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PubMed · 7674103

Computerized evaluation of fetal heart-rate patterns.

G Dawes·Y J Meir·G P Mandruzzato
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Abstract

Antepartum Cardiotocography (CTG) is one of the few techniques available today to assess fetal conditions in high risk pregnancies. Visual interpretation of CTG traces has been shown to be unreliable. In order to eliminate observer variability and to increase the accuracy of CTG, numerical on-line analysis of fetal heart rate (FHR) patterns was introduced. The experience with computerized systems has shown that the best indicator of fetal conditions is variation, long- or short-term. Mean range (Long-term variation) values of less than 20 msec are associated with an increased rate of fetal acidaemia and perinatal mortality. The availability of numerical measurements enables the detection of small changes in FHR occurring in time, so when initial deterioration signs arise, the single fetus can be followed up longitudinally. Moreover, a more accurate correlation with other biophysical and biochemical parameters of the fetus can be done, as well as with perinatal outcome. In conclusion, computerized CTG improves accuracy and allows to distinguish fetuses that are truly jeopardized because of hypoxemia, from those who are not.

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CardiotocographyComputersFemaleFetal MovementHeart Rate, FetalHumansPregnancyJournal ArticleReview

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G Dawes, Y J Meir, G P Mandruzzato. 1994. Computerized evaluation of fetal heart-rate patterns.. https://doi.org/10.1515/jpme.1994.22.6.491

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PubMed2006

Twenty-four-hour CTG monitoring: comparison of normal pregnancies of 25-30 weeks of gestation versus 36-42 weeks of gestation.

OBJECTIVE: Routinely antepartal cardiotocogram (CTG) is recorded for 30 min in order to obtain normal resting phases (<30 min) or a decrease of irregulatory due to hypoxia (>30 min) or to differentiate these from each other. In case of early onset of hypoxia first pathological findings might only be seen by chance in incidentally recorded CTG. The goal of this study was, if a continuous 24-h CTG allows an earlier detection of beginning hypoxia in case of normal pregnancies of 36-42 weeks compared to pregnancies of 25-30 weeks of gestation, and if there are any differences between both groups concerning the qualitative and quantitative description or the detection of a circadian rhythm. METHODS: 21 patients in each group had 24-h CTGs by means of telemetry (Hewlett-Packard type 78101A, 80110A). In both study groups, fetal heart-rate tracing included a full qualitative and quantitative description. Comparison of the results of both groups was done to look for early signs of pathological findings concerning reduced fetal well-being and a potential day and night rhythm. RESULTS: In comparison to 36-42 weeks of pregnancies 25-30 weeks had significantly more physiological undulatory oscillation and less narrowed undulatory oscillation (P < 0.001), as well as less resting phases (P < 0.001). Baseline tachycardia and bradycardia showed significantly increasing quantity (P < 0.001). CONCLUSION: Twenty-four-hour CTG is a good screening method to detect early onset of hypoxia in case of second and third trimester pregnancies and a big help to detect a fetus at risk earlier. In future computerized CTG-systems should be proved in this connection and should be compared with our study.

Cardiotocography↗
PubMed2006

Fetal electrocardiogram (ECG) for fetal monitoring during labour.

BACKGROUND: Hypoxaemia during labour can alter the shape of the fetal electrocardiogram (ECG) waveform, notably the relation of the PR to RR intervals, and elevation or depression of the ST segment. Technical systems have therefore been developed to monitor the fetal ECG during labour as an adjunct to continuous electronic fetal heart rate monitoring with the aim of improving fetal outcome and minimising unnecessary obstetric interference. OBJECTIVES: To compare the effects of analysis of fetal ECG waveforms during labour with alternative methods of fetal monitoring. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2006). SELECTION CRITERIA: Randomised trials comparing fetal ECG waveform analysis with alternative methods of fetal monitoring during labour. DATA COLLECTION AND ANALYSIS: Trial quality assessment and data extraction were performed by the review author, without blinding. MAIN RESULTS: Four trials including a total of 9829 women were included. In comparison to continuous electronic fetal heart rate monitoring alone, the use of adjunctive ST waveform analysis (three trials, 8872 women) was associated with fewer babies with severe metabolic acidosis at birth (cord pH less than 7.05 and base deficit greater than 12 mmol/L) (relative risk (RR) 0.64, 95% confidence interval (CI) 0.41 to 1.00, data from 8108 babies), fewer babies with neonatal encephalopathy (three trials, RR 0.33, 95% CI 0.11 to 0.95) although the absolute number of babies with encephalopathy was low (n = 17), fewer fetal scalp samples during labour (three trials, RR 0.76, 95% CI 0.67 to 0.86) and fewer operative vaginal deliveries (three trials, RR 0.87, 95% CI 0.78 to 0.96). There was no statistically significant difference in caesarean section (three trials, RR 0.97, 95% CI 0.84 to 1.11), Apgar score less than seven at five minutes (three trials, RR 0.80, 95% CI 0.56 to 1.14), or admissions to special care unit (three trials, RR 0.90, 95% CI 0.75 to 1.08). Apart from a trend towards fewer operative deliveries (one trial, RR 0.87, 95% CI 0.76 to 1.01), there was little evidence that monitoring by PR interval analysis conveyed any benefit. AUTHORS' CONCLUSIONS: These findings provide some support for the use of fetal ST waveform analysis when a decision has been made to undertake continuous electronic fetal heart rate monitoring during labour. However, the advantages need to be considered along with the disadvantages of needing to use an internal scalp electrode, after membrane rupture, for ECG waveform recordings.

Cardiotocography↗
PubMed2006

Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour.

BACKGROUND: Cardiotocography (sometimes known as electronic fetal monitoring), records changes in the fetal heart rate and their temporal relationship to uterine contractions. The aim is to identify babies who may be short of oxygen (hypoxic), so additional assessments of fetal well-being may be used, or the baby delivered by caesarean section or instrumental vaginal birth. OBJECTIVES: To evaluate the effectiveness of continuous cardiotocography during labour. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (March 2006), CENTRAL (The Cochrane Library 2005, Issue 4), MEDLINE (1966 to December 2005), EMBASE (1974 to December 2005), Dissertation Abstracts (1980 to December 2005) and the National Research Register (December 2005). SELECTION CRITERIA: Randomised and quasi-randomised controlled trials involving a comparison of continuous cardiotocography (with and without fetal blood sampling) with (a) no fetal monitoring, (b) intermittent auscultation (c) intermittent cardiotocography. DATA COLLECTION AND ANALYSIS: Two authors independently assessed eligibility, quality and extracted data. MAIN RESULTS: Twelve trials were included (over 37,000 women); only two were high quality. Compared to intermittent auscultation, continuous cardiotocography showed no significant difference in overall perinatal death rate (relative risk (RR) 0.85, 95% confidence interval (CI) 0.59 to 1.23, n = 33,513, 11 trials), but was associated with a halving of neonatal seizures (RR 0.50, 95% CI 0.31 to 0.80, n = 32,386, nine trials) although no significant difference was detected in cerebral palsy (RR 1.74, 95% CI 0.97 to 3.11, n = 13,252, two trials). There was a significant increase in caesarean sections associated with continuous cardiotocography (RR 1.66, 95% CI 1.30 to 2.13, n =18,761, 10 trials). Women were also more likely to have an instrumental vaginal birth (RR 1.16, 95% CI 1.01 to 1.32, n = 18,151, nine trials). Data for subgroups of low-risk, high-risk, preterm pregnancies and high quality trials were consistent with overall results. Access to fetal blood sampling did not appear to influence the difference in neonatal seizures nor any other prespecified outcome. AUTHORS' CONCLUSIONS: Continuous cardiotocography during labour is associated with a reduction in neonatal seizures, but no significant differences in cerebral palsy, infant mortality or other standard measures of neonatal well-being. However, continuous cardiotocography was associated with an increase in caesarean sections and instrumental vaginal births. The real challenge is how best to convey this uncertainty to women to enable them to make an informed choice without compromising the normality of labour.

Cardiotocography↗