st segment analysis (stan) for intrapartum electronic fetal monitoring
DESCRIPTION
ST Segment Analysis (STAN) for Intrapartum Electronic Fetal MonitoringTRANSCRIPT
Presented By:Chukwuma I. Onyeije, M.D.Atlanta Perinatal AssociatesClinical 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 GYNECOLOGYVolume 54, Number 1, 56–65r 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
GREEN110 - 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
GREEN EXPECTANT MANAGEMENTCONTINUED 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