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Fetal Monitoring. Scott A Sullivan MD MSCR Maternal-Fetal Medicine MUSC October 12, 2010. Disclosures. I have no disclosures or conflicts to report. Disclosures – I am from MUSC!. Learning Objectives. Discuss NICHD Consensus Recommendations Review fetal physiology and EFM patterns
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Fetal Monitoring Scott A Sullivan MD MSCR Maternal-Fetal Medicine MUSC October 12, 2010
Disclosures • I have no disclosures or conflicts to report
Learning Objectives • Discuss NICHD Consensus Recommendations • Review fetal physiology and EFM patterns • Alternate technology – what works, what doesn’t and what is coming
A bit of history… • Marzac – 1620 First description of fetal heart tones • Killian – 1640 Theory that heart tones = fetal health • Kergaradec – 1818 Technique, viability • Kennedy – 1833 Intra-partum monitoring • Von Winkel – 1893 “Fetal Distress” definitions • DeLee / Hillis – 1922 Fetoscope • Matthews – 1940 Amplified fetoscope
Edward H Hon, MD 1915 – 2009 Father of modern EFM 1958
1968 – Commercially available 1972 – First scalp electrode 1970’s – Coins deceleration terms 1975 – 20 % of labors used EFM
EFM – Antepartum Testing Reactivity translates to a fetal death rate of < 5 /1000 Non-reactivity = fetal mortality rate of 40/1000 False positive rate 50-97(!) % Unless ominous, requires a confirmatory test
So How Have We Done? • 1975 – 2010 • Decreased fetal death incidence • Cesarean section rate increased 110 % • Cerebral palsy incidence unchanged • Lawsuit rate / live-birth rate increased 340 %
EFM vs. IA • Cochrane Review – 2001 • 9 RCTs • 18,561 patients • No difference in Apgars, NICU, fetal death and cerebral palsy • Reduction in seizures (RR 0.51 0.32-0.82) • Increases in C/S and OVD
Vintzileos – EFM vs IA • 1995 • Decrease in perinatal mortality (1/1000) • 1996 • Sensitivity – 97 % vs. 34 % • Specificity – 84 % vs. 91 % • PPV – 34 % vs. 22% • NPV – 99.5 % vs. 95 %
What’s the Problem? • Subjective interpretation • Technological limitations • Lack of interventional guidelines • Confusing terminology
Terminology • Gabbe vs. Williams • “Short-Term”, “Beat to Beat” • Lack of inter-rater reliability • 1997 Consensus
Inter-rater reliability • 4 OBs – 22 % agreement (Nielson) • 2 months later, re-reviewed • 25 % changed their own interpretation • 5 Obs – 29 % agreement (Beaulieu)
NICHD Conference • 2008 • Series of meetings • Jointly published in OBG, Pediatrics, Neonatology OBG 112(3);Sept 2008 661-666
Category I • Must include ALL : Baseline 110-160 Moderate variability No late decelerations Early decelerations +/- Accelerations +/-
Category I • “Normal” • “Highly Predictive of a normal fetal pH” • No Action Required
Category III • Absent variability, plus either Recurrent late decelerations Recurrent variable decelerations Bradycardia • Sinusoidal pattern
Category III • “Abnormal” • “Predictive of abnormal acid-base status” • Requires prompt intervention or delivery
MANAGEMENT OF Cat III • Discontinued oxytocin • Begin oxygen 5-6 L/min • Correct maternal hypotension • Trendelenberg position • Increase IV fluids • Vasopressor (ephedrine 15 mg IV) • Assess maternal oxygenation and acid/base status • Terbutaline 0.25 mg SQ for in-utero resuscitation
Environment Oxygen transfer can be disrupted at any ofthese points and can manifest as FHRdeceleration (variable, late, prolonged) The degree of oxygen disruption is theimportant factor, not the point in thepathway at which oxygen transfer isdisrupted Lungs Heart Vasculature Uterus Placenta Cord Fetus Hypoxemia Hypoxia Metabolic acidosis acidemia Hypotension Oxygen transfer Fetal response Potential Injury
DECREASED UTEROPLACENTAL OXYGEN TRANSFER TO THE FETUS Chemoreceptor Stimulus Alpha Adrenergic Response WithoutAcidemia WithAcidemia Fetal Hypertension Baroreceptor Stimulus Parasympathetic Response MyocardialDepression Deceleration
Category II • “Everything that not categorized as either Category I or III” • Examples : Tachycardia, bradycardia with normal variability • Absent variability, marked variability • Lates + variability, unusual variables
Category II • Category II FHR tracings are considered “indeterminate” • Not predictive of abnormal fetal acid-base status but inadequate evidence to classify as Category I or III • Requires evaluation and in-utero treatment if appropriate • Requires continued surveillance and re-evaluation in context of clinical circumstances
Variability • Moderate FHR variability is HIGHLY predictive of the absence of metabolic acidemia at the time it is observed Parer JT J Maternal Fetal Neonatal Med 2006; 19:289-94 Low JA Obstet Gynecol 1999; 93:285-91Williams KP Am J Obstet Gynecol 2003; 188:820-3Elimian A Obstet Gynecol 1997; 89:373-6
MINIMAL OR ABSENT FHR VARIABILITY • CNS depressants: Narcotics, Barbiturates, Benzodiazapines, Sedatives, Alcohol • Parasympatholytics: Phenothiazines, Atropine • General anesthetics • Magnesium sulfate • Fetal tachycardia due to maternal fever or fetal infection • Preexisting neurological injury • Fetal acidosis/acidemia
NICHD 2008 - Pros • Simple • Better than 1998 • More widely adopted • ACOG buy-in
NICHD 2008 - Cons • No evidence the system is actually better • Lack of actionable recommendations • Category II ?? • Does not fix problems of EFM
A word about contractions • Normal ≤ 5 contractions / 10 m • Tachysystole ≥ 5 contractions / 10 m • No hyperstimulation!
How About < 32 weeks? • No clear recommendations • < 28 weeks, 50 % will be non-reactive • 28-34 weeks, 15 % • “10 x 10”?
VAS? • Artificial larynx used to stimulate the fetus • Shortens time to reactivity 9.9 minutes • 88 dB in the uterus • Appears to be safe • Reactive NST is just as reliable ?
What’s New? It’s clear we need something better Fetal Pulse-Oximetry STAN
Fetal Pulse Oximetry • Same technology • Oxygen saturation • Mechanical problems
FPO – Cochrane Review • 2007 • 5 trials • 7424 subjects • Overall no decrease in cesarean rate, seizures • Fetal scalp sampling? East CE, Cochrane Database 2007
STAN • ST Waveform Analysis • Automated analysis of ST segments • Uses EFM + ST • FDA approved - 2005
2001 Lancet - STAN • Sweden RCT • 4966 subjects • STAN vs EFM alone • Decrease in acidosis [RR 0.47 0.25-0.81] • Decrease in OVD [RR 0.83 0.69-0.99] Amer-Wehlin, Lancet 2001
2006 BJOG - STAN • RCT • 1493 subjects • Similar design • No difference in acidosis • No difference in cesarean section or OVD Ojala K, BJOG 2006
STAN – Cochrane Review • 2006 • 4 trials, 9829 subjects • No difference in C/S, OVD • Decreased acidosis [RR 0.64 0.41 – 0.99] • Decreased HIE [RR 0.33 0.11-0.91] • Insufficient evidence to recommend Neilson, JP Cochrane Database 2006
Newer things…. • Doppler? • WAS – 2009 • ANBLIR – 2010 (fuzzy logic, ANN) • NIR photopleythysmography
What does ACOG Say? • Practice Bulletin 106 • Endorses terminology • High risk women need continuous EFM, for others it is optional • No to FPO