History of Fetal Monitoring

Em.prof.dr. Fred K. Lotgering Nemo symposium, Eindhoven, 23-01-2018

No conflict of interest to declare

(potentiële) belangenverstrengeling Geen

Voor bijeenkomst mogelijk relevante relaties met bedrijven Geen

• Sponsoring of onderzoeksgeld• Honorarium of andere (financiële)

vergoeding• Aandeelhouder• Andere relatie, namelijk …

• Nvt• Nvt

• Nvt• Nvt

Disclosure

Why history? Facts vs narrative

History

• What?• Nietzsche ‘There are no facts, only interpretations.’

• Why?• Churchill ‘The farther back you can look,

the farther forward you are likely to see.’

‘Fetal monitoring’, a ‘meta’ notion• Basic

• Number• Size• Position

• Physiological activity• Movements• Growth• Heart, circulation• Brain• Bowels• ‘Respiration’• ‘Reactivity’

• Constitution• Anatomically• Genetically

• Biochemical processes• Hormones• Oxygenation, acid/base balance• Other

• ‘Meta’ notions• ‘Fetal monitoring’• ‘Maturity’• ‘Distress’• ‘Outcome’

Fetal monitoring: Applied science & technology

One definition• All obstetric diagnostics (except for what is exclusively maternal)

• Including• Genetic and anatomical constitution• Physiological processes

• As far as practically possible and apparently useful

In this presentation• Focus on electronic fetal monitoring (EFM) of the fetal heart rate,

• As applied physiology• Aiming to prevent damage by hypoxia/ hypoperfusion/ acidosis

• If time permits, discussion on Goals, Reasons, Preconditions

Fetal monitoring, then and now

Literature

Physiological notion• Anaxagoras, ~450 AD

• Food is provided to the fetus through the umbilical cord

• William Harvey, 1651 Exercitationes de generatione animalium(On Animal Generation)

Harvey, On Animal Generation, 1651

• Vs Fabricius (who thinks that blood in the fetus is of maternal origin)• ‘the uterine vessels on the outside, which are large and numerous, and

bring the blood from the mother towards the uterus …’• ‘the uterine caruncles … plainly performed the office of placentae, for

numerous and ample branches of the umbilical vessels penetrated their substance there to imbibe nutritive matther for the growth of the embryo.’

• ‘the embryo by means of its umbilical vessels receives the nourishment that is supplied by the mother’

• ‘the umbilical arteries as they proceed from the bifurcation of the descending aorta’

• ‘… umbilical vein, which ends in the vena cava, … , and passes through the liver, entering the vena portae …’

Fetal heart sounds, auscultation• Le Goust, ~1650 Direct auscultation• Le Jumeau, 1821 ‘Laennec’ stethoscope used for fetus• Nagle, 1830 Detection of twins• Kennedy, 1833 Slow recovery after contraction => poor wellbeing

Moir, 1836 Effect of contractions• Von Hoeff, 1836 Normal range• Bodson, 1843 Very irregular or slow => ‘in articulo mortis’

Kilian, 1849 Indication for forceps delivery• Nauche, 1865 Vaginal stethoscope • Pinard, 1895 Fetal stethoscope• Galabin, 1886 Acceleration 20 bpm => good outcome• Von Winckel, 1893 FHR > 160 or < 100 => poor outcome• Tweedie, 1908 Notion of ‘Fetal distress’

• Schatz, 1872 Tocodynamometer• Einthoven, 1903 String galvanometer, ECG (1924 Nobel Prize)• Cremer, 1906 FECG, abdomino-vaginal• Dressler, 1941 FECG-amplification fetomaternal signal• Williams, 1952 Intrauterine pressure catheter• Hon, 1959 Cardiotocography (FHR + toco vs time)• Hunter, 1960 Scalp-electrode• Hon, 1963 Scalp-electrode (clip)• Favret, 1966 Computer, suppression of maternal signal• Kitahama, 1967 Scalp-electrode (spiral)• Hon, 1972 Disposable spiral electrode

CTG: registration of fetal heart rate + contractions

Cardiotocography

1968 Hon CTG

1872 Schatz tocodynamometer

1972 Hon scalp electrode

CTG-monitoring for ‘fetal distress’• Caldeyro-Barcia, 1966 Classification of decelerations: type 1, 2• Hon, 1968 Classification of decelerations: early, late, variable• Hammacher, 1968 Classification of variability: narrow bandwidth≈hypoxia• Plate, 1969 ‘Please hand me my Pinard horn’ (NTOG nov 2017)

• De Haan, 1971 Sleep, sedatives reduce variability• Beard, 1971 Early deceleration ≈ head compression• Manseau, 1972 Sinusoidal pattern• Renou, 1974 Poor correlation CTG and pH, Apgar-score• Fischer, 1976 Classification system• Visser, 1977 Classification system• Kelso, 1978 No reduction in perinatal mortality• Banta, 1979 Doubling of Cesarean sections• Johnson, 1981 Sinusoidal pattern ≈ anemia• Van den Berg, 1987 PPV EFM for umb pH <7,2 = 29%

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CTG-monitoring for ‘fetal distress’• MacDonald, 1985 Dublin trial, RCT 12964 pt, no effect on poor outcome,

(Chalmers) CS 2,4 vs 2.2%, forceps 8,2 vs 6,3%

• Freeman, 1990 ‘A disappointing story’

• Alfirevic, 2017 Cochrane, EFM by CTG during labor: no differences in infant mortality or ‘poor outcome’except for ↓ neonatal seizures, yet associated with↑ caesarean sections and instrumental vaginal births

Foetaal-ECG als techniek• Cremer, 1906 FECG• Tarnover, 1942 AV node tachycardia• Garvin, 1952 Supraventriculaire tachycardie• Southern, 1957 P-wave↑, PR segment↑, ST segment = /↓ by distress• Smith, 1960 Congenital heartblock• Cox, 1963 RR-interval electronically useful for FHR• Hon, 1963 Waveform changes occur only shortly before death• Rosén, 1889 STAN (ST-segment analysis)

FECG-monitoring for ‘fetal distress’• Westgate,1993 STAN, no effect on ‘poor outcome’,

46% ↓ in assisted vaginal deliveries for ‘fetal distress’ Westgate, 2001 STAN poor indicator of hypoxia

with cord compression in sheep• Belfort, 2015 STAN RCT 11,108 pt no effect

• Neilson, 2015 Cochrane, STAN no effect, except for ↓ FBS and assisted vaginal deliveries

Antepartum CTG, as monitoring technique• Hofbauer, 1908 FPCG, phonocardiography• Gunn, 1953 Analysis of FPCG• Donald, 1958 Pulsed ultrasound in Ob• Hammacher, 1966 FPCG apparatus, antepartum monitoring• Bishop, 1966 Doptone• Maeda, 1969 Doppler CTG• Kubli, 1969 Stress testing• Sanchez-Ramos, 1971 No mortality < 1 wk after negative test• Ray, 1972 Oxytocin Challenge Test (OCT)• Lee, 1976 NST, NonStressTest, instead of OCT• Manning, 1980 Nonreactive NST ≈ distress in 31%• Lotgering, 1982 Poor inter- and intra-observer variation• Smith, 1987 Reactieve NST ≈ perinatal mortality 2-5‰• Dawes,Redman, 1991 System 8000, computerized antenatal CTG analysis• Grivell, 2015 Cochrane, no effect on ‘poor outcome’

Electronic fetal monitoring • CTG during delivery• CTG prior to delivery ‘A disappointing story’ (scientifically, not commercially)

• STAN

Why is EFM disappointing?• The promise

• To prevent or reduce fetal damage and/or handicaps

• The pitfall• Present-day EBM technology has poor operator characteristics

(diagnosis and treatment) • yet imposes itself by lack of a better method

• One possible explanation why• Perhaps the preconception that electrical/ mechanical activity of the

fetal heart is a truly sensitive and accurate indicator of hypoxemia/ acidosis is false, or at least an oversimplification

Fetus/neonate more hypoxia-resistent than adult• Harvey, 1651 Fetus survives some time in dead mother (human, deer, rabbit)• Boyle, 1670 Neonate survives asphyxia longer than adult (cat)• Le Gallois, 1812 Neonate survives asfyxia longer than adult (rabbit)• Pflüger, 1877 Fetus can survive anoxia for some time (human)• Zuntz, 1884 With maternal asphyxia, the fetus and neonate live longer than

the mother (rabbit)• Glass, 1944 Survival time diminishes with age, before and after birth (rabbit)

• Bennet, 2017 Preterm fetus has great defences against hypo-oxygenation

• Clinically Evident that immature neonate has long ‘time to last gap’

Harvey on hypoxia-resistance in utero

• ‘In the Caesarean section, also, it is quite clear that the life of the embryo does not immediately depend upon the mother, and that the spirits do not proceed from her; for I have often seen the foetus extracted alive from the uterus when the mother has been dead some hours.’

• ‘I have also known the rabbit and hare survive when extracted from the uterus of the dead mother.’

• ‘Nay, in the Caesarean section, when the embryo is still enveloped in the chorion, I have often found the umbilical arteries pulsating, and the foetus lively, even when the mother was dead and her limbs stiffened’

• ‘The foetus has a proper life of its own’

https://ia902608.us.archive.org/26/items/worksofwilliamha00harviala/worksofwilliamha00harviala_bw.pdf

R.Boyle. Phil Trans R Soc 1670; 5: 2011-31

Boyle on resistance to hypoxia in neonate

Neonate more hypoxia-resistent than adult

Le Gallois. Expériences sur le principe de la vie. Paris, Hautel 1812

Survival in neonatal rabbits

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H.G.Glass et al. Am J Physiol 1944; 140: 609-615

Preterm fetus more resistent than at term• “The preterm fetus is a veritable

warrior when it comes to defending itself from challenges to its oxygenation”, through • Robust, homeostatically titrated, co-

ordinated cardiovascular, behavioural and metabolic defence to hypoxic insults.

• Added armoury of greater anaerobic reserves combined with a lower metabolic demand.

• Much better phase two, resulting in a slowing of the inevitable descent into decompensation and death.

L.Bennett J Physiol 2017; 595: 1865

Combi (hypoxemia + hypoperfusion) is damaging• Monitoring ideally through true indicators of circulation:

• Cardiac output (blood volume flow, not FHR pattern)• Blood pressure • Systemic vascular resistance

• In addition to indicators of hypoxemia• VO2• [O2]• PO2

• And/or metabolic acidiosis• pH• PCO2• BE

Gunn, Bennett. Fetal hypoxia insults and patterns of brain injury: Insights from animal models. Clin Perinatol. 2009; 36: 579–593.

Philosophical footnotes

• Man (MD, patient) aims for optimal new individual (child)• Individual interest is central, yet sociocultural factors are also important

• Doctor has right to intervene for presumed benefit of the fetus, by maternal intervention (e.g. Cesarean section)• And/or to terminate the life of the infant for presumed lack of quality of

life (with or without additional legal conditions (NL < 24 wk, ≥ 24 wk))• We accept explicit and implicit risks associated with EFM, e.g.

• Diagnostics as goal in itself (without clear-cut consequences or benefit)• Over- and under-treatment (e.g. CS for presumed fetal hypoxemia)• Irrational components in clinical decisions (e.g. authority-based)

Scientific revolutions

not linear!

Progress in science according to Popper

• Science progresses when we realize that a particular way of thinking about reality is false.

• Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.

Concluding quotations• Confucius

• To know what you know and what you don’t know, that is true knowledge.

• Nietzsche • Many are stubborn in pursuit of the path they have chosen,

few in pursuit of the goal.