foetal circulation and adaption at birth Flashcards Preview

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Flashcards in foetal circulation and adaption at birth Deck (11)
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1
Q

what are the functions of placenta?

A
  • fetal homeostasis
  • gas exchange
  • acid base balance
  • nutrient transport to fetus
  • waste product transport from fetus
  • hormone production
  • transport of igG
  • PGE2
2
Q

what happens in the foetus?

A
  • lungs are filled and unexpanded
  • only 7% of RV output goes to lungs
  • liver has a small role
  • gut is not in use
3
Q

what are the 3 shunts?

A
  • ductus venosus
  • foramen ovale
  • ductus arteriosus
4
Q

what is the anatomy of the ductus venosus?

A
  • connects the umbilical vein to the inferior vena cava

- carries majority of placental blood into IVC, bypassing portal circulation

5
Q

what is the anatomy of the foramen ovale?

A
  • opening in atrial septum connecting RA to LA
6
Q

what is the anatomy of the ductus arteriosus?

A
  • connects pulmonary bifurcation to the descending aorta
7
Q

what is persistent pulmonary hypertension of the new-born (PPHN)?

A
  • when lung vascular resistance fails to fall
  • shunts remain = right to left flow at PFO, eight to left flow to PDA
  • results in blue baby
  • large difference between pre and post ductal O2 saturation
  • ventillation, oxygenation, high systemic blood pressure inhaled nitric oxide, ECLS
8
Q

what adaptions do new borns have?

A
  • decreased pulmonary vascular resistance

- increased systemic pulmonary vascular resistance

9
Q

how does the foramen ovale close?

A
  • as PVR falls and SVR rises, the LA pressure exceeds the RA pressure
  • the flap is pushed closed
10
Q

how does duct constriction occur?

A
  • decreased flow due to decrease pulmonary vascular resistance
  • increased pO2 - O2 sensitive muscular layer
  • decreased circulating PGE2 due to increased lung metabolism
  • shunt becomes bidirectional then left to right
  • physiological closure within first few hours / days
  • anatomic closure within 7-10 days
11
Q

what is duct dependent circulation?

A
  • caused by some congenital heart diseases
  • IV prostaglandin E2 can be used to keep the duct open until an alternative shunt established or definitive surgery carried out