Wyniki wyszukiwania - BazTech

1

Changes in the central and peripheral circulatory system in response to the cold: own studies using impedance plethysmography and Doppler ultrasound

Łastowiecka-Moras E., Kozyra-Pydyś E.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 4

494-500

EN

The aim of the study was to determine the cardiovascular response to continuous (4 °C for 60 min) and intermittent (10 min at 4 °C and 10 min at room temperature alternately) exposure to the cold in 30 healthy young men. The subjects were equipped with a set of identical clothing (insulation 2.1 clo) and during the stay in the chamber and outside performed the same activities, i.e., walking on a treadmill at a speed of 0.5 km/h. The tests included assessing the central circulatory system using the Holter system and assessing the peripheral circulatory system using impedance plethysmography and Doppler ultrasound. The analysis of the parameters that describe the central and peripheral circulation poses a difficulty in determining which variant of exposure constitutes a greater load on the circulatory system. It should be noted that even the conditions used in the study may cause adverse effects in the cardiovascular system.

2

Analiza wybranych czynników aparaturowo-technicznych wpływających na wyniki badań USG

Niemasek K., Tutaj J.

Aktualne Problemy Biomechaniki

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2013

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z. 7

125--130

PL

W artykule przedstawiono analizę wpływu ugięcia wiązki Dopplera widmowego w zakresie ±10°, w stosunku do wiązki wykorzystywanej do uzyskania obrazu B, na wyniki otrzymanych parametrów przepływu krwi w badaniach ultrasonograficznych tętnic szyjnych wspólnych za pomocą metody Duplex Doppler w połączeniu z kolorowym obrazowaniem przepływu krwi. Analiza ta pozwala na obserwację zmian otrzymanych parametrów w grupie kobiet i mężczyzn wynikających z nachylenia wiązki dopplerowskiej.

EN

The article presents an analysis of the impact of the beam deflection of the Doppler spectrum in the range of ±10 °, relative to the beam used to obtain an image B, the results of the parameters obtained in studies of blood flow in carotid artery ultrasonography using duplex Doppler methods in conjunction with color flow imaging blood. This analysis allows to observe the changes in the parameters obtained in the group of men and women under the Doppler beam tilt.

3

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

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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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.

4

The fetal heart rate estimation based on continuous ultrasonic Doppler data

Kret T., Kałużyński K.

Biocybernetics and Biomedical Engineering

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2006

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Vol. 26, no. 3

49-56

EN

Two methods to compute the fetal heart rate based on the analysis of Doppler signals obtained using continuous wave ultrasound were studied. The first uses bandpass filtering, directional signal separation and computation of the autocorrelation coefficient of the envelope of a single directional Doppler signal. The other uses discrete wavelet decomposition and reconstruction of a single directional signal with Daubechies db 10 wavelet family, with subsequent computation of the autocorrelation coefficient of the envelope of the reconstructed signal details for various scales. The results indicate that the discrete wavelet decomposition method is a suitable tool for fetal heart rate determination. It results in a more consistent fetal heart rate trace than the bandpass filtering approach.

5

Monitoring of fetal movements based on actogram signal analysis

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

Journal of Medical Informatics & Technologies

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2004

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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 %.

6

Ultrasonographic validation of the software system for online analysis of ultrasonic Doppler signals of fetal activity

Kret T., Kałużyński K.

Elektronika : konstrukcje, technologie, zastosowania

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2004

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Vol. 45, nr 8-9

127-129

EN

Fetal motor activity (pseudobreathing movements, trunk and limb movements) and the fetal heart rate are important indicators of fetal well-being. The software developed using the LabVIEW environment processes in real time Doppler signals acquired from the CW fetal Doppler activity monitor via the PC sound card. Displacements of the structures, velocities and accelerations of these displacements as well as histograms of the velocities and accelerations are computed. The fetal heart rate and breathing movements are determined. The software performance was tested against ultrasonographic recordings. Four pregnancies were submitted to a 15-20 minutes long examination. The ultrasonographic images and Doppler quadrature data were taped simultaneously with Hi-Fi video recorder, then used as signal source for laboratory tests of the software. The movements detected with the software environment were compared with the concurrent USG images. The experiments show that the elaborated software is capable of detecting different kinds of fetal movements. Some artifacts, specifically those resulting from maternal movements, may be eliminated on the basis of their amplitude. The software is a promising diagnostic tool for obstetrics.

PL

Aktywność ruchowa płodu (ruchy pseudooddechowe, ruchy tułowia i kończyn) oraz rytm serca są ważnymi wskaźnikami stanu płodu. Oprogramowanie stworzone z użyciem środowiska LabVIEW przetwarza, w czasie rzeczywistym, sygnały dopplerowskie uzyskiwane z monitora aktywności ruchowej płodu z falą ciągłą przez kartę dźwiękową komputera PC. Wyznaczane są ruchy płodu, prędkości i przyśpieszenia tych ruchów, jak również histogramy prędkości i przyśpieszeń. Wykrywane są rytm serca płodu, jak również ruchy pseudooddechowe. Wyniki uzyskiwane przez oprogramowanie porównano z wynikami obserwacji ultrasonograficznej. Cztery przypadki ciąż bez powikłań zostały poddane 15-20 minutowemu badaniu. Obrazy ultrasonograficzne i kwadraturowe sygnały dopplerowskie były rejestrowane jednocześnie z użyciem magnetowidu Hi-Fi, następnie zostały użyte jako źródło sygnału podczas testów oprogramowania w warunkach laboratoryjnych. Opracowane oprogramowanie wykrywa różne rodzaje ruchów płodu. Niektóre zakłócenia, szczególnie te wynikające z ruchów matki, mogą być eliminowane w oparciu o ich amplitudę. Oprogramowanie jest obiecującym narzędziem w diagnostyce położniczej.

7

Online analysis of the ultrasonic Doppler signals of the fetal motor activity in the LabVIEW environment

Kret T., Kałużyński K.

Biocybernetics and Biomedical Engineering

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2004

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Vol. 24, no. 2

41-49

EN

Fetal motor activity and the fetal heart rate are important indicators of fetal well-being. The motor activity consist of pseudobreathing movements, trunk and limb movements. These movements can be detected using the ultrasonic Doppler method. The software developed using the LabVIEW environment processes in real time Doppler signals acquired via the PC sound card. Displacements of the structures, velocities and accelerations of these displacements as well as histograms of the velocities and accelerations are computed. Spectral analysis of the chest displacement signal allows determining the rhythm of pseudobreatching movements. The autocorrelation function is used to compute the fetal heart rate. The software was tested on simulated signals and real fetal Doppler signals.

8

Instrumentation for fetal monitoring - improvement in Doppler ultrasound technology

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

Journal of Medical Informatics & Technologies

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2001

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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.