Fetal Physiology Flashcards
What proportion of fetal calories are used for growth? What makes up the calories?
30-40%
Glucose - 50%
AA - 25%
Lactate - 20%
Acetate - 5%
What is glucose stored in the fetas?
In the as month in utero as glycogen
How does water content change throughout gestation and birth?
TBW decreases due to drop in ECF (80% at 5 months, 75% at term)
ICF increases relatively
How much weight to babies loose? Why?
10% if term
15% if preterm
Due to water lose
What are the three important shunts?
Ductus venosus
Foramen ovale
Ductus arteriosus
What is the distribution of CO in the fetus?
Placenta 40%
Brain 30%
Hindquarters 18%
Lungs 4%
What is a fetal scalp lactate?
Sample of scalp taken during delivery to assess O2 status
What happens to the circulation at birth?
Placenta removed
Shunts closes
PulmonaryVR falls
Parallel > Series
What are the normal saturations of the fetus after delivery?
Around 50 > rises to 100% after 5 minutes
Why do babies get anaemic early?
Nadir in Hb after dropping from higher Hb level in utero
Also iatrogenic in preterms
When do alveoli develop the capacity of O2 exchange?
22-24 weeks
Where does fetal lung liquid come from?
Produced in the lung
What controls fetal lung fluid levels?
Adrenaline produces it
- Therefore can be wet lungs (transient tachypnoea on the newborns) with C-sections
How is fetal lung fluid removed?
Negative thoracic pressure absorbs it
Squeezed out during delivery
What is a complications of oligohydramnios?
Poor lung development due to lack of lung fluid
