Foetal shunts Flashcards
What are the three foetal shunts
- Ductus Venosus
- Foramen ovale
- Ductus arteriosus
How does fetal circulation happen
- Umbilical vein carries oxygenated blood
2.Blood bypasses liver via the ductus Venosus - Blood enters heart via the right atrium and shunts through foramen ovale to bypass the lungs
4.Blood shunts across the patent ductus arteriosus from the pulmonary artery to the aorta
5.Blood carrying the waste products and CO2 can flow back to the placenta via the umbilical arteries.
What happens to the foramen ovale during birth
First breath causes lungs to expand and fluid to be pushed out of alveoli.
Pulmonary pressures decrease and systemic blood pressure increases
Pressure in the right side of heart decreases which causes the foramen ovale to shut.
what happends to the Ductus Venosus and Ductus arteriosus at birth
Umbilical cord clamped, Ductus venosus degenerates into the liagmentum venosum.
Lack of prostaglandin from mother and increased oxygen stimulates the closure of the ductus arteriosus.
What is prostaglandin
Can also be called prostin
Natural relaxant which keeps the ductus arteriosus patent.
What happens when a patient is diagnosed with Transposition of the great arteries?
The pulmonary artery and aorta get switched.
So deoxygenated blood goes to the body and oxygenated blood to the heart.
How does prostaglandin help with someone who is diagnosed with TOGA
Prostin dilates the ductus arteriousus and prevents it from closing. This allows some oxygenated blood to the delievered to the body.
Side effects of Prostin
Can alter systemic and pulmonary pressure and resistance.
So nurses have to:
* Manage ABCD
* Sats between 75-85%
* Pre/post ductal sats
* Monitor pulses and BPs in all four limbs
what are pre and post ductal saturations
Babies with congenital heart disease may have more normal saturations in the hands than in the feet. All babies require oxygen saturation measurement in the right upper limb (pre- ductal) and the right foot (post-ductal).
