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FETAL HEART RATE TRACING

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FETAL HEART RATE TRACING Powered By Docstoc
					ELECTRONIC FETAL
   MONITORING
 By: Dr. Sahar Al-Suwailem
 Consultant GYN endoscopy
         KFMC, WSH
              Introduction
Stillbirth rate (fetal death rate). The number of
stillborn infants per 1000 infants born, including live
births and stillborns
Neonatal mortality rate. The number of neonatal
deaths per 1000 live births
Perinatal mortality rate. The number of stillbirths
plus neonatal deaths per 1000 total births
Infant mortality rate. The number of infant deaths
per 1000 live births
   Introduction - cont.
Introduced in 1960 at Yale university with the
aim of reduction in cerebral palsy
No reduction and rate is still 2-3/10000 live
births (Parkes et al 2001)
FHR by NST is most common test of fetal well
being
NST should not be relied upon as the sole
means of establishing fetal well being (I A)
          Cerebral Palsy
Definition - a chronic neuromuscular disability
characterized by aberrant control of
movement or posture appearing early in life
and not the result of recognized progressive
disease. It may be accompanied by a seizure
disorder or mental retardation or both
Causes Unknown
   Cerebral Palsy - cont.
The largest study of risk factors associated
with cerebral palsy did not confirm a strong
relationship between perinatal asphyxia and
cerebral palsy
10% of cerebral palsy in term infants is
associated with perinatal asphyxia
   Introduction -cont.
Despite widespread use
   There is controversy about the efficacy of
   EFM
   Interpretation of fetal heart rate patterns
   Reproducibility of its interpretation
   Management algorithms for abnormal or
   non reassuring patterns
What are the criteria's of ideal test
       of fetal well being?
 Quick
 Easy to perform
 Yield readily interpreted results that are reproducible
 Clearly identify the compromised fetus at a stage at
 which intervention will improve the outcome
 It should not give an abnormal result for a healthy
 fetus
 UNFORTUNATELY this ideal test does not yet exist
Appropriate emergency nursing
        interventions
Change maternal position
Give oxygen per mask @ 8-10 liters
Initiate or increase intravenous fluids
(plasma expander such as ringer lactate)
Discontinue oxytocin, remove
prostaglandin if possible
Vaginal examination
   Monitoring Variables
FHR- EXTERNAL MONITORING
MODES-USS (movement of fetal heart)
PHONOCARDIOGRAPHY( heart sounds)
ABDOMINAL WALL FECG (Best indirect
signal source)
INTERNAL MONITORING
SIGNAL SOURCE (electrical activity of
FHR)
Factors Affecting Test Results
SLEEP CYCLES (20-40 MIN)
MEDICATIONS
 EPIDURAL ANALGESIA
 PARENTRAL NARCOTICS
 EFFECT OF STEROIDS
 (BETAMETHASONE) transiently decrease the
 FHR variability returned by 4-7 days and decrease
 in acceleration
 NO EFFECT OF DEXAMETHASONE
 MGSO4
Factors Affecting Test Results -
             cont.
MATERNAL SMOKING
MATERNAL HYPOGLYCEMIA
PREMATURITY - non reassuring FHR patterns
may occur with up to 60 % of preterm parturient
with most common abnormality being deceleration
and bradycardia followed by tachycardia and flat
tracing
Variable decelerations more common among
preterm (55-70%) than term (20-30%)
Uterine Activity
Interpretation of EFH monitoring
 Baseline
 Baseline variability
 Accelerations
 Deceleration     Early
                  Late
                  Variable
                  Prolonged
 Tachycardia / Bradycardia
Interpretation of EFH monitoring -
               cont.

Baseline – the mean FHR rounded to increments of
5 beats per min during a 10 min segment excluding:
      Periodic or episodic changes
      Periods of marked FHR variability
      Segments of baseline that differ by more
      than 25 beats/minute
The baseline must be for a minimum of 2 minutes in
any 10 minute segment
        Baseline Variability
Definition – fluctuations in the baseline FHR due to the
beat to beat changes (R-R interval differences)
between each computed heartbeat
Spiral electrode give accurate variability assessment
Classification:
       Absent
       Minimal – < 5 bpm
       Moderate – 6 to 25 bpm
       Marked – > 25 bpm
Average to Increased Variability
Decreased Variability
         Types of Variability

Short                 term             variability:
It reflects the beat to beat changes due to the
interval difference between each successive heart
beat of the ECG signal
Long                term                variability:
Describes the cycling effect of FHR over time, this
changes are described in terms of frequency per
                      minute
2-6 cycles/minute with an amplitude of change of
6-10 beats being average
      Causes of Decreased
    Variability or Silent Pattern

Fetal sleep
Drugs (sedatives, tranquilizers, narcotics)
Prematurity
Tachycardia
Congenital anomalies (CNS)
HYPOXIA
         Saltatory variability more than 40 minutes
High sympathetic tone
Cord compression with: Acceleration during contractions
                        Mixed cord compression pattern
                 Accelerations

A visually apparent increase in the FHR from the most
recently calculated baseline
  32 wks: an ACME of 15 bpm above baseline, with
the duration of 15 sec but <2 minutes
  32 wks: an ACME of       10bpm with the duration of
10 sec but <2 minutes
Prolonged acceleration last    2 minutes but < 10
minutes
If acceleration lasts   10 minutes it is baseline changed
Accelerations with Normal Variability
   Classification of Acceleration
According to wave form and timing in relation to UC or FM
   Uniform accelerations
   Variable accelerations –Shoulders – variable
   accelerations that precede or follow variable
   decelerations associated with average baseline
   variability
   Merging accelerations
   Overshoot – smooth acceleration following a severe
   variable deceleration, usually lasts longer than 15
   seconds. Only acceleration pattern considered to be an
   ominous sign
Uniform Accelerations
Merging Accelerations
Variable Declarations followed by
          Accelerations
          (OVERSHOOTS)
                 Bradycardia
Baseline FHR <110 bpm
       Causes of Bradycardia

    Maternal                        Fetal
Hypotension         Fetal Hypoxia
Drug response       Umbilical cord compression
Maternal position   Fetal acidosis
Connective tissue   Fetal cardiac conduction or
disease             structural defect
Congenital heart    Vagal stimulation with chronic head
block (SLE)         compression (OP, OT position)
Characteristics of FHR
Deceleration Patterns
Early Decelerations
                   Physiology of early
                     decelerations
                           Early Decelerations



                          Pressure on fetal head


                         Alter cerebral blood flow


Head compression       Stimulus central vagus nerve


                    Produces decrease in heart rate with

                      Recovery occurring as pressure
                                is relived
Late Decelerations
      PHYSIOLOGY of PLACENTAL INSUFFICIENCY
 Uterine hyperactivity or             True placental dysfunction
  Maternal hypotension



   Decreases intervillous
  Space blood flow during
    Uterine contractions


            Decreases maternal / fetal oxygen transfer



  Activates vagal response                  Anaerobic metabolism



Produces cardio-deceleration                    Lactic acidosis
Variable Decelerations
Transitory umbilical cord compression

Collapses umbilical vein                          Producing fetal hypovolemia

Occludes umbilical                                 Transient cardioacceleration
artery/vein

Produces hemodynamic changes (hypotension from fetal outflow
of blood without return from placenta)


Activates baroceptors and chemoceptors

Stimulates vagus nerve

Produces cardiodeceleration

(reflective of baroceptor response
 to final hypotension with total occlusion

              If prolonged                           Produces hypoxia
          Variable Decelerations
ETIOLOGY:
Interruption in umbilical blood flow can result from
   1. Maternal position
   2. Short cord
   3. Nuchal cord, leg, arm or other body parts
   4. Knot in cord
   5. Prolapsed cord
   6. Fetal movement in presence of oligohydramnios
 Classification of variable
       deceleration

Reassuring
Non-reassuring with atypical features
         Atypical Features
Deceleration < 70 bpm lasting > 60 seconds
Loss of variability in baseline FHR and in the trough
of deceleration
Biphasic deceleration
Prolonged secondary acceleration (post deceleration
smooth overshoot of > 20 bpm increase or lasting >
20 seconds
Slow return to baseline
Continuation of the baseline at a lower level than
prior to the deceleration
The presence of fetal tachycardia
   Grading based on duration of Nadir
     Variable Decelerations Follows

     MILD             MODERATE         SEVERE
Any level for <30   <70bpm for 30-60 <70bpm for
seconds or 70 -     seconds or 70-80 >60seconds
80 bpm for          bpm for > 60
<60seconds or       seconds
more than 80bpm
for any duration
      Prolonged Decelerations
Drop in fetal heart rate lasting longer than 2 minutes
but <10mins from onset to return to baseline
Possible causes:
   Umbilical cord compression
   Hypertonic uterine activity
   Altered maternal condition e.g. hypotension,
   convulsion, respiratory arrest
   Procedures e.g. vaginal examination,
   paracervical block, FBS
Prolonged Decelerations
Prolonged Decelerations Recovery to Baseline
                  TACHYCARDIA
Baseline FHR >160bpm




        Tachycardia + late decelerations
Tachycardia + silent pattern + late
         decelerations
     Causes of Tachycardia
        MATERNAL                          FETAL
Fever                         Infection
Infection                     Prolonged fetal activity or
Dehydration                   stimulation
Hyperthyroidism               Chromic hypoxemia
Endogenous adrenalin or       Anemia
anxiety                       Cardiac abnormalities
Medication or drug response
Anemia
What Findings on EFM Reassured Fetal Status
     Reassuring Pattern
FHR accelerations generally shows
that the fetus is not acidemic
Normal variability is reassuring even in
the presence of late or variable
decelerations
Categorization of FHR Tracing
REASSURING PATTERN
      Baseline normal
      Variability normal
      Accelerations
      No decelerations
SUSPICIOUS TRACE
      One feature not normal
ABNORMAL TRACE
     Two features not normal
           Sinusoidal pattern
1. Baseline FHR in normal range
2. Predominance of long term variability
3. Absence of short term variability
4. Oscillations above and below the baseline have a
   sine wave shape with an amplitude of 5 to 15 bpm
   and frequency of 2-5 cycles per minute
5. No areas of FHR variability
Pseudosinusoidal Pattern
           Lambda Pattern
Common in early labor, consists of an
acceleration followed by deceleration and then
return to baseline associated with uterine
contractions, physiology unknown, don’t
confuse with late deceleration
Lambda Pattern
    Are there ancillary tests that
       reassure fetal status?
Allis clamp scalp stimulatio
Fetal scalp sampling
Vibro acoustic stimulation
Digital scalp stimulation
Each of these tests is a reliable method to
exclude acidosis if accelerations are noted after
stimulation
Summary of recommendations
     and conclusions
The false-positive rate of EFM for predicting adverse
outcomes is high
The use of EFM is associated with an increase in the
rate of operative interventions (vacuum, forceps, and
caesarean delivery
The use of EFM does not result in a reduction of
cerebral palsy rates
With persistent variable decelerations, amnioinfusion
reduces the need to proceed with emergent
caesarean delivery and should be considered
Part II - Fetal Blood Sampling
  Hypoxemi: Decreased oxygen content
            in blood
  Hypoxia: Decreased level of oxygen
            in tissue
  Acidemia: Increased concentration of
            hydrogen ions in the blood
  Asphyxia: Hypoxia with matabolic
            acidosis
Additional tests and therapies used in
       combination with EFM

   Units employing EFM should have ready
   access to fetal blood sampling facilities.
   Where delivery is contemplated because
   of an abnormal fetal heart-rate pattern,
   in cases of suspected fetal acidosis,
   fetal blood sampling should be
   undertaken in the absence of technical
   difficulties or any contraindications
Additional tests and therapies used in
   combination with EFM - cont.

   Contraindications to fetal blood sampling
   includes:
        Maternal infection (e.g. HIV, hepatitis viruses and
        herpes simplex virus)
        Fetal bleeding disorders (e.g. haemophilia)
        Permaturity (<34 weeks)
   Where there is clear evidence of acute fetal
   compromise (e.g. prolonged deceleration
   greater than three minutes), fetal blood
   sampling should not be undertaken and the
   baby should be delivered urgently
Additional tests and therapies used in
   combination with EFM - cont.

   Fetal blood sampling should be undertaken
   with the mother in the left-lateral position
   In the presence of abnormal FHR patterns and
   uterine hypercintractility (not secondary to
   oxytocin infusion) tecolysis should be
   considered. A suggested regimen is
   subcutaneous terbutaline 0.25 mg
   Classification of fetal blood
         sample results
Fetal blood sample       Subsequent action
(FBS) result (pH)*
>= 7.25                  FBS should be repeated if the FHR
                         abnormality persists
7.21 - 7.24              Repeated FBS within 30 minutes or
                         consider delivery if rapid fall since
                         last sample
<= 7.20                  Delivery indicated

* all scalp pH estimations should be interpreted taking into
account the initial pH measurement, the rate f progress in labour
and the clinical features of the mother and baby
Thank You

				
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