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Fetal Health Surveillance

Fetal Health Surveillance. Electronic Fetal Monitoring Susan Schank Regional Education Services 2005. Aim of Intrapartum Fetal Surveillance. Why do we do fetal monitoring?

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Fetal Health Surveillance

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  1. Fetal Health Surveillance Electronic Fetal Monitoring Susan Schank Regional Education Services 2005

  2. 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)

  3. 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)

  4. 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)

  5. 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

  6. 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

  7. 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

  8. Purpose of aNST • 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

  9. 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 Who should have a NST?

  10. 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

  11. 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 woman’s fundus must be palpated to determine the intensity of the contractions • Baseline Tone – refers to the relaxation of the uterus between contractions.

  12. 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 >) • Interval between periodic changes, contractions, and fetal movement (120 – 160 bpm for 28-32 weeks)

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

  14. 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!

  15. 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

  16. Variability • Variability classified as: • Absent – amplitude of variability not detectable • Minimal – amplitude detectable but < 6 bpm • Moderate – amplitude ranges from 6-25 bpm • Increased – amplitude is >25 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

  17. 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

  18. Periodic and Non-periodic (episodic) Changes • Four types: • accelerations • early decelerations • late decelerations • variable decelerations

  19. 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

  20. 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

  21. 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

  22. 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

  23. 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)

  24. 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

  25. Variable Decelerations • Variable in shape – abrupt drop and return • Variable in onset and offset • Variable in depth (usually > 15 bpm) • Variable in duration (>15 seconds and < 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

  26. 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

  27. 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!

  28. Interpreting and Documenting NST’s • 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)

  29. 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

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