Uteroplacental & Fetal Physiology Pt. 4 (Exam 2) Flashcards
(38 cards)
What are the three main factors affecting fetal oxygenation?
- Maternal BP
- Maternal oxygenation
- Umbilical cord patency
How does the fetus protect itself in the instance of hypoxia?
- ↓ endothelial NO ⇒ vasoconstriction ⇒ blood flow redistribution
- ↑ Adenosine accumulation ⇒ cerebral vasodilation
Why does a fetus have bradycardia in response to hypoxia?
- chemoreceptor stimulation ⇒ peripheral vasoconstriction
- Vagal response ⇒ bradycardia (predominant parasympathetic system)
Where is more blood shunted in the event of fetal hypoxia?
Ductus venosus & ↑O₂ delivery to heart & brain
What are the results of chronic fetal hypoxia? (weeks of months)
- Fetal growth restriction
- Impaired organ function (brain, kidney)
- Cardiomyocyte apoptosis
- Fetal demise
What are the two ways that fetal heart rate can be monitored?
- External: surface doppler ultrasound
- Internal: fetal scalp electrode
External monitoring of uterine contractions is known as ________.
This method of monitoring can determine what?
TOCO
Contraction Frequency only
How does internal uterine pressure catheter monitoring (IUPC) differ from external (TOCO) monitoring?
IUPC can monitor contraction frequency and strength (i.e. intrauterine pressure).
The fetus depends on the _______ _______ during contractions to maintain oxygenation.
What metaphor for this was using during labor?
Cardiopulmonary reserve
- Poor reserve oxygen leads to decompensation
Swimmer holding their breath underwater for 30-60 seconds every 2-3 minutes.
What problems with the placenta present a problem with fetal oxygenation that are not likely reversible?
- Abruption (tear away from uterine wall)
- Infarction
- Too small of a placenta
- ↑ placental resistance
What are the two problems with the uterus that result in fetal oxygenation impairment?
- Tachysystole (excessive contraction frequency)
- Tetanic Contraction (sustained and forceful)
What are the two problems on the maternal side that result in fetal oxygenation impairment?
- Hypotension
- Hypoxia
Uterine contractions are quantified over a ______ period and averaged over ____ minutes.
10 minute period : averaged over 30 minutes
Uterine contractions are measured from ___________ of one contraction to _________ of the next.
Uterine contractions are measured from the beginning of one contraction to the beginning of the next
.
What is considered a “normal” amount of contractions?
≤ 5 contractions in 10 minutes
Tachysystole is defined by > ______ contractions in a 10 minute period.
5
How is tachysystole treated?
- Stop Pitocin gtt (if running)
- Nitroglycerin (sublingual or IV) to relax uterus
- Terbutaline (β2 agonist)
How is a baseline FHR calculated?
Mean FHR rounded to increments of 5bpm during a 10 minute period.
What is the normal FHR range?
110 - 160 bpm
What defines FHR tachycardia?
Bradycardia?
- Tachycardia: > 160 bpm
- Bradycardia: < 110 bpm
What are some common causes of fetal tachycardia originating from issues on the fetal side?
- Chorioamnionitis
- Sepsis
- Acute fetal hypoxia
- Fetal heart failure
- Anemia
What are some common causes of fetal tachycardia originating from issues on the maternal side?
- Maternal hyperthyroidism
- Maternal fever
- Epi / ephedrine use
- β2 agonists (Ritodrine, terbutaline)
What are the common causes of fetal bradycardia?
- Hypoxemia (umbilical compression or fetal head compression)
- Hypothermia
- Maternal HoTN
- Maternal hypoglycemia
- Congenital heart block
What is the fetus’s initial response to hypoxemia?
fetal Bradycardia
