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 (