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ELECTRONICFETALMONITORS1
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MONITORINGTHEFETALHEARTRATE
External monitoring is performed using a
hand-held Doppler ultrasound probe to
auscultate and count the FHR during a
uterine contraction and for 30 secondsthereafter to identify fetal response.
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EXTERNALMONITORING
It may also be performed using an external
transducer, which is placed on the maternal
abdomen and held in place by an elastic belt or
girdle. The transducer uses Doppler ultrasound to
detect fetal heart motion and is connected to anFHR monitor. The monitor calculates and records
the FHR on a continuous strip of paper.
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INTERNALMONITORING
Is performed by attaching a screw-type electrode to
the fetal scalp with a connection to an FHR monitor.
The fetal membranes must be ruptured, and the
cervix must be at least partially dilated before the
electrode may be placed on the fetal scalp.
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INTERMITTENTVSCONTINUOUSAUSCULTATION
The American College of Obstetricians and Gynecologists(ACOG) states that with specific intervals, intermittentauscultation of the FHR is equivalent to continuous EFM indetecting fetal compromise.
ACOG has recommended a 1:1 nurse-patient ratio ifintermittent auscultation is used as the primary technique ofFHR surveillance.
The recommended intermittent auscultation protocol calls forauscultation every 30 minutes for low-risk patients in the activephase of labor and every 15 minutes in the second stage oflabor.
Continuous EFM is indicated when abnormalities occur withintermittent auscultation and for use in high-risk patients
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HIGH-RISKINDICATIONSFORCONTINUOUS
MONITORINGOFFETALHEARTRATE
Maternal medical illness:
Gestational diabetes
Hypertension
Asthma
Psychosocial risk factors
No prenatal care
Tobacco use and drug abuse
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HIGH-RISKINDICATIONSFORCONTINUOUS
MONITORINGOFFETALHEARTRATE
Obstetric complications
Multiple gestation
Post-date gestation
Previous cesarean section
Intrauterine growth restrictionPremature rupture of the membranes
Congenital malformations
Third-trimester bleeding
Oxytocin induction/augmentation of laborPreeclampsia
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BENEFITSANDRISKSOFEFM
Benefits:
1. to detect early fetal distress resulting from fetal
hypoxia and metabolic acidosis.
2. Closer assessment of high-risk mothers.Risks:
a) tendency to produce false-positive results.
b) fetal scalp infection and uterine perforation.
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NORMALPATTERNS
Normal rate: between 120 and 160 beats per
minute (bpm).
Short term variability (3-5 BPM)
Long term variability (15 BPM above baseline,lasting 10-20 seconds or longer)
Contractions every 2-3 minutes, lasting about 60
seconds
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FHR VARIABILITY
Loss of variability:
1. Prematurity: there is little rate fluctuation before 28weeks
Variability should be normal after 32 weeks
2. Fetal hypoxia
3. Congenital heart anomalies
4. Fetal tachycardia
5. May be uncomplicated and may be the result of
fetal quiescence (rest-activity cycle or behaviorstate), in which case the variability usuallyincreases spontaneously within 30 to 40 minutes
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Loss of variability:
Uncomplicated loss of variability may also be
caused by central nervous system depressants
such as morphine, diazepam (Valium) and
magnesium sulfate
Beta-adrenergic agonists used to inhibit labor, such
as ritodrine (Yutopar)
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TACHYCARDIA
>160 BPM
Most are not suggestive of fetal jeopardy
Associated with:
Fetal hypoxia Maternal fever
Hyperthyroidism
Maternal or fetal anemia
Drugs: Atropine ,Ritodrine (Yutopar) Chorioamnionitis
Fetal tachyarrhythmia
Prematurity 13
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BRADYCARDIA
Bradycardia in the range of 100 to 120 bpm ( mild)
1. not associated with fetal acidosis.
2. common in post-date gestations
3. in fetuses with occiput posterior or transverse presentations.
Bradycardia less than 100 bpm occurs in:
a) fetuses with congenital heart abnormalities
b) myocardial conduction defects
Moderate bradycardia of 80 to 100 bpm is a nonreassuring
pattern. Severe prolonged bradycardia of less than 80 bpm that lasts
for three minutes or longer is an ominous finding indicatingsevere hypoxia and is often a terminal event.
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CAUSESOFSEVEREFETALBRADYCARDIA
Prolonged cord
compression
Cord prolapse
Tetanic uterinecontractions
Paracervical block
Epidural and spinal
anesthesia
Maternal seizures
Rapid descent Vigorous vaginal
examination
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BRADYCARDIA
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LATEDECELERATIONS
Associated with uteroplacental insufficiency and areprovoked by uterine contractions.
Any decrease in uterine blood flow or placental
dysfunction Maternal hypotension
Uterine hyperstimulation may decrease uterine bloodflow.
Postdate gestation
Preeclampsia
Chronic hypertension and diabetes mellitus
Maternal conditions such as acidosis and hypovolemia(DKA) 18
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EARLYDECELERATIONS
Caused by fetal head compression during uterine
contraction, resulting in vagal stimulation and
slowing of the heart rate.
Has a uniform shape, with a slow onset that
coincides with the start of the contraction and a
slow return to the baseline that coincides with the
end of the contraction.
It has the characteristic mirror image of the
contraction
These decelerations are not associated with fetal
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VARIABLEDECELERATIONS
Variable in onset, duration and depth
May occur with contractions or between them
Sudden onset/recovery
Variable decelerations are shown by an acute fall inthe FHR with a rapid downslope and a variable
recovery phase.
They are variable in duration, intensity and timing.
They resemble the letter "U," "V" or "W" and maynot bear a constant relationship to uterine
contractions
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SEVEREVARIABLEDECELERATIONS
Most common pattern during labor
In patients who have experienced premature rupture of
membranes
and decreased amniotic fluid volume.
Variable decelerations are caused by compression of the
umbilical cord.
Pressure on the cord initially occludes the umbilical vein,
which results in an acceleration and indicates a healthyresponse. This is followed by occlusion of the umbilical
artery, which results in the sharp downslope.
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SIGNSOFNONREASSURINGVARIABLE
DECELERATIONSTHATINDICATEHYPOXEMIA
Increased severity of the deceleration
Late onset and gradual return phase
Loss of "shoulders" on FHR recording
A blunt acceleration or "overshoot" aftersevere deceleration
Unexplained tachycardia
Late decelerations or late return to baselineDecreased variability
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PROLONGEDDECELERATIONS
Last > 60 seconds
Occur in isolation
Associated with: Maternal hypotension
Epidural
Paracervical block
Tetanic contractions Umbilical cord prolapse
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NONREASSURINGANDOMINOUSPATTERNS
Fetal tachycardia
Fetal bradycardia
Saltatory variability
Variable decelerations
associated with a
nonreassuring pattern
Late decelerations with
preserved beat-to-beat
variability
Persistent late decelerationswith loss of beat-to-beatvariability
Nonreassuring variabledecelerations associated withloss of beat-to-beat variability
Prolonged severebradycardia Sinusoidalpattern
Confirmed loss of beat-to-beat variability not associatedwith fetal quiescence,medications or severeprematurity
Nonreassuring patterns Ominous patterns
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EMERGENCYINTERVENTIONSFOR
NONREASSURINGPATTERNS
Call for assistance
Administer oxygen through a tight-fitting face mask
Change maternal position (lateral or knee-chest)
Administer fluid bolus (lactated Ringer's solution)Perform a vaginal examination and fetal scalp
stimulation
When possible, determine and correct the cause of
the pattern Consider tocolysis (for uterine tetany or
hyperstimulation)
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EMERGENCYINTERVENTIONSFOR
NONREASSURINGPATTERNS
Discontinue oxytocin if used
Consider amnioinfusion (for variable
decelerations)
Determine whether operative intervention iswarranted and, if so, how urgently it is
needed
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