This work was aimed at assessment of usability of Doppler ultrasound method for the analysis of fetal heart rate variability at a level of single heart beats. The purpose of this study was to check if today fetal monitors provide the signal of accuracy comparable with an electrocardiography method. The virtual instrumentation software for measurement system and processing of acquired signals was implemented using LABVIEW environment. The results obtained reveal that accuracy of today monitors which use Doppler ultrasound technique is sufficient for visual analysis of the FHR traces. However, for the computerized analysis at a beat-to-beat level, this accuracy is below the acceptable value.
Cardiotocography as a simultaneous recording of fetal heart rate (FHR) and uterine contraction activity is a basic method of evaluation of fetal condition. Correct variability of the fetal heart rate is an indirect sign of adequate oxygenation of a fetus. Unfortunately, the reverse case is not always true, signs suggesting pathological changes can also appear in recording when the fetal is not at risk. The cardiotocography shall then be recognized as a more screening than diagnostic method. It will be interesting to develop a non-invasive method being complementary to routine cardiotocography. This method should allow the adequate prediction of a bad neonatal outcome when the test is abnormal. The paper shows the system that makes possible cardiotocograms analysis in parallel with the assessment of additional parameters determined from comparison of mechanical and electrical fetal heart activity signals. The studies are aimed at development of set of parameters that are high correlated with clinical outcome.
We propose to tackle the problem of maternal abdominal electric signals decomposition with a combined application of independent component analysis and projective or adaptive filtering. The developed method is employed to process the four-channel abdominal signals recorded during twin pregnancy. These signals are complicated mixtures of the maternal ECG, the ECGs of the fetal twins and noise of various origin. Although the independent component analysis cannot separate the respective signals, the proposed combination of the methods deals with this task successfully. A simulation experiment confirms high efficiency of this approach.
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