welcome ctg + physiology training
DESCRIPTION
Why now? Funding from CCG – ? time limited Reduction in unplanned term admissions to NICU Reduction in hypoxic ischaemic encephalopathy Other potential benefits – fewer emLSCS, fewer instrumental deliveries Better teamwork through a unified approach to CTG interpretationTRANSCRIPT
Welcome CTG + PHYSIOLOGY TRAINING Why now? Funding from CCG ?
time limited
Reduction in unplanned term admissions to NICU Reduction in hypoxic
ischaemic encephalopathy Other potential benefits fewer emLSCS,
fewer instrumental deliveries Better teamwork through a unified
approach to CTG interpretation CCG Rationale : NHS Outcomes
framework
consistent with two domains: Domain one Preventing people from
dying prematurely Domain five Treating and caring for people in a
safe environment Also Litigation Failure to recognise an abnormal
CTG and act on it, or refer appropriately, is a major source of
litigation Growing number of litigants citing unnecessary caesarean
sections, instrumental deliveries Regular testing for midwives is
not yet a national requirement on the way Objectives for today ie
How is the baby?
A greater, evidence based, understanding of: fetal/maternal
physiology driving CTG/IA readings hypoxia the different causes and
their management CTG feature analysis rather than pattern
recognition the personal and organisational barriers to change the
importance of asking the RIGHT question ie How is the baby?
Guidelines will be referred to but this is not guideline training
NICE GUIDELINES 2014 Baseline Baseline Variability
Decelerations
Baseline Baseline Variability Decelerations Normal/Reassuring bpm 5
or more None or early Non Reassuring bpm 10 minutes Variability
>5 < minutes < 5 for more than 90 minutes Accelerations
Present Uncertain significance Decelerations None Typical variable
deceleration with over 50% of contractions for over 90 minutes.
Single prolonged deceleration for up to 3 minutes Atypical variable
decelerations for over 50% of contractions or Late deceleration for
over 30 minutes. Single prolonged deceleration for over 3 minutes
FIGO GUIDELINES 2015 Normal Suspicious Pathological Baseline
Normal Suspicious Pathological Baseline bpm Lacking at least one
characteristic of normality but with no pathological features 30
min or 20 min if reduced variability, or one prolonged deceleration
>5 min (Points to consider) Baseline
Preterm fetus towards upper end of range and post term towards
lower end Tachycardia Above 160 lasting >10 minutes Bradycardia
Baseline 10 minutes Variability Normal bandwidth: 5-25bpm Reduced
variability: A bandwidth amplitude below 5bpm for more than 50
minutes in baselinesegments or for more than 3 minutes during
deceleration Increased variability:Bandwidth exceeding 25bpm for
>30 minutes Decelerations Variable decelerations: (v-shaped)
rapid drop, good variability and rapid rise to baseline. Varying
size, shape and in relation to uterine contraction. Rarely
associated with fetal hypoxia/acidosis unlessevolve to exhibit
u-shaped component, reduced variability within deceleration or
individual duration lasts >3 minutes (baro) Late decelerations:
(u-shaped) and or/with reduced variability. Gradual onset and
gradual return to baseline (more than 30 seconds elapses between
beginning/end and its nadir (chemo) The underlying cause for the
appearance of the pattern can frequently be identified and the
situation reversed with subsequent recovery of adequate fetal
oxygenation. Etc etc.. Intermittent Auscultation
Homerton Guidelines- INITIAL ASSESSMENT- Risk assessment undertaken
including fetal movements, maternal observations as well as
existing risk factors Abdominal palpation Baseline of the FH to be
assessed by listening for at least a minute in between contractions
Contraction palpated and FH auscultated immediately following to
exclude deceleration Palpate maternal pulse to differentiate
between the two FIRST STAGE OF LABOUR- FH must be auscultated every
15 minutes for a minimum of 1 minute immediately after a
contraction Recorded as a single number SECOND STAGE OF LABOUR- FH
auscultated every 5 minutes, immediately after a contraction for 1
minute NICE Guidelines- As above CTG was developed: initially as a
screening tool to predict fetal hypoxia to enable obstetricians and
midwives to analyse the change of fetal heart rate.during labour to
institute timely intervention to avoid intrapartum
hypoxic-ischaemic injury Introduced into clinical practice approx
45 years ago
first guidelines appeared 1980s the aim of defining combinations of
features to help predict fetal hypoxia the false positive rate is
high, conservatively >60% no demonstrable improvement in the
rate of cerebral palsy or perinatal deaths (stable over last 50
years) significant increase in intrapartum caesarean section and
instrumental delivery rates So existing guidelines employ visual
interpretation of CTG
based on pattern recognition fraught with inter- and intra-observer
variability clinicians should NOT rely purely on guidelines
clinicians need to understand and respond to the physiology behind
fetal heart rate changes ie HOW IS THE BABY? As we will see, the
relationship between fetal oxygenation and neurological injury is
complex
CTG introduced with the expectation that it would significantly
reduce the incidence of injury CTG positively associated with
reduction in neonatal seizures Now apparent that most cases of (eg)
cerebral palsy are unrelated to intrapartum events prematurity,
infection greater threat(Fahey 2005 etc, etc) However a significant
minority of such cases may be related to intrapartum events and
therefore potentially avoidable A physiology based approach to CTG
would: improve perinatal outcomes reduce unnecessary operative
procedures reduce the need for additional tests of fetal well-being
While avoiding adverse fetal outcomes related to hypoxia/acidosis
is the main objective of intrapartum fetal monitoring, it is
equally important that it does not result in unnecessary obstetric
intervention, as some of these procedures, such as instrumental
vaginal delivery and caesarean delivery, are associated with
increased maternal and fetal risks. Ayres-de-Campos, D.,
Arulkumaran, S. (2015) Do not make any decision about a womans care
in labour on the basis of cardiotocography findings alone NICE 2015
(new) When interpreting CTG traces it is ESSENTIAL
to individualise each fetus and to analyse the CTG features
together with the clinical picture Before starting CTG
monitoring:
give a clear explanation of the rationale and process gain, and
record, consent MANDATORY to check and record maternal pulse use
Sonicaid or Pinard to establish FHR/position lateral, recumbent,
half-sitting, upright position supine /recumbent = aortocavel
compression = reduced placental perfusion and fetal oxygenation Do
not perform CTG for low risk woman in established labour
NICE 2015 HUH guidelines allow for maternal request on the
understanding that this may increase the risk of unnecessary
interventions Describe Risk /Define Rationale
Examples? See guidelines At the outset How is the mother? How is
the baby? By definition CTG suitability = at risk Remember this
when analysing features Contractions Will be referred to later but
rule of thumb, effective reoxygenation of fetus requires: seconds
between contractions, spontaneous labour 2.3 mins (138 seconds)
between contractions if syntocinon augmentation Movement Good fetal
movement gold standard of fetal wellbeing
Very significant if chronic hypoxia suspected Baseline the mean FHR
excluding accelerations and decelerations maintained by fetal
myocardium analysed over mins, expressed in bpm regulated by
autonomic nervous system (ie sympathetic/parasympathetic covered in
variability) influenced by gestation higher in preterm, as
parasympathetic less well developed 160 bpm >10mins = baseline
tachycardia
maternal tachycardia due to pyrexia/dehydration recent VE fetal
arrythmia (rare) chronic hypoxia if seen with reduced
variability/shallow decelerations Baseline Consider: 10 mins =
baseline bradycardia
with accelerations, absence of decelerations, good variability may
reflect post maturity heart defects sympatholytic drugs eg
antihypertensives maternal hypothermia acute hypoxia to myocardium
Variability bandwidth variation of baseline, after excluding
accelerations/decelerations maintained by the interaction between
the sympathetic and parasympathetic nervous systems sympathetic
fight or flight the accelerator parasympathetic calm and balm the
brake Therefore, the presence of good baseline variability gives
information about the integrity of the autonomic nervous system and
by extension, the brain. Normal variability is unlikely to be
associated with cerebral hypoxia Variability Consider: association
with drugs (CNS depressants)
3mins in decels) Consider: association with drugs (CNS depressants)
congenital anomalies infection hypoxia/acidosis in the CNS (brain)
periods of fetal sleep Fetal sleep? was the CTG normal prior to the
period of reduced variability? is cycling present ie periods of
normal variability, periods of reduced variability the combination
of these patterns is cycling cycling is a reassuring feature of
fetal well-being REDUCED VARIABILITY REDUCED VARIABILITY
Correlation with the FULL clinical picture is essential to perform
a differential diagnosis
High degree of subjectivity in the visual evaluation of a reduced
baseline careful re-evaluation necessary Ayres-de-Campos et al 2015
FIGO guidelines Variability >25 bpm = saltatory pattern
Not referred to in NICE guidelines (or HUH) Saltatory pattern exact
mechanism still debated
may be associated with rapidly evolving hypoxia usually with active
maternal pushing or the use of syntocinon infusion ? reflects
attempts by the autonomic nervous system to maintain stable
baseline when there is rapidly evolving hypoxic stress immediate
action to relieve stress and improve fetal oxygenation stop
pushing, stop syntocinon, consider tocolytic Variability
Accelerations transient increase in baseline
>15 bpm >15 secs, return to normal baseline caused by somatic
nervous system part of the peripheral nervous system responsible
for voluntary and reflex movement associated with fetal movement
two or more in 20 mins a reassuring feature, suggestive of fetal
well being if absent in early labour query presence of cycling
Accelerations Absent in presence of: fetal sleep drugs, eg
pethidine
infection chronic hypoxia, intrauterine fetal stroke
decreased/absent as labour progresses/2nd stage The erroneous
monitoring of maternal heart rate may result in accelerations of
greater magnitude and/or duration coinciding with uterine
contractions Decelerations a caution
The NICE guidance mentions several reasons for the limited value of
CTG in predicting fetal acidaemia. But the most important reason
has been omitted which is that all the previous studies use very
differing definitions of FHR decelerations and hence are not
comparable. Also, that unphysiological categorisation of FHR
decelerations would be a wrong foundation for any system of
interpretation BMJ editorial June 2014 ieHow is the baby?
Decelerations transient decrease in FHR >15 bpm >15
secs
reflex response of the fetus to ongoing hypoxic or mechanical
stress in labour protection against fetal stroke (variable)
protection against hypoxic injury to fetal myocardium (late)
guidelines classify as early, late, variable- in reality a
combination can occur as uterine contractions may compress fetal
head and umbilical cord at the same time Early Decelerations (