ST analysis of the fetal electrocardiogram - Comments on recent experimental data.

In their paper, Andriessen at al present a validation of fetal ECG analysis and the clinical STAN device in midgestation fetal lambs exposed to 25 minutes of umbilical cord occlusion. The study presents results that contrast remarkably from previously published experimental data which raises a number of questions and comments. The most striking finding of Andriessen et al is the recording of an extremely high number of alarms from the STAN equipment during control conditions when no alarms at all are expected.

Waveform analysis of the fetal ECG in labor in patients with intrahepatic cholestasis of pregnancy.

Aim: Intrahepatic cholestasis of pregnancy (ICP) is reported to be associated with an increased risk of sudden fetal death. The possible mechanism is thought to be cardiac arrhythmia. Prolonged QT interval of the electrocardiogram (ECG) is associated with arrhytmogenic events.

Identifying newborns with umbilical cord blood metabolic acidosis by intrapartum cardiotography combined with fetal ECG ST analysis (STAN): comparison of the new and old FIGO systems to classify cardiotocograms.

The intrapartum cardiotocography (CTG) classification system by FIGO in 2015 (FIGO2015) was introduced to simplify CTG interpretation, but it is not harmonized with the fetal ECG ST analysis (STAN) algorithm from 2007 (STAN2007), which is based on the FIGO CTG system from 1987. The study aimed to determine time courses and sensitivity between the systems in classifying CTG + ST events to indicate metabolic acidosis at birth. Forty-four cases with umbilical cord artery metabolic acidosis were retrieved from a European multicenter database.

FHR patterns that become significant in connection with ST waveform changes and metabolic acidosis at birth.

Recent developments have produced new CTG classification systems and the question is to what extent these may affect the model of FHR + ST interpretation? The two new systems (FIGO2015 and SSOG2017) classify FHR + ST events differently from the current CTG classification system used in the STAN interpretation algorithm (STAN2007). Identify the predominant FHR patterns in connection with ST events in cases of cord artery metabolic acidosis missed by the different CTG classification systems. Indicate to what extent STAN clinical guidelines could be modified enhancing the sensitivity.

Do spectral bands of fetal heart rate variability associate with concomitant fetal scalp pH?

Background: Objective information on specific fetal heart rate (FHR) parameters would be advantageous when assessing fetal responses to hypoxia. Small, visually undetectable changes in FHR variability can be quantified by power spectral analysis of FHR variability.

Aims: To investigate the effect of intrapartum hypoxia and acidemia on spectral powers of FHR variability.

Association between umbilical cord artery pCO₂ and the Apgar score; elevated levels of pCO₂ may be beneficial for neonatal vitality after moderate acidemia.

Objective: To determine the association between 5-min Apgar score and umbilical cord artery carbon dioxide tension (pCO₂).

Design: Observational study.

Setting: European hospital labor wards.

Developmental outcome at 6.5 years after acidosis in term newborns: a population-based study.

Objectives: Infants who develop encephalopathy after perinatal asphyxia have an increased risk of death and adverse neurologic outcome. Conflicting results exist concerning outcome in healthy infants with metabolic acidosis at birth. The aim of the current study was to evaluate whether metabolic acidosis at birth in term infants who appear healthy is associated with long-term developmental abnormalities.

Swedish randomized controlled trial of cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram revisited: analysis of data according to standard versus modified intention-to-treat principle.

Objective: To undertake a renewed analysis of data from the previously published Swedish randomized controlled trial on intrapartum fetal monitoring with cardiotocography (CTG-only) vs. CTG plus ST analysis of fetal electrocardiogram (CTG+ST), using current standards of intention-to-treat (ITT) analysis and to compare the results with those of the modified ITT (mITT) and per protocol analyses.

Methods: Renewed extraction of data from the original database including all cases randomized according to primary case allocation (n=5 049).

Allopurinol reduces oxidative stress in the ovine fetal cardiovascular system after repeated episodes of ischemia-reperfusion.

In complicated labor, neonatal outcome may depend not only on the extent of fetal asphyxia and acidosis but also on the effects on the fetal cardiovascular system of reactive oxygen species (ROS) generated during the ischemia-reperfusion (I/R) associated with repeated compressions of the umbilical cord. This study tested the hypothesis that maternal treatment with clinical doses of the antioxidant allopurinol in the setting of fetal asphyxia would reduce oxidative stress in the fetal cardiovascular system. The hypothesis was tested in chronically instrumented fetal sheep in late gestation by investigating the effects of maternal treatment with therapeutic doses of allopurinol or vehicle on the fetal cardiovascular system during and after episodes of I/R.

A comparative study of fetal heart rate variability analysis techniques.

This study examines a novel methodology for continuous fetal heart rate variability (FHRV) assessment in a non-stationary intrapartum fetal heart rate (FHR). The specific aim was to investigate simple statistics, dimension estimates and entropy estimates as methods to discriminate situations of low FHRV related to non-reassuring fetal status or as a consequence of sedatives given to the mother. Using a t-test it is found that the dimension of the zero set and sample entropy reveal a difference in mean distribution of significance >99%.

Fetal scalp pH and ST analysis of the fetal ECG as an adjunct to cardiotocography to predict fetal acidosis in labor--a multi-center, case controlled study.

Objective: To assess the relationship between scalp pH (FBS) and ST analysis in situations of acidosis with special emphasis on the timing of cardiotocography (CTG), FBS and ST changes during labor.

Study Design: From a European Union multicenter study on clinical implementation of the STAN methodology, 911 cases were identified where a scalp-pH had been obtained. In 53 cases, marked cord artery acidosis was found (cord artery pH<7.

Marked fetal acidosis and specific changes in power spectrum analysis of fetal heart rate variability recorded during the last hour of labour.

Objective: To assess whether intrapartum acidosis affects specific components of fetal heart rate variability.

Design: Prospective clinical study.

Setting: Twelve Nordic delivery units.

Fetal electrocardiogram waveform analysis in labour.

Purpose Of Review: ST-waveform analysis of the fetal electrocardiogram (ECG) has emerged from experimental and observational studies to clinical use based on the outcome of two large randomized controlled trials and a European Union-supported project on the structured dissemination of knowledge and experience by establishing regional centres of excellence. The review focuses on the outcome from the host of studies and those recently published.

Recent Findings: The database is dominated by a Swedish randomized controlled trial demonstrating not only improved outcome with regard to cord-artery metabolic acidosis and fewer operative interventions for non-reassuring fetal state but, most importantly, the marked and significant reduction in the risk of neonates showing signs of moderate or severe neonatal encephalopathy.

Fetal scalp pH and ST analysis of the fetal ECG as an adjunct to CTG. A multi-center, observational study.

Objective: To evaluate the relationships between scalp-pH and CTG plus ST waveform analysis of the fetal ECG (STAN) clinical guidelines as indicators of intrapartum hypoxia in term fetuses born with cord artery acidemia.

Study Design: Data from 6999 term deliveries monitored by the STAN (R) S 21 as part of an EU multi-center study on clinical implementation of the STAN methodology for intrapartum fetal surveillance were analyzed. We identified 911 cases where a scalp-pH was obtained, including 53 cases with cord artery acidemia (pH < 7.

The effects of intrapartum hypoxia on the fetal QT interval.

Background: The morphology of the fetal ECG complex provides information on the fetal condition during labour, such as the ST segment and T-wave configuration. We hypothesised that the intrapartum fetal QT interval may provide additional information on the condition of the fetus, as it is known that the QT interval reacts to situations of stress and exercise.

Design: Retrospective study.

Fetal ECG waveform analysis.

Fetal ECG waveform analysis as an adjunct to electronic fetal monitoring (EFM) has developed over the last 3 decades. From a multitude of potential parameters, ST waveform analysis has been documented to provide the information required to shift EFM from a screening device to a diagnostic tool that meets the standards of evidence-based medicine. This chapter details the experimental and clinical evolution of the STAN methodology for intrapartum fetal surveillance.

Fetal electrocardiography in labor and neonatal outcome: data from the Swedish randomized controlled trial on intrapartum fetal monitoring.

Objective: Cardiotocography plus automatic ST analysis of the fetal electrocardiography has been shown recently to reduce both the operative delivery rate for fetal distress and the cord artery metabolic acidosis rate. The purpose of this study was to analyze findings that were related to cases with a complicated/adverse neonatal outcome in the Swedish randomized controlled trial.

Study Design: Of the 4966 term fetuses that were included in the trial, all 351 newborn infants who required special neonatal care were identified.