Wyniki wyszukiwania - Biblioteka Nauki

1

Computerized fetal monitoring based on bioelectric signals from maternal abdomen

100%

Matonia A. , Jeżewski J. , Gacek A. , Kupka T. , Horoba K. , Wróbel J.

Journal of Medical Informatics & Technologies

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2002

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tom Vol. 4

MT37--47

EN

The paper presents an instrumentation set for effective diagnostics of early symptoms of fetal distress in high-risk pregnancy based on bioelectric signals recording. The representative database of records has been established that enabled the complex analysis of signals recorded on a surface of maternal abdomen. As an outcome, the effective algorithms have been developed for processing both the fetal electrocardiogram and the signal of electrical activity of a uterine muscle. This allowed the development of unique diagnostic system based on external biosignal measurement module connected to the standard personal computer. In this system, like in a classical fetal monitor, the fetal heart rate (FHR) signal together with contraction activity signal of uterine muscle and fetal movement become an essential source of information on fetal condition. In addition, there is a possibility for spectral analysis of FHR signal as well as a morphology assessment of fetal ECG signal.

2

Coincidence of maternal and fetal QRS complexes in view of fetal heart rate determination

100%

Kupka T. , Jeżewski J. , Matonia A. , Wróbel J. , Horoba K.

Journal of Medical Informatics & Technologies

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2002

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tom Vol. 4

MT49--55

EN

Indirect fetal electrocardiography is a developing diagnostic method in perinatal medicine. Signals of electrical activity being recorded from maternal abdomen surface contain more information than in till now used method of mechanical heart activity measurement based on ultrasound signals. The main problem relies on separation of basic useful component from a signal containing also dominant maternal electrocardiogram and muscles activity artifacts. The algorithms of maternal electrocardiogram suppression via subtraction are commonly used. Although regarding their complexity, these algorithms have limited applicability in systems for long-term monitoring of fetal heart activity. Other solution relies on simple blanking of maternal QRS complexes. However, in case of coincidence of fetal and maternal QRS complexes, this leads to partial loss of information about fetal heart rate variability. For evaluation of how often such coincidence of both complexes takes place, the algorithm has been developed which is described in this paper.

3

Inconsistency in evaluation of clinical patterns in fetal heart rate waveforms

100%

Jeżewski J. , Horoba K. , Wróbel J. , Gacek A.

Journal of Medical Informatics & Technologies

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2002

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tom Vol. 4

MT27--35

EN

Acceleration and deceleration patterns in fetal heart rate (FHR) are widely used as an assessment of fetal condition. The basis for both visual and automated quantitative analysis is correctly determined fetal heart rate baseline. There are many methods for automated fetal heart rate baseline estimation. Since there are no definitive criteria or "gold standard" to evaluate algorithms for baseline determination, a clinical expert could be considered as a reference. Taking into account that not the shape of baseline itself but the results of quantitative analysis obtained using this baseline are important, we stated that such evaluation should be done only on the basis of comparison of effects - the recognized accelerations and decelerations. However, the first step for such comparison is to check how well expert meets established FIGO definition of accelerations and decelerations patterns in FHR trace. The paper presents a method for evaluation of expert's interpretation of these definitions. Two indices describing the inconsistency among fetal monitoring system and experts have been defined. The results obtained indicate the essential differences in procedure of accelerations/decelerations recognition by the computerized system and human expert.

4

Improving the periodicity measurement in fetal heart activity signal

100%

Roj D. , Wróbel J. , Horoba K. , Przybyła T. , Kupka T.

Journal of Medical Informatics & Technologies

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2010

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tom Vol. 16

19--26

EN

In this paper we discussed the influence of preliminary processing of the ultrasound Doppler signal on accuracy of the fetal heart rate estimation as well as on reliability of the FHR instantaneous variability assessment. We attempted to develop an optimal processing channel of US Doppler signal in order to measure the periodicity of fetal heart activity with accuracy as close as possible to that ensured by FECG. The FHR values determined from the US signal were compared to the reference data obtained from direct FECG. In a final evaluation we used the parameters describing the FHR variability as the clinically important signal features being the most sensitive to any periodicity inaccuracy. The results proved that an application of proposed algorithms improves the accuracy of interval measurements and FHR instantaneous variability assessment in relation to the new-generation fetal monitors.

5

Evaluation of predictive capabilities of quantitative cardiotocographic signal features

100%

Czabański R. , Jeżewski M. , Roj D. , Szaszkowski Z. , Kupka T. , Wróbel J.

Journal of Medical Informatics & Technologies

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2010

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tom Vol. 16

11--17

EN

Cardiotocography (CTG) is the main method of assessment of the fetal state during pregnancy and labour used in clinical practice. It is based on quantitative analysis of fetal heart rate, fetal movements and uterine contractions signals. The evaluation of the CTG signals can be made using criteria recommended by International Federation of Obstetrics and Gynecology. Nevertheless, the diagnosis verification is possible only after the delivery on the basis of newborn assessment. In the proposed work we evaluated the capacity of quantitative analysis of CTG traces in predicting fetal outcome. The relationship between CTG signal features and attributes of fetal outcome was assessed on the basis of ROC curves analysis. The obtained results indicate the adequate predictive capabilities of the selected CTG features especially for fetal outcome assessed with Apgar score and suggest the necessity of applying the criteria for the CTG traces evaluation that are related to the gestational age. Our study also shows the value of the CTG monitoring as a screening procedure providing appropriate confirmation of fetal wellbeing.

6

Fuzzy system for evaluation of fetal heart rate signals using FIGO criteria

100%

Czabański R. , Jeżewski M. , Wróbel J. , Jeżewski J. , Horoba K.

Journal of Medical Informatics & Technologies

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2009

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tom Vol. 13

189--194

EN

Cardiotocography is a biophysical method of fetal monitoring during pregnancy and labour. It is mainly based on recording and analysis of fetal heart activity. The computerized fetal monitoring systems provide the quantitative description of the recorded signals but the effective methods supporting the conclusion generation are still needed. The evaluation of the signal can be made using criteria recommended by FIGO. Nevertheless, the quantitative description of the traces is inconsistent with qualitative nature of the obstetric knowledge. Therefore, we applied the fuzzy system based on Takagi-Sugeno-Kang model to evaluate and classify signals. FIGO guidelines were used for developing a set of fuzzy conditional rules defining the system performance. The proposed system was evaluated using data collected with computerized fetal surveillance system – MONAKO. The classification results confirm the improvement of the fetal state evaluation quality while using the proposed fuzzy system support.

7

Comparison of instantaneous fetal heart rate extracted from abdominal and direct fetal electrocardiograms

100%

Matonia A. , Kupka T. , Jezewski J. , Momot A. , Jeżewski M. , Bernys M.

Journal of Medical Informatics & Technologies

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2012

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tom Vol. 19

101--107

EN

This work is an attempt to assess the reliability of indirect abdominal electrocardiography as an alternative technique of fetal monitoring. As a reference signal we used the simultaneously acquired direct fetal electrocardiogram. Each recording consisted of four signals acquired from maternal abdomen and the reference signal acquired directly from fetal head. The first stage of our study concerned the signal loss episodes. In order to reduce the influence of incorrectly detected R-waves, some certain validation rules were applied. In the second stage, the corresponding intervals determined on basis of both acquisition methods were matched and the accuracy of fetal heart rate measurement was evaluated. Although the accuracy of abdominal electrocardiography turned out to be slightly lower than reported for ultrasound method, it still has some unique features deciding of its prevalence in a certain circumstances.

8

Automated detection of fetal movements in Doppler ultrasound signals versus maternal perception

100%

Wróbel J. , Kupka T. , Horoba K. , Matonia A. , Roj D. , Jeżewski J.

Journal of Medical Informatics & Technologies

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2014

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tom Vol. 23

43--50

EN

Analysis of movement activity is important since it enables detection of nonreactive fetal heart rate recordings. The aim of the study was to develop an algorithm for automated detection of the fetal movement activity (actogram), based on analysis of the Doppler ultrasound signal, and to evaluate a reliability of the actogram as a source of information about the fetal movements. Bandpass filtering (20-80 Hz) was used to separate the actogram signal describing the fetal movement activity. Simultaneously there were recorded the markers of fetal movements perceived by mother, being the reference information. For the determination of the binary actogram, the authors proposed an algorithm in which the classification threshold was estimated at the beginning of each recording and was adaptively modified during its duration. The algorithm ensured detection of up to 89% of movement episodes corresponding to movements perceived by mother. At the same time almost as high number of episodes not related to the reference information was recognized. Obtained results revealed that the automated analysis of fetal movements is characterized by much higher sensitivity of movement episode detection compared to the maternal perception.

9

Improving fetal heart rate signal interpretation by application of myriad filtering

100%

Wróbel J. , Horoba K. , Pander T. , Jeżewski J. , Czabański R.

Biocybernetics and Biomedical Engineering

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2013

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tom Vol. 33, no. 4

211--221

EN

Analysis of the fetal heart rate (FHR) signal is aimed at detection of clinically important patterns like bradycardia or tachycardia, accelerations and decelerations, as well as quantification of instantaneous FHR variability. Automated pattern recognition methods are based on estimation of so-called FHR baseline. It is a common opinion that the baseline estimation algorithm determines the efficiency of an entire process of quantitative signal analysis. Automated methods for baseline determination have been continuously improved for many years since there are still new classes of FHR signals being identified, for which the previous methods fail. The new method proposed for the baseline estimation is based on the weighted myriad filtering. The application of this method required filter parameter selection ensuring its operation according to clinical guidelines for baseline estimation. A very important feature of the myriad filtering is that there is no need for preliminary interpolation of signal loss segments. Our new algorithm was tested against two other methods. Thirty one-hour FHR recordings were selected for the analysis. Quantitative inconsistency was measured using differences between corresponding baseline samples. Additionally, the baselines were evaluated as regards their influence on identification of the acceleration and deceleration patterns. Obtained results allow us to conclude that the new algorithm delivers more reliable baselines particularly for signals with specific changes of the basal FHR level which has been recognized as difficult for baseline estimation.

10

Instrumentation for fetal monitoring - improvement in Doppler ultrasound technology

84%

Jeżewski J. , Wróbel J. , Horoba K. , Gacek A.

Journal of Medical Informatics & Technologies

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2001

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tom Vol. 2, Part. 2

MT17--MT26

EN

The most common noninvasive method of measuring fetal heart rate (FHR) utilizes pulsed Doppler ultrasound monitors. Ultrasound-derived fetal heart intervals are obtained from mechanical movements of the heart valves or heart wall. As distinct from the direct cardiac cycle recording, the analysis of the multi-phase movement process involves difficulties in precise measurement of cardiac interval distances. Linked both to the analog channel and the digital processing from today’s monitors, different factors influencing the quality of the FHR trace are presented. An emphasis is put on autocorrelation techniques for extraction of periodic signal from a noisy background. Two basic forms of autocorrelation function, the autocorrelation with adaptive window selection and crosscorrelation with a changeable template are discussed in detail.

11

Monitoring of fetal movements based on actogram signal analysis

84%

Kupka T. , Matonia A. , Wróbel J. , Horoba K. , Jeżewski J.

Journal of Medical Informatics & Technologies

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2004

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tom Vol. 8

MM119--128

EN

At present, biophysical fetal monitoring relies mainly on evaluation of a fetal heart rate (FHR). Absence of the FHR variability indicates central nervous system depression associated with hypoxia. The analysis of fetal heart rate segments identified with the aid of information on fetal movement activity provides much better results than analysis of the whole signal. Automatic recording of the fetal movement activity in a form of actogram signal provided by new models of fetal monitors becomes very common. For evaluation of information content of the actogram signal, the measurement instrumentation has been developed. The examined group comprised 20 patients and the total time of recording was 10 hours. Correlation between movements observed by clinical experts on ultrasonographic image and actogram trace recorded by fetal monitor was analysed. Although for head, arms, legs and trunk movements just visual analysis let observe their correlation with actogram signal, but in case of breathing movement no correlation was noted. Depending on movement type the detection efficiency was in range from 54 % to 80 %.

12

Fetal heart rate estimation using fractional Fourier transform and wavelet analysis

84%

Jaba Deva Krupa A. , Dhanalakshmi S. , Sanjana N. L. , Manivannan N. , Kumar R. , Tripathy S.

Biocybernetics and Biomedical Engineering

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2021

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tom Vol. 41, no. 4

1533--1547

EN

Objective: Monitoring fetal cardiac activity during pregnancy is a critical part of assessing the fetus’s health. Non-invasive fetal electrocardiogram (NIFECG) is a safe emerging fetal cardiac monitoring approach receiving considerable interest. This paper proposes an effective way to separate the fetal ECG signal from the single-channel abdominal ECG signals. Methods: The paper proposes a novel algorithm based on time-frequency analysis combining fractional Fourier transform (FrFT) and wavelet analysis to extract fetal ECG from abdominal signals at higher accuracy. The abdominal signals acquired from pregnant women are preprocessed and subjected to suppressing maternal ECG using fractional Fourier transform and maximum likelihood estimate. The estimated maternal signal is removed from the abdominal ECG. The residue is processed using wavelet decomposition to obtain a clean fetal ECG and calculate fetal heart rate. Results: The proposed algorithm’s performance is validated using signals from the Daisy database and Physionet challenge 2013 set-a dataset. Real-time signals acquired using Powerlab data acquisition hardware are also included for validation. The obtained results show that the proposed algorithm can effectively extract the fetal ECG and accurately estimate the fetal heart rate. Conclusion: The proposed method is a promising and straightforward algorithm for FECG extraction. Fractional Fourier transform maps the time domain abdominal signal into the fractional frequency domain, distinguishing the fetal and maternal ECG. The Wavelet transform can efficiently denoise the residue abdominal signal and provides a clean fetal ECG. The proposed approach achieves 98.12% of accuracy, 98.85% of sensitivity, 99.16% of positive predictive value, and 99.42% of F1 measure.

13

The influence of window size of autocorrelation function on fetal heart rate variability measurement using the Doppler ultrasound signal

84%

Roj D. , Fuchs T. , Przybyła T. , Jeżewski M. , Matonia A. , Gacek A.

Journal of Medical Informatics & Technologies

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2008

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tom Vol. 12

111--116

EN

Commonly used noninvasive fetal monitoring is based on fetal heart rate (FHR) variability analysis of the Doppler ultrasound signal coming from the mechanical activity of the fetal heart. Estimation of periodicity of acquired signals using the autocorrelation technique is very important. The determination of cardiac intervals using the Doppler signal is more difficult than in electrocardiography, where the R-waves are evident. We investigated the influence of the autocorrelation window size on the FHR variability analysis. The indices describing the FHR variability calculated for signals obtained using two different autocorrelation techniques with various window lengths were compared with the reference ones obtained from fetal electrocardiogram. The optimal window was a compromise between artifacts resistance and the averaging level of instantaneous variability.

14

Combined analysis of fetal electrocardiogram and systolic time intervals

84%

Matonia A. , Jeżewski J. , Kupka T. , Horoba K. , Wróbel J. , Widera M.

Journal of Medical Informatics & Technologies

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2003

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tom Vol. 6

IT27--34

EN

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.

15

A routing protocol for wireless network of bedside monitors in fetal surveillance system

84%

Seredynski R. , Horoba K. , Roj D. , Bernys M. , Przybyla T. , Jezewski J.

Journal of Medical Informatics & Technologies

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2012

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tom Vol. 21

27--33

EN

The paper presents the methodology of wireless network design, developed according to the requirements originating from existing wired fetal surveillance systems. The proposed network structure is based on popular radio frequency modules, operating in 433/866MHz band. The described solution is a simple and cost effective alternative to the wired networks, and it will vastly increase the mobility of fetal monitors. The authors also describe software tools which were designed for this purpose and the results of simulations performed on their basis.

16

Fetal state assessment using fuzzy analysis of fetal heart rate signals - Agreement with the neonatal outcome

84%

Czabański R. , Jeżewski J. , Horoba K. , Jeżewski M.

Biocybernetics and Biomedical Engineering

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2013

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tom Vol. 33, no. 3

145--155

EN

Fetal monitoring is based on analysis of fetal heart rate signal. Visual interpretation is difficult so computer-aided systems for quantitative analysis are commonly used. The clinical interpretation guidelines provided by FIGO (Fédération Internationale de Gynécologie et d'Obstétrique) were used to develop the weighted fuzzy scoring system for qualitative assessment of the fetal state. In this work, agreement of the fuzzy classification system with the neonatal outcome assessment was analyzed. Various datasets were evaluated, depending on interpretation method of the signals which were recorded from patients. The obtained results confirmed possibility of the efficient fetal state assessment using the fuzzy inference method proposed.

17

Application of generalized filters for estimation of fetal heart rate baseline

84%

Pander T. , Przybyla T. , Wrobel J. , Jezewski J. , Roj D.

Journal of Medical Informatics & Technologies

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2011

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tom Vol. 17

73--79

EN

This paper addresses the problem of impulsive noise cancellation in digital signal area. The myriad and meridian filters are the type of robust filters which are very useful in suppressing the impulsive type of noise. The cost functions of theses filters have very similar structure. In this paper the generalized filter based on Lp norm is presented. The proposed filter operates in a wide range of impulsive noise due to the proper adjustment of p in the Lp norm. The presented filter is applied to suppress an impulsive noise in fetal heart rate (FHR) signal. Simulation results confirm the validity of the proposed filter.

18

Fuzzy prediction of fetal acidemia

84%

Czabański R. , Roj D. , Jeżewski J. , Horoba K. , Jeżewski M.

Journal of Medical Informatics & Technologies

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2011

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tom Vol. 17

81--87

EN

Cardiotocography is the primary method for biophysical assessment of a fetal state. It is based mainly on the recording and analysis of fetal heart rate signal (FHR). Computer systems for fetal monitoring provide a quantitative description of FHR signals, however the effective methods for their qualitative assessment are still needed. The measurements of hydronium ions concentration (pH) in newborn cord blood is considered as the objective indicator of the fetal state. Improper pH level is a symptom of acidemia being the result of fetal hypoxia. The paper proposes a twostep analysis of signals allowing for effective prediction of the acidemia risk. The first step consists in the fuzzy classification of FHR signals. The task of fuzzy inference is to indicate signals that according to the FIGO guidelines represent the fetal wellbeing. These recordings are eliminated from the further classification with Lagrangian Support Vector Machines. The proposed procedure was evaluated using data collected with computerized fetal surveillance system. The classification results confirmed the high quality of the proposed fuzzy method of fetal state evaluation.

19

Direct assessment of the fetal heart rate from abdominal composite recordings

67%

Moslem B. , Bazzi O. , Khalaf J. , Diab M. O.

Journal of Medical Informatics & Technologies

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2013

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tom Vol. 22

143--149

EN

In respect to the main goal of our ongoing work for analyzing fetal electrocardiogram (FECG) signals for monitoring the health of the fetus, we investigate in this paper the possibility of extracting the fetal heart rate (FHR) directly from the abdominal composite recordings. Our proposed approach is based on a combination of Independent Component Analysis (ICA) and least mean square (LMS) adaptive filter. The FHR of the estimated FECG signal is finally compared to a reference value extracted from a FECG signal recorded by using a spiral electrode attached directly to the fetal scalp. The experimental results show that FHR can be successfully evaluated directly from the abdominal composite recordings without the need of using any external reference signal.