JP6793287B2 - Biological signal measuring device and biological signal measuring method - Google Patents

Description

The present invention relates to a biological signal measuring device or the like for measuring biological signals generated from a cardiovascular system or a respiratory system.

Conventionally, biological signals generated from the cardiovascular system and the respiratory system have been measured using dedicated measurement sensors. For example, cardiac function is measured by echocardiography, which is an expensive and labor-intensive test. In addition, the central venous pressure measurement for estimating the circulating blood volume is measured by inserting a central venous catheter, which is a highly invasive procedure. In addition, when measuring the respiratory rate and the respiratory state, there are problems that the respiratory rate measurement such as the chest wall impedance method and the capnography is unreliable, and the comfort and tolerability are low. Since highly reliable capnography requires a nasal cannula or mask, it cannot be measured if these are removed, and it is often difficult to wear the nasal cannula or mask. From the above, it is desired to measure a plurality of biological signals with high accuracy by using a single sensor which is highly comfortable and tolerable and can measure non-invasively.

Patent Document 1 discloses a biological sound acquisition terminal including a sensor support portion that supports a sound sensor and an operation unit for holding with a finger, and bands a 20 to 100 Hz component of a signal from the biological sound acquisition terminal. The pass-processed waveform is disclosed.

Japanese Unexamined Patent Publication No. 2012-090909

However, the biological sound acquisition terminal described in Patent Document 1 is not suitable for long-term monitoring because it needs to be held by the measurer. Further, regarding signal processing, only bandpass processing of 20 to 100 Hz components is described, and it is unclear whether the meaning of the bandpass processed waveform and other biological signals can be measured.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is that it can be used for long-term monitoring, is highly comfortable and tolerable, and is non-invasive. It is an object of the present invention to provide a biological signal measuring device or the like capable of measuring a plurality of biological signals with high accuracy by using the above sensors.

The first invention for achieving the above-mentioned object is to measure a signal of the living body by using a sensor attached to the body surface of the chest of the living body and provided with a piezoelectric element for converting the vibration generated by the living body into a voltage. A biological signal measuring device that inputs a first electric signal output from the piezoelectric element, amplifies the first electric signal, and amplifies the first electric signal as a first digital signal. The first digital signal is differentiated into the cardiac motion vibration signal of the living body, and the first digital signal is filtered by a band passage filter in the range of 20 to 100 Hz to obtain the living body. The first digital signal is filtered by a high-pass filter having a threshold value in the range of 100 to 400 Hz to obtain the breathing airflow sound signal of the living body, and the first digital signal has a threshold value of 0.3. The biological signal measuring device is characterized by comprising a control unit that performs signal processing to obtain the thoracic respiratory movement signal of the living body by filtering with a low frequency passing filter in the range of ~ 0.5 Hz . According to the first invention, it is possible to measure a plurality of biological signals with high accuracy by using a single non-invasive sensor that can be used for long-term monitoring, is highly comfortable and tolerated. ..

The sensor in the first invention further includes a flexible vibration transmission plate that transmits the vibration generated by the living body to the piezoelectric element, and the piezoelectric element is provided substantially at the center in the longitudinal direction of the vibration transmission plate. , The vibration transmission plate may be attached to the body surface on the thoracic bone of the living body. Since the body surface on the sternum has a substantially flat shape regardless of gender, even a plate-shaped vibration transmission plate can be reliably attached. Further, since the body surface on the sternum of the living body is a part close to the heart and the trachea, it is possible to accurately detect the vibration signal of the living body caused by heart sounds, breath sounds and the like.

The sensor in the first invention further includes a pair of electrocardiographic electrodes that detect a second electrical signal emitted by the living body, and the signal conversion unit further inputs the second electrical signal and the first. The electric signal of 2 is amplified, the second electric signal is converted into a second digital signal, and the control unit further converts the second digital signal into an electrocardiogram signal, and the electrocardiogram signal and the cardiac motion vibration. State evaluation support information that supports the functional evaluation of the living body may be generated based on at least two signals of the signal, the heart sound signal, the breathing airflow sound signal, and the thoracic respiratory movement signal. This can support the assessment of cardiovascular and respiratory conditions.

The control unit in the first invention closes and opens the mitral valve of the living body in the cardiac motion vibration signal based on the electrocardiogram signal or the heart sound signal and the heart motion vibration signal itself, and the aortic valve of the living body. The closing and opening times of the above may be specified, and the state evaluation support information related to the cardiac function evaluation of the living body may be generated based on the specified times. This can support the evaluation of cardiac contractility, cardiac diastolic function and overall cardiac function.

The control unit in the first invention specifies a reference time for each heartbeat in the cardiac motion vibration signal based on the electrocardiogram signal or the cardiac motion vibration signal itself, and a plurality of reference times based on the specified reference time. Synchronizing the cardiac motility vibration signals for heartbeats, calculating the added average of the waveforms of the cardiac motility vibration signals for a plurality of heartbeats, and relating to the evaluation of atrial fibrillation of the living body based on the calculated added averages. The state evaluation support information may be generated. This can assist in the detection of atrial fibrillation.

The control unit in the first invention may generate the state evaluation support information related to the apnea evaluation based on the breathing airflow sound signal and the thoracic respiratory movement signal. This can support the assessment of apnea.

The second invention is a biological signal measuring method for measuring a signal of the living body by using a sensor attached to the body surface of the chest of the living body and having a piezoelectric element for converting the vibration generated by the living body into a voltage. , The signal conversion unit inputs the first electric signal output from the piezoelectric element, amplifies the first electric signal, and converts the amplified first electric signal into a first digital signal. The step and the control unit differentiate the first digital signal into the cardiac motion vibration signal of the living body, and filter the first digital signal by a band passing filter in the range of 20 to 100 Hz to obtain the living body. and heart sound signal, the first threshold value digital signal is filtered by a high pass filter in the range of 100~400Hz the respiratory airflow sound signal of the living body, 0.3 a threshold said first digital signal It is a biological signal measurement method characterized by executing a step of performing signal processing to obtain the thoracic respiratory movement signal of the living body by filtering with a low frequency passing filter within the range of 0.5 Hz . The second invention makes it possible to measure a plurality of biological signals with high accuracy by using a single non-invasive sensor that can be used for long-term monitoring, is highly comfortable and tolerated. ..

According to the present invention, biological signal measurement that can be used for long-term monitoring, is highly comfortable and tolerable, and can measure a plurality of biological signals with high accuracy using a single non-invasive sensor. Equipment and the like can be provided.

The figure which shows the sensor 100 attached to the living body Perspective view of sensor 100 An exploded perspective view of the sensor 100 Cross-sectional view of the sensor 100 that passes through the center of the vibration transmission plate 11 in the width direction and is cut by a cut surface orthogonal to the width direction of the vibration transmission plate 11. Configuration diagram of biological signal measuring device 1 A flowchart showing the flow of the biological signal measurement process by the biological signal measuring device 1. Display example of signal waveforms of electrocardiogram signal, chest wall vibration signal, and cardiac motion vibration signal Display example of signal waveforms of electrocardiogram signal, chest wall vibration signal, and heartbeat signal Display example of signal waveforms of chest wall vibration signal, thoracic respiratory movement signal, and respiratory airflow sound signal Display example of signal waveforms of electrocardiogram signal, chest wall vibration signal, heart movement vibration signal, heart sound signal, respiratory airflow sound signal and thoracic respiratory movement signal The figure explaining an example of the generation processing of the state evaluation support information related to the cardiac function evaluation The figure explaining an example of the generation processing of the state evaluation support information related to the atrial fibrillation evaluation The figure explaining an example of the generation processing of the state evaluation support information related to the heartbeat evaluation

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the sensor 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4.

As shown in FIGS. 1 and 2, the sensor 100 has a disk-shaped piezoelectric element 21 that converts vibration generated by a living body into a voltage, and a width orthogonal to the longitudinal direction (= the vertical direction of the paper surface in FIG. 1) and the longitudinal direction. A flexible and insulating vibration transmission plate 11 having a direction (= the left-right direction of the paper surface in FIG. 1) and transmitting the vibration generated by the living body to the piezoelectric element 21, and both ends of the vibration transmission plate 11 in the longitudinal direction. A pair of engaging mechanisms 311 and 321 provided, a pair of electrocardiographic electrodes 31 and 32 that are engaged by a pair of engaging mechanisms 311 and 321 to detect an electric signal emitted by a living body, and a pair of both sides and a pair of piezoelectric elements 21. A film electric wire 41 for bundling a plurality of conductor patterns electrically connected to the electrocardiographic electrodes 31 and 32 of the above is provided. The piezoelectric element 21 is provided at the center of the vibration transmission plate 11 in the longitudinal direction.

As shown in FIG. 1, the sensor 100 is attached to the body surface of the chest of the living body. Desirably, the sensor 100 is attached to the body surface on the sternum of the living body. The sternum, which does not appear to be deformed by respiratory movement, is actually slightly deformed by respiratory movement. The vibration transmission plate 11 transmits the vibration generated by the deformation of the sternum to the piezoelectric element 21. In other words, the piezoelectric element 21 converts the distortion of the vibration transmission plate 11 caused by the vibration generated by the living body into a voltage.

Since the body surface on the sternum has a substantially flat shape regardless of gender, even a plate-shaped vibration transmission plate 11 can be reliably attached. Further, since the body surface on the sternum of the living body is a part close to the heart and the trachea, it is possible to accurately detect the vibration signal of the living body caused by heart sounds, breath sounds and the like. In addition, the sensor 100 attached to the body surface of the chest of the living body does not interfere with the operation performed by incising the abdomen. In addition, the sensor 100 attached to the body surface of the chest of the living body does not easily detect abdominal movements other than breathing (for example, physical skin deformation such as abdominal deformation or change of body position due to surgery) by mistake. , Does not interfere with the monitoring of respiratory function.

The size of the vibration transmission plate 11 is preferably within the size of the sternum of a living body. In the embodiment of the present invention, the vibration transmission plate 11 has a longitudinal dimension of 110 mm and the vibration transmission plate 11 has a width dimension of 30 mm. These dimensions are for general adults, and for children and newborns, it is desirable to shorten the longitudinal dimension of the vibration transmission plate 11 according to the size of the sternum. When the dimension of the vibration transmission plate 11 in the longitudinal direction is 80 mm or more, the signal detection performance of the biological body is good.

Further, as the material of the vibration transmission plate 11, an elastic plastic having an appropriate resilience is used. The thickness of the vibration transmission plate 11 is a low frequency band of 0.5 Hz or less, which is characteristic of thoracic respiratory movements, a frequency band of 20 to 100 Hz, which is characteristic of heart sounds, and a frequency band of 100 to 400 Hz, which is characteristic of breath sounds. It is necessary to have an appropriate thickness that can detect all of the frequency bands of, and 0.3 mm to 2.0 mm is desirable. In the embodiment of the present invention, the material of the vibration transmission plate 11 is a composite material of a glass epoxy plate and a vinyl chloride resin (PVC), and the thickness of the vibration transmission plate 11 is 1.0 mm.

As shown in FIGS. 3 and 4, the vibration transmission plate 11 has a substrate 111 on which the piezoelectric element 21 is placed and a coating plate 112 adhered to the substrate 111. A pair of engaging mechanisms 311, 321 and copper foil conductor patterns 151, 152, 153, 154, and 211 are formed on the substrate 111. Both sides of the piezoelectric element 21 are electrically connected to the film electric wire 41 via conductor patterns 151, 152, and 211. The pair of electrocardiographic electrodes 31 and 32 are electrically connected to the film electric wire 41 via the conductor patterns 153 and 154. The film electric wire 41 is electrically connected to the biological signal measuring device 1 described later.

The covering plate 112 is crimped to the substrate 111 with the piezoelectric element 21, the pair of engaging mechanisms 311, 321 and the conductor patterns 151, 152, 153, 154, 211 interposed therebetween. The covering plate 112 is formed with a circular hole at a position facing the pair of engaging mechanisms 311 and 321 formed on the vibration transmission plate 11.

In order for the piezoelectric element 21 to efficiently convert the vibration of the living body into an electric signal, it is desirable that the substrate 111 and the covering plate 112 are in close contact with each other without any gaps. In the embodiment of the present invention, the covering plate 112 is heated to be softened, deformed and adhered to the shape of the piezoelectric element 21, and crimped. Therefore, the material of the covering plate 112 is preferably a plastic having thermoplasticity, for example, polyethylene (PE), polypropylene (PP), vinyl chloride resin (PVC), polystyrene (PS), ABS resin (ABS), polyethylene. Teflate (PET), acrylic resin (PMMA), polycarbonate (PC) or polyamide (PA) are desirable. In the embodiment of the present invention, a vinyl chloride resin (PVC) having a thickness of 0.5 mm, which is inexpensive and has excellent workability, is used as the material of the covering plate 112. Since thermoplastics having thermoplasticity have the property of shrinking in the rolling direction at the time of manufacture when heated (above the glass transition point of the polymer molecule), the cladding plate 112 should be annealed before being heated and crimped. Is desirable.

In the embodiment of the present invention, the material of the substrate 111 is a 0.3 mm glass epoxy printed circuit board (PCB). Conductor patterns 151, 152, 153, 154, and 211 that connect the parts are formed in advance by attaching a copper foil having a thickness of 18 μm to the substrate 111 and performing an etching process. As a result, when the vibration transmission plate 11 is formed by thermocompression bonding, the piezoelectric element 21 and the pair of engaging mechanisms 311, 321 mounted on the substrate 111 and the conductor patterns 151, 152, 153, 154, 211 Due to the difference in the coefficient of thermal expansion of each component, the connection portion can minimize the occurrence of defects such as tearing due to local stress concentration in the heating-cooling process.

In the embodiment of the present invention, a hot melt sheet 103 having a thickness of 50 μm is used as an adhesive in thermocompression bonding of the substrate 111 and the covering plate 112. The material of the hot melt sheet 103 is preferably a polyester type which is in a molten state at about 80 ° C. or higher and has high adhesiveness and flexibility. By heating at a temperature of 90 to 120 ° C. for 1 to 3 minutes at the time of thermocompression bonding, it is possible to reliably crimp without peeling in the normal range of use. Due to the difference in the coefficient of thermal expansion between the substrate 111 and the covering plate 112, warpage occurs in the cooling process, but by cooling and molding in a state that is slightly opposite to the warping direction, the vibration transmission plate 11 is cooled. Can be made into a flat shape.

On the surface of the electrocardiographic electrodes 31 and 32 facing the body surface, as an adhesive for attaching the biosensor 100 to the body surface, a stable silver-silver chloride electrode having a low polarization voltage and high conductivity with high adhesion Adhesive gels 315 and 325 are applied to transmit a weak electromotive voltage of the myocardium from the body surface. By directly attaching the surfaces of the electrocardiographic electrodes 31 and 32 to which the conductive adhesive gels 315 and 325 are applied to the epidermis directly above the sternum of the chest of the living body, the electrocardiographic waveform and the vibration waveform of the living body surface can be obtained by a single biosensor. 100 makes it possible to detect at the same time. The pressure-sensitive adhesive is not limited to the conductive pressure-sensitive adhesive gels 315 and 325, and may be a conductive pressure-sensitive adhesive seal.

Each of the pair of engaging mechanisms 311 and 321 has an insertion port in which a circular hole is formed in the center of a donut-shaped metal plate, and a plurality of slits are formed radially in the hole. Cylindrical protrusions 313 and 323 are formed on the surfaces of the electrocardiographic electrodes 31 and 32 facing the substrate 111. Grooves that go around the side surface are formed in the protrusions 313 and 323. By inserting the protrusions 313 and 323 of the electrocardiographic electrodes 31 and 32 into the insertion ports of the engaging mechanisms 311, 321 respectively, the electrocardiographic electrodes 31 and 32 are locked to the engaging mechanisms 311, 321. The insertion ports of the engaging mechanisms 311 and 321 become leaf springs through slits and fit into the grooves of the protrusions 313 and 323. Therefore, the protrusions 313 and 323 of the electrocardiographic electrodes 31 and 32 are securely locked without shifting the engaging portion in normal use, so that the electrocardiogram signals of the electrocardiographic electrodes 31 and 32 are conducted without poor contact. At the same time, the vibration of the body surface is transmitted to the piezoelectric element 21 via the vibration transmission plate 11.

Although the electrocardiographic pads 314 and 324 of the electrocardiographic electrodes 31 and 32 are in contact with the body surface S by the adhesive conductive adhesive gels 315 and 325, the vibration of the body surface S causes the conductive adhesive gels 315 and 325. There is some attenuation through. However, in the embodiment of the present invention, since it has a high signal / noise ratio (= S / N ratio) in the frequency range "0.1 to 1 kHz" required for detecting various biological signals described later, It is possible to detect biological signals with high accuracy.

Next, the biological signal measuring device 1 according to the embodiment of the present invention will be described with reference to FIGS. 5 to 14. The biological signal measuring device 1 measures the signal of the living body by using the sensor 100 attached to the body surface of the chest of the living body (preferably, the body surface on the sternum of the living body).

As shown in FIG. 5, the biometric signal measuring device 1 inputs a signal conversion unit 2 that converts a biometric signal output from the sensor 100 into a digital signal and a digital signal converted by the signal conversion unit 2, and performs signal processing. A control unit 3 for storing the digital signal converted by the signal conversion unit 2 and a storage unit 4 for storing the result of signal processing by the control unit 3, a display unit 5 for displaying the result of signal processing by the control unit 3. A communication unit 6 for transmitting the result of signal processing by the control unit 3 to the outside is provided.

The signal conversion unit 2 includes an amplifier and an AD converter. The control unit 3 is composed of, for example, a DSP (Digital Signal Processor) which is a processor dedicated to signal processing, and a CPU (Central Processing Unit) which executes processing other than signal processing and controls each unit.

The storage unit 4 is a flash memory, an HDD (Hard Disk Drive), or the like, and stores programs and data for executing processing by the control unit 3 in advance. The display unit 5 is a liquid crystal display or the like. The communication unit 6 exchanges data with other computers via a wireless LAN (Local Area Network), a wired LAN, Bluetooth (registered trademark) communication, the Internet, or the like.

FIG. 6 shows the flow of the biological signal measurement process by the biological signal measuring device 1. Steps S2 to S4 in FIG. 6 may be executed at the time of measurement. Further, at the time of measurement, only the processing result of step S1 may be stored in the storage unit 4, and steps S2 to S4 may be executed after the measurement. In the following, all steps will be described as being performed at the time of measurement in order to monitor changes in the state of the living body in real time.

The signal conversion unit 2 inputs an electric signal from the sensor 100 and converts it into a digital signal (step S1). The signal conversion unit 2 inputs a first electric signal which is an analog signal output from the piezoelectric element 21, amplifies the first electric signal, and abundates the amplified first electric signal at predetermined sampling intervals. Convert to a digital signal of 1. Further, the signal conversion unit 2 inputs a second electric signal which is an analog signal detected by the pair of electrocardiographic electrodes 31 and 32 at a predetermined sampling interval, amplifies the second electric signal, and performs a second. Converts an electrical signal into a second digital signal.

The control unit 3 inputs a digital signal from the signal conversion unit 2, executes signal processing (step S2), and displays the processed signal waveform on the display unit 5 (step S3).

The control unit 3 differentiates the first digital signal into a biological cardiac motion vibration signal, filters the first digital signal with a band passage filter to obtain a biological heart sound signal, and passes the first digital signal in a high frequency range. Signal processing is performed to filter by a filter to obtain a breathing airflow sound signal of a living body, and to filter a first digital signal by a low-pass filter to obtain a thoracic respiratory movement signal of a living body. Further, the control unit 3 uses the second digital signal as an electrocardiogram signal.

FIG. 7 shows a display example of each signal waveform of the electrocardiogram signal, the chest wall vibration signal, and the cardiac motion vibration signal. The electrocardiogram signal is a second digital signal obtained by converting a second electric signal which is an analog signal detected by a pair of electrocardiographic electrodes 31 and 32. The chest wall vibration signal is a first digital signal obtained by converting a first electric signal which is an analog signal output from the piezoelectric element 21. The cardiac motion vibration signal is a derivative of the first digital signal, that is, the chest wall vibration signal.

The waveform of the cardiac motion vibration signal is a characteristic signal waveform, and the amplitude and interval of the waveform change depending on the pathological condition. As shown in FIG. 7, the cardiac motion vibration includes atrial-related vibration and ventricular-related vibration. The signal waveform related to the ventricular-related vibration reflects the closure and opening of the mitral valve of the living body and the closing and opening of the aortic valve of the living body. MC indicates the time of mitral valve closure, AO indicates the time of aortic valve opening, MO indicates the time of mitral valve opening, and AC indicates the time of aortic valve closure.

FIG. 8 shows a display example of each signal waveform of the electrocardiogram signal, the chest wall vibration signal, and the heartbeat signal. The heartbeat signal is a chest wall vibration signal filtered by a bandpass filter. The bandpass filter is preferably in the range of 20 to 100 Hz. In the embodiment of the present invention, the lower limit threshold value is 20 Hz and the upper limit threshold value is 45 Hz.

FIG. 9 shows a display example of each signal waveform of the chest wall vibration signal, the thoracic respiratory movement signal, and the respiratory airflow sound signal. The thoracic respiratory movement signal is a filter of the chest wall vibration signal by a low-pass filter. The threshold value of the low-pass filter is preferably in the range of 0.3 to 0.5 Hz. In the embodiment of the present invention, the threshold value of the low-pass filter is 0.4 Hz. In order to cut noise, the control unit 3 may pass a frequency of 0.05 Hz or higher. In this case, the control unit 3 performs the same process as filtering the chest wall vibration signal with a bandpass filter of 0.05 Hz to 0.4 Hz.

The respiratory airflow sound signal is a chest wall vibration signal filtered by a high-pass filter. The threshold value of the high frequency pass filter is preferably in the range of 100 to 400 Hz. In the embodiment of the present invention, the threshold value of the high frequency pass filter is set to any of 200 Hz, 300 Hz, and 400 Hz.

FIG. 10 shows a display example of signal waveforms of an electrocardiogram signal, a chest wall vibration signal, a heart movement vibration signal, a heart sound signal, a respiratory airflow sound signal, and a thoracic respiratory movement signal. As described above, the electrocardiogram signal and the chest wall vibration signal are obtained by performing signal processing on digital signals simultaneously obtained from a single sensor 100. Further, the cardiac motion vibration signal, the cardiac sound signal, the respiratory airflow sound signal and the thoracic respiratory motion signal are obtained by performing signal processing on the chest wall vibration signal. Therefore, the biological signal measuring device 1 can measure all these signals at the same time by using a single sensor 100.

Returning to the description of FIG. Based on the result of the signal processing in step S2, the control unit 3 generates state evaluation support information which is information for supporting the state evaluation of the living body, particularly the state evaluation of the cardiovascular system and the respiratory system (step S4).

The control unit 3 generates state evaluation support information based on at least two signals of an electrocardiogram signal, a cardiac motion vibration signal, a cardiac sound signal, a respiratory airflow sound signal, and a thoracic respiratory motion signal. Details of the status evaluation support information will be described later.

The control unit 3 determines whether or not the state of the living body is abnormal based on the state evaluation support information (step S5). When the state of the living body is abnormal (Yes in step S5), the control unit 3 outputs a warning to the display unit 5 (step S6), and stores the processing results of steps S2 to S4 and S6 as time-series data in the storage unit 4. It is memorized and repeated from step S1. When the state of the living body is normal (No in step S5), the control unit 3 stores the processing results of steps S2 to S4 in the storage unit 4 as time-series data, and repeats from step S1.

Hereinafter, the process of generating the state evaluation support information will be described in detail with reference to FIGS. 11 to 13.

<Evaluation of cardiac function>
In the embodiment of the present invention, the cardiac motion vibration signal can be obtained from the battlement vibration signal (see FIG. 7). The amplitude of the waveform of the cardiac motion vibration signal is proportional to the cardiac contractility. Therefore, it is possible to continuously measure the cardiac motion vibration signal and monitor the transition of cardiac function by the trend of the amplitude of the cardiac motion vibration signal waveform. In addition, since the interval between the waveforms of the cardiac motion vibration signal is extended in the pathological condition in which the cardiac function is deteriorated such as heart failure, the cardiac function can be evaluated based on the interval between the waveforms of the cardiac motion vibration signal.

An example of the state evaluation support information related to the cardiac function evaluation will be described with reference to FIG. The value of (aortic valve opening time AO-mitral valve closing time MC) / (aortic valve closing time AC-aortic valve opening time AO) is an index of cardiac contractility. The values of (mitral valve opening time MO-aortic valve closing time AC) / (aortic valve closing time AC-aortic valve opening time AO) are indicators of cardiac dilatation ability. Then, as shown in FIG. 11, the sum of these is {(aortic valve opening time AO-mitral valve closing time MC) + (mitral valve opening time MO-aortic valve closing time AC)} / (aortic valve closing time). The value of AC-aortic valve opening time AO) is an index of comprehensive cardiac function, and a value of 0.45 or more is judged to be a decrease in cardiac function.

The mitral valve closing time MC, the aortic valve opening time AO, the aortic valve closing time AC, and the mitral valve opening time MO can be determined from the waveforms of the cardiac motion vibration signals. The aortic valve opening time AO is the time at which the largest of the upwardly convex peaks observed after the ECG QRS complex or in the vicinity of the heart sound I is taken. The mitral valve closure time MC is usually the start time of a sharp descending wave after the appearance of the ECG QRS complex or near the heart sound I sound, just before the aortic valve opening time AO, but sometimes as shown in FIG. It may have a convex peak on the top. The mitral valve opening time MO is a time at which a downwardly convex peak is taken after the electrocardiogram T wave or near the heart sound II sound. The aortic valve closure time AC is the time after the electrocardiogram T wave or immediately before the peak of the heart sound II sound, which comes before the peak related to the mitral valve opening time MO and takes an upwardly convex peak.

Based on these findings, the control unit 3 closes and opens the mitral valve of the living body and closes and opens the aortic valve of the living body in the heart movement vibration signal based on the electrocardiogram signal or the heartbeat signal and the heart movement vibration signal itself. Each time is specified, and state evaluation support information related to the evaluation of the cardiac function of the living body is generated based on each specified time. Examples of the state evaluation support information include the values of the above-mentioned index of cardiac contractility, index of cardiac diastolic ability, and index of comprehensive cardiac function. This can support the evaluation of cardiac contractility, cardiac diastolic function and overall cardiac function.

Cardiac function can be evaluated by measuring the waveform interval of the cardiac motion vibration signal as an absolute value even by a single measurement of the cardiac motion vibration signal, but continuous measurement of the cardiac motion vibration signal is performed and the waveform interval of the cardiac motion vibration signal is performed. By comparing the context of the above, the transition of cardiac function can be monitored over time.

Since the amplitude and interval of the waveform of the cardiac motion vibration signal change even in cardiac hypertrophy, which is a pre-pathological condition of heart failure, cardiac hypertrophy was discovered by measuring the amplitude and interval of the waveform of the cardiac motor vibration signal, and evaluated multiple times over time. By doing so, the progression of the pathological condition can be evaluated. The battlemental vibration signal is continuously measurable and non-invasive.

<Evaluation of circulating blood volume>
In the embodiment of the present invention, since the cardiac motion vibration signal can be measured, the excess or deficiency of the circulating blood volume can be non-invasively estimated from the respiratory fluctuation of the waveform interval of the cardiac motion vibration signal and the infusion reactivity.

<Atrial fibrillation evaluation>
Atrial fibrillation is an arrhythmia that can lead to heart failure, but it is also a very important primary disease of cerebral infarction and is conventionally diagnosed by electrocardiogram. In the embodiment of the present invention, the atrium-related vibration signal can be obtained from the cardiac motion vibration signal (see FIG. 7).

An example of the state evaluation support information related to the atrial fibrillation evaluation will be described with reference to FIG. As shown in FIG. 12, in a normal rhythm called sinus rhythm, myocardial contraction occurs at an almost constant rhythm following atrial contraction. Therefore, in the cardiac motor vibration signal, a series of ventricular-related vibration signals following the atrial-related vibration signal. A signal waveform can be seen (see FIG. 7). On the other hand, in atrial fibrillation, although a ventricular-related vibration signal is generated, a constant atrial-related vibration does not occur before that and is irregular. When the cardiac motion vibration signals of about 10 heartbeats or more are added and averaged, the ventricle-related vibration signal is generated. Immediately before is a flat waveform.
The reference time for synchronizing the plurality of heartbeats can be a time that can be determined based on the electrocardiogram signal, for example, the time when the peak of the QRS complex is taken. In addition, the time can be determined based on the time at which the peak of the cardiac motion vibration signal itself is taken, which makes it possible to detect atrial fibrillation without necessarily using an electrocardiogram.

Based on these findings, the control unit 3 identifies the reference time of each heartbeat in the cardiac motion vibration signal based on the electrocardiogram signal or the cardiac motion vibration signal itself, and the control unit 3 determines the reference time of each heartbeat based on the specified reference time for a plurality of heartbeats. Synchronize the cardiac motion vibration signals, calculate the added average of the waveforms of the cardiac motion vibration signals for multiple heartbeats, and generate the state evaluation support information related to the evaluation of atrial fibrillation of the living body based on the calculated added average. .. Examples of the state evaluation support information include the waveform of the averaging and the determination result of the presence or absence of atrial-related vibration. This can assist in the detection of atrial fibrillation.

<Heart sound evaluation>
In the embodiment of the present invention, a heartbeat signal can be obtained from the battlement vibration signal (see FIG. 8). As for the heart sounds, abnormalities of the I and II sounds reflect the heart valve disease, and the appearance of the abnormal heart sounds III and IV, which may occur after the II sound, suggests the possibility of heart diseases such as heart failure. In the present invention, not only the I sound and the II sound but also the III sound and the IV sound can be identified (see FIG. 13).
For example, the control unit 3 identifies the I sound and the II sound with reference to the QRS wave of the electrocardiogram signal, and generates the III sound or the IV sound depending on whether the amplitude of the heart sound signal after the II sound is equal to or more than a predetermined threshold. Identify the presence or absence.

<Respiratory rate and respiratory status evaluation>
In the embodiment of the present invention, the inspiratory sound, the expiratory sound, and the time zone of the airflow stop occurring between the two (= inspiratory / expiratory transition pose in FIG. 9) can be detected, and the thoracic respiratory movement signal can be detected. Can measure numbers and respiratory status.

In the embodiment of the present invention, the respiratory airflow sound signal and the thoracic respiratory movement signal can be simultaneously extracted from the chest wall vibration signal (see FIG. 9). By obtaining the biological signals related to these two respirations at the same time and in completely different frequency bands, even if noise specific to one of the biological signals related to the two respirations is generated and the signal cannot be obtained. One signal can maintain accurate respiratory rate measurements. That is, the resistance to noise is increased. In addition, even when noise is generated over the entire signal band, since the respiratory airflow sound signal is a relatively high frequency band as a biological signal, the biological signal can be obtained immediately before or after the noise, and the thoracic respiratory movement signal can be obtained. Together with this, it can support the estimation of the respiratory rate and the respiratory condition with high accuracy.

Based on these findings, the control unit 3 measures the respiratory rate of the living body based on the respiratory airflow sound signal, and also measures the respiratory rate of the living body based on the thoracic respiratory movement signal, and is a state related to the respiratory rate evaluation of the living body. Generate evaluation support information.
For example, the control unit 3 identifies the time zone in which the inspiratory sound and the expiratory sound are generated based on the magnitude of the amplitude of the respiratory airflow sound signal, and counts a set of the inspiratory sound and the expiratory sound as one breath. To do. Further, for example, the control unit 3 extracts the peak of the thoracic respiratory movement signal, and counts the downwardly convex peak and the upwardly convex peak as one breath. Examples of the state evaluation support information include a respiratory rate estimated based on the respiratory airflow sound signal, a respiratory rate estimated based on the thoracic respiratory movement signal, and the like.

<Apnea evaluation>
Apnea is divided into central apnea, which is an abnormality of the respiratory center, and obstructive apnea, which is an abnormality of the airways. In the embodiment of the present invention, the respiratory airflow sound signal and the thoracic respiratory movement signal can be obtained at the same time (see FIG. 9). Apnea can be diagnosed if no respiratory airflow sound signal is observed. Moreover, central apnea can be diagnosed without a thoracic respiratory movement signal, and obstructive apnea with a thoracic respiratory movement signal. In addition, the number and duration of apnea events can be measured by counting the respiratory airflow sound signal and the thoracic respiratory movement signal.

Based on these findings, the control unit 3 generates state evaluation support information related to apnea evaluation based on the respiratory airflow sound signal and the thoracic respiratory movement signal.
For example, the control unit 3 specifies a time zone in which the inspiratory sound and the expiratory sound are generated based on the magnitude of the amplitude of the respiratory airflow sound signal, and sets the set of the inspiratory sound and the expiratory sound as one breath. If the interval between breaths is equal to or greater than the threshold, it is judged that apnea has occurred. Further, for example, the control unit 3 extracts the peak of the thoracic respiratory movement signal, sets the downward convex peak and the upward convex peak as one breath, and the occurrence interval between breaths is equal to or more than the threshold value. If so, it is judged that apnea has occurred. The state evaluation support information includes the identification result of whether the apnea event is central apnea or obstructive apnea, the number and time of the apnea event, and the like. This can support the assessment of apnea.

<Respiratory disease evaluation>
Prolonged egressive sound is observed in bronchial asthma and chronic obstructive pulmonary disease. In addition, when bronchial asthma becomes severe, respiratory sounds are markedly reduced and respiratory rate is increased. In the embodiment of the present invention, the expiratory airflow sound signal can be quantitatively detected, which contributes to these diagnoses and pathological condition management.

<Tracheal intubation evaluation>
In tracheal intubation, if the trachea is properly intubated and ventilated, respiratory airflow is generated in the trachea and the thorax is elevated. On the other hand, esophageal intubation may occur in which a tube is accidentally inserted into the esophagus adjacent to the trachea when tracheal intubation is performed. Since esophageal intubation is not a physiologically patented space in the esophagus, no respiratory airflow is generated and the thorax does not rise even if artificial respiration is performed. In the embodiment of the present invention, since the respiratory airflow sound signal in the trachea and the thoracic respiratory movement signal can be obtained at the same time, the patient is intubated into the trachea by simultaneously detecting the respiratory airflow sound in the trachea and the elevation of the thorax during tracheal intubation. , It can be confirmed that ventilation is possible.

As described above, according to the biological signal measuring device 1, a plurality of highly accurate sensors 100 that can be used for long-term monitoring, are highly comfortable and tolerable, and are non-invasive are used. It is possible to measure the biological signal of. Further, according to the biological signal measuring device 1, it is possible to support the evaluation of the state of the cardiovascular system and the respiratory system.

Although preferred embodiments of the biological signal measuring device and the like according to the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified examples or modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.

1 ......... Biological signal measuring device 2 ......... Signal conversion unit 3 ......... Control unit 100 ......... Sensor 11 ......... Vibration transmission plate 21 ......... Piezoelectric elements 31, 32 ......... A pair of electrocardiographic electrodes

Claims (7)

A biological signal measuring device that measures a signal of a living body by using a sensor attached to the body surface of the chest of the living body and having a piezoelectric element that converts the vibration generated by the living body into a voltage.
A signal conversion unit that inputs a first electric signal output from the piezoelectric element, amplifies the first electric signal, and converts the amplified first electric signal into a first digital signal.
The first digital signal is differentiated into the cardiac motion vibration signal of the living body, and the first digital signal is filtered by a band passing filter in the range of 20 to 100 Hz to obtain the heart sound signal of the living body. The digital signal is filtered by a high-pass filter having a threshold value in the range of 100 to 400 Hz to obtain the breathing airflow sound signal of the living body, and the first digital signal is filtered by a high frequency passing filter having a threshold value in the range of 0.3 to 0.5 Hz. A biological signal measuring device comprising a control unit that performs signal processing to obtain a thoracic respiratory movement signal of the living body by filtering with a low frequency passing filter. The sensor further includes a flexible vibration transmission plate that transmits the vibration generated by the living body to the piezoelectric element.
The piezoelectric element is provided substantially in the center of the vibration transmission plate in the longitudinal direction.
The biological signal measuring device according to claim 1, wherein the vibration transmission plate is attached to a body surface on the sternum of the living body. The sensor further comprises a pair of electrocardiographic electrodes that detect a second electrical signal emitted by the living body.
The signal conversion unit further inputs the second electric signal, amplifies the second electric signal, converts the second electric signal into a second digital signal, and then converts the second electric signal into a second digital signal.
The control unit further uses the second digital signal as an electrocardiogram signal, and converts it into at least two of the electrocardiogram signal, the cardiac motion vibration signal, the cardiac sound signal, the respiratory airflow sound signal, and the thoracic respiratory motion signal. The biological signal measuring device according to claim 1 or 2, wherein the state evaluation support information that supports the functional evaluation of the living body is generated based on the above. The control unit closes and opens the mitral valve of the living body and closes and opens the aortic valve of the living body in the heart movement vibration signal based on the electrocardiogram signal or the heart sound signal and the heart movement vibration signal itself. The biological signal measuring apparatus according to claim 3, wherein each time is specified and the state evaluation support information related to the evaluation of the cardiac function of the living body is generated based on each specified time. The control unit specifies a reference time for each heartbeat in the cardiac motion vibration signal based on the electrocardiogram signal or the cardiac motion vibration signal itself, and the hearts for a plurality of heartbeats based on the specified reference time. The state evaluation support information related to the atrial fibrillation evaluation of the living body is calculated based on the calculated added average of the waveforms of the cardiac motion vibration signals for a plurality of heartbeats by synchronizing the exercise vibration signals. The biological signal measuring apparatus according to claim 3, wherein the biological signal measuring apparatus is generated. The biological signal measuring device according to claim 3, wherein the control unit generates the state evaluation support information related to the apnea evaluation based on the breathing airflow sound signal and the thoracic respiratory movement signal. A biological signal measuring method for measuring a signal of a living body by using a sensor attached to the body surface of the chest of the living body and equipped with a piezoelectric element for converting the vibration generated by the living body into a voltage.
A step in which a signal conversion unit inputs a first electric signal output from the piezoelectric element, amplifies the first electric signal, and converts the amplified first electric signal into a first digital signal. When,
The control unit differentiates the first digital signal into the cardiac motion vibration signal of the living body, and filters the first digital signal by a band passage filter in the range of 20 to 100 Hz to obtain the heart sound signal of the living body. The first digital signal is filtered by a high frequency passing filter having a threshold value in the range of 100 to 400 Hz to obtain a breathing airflow sound signal of the living body, and the first digital signal has a threshold value of 0.3 to 0.5 Hz. A method for measuring a biological signal, which comprises performing a signal processing step of filtering by a low-pass filter within the range of the above to obtain a thoracic respiratory movement signal of the living body.