Presentation on theme: "Introducing Fetal ECG waveform analysis for Intrapartum Care S Arulkumaran Professor & Head – Obstetrics & Gynaecology St.George’s Hospital Medical School."— Presentation transcript:
Introducing Fetal ECG waveform analysis for Intrapartum Care S Arulkumaran Professor & Head – Obstetrics & Gynaecology St.George’s Hospital Medical School University of London
Fetal Hypoxaemia > Hypoxia > Asphyxia How to prevent fetal hypoxia? Diagnose hypoxia Institute corrective measures Deliver
Fetal response to hypoxemia Time Oxygen saturation Days and weeks HoursMinutes Hypoxemia Hypoxia Asphyxia more effective uptake of oxygen Reduced activity Reduced activity decrease in growth rate maintained energy balance
The fetal response to hypoxia Time Oxygen saturation Days and weeks Hours Minutes Hypoxemia Hypoxia Asphyxia surge of stress hormones redistribution of blood flow anaerobic metabolism in the peripheral tissues maintained energy balance
Fetal response to asphyxia Time Oxygen saturation Days and weeks Hours Minutes Hypoxemia Hypoxia Asphyxia Alarm reaction anaerobic metabolism in peripheral tissues brain and heart organ failure
To prevent hypoxia we have to identify the fetus likely to be affected The fetus untroubled by the events of labour.The fetus untroubled by the events of labour. Troubled but able to fully compensate and is in no immediate danger.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.Troubled and utilising key resources in an attempt to compensate or unable to fully compensate.
Hypoxia from reduced cord blood flow Oxygen reduces and CO 2 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
Lactate Anaerobic metabolism Glycogenolysis Change in membrane potential due to liberation of potassium ST segment elevation & high T waves Negative Metabolic acidosis Pathophysiology of hypoxia DETECT by FBS DETECT by fetal ECG
ST-wave forms aerobic myocardial metabolism 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 Normal ST
Myocardial energy balance Positive Negative Available oxygen Arterial saturation / Haemoglobin Myocardial blood flow Consumed oxygen (Myocardial work load) HR / BP / contractility / adrenaline surge
ST-wave forms hypoxia adrenaline surge anaerobic metabolism T-wave amplitude
Recording Recording T/QRS ratio biphasic ST Average ECG 30 accepted ECG complexes
Changes in the ST segment & T wave 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
ST-wave forms grade 1 grade 2 grade 3 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.
Presentation of ST Presentation of ST
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)
CTG vs. CTG+ST – A Swedish RCT Clinical management – FHR (CTG)+ST Group FHR interpretation supported by the ST-log
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.
The outcome of two RCTs
The Fetal ECG Project The Derby Experience Mr Onnig Tamizian - Clinical Research Fellow, Mr.Ian Symonds - Senior Lecturer, S.Arulkumaran - Professor
6.65 mmol/l +/ mmol/l +/-3.01
5.88 mmol/l +/ mmol/l +/-1.60
Cochrane collaboration 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 12 mmol/L.The use of ST waveform analysis (7400 women) was associated with fewer babies with severe metabolic acidosis at birth (cord pH 12 mmol/L. RR 0.44, 95% CI 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)
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.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) A better approach might be to restrict fetal ST waveform analysis to those fetuses demonstrating disquieting features on CTG (*opinion)
Ms L CMs L C 30 years old30 years old PrimipPrimip PMSH - NilPMSH - Nil Current Pregnancy - uneventfulCurrent Pregnancy - uneventful Admitted T+12 for IOLAdmitted T+12 for IOL Prostin 2mg x 2 on Prostin 2mg x 2 on
2200 hrs CTG after Prostin
0600 hours - CTG after SROM - Meconium stained liquor 0630 hours -In view of meconium Augment with Oxytocin ??
9.00 hrs - persistent decelerations for FBS in view of meconium
1015 hours FBS pH BE -4.2 Cx - 3cm dilated?
1450 hours Cx fully dilated ROT at spines
1520 hours - NVD Apgar 9 at 1’ & 10 at 5’ Art - pH 7.059, BE 8.17 Ven -pH 7.143, BE 8.71