Lecture 13: Fetal Heart Monitoring Flashcards

1
Q

What is the pressure sensitive tocodynanmometer transducer useful for measuring?

A

Measures frequency of contractons; but NOT the strength

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2
Q

Using a fetal scalp electrode for internal monitoring should be avoided in which patients?

A

HIV patients

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3
Q

Internal electronic fetal monitoring requires what?

A

The membranes to be ruptured

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4
Q

What is the pH of fetal scalp blood that is considered abnormal (fetal acidosis)?

A

pH <7.20

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5
Q

What is considered normal vs. tachysystole for uterine contractions when monitoring?

A
  • Normal = 5 contractions or less in 10 minutes, averaged over 30 mins
  • Tachysystole = >5 contractions in 10 minutes, averaged over 30 mins
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6
Q

How do you measure Montevideo units; what do they indicate; what is normal?

A
  • Measure the strength of contractions in a 10 minute period (summed together)
  • >200 MVU’s is adequate
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7
Q

What is your evaluation of the uterus based on this strip?

A

Tachysystole

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8
Q

When monitoring FHR, at what point on the strip do you assess?

A

Between contractions

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9
Q

What is a normal FHR, tachycardia, and bradycardia?

A
  • Normal = 110-160 bpm
  • Tachy = >160 bpm
  • Brady = <110 bpm
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10
Q

Which FHR is an early sign and which is a late sign of fetal hypoxia?

A
  • Tachycardia is an early sign of hypoxia
  • Bradycardia is a late sign of hypoxia
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11
Q

What is the most common cause of fetal tachycardia?

A

Fetal infections –> Chorioamnionitis

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12
Q

What is the normal amount of variability in amplitude with FHR?

A

Moderate (normal) = range of 6-25 bpm

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13
Q

What is decreased baseline variability of the FHR an indicator of and when is it an ominous sign?

A
  • Sign of fetal stress, is assoc. w/ hypoxia and acidemia
  • Is ominous sign with persistent late decelerations
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14
Q

What is considered an acceleration of FHR at ≥ 32 weeks and at <32 weeks gestation?

A
  • ≥ 32 weeks: HR ≥ 15 bpm above baseline for 15 sec or more (but <2 mins)
  • <32 weeks: HR ≥ 10 bpm above baselines for 10 sec or more (but <2 mins)
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15
Q

What is considered a prolonged acceleration of FHR and how long is considered a change in baseline?

A
  • Prolonged acceleration = ≥ 2 mins
  • Change in baseline = ≥ 10 mins
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16
Q

What is the cause of early deceleration of FHR and how are they seen on monitor?

A
  • Occur 2’ to head compression; fetal autonomic response to ↑ ICP —> ↓ in HR
  • NOT assoc. with fetal distress
  • The lowest point of deceleration occur at the same time as the peak of contraction = “mirror image
17
Q

When do variable decelerations of FHR occur?

A

Secondary to umbilical cord compression

18
Q

How do variable decelerations of FHR appear on monitor; what is the criteria?

A
  • Abrupt ↓ in FHR ≥ 15 bpm lasting ≥ 15 sec and <2 min (looks like big ‘V’)
  • Can occur before, during, or after the contraction
19
Q

What is the cause of late decelerations on fetal heart monitoring; why are they a bad sign?

A
  • Caused by uterine placental insufficiency (UPI)
  • Most ominous type –> repetitive decelerations usually indicate fetal metabolic acidosis and low arterial pH
20
Q

How do late decelerations appear on fetal heart monitor?

A

Lowest point of deceleration occurs after peak of the contraction

21
Q

When are prolonged decelerations commonly seen on monitor?

A

During maternal pushing

22
Q

When is a sinusoidal pattern seen on fetal heart monitoring?

A

Seen w/ fetal anemia

23
Q

What kind of variability, accelerations, and decelerations may be seen in category I interpretation of FHR pattern?

A
  • Moderate variability
  • NO late or variable decelerations
  • Accelerations and early decelerations may or may not be present
24
Q

What are the goals and management for category II, recurrent variable decelerations (>50% of contractions)?

A
  • GOAL: alleviate cord compression
  • Repositioning amnioinfusion (1st stage of labor)
  • Modify pushing efforts: have Mom push w/ every other CTX
25
Q

What are the goals and management of category II, tachysystole, if seen on fetal heart monitoring?

A
  • GOAL: to reduce uterine activity
  • Lateral positioning + IV bolus + ↓ oxytocin rate or discontinue
  • If no response, give uterine tocolytic (Terbutaline SQ or IV)
26
Q

What seen on fetal heart rate tracing would be considered category III?

A
  • Recurrent late decelerations or variable decels or bradycardia
  • Sinusoidal pattern
27
Q

When would you do fetal scalp stimulation and what is a normal response?

A
  • Useful to differentiate fetal sleep from acidosis, when fetal tracing shows reduced variability but no decelerations
  • When scalp stimulated: acceleration of 15 bpm lasting 15 sec occurs then the fetal pH value almost always is 7.2 or greater
28
Q

What are 2 potential causes of late decelerations?

A
  • Excessive uterine activity
  • Maternal supine HYPOtension