Fetal surveillance - FHT monitoring Flashcards
1
Q
Guidelines for intrapartal FHR monitoring
A
- Low risk patients
- Auscultation
- 1st stage - q15 minutes X 1 minute soon after a contraction
- 2nd stage - q5 minutes or every after contraction
- Maternal pulse should be differentiated from fetal pulse
- Frequency and duration of maternal contractions should be noted
- Auscultation
- High risk patients
- Continuous EFM
- Documented systematic assessment every hour
- Continuous EFM
2
Q
Internal versus external fetal monitoring
- Internal
- External
- Invasiveness
- Principle
A
- Internal
- Non-invasive
- Utilizes ultrasonic wave (UTZ Doppler principle)
- External
- Invasive (rupture of membranes + uterine invasion)
- Utilizes a bipolar spiral electrode
- 1st pole: wire electrode that penetrates scalp
- 2nd pole: metal wing on the electrode
- Attached to a reference electrode on the maternal thigh to eliminate electrical interference
- Vaginal body fluids create a saline electrical bridge that completes the circuit and permits measurement of the voltage differences between the two poles
3
Q
Baseline FHR
- Definition
- Normal value
A
- Definition
- Heart rate during a 10 minute segment rounded to the nearest 5 beat per minute increment excluding segments that differe by > 25 bpm
- Normal value
- 110 - 160 bpm
4
Q
Minimum time to measure FHR
A
- duration must be at least 2 minutes
- if minimum baseline duration is < 2 minutes then the baseline is indeterminate
5
Q
Causes of fetal tachycardia
A
- fetal hypoxemia
- drugs (atropine, vistaril, phenothiazine, beta-sympathomimetics
- tachyarrhythmias
- maternal infection
- chorioamnioniti
- fetal sepsis
- fetal heart failure
- severe fetal anemia
- fetal hydrops
- maternal hyperthyroidism
6
Q
Management of tachycardia
A
- Reposition woman
- Rule out fever, dehydration, drug effect, prematurity
- Correct maternal hypovolemia, if present
- Check maternal pulse and BP
7
Q
Causes of bradycardia
A
- hypoxemia
- drugs
- maternal hypotension
- hypothermia
- maternal hypoglycemia
- complete heart block (maternal SLE, CMV infections)
- congenital heart block
- umbilical cord compression
- amniotic fluid embolism
- normal variation
8
Q
Management of bradycardia
A
- Reposition woman
- Perform vaginal exam to assess prolapsed cord
- Administer oxygen at 8-10 L/min
- Correct maternal hypovolemia, if present
- Check maternal pulse and BP
9
Q
Baseline abnormality suggestive of neurological abnormality
A
Wandering – unsteady FHR baseline between 110 to 160bpm
10
Q
Baseline variability
- Definition
- Normal value
- Significance of variability
- Exclusion
A
- Definition
- oscillation in baseline FHR > 2 cycles per minute
- beat-to-beat irregularity and waviness of the FHR
- Normal value
- Moderate (6-25 bpm)
- Significance of variability
- An intact and mature brain stem and heart
- Signifies interaction between the parasympathetic and sympathetic nervous system which determine the cardiac output and heart rate in response to the venous return and metabolic demands of the fetus
- Exclusions
- Deceleration
- Acceleration
- Sinusoidal pattern
11
Q
Types of variability and their description
A
- Absent
- no detectable variation
- Minimal
- <5 bpm
- Moderate
- 6 – 25 bpm
- Marked
- > 25 bpm
12
Q
T/F. Moderate variability is always predictive of good outcome.
A
False (as in abruption)
13
Q
Acceleration
- Definition
- Values
A
- Definition
- Visually apparent abrupt increase in FHR above baseline, with the time from the onset of the acceleration to its acme of < 30 seconds
- Values
- <32 weeks
- >10 bpm above baseline for >10 seconds but < 2 minutes
- > 32 weeks
- >15 bpm above baseline for > 15 seconds but < 2 minutes
- <32 weeks
14
Q
Significance of absence of acceleration
A
The absence of accelerations for more than 80 minutes correlates with increased neonatal morbidity
15
Q
Relationship of FHR acceleration and NST
A
Reactive NST = 2 or more accelerations over 20 min = fetal well-being
