Chapter 14: Intrapartum Fetal Surveillance Flashcards
What are the purposes of intrapartum fetal assessments?
- Evaluate how the fetus tolerates labor
2. Identifies hypoxic insult to the fetus during labor
Adequate fetal oxygenation needs five related factors:
- Normal maternal blood flow and volume to the placenta
- Normal oxygen saturation in maternal blood
- Adequate exchange of oxygen and carbon dioxide in the placenta
- An open circulatory path between the placenta and the fetus through vessels in the umbilical cord.
- Normal fetal circulatory and oxygen-carrying functions.
How can uterine activity affect uteroplacental exchange?
- During labor, contractions gradually compress the spiral arteries, temporarily stopping maternal blood flow to the fetus.
- Fetus depends on the oxygen supply already present in body cells, erythrocytes and intervillous spaces. (Oxygen supply is enough for about 1-2 minutes)
What can affect uteroplacental exchange and fetal oxygenation?
- Uterine Activity
- Placental Disruptions
- Fetal Alterations
- Maternal Cardiopulmonary Alterations
- Interruptions in Umbilical Flow
How can placental disruptions affect uteroplacental exchange?
- Abruptio placenta (reduces the placental surface area available for exchange)
- Placenta previa (blood loss = decreased BF to fetus)
Abruptio Placenta
Premature separation of a normally implanted placenta
Placenta Previa
Abnormal implantation of the placenta in the lower uterus at or very near the cervical os.
Uterine Activity Assessment: External
Placements of monitor on top of the fundus to detect contractions.
What maternal cardiopulmonary alterations can affect fetal oxygenation?
- Aortocaval compression
- Maternal HTN
- Maternal acid-base alterations
- Hemorrhage
How does aortocaval compression affect fetal oxygenation?
- It occurs when a pregnant woman lies in supine position and the weight of the uterus compresses the aorta and the inferior vena cava.
- Thus, it reduces blood return to her heart, lowers her CO, and can reduce placental perfusion.
What can interrupt umbilical blood flow and oxygenation to the fetus?
- Compression by a unchallenged cord (one that is wrapped around the fetal neck) or by a not in the cord.
- Oligohydramnios (d/t inadequate amniotic fluid to cushion the cord)
- Inadequate Wharton’s Jelly
What are fetal alterations that can affect fetal oxygenation?
- Low circulation fetal blood volume
- Fetal hypotension
- Fetal anemia
Fetal Assessment
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Position and Presentation of the ..
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Leopold’s Maneuver
- Provide a systematic method for palpating the fetus through the abdominal wall during the later part of pregnancy.
- These maneuvers provide valuable information about the location and presentation of the fetus
What is a normal fetal heart rate?
110-160 bmp
Intermittent Electronic Fetal Monitoring
Done with a short strip taken at regular intervals during labor or during early labor
Continuous Electronic Fetal Monitoring
Starts shortly after the woman is admitted.
When should you use intermittent electronic fetal monitoring?
For high-risk patients such as DM
When should you use continuous electronic fetal monitoring?
When coming in for labor or when on any medications.
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Reactivity
If baby is nonreactive, baby is not getting enough perfusion.
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Fetal Scalp Electrode
Detects electric signals from the fetal heart.
Can become easily displaced.
What are causes of fetal tachycardia?
- Maternal fever
- Maternal dehydration
- Maternal or fetal hypoxia
- Fetal acidosis
- Maternal or fetal Hypovolemia
- Fetal cardiac dysrhythmias
- Maternal severe anemia
- Maternal Hyperthyroidism
- Drugs administered to mother
What are causes of fetal bradycardia?
- Tachysystole
- Maternal hypotension
- Fetal head compression
- Fetal hypoxia
- Fetal acidosis
- Fetal heart block
- Umbilical cord compression -> oligohydramnios
- abruptio placenta
- Late second-stage labor with maternal pushing
*anything that removes BF will drop HR
Tachysystole
When the contractions are so frequent and never return to baseline → no oxygen is getting to the fetus during the “relaxation periods” because the contractions have no relaxation periods.
Early Decelerations: Characteristics
- Requires no intervention.
- Has a gradual decrease from baseline.
- Mirrors contractions
- Consistent appearance
Late Decelerations: Characteristics
- Nonreassuring
- Deceleration begin AFTER the peak of contraction.
- FHR returns to baseline AFTER the contraction ends
- Consistent appearance
- Gradual fall and rise
Variable Decelerations: Characteristics
- Do not have uniform appearance
- Shape, duration and degree of fall below baseline rate vary
- Fall and rise abruptly with the onset and relief of cord compression
- Nonperiodic (occurring at times unrelated to contractions)
- Decrease in FHR is at least 15 bpm and lasts at least 15 seconds but less than 2 minutes.
What are interventions for nonreassuring decelerations such as late and variable decelerations?
1st: turn mom on left side for optimal perfusion (or turn to other side)
2. Stop medications
3. Increase fluids, hydrate, IV
4. Last resort, oxygen, rebreather, 8-10L
VEAL CHOP
Variable -> Cord
Early -> Head
Acceleration -> OK
Late -> Placenta
Baseline Fetal Heart Rate Variability
Denotes the fluctuations in the baseline FHR within a 10-minute window that cause the printed line to have an irregular rather than smooth appearance.
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External Fetal Monitoring
- Slightly less accurate than internal but are noninvasive.
- Includes external sensors, ultrasound transducer and tocotransducers.
Internal Fetal Monitoring
- Are invading and the risk of infection is slightly increased.
- Includes Intrauterine Pressure Catheters and Fetal Scalp Electrodes.
- More accurate than external.
Tocotransducer
Detects changes in abdominal contour to measure uterine activity.
Doppler ultrasound transducer
Detect movement other than fetal heart motion such as fetal or maternal activity or blood flow through the umbilical cord and the woman’s aorta.
What causes late decelerations?
- Caused by deficient exchange of oxygen and wast products in the placenta (UTEROPLACENTAL INSUFFICIENCY)
- May occur with conditions such as maternal HTN and diabetes which impair placental exchange.
What causes early decelerations?
FETAL HEAD COMPRESSIONS briefly increase intracranial pressure, causing the vagus nerve to slow the heart rate.
What do late decelerations suggest?
Suggests that fetus has reduced reserve to tolerate recurrent oxygen reductions in oxygen supply that occurs with contractions.
What causes variable decelerations?
Conditions that reduce the flow through the UMBILICAL CORD.
Fetal Tachycardia
Baseline fetal heart rate greater than 160 bpm for at least 10 minutes
Fetal Bradycardia
Baseline fetal heart rate less than 110 bpm for at least 10 minutes
Intrauterine pressure catheter (IUPC)
Can be used to measure uterine activity including contraction intensity and resting tone.
FHR Baseline
Is the average heart rate, rounded to 5 bpm, measure over 2 minutes of clear tracing within a 10-minute window.
(During this 2 or more minutes, the uterus must be at rest and episodes of significant increases or decreases in rate must not occur)
Accelerations
An abrupt, temporary increase in the FHR that peaks at least 15 bpm above the baseline and lasts at least 15 seconds. (15x15)
Usually reassuring sign.
Internal FSE parameters
…table 14-6
Fetal Tachycardia: Nursing Interventions
Table 14-1
Fetal Bradycardia: Nursing Interventions
Table 14-1
What are nonpathalogic causes of FHR variability?
- alcohol, illicit drugs
- narcotics or other sedatives
(NOT SURE IF THESE ARE CONSIDERED PATHOLOGIC OR NONPATHOLOGIC)
What are pathologic causes of FHR variability?
- fetal sleep
- fetal sepsis
- fetal tachycardia
- extreme prematurity
- fetal anomalies that affect CNS regulation
- hypoxia severe enough to affect CNS
- abnormalities of CNS, heart or both
- maternal hypoxemia or acidemia
(NOT SURE IF THESE ARE CONSIDERED PATHOLOGIC OR NONPATHOLOGIC)
FHR Variability: Nursing Interventions
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Reassuring (Reactive)
- At least two fetal heart accelerations with or without fetal movement, occur within a 20-minute period, peak at least 15 bpm above the baseline and lasts 15 seconds (15x15).
- An additional 40 minutes of testing time may be needed to allow for fetal sleep-wake cycles.
Indeterminate/Nonreassuring
Tracing does not demonstrate required characteristics of a reactive tracing within a 40 minute period.
How is Leopold’s Maneuver done?
Procedure 13-1 in book
Look up on YouTube
What are the two types of intrauterine pressure catheters?
- Solid catheter with a pressure transducer tip (may have additional lumen for amnioinfusion)
- A hollow, fluid-filled catheter that connects to a pressure transducer.
Solid Catheter
- Not affected by height because transducer is in the catheter.
- Intrauterine pressures are higher than those from fluid-filled catheter.
- Simpler to use.
Fluid-filled Catheter
- Should be at level of the transducer on the outside for best accuracy.
- If tip is lower than the transducer, the recorded pressure is lower than the actual intrauterine pressure and vice versa.
What are the advantages of electronic fetal monitoring?
Has not been shown to be superior to auscultation with palpation, but more staff may be needed to achieve safe, intermittent auscultation with palpation.
Parasympathetic Nervous System in the fetus
Matures later than the sympathetic beginning at about 28-32 weeks of gestation.
What is an advantage of a fetoscope over a Doppler ultrasound device?
The fetoscope assesses the actual fetal heart sounds and therefore can be used to reliably identify fetal cardiac dysrhythmias.
Doppler devices sense cardiac motion and convert the motion into sound that represents cardiac activity.
Nursing Responsibilities related to intrapartum fetal monitoring include:
- Promoting fetal oxygenation
- Identifying and reporting nonreassuring findings
- Supporting parents
- Communicating with the physician or nurse-midwife
- Documenting all care
How can anesthesia affect perfusion to fetus?
May cause vasodilation -> hypotension (the amount of blood to fill her vessels is unchanged) -> reduction of placental blood flow
Hypertonic contractions
Reduces the time available for exchange of oxygen and waste products in the placenta.
Which is the most appropriate method of intrapartum fetal monitoring when a woman has a history of hypertension during pregnancy?
Continuous electronic fetal monitoring
When the mothers membranes rupture during active labor, the fetal heart rate should be observed for the occurrence of which periodic pattern?
Variable decelerations
In which situation would it be appropriate to obtain a fetal scalp blood sample to establish fetal well-being?
The tracing is nonreassuring, and additional assessment is needed regarding the acid-base status of the fetus.
Fetal scalp blood sampling is contraindicated with vaginal bleeding, maternal fever, and a preterm fetus.