Reduced baseline variability and acclerations

Question 1

Deep Fetal Sleep

Answer 1

sleep wake cycle of 20 to 40 minutes

sleep phase fetus may withdrawn some PSN input to the SA node may see an minor rise in the baseline rate

variability many be reduced to diminished feedback required from the CRC which is physiologically reasonable

Question 2

Drugs and Medications

Answer 2

drugs that affect the fetal CNS
1. Narcotics such as morphine and fentanyl
2. Calcium Channel blockers particularly IV magnesium sulphate may reduce baseline variability
3 local anaesthetics such as epidurals many reduce baseline variability
4. Beta blockers suprress sympathetic stimulation and might reduce the baseline rate as well as the amplitude of accelerations
5. some antiepileptic or antipsychotic meds are known to impact fetal baseline variability as have glue-coritico steroids

Question 3

Extreme Prematurity

Answer 3

very premature fetus has an immature PNS
it is inherently sympathetically dominant
reasonable cause of both reduced BV and the amplitude of acclerations

fetuses are less likely to be monitored by CTG being typically less than 25 weeks gestation

Question 4

Hypoxia

Answer 4

cause of reduced baseline variability
occurs through the utero placental insufficiency and changes in biophysical activity in the chronically hypoxic fetus

more acutely hypoxic fetus is the alteration to the balance of the SNS & PNS CNS innervation

Question 5

CTG abnormalities arris as a result of hypoxia

Answer 5

1. abnormalities of the fetal heart rate pattern which will support the diagnosis
2. rising baseline or baseline tachycardia
3. late decelerations
4. absent of any physiologically reassuring features

** the total clinical picture or degree of risk will also add important clinical information