JP7283618B2 - Biological information measurement system - Google Patents

Description

The present invention relates to a biological information measuring system.

Conventionally, in medical institutions such as hospitals, systems have been used to continuously measure patient's respiratory rate, respiratory waveform, heart rate, heartbeat waveform, and other biological information using radio sensors to monitor for abnormalities. ing. In this system, measurement data of biological information is displayed on a terminal device or the like provided at the bedside, so that medical personnel such as doctors and nurses can check the measurement data.
As for the installation position of the sensor, it has been proposed to set it to the side or right below the mat (see, for example, Patent Document 1).

By the way, in recent years, in order to prevent pressure ulcers (bedsores) in patients without the intervention of nurses/caregivers, there have been opportunities to use electric air mattresses that cyclically move the contact area with the human body by inflating and deflating. It has increased.

WO2017/130646

However, when using the above air mattress, the movement of the air mattress may affect the sensor readings. In particular, when the sensor is installed directly under the mat as in Patent Document 1, it is directly affected by the air mat, which tends to affect the measured value.
In addition, when the sensor is installed next to the mat as in Patent Document 1, the entire sensor protrudes from the mat, which interferes with the actions of medical staff and patients and poses a problem in operability. In addition, in order to attach the sensor to the side of the mat so that it does not interfere with movement, it is necessary to fix it, for example, to a fence next to the bed. There is

SUMMARY OF THE INVENTION It is an object of the present invention to provide a biometric information measuring system which has good operability and can reduce the influence of the operation of an air mattress.

In order to solve the above problems, the biological information measurement system of the present invention includes:
A radio wave sensor that emits radio waves to a living body on the air mat that moves up and down due to expansion or contraction due to air supply and exhaust, and detects the movement of the living body using the reflected waves;
an arithmetic processing unit that acquires biological information of a living body on the air mattress from a detection signal output from the radio wave sensor;
with
The arithmetic processing unit acquires the biometric information by subtracting a component of a reference signal indicating the operation of the air mattress from the detection signal output from the radio wave sensor.

Advantageous Effects of Invention According to the present invention, it is possible to provide a biological information measurement system that has good operability and can reduce the influence of the operation of an air mattress.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the structure of the biological information measuring system of 1st Embodiment. FIG. 2 is a block diagram showing a functional configuration of the biological information measurement system of FIG. 1; 1 is an external view of a radio wave sensor; FIG. 4 is a cross-sectional view taken along line IV in FIG. 3; FIG. FIG. 4 is a diagram for explaining the arrangement of radio wave sensors; It is a figure for demonstrating the structure of a radio wave sensor. FIG. 4 is a diagram for explaining noise removal processing using an adaptive noise cancellation mechanism; It is a figure for demonstrating the noise removal process using a power spectrum. FIG. 10 is a diagram showing an arrangement example of a pair of radio wave sensors according to the second embodiment; It is a figure for demonstrating the signal processing in 2nd Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

<First embodiment>
[Configuration of biological information measurement system]
First, the configuration of the biological information measurement system 100 of this embodiment will be described.

FIG. 1 is a conceptual diagram showing the configuration of a biological information measuring system 100. As shown in FIG. FIG. 2 is a block diagram showing the functional configuration of the biological information measurement system 100. As shown in FIG.
As shown in FIGS. 1 and 2, the biological information measurement system 100 includes, for example, an air mattress device 10, a radio wave sensor 20 provided in the air mattress device 10, and a calculation for acquiring biological information from detection signals of the radio wave sensor 20. It comprises a device (arithmetic processing unit) 30 and a display device 40 for displaying the result of computation by the arithmetic device 30 .
Although the arithmetic device 30 and the display device 40 are separate here, they may be integrated.

[Air mattress device]
The air mattress device 10 is a bed device installed, for example, in a hospital room, on which a patient who is a user lies. The air mattress device may be a cushion device on which the patient sits.

The air mattress device 10 includes a bed frame 11 and an air mattress 12 .

The bed frame 11 includes a floorboard 11a, a headboard 11b surrounding the floorboard 11a, a footboard 11c, and rails 11d, 11d.
The floor plate 11a is a rectangular plate on which the air mattress 12 is placed. A headboard 11b and a footboard 11c are erected at both longitudinal ends of the floorboard 11a. Detachable fences 11d, 11d are erected on both sides of the floor plate 11a in the short direction.

The air mattress 12 has a plurality of air cells 12a, and is a so-called air mattress that can support the weight of a patient lying on the air mattress 12 by filling the inside of the air cells 12a with air. The plurality of air cells 12a constitute the air mattress 12 by being arranged side by side in the longitudinal direction of the air mattress 12, for example. The air cells 12a arranged adjacent to each other may or may not be fixed to each other.

A plurality of air cells 12a are divided into a plurality of groups. By alternately inflating or deflating the air cells 12a of each group at regular intervals, the air cells 12a for supporting the patient can be switched at regular intervals, and the thickness of the air mattress 12 can be partially changed. In addition, the thickness of the air mattress 12 can be changed as a whole by simultaneously inflating or deflating all the air cells 12a at regular intervals. Such expansion or contraction causes the air mattress 12 to move up and down.
The up-and-down movement of the air mattress 12 prevents the repulsive force from the air mattress 12 from being continuously applied to the same part of the patient's body for a long time. ), the effect of preventing stuffiness, the effect of facilitating getting out of bed, and the like can be obtained.

The air mattress 12 also includes an air supply/exhaust unit 13 and a mat control unit 14 .
The air supply/exhaust unit 13 includes, for example, a pump 13a that supplies air to the air cell 12a, an exhaust valve 13b that exhausts air from the air cell 12a, and a connection path that connects the air cell 12a, the pump 13a, and the exhaust valve 13b, respectively. , etc.
The mat control unit 14 measures the internal pressure of the air cell 12a by means of a measurement unit (not shown), outputs an ON/OFF signal based on the measurement result, and controls the pump 13a and the exhaust valve 13b.

[Radio wave sensor]
The radio wave sensor 20 is a sensor capable of detecting the movement of the patient without contacting the patient by radiating radio waves to the patient to be measured and detecting the reflected wave.
Specifically, the radio wave sensor 20 includes, for example, sensors such as Doppler, FMCW, and pulse Doppler.
The radio wave sensor 20 irradiates a patient with microwaves and detects the movement of the patient from changes in the frequency of the reflected microwaves. That is, when the patient moves, the frequency of the reflected wave changes due to the Doppler effect, so this frequency change is detected and a detection signal is output. When the patient does not move (including when there is no patient), the frequency does not change and a detection signal with no change is output.

FIG. 3 is an external view of the radio wave sensor 20. As shown in FIG. Moreover, FIG. 4 is sectional drawing in the IV line of FIG.
As shown in FIGS. 3 and 4, the radio wave sensor 20 includes a housing 21 having a housing space inside. The housing 21 includes a flat body portion 211 and a projecting portion 212 projecting upward from one longitudinal end portion of the body portion 211 .

Inside the housing 21, an antenna 22, a main substrate 23 having a radio wave detection circuit, a communication connector 25 connected to a communication cable 24, a holding member 26 for integrally holding them, and the like are accommodated.
The antenna 22 transmits a transmission signal output from the radio wave detection circuit as radio waves of a predetermined frequency. Further, the antenna 22 receives radio waves (reflected waves) among the transmitted radio waves that are reflected back to the patient (living body) and outputs reception signals.
The radio wave detection circuit generates a transmission signal of a predetermined frequency, outputs the generated transmission signal to the antenna 22 , and detects radio waves received by the antenna 22 .

The radio wave sensor 20 is arranged below the air mattress 12 at a position where at least part of it overlaps the lower surface of the edge of the air mattress 12 . That is, as shown in FIG. 1, the radio wave sensor 20 is arranged so as to be inserted between the air mattress 12 and the floor plate 11a. Alternatively, the air mattress 12 may be placed on the radio wave sensor 20 placed on the floor plate 11a.

Further, the radio wave sensor 20 is arranged so that the radio waves radiated from the antenna 22 are oriented toward the center of the upper surface of the air mattress 12 .
Specifically, when the antenna 22 is a patch antenna, the half-value width is about ±30 degrees, and it is preferable that the patient is within this half-value width. It is installed at an angle of about 40 to 80 degrees.
At this time, as shown in FIG. 5, it is preferable that the direction in which the directivity of the radio waves emitted from the antenna 22 of the radio wave sensor 20 is maximized is different from the direction in which the air mattress 12 moves most. By doing so, it is possible to obtain a large signal value while reducing the influence of the vertical movement of the air mattress 12, thereby enabling effective measurement.

The shape of the housing 21 is formed according to such an installation angle of the antenna 22 . Antenna 22 is housed inside.
Then, it is inserted from the body portion 211 of the radio wave sensor 20 to below the air mattress 12 (between the air mattress 12 and the floor plate 11a) and arranged at a predetermined position. From the viewpoint of improving operability, it is preferable that the entire radio wave sensor 20 overlaps the lower surface of the edge of the air mattress 12. However, as shown in FIG. may protrude outward from the edge of the

Further, in the state where the radio wave sensor 20 is arranged as described above, the height of the radio wave sensor 20 (the height of the projecting portion 212) is preferably equal to or less than the thickness of the air mattress 12. By doing so, it is possible to prevent the patient from feeling uncomfortable due to unevenness of the air mattress 12 due to the installation of the radio wave sensor 20 .

Note that if the antenna 22 is an array antenna whose directivity can be controlled, the antenna 22 may be configured not to be tilted with respect to the main board 23 . In this case, the entire radio wave sensor 20 is formed in a flat shape, and the entire radio wave sensor 20 is inserted below the air mattress 12 (between the air mattress 12 and the floor plate 11a) and arranged at a position overlapping the lower surface of the edge of the air mattress 12. is set.

FIG. 6 is a diagram for further explaining the configuration of the radio wave sensor 20. As shown in FIG.
As shown in FIG. 6, the rear surface of the projecting portion 212 of the housing 21 is open, and this opening is closed by a holding member 26 housed inside the housing 21. It is also preferable that the holding member 26 can be pulled out from the rear opening.
By doing so, even when the patient lies on the air mattress 12 and the radio wave sensor 20 remains installed, the internal parts of the radio wave sensor 20 can be replaced or maintained.

Further, in this embodiment, a pressure sensor 50 is provided between the air mattress 12 and the floor plate 11a.
The pressure sensor 50 is placed at a position that minimizes overlap with the patient's body (eg, under the corners of the air mattress 12).

[Arithmetic unit]
The computing device 30 includes, for example, a CPU (Central Processing Unit), a storage device storing a control program and control data, and a memory in which the CPU develops data.
The arithmetic unit 30 executes the control program by the CPU to process the detection signal output from the radio wave sensor 20 and perform the arithmetic operation.

[Display device]
The display device 40 is, for example, a device that is provided at the patient's bedside and displays the calculation result of the calculation device 30 . The display device 40 may be, for example, a monitoring device provided at a nurse station, or a mobile terminal device carried by a medical worker such as a doctor or a nurse.
The display device 40 is configured with, for example, an LCD (Liquid Crystal Display) or the like, and displays various screens according to instructions of display signals input from the arithmetic device 30 .
The display device 40 can switch and display a plurality of screens including a screen for displaying biological information (measured values, measured waveforms, etc.).

[Signal processing by arithmetic unit]
Next, signal processing by the computing device 30 of the biological information measurement system 100 will be described.

In the present embodiment, computing device 30 calculates biological information based on the detection signal output from radio wave sensor 20 and the reference signal indicating the operation of air mattress 12 .

Specifically, when a detection signal is output from the radio wave sensor 20, the computing device 30 converts the detection signal into a distance signal or a speed signal.
For example, to obtain the distance signal from the detection signal (IQ signal) of the radio wave sensor 20, the following formula (1) can be used. Here, the angle θ is the distance signal.
θ=arctan(Q/I) (1)

The computing device 30 also acquires a reference signal from the pressure sensor 50 .
Here, the reference signal is a signal indicating pressure change due to movement of the air mattress 12 detected by the pressure sensor 50 .
By arranging the pressure sensor 50 at a position that does not overlap with the patient's body as much as possible, it generates a reference signal that indicates only the movement of the air mattress 12 without being affected by the patient's movement.

Next, the arithmetic unit 30 performs noise removal processing for subtracting the component of the reference signal from the distance signal or speed signal.
A method using an adaptive noise canceling mechanism, a method using a power spectrum, or the like is used as noise removal processing.

FIG. 7 is a diagram for explaining noise removal processing using an adaptive noise cancellation mechanism.
As shown in FIG. 7, the adaptive noise canceling mechanism uses an adaptive filter to output a signal that suppresses the operation (noise) of the air mattress 12 .
Specifically, an input signal obtained by converting the detection signal (IQ signal) of the radio wave sensor 20 into a distance signal or a speed signal is input to the adaptive noise cancellation mechanism. Such input signals include noise signals resulting from the motion of the air mattress 12 in addition to biological signals resulting from the motion of the patient. Then, the adaptive filter filters an undesired frequency region (noise signal caused by the operation of the air mattress 12) from the input signal, thereby outputting a signal from which the noise signal is subtracted. Since this output signal is obtained by removing the noise signal from the input signal, its peak frequency can be estimated as biological information (respiratory rate, etc.).

FIGS. 8A to 8C are diagrams for explaining noise removal processing using a power spectrum.
As shown in FIG. 8(a), the input signal obtained by converting the detection signal (IQ signal) of the radio wave sensor 20 into a distance signal or speed signal is subjected to FFT such as Fourier transform and power conversion to obtain a power spectrum. .
Similarly, the power spectrum of the reference signal is obtained as shown in FIG. 8(b). It is preferable that the maximum value of the peak frequency of the reference signal is normalized so as to be the same as the value of the same frequency of the input signal.
Then, the power spectrum of the reference signal is subtracted from the power spectrum of the detection signal of the radio wave sensor 20 to obtain a power spectrum from which noise has been removed, as shown in FIG. 8(c). The peak frequency of the power spectrum of FIG. 8(c) is biological information (respiratory rate, etc.).

As the reference signal, the movement distance of the air mattress 12 in the thickness direction, the movement speed of the air mattress 12 in the thickness direction, etc. can also be used. In this case, instead of the pressure sensor 50, a distance sensor or speed sensor may be used. Sensors using radio waves, lasers, ultrasonic waves, or the like are used as distance sensors and speed sensors.

[Effects of Embodiment]
As described above, according to the present embodiment, the biological information measurement system 100 irradiates the air mattress 12, which moves up and down due to expansion or contraction due to air supply/exhaust, and the patient on the air mattress 12, and the reflected wave and a computing device 30 for acquiring biological information of the patient on the air mattress 12 from the detection signal output from the radio wave sensor 20. The radio wave sensor 20 Under the air mattress 12, at a position where at least a part overlaps with the lower surface of the edge of the air mattress 12, the radio wave sensor 20 is arranged so that the directivity of the radio waves emitted from the radio wave sensor 20 is directed toward the center of the upper surface of the air mattress 12. be done.
For this reason, since the radio wave sensor 20 is arranged below the air mattress 12 and at least a part of it overlaps the lower surface of the edge of the air mattress 12, it can be operated without interfering with the actions of medical staff and patients. can improve the quality.
Further, since the radio wave sensor 20 is arranged below the air mattress 12 and at least partially overlaps with the lower surface of the edge of the air mattress 12, compared to the case where the sensor is installed directly under the air mattress, for example, the air mattress 12, and the influence on the measured value can be suppressed.
In addition, since the air mattress 12 can be inserted between the support portion (here, the floor plate 11a) that supports the air mattress 12 therebelow, the ease of installation can be improved.

Further, according to the present embodiment, the direction in which the directivity of radio waves emitted from radio wave sensor 20 is maximized is different from the direction in which air mattress 12 moves most.
For this reason, it is possible to obtain a large signal value while reducing the influence of the operation of the air mattress 12, thereby enabling effective measurement.

Further, according to the present embodiment, the height of the radio wave sensor 20 when arranged with respect to the air mattress 12 is equal to or less than the thickness of the air mattress 12 .
Therefore, it is possible to prevent the patient from feeling uncomfortable due to the installation of the radio wave sensor 20 .

Further, according to the present embodiment, arithmetic device 30 acquires biological information based on the detection signal output from radio wave sensor 20 and the reference signal indicating the operation of air mattress 12 .
Specifically, the computing device 30 subtracts the component of the reference signal from the detection signal output from the radio wave sensor 20 to acquire the biometric information.
The reference signal is a signal that indicates any one of the movement distance of the air mattress 12 in the thickness direction, the movement speed of the air mattress 12 in the thickness direction, and the pressure change caused by the movement of the air mattress 12 .
Therefore, more accurate measurement is possible.

An ON/OFF signal of at least one of the pump 13a and the exhaust valve 13b of the air mattress 12 may be used as the reference signal.
In this case, when the computing device 30 determines from the reference signal that at least one of the pump 13a and the exhaust valve 13b of the air mattress 12 is in operation, the detection signal output from the radio wave sensor 20 (or obtained from the detection signal biometric information received) is judged to be invalid.

In addition, in the above-described embodiment, one radio wave sensor 20 is provided, but a plurality of radio wave sensors 20 may be installed.
Further, in the above-described embodiment, the radio wave sensor 20 is arranged along one side of the air mattress 12 in the longitudinal direction, but it may be arranged along one side of the air mattress 12 in the transverse direction. That is, it may be arranged near the patient's head or feet.
Even in this case, the radio wave sensor 20 is located below the air mattress 12 and at least partially overlaps the lower surface of the edge of the air mattress 12 so that the directivity of the radio waves is directed toward the center of the upper surface of the air mattress 12. It will be arranged as follows.

Further, the operation information of the air mattress 12 when there is no patient on the air mattress 12 is measured and stored as a reference signal, and the stored operation information of the air mattress 12 is obtained from the measurement value of the radio wave sensor 20 when the patient is present. may be used to subtract the influence of air mattress operation.

Further, the calculation device 30 may acquire biological information without performing the above-described processing using the reference signal.

<Second Embodiment>
Next, a second embodiment of the present invention will be described, focusing on points different from the first embodiment. It should be noted that the same reference numerals are given to the same configurations as in the first embodiment, and the description thereof will be omitted.

[Configuration of biological information measurement system]
The biological information measuring system according to the present embodiment includes a second radio wave sensor 60 in addition to the radio wave sensor 20 .
The radio wave sensor 20 and the second radio wave sensor 60 form a pair, and the second radio wave sensor 60 is arranged to face the radio wave sensor 20 with the air mattress 12 interposed therebetween.
The configuration of the second radio wave sensor 60 is the same as that of the radio wave sensor 20, but the frequencies of the generated radio waves are set to be different from each other.

9A and 9B are diagrams showing an example of the arrangement of the radio wave sensor 20 and the second radio wave sensor 60. FIG.
In FIG. 9A, one radio wave sensor 20 is disposed at a position overlapping the lower surface of the edge of the air mattress 12 in the width direction (the edge on the foot side), and the other second radio wave sensor 60 is It is an example arranged at a position above the patient's head. The antenna surfaces of the two sensors 20, 60 are installed so as to face each other.
9(b), one radio wave sensor 20 is disposed at a position overlapping the lower surface of one longitudinal edge of the air mattress 12, and the other second radio wave sensor 60 is disposed in the longitudinal direction of the air mattress 12. It is an example arranged at a position above the other edge of the direction. The antenna surfaces of the two sensors are placed facing each other.

[Signal processing by arithmetic unit]
In this case, as shown in FIG. 10, the computing device 30 obtains a synthesized signal from the distance or speed signal obtained from the respective detection signals of the paired radio wave sensors 20 and 60, and obtains the biometric information from the synthesized signal. The combined signal may be the sum of the two signals, or the average of the two signals.

As a result, for example, when the whole patient moves in the same direction, the increases and decreases in the distance or velocity signals obtained from each of the paired radio wave sensors 20 and 60 are offset because they move in opposite directions, and are synthesized. The signal becomes a signal from which the body motion component has been removed (or reduced).
Also, when the patient's volume expands or contracts as in respiration, the distance or velocity signals obtained from the paired radio wave sensors 20 and 60 move in the same direction. It is more emphasized and the influence of noise can be reduced.
Also, even if the patient is biased on the air mattress 12, the signal from one of the paired radio wave sensors 20 and 60 is strengthened, so that the combined signal can reduce the influence of bias.

After obtaining the biological information (respiratory rate and heart rate) from each sensor, if the final biological information is calculated by averaging, etc., the correlation between the distance or speed signals originally obtained from each sensor will be lost. Information is discarded, but by doing so, it is possible to make effective use of the information on the correlation of the phase information of each sensor, and to reduce the influence of disturbance such as body movement.

[Effects of Embodiment]
As described above, according to the present embodiment, the second radio wave sensor 60 is arranged to face the radio wave sensor 20 with the air mattress 12 interposed therebetween. A composite signal is obtained from the distance or speed signal obtained from each detection signal of the radio wave sensor 60, and biological information is obtained from the composite signal.
Therefore, it is possible to reduce the influence of disturbances such as body movements, so that more accurate measurement is possible.

It is of course possible to perform arithmetic processing using a reference signal also in the present embodiment, as in the first embodiment.

Moreover, the pair of radio wave sensors is not limited to one set, and a plurality of sets may be provided. For example, a configuration including both sets of FIGS. 9A and 9B can be used.

Embodiments to which the present invention can be applied are not limited to the above-described first and second embodiments, and can be changed as appropriate without departing from the gist of the present invention.

For example, in order to increase the reflectance of the radio wave sensor, a reflector (aluminum foil, a plate coated with aluminum foil, etc.) that reflects radio waves from the sensor may be placed on the upper surface of the air mat 12 .

100 Biological information measurement system 10 Air mattress device 11 Bed frame 11a Floor board 11b Headboard 11c Footboard 11d Rail body 12 Air mattress 12a Air cell 13 Air supply/exhaust unit 13a Pump 13b Exhaust valve 14 Mat control unit 20 Radio wave sensor 21 Housing 211 Main unit 212 Projection Part 22 Antenna 23 Main substrate 24 Communication cable 25 Communication connector 26 Holding member 30 Arithmetic device (arithmetic processing unit)
40 display device 50 pressure sensor 60 second radio wave sensor

Claims (2)

A radio wave sensor that emits radio waves to a living body on the air mat that moves up and down due to expansion or contraction due to air supply and exhaust, and detects the movement of the living body using the reflected waves;
an arithmetic processing unit that acquires biological information of a living body on the air mattress from a detection signal output from the radio wave sensor;
with
The biological information measuring system, wherein the arithmetic processing unit acquires the biological information by subtracting a component of a reference signal indicating the operation of the air mattress from the detection signal output from the radio wave sensor. 2. The biological information measurement according to claim 1 , wherein the reference signal is a signal indicating a moving distance of the air mattress in the thickness direction, a moving speed of the air mattress in the thickness direction, or a pressure change due to the movement of the air mattress. system.

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