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Fetal Oxygenation Placental Physiology Maternal blood flows through the uterine arteries into the intervillous spaces then return through uterine veins.

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Presentation on theme: "Fetal Oxygenation Placental Physiology Maternal blood flows through the uterine arteries into the intervillous spaces then return through uterine veins."— Presentation transcript:

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2 Fetal Oxygenation

3 Placental Physiology Maternal blood flows through the uterine arteries into the intervillous spaces then return through uterine veins to maternal circulation Fetal blood flows through the umbilical arteries into the villous capillaries and returns through the umbilical vein to fetal circulation. Exchange of blood gases depends on an unobstructed blood flow through the placenta.

4 Uteroplacental exchange As the myometrium contracts, the flow of oxygenated blood through the uterine artery may be decreased. Therefore, the fetus may have less oxygen available.

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6 Regulation of Fetal Heart Rate Autonomic nervous system Baroreceptors Chemoreceptors Adrenal Gland Central Nervous System

7 Electronic Fetal Monitoring Standard of Care “Nurses who care for women during the childbirth process are legally responsible for correctly interpreting FHR patterns, initiating appropriate nursing interventions based on the pattern seen, and documenting the outcome of those interventions.”

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9 Indications for Electronic Fetal Monitoring Previous history of stillbirth Complications of pregnancy Induction of Labor Preterm labor Nonreassuring fetal status; fetal movement Meconium staining of amniotic fluid

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11 Advantages of EFM Constant sound of FHR is reassuring and comforting to the family Supplies more data about the fetus and gradual trends in FHR are more apparent Coach uses strip pattern tracing to assist with support

12 Disadvantages of EFM Reduces patient’s mobility Requires repositioning of equipment with fetal or maternal movement Can impart a technical air to the birth process

13 Methods of Fetal Monitoring Intermittent ausculation by doppler Continuous external monitoring Continuous internal monitoring

14 Auscultation by Doppler Intermittent auscultation can be done with a Fetascope or Doppler for FHT’s

15 External Monitoring Information from both the toco and the ultrasound device is transmitted to the electronic fetal monitor. The FHR is displayed in a digital display (as a blinking light), on the special monitor paper, and audibly (by adjusting a button on the monitor). The uterine contractions are displayed on the special monitor paper as well. The tocodynamometer (“toco”) is placed over the uterine fundus. The toco provides information that can be used to monitor uterine contractions. The ultrasound device is placed over the area of the fetal back. This device transmits information about the FHR.

16 Internal Monitoring Spiral Electrode is placed on the fetal occiput which allows for more accurate continuous data then external monitoring. Also is not affected by mom or fetal movement as with external monitoring. Criteria for Internal Monitoring:  Amniotic membranes must be ruptured  Cervix dilated 2 cm.  Presenting part down against the cervix

17 Internal Monitoring The spiral electrode is attached to the fetal scalp Wires that extend from attached spiral electrode are attached to a leg plate and then attached to electronic fetal monitor.

18 Nursing Responsibilities Electronic Fetal Monitoring Placement of equipment Teaching the woman about use Notation of events on the strip Evaluation of data Intervention as indicated by data

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20 Baseline Fetal Heartrate Normal Pattern Baseline FHR = 120 – 160 bpm

21 Patterns Tachycardia – baseline above 160 BPM –RT= maternal fever, fetal hypoxia, intrauterine infection, drugs Bradycardia – baseline below 110 BPM –RT = profound hypoxia, anesthesia, beta-adrenergic blocking drugs

22 Variability Normal/ increased variability or irregularity of a cardiac rhythm. Absence or decreased variability, or a smooth flat baseline, is a sign of fetal compromise.

23 Causes of Decreased Variability Hypoxia and acidosisMedicationsSleep cyclePreterm status

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25 Periodic changes in the FHR Accelerations – increase in the fetal heart rate with a return to baseline. Indication of fetal well-being is an acceleration of 15 bpm for 15 seconds.

26 Reassuring Acceleration Pattern Baseline fetal heart rate is with preserved beat-to-beat variability. Accelerations last for 15 or more seconds above baseline, and peak to 15 or more bpm.

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28 Periodic changes in the FHR Decelerations Early – related to head compressions. Interventions not necessary Variable – related to cord compression. Interventions vary, but focus on position changes. Late – related to uteroplacental insufficiency. Most ominous and need immediate attention.

29 Early Deceleration The onset and return of the deceleration coincide with the start and end of the contraction. Fetal Heart Rate Contractions

30 Early Decelerations Related to Head Compression Intervention –No intervention necessary. Just continue to watch for any changes.

31 Variable Deceleration Variable decelerations are variable in duration, intensity, and timing

32 Variable Decelerations Related to cord compression Intervention –Reposition –Amnioinfusion

33 Late Deceleration The fetal heart tones return to the baseline AFTER end of contraction

34 Late Decelerations Related to decreased uteroplacental perfusion

35 Nursing Care for FHR Decelerations Stop the Pitocin Reposition - Turn woman to a side-lying position, or knee- chest position. Avoid supine position Increase rate of the mainline IV Administer oxygen by mask at 10 L/min. Give Terbutaline sub- q.

36 Nursing Care Notify the primary care provider If condition does not improve, then prepare for immediate delivery

37 Fetal Scalp Stimulation Gently stroke or massage fetal scalp for 15 sec. during a vaginal examination Assess fetal tracing for signs of accelerations of 15 bpm for 15 sec. This is a sign of fetal well-being

38 Fetal Scalp Blood Sampling Requires rupture of membranes Acidosis is present if the pH is less than 7.20

39 Cord Blood Analysis Criteria –Significant abnormal FHR –Meconium stained amniotic fluid –Infant is depressed at birth Small amount of blood obtained from umbilical cord and tested for acidosis –Normal fetal blood pH should be >7.25 –Lower level indicate acidosis and hypoxia

40 Montevideo Units Montevideo units is a measure of uterine contraction intensity during labor. Units are calculated via internal pressure monitor, measuring uterine contraction peak pressure and subtracting the baseline resting tone. This is done over a 10 minute interval. Generally, above 200 MVUs is considered necessary for adequate labor to bring about dilation and effacement during the active phase.

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