3. Physiology
3.8. Maternal and foetal

foetal circulation

 

 

 

 

Before birth

Umbilical vessels

Umbilical vein x 1

Umbilical arteries x 2

 

 

 

Maternal and foetal

Uterine

Uterine flow = 600mL/min

Maternal [Hb] = 120g/L

p50 = 26.6mmHg

NB:

Uterine blood flow = 500-750mL/min

85% of uterine blood flow goes to placenta

Foetal capillaries

Umbilical flow = 300mL/min

Foetal [Hb] = 170g/L

p50 = 18-20mmHg

Umbilical artery

pO2 = 18mmHg

Umbilical vein

pO2 = 28mmHg

 

 

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[KB2:p251]

Respiratory parameters: Neonate vs adult

 

Neonate vs adult
Neonate Adult units
Dead space 2.2 2.2 mL/kg
Tidal volume 7 7 mL/kg
Vd/Vt 0.3 0.3 mL/kg
Alveolar ventilation 120-140 60-70 mL/kg/min
RR 30-40 10-15 breath/min
I:E 1 1.5
FRC 30 30 mL/kg
Specific compliance 0.05 0.05 /cmH2O
Oxygen consumption 6-7 3-3.5 mL/kg/min

NB: Foetal oxygen consumption at term = 5 mL/kg/min

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Physiological anaemia of pregnancy

[KB2:p6]

During pregnancy,

Blood volume increase by 40 to 45% by term

Plasma volume increase by 50% by term

--> Hemodilution

--> Physiological anaemia of pregnancy

NB:



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