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Prepared by Helen Cooke

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Title: Prepared by Helen Cooke


1
Intrapartum Fetal Heart Rate Monitoring
Prepared by Helen Cooke Warwick Giles February
2008
2
Goals
  • Who should be monitored
  • Tools for intrapartum monitoring
  • Describe the parameters for intrapartum assessment

3
FHR as a screening test
  • Intrapartum FHR monitoring is a screening test
    that provides information to alert the clinician
    that a true test for fetal welfare assessment
    needs to be performed, eg
  • An atypical variable (pathological feature)
  • fetal blood sampling should be performed

4
Documentation
  • At commencement of the CTG the documentation of
    the pattern should include
  • womans name and MRN,
  • estimated gestational age,
  • clinical indications for performing the FHR
    pattern,
  • time and date of commencement and
  • maternal pulse rate.
  • The outcome of the FHR pattern should be
    documented both on the CTG and in the womans
    medical records at least every ½ hourly
    throughout labour.

5
FHR evaluation
  • Dr C Bravado ? ALSO
  • DR determine the risk
  • C contractions
  • Bra baseline rate
  • V variability
  • A accelerations
  • D decelerations
  • O overall assessment (followed by a management
    plan)

6
FHR Monitoring on admission in labour
  • ??? Electronic FHR monitoring
  • ??? Doppler auscultation
  • ??? Pinards

7
Considerations for which form of monitoring to
use on admission
  • Has the woman had good antenatal care?
  • Are you aware of the fetal welfare and
    development?
  • Are there any risk factors present?
  • Is the woman in labour?

8
Admission CTGs
  • Are a poor predictor of fetal compromise during
    labour in low risk women
  • There is no current evidence that supports
    routine CTG testing on admission in low risk
    women is therefore not recommended
  • Rationale was that this would identify a sub
    group of fetus who would benefit from intensive
    surveillance RCOG
  • Make an assessment of the risks to determine
    whether electronic FHR monitoring is required

9
Who should have continuous electronic FHR
monitoring?
  • Antenatal risk factors
  • Prematurity
  • Pre-eclampsia/eclampsia
  • Diabetes
  • Growth restriction
  • Non-reassuring antenatal fetal welfare assessment
  • Multiple pregnancy
  • Malpresentation

10
Who should be have continuous electronic FHR
monitoring?
  • Intrapartum factors
  • Syntocinon
  • Meconium
  • Epidural
  • Suspicious FHR on auscultation
  • Prolonged rupture of the membranes
  • Prematurity
  • Previous C/S

11
Practice Recommendations for intermittent
auscultation
  • Healthy women with uncomplicated labour IA with
    Pinards/Doppler recommended
  • Active labour- after contraction for at least 60
    seconds at least
  • every 15mins 1st stage
  • every 5mins 2nd stage
  • Continuous EFM is recommended if
  • Baseline lt 110 or gt160bpm
  • Decelerations or intrapartum risk factors develop

12
Is the woman established in labour?
  • The interpretation of the FHR pattern should be
    considered in context.
  • If the woman is not established in labour is
    reactivity present?

13
Guidelines
  • Education based on Royal College of Obstetrics
    and Gynaecology (RCOG) Guidelines
  • The Use of Electronic Fetal Monitoring
  • www.rcog.org.uk
  • RCOG provide clear descriptions that will provide
    a consistent approach to interpretation

14
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15
Lactate of gt 6 pathological
16
Categorisation of FHR Features
17
Categorisation of FHR Patterns
18
Baseline rate
  • Normal 110 160bpm
  • Bradycardia (moderate) 100 109bpm
  • Bradycardia (abnormal) lt 100 bpm
  • Tachycardia (moderate) 161 180 bpm
  • Tachycardia (abnormal) gt180 bpm
  • (RCOG)

19
Baseline Rate
20
Baseline Bradycardia
  • Bradycardia (moderate) 100 109bpm
  • Bradycardia (abnormal) lt 100 bpm
  • Rare
  • Consider the cause if this is a sudden event ?
    prolonged deceleration

21
Causes of Baseline Tachycardia
  • Excessive fetal movement
  • Maternal dehydration
  • Prematurity
  • Maternal fever
  • Maternal or fetal stress causing adrenaline
    release
  • Chorioamnionitis

22
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23
Tachycardia
  • Also seen with fetal asphyxia (low levels of O2)
    particularly in the early stages
  • In the presence of true asphyxia, tachycardia is
    most commonly associated with other features such
    as decreased variability

24
Variability
  • Greater than 5bpm and less than 25bpm
  • Increased variability is often seen following an
    acute hypoxic event.
  • Should settle after about 10 mins when the fetus
    returns to normal O2 levels

25
Saltatory
Saltatory
26
Causes of Reduced Variability
  • 5bpm fetal sleep or quiet state
  • Maternal medications Morphine, Pethidine etc
  • Fetal hypoxia depressing the CNS
  • Fetal anomalies
  • Fetal Cardiac Arrhythmias

27
Sinusoidal
  • Wave like pattern of 3 5 oscillation / min
    ranging between 5 15 beats

28
Accelerations
  • Not always present in the intrapartum pattern as
    the most common feature is a deceleration
  • A reassuring feature of an intrapartum pattern
  • Spontaneous acceleration pH gt7.25

29
Decelerations
  • Early
  • Late
  • Variable typical and atypical
  • Prolonged

30
Early
  • Repetitive from one contraction to another
  • Recovery to baseline is always at the end on the
    contraction
  • Caused by vagal nerve stimulation

31
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32
The Fetal Heart Rate Early decelerations
  • Begin with head compression during the
    contraction
  • This reduction of cerebral blood flow leads to
    hypoxia and hypercapnia
  • Hypercapnia leads to hypertension with triggering
    of baroreceptors
  • Results in bradycardia mediated by
    parasympathetic nervous system (via the vagal
    nerve)
  • Fall in FHR is matched to rise in contraction
    strength
  • Not indicative of fetal compromise

33
Late Decelerations
  • Repetitive from one contraction to the next (3 or
    more)
  • Recovery to baseline is late, well after the end
    of the contraction
  • More ominous when associated with minimal
    variability ? baseline
  • Reflects a change in placental ability to
    adequately meet fetal needs
  • May indicate the presence of fetal hypoxia and
    acidosis
  • Often signifies fetal decompensation

34
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36
The Fetal Heart Rate Late decelerations
  • Lates represent fetal hypoxia and are related to
    an interruption in O2 supply at cardiac level
  • Reduced O2 leads to stimulation of chemoreceptors
  • Results in activation of the cardiac centres in
    the brainstem
  • SA node is effected and the FHR slows.
  • With the prolonged hypoxia, myocardium is
    effected causing further decrease in the FHR and
    hypotension
  • Recovery is slower as the myocardium gradually
    reoxygenates

37
Variable Decelerations
  • Repetitive or intermittent
  • Often mimic letters of the alphabet
  • U V W M
  • Rapid sudden fall in FHR
  • Often rapid recovery
  • Reflect some degree of umbilical cord impingement
  • Often seen when liquor volume is ?

38
Typical Variable - causes
  • Compression of blood in umbilical vein results in
    loss of circulating blood volume causing a well
    fetus to have a primary acceleration
    demonstrated by ? autonomic NS activity
    (1stshoulder)
  • Followed by partial compression or stretching of
    the umbilical arteries causing blood flow
    interruption and the deceleration.
  • This decreases blood flow to the Rt heart causes
    hypotension
  • This stimulates the sympathetic nervous system
    and catecholamine release
  • Causing a compensatory fetal tachycardia
    following the deceleration (the 2nd shoulder).

39
Typical Variable - features?
  • A sharp V shaped deceleration caused by
    compression of blood in umbilical arteries
    preceded and followed by an acceleration
    (shoulder)
  • The classic typical variable due to a transient
    occlusion of the umbilical cord for such a short
    duration that the period of hypoxia is not enough
    to effect the previously well fetus

40
Shoulders
  • Baseline Rate

Typical variables
41
Atypical Variable Decelerations
  • Loss of primary or secondary rise in baseline
    rate (No Shoulders)
  • Slow return to baseline FHR after the end of the
    contraction
  • Prolonged increase or secondary rise in baseline
    rate (Overshoot)
  • Biphasic deceleration (Variable followed by late
    component)
  • Loss of variability during a deceleration
  • Continuation of the baseline rate at a lower level

42
Slow return to baseline
  • Concerning feature
  • Associated with low Apgar scores and fetal
    hypoxia
  • 47 of fetuses will have a one min Apgar score lt
    7 however, only 10 have a five min Apgar lt 7
  • Can be improved by inutero resuscitation
  • Need to look for other non-reassuring features

43
Does not return to baseline
Slow return
Baseline Rate
There is very little time where the FHR returns
to baseline rate
1cm per min
44

Slow or no return to baseline
Baseline
1cm per min
45
Overshoot
Baseline Rate
1cm per min
46
Prolonged Decelerations
  • FHR falls for gt 3 minutes
  • Usually associated with an acute insult - Top up,
    VE, ? Syntocinon
  • FHR pattern before and in recovery indicates
    fetal tolerance - not the deceleration itself
  • Should be managed vigorously

47
Suspicious FHR Pattern What should you do?
  • Maternal
  • Position
  • Dehydration
  • Infection
  • Hypotension
  • ?V.E/bedpan
  • Vomiting/vasovagal
  • Analgesia/Drugs
  • Mechanical
  • Poor quality CTG
  • Maternal pulse
  • Transducer site
  • FSE
  • Oxytocics
  • Prostaglandins

48
Pathological What should I do?
  • Roll woman into L) lateral
  • Perform Fetal Blood Sampling
  • If pH ?7.25 repeat within one hour if the FHR
    abnormality persists
  • If pH 7.21-7.24 repeat within 30mins or deliver
    if rapid fall since last FBS
  • If pH lt 7.20 DELIVER immediately
  • Lactate 4.2 - 4.8 DELIVER.
  • All FBS should take into account previous pH,
    rate of progress clinical information

49
Abnormal FBS results
  • Expedite delivery
  • Mother consent
  • Urgency should be dictated by severity of FHR
    abnormality maternal factors
  • Reasons FBS not appropriate
  • maternal or fetal infection
  • Fetal bleeding disorders
  • Prematurity lt 34 weeks

50
Conclusion
  • Earlies are caused by vagal nerve stimulation
  • Variables are caused by cord compression
  • Lates are caused by placental blood flow
  • Increasing heart rate and decreased variability
    are non-reassuring and worthy of concern

51
References
  • RCOG 2001 The Use of Electronic Fetal Monitoring
  • www.rcog.org.uk
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