1. Introducing Fetal ECG waveform analysis for Intrapartum Care
S Arulkumaran
Professor & Head – Obstetrics & Gynaecology
St.George’s Hospital Medical School
University of London

2. Fetal Hypoxaemia > Hypoxia > Asphyxia
How to prevent fetal hypoxia?
Diagnose hypoxia
Institute corrective measures
Deliver
Fetal Hypoxaemia > Hypoxia > Asphyxia

3. Fetal response to hypoxemia
more effective uptake of oxygen
Reduced activity
decrease in growth rate
maintained energy balance
Oxygen saturation
Hypoxemia
Hypoxia
Asphyxia
Days and weeks
Hours
Minutes
Time

4. The fetal response to hypoxia
surge of stress hormones
redistribution of blood flow
anaerobic metabolism in the peripheral tissues
maintained energy balance
Oxygen saturation
Hypoxemia
Hypoxia
Asphyxia
Days and weeks
Hours
Minutes
Time

5. Fetal response to asphyxia
Alarm reaction
anaerobic metabolism in peripheral tissues
brain and heart organ
failure
Oxygen saturation
Hypoxemia
Hypoxia
Asphyxia
Days and weeks
Hours
Minutes
Time

6. To prevent hypoxia we have to identify the fetus likely to be affected
The fetus untroubled by the events of labour.
Troubled but able to fully compensate and is in no immediate danger.
Troubled and utilising key resources in an attempt to compensate or unable to fully compensate.

8. Hypoxia from reduced cord blood flow
Oxygen reduces and CO2 increases (respiratory acidosis develops)
If cord flow is not improved then base excess used up and bicarbonate reduces (metabolic acidosis develops)
Major fetal organ damage

9. Pathophysiology of hypoxia
Negative
Anaerobic metabolism
Glycogenolysis
Lactate
Change in membrane potential due to liberation of potassium
ST segment elevation & high T waves
Metabolic acidosis
DETECT by FBS
DETECT by fetal ECG

10. The first observation 1971

11. ECG waveform analysis Fetal Scalp Electrode
& Maternal skin reference electrode

12. The ECG complex

13. ST-wave forms aerobic myocardial metabolism Normal ST
positive energy balance –
Isoelectric line – T wave
Only Changes in these parameters will be detected – hence the need to start analysis before changes take place

14. Myocardial energy balance
Positive
Available oxygen
Arterial saturation / Haemoglobin
Myocardial blood flow
Negative
Consumed oxygen
(Myocardial work load)
HR / BP / contractility / adrenaline surge

15. ST-wave forms T-wave amplitude hypoxia adrenaline surge
anaerobic metabolism

16. Recording 30 accepted ECG complexes Average ECG T/QRS ratio
biphasic ST

17. Changes in the ST segment & T wave
ST rise – a fetus responding to hypoxia
Biphasic ST – a fetus not fully capable of responding or has not had time to respond

18. ST-wave forms Biphasic ST
Caused by an inability of the myocardium to respond;
Prematurity,
Infections,
Increase in overall demand (mat fever),
Myocardial dystrophy,
Chronic hypoxia,
Initial phase of acute hypoxia.
grade 1
grade 2
grade 3

19. STAN 21

20. Presentation of ST

21. FHR vs STAN – A Swedish RCT
Clinical management – FHR+ST Group
preterminal FHR immediate delivery (regardless of ST)
normal FHR no intervention (regardless of ST)

22. CTG vs. CTG+ST – A Swedish RCT
Clinical management – FHR (CTG)+ST Group
FHR interpretation supported by the ST-log

23. STAN® simplified clinical guidelines
These guidelines are applicable to a term pregnancy of 36 completed gestational weeks or more.
They indicate situations in which intervention is required. This means delivery or alleviation of a cause of fetal distress such as over-stimulation or maternal hypotension. During the second stage of labour with active pushing, immediate delivery is recommended.
If there is an abnormal CTG and a normal ST during the second stage of labour, you can wait 90 minutes before intervention.
The event log requires 20 minutes before automatic ST analysis can begin. At start-up and when there is a decrease in signal quality with discontinuous T/QRS ratios, manual data analysis is required.

24. The outcome of two RCTs

25. The Fetal ECG Project The Derby Experience
Mr Onnig Tamizian -
Clinical Research Fellow, Mr.Ian Symonds - Senior Lecturer, S.Arulkumaran - Professor

26. 7.268+/-0.074
7.195+/-0.077

27. 6.65 mmol/l +/-3.68
4.33 mmol/l +/-3.01

28. 5.88 mmol/l +/-2.39
4.07 mmol/l +/-1.60

30. Cochrane collaboration
Neilson JP. Fetal eleectrocardiogram (ECG) for fetal monitoring during labour. The Cochrane library, Issue 2, Oxford

31. Neilson JP. Fetal eleectrocardiogram (ECG) for fetal monitoring during labour. The Cochrane library, Issue 2, Oxford
The use of ST waveform analysis (7400 women) was associated with fewer babies with severe metabolic acidosis at birth (cord pH <7.05 and BD>12 mmol/L.
RR 0.44, 95% CI
This was achieved with fewer fetal scalp samples during labour (RR 0.86) and fewer operative deliveries (RR 0.89)

32. Neilson JP. Fetal eleectrocardiogram (ECG) for fetal monitoring during labour. The Cochrane library, Issue 2, Oxford
These findings support the use of ST waveform analysis when a decision is made to undertake continuous EFM in labour.
A better approach might be to restrict fetal ST waveform analysis to those fetuses demonstrating disquieting features on CTG (*opinion)

33. Ms L C
30 years old
Primip
PMSH - Nil
Current Pregnancy - uneventful
Admitted T+12 for IOL
Prostin 2mg x 2 on

34. 2200 hrs
CTG after Prostin

35. 06.00 hrs

36. 0600 hours - CTG after SROM - Meconium stained liquor
0630 hours -In view of meconium  Augment with Oxytocin ??

37. 9.00 hrs - persistent decelerations for FBS in view of meconium

38. 1015 hours
FBS pH BE -4.2
Cx - 3cm dilated?

44. 1450 hours
Cx fully dilated
ROT at spines

45. 1520 hours - NVD
Apgar 9 at 1’ & 10 at 5’
Art - pH 7.059, BE 8.17
Ven -pH 7.143, BE 8.71

46. THANK YOU