JP6566513B2 - Estimator for cardiac volume and cardiac output - Google Patents

Description

  The present invention relates to a heart volume and cardiac output estimation device capable of detecting changes in cardiac volume and cardiac output in a non-contact and non-constrained manner.

  Conventionally, stroke volume and cardiac output have been measured in order to confirm heart failure diagnosis, prognostic treatment effect or medication effect. As a specific measurement method, there is an open type represented by a Fick method, a dye dilution method, a thermodilution method using a Swanganz catheter, and the like. Non-invasive measurement methods have been proposed for diagnosis using the Cuvicek's four-electrode method or ultrasonic echo.

  However, these measurement methods are not used at present because of problems such as the need to restrain the person to be measured and insufficient accuracy.

  On the other hand, the present inventor has discovered that the microwave transmitted through the heart changes in amplitude and phase in accordance with the movement of the contraction and expansion of the heart, and based on such discovery, the microwave transmitted through the heart. A heartbeat detection device capable of obtaining a heartbeat by analyzing the above has been proposed (see Patent Document 1).

  According to the heartbeat detection device according to Patent Document 1, the heartbeat of the measurement subject can be obtained in a non-contact and non-constrained manner. However, although the heart rate can be obtained, it has not been studied to obtain the stroke volume and the cardiac output and their time series changes.

  In addition, for the purpose of diagnosing heart failure or the like, changes in the volume of the heart (hereinafter referred to as heart volume) are also measured, but no non-contact and non-restraining methods have been proposed.

JP 2013-153783 A

  In view of such circumstances, the present invention provides an estimation device for cardiac volume and cardiac output that can detect time-series changes in the cardiac volume and cardiac output of a measurement subject without contact and without restraint. The purpose is to do.

A first aspect for achieving the above object includes: a radio wave transmission unit that radiates radio waves toward the heart of the measurement subject; a radio wave reception unit that receives radio waves that have passed through the heart of the measurement subject; Detection means for detecting a detection signal by detecting a radio wave transmitted through the heart received by the reception means, and a cardiac volume based on a change in amplitude or phase of the detection signal caused by the radio wave passing through the heart and attenuated And an estimation means for estimating a change in cardiac output , wherein the radio wave transmission means and the radio wave reception means are disposed to face each other so that radio waves can pass through the heart. It is in an estimation device for cardiac volume and cardiac output.

According to a second aspect of the present invention, in the heart volume and cardiac output estimation device described in the first aspect, the estimation means sets the intensity of the radio wave transmitted by the radio wave transmission means to E0, and the detection The intensity of the signal is E, the attenuation constant of the radio wave transmitted through the heart is α, the heart volume is V, and the time series change of the heart volume V estimated by the following Equation 1 is estimated as the change of the heart volume. It is in the estimation device of the characteristic heart volume and cardiac output.

  In the second mode, assuming that the shape of the heart is a sphere, the change in the heart volume can be estimated by using the above formula.

  According to a third aspect of the present invention, in the heart volume and cardiac output estimation device according to the first aspect, the estimation means includes a range including a maximum value and a minimum value within a predetermined period of the detection signal. Is a heart rate signal corresponding to one heartbeat, and the time-series change of the maximum value is estimated as a change in stroke volume.

  According to a fourth aspect of the present invention, in the heart volume and cardiac output estimating device described in the third aspect, the maximum values of the heartbeat signals for a predetermined period are integrated to obtain a cardiac output estimated value, A time volume change of the estimated cardiac output value is estimated as a change in cardiac output.

  According to a fifth aspect of the present invention, in the heart volume and cardiac output estimation device according to the first aspect, the estimation means includes a range including a maximum value and a minimum value within a predetermined period of the detection signal. Is a heartbeat signal corresponding to one heartbeat, and a time-series change of the difference value between the maximum value and the minimum value is estimated as a change in stroke volume, and the cardiac volume and cardiac output In the quantity estimation device.

  According to a sixth aspect of the present invention, in the cardiac volume and cardiac output estimating device described in the fifth aspect, the difference values of the heartbeat signals for a predetermined period are integrated to obtain a cardiac output estimated value, A time volume change of the estimated cardiac output value is estimated as a change in cardiac output.

  According to a seventh aspect of the present invention, in the heart volume and cardiac output estimation device according to any one of the first to sixth aspects, the radio wave transmitting means irradiates vertically polarized waves toward the heart. The radio wave receiving means is arranged to receive vertically polarized waves transmitted through the right ventricle and right atrium or the left ventricle and left atrium of the heart, and estimates the cardiac volume and cardiac output. In the device.

  According to an eighth aspect of the present invention, in the heart volume and cardiac output estimation device according to any one of the first to sixth aspects, the radio wave transmitting means irradiates a horizontally polarized wave toward the heart. The radio wave receiving means is arranged to receive horizontally polarized waves transmitted through the right ventricle and the left ventricle or the right atrium and the left atrium of the heart, and estimates the cardiac volume and cardiac output. In the device.

  According to a ninth aspect of the present invention, in the heart volume and cardiac output estimation device according to any one of the first to eighth aspects, the device includes a cylindrical member that is worn around the chest of a human body, In the apparatus for estimating cardiac volume and cardiac output, the cylindrical member is attached so that the radio wave transmitting means and the radio wave receiving means are opposed to each other.

  According to a tenth aspect of the present invention, in the heart volume and cardiac output estimation device according to any one of the first to eighth aspects, a bedding is provided, and the radio wave transmission is performed on a floor surface side of the bedding. One of the means and the radio wave receiving means is disposed, and the other of the radio wave transmitting means and the radio wave receiving means is disposed above the bedding.

  ADVANTAGE OF THE INVENTION According to this invention, the estimation apparatus of the cardiac volume and cardiac output which can detect the time-sequential change of a measurement subject's cardiac volume and cardiac output without contact and non-restraint is provided.

It is the schematic which shows the external appearance of the estimation apparatus which concerns on Embodiment 1. FIG. It is the figure which showed the function of the estimation apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the microwave before and behind permeate | transmitting a human body. It is a figure showing the relationship between the electric field strength of the microwave which permeate | transmits the heart, and the magnitude | size of the heart. It is an example of the detection signal obtained by detecting the microwave which permeate | transmitted the heart. It is the schematic of the estimation apparatus which concerns on Embodiment 3. FIG. It is the schematic of the estimation apparatus which concerns on Embodiment 4. FIG.

<Embodiment 1>
A heart volume and cardiac output estimation device (hereinafter also simply referred to as an estimation device) according to the present embodiment will be described. The estimation device is a device that estimates changes in the heart volume and cardiac output of the measurement subject using radio waves (microwaves). Although the measurement subject can be applied to animals other than humans, in this embodiment, the measurement subject is described as a human heart.

[Device configuration]
FIG. 1 is a schematic diagram illustrating an appearance of an estimation apparatus according to the present embodiment, and FIG. 2 is a diagram illustrating functions of the estimation apparatus according to the present embodiment.

  The estimation apparatus 10 includes an estimation unit 11 as an estimation unit, a transmission unit 12 and a transmission antenna 13 as radio wave transmission units, a reception unit 15 and a reception antenna 14 as radio wave reception units, a detection unit 16 as a detection unit, and a sampling unit 17. And.

  The transmitter 12 is a device for transmitting a high frequency, preferably a continuous microwave, to the human body 1. Any frequency band may be used as long as the microwave can be received through the body of the human body 1. In the present embodiment, for example, a frequency around 1 GHz including a sub-giga band is used. The transmission output may be such that sufficient power can be detected on the receiving side. In this embodiment, it is set to several m to several tens mW. The transmission unit 12 supplies a high-frequency signal generated by a microwave oscillator (not shown) to the transmission antenna 13.

  The transmission antenna 13 is a device that irradiates the microwave transmitted by the transmission unit 12 toward the heart of the human body 1. The reception antenna 14 is a device for receiving the microwave radiated from the transmission antenna 13. Specifically, the transmission antenna 13 and the reception antenna 14 are omnidirectional dipole antennas. The transmitting antenna 13 and the receiving antenna 14 are placed facing each other so that the microwaves pass through the heart 2 of the human body 1, and are held at an optimal interval for acquiring a signal. For polarization, either horizontal polarization or vertical polarization may be used.

  In the present embodiment, the transmission antenna 13 is installed on the front surface of the human body 1 and the reception antenna 14 is installed on the rear surface of the human body 1. Moreover, although the dipole antenna was used for the transmission antenna 13 and the reception antenna 14, the type of the antenna is not particularly limited, and a directional antenna may be used. Furthermore, the number of receiving antennas 14 is not limited to one, and a plurality of receiving antennas 14 may be used. When one omnidirectional transmitting antenna 13 and a plurality of receiving antennas 14 are used, it is preferable to use a dipole antenna.

  The receiving unit 15 is means for converting a signal received by the microwave transmitted by the receiving antenna 14 into a signal required by the detecting unit 16. The detector 16 is means for detecting the microwave received by the receiver 15. The detection unit 16 demodulates the microwave by envelope detection (amplitude detection) or phase detection.

  The sampling unit 17 is a means for sampling the detection signal at a predetermined frequency and converting it into a digital signal sequence.

  The estimation unit 11 is a means for instructing the transmission unit 12 to output a microwave and then analyzing the digital signal sequence received from the sampling unit 17 to estimate changes in cardiac volume and cardiac output. . Detailed operation will be described later.

  In the present embodiment, the estimation unit 11 is implemented as a function of a program executed by an information processing apparatus such as a general personal computer. The transmission unit 12, the reception unit 15, the detection unit 16, and the sampling unit 17 are mounted as electronic circuits (hardware) mounted on the information processing apparatus, and can be controlled by the estimation unit 11. Of course, each of the estimation unit 11, the transmission unit 12, the reception unit 15, the detection unit 16, and the sampling unit 17 may be implemented by a program, or may be implemented by an electronic circuit.

[Changes in microwaves]
Here, the change of the microwave transmitted through the human body 1 will be described with reference to FIG.

FIG. 3 is a diagram illustrating the microwaves before and after passing through the human body 1. In FIG. 3, the horizontal axis represents time, and the vertical axis represents electric field strength. 3 (a) is intended to indicate a time-series electric field intensity of the microwave radiated by the transmission antenna 13, the electric field strength is constant E _0. FIG. 3B shows, in time series, the electric field strength of the detection signal received by the receiving antenna 14 from the microwave transmitted through the human body 1 and detected by the detection unit 16.

  As described in Patent Document 1, when the human body 1 is irradiated with microwaves, a signal attenuation rate increases at a location where the dielectric constant is high compared to a location where the dielectric constant is low. Since the heart has a higher dielectric constant than the surrounding organs, the signal is attenuated more in the diastole than the systole, that is, the amplitude of the received microwave is reduced. As described above, when the heart is on a path through which the microwave passes and the movement in the body varies, the propagation characteristic of the microwave varies due to the displacement of the internal organs.

For example, FIG. 3A shows that a constant microwave is emitted with an electric field intensity E ₀ , but after passing through the human body, as shown in FIG.・ Microwaves whose electric field strength (amplitude) changes with expansion are observed. In this example, the electric field strength changes, but the phase of the microwave also changes due to the contraction and expansion of the heart.

  In this way, changes in the electric field strength and phase of the detection signal are considered to be information closely related to the contraction and expansion of the heart. By analyzing this, changes in the cardiac volume and cardiac output can be analyzed. Can be estimated.

[Estimation of changes in heart volume]
Here, a process for estimating a change in heart volume based on the detection signal will be described. FIG. 4 is a diagram showing the relationship between the electric field intensity of the microwave passing through the heart and the size of the heart.

Assuming that the shape of the heart is a sphere, its diameter is l [m], and its volume is V [m ³ ]. Further, the electric field intensity of the microwave radiated from the transmission antenna 13 is assumed to be E ₀ [V]. The electric field strength of the detection signal received by the detection unit 16 is E [V].

As described above, when the microwave passes through the heart, the electric field strength attenuates. This attenuation depends on the distance penetrating the heart. That is, the attenuation of the electric field strength is large when the heart is expanded and the diameter l is large, and the attenuation of the electric field strength is small when the heart is contracted and the diameter l is small. The relationship between the electric field strengths E ₀ and E before and after passing through the heart is expressed by the following mathematical formula 1.

  Here, α is an attenuation constant when the microwave passes through the heart. As the attenuation constant α, for example, the one shown in Formula 2 can be used.

The unit of the attenuation constant α is [Np / m], ω is the angular frequency [rad / s] of the microwave, and ε, σ, and μ are the dielectric constant, conductivity, and magnetic permeability of the heart, respectively.

  Rewriting equation 1 for diameter l assuming that the heart is spherical, equation 3 is obtained.

That is, it can be seen that the heart diameter l depends on the ratio of the electric field strengths E ₀ and E before and after passing through the heart. Here, since it is assumed that the heart is a sphere, if the radius of the heart is r, the heart volume V can be expressed by Equation 4. Then, when Formula 3 is substituted into Formula 4, Formula 5 is obtained.

Thus, the heart volume V depends on the third power of the ratio of the electric field strengths E ₀ and E before and after passing through the heart, and the heart volume V can be obtained from the electric field strengths E ₀ and E.

  Based on the principle described above, the estimation unit 11 estimates a change in the cardiac volume V. That is, the time-series heart volume V calculated based on the electric field strength is obtained. Specifically, the processing is as follows.

  First, data on dielectric constant ε, conductivity σ, and magnetic permeability μ are stored in advance in a memory or the like.

Next, the estimation unit 11 controls the transmission unit 12 so that microwaves are radiated from the transmission antenna 13 at the electric field intensity E ₀ and the angular frequency ω. The transmission unit 12 controlled by the estimation unit 11 irradiates the microwave from the transmission antenna 13 with the electric field intensity E ₀ and the angular frequency ω.

  The microwave irradiated from the transmitting antenna 13 passes through the heart 2 of the human body 1 and is received by the receiving unit 15 via the receiving antenna 14.

  The signal received by the receiver 15 is detected by the detector 16. As a detection method, amplitude detection (envelope detection) can be used. The detection signal detected by the detection unit 16 is sampled by the sampling unit 17.

  Sampling processing is performed by processing using an A / D converter or software. The processing of the sampling unit 17 can obtain a digital signal sequence representing the contraction / expansion of the heart with time and electric field intensity E (see FIG. 3B). The electric field intensity E in the i-th sampling period is represented as E (i).

  Next, the estimation unit 11 calculates the cardiac volume V using the digital signal sequence acquired from the sampling unit 17. Specifically, the attenuation constant α is calculated based on the above formula 2 from the dielectric constant ε, conductivity σ, and magnetic permeability μ stored in the memory.

Next, the cardiac volume V is calculated from the electric field intensity E ₀ set in the transmission unit 12, each E (i), and the attenuation constant α using the above formula 5. The heart volume V in the i-th sampling period is represented as V (i). Thereafter, the cardiac volume V (i) is calculated for all the sampled electric field strengths E (i). Thus, according to the estimation apparatus 10, time series data of the cardiac volume V (i) can be obtained.

  As described above, according to the estimation device 10, it is possible to estimate a change in the heart volume V without contact with the human body and without restraining the human body. That is, by looking at the time series transition of the heart volume V, it is possible to grasp the state of the heartbeat such as how fast the heart is contracting / expanding. Thus, since the state of the heartbeat can be grasped, it is possible to confirm, for example, diagnosis of heart failure, therapeutic effect or medication effect in prognosis without restraining the measurement subject and forcing a burden.

For example, the change in the cardiac volume V may be determined by determining a reference cardiac volume V ₀ and determining the ratio thereto. That is, V (i) / V ₀ may be calculated for each sampling period. Thereby, the relative heart volume based on the heart volume V ₀ can be grasped in time series.

[Estimation of changes in cardiac output]
Here, a process for estimating changes in stroke volume and cardiac output based on the detection signal will be described. Stroke volume is the amount of blood [mL] that the heart pumps into the artery due to a single contraction, and stroke volume is the stroke volume multiplied by the heart rate per unit time. Amount [mL / min].

  FIG. 5 is an example of a detection signal obtained by detecting a microwave transmitted through the heart. The vertical axis represents electric field strength [V], the horizontal axis represents time, and the detection signals are displayed in time series.

  The detection signal includes a periodic signal in which the electric field strength changes corresponding to the contraction / expansion of the heart. A range including the maximum value and the minimum value within a predetermined period included in the detection signal is set as a heartbeat signal corresponding to one heartbeat. A time-series heartbeat signal is obtained from the detection signal, and the i-th heartbeat signal is represented by S (i), the maximum value of the heartbeat signal is represented by Max (i), and the minimum value is represented by Min (i).

  For example, in the figure, the heart rate signal S including the maximum value Max (1) and the minimum value Min (1) as the first heart rate signal 1, and the maximum value Max (2) and the minimum value Min ( 2), the heartbeat signal S (2) is illustrated.

  The inventor examined the detection signal obtained according to the present invention by superimposing a separately acquired electrocardiogram. As a result, the range in which the heartbeat signal increases corresponds to the contraction of the heart, and the range in which the heartbeat signal decreases corresponds to the dilation of the heart. It was confirmed that it corresponds to.

  Given that the heart rate signal increases from the minimum value to the maximum value corresponds to the contraction of the heart and that the blood flow is pumped from the heart to the artery as the heart contracts, The maximum value of the signal is considered to correlate with the stroke volume. That is, it is considered that the stroke volume increases as the maximum value of the heartbeat signal increases.

  Therefore, if the heartbeat signal is obtained by passing through the left ventricle of the heart, the transition of the maximum value of the time-series heartbeat signal can be regarded as a change in stroke volume. For example, if Max (i) is substantially constant, it can be determined that the stroke volume is stable. If Max (i) repeats decreasing and increasing, it can be determined that the stroke volume is unstable. Thus, the change in stroke volume can be grasped by the time series change of Max (i). In addition, when it cannot be said that the heartbeat signal is obtained through the left ventricle of the heart, the transition of the maximum value of the time-series heartbeat signal is regarded as the change of the heart volume. In the following examples, it is assumed that the heartbeat signal is transmitted through the left ventricle, and the change in stroke volume is described. However, by replacing the stroke volume with the heart volume, Change.

Note that the change in stroke volume may be determined, for example, by determining a maximum value Max _{0 serving} as a reference and determining the ratio thereto. That is, Max ′ (i) = Max (i) / Max ₀ may be calculated. Thereby, the relative maximum value based on Max ₀ can be grasped in time series.

  The change in stroke volume can be estimated in addition to the transition of the maximum value of the heartbeat signal. For example, the difference between the maximum value and the minimum value included in the heartbeat signal is taken. This difference is referred to as a difference value.

  The state of the heart when the heartbeat signal is the minimum value is when it is most expanded, and the state of the heart when it is the maximum value is when it is most contracted. Therefore, the difference value is also considered to correlate with the stroke volume. That is, the larger the difference value, the greater the stroke volume.

  Therefore, the transition of the time-series difference value can be regarded as a change in stroke volume. If the difference value of the i-th heartbeat signal is A (i), for example, if A (i) is substantially constant, it can be determined that the stroke volume is stable. If A (i) repeatedly decreases and increases, it can be determined that the stroke volume is unstable. Thus, the change in stroke volume can be grasped by the time series change of A (i).

  Here, when estimating a change in the maximum value as a change in stroke volume, for example, when Max (i) and Max (j) are the same value, it is also determined that there is no change in stroke volume. it can. However, if Min (i) and Min (j) are different, there is a high possibility that the stroke volume has changed. On the other hand, since the difference value is the difference between the maximum value and the minimum value, in the above case, A (i) and A (j) are different values, and it can be determined that the stroke volume has changed.

  Thus, since the difference value is the difference between the maximum value and the minimum value, the change in stroke volume can be estimated more accurately.

The change in stroke volume, for example, determines the difference value A ₀ as a reference, it may be determined the ratio it. That is, A ′ (i) = A (i) / A ₀ may be calculated. Thus, it can be grasped in time series relative difference value relative to the A _0.

  Moreover, not only the change in stroke volume but also the change in cardiac output can be estimated. For example, a value obtained by integrating the maximum value of the heartbeat signal up to one minute before a certain point in time is set as the cardiac output estimated value. A change in cardiac output can be estimated by generating this cardiac output estimated value in time series. For example, if the estimated cardiac output is substantially constant, it can be determined that the cardiac output is stable, and if it is increased or decreased, it can be determined that it is unstable.

  The estimated cardiac output may be obtained not only by integrating the maximum value of the heartbeat signal but also by integrating the above-described difference values. Even in this case, a change in cardiac output can be estimated as in the case where the maximum values are integrated.

  Also, with respect to the estimated cardiac output value, a standard cardiac output estimated value may be determined and a ratio to the estimated cardiac output estimated value may be obtained. Thereby, the relative cardiac output estimated value with respect to the reference cardiac output estimated value can be grasped in time series.

  Based on the principle described above, the estimation unit 11 estimates a change in stroke volume. That is, a heartbeat signal is extracted, and a change in the maximum value or a difference value between the maximum value and the minimum value is obtained. Specifically, the processing is as follows. Note that the processing until obtaining the detection signal is the same as the processing for obtaining the heart volume, and therefore the description thereof is omitted.

  The estimation unit 11 extracts a heartbeat signal using the digital signal sequence acquired from the sampling unit 17. This detects a maximum value and a minimum value that exist within a predetermined cycle, and sets a single heartbeat signal from the first minimum value to the next minimum value. A heartbeat signal S (i) is obtained by applying this processing to the obtained digital signal sequence.

  Next, the maximum value Max (i) of each heartbeat signal S (i) is extracted. Alternatively, the difference value A (i) between the maximum value and the minimum value is calculated for each heartbeat signal S (i). In this way, according to the estimation device 10, it is possible to obtain time series data of the maximum value of the heartbeat signal or time series data of the difference value.

  As described above, according to the estimation device 10, it is possible to estimate changes in stroke volume and cardiac output without contact with the human body and without restraining the human body. That is, the change in the stroke volume and the cardiac output of the heart can be grasped by observing the time series transition of the maximum value or the difference value of the heartbeat signal. Thus, since the stroke volume and cardiac output of the heart can be grasped, it is possible to confirm, for example, diagnosis of heart failure, therapeutic effect or medication effect in prognosis without restraining the subject of measurement and imposing a burden. it can.

<Embodiment 2>
Although the estimation apparatus 10 according to the first embodiment irradiates the entire heart 2 of the human body 1 with microwaves, the estimation apparatus 10 is not limited to such an aspect.

  Using either horizontal polarization or vertical polarization properly, microwaves are applied to the right ventricle, right atrium, left ventricle, or left atrium of the heart to estimate the cardiac volume and stroke volume in each ventricle / atrium. It is also possible to do.

  For example, the transmitting antenna 13 may irradiate vertically polarized waves toward the heart, and the receiving antenna 14 may be arranged to receive vertically polarized waves transmitted through the right ventricle and right atrium of the heart. Thereby, the cardiac volume or stroke volume of the right ventricle and the right atrium can be estimated. Of course, the same applies to the left ventricle and the left atrium.

  The transmitting antenna 13 may be arranged so as to irradiate the horizontally polarized wave toward the heart, and the receiving antenna 14 may be arranged so as to receive the horizontally polarized wave transmitted through the right ventricle and the left ventricle of the heart. Thereby, the cardiac volume or stroke volume of the right ventricle and the left ventricle can be estimated. Of course, the same applies to the right atrium and the left atrium.

<Embodiment 3>
The estimation apparatus according to the present invention may be any apparatus having an antenna capable of transmitting and receiving microwaves and a calculation capability for detecting received radio waves and processing detected signals. Therefore, the estimation device can have a shape adapted to various usage environments.

  FIG. 6 is a schematic diagram of the estimation apparatus according to the present embodiment. As shown in the figure, the estimation apparatus 10 according to the present embodiment includes a cylindrical member 20 that is mounted around the chest of a human body.

  The cylindrical member 20 is a member such as a so-called belly wrap formed of stretchable fibers, for example. Of course, the cylindrical member 20 is not limited to such an embodiment, and a belt-like member formed of natural or artificial fibers may be rolled into a cylindrical shape and fixed. The cylindrical member 20 is attached so that the transmission antenna 13 and the reception antenna 14 face each other.

  Such a cylindrical member 20 is attached around the chest of a human body, and radio waves are transmitted and received between the transmitting antenna 13 and the receiving antenna 14 so as to pass through the heart.

  The transmission antenna 13 and the reception antenna 14 are connected to the smartphone 3. The smartphone 3 includes the estimation unit 11, the transmission unit 12, the reception unit 15, the detection unit 16, and the sampling unit 17 of the estimation device 10 described in the first embodiment as functions of an electronic circuit or software.

  In the smartphone 3, the estimation unit 11 calculates and accumulates the heart volume, stroke volume, and cardiac output in time series, so that the state of the heart can be recorded at home and the like. And the expert can judge the data recorded on the smart phone 3. According to the estimation apparatus 10 of such an aspect, the heart volume, stroke volume, and cardiac output can be grasped at home or the like without intervention of an expert. Diagnosis can be made.

  Moreover, since it functions as a cold protection like a stomach wrap, it can prevent the sense of being restrained by the wearer.

<Embodiment 4>
FIG. 7 is a schematic diagram of the estimation apparatus according to the present embodiment. As shown in the figure, the estimation apparatus 10 according to the present embodiment includes a bedding 30 on which a person goes to sleep.

  The transmitting antenna 13 is disposed on the floor side of the bedding, here the bedding 30, and the receiving antenna 14 is disposed above the bedding 30. Of course, the transmitting antenna 13 and the receiving antenna 14 may be disposed in reverse.

  According to the estimation apparatus 10 of such an aspect, it is possible to grasp the cardiac volume, stroke volume, and cardiac output without being restrained in a state where the human body lies on the bedding 30. it can.

DESCRIPTION OF SYMBOLS 1 Human body 2 Heart 10 Estimation apparatus 11 Estimation part 12 Transmission part 13 Transmission antenna 14 Reception antenna 15 Reception part 16 Detection part 17 Sampling part 20 Cylindrical member 30 Bedding

Claims (10)

Radio wave transmission means for radiating radio waves toward the heart of the measurement subject;
Radio wave receiving means for receiving radio waves transmitted through the heart of the measurement subject;
Detection means for detecting a detection signal by detecting a radio wave transmitted through the heart received by the radio wave reception means;
Estimating means for estimating a change in cardiac volume and cardiac output based on a change in amplitude or phase of the detection signal generated by attenuation of radio waves transmitted through the heart , and
The apparatus for estimating cardiac volume and cardiac output, wherein the radio wave transmitting means and the radio wave receiving means are disposed so as to face each other so that radio waves pass through the heart. The apparatus for estimating cardiac volume and cardiac output according to claim 1,
The estimation means includes
E0 is the intensity of the radio wave transmitted by the radio wave transmission means,
The intensity of the detection signal is E,
Let α be the attenuation constant of radio waves that pass through the heart,
Let the heart volume be V,
A time volume change of the heart volume V estimated by the following mathematical formula 1 is estimated as a change in heart volume. An estimation apparatus for heart volume and cardiac output.
The apparatus for estimating cardiac volume and cardiac output according to claim 1,
The estimation means sets a range including a maximum value and a minimum value within a predetermined period in the detection signal as a heartbeat signal corresponding to one heart beat, and a time series change of the maximum value as a stroke volume. An apparatus for estimating cardiac volume and cardiac output, characterized by estimating changes. The apparatus for estimating cardiac volume and cardiac output according to claim 3,
Accumulate the maximum value of the heart rate signal for a predetermined period to obtain an estimated cardiac output,
An apparatus for estimating cardiac volume and cardiac output, wherein the time series change of the cardiac output estimated value is estimated as a change in cardiac output. The apparatus for estimating cardiac volume and cardiac output according to claim 1,
The estimation means uses a range including a maximum value and a minimum value within a predetermined period of the detection signal as a heartbeat signal corresponding to one heartbeat, and a time-series change of a difference value between the maximum value and the minimum value An apparatus for estimating cardiac volume and cardiac output, characterized by estimating a stroke volume as a change in stroke volume. The apparatus for estimating cardiac volume and cardiac output according to claim 5,
The difference value of the heartbeat signal for a predetermined period is integrated to obtain an estimated cardiac output value,
An apparatus for estimating cardiac volume and cardiac output, wherein the time series change of the cardiac output estimated value is estimated as a change in cardiac output. In the estimation apparatus of the cardiac volume and cardiac output as described in any one of Claims 1-6,
The radio wave transmitting means irradiates vertically polarized waves toward the heart,
The apparatus for estimating cardiac volume and cardiac output is characterized in that the radio wave receiving means is arranged to receive vertically polarized waves transmitted through the right ventricle and right atrium or the left ventricle and left atrium of the heart. In the estimation apparatus of the cardiac volume and cardiac output as described in any one of Claims 1-6,
The radio wave transmitting means irradiates horizontally polarized waves toward the heart,
The apparatus for estimating cardiac volume and cardiac output is characterized in that the radio wave receiving means is arranged to receive horizontally polarized waves transmitted through the right ventricle and left ventricle of the heart or the right atrium and left atrium. In the cardiac volume and cardiac output estimation device according to any one of claims 1 to 8,
A cylindrical member that is worn around the chest of the human body,
An apparatus for estimating cardiac volume and cardiac output, wherein the tubular member is attached so that the radio wave transmission means and the radio wave reception means face each other. In the cardiac volume and cardiac output estimation device according to any one of claims 1 to 8,
Equipped with bedding,
Place one of the radio wave transmitting means and the radio wave receiving means on the floor side of the bedding,
An apparatus for estimating cardiac volume and cardiac output, wherein the other of the radio wave transmitting means and the radio wave receiving means is disposed above the bedding.