The fetal anomaly ultrasound only detects 65 to 81 % of the patients with congenital heart disease, making it the most common structural fetal anomaly of which a significant part is missed during prenatal life. Therefore, we need a reliable non-invasive diagnostic method which improves the predictive value for congenital heart diseases early in pregnancy. Fetal electrocardiography could be this desired diagnostic method. There are multiple technical challenges to overcome in the conduction of the fetal electrocardiogram. In addition, interpretation is difficult due to the organisation of the fetal circulation in utero. We want to establish the normal ranges and values of the fetal electrocardiogram parameters in healthy fetuses of 18 to 24 weeks of gestation. Women with an uneventful singleton pregnancy between 18 and 24 weeks of gestation are asked to participate in this prospective cohort study. A certified and experienced sonographist performs the fetal anomaly scan. Subsequently, a fetal electrocardiogram recording is performed using dedicated signal processing methods. Measurements are performed at two institutes. We will include 300 participants to determine the normal values and 95 % confidence intervals of the fetal electrocardiogram parameters in a healthy fetus. We will evaluate the fetal heart rate, segment intervals, normalised amplitude and the fetal heart axis. Three months postpartum, we will evaluate if a newborn is healthy through a questionnaire. Fetal electrocardiography could be a promising tool in the screening program for congenital heart diseases. The electrocardiogram is a depiction of the intimate relationship between the cardiac nerve conduction pathways and the structural morphology of the fetal heart, and therefore particularly suitable for the detection of secondary effects due to a congenital heart disease (hypotrophy, hypertrophy and conduction interruption).
Time-frequency analysis of heart rate variability (HRV) provides relevant clinical information. However, time-frequency analysis is very sensitive to artefacts. Artefacts that are present in heart rate recordings may be corrected, but this reduces the variability in the signal and therefore adversely affects the accuracy of calculated spectral estimates. To overcome this limitation of traditional techniques for time-frequency analysis, a new continuous wavelet transform (CWT)-based method was developed in which parts of the scalogram that have been affected by artefact correction are excluded from power calculations. The method was evaluated by simulating artefact correction on HRV data that were originally free of artefacts. Commonly used spectral HRV parameters were calculated by the developed method and by the short-time Fourier transform (STFT), which was used as a reference. Except for the powers in the very low-frequency and low-frequency (LF) bands, powers calculated by the STFT proved to be extremely sensitive to artefact correction. The CWT-based calculations in the high-frequency and very high-frequency bands corresponded well with their theoretical values. The standard deviations of these powers, however, increase with the number of corrected artefacts which is the result of the non-stationarity of the R-R interval series that were analysed. The powers calculated in the LF band turned out to be slightly sensitive to artefact correction, but the results were acceptable up to 20% artefact correction. Therefore, the CWT-based method provides a valuable alternative for the analysis of HRV data that cannot be guaranteed to be free of artefacts.
Background: Every day approximately 810 women die from complications related to pregnancy and childbirth worldwide. Around two thirds of these deaths happen in sub-Saharan Africa. One of the strategies to decrease these numbers is improving the quality of care by emergency obstetric simulation-based training. The effectiveness of such training programs depends on the program’s instructional design. Objective: This review gives an overview of studies about emergency obstetric simulation-based training and examines the applied instructional design of the training programs in sub-Saharan and Central Africa. Methods: We searched Medline, Embase and Cochrane Library from inception to May 2021. Peer-reviewed articles on emergency obstetric, postgraduate, simulation-based training in sub-Saharan and Central Africa were included. Outcome measures were categorized based on Kirkpatrick’s levels of training evaluation. The instructional design was evaluated by using the ID-SIM questionnaire. Findings: In total, 47 studies met the inclusion criteria. Evaluation on Kirkpatrick level 1 showed positive reactions in 18 studies. Challenges and recommendations were considered. Results on knowledge, skills, and predictors for these results (Kirkpatrick level 2) were described in 29 studies. Retention as well as decay of knowledge and skills over time were presented. Results at Kirkpatrick level 3 were measured in 12 studies of which seven studies demonstrated improvements of skills on-the-job. Improvements of maternal and neonatal outcomes were described in fifteen studies and three studies reported on cost-estimations for training rollout (Kirkpatrick level 4). Instructional design items were heterogeneously applied and described. Conclusions: Results of 47 studies indicate evidence that simulation-based training in sub-Saharan and Central Africa can have a positive impact across all four levels of Kirkpatrick’s training evaluation model. However, results were not consistent across all studies and the effects vary over time. A detailed description of instructional design features in future publications on simulation-based training will contribute to a deeper understanding of the underlying mechanisms that determine why certain training programs are more effective in improving maternal and neonatal healthcare outcomes than other.