Fetal surveillance - FHT monitoring Flashcards Preview

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Flashcards in Fetal surveillance - FHT monitoring Deck (19):
1

Guidelines for intrapartal FHR monitoring

  • 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
  • High risk patients
    • Continuous EFM
      • Documented systematic assessment every hour

2

Internal versus external fetal monitoring

  • Internal
  • External
    • Invasiveness
    • Principle

  • 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

Baseline FHR

  • Definition
  • Normal value

 

  • 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

Minimum time to measure FHR

  • duration must be at least 2 minutes
  • if minimum baseline duration is < 2 minutes then the baseline is indeterminate

5

Causes of fetal tachycardia

  • 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

Management of tachycardia

  • Reposition woman
  • Rule out fever, dehydration, drug effect, prematurity
  • Correct maternal hypovolemia, if present
  • Check maternal pulse and BP

7

Causes of bradycardia

  • 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

Management of bradycardia

  • 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

Baseline abnormality suggestive of neurological abnormality

Wandering – unsteady FHR baseline between 110 to 160bpm

10

Baseline variability

  • Definition
  • Normal value
  • Significance of variability
  • Exclusion

  • 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

Types of variability and their description

  • Absent
    • no detectable variation
  • Minimal
    • <5 bpm
  • Moderate
    • 6 – 25 bpm
  • Marked
    • > 25 bpm

12

T/F. Moderate variability is always predictive of good outcome.

False (as in abruption)

13

Acceleration

  • Definition
  • Values

  • 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

14

Significance of absence of acceleration

The absence of accelerations for more than 80 minutes correlates with increased neonatal morbidity

15

Relationship of FHR acceleration and NST

Reactive NST = 2 or more accelerations over 20 min = fetal well-being

16

Prolonged acceleration definition

Lasts > 2 minutes but < 10 minutes in duration

17

What if the acceleration lasts > 10 minutes?

Change in baseline

18

Action if the NST is nonreactive

  • the baby may be asleep
    • if this is suspected, ask the patient to eat or drink to make the baby active
    • if not reactive within 1–2 hours, then additional testing may need to be performed

19

How to report IPM reading

  • Baseline FHT in increments of 5 (e.g. 145-150)
  • Variability (absent, minimal, moderate, marked)
  • Accelerations (+/-)
  • Decelerations (early, late, variable, to as low as __)
  • Contractions every __ min, lasting __, mild, moderate, strong)