WO2023006133A1

WO2023006133A1 - Method of monitoring movement of fetus and a device for monitoring movement of fetus

Info

Publication number: WO2023006133A1
Application number: PCT/CZ2022/050068
Authority: WO
Inventors: Filip STUDNIČKA; Jan Šlégr; Petr ŠEBA; Richard Cimler; Jitka Kühnová; Jan Matyska; Damián BUŠOVSKÝ; Jan Štěpán; Marian KACEROVSKÝ
Original assignee: Univerzita Hradec Králové; Fakultní nemocnice Hradec Králové
Priority date: 2021-07-30
Filing date: 2022-08-01
Publication date: 2023-02-02
Also published as: CZ2021360A3; CZ309588B6

Abstract

The object of the invention is a method of operation of a device (1) for monitoring movement of fetus in utero. The device comprises a pair of sensors that monitor mechanical excitations and heart parameters. The sensors (3, 4) are placed on the body of the patient (2), the first in the upper half of the body, the second in the region below the abdominal bifurcation. After detection of mechanical excitations and parameters of the aorta, a time parameter describing the relationship between the mechanical excitations and parameters is determined. By further processing of the time parameter by the computing unit, movement of fetus in utero is detected. The movement of the fetus compresses the aorta of the mother, which affects the dynamics of blood flow in the body. As a result the time parameter does not have a constant value and by studying it and processing its values over a longer period of time it is possible to detect movement of fetus. The device may include an alert unit that will alert the medical personnel if an arrest of movement of fetus is detected.

Description

Method of monitoring movement of fetus and a device for monitoring movement of fetus

Technical Field

The invention relates to a diagnostic device for monitoring peristalsis of organs of the gastrointestinal tract or movement of fetus in utero.

Background of the Invention

Heart pulse or pressure is a frequently used source of physiological data, the analysis of which can be used to diagnose a patient’s condition or to evaluate the effect of treatment. One of the most common methods is listening to the heart with a phonendoscope, which can be used to determine the heart rate. Blood pressure is determined by a tonometer. Heart rate can also be measured non-invasively using a finger oximeter. More detailed information about the heart activity provides, for example, the ECG method.

The document US 10,335,050 B2 describes a device for determining the propagation velocity of a cardiac pulse wave. The device comprises at least two pulse wave sensors, where one sensor is placed on a finger of the hand and the other sensor is placed on a toe of the foot of the patient, and a computing unit adapted to determine the time at which a given pulse wave arrives to the finger of the hand and to the toe of the foot of the patient. The computing unit works with the time difference measured between pulse wave detections, which is then used to determine the risk of a cardiac event using the patient’s height and age. The document does not describe the methodology of data processing that would allow for monitoring of peristalsis of the patient’s gastrointestinal tract or movement of the fetus in utero.

The document JP09081047 describes a device measuring an R wave signal using an ECG placed above the level of the abdomen of the patient being monitored, and a pulse wave signal on a finger of the hand. By processing the measurements it is possible to obtain information about the transition time of the pulse wave of the aorta. However, without a sensor placed on the lower body, it is not possible to determine the degree of peristalsis of the patient’s gastrointestinal tract.

Summary of the Invention

The above shortcomings of the state of the art are at least partially eliminated by a device for monitoring movement of fetus. The device comprises a first sensor adapted to be placed in the region of the upper half of the body, a second sensor adapted to be placed in the region below the abdominal bifurcation, and a computing unit communicatively connected to the first sensor and the second sensor. The first sensor is adapted to detect at least one mechanical parameter of the aorta by the first sensor. The second sensor is adapted to detect mechanical excitation of the aorta. The computing unit is then adapted to determine the time parameter, which describes the time relationship between the mechanical parameter and the mechanical excitation. The advantage of the present device lies in the accurate detection of movement of fetus based on the processing of the time parameter.

The first sensor is embodied as an electrocardiograph, or together with the second sensor it is embodied as a piezoelectric sensor or a strain gauge.

The device further comprises an AD converter electrically connected to the first and second sensors and the computing unit. Preferably the signal is amplified by an amplifier before processing.

The device further preferably comprises an alert mechanism and a communication peripheral communicatively connected to the alert mechanism, where the alert mechanism is adapted to alert medical personnel in the event of detection of arrest of movement of the fetus.

The above shortcomings of the state of the art are at least partially eliminated by a method for monitoring movement of the fetus using the above mentioned device. The device comprises a first sensor adapted to be placed in the region of the upper half of the body, a second sensor adapted to be placed in the region below the abdominal bifurcation, and a computing unit communicatively connected to the first sensor and the second sensor. The method of operation of the device comprises the following steps:

- detection of at least one mechanical parameter of the aorta by the first sensor; - detection of mechanical excitation of the aorta by the second sensor, where the mechanical parameter measured detected by the first sensor and the mechanical excitation detected by the second sensor correspond to the same heartbeat;

- and determination of the time parameter describing the time relationship between the mechanical parameter and the mechanical excitation by the computing unit.

The advantage of the present method lies in the accurate detection of movement of fetus based on the processing of the time parameter.

Preferably, the second sensor is embodied as a piezoelectric sensor or strain gauge and detects the pulse wave of the aorta, which is a mechanical excitation of the aorta. The first sensor is embodied as an electrocardiograph, where the mechanical parameter of the aorta is its QRS complex. The time parameter is the time difference between the detection of the R wave by the first sensor and the detection of the pulse wave of the aorta by the second sensor.

Alternatively, the first sensor can be embodied as a piezoelectric sensor or strain gauge, wherein the mechanical parameter of the aorta is its pulse wave. The time parameter is then the time difference between the detection of the pulse wave of the aorta by the first sensor and the second sensor.

Preferably, the method is performed for 30-1800 s, therefore, the present method of operation of the device for monitoring movement of fetus does not restrict the patient during the measurement in the long term and does not represent a significant interference with their comfort.

The method further preferably comprises steps performed by the computing unit:

- creation of a time series of the time parameter values,

- determination of the spectral density of the time parameter values

- and indication of movement of fetus.

These steps have the advantage of automatically indicating the arrest of movement of fetus in utero. This can be further monitored by an alert mechanism that alerts the attending staff in the event of detection of an arrest of movement of fetus Description of Drawings

A summary of the invention is further clarified using exemplary embodiments thereof, which are described with reference to the accompanying drawings, in which: Fig. 1 - shows a device for monitoring movement of fetus in utero; Fig. 2 - shows QRS complex of the aorta;

Fig. 3 and 4 - show the waveform of signals measured by the first and second sensor; Fig. 5 and 6 - the spectral dependence of the processed signal is plotted;

Fig. 7 - the first time series obtained by the CTG method with the movement of the fetus marked by black rectangles is plotted; Fig. 8 - the output of the CWT method applied to the first Cartan curvature of the processed signal, where the horizontal axis symbolizes time values, and the vertical axis symbolizes a magnitude of the signal, is plotted. Exemplary Embodiments of the Invention

The invention will be further clarified using exemplary embodiments with reference to the respective drawings, which, however, have no limiting effect on the scope of protection.

In the first exemplary embodiment shown in Fig. 1 a device 1 for monitoring movement of fetus comprises a first sensor 3 adapted to be placed in the region of the upper half of the body of the patient 2 above the level of the heart, for example, on the hand, arm, fingers, in the neck region, or on the head, and a second sensor 4 adapted to be placed in the region of the lower half of the body of the patient 2 below the level of the heart, for example, behind the abdominal bifurcation in the direction of blood flow through the arteries, e.g. on the thigh, calf, foot, or toes, and a computing unit 5 electrically connected to the first and second sensors 3, 4.

The first sensor 3 is adapted to detect a mechanical parameter of the aorta. The second sensor 4 is adapted to detect a mechanical excitation of the aorta or induced by the aorta or the pulse wave of the aorta. The pulse wave of the aorta corresponds to a single heartbeat, during which blood is displaced from the heart into the aorta and then into the individual arteries and other vessels. The displacement and transport of blood are associated with an increase in blood pressure in the vessels, which decreases in the second phase of the cardiac cycle. The peak of the pulse wave corresponds to the highest value of pressure reached, while the minimum of the pulse wave corresponds to the lowest value of blood pressure. In the same way, mechanical excitations occur during the heart pulse and propagate through the individual vessels. The first sensor 3 is embodied either as a mechanical sensor of the excitation caused by the pulse wave of the aorta, or in an alternative embodiment the first sensor 3 is embodied as an electrocardiograph. The second sensor 4 is embodied as a mechanical sensor of the excitation caused by the pulse wave of the aorta. In case of mechanical embodiment of the sensors 3, 4, the sensors 3, 4 may be in the form of a piezoelectric sensor, where the pulse waveform causes deformation of the crystal in the sensor and thus generates electrical voltage. Another option for a mechanical sensor embodiment is to use a strain gauge.

As an example, the device 1 for monitoring peristalsis of organs further comprises a first amplifier 7 electrically connected to the first sensor 3, and a second amplifier 7 electrically connected to the second sensor 4. The amplifiers 7 are used to amplify the output signals obtained by the first and second sensors 3, 4. The device 1 for monitoring peristalsis of organs further comprises at least one AD converter 6 for converting the analogue signal obtained by the first and second sensors 3, 4 into a digital signal. The AD converter 6 is electrically connected to the computing unit 5 to which it sends the converted digital signal. Alternatively, two AD converters 6 can be used, one for each sensor 3, 4.

In an exemplary embodiment, where the first sensor 3 is embodied as an electrocardiograph, the mechanical parameter of the aorta is the QRS complex shown in Fig. 2, which describes the contraction of the ventricular musculature of the heart. The duration of the signal corresponding to the QRS complex ranges from 75-105 ms. The monitored parameter is then the R wave, which is the highest positive wave recorded on the electrocardiograph and corresponds to the pulse of the aorta.

The amplified and converted signal obtained by the first and second sensors 3, 4 corresponds to the pulse waveform of the aorta, where both waveforms, or the waveform measured by the first sensor 3 and the second sensor 4, belong to the same heartbeat. The amplified and converted signal is then processed by the computing unit 5. Both signals have a similar waveform, as can be seen in Fig. 3, however, they are slightly delayed to each other, which is due to the placement of the first and second sensors 3, 4, which are usually at different distances from the heart. Alternatively, it is possible to work only with the detection of the pulse wave itself instead of sensing entire waveform thereof. In this case, the pulse corresponding to the same heartbeat is detected by one sensor at a certain time and the other sensor detects this pulse with a certain time delay. The signals corresponding to the pulse waveform are then processed by the computing unit 5. In Fig. 3 and 4, the waveform of signals measured by the first sensor 3 (blue) and the second sensor 4 (orange) is shown in an exemplary embodiment, in which both sensors 3, 4 are embodied as mechanical sensors. The waveform of the signals corresponds to the mechanical excitation induced by the pulse wave of the aorta. In Fig. 3 and 4, it is clear that both signals have a very similar trend, however, they show a slight delay with respect to each other. Signal processing means determination of time parameter describing time relationship between the mechanical parameter of the aorta and the mechanical excitation of the aorta by subtracting the pulse waveforms detected by the first sensor 3 and the second sensor 4, the signal processing subsequently results in obtaining a time difference between the detections of pulse wave by the first sensor 3 and the second sensor 4 in an embodiment where both sensors 3, 4 are embodied as mechanical sensors. In an exemplary embodiment, where the electrocardiograph is used as the first sensor 3, the time parameter describing the time relationship between the mechanical parameter of the aorta monitored by the first sensor 3 and the mechanical excitation of the aorta monitored by the second sensor 4 is the time difference between the detection of the R wave in the QRS complex of the electrocardiogram and the detection of the pulse wave by the second sensor 4. The time differences obtained in this way would have a virtually constant value throughout the entire measurement period in case of absolute rest of the patient. Patient movement may affect the values obtained, however, this irregularity can be detected and can be handled and eliminated by the computing unit 5.

The organs of the gastrointestinal tract lie close to the aorta. The GIT organs perform constant peristaltic and other movements. Due to their movement and change in shape, they exert a force on the aorta, compressing it or, on the contrary, relieving the pressure on it. Similarly, the fetus in utero performs its own movements, by which it compresses other organs in the woman’s body, or it can affect the aorta itself, similar to the peristaltic movements of the GIT organs. Thus, the fetus in utero can compress the aorta in various ways or, on the contrary, relieve the pressure on it. These forces affect the hemodynamics of the blood flowing through the aorta and thus delay or accelerate the pulse waveform of the aorta and the pulse is recorded by the second sensor 4 with a delay. Delays caused by peristaltic movements of the organs or movement of the fetus will affect the recorded pulse waveform of the aorta or pulse detection time. If GIT organs do not perform peristaltic movements or the fetus is not moving in utero at that moment, the time difference of the pulse wave detection by the first sensor 3 and the second sensor 4 acquires the first value. In case of peristaltic movement of the GIT or movement of the fetus, the time difference of the pulse wave detection by the first sensor 3 and the second sensor 4 acquires a second value different from the first value.

In an exemplary embodiment, detection of peristaltic movements of the GIT organs or movement of the fetus in utero is performed as follows. The second sensor 4 is placed on the male patient 2 or female patient 2 in the region behind the abdominal bifurcation in the direction of blood flow in the artery from the heart towards the legs. If the first sensor 3 is embodied as a mechanical sensor, it is placed in the upper half of the body, for example on the hand or arm. In an alternative embodiment, the first sensor 3 is embodied as an ECG. Subsequently, the pulse waveform of the aorta is measured or the time of the pulse detection, so-called pulse arrival time, is measured. The signal from the first and second sensors 3, 4 is processed by the computing unit 5 for at least 30 seconds. The upper value of the measurement time is practically unlimited and can be chosen with regard to the male or female patient’s comfort, time possibilities, and practical purpose, or it can be monitored permanently. For example, the upper value of the measurement by the first and second sensors 3, 4 is 1800 s. The computing unit 5 determines a series of values of differences of the pulse detection by the first sensor 3 and the second sensor 4. The male patient 2 or female patient 2 is at rest and lying down throughout the measurement. If the movement performed by the GIT organs or the fetus in utero is minimal or has almost no value, the time difference of pulse detections by the first sensor 3 and the second sensor 4 acquires first values, the set of first values is the same with respect to the measurement statistics, the mean value, and the standard deviation. When the GIT organs or the fetus in utero begin to make movements, these movements exert a force on the aorta. Exertion of force means in particular the compression or relaxation of the aorta. This exertion of force results in different blood flow at the compressed or relaxed site, which affects the pulse wave detection time by the second sensor 4 and the pulse waveform measured by the second sensor 4. The time difference of pulse detections by the first sensor 3 and the second sensor 4 thus acquires second values that are different from the first values. The second value denotes a set of second values that do not have to be of the same size. The value of this difference is determined by the rate of movement of the GIT organs or the fetus in utero.

From the set of computed values, the spectral density of the signal corresponding to the number of frequencies contained in this signal is determined by the computing unit 5 by the following procedure — a time series composed of a series of values of pulse detection differences in the measurement time interval is created, then the spectral density of the signal is computed from this series by determining an arbitrary frequency, for example 4 Hz. In an exemplary embodiment, the computing unit 5 is connected to a display unit 8, for example a monitor or other display, on which the obtained dependency is displayed. For example, it is shown in the form of a graph, where the X-axis shows the values of the signal frequencies, and the Y-axis shows their values over time. Fig. 5 shows this dependence obtained in an experiment on a pig in which the blood supply to the intestines was cut off during embolization, stopping peristalsis thereof. The values on the Y-axis are in minutes. Yellow vertical bars with decreasing intensity can be observed on the graph. The first bar on the left indicates the fundamental frequency, the other vertical yellow bars indicate higher harmonic components of the fundamental frequency or contain additional information. Green vertical bars indicate signal attenuation. The state before embolization, when the peristaltic movements of the intestines were performed naturally, is shown in the upper part of the figure; after embolization, when the peristaltic movements ceased, there is an observable deviation marking the interruption of the peristaltic movements at a time of about 95 min.

The assessment of cessation of the peristaltic movement of the GIT organs or movement of the fetus in utero is determined by a trained medical professional from the graphical representation shown on the display unit 8 or from a list of values. Alternatively, the computing unit 5 is adapted to detect abnormalities corresponding to the cessation of the peristaltic movement of the GIT organs or movement of the fetus in utero. The detection can be implemented by an algorithm that monitors sudden fluctuations in the spectral density of frequencies, wherein an abnormality is detected if the fluctuation in values has a longer duration to avoid detection of false fluctuations caused by e.g., sudden movement of the patient, noise, random interference with surrounding electronics, etc. The detection may also be performed using artificial intelligence, in particular neural networks with a trained classifier adapted to detect abnormalities in the measured values, where the abnormalities correspond to the cessation of the peristaltic movements of the GIT organs or movement of the fetus in utero. The detected abnormality is displayed in a list of spectral density values directly in the graphical representation for easier orientation of the medical personnel. One exemplary embodiment of the device 1 for monitoring the peristalsis of the GIT organs or movement of the fetus in utero further comprises an alert mechanism 9 which, in the event of detection of an anomaly in the measured values by the computing unit 5, alerts medical personnel that immediate medical intervention is required. The alert may be acoustic, e.g. by triggering an alarm mechanism similar to a code blue situation, by lighting up an indicator light placed on the device for monitoring the peristaltic movements of the GIT organs or movement of the fetus in utero, or the alert mechanism 9 may communicate with an internal server and send an alert to a computer, cell phone, pager, or other communication peripheral 10, thereby alerting medical personnel who may immediately provide the necessary medical care to the patient.

Using the device 1 for monitoring the movement of the fetus in utero according to the previous embodiments of the invention, it was possible to perform a series of experiments proving the practicability of the presented invention. The total of 28 patients were monitored using the device 1 for monitoring the movement of the fetus in utero for the time duration of approximately 30-60 minutes. The heart activity of the fetus was measured using the cardiotocography which produces an actogram. The movements, microvibrations, of the patient and the fetus were also simultaneously measured using a plurality of sensors 3, 4. The operational frequency of the sensors 3, 4 was set to 330 Hz. Data obtained by the sensors 3, 4 was further processed by the computing unit 5, and the first Cartan curvature was calculated. The first Cartan curvature carries information about the change of the parameters of a pulse wave reflected in the organism. Afterwards, the selected values were processed using the continuous wavelet transformation which provides information about the frequency characteristics of the given processed signal, in this case the Cartan curvature. Number of frequencies present in the results of the continuous wave transformation was then studied. Given the properties of the signal a propriate threshold value was determined for a selected interval of frequencies, in this case 0,5-1 Hz. If the average amplitude of the signal in the given interval of frequencies exceeded the threshold value, the moment was determined as a moment of a significant fetal movement. This measurement was realized with sampling frequency of 1 s. By this process, it was possible to obtain two time series. The first time series displays the timestamps of fetal movement registered by the actogram, the second time series displays the timestamps of fetal movement registered by the described algorithm of calculating the CWT from the first cartan curvature. By comparing the reference values obtained by the actogram and the measured values obtained by the sensors 3, 4, the sensitivity of the method was determined as 88%, and the specificity of the method was determined as 70%. The first time series with the movement of the fetus marked by black rectangles is depicted in the Fig. 7. The output of the CWT method applied to the first Cartan curvature of the processed signal is depicted in the Fig. 8, where the horizontal axis symbolizes time values, and the vertical axis symbolizes a magnitude of the signal. Fetal movements are easily determined from the Fig. 8.

Industrial Applicability The invention finds application in medicine, it can be used to monitor peristaltic movements of organs of the gastrointestinal tract or the fetus in utero. The device for monitoring peristalsis of the GIT organs or movement of fetus in utero forms a monitoring device that monitors the health condition of the patient.

List of Reference Numbers

1 - device for monitoring movement of fetus

2 - patient

3 - first sensor 4 - second sensor

5 - computing unit

6 - AD converter

7 - amplifier

8 - display unit 9 - alert mechanism

10 - communication peripheral

Claims

1. A device (1 ) for monitoring movement of fetus comprising a first sensor (3) adapted to be placed in the region of the upper half of the body, a second sensor (4) adapted to be placed in the region of the lower half of the body, and a computing unit (5) electrically connected to the first and second sensors (4), characterized in that the first sensor (3) is adapted to detect a mechanical parameter of the aorta, wherein the mechanical parameter is the pulse wave of the aorta, QRS complex, or R wave, and the second sensor (4) is adapted to detect a mechanical excitation of the aorta, wherein the mechanical excitation is the pulse wave of the aorta, wherein the computing unit (5) is adapted to determine the time parameter, wherein the time parameter is a time difference between the detection of the mechanical parameter of the aorta by the first sensor (3) and the detection of a mechanical excitation of the aorta by the second sensor (4), and to process the time parameter values by generating a time series of time parameter values and determining the spectral density of the time parameter values for an arbitrary signal frequency and to indicate movement of fetus by detecting deviations in the spectral density values

2. The device for monitoring movement of fetus of claim 1 , characterized in that the first sensor (3) is an electrocardiograph.

3. The device for monitoring movement of fetus of claim 1 , characterized in that the sensors (3, 4) are embodied as piezoelectric sensors or strain gauges.

4. The device for monitoring movement of fetus of any one of the preceding claims 1 to 3, characterized in that it further comprises an AD converter (6) electrically connected to the first sensor (3), the second sensor (4), and the computing unit (5).

5. The device for monitoring movement of fetus of any one of the preceding claims 1 to 4, characterized in that it further comprises a signal amplifier (7) of signal detected by the first sensor (3) and the second sensor (4).

6. The device for monitoring movement of fetus of any one of the preceding claims 1 to 5, characterized in that it further comprises an alert mechanism (9) and a communication peripheral (10) communicating with the alert mechanism (9), wherein the alert mechanism (9) is adapted to alert the medical personnel.

7. A method of monitoring movement of fetus using the device of any one of claims 1 to 6, characterized in that it comprises the following steps:

- detection of at least one mechanical parameter of the aorta by the first sensor (3), wherein the mechanical parameter is a pulse wave of the aorta, QRS complex, or R wave;

- detection of mechanical excitation of the aorta by the second sensor (4), wherein the mechanical excitation is a pulse wave of the aorta; o wherein the mechanical parameter detected by the first sensor (3) and the mechanical excitation detected by the second sensor (4) correspond to the same heartbeat;

- determination of the time parameter by the computing unit (5), wherein the time parameter is the time difference between the detection of the mechanical parameter of the aorta by the first sensor (3) and the detection of the mechanical excitation of the aorta by the second sensor (4)

- and it further comprises the steps performed by the computing unit (5): o creation of a time series of the time parameter values, o determination of the spectral density of the time parameter values for arbitrary signal frequency

- and indication of movement of fetus by detecting deviations in the spectral density values.

8. The method of monitoring movement of fetus of claim 7, characterized in that the second sensor (4) is embodied as a piezoelectric sensor or strain gauge.

9. The method of monitoring movement of fetus of any one of claims 7 and 8, characterized in that the first sensor (3) is embodied as an electrocardiograph.

10. The method of monitoring movement of fetus of any one of claims 7 and 8, characterized in that the first sensor (3) is embodied as a piezoelectric sensor or strain gauge.

11. The method of monitoring movement of fetus of any one of claims 7 to 10, characterized in that it is performed in a time range of 30-1800 s.

12. The method of monitoring movement of fetus of any one of claims 7 to 11, characterized in that the cessation of movement of fetus is indicated by the alert mechanism (9).