veins are there?

1

11

What is the function of the umbilical vein?

to carry oxygenated blood in utero

12

What is the range of PaO2 available in the umbilical vein?

32-35%

13

How does the umbilical vein present in the cord?

larger, thinner walled vessel

14

What is the ductus venous?

structure that allows blood to bypass the liver and empty into the IVC

15

When is closure of the ductus venous expected?

within the first week of life

16

What becomes of the ductus venous after anatomical closure?

eventually becomes the hypogastric ligament

17

What is the foramen ovale?

structure preferentially allows blood to flow from the RA into the LA

18

Where is the foramen ovale located?

in the central portion of the atrial septum

19

What mechanism facilitates the closure of the foramen ovale?

increasing LA pressure

20

When is anatomic closure of the FO achieved?

approximately 1 month

21

Where is the PDA?

connects the pulmonary artery and the aorta; can be a site of shunting especially in the preterm infant

22

What mechanism facilitates the closure of the PDA?

in response to readily available pO2

23

When is functional and anatomic closure of the PDA achieved?

functional: 2-4 dol; anatomic: during the next month

24

What becomes of the PDA after anatomical closure?

persists as the ductus ligament

25

What percentage of total cardiac output goes to the lungs in utero for tissue nourishment?

8-12%

26

What is the effect of acidosis on the vasculature?

vasoconstriction

27

Where is the site of greatest vascular resistance in fetal circulation?

PVR>SVR

28

Where is the site of O2/CO2 exchange in fetal circulation?

intervillous spaces; placenta is nourished from maternal venous system

29

Where is the site of greatest vascular resistance in postanatal circulation?

SVR>PVR

30

Where is the site of O2/CO2 exchange in postnatal circulation?

alveolus/capillary