Fetal Health Surveillance

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Fetal Health Surveillance

• Electronic Fetal Monitoring
• Susan Schank
• Regional Education Services 2005

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Aim of Intrapartum Fetal Surveillance

• Why do we do fetal monitoring?
• The aim of intrapartum fetal surveillance is to
  improve fetal outcomes by identifying fetuses
  with hypoxic acidemia at a point when the process
  is still completely reversible by intrauterine
  resuscitation or expedited delivery.
• SOGC (2002)

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Indications for EFM

• What are the indications for EFM?
• In the presence of abnormal FHR characteristics
  detected by intermittent auscultation and
  unresponsive to resuscitative measures, increased
  surveillance by continuous EFM or fetal scalp
  sampling or delivery should be instituted.
• SOGC (2002)

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Antepartum (not in labour)

• Fetal heart is recorded by external ultrasound
  transducer
• Contractions are recorded by Tocodynanometer
  (toco)
• Duration often short (minimum 20 minutes to 1
  hour)

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Advantages of External Monitoring

• Can be done anytime
• Convenient
• Noninvasive
• Easy to apply
• Provides a continuous tracing
• Frequency of contractions is easily obtained
• Minimal fetal or maternal complications

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Disadvantages of External Monitoring

• Difficult to obtain a tracing in obese or active
  patient
• Picks up artifacts e.g. maternal pulse
• Limits patient movement
• Variability cannot be recorded accurately
• No information on the quality or intensity of
  contractions

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Uteroplacental Physiology

• Passive diffusion of nutrients, oxygen etc.
  across placental barrier
• Compromised maternal blood flow to placenta
  placental insufficiency
• Chronic insufficiency IUGR
• Rapidly occurring insufficiency fetal distress

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Purpose of a NST

• Assessment of fetal well-being during the
  antepartum or intrapartum period
• Assists in identifying the fetus that is at risk
  for alterations in oxygenation
• NST is a screening tool - not diagnostic
• An abnormal NST indicates further testing is
  required

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Who should have a NST?

• Preeclampsia
• Gestational Hypertension
• Diabetes
• Cardiac disease
• Antepartum bleeding
• IUGR
• Meconium staining

• Prematurity
• Postmaturity
• Abnormal heart rate
• Uterine dystocia
• Inductions/augmentation
• Decreased fetal movement
• Maternal trauma

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Fetal Monitor Paper

• 1 cm 2 squares (1 cm/min) now a provincial
  standard Alberta Perinatal Health Program
• Paper speed and date/time may be recorded on the
  tracing make sure these are correct
• Records both fetal heart rate and uterine
  activity

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Uterine activity

• Frequency start of one contraction to the start
  of the next (normal is 2-3 minutes)
• Duration start of one contraction to the end of
  the same (normal is 45-60 seconds)
• INTENSITY cannot be determined by a toco the
  womans fundus must be palpated to determine the
  intensity of the contractions
• Baseline Tone refers to the relaxation of the
  uterus between contractions.

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Baseline Fetal Heart Rate

• The average FHR between contractions
• Excluding periods of accelerations, decelerations
  and marked variability
• Over a ten minute period
• Normal range 110-160 bpm (32 weeks and gt)
• Interval between periodic changes, contractions,
  and fetal movement (120 160 bpm for 28-32 weeks)

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Tachycardia/Bradycardia

• Tachycardia FHR baseline gt 160 bpm for 10
  minutes or longer
• Causes are fetal hypoxia, drugs (eg. atropine),
  prematurity, maternal fever, fetal infection
• Bradycardia FHR baseline lt 110 bpm that
  persists for 10 minutes or longer
• Fetal hypoxia, drugs (eg. beta blockers),
  maternal fetal cardiac arrhythmias, maternal
  hypothermia

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Changing Baseline

• A changing baseline progressing toward
  tachycardia is significant
• The fetus is having to work harder to get the
  oxygen he needs
• Tachycardia may be an early sign of fetal hypoxia
  as the fetus attempts to compensate!
• Bradycardia may be a late indication of hypoxia
  when the fetus can no longer compensate!

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Baseline FHR Variability

• Variability is believed to be the most
  significant indicator of fetal well-being
• Normal, irregular beat to beat changes
  fluctuations in FHR
• Indicates mature, fetal neurologic system
• Measure of fetal reserve
• Push-pull of parasympathetic/sympathetic nervous
  system

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Variability

• Variability classified as
• Absent amplitude of variability not detectable
• Minimal amplitude detectable but lt 6 bpm
• Moderate amplitude ranges from 6-25 bpm
• Increased amplitude is gt25 bpm
• SOGC (2002)
• Decreased variability may be caused by hypoxia,
  prematurity, fetal sleep, drugs, preexisting
  neurological abnormality
• Decreased variability is non-reassuring unless
  caused by sleep or administration of drugs

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Nursing Care Decreased Variability

• Rule out non hypoxic causes
• Stimulate the fetus
• Change maternal position
• If in labour
• O2 by mask at 8L/min
• Increase IV rate and d/c oxytocin if infusing
• Notify physician, document time, description and
  tx

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Periodic and Non-periodic (episodic) Changes

• Four types
• accelerations
• early decelerations
• late decelerations
• variable decelerations

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Accelerations

• 32 weeks and more
• Abrupt increases in the FHR of at least 15 bpm
  above the baseline persisting for at least 15
  seconds and less then 2 minutes before returning
  to baseline (Prolonged acceleration increase in
  FHR lasts for 2-10 minutes)
• Before 32 weeks
• Accelerations are defined as FHR greater than 10
  bpm above the baseline for a duration of greater
  than 10 seconds
• Response of a healthy fetus to cardiovascular
  stimuli
• Compression of umbilical vein but not artery
• Accelerations do not have to be related to fetal
  movement and absence does not necessarily
  indicate fetal compromise

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Decelerations

• Decelerations are transient decreases of the
  fetal heart from the baseline
• Early decelerations
• Late decelerations
• Variable decelerations
• Prolonged decelerations
• Evaluate
• Frequency
• Duration
• Persistence over time
• Lowest heart rate within the deceleration
• Relationship with uterine activity

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Early Decelerations

• Uniform in shape
• Onset and offset match the contraction (mirror
  image)
• Depth reflects intensity of the contraction
• Variability unaffected not non-reassuring
• Clinical situations vaginal exams, with pushing,
  electrode attachment, CPD, cephalic
  presentations, after rupture of membranes

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Early Decelerations - Nursing Care

• No treatment may be necessary
• Manage the clinical situation as warranted
• Continue to monitor the fetal heart
• Watch for any changes
• Document deceleration, baseline rate, variability
  and presence of accelerations

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Late Decelerations

• Transitory decreases in FHR caused by
  uteroplacental insufficiency and reflect fetal
  hypoxia
• Non-reassuring no matter how little the HR drops!
• Uniform in shape, mirror image, may be very
  shallow
• Often loss of variability
• Usually begins after the onset of the contraction
  and always ends after the contraction
• Clinical situations placental dysfunction,
  hypotension-bleeding, uterine hyperstimulation)

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Late Decelerations Nursing Care

• Alter patient position left side
• Turn off oxytocin
• Oxygen at 8L/min per mask
• Correct hypotension
• Do vaginal exam
• Notify physician
• Document time, description, treatment and response

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Variable Decelerations

• Variable in shape abrupt drop and return
• Variable in onset and offset
• Variable in depth (usually gt 15 bpm)
• Variable in duration (gt15 seconds and lt 2
  minutes)
• Normal or altered variability
• Caused by compression of umbilical cord
• Ominous development
• Clinical situation late in labor, compression
  caused by descent, nuchal cord, prolapsed cord,
  occult cord (partially prolapsed),
  oligohydramnios

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Prolonged Deceleration

• Decelerations below the baseline that last more
  than 2 minutes and less than 10 minutes
• Causes
• Decreased Blood Flow
• Cord compression
• Maternal hypotension
• Uterine hypertonus
• Paracervical administration of caine meds
• Prolonged vagal response
• Vigorous scalp stimulation
• Second stage head compression

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Variable/Prolonged Decelerations Nursing Care

• Change maternal position
• Give O2 by mask at 8L/min
• Decrease uterine activity/turn off oxytocin
• Assess for cord prolapse vag exam
• Establish IV access and give fluid
• Notify physician
• Document!

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Interpreting and Documenting NSTs

• Use a systematic approach
• Refer to the various components
• baseline FHR
• variability
• accelerations
• decelerations
• uterine activity
• Provide interpretation such as reactive or
  non-reactive
• (reassuring or non-reassuring if patient is in
  labour)

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Reactive NST

• Reactive non stress test has
• tracing is at least 20 minutes
• Baseline FHR is within normal range
• Variability is between 6 and 25 bpm
• 2 or more FHR accelerations within 20 minutes
  that meet the criteria for the gestational age