ST Segment Analysis (STAN) for Intrapartum Electronic Fetal Monitoring

Presented By: Chukwuma I. Onyeije, M.D. Atlanta Perinatal Associates Clinical Associate Professor, Morehouse School of Medicine

Specific FHR abnormalities are related to cerebral palsy and neurologic injury in the fetus

The 1970s CLINICAL OBSTETRICS AND GYNECOLOGY Volume 54, Number 1, 56–65 r 2011, Lippincott Williams & Wilkins

Intrapartum EFM associated with decreased perinatal mortality due to fetal hypoxia but also with higher rates of surgical intervention for suspected fetal distress. Vintzeleos et al, Obstet Gynecol. 1993 Jun;81(6):899-907.

Compared to Auscultation, EFM results in higher operative delivery rates without significant lowering of perinatal mortality.

Conclusion: Auscultation…. The winner!

Scalp pH
Pulse Oximetry

Scalp pH largely abandoned in the United States 2 decades ago.
Fetal pulse oximetry did NOT reduce cesarean delivery rates for ‘nonreassuring’’ FHR patterns in NICHD trial.

The fetal ST interval changes in the fetus suffering from oxygen deficiency.
ST Analysis (STAN) consists of highlighting theses changes.

For a fetus, the birth is the treadmill.

STAN begins with conventional EFM (FHR + UCs) and adds automated ST Analysis
Comprehensive and mandatory education prior to introduction of STAN

Showed that hypoxia was associated with a significant elevation of the T-wave in the fECG.
Am J Obstet Gynecol. 1984;149:190–195.

Increased myocardial glycogen breakdown
Liberation of potassium
Increased local catecholamines

The increase in T-wave height relative to the amplitude of the QRS complex was identified when the fetus transitions from aerobic to anaerobic metabolism.

The T:QRS ratio measures of myocardial metabolic status
Other changes in the ST-segment identified fetuses with chronic oxygen deprivation were subjected to acute hypoxic stress.

Baseline T :QRS ratio
Appearance of ST segment waveforms

Hypoxic fetuses
Fetuses with myocardial dysfunction
Chronically hypoxic fetuses with acute insults

BEFORE using STAN
>36+0 gestational weeks
Ruptured membranes
No contraindication for scalp electrode or STAN
First stage, no active or involuntary pushing

At onset of STAN
Classify the FHR.
Check for FHR reactivity
Confirm nondeteriorating fetal state
Check for normal ECGwaveform
Confirm sufficient signal quality
Confirm baseline T:QRS ratio

Any contraindication to invasive monitoring
active maternal herpes
HIV
Hepatitis

STAN
determines baseline T:QRS ratio over 20 T :QRS ratios and then tracks for changes over time.

T:QRS Ratio   EVENT LOG  AVERAGE T:QRS  ST ALRETS

Episodic rise in T:QRS ratio
(greater than 0.10 for less than 10 min);
Baseline rise in T :QRS ratio
(greater than 0.05 for more than 10 min); and
Recurrent biphasic ST segments

FHR CLASSIFICATION BASELINE FHR VARIABILITY DECELERTIONS GR EEN 110 - 160 MODERATE (+)ACCELERATIONS EARLY VARIABLE (LESS THAN 60 x 60) YELLOW BRADY <110 TACHY > 160 > 150 WITH MINIMAL VARIABILITY MINIMAL FOR > 40 MIN MARKED FOR > 40 MIN VARIABLE GREATER THAN 60 x 60 RECURRENT LATE PROLONGED RED SINUSOIDAL OR ABSENT VARIABILITY REGARDLESS OF FHR PATTERN

STAN’s FHR Clinical Management Protocol FHR CLASSIFICATION NO ST EVENTS ST EVENTS PRESENT GR EEN EXPECTANT MANAGEMENT CONTINUED OBSERVATION YELLOW EXPECTANT MANAGEMENT DIRECT PHYSICIAN ASSESSMENT OF FETAL STATE IF > 60 MINUTES DIRECT PHYSICIAN ASSESSMENT INTRAUTERINE RESUSCITATION EXPEDITED DELIVERY IF NO IMPROVEMENT RED EXPEDITIOUS DELIVERY / RESUSCITATION (?)

Main outcome of interest was a reduction in cord artery metabolic acidosis (pH <7.05 and base deficit >12 mmol/L) with the addition of STAN data.
U.K. – Am J Obstet Gynecol. 1993;169:1151–1160. Sweden - Lancet. 2001;358:534–538.

UNITED KINGDOM: 1993 SWEDEN: 2001

Significant reduction in fetal metabolic acidosis AND reduction in operative delivery.
Follow-up studies of the neonates showed a significant reduction in neonatal encephalopathy

Standard EFM is very good at detecting the very healthy and very sick fetus.
STAN allows us to grade fetuses between the extremes

STAN combined with EFM provides more accurate information about the fetus during labor than EFM alone.
STAN is automatic, continuous and has been proven to be effective in large randomized trials.

Information from STAN provides precise information about the fetal state during labor to detect fetuses at risk and avoid unnecessary interventions.

CLINICAL OBSTETRICS AND GYNECOLOGY Vol.54, Number 1, 56–65. 2011,
Am J Obstet Gynecol. 1993;169:1151–1160.
Lancet. 2001;358:534–538.
Am J Obstet Gynecol.1984;149:190–195.
Obstet Gynecol. 1993 Jun;81(6):899-907
http://www.neoventa.com/INT/Articles/Products/Goldtrace_INT.html

ST Segment Analysis (STAN) for Intrapartum Electronic Fetal Monitoring

by Chukwuma Onyeije on Sep 08, 2011

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ST Segment Analysis (STAN) for Intrapartum Electronic Fetal Monitoring — Presentation Transcript