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

 

 

=====

[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

=====

 

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:

• RBC volume increase by 250mL (18%) without iron supplementation
• RBC volume increase by 450mL (30%) with iron supplementation