WO2020203020A1 - Biological information measurer and biological information measurement method using same - Google Patents

Abstract

The present invention provides a biological information measurer provided with: a biological signal acquisition unit which acquires a biological signal of a subject, which is output from a biosensor including a PPG sensor; a posture state signal acquisition unit which acquires a posture state signal of the subject, which is output from a motion sensor; a posture state estimation unit which estimates a posture state of the subject on the basis of the posture state signal acquired by the posture state signal acquisition unit; and an SpO2 calculation unit which calculates SpO2 of the subject at the time of being in a reference posture state on the basis of the biological signal acquired by the biological signal acquisition unit and the posture state estimated by the posture state estimation unit. The SpO2 calculation unit calculates the SpO2 by applying, to an absorbance ratio calculated on the basis of the acquired biological signal, a prescribed parameter set according to the estimated posture state.

Description

Biometric information measuring instrument and biometric information measuring method using it

The present invention relates to a biological information measuring device and a biological information measuring method using the same.

Photoplethysmography (PPG) is one of the methods for non-invasively monitoring the biological signal and biological information of a subject. PPG is a method of monitoring changes in blood flow in a living tissue by irradiating the surface of the living body of a subject with light having a predetermined wavelength and measuring a time-series change in the amount of light reflected or transmitted therethrough. Since blood flow is affected by multiple biological systems, by measuring biological signals with PPG, for example, pulse rate (HB), heart rate variability (HRV), vascular elasticity (RI), arterial oxygen saturation Various biological indicators such as (SpO2) and local tissue oxygen saturation (rSO2) can be obtained.

In the measurement by PPG, the vascular system changes depending on how each part of the body bends, and the body composition changes due to the movement of fat and muscle, depending on the posture and / or body movement of the subject. In the past, when highly accurate measurements were required, the subject was assigned a resting posture and was forced to remain in that posture during the measurement. Therefore, if the posture of the subject changes during the measurement, the correct measurement result may not be obtained.

Patent Document 1 shown below discloses a technique for accurately obtaining a causal relationship between a subject's body movement and respiratory disease symptoms. Specifically, Patent Document 1 describes a sleep evaluation system composed of a pulse oximeter and a PC, and the pulse oximeter obtains measurement data regarding blood oxygen saturation information from a subject's measuring finger. The PC includes a probe to be acquired, a 3-axis acceleration sensor that acquires measurement data related to the body movement information of the subject, and a storage unit that stores the measurement data measured by the probe and the 3-axis acceleration sensor. A sleep evaluation system having a processing function of acquiring measurement data stored in the unit and analyzing the relationship between the fluctuation of blood oxygen saturation and the body movement of a subject is disclosed.

Japanese Unexamined Patent Publication No. 2006-263504

However, the above technique shown in Patent Document 1 simply determines whether or not the blood oxygen saturation decreases in synchronization with the body movement of the subject in the diagnosis of the subject having a respiratory disease. It stopped and was not aimed at accurately determining the subject's blood oxygen saturation itself. That is, originally, the blood oxygen saturation concentration should be measured in a state where the subject takes a correct posture at rest, and the correct value should be obtained. However, in the above technique, the posture of the subject has changed. The blood oxygen saturation concentration measured and shown in this case deviates from the value that should be measured in the original ideal state.

Therefore, the present invention provides a biological information measuring device capable of accurately calculating the biological information even when the posture and / or body movement of the subject changes, and a biological information measuring method using the same. The purpose is.

More specifically, one object of the present invention is to make a correction according to the posture and / or body movement of the subject even if the posture and / or body movement of the subject changes. It is an object of the present invention to provide a biological information measuring device capable of more accurately calculating the above and a biological information measuring method using the same.

The present invention for solving the above problems is configured to include the following invention-specific matters or technical features.

The present invention according to a certain viewpoint is a biological information measuring instrument. The biological information measuring device may include a biological signal acquisition unit that acquires the biological signal of the subject and a posture state signal acquisition unit that acquires the posture state signal of the subject. The biological signal of the subject can be output from a biological sensor including a PPG sensor. Further, the posture state signal of the subject can be output from the motion sensor. The biological information measuring device further includes a posture state estimation unit that estimates the posture state of the subject based on the posture state signal acquired by the posture state signal acquisition unit, and the biological signal acquired by the biological signal acquisition unit. And the SpO2 calculation unit that calculates SpO2 in the reference posture state of the subject based on the posture state estimated by the posture state estimation unit. The SpO2 calculation unit can calculate the SpO2 by applying a parameter set according to the estimated posture state to the absorbance ratio calculated based on the acquired biological signal.

The biological information measuring instrument may further include a parameter set storage unit that stores a plurality of parameter sets corresponding to a plurality of posture state models.

Further, the biological information measuring device may further include a parameter set selection unit that selects one of the predetermined parameter sets corresponding to the estimated posture state from the parameter set storage unit. Then, the SpO2 calculation unit can correct the absorbance ratio based on the selected predetermined parameter set.

Further, the biometric information measuring instrument selects one or two or more of the parameter sets corresponding to the estimated posture state from the parameter set storage unit, and performs interpolation based on the selected one or more parameter sets. Further, a parameter set estimation unit for estimating one parameter set may be provided by calculation. Then, the SpO2 calculation unit can correct the absorbance ratio based on the estimated one parameter set.

Further, the SpO2 calculation unit can correct the absorbance ratio by the interpolation calculation using the probability density function. Alternatively, the SpO2 calculation unit can correct the absorbance ratio by the interpolation calculation using a predetermined nonlinear function.

Further, the biometric information measuring instrument may further include a parameter set estimation unit that estimates a parameter set corresponding to a specific posture state based on the estimated posture state and the absorbance ratio. Then, the parameter set estimation unit may store the estimated parameter set in the parameter set storage unit.

Further, the posture state estimation unit can estimate the posture state of the subject based on the biological signal output from at least one biological sensor.

Further, the at least one biosensor may include at least one of a blood pressure sensor, a pulse sensor, an ECG sensor and an myoelectric sensor.

Further, the motion sensor includes at least one of a gravity sensor, an acceleration sensor, a gyro sensor, a geomagnetic sensor, a pressure sensitive sensor, an ultrasonic sensor, an infrared sensor, an image sensor, and a spectrum sensor.

Further, the present invention according to another viewpoint can be a biometric information measuring method using a biometric information measuring device. The method may include obtaining a biological signal of the subject and obtaining a posture state signal of the subject. The biological signal of the subject can be output from a biological sensor including a PPG sensor. Further, the posture state signal of the subject can be output from the motion sensor. The method also estimates the posture state of the subject based on the acquired posture state signal, and at the time of the reference posture state of the subject based on the acquired biological signal and the estimated posture state. It may include calculating SpO2. Then, to calculate the SpO2, the SpO2 is calculated by applying a parameter set according to the estimated posture state to the absorbance ratio calculated based on the acquired biological signal. May include.

Furthermore, the present invention according to another viewpoint can also be configured as a computer program for executing the method and a recording medium on which the method is executed in a computing device under the control of a processor.

Note that, in the present specification and the like, the "means" does not simply mean a physical means, but also includes a means in which the function of the means is realized by software. Further, the function of one means may be realized by two or more physical means, or the function of two or more means may be realized by one physical means.

Further, in the present disclosure, the "system" includes a device in which a plurality of devices (or functional modules that realize a specific function) are logically assembled, and each device or functional module is physically a single device. It does not matter whether it is composed or as a separate object.

According to the present invention, even when the posture and / or body movement of the subject changes, the biological information can be accurately calculated.

Other technical features, objectives, effects and advantages of the present invention will be clarified by the following embodiments described with reference to the accompanying drawings.

It is a block diagram which shows an example of the structure of the biological information measuring instrument which concerns on one Embodiment of this invention. It is a block diagram for demonstrating the detail of the control part of the biological information measuring instrument which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the structure of the biological information measuring instrument which concerns on one Embodiment of this invention. It is a figure which shows an example of the parameter mixing ratio map in the biological information measuring instrument which concerns on one Embodiment of this invention. It is a figure which shows an example of the body composition distribution assumed according to the posture state of a subject. It is a figure which shows an example of the body composition distribution assumed according to the posture state of a subject. It is a block diagram which shows an example of the structure of the biological information measuring instrument which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the structure of the biological information measuring instrument which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples, and there is no intention of excluding the application of various modifications and techniques not specified below. The present invention can be implemented in various modifications (for example, by combining each embodiment) without departing from the spirit of the present invention. Further, in the description of the following drawings, the same or similar parts are designated by the same or similar reference numerals. The drawings are schematic and do not necessarily match the actual dimensions and ratios. Even between drawings, parts with different dimensional relationships and ratios may be included.

[First Embodiment]
In the present embodiment, when measuring SpO2, the posture state of the subject is observed, the optimum parameter set according to the observed posture state is selected, and the selected parameter set is applied to the calculated absorptivity ratio. , A biological information measuring instrument for calculating SpO2 and a measuring method using the same will be described.

FIG. 1 is a block diagram showing an example of the configuration of the biological information measuring instrument according to the embodiment of the present invention. The biometric information measuring device 1 shown in the figure is a device for measuring SpO2, which is one of the biometric indexes of the subject. For example, the sensor unit 10, the control unit 20, and the user interface unit 30 communicate with each other. It includes components such as the interface unit 40. The biological information measuring instrument 1 is generally referred to as a pulse oximeter, but is not limited thereto. The biometric information measuring instrument 1 may be configured as an integrated type in which these components are housed in one housing (not shown), for example. Such an integrated biometric information measuring device 1 can be attached to, for example, the chest or a finger of a subject. As another example, the biometric information measuring instrument 1 may be configured such that all or a part of the sensor unit 10 and the like is separate from the housing. Alternatively, several components, for example, the control unit 20, the user interface unit 30, and the communication interface unit 40 may be integrally configured as one controller board or a control device main body. Alternatively, the biometric information measuring device 1 may be configured such that a part of the functions of the control unit 20 is executed by an external device (for example, a computing device).

The sensor unit 10 includes, for example, at least one biosensor 12 and at least one motion sensor 14. The biological sensor 12 is a sensor that observes a biological phenomenon of a subject, detects and outputs a biological signal based on the biological phenomenon. The biosensor 12 typically includes a PPG sensor 12a for measuring SpO2 (see FIG. 2). As is obvious to those skilled in the art, the PPG sensor 12a is an active unit including a light emitting unit for emitting light of two types of wavelengths (red light and infrared light) and a light receiving unit for receiving these lights. It is a sensor, and there are, for example, a transmissive type and a reflective type. In the present disclosure, it is assumed that the PPG sensor 12a is a reflective type, but the present invention is not limited to this. The reflection type PPG sensor 12a receives the reflected light (which may include scattered light, diffused light, etc.) from the living body irradiated with the light. Further, as will be described later, the biological signal detected by the PPG sensor 12a can be used to estimate the posture and / or body movement state (hereinafter referred to as “posture state”) of the subject. In other words, the change in the biological signal detected by the PPG sensor 12a can be regarded as the change in the posture state of the subject. The posture state may include a state of movement of a specific part such as raising and lowering the subject's hand and upper arm. Further, the biological sensor 12 may include at least one of a blood pressure sensor, a pulse sensor, an ECG sensor, and an electromyographic sensor. At least some of these biological sensors 12 are attached to, for example, a measurement site or location of a subject according to the characteristics of the sensor to detect biological signals. The biological signal detected by the biological sensor 12 is output to the control unit 20.

The motion sensor 14 is a sensor that observes the posture state of the subject, detects and outputs a signal related to the posture state (hereinafter referred to as "posture state signal"). A known motion sensor 14 can be used. As an example, the motion sensor 14 includes a gravity sensor, an acceleration sensor, a gyro sensor (these may be collectively referred to as an "inertial sensor"), a geomagnetic sensor, a pressure sensor, an ultrasonic sensor, an infrared sensor, and an image sensor. , And at least one of the spectrum sensors. The posture state signal detected by the motion sensor 14 is output to the control unit 20. Some of the motion sensors 14 are not directly attached to the subject, and may be configured and arranged so as to observe from a position away from the subject, for example. For example, the image sensor may be configured to image the subject as a camera and output the imaged signal to the biometric information measuring instrument 1 or an external computing device.

The control unit 20 is typically configured to include a processor 22 and a memory 24, and is a component that comprehensively controls the operation of the biometric information measuring device 1 under the control of the processor 22. The memory 24 holds, for example, a processing program and various setting information. The processing program may be configured to include, for example, several program modules. Further, in the present embodiment, the memory 24 is configured to store one or more parameter sets necessary for calculating SpO2, which will be described later, and to store the calculated SpO2 as a measurement result. For example, the control unit 20 collaborates with other components by executing a predetermined processing program under the control of the processor 22, calculates SpO2 based on the acquired biological signal and posture state signal, and calculates SpO2. This is stored in the memory 24 as a measurement result. In this sense, the control unit 20 functions as a computing device. The measurement result may include, for example, a time stamp indicating the time when SpO2 was measured. In the present embodiment, the calculated SpO2 is the SpO2 estimated in the reference posture state in consideration of the subject's current posture state. Details of the calculation of SpO2 will be described later.

The user interface unit 30 is a component that provides a user interface that functions interactively to a subject and / or a medical worker such as a doctor (hereinafter, these persons may be collectively referred to as a "user"). is there. The user interface unit 30 receives, for example, an input operation from the user under the control of the processor 22, and / or displays, for example, the calculated SpO2 measurement result or the like to the user. As a simple configuration example of the user interface unit 30, it can be realized by a power button and a display such as an LED or an LCD. Further, the user interface unit 30 may include a speaker, a vibrator, and the like. As another example, the user interface unit 30 may be a touch panel. For example, the user can interactively operate the user interface unit 30 as a touch panel to display necessary information and make various settings of the biometric information measuring device 1.

In the present disclosure, the user interface unit 30 is configured as a part of the biometric information measuring device 1, but is not limited to this. For example, a part or all of the user interface unit 30 may be realized by an external computing device. As an example, an external computing device is configured to be communicable with a control unit 20 via a communication interface unit 40, and a user operates a Web browser on the computing device to perform measurement results and / or the measurement results. You can refer to the analysis result for. With such a configuration, the biometric information measuring instrument 1 does not need to have the user interface unit 30, or may have a minimum configuration, and its housing size can be reduced.

The communication interface unit 40 is a component for connecting the biometric information measuring device 1 so as to be able to communicate with an external device. The connection form between the communication interface unit 40 and the external device is not limited to wired and / or wireless, and the communication interface unit 40 adopts a configuration according to such a connection form. For example, the communication interface unit 40 may be designed in accordance with a USB standard, a Bluetooth (registered trademark) standard, a Wi-Fi (registered trademark) standard, or the like. As an example, the communication interface unit 40 is defined as a USB mass storage class, and the measurement result stored in the memory 24 of the biometric information measuring device 1 is read out by an external device.

FIG. 2 is a block diagram for explaining the details of the control unit of the biometric information measuring instrument according to the embodiment of the present invention. As shown in the figure, the control unit 20 of the biological information measuring device 1 includes, for example, a sensor control unit 201, a biological signal receiving unit 202, an attitude state signal receiving unit 203, an absorptivity ratio calculation unit 204, and an attitude state. It includes an estimation unit 205, a parameter set storage unit 206, a parameter set selection unit 207, a SpO2 calculation unit 208, and a measurement result storage unit 209. Further, in this example, the PPG sensor 12a is shown as the biosensor 12 of the sensor unit 10, and the inertial sensor 14a and the triaxial geomagnetic sensor 14b are shown as the motion sensor 14. The inertial sensor 14a typically includes a 3-axis acceleration sensor and a 3-axis gyro sensor, and in combination with the 3-axis geomagnetic sensor 14b, functions as a 9-axis motion sensor. As described above, the motion sensor 14 is not limited to these sensors, and may include a camera such as an image sensor or a spectrum sensor, for example.

The sensor control unit 201 controls the operation of the sensor unit 10. For example, the sensor control unit 201 performs light emission control for driving the light emitting unit of the PPG sensor 12a in order to start the measurement of SpO2 in accordance with the instruction from the user interface unit 30 based on the user's operation.

Receives or acquires the biological signal output from the biological signal receiving unit 202 and the PPG sensor 12a. In the biological signal output from the PPG sensor 12a, the red light (for example, wavelength λ1 = 660 to 670 nm or its vicinity) emitted by the first light emitting portion (not shown) is typically a biological tissue (arterial blood). The signal component based on the first reflected light obtained by irradiating the living body and the infrared light (for example, wavelength λ2 = 880 to 940 nm or its vicinity) emitted by the second light emitting portion (not shown) are living organisms. It includes a signal component based on the second reflected light obtained by irradiating the tissue. The biological signal receiving unit 202 is an example of the biological signal acquisition unit, and the biological sensor 12 itself or the configuration including the biological sensor 12 and the biological signal receiving unit 202 can also be grasped as an example of the biological signal acquiring unit. The biological signal receiving unit 202 outputs the received biological signal to the absorbance ratio calculation unit 204.

The attitude state signal receiving unit 203 receives or acquires attitude state signals output from various motion sensors 14 (in the example, the inertial sensor 14a and the geomagnetic sensor 14b), respectively. The posture state signal receiving unit 203 is an example of the posture state signal acquisition unit, and the configuration including the motion sensor 14 itself or the motion sensor 14 and the posture state signal receiving unit 203 is also grasped as an example of the posture state signal acquisition unit. Can be done. The attitude state signal receiving unit 203 outputs the received attitude state signal to the attitude state estimation unit 205.

The absorbance ratio calculation unit 204 calculates the absorbance ratio (R) to be used for calculating SpO2 based on the biological signal output from the biological signal receiving unit 202. The absorbance ratio calculation unit 204 outputs the calculated absorbance ratio (R) to the SpO2 calculation unit.

The absorbance ratio (R) is a value calculated by a known method utilizing the difference in absorption coefficients of oxidized hemoglobin (O ₂ Hb) and reduced hemoglobin (HHb) for light of different wavelengths. More specifically, the absorbance ratio (R) can be calculated by the following formula 1.
R = Red / IR = (AC _Red / DC _Red ) / (AC _IR / DC _IR )… Equation 1
However, Red is the absorbance of the received red light (that is, the first reflected light), and IR is the absorbance of the received infrared light (that is, the second reflected light). Further, AC _Red is the absorbance of the AC signal component (that is, the pulsating component) of the received red light Red, DC _Red is the absorbance of the DC signal component of the received red light Red, and AC _IR is the AC signal of the received infrared light IR. The absorbance of the component (that is, the pulsating component), DC _IR, is the absorbance of the DC signal component of the received infrared light IR.

The calculated absorbance ratio (R) is used for conversion to SpO2 according to the Beer-Lambert rule. SpO2 is represented by the following definition formula.

However, [O ₂ Hb] is the oxidized hemoglobin concentration, and [HHb] is the reduced hemoglobin concentration.
From this, SpO2 is calculated from the following theoretical formula in consideration of the Beer-Lambert law.

However, ε _{HHb and Red} are the molar extinction coefficient of red light Red with respect to reduced hemoglobin (HHb), ε _{O2Hb and Red} are the molar extinction coefficient of red light Red with respect to oxidized hemoglobin (O ₂ Hb), and ε _{O2Hb and IR} are hemoglobin oxide ( The molar extinction coefficient of infrared light IR with respect to O ₂ Hb) and ε _{HHb, IR} are the molar extinction coefficient of infrared light IR with respect to reduced hemoglobin (HHb).

By the way, it is known that the Beer-Lambert law has a large discrepancy between the theoretical formula and the experimental value. Therefore, conventionally, in the actual SpO2, SpO2 is calculated using a fixed parameter set linearly fitted to a region where SpO2 is 80 to 100%, for example, using the following formula and numerical value.
SpO2 = α _fix −β _fix × R… Equation 4
However, α _fix = 110 and β _fix = 25.

However, the above-mentioned fixed parameter set has been based on the premise that the subject is in the reference posture state and that the posture state has not changed (that is, it is in the resting state). Therefore, when the posture state of the subject is other than the reference posture state, SpO2 calculated by using the fixed parameter set is not always accurate. Therefore, the biological information measuring instrument 1 of the present disclosure calculates SpO2 by using a parameter set in consideration of the posture state instead of the fixed parameter set, as described later.

Still referring to FIG. 2, the posture state estimation unit 205 estimates the posture state of the subject based on the posture signal output from the posture state signal receiving unit 203. Postural states of the subject include, for example, the decubitus (supine and prone), sitting, and standing positions as well as the intermediate positions of these positions. In the present embodiment, the posture state estimation unit 205 estimates one of the three posture states of the lying position, the sitting position (reclining), and the standing position. As an example, when a posture signal indicating a horizontal direction (tilt angle (elevation angle) = 0 degree) is acquired from a motion sensor 14 mounted on the subject's chest, the posture state estimation unit 205 sets the subject's posture state in a lying position. Presumed to be in a state. As another example, when a posture signal indicating a vertical direction (tilt angle = 90 degrees) is acquired from a motion sensor 14 mounted on the subject's chest, the posture state estimation unit 205 sets the subject's posture state in a standing state. I presume. As yet another example, when a posture signal indicating an oblique direction (for example, tilt angle = 60 degrees) is acquired from a motion sensor 14 mounted on the chest of the subject, the posture state estimation unit 205 sets the posture state of the subject in a sitting position. Presumed to be in a state. Further, as described in other embodiments, the posture state estimation unit 205 may indicate the body position from the lying position to the standing position, for example, by an inclination angle. The posture state estimation unit 205 outputs the estimated posture state to the parameter set selection unit 207. As described in other embodiments, the posture state estimation unit 205 may estimate the posture state of the subject based on the biological signal obtained from the biological sensor 12.

The parameter set storage unit 206 stores preset parameter sets corresponding to each of the plurality of posture state models. The parameter set storage unit 206 can typically be formed as a storage area on the memory 24. The parameter set includes, but is not limited to, some parameters for calculating SpO2 from the absorbance ratio (R), such as α, β, and γ. In the present disclosure, the parameter set is expressed as "parameter set (α, β)" or "parameter set (α, β, γ)" as necessary. The parameter set may include, for example, a recumbent parameter set corresponding to the recumbent model, a sitting parameter set corresponding to the sitting model, and a standing parameter set corresponding to the standing model. I can't. In other words, these parameter sets are correction parameter sets for estimating SpO2 at the time of measurement in the reference posture state of the subject. The parameter set can be defined, for example, from data empirically obtained in clinical trials and the like.

The parameter set selection unit 207 selects and reads at least one parameter from the plurality of parameter sets stored in the parameter set storage unit 206 based on the posture state estimated by the posture state estimation unit 205. For example, when the posture state output from the posture state estimation unit 205 indicates the sitting position state, the parameter set selection unit 207 extracts the sitting position parameter set from the parameter set storage unit 206. The parameter set selection unit 207 outputs the selected and read parameter set to the SpO2 calculation unit 208.

The SpO2 calculation unit 208 calculates SpO2 based on the absorbance ratio (R) output from the absorbance ratio calculation unit 204 and the parameter set (α, β) output from the parameter set selection unit 207. Specifically, the SpO2 calculation unit 208 calculates SpO2 by applying the parameter set (α, β) to the absorbance ratio (R) according to the following formula.
SpO2 = α + β × R… Equation 5

That is, the parameter set (α, β) referred to here is composed of a value that considers the posture state of the subject, not a fixed value that does not consider the posture state as in the past. Therefore, by applying such a parameter set (α, β) to the absorbance ratio (R), SpO2 in the reference posture state, which is corrected for SpO2 in the posture state at the time of measurement, is calculated. become. The SpO2 calculation unit 208 outputs the calculated SpO2 to the measurement result storage unit 209.

The measurement result storage unit 209 stores SpO2 output from the SpO2 calculation unit 208 as a measurement result. The measurement result storage unit 209 can typically be formed as a storage area on the memory 24. The user can, for example, operate the user interface unit 30 to browse the measurement results stored in the measurement result storage unit 209.

As described above, according to the present embodiment, when measuring SpO2, the posture state of the subject is observed, the optimum parameter set according to the observed posture state is selected, and the selected parameter set is calculated as the absorptivity. Since SpO2 is calculated by applying it to the ratio, it is possible to calculate SpO2 in the reference posture state, which is corrected for SpO2 in the posture state at the time of measurement.

[Second Embodiment]
In the present embodiment, when measuring SpO2, the posture state of the subject is observed, the optimum parameter set is estimated from the preset parameter set according to the posture state estimated by the observation, and the estimated parameter set is calculated. A biometric information measuring instrument for calculating SpO2 and a measuring method using the biometric information measuring instrument will be described by applying the absorptivity ratio.

FIG. 3 is a block diagram showing an example of the configuration of the biological information measuring instrument according to the embodiment of the present invention. The biometric information measuring device 1 according to the present embodiment is different from the biometric information measuring device 1 according to the first embodiment in that a parameter set estimation unit 210 is provided instead of the parameter set selection unit 207. .. Further, the posture state estimation unit 205 of the present embodiment is configured to estimate the posture state based on the measured tilt angle, instead of selectively specifying the preset posture state.

That is, the posture state estimation unit 205 estimates and outputs the posture state based on the posture state signal output from the posture state signal receiving unit 203. For example, the posture state estimation unit 205 identifies the posture state by the inclination angle between the lying position and the sitting position or the inclination angle between the sitting position and the standing position based on the posture state signal. The posture state estimation unit 205 outputs the posture state indicated by the tilt angle to the parameter set estimation unit 210.

The parameter set estimation unit 210 estimates the optimum parameter set to be used for calculating SpO2 based on the tilt angle output from the posture state estimation unit 205. In the present embodiment, the parameter set estimation unit 210 is configured so that, for example, a parameter mixing ratio conversion map (hereinafter referred to as “mixing ratio conversion map”) as shown in FIG. 4A can be referred to. The parameter mixing ratio indicates the ratio (weight) of mixing the corresponding parameters in different parameter sets. The mixed ratio conversion map may be held in a predetermined storage area of the memory 24 with a predetermined data structure, or may be configured as a part of the parameter set estimation unit 210. The mixing ratio conversion map shown in FIG. 6A is exemplarily defined so that the mixing ratio changes linearly in relation to the inclination angle between the recumbent position and the sitting position. In another example, for example, as shown in FIG. (B), the mixing ratio conversion map is defined so that the mixing ratio changes non-linearly in relation to the tilt angle.

More specifically, the parameter set estimation unit 210 extracts one or more parameter sets from the parameter set storage unit 206 according to the tilt angle. For example, when the tilt angle is 30 degrees between the recumbent position and the sitting position, the parameter set estimation unit 210 extracts the recumbent position parameter set and the sitting position parameter set set adjacent to the tilt angle. Subsequently, the parameter set estimation unit 210 refers to the corresponding mixing ratio conversion map, determines the mixing ratio between the extracted parameter sets from the inclination angle, and calculates the parameter set according to the determined mixing ratio. For example, if the recumbent parameter sets are α _Lying and β _Lying , the recumbent parameter sets α _Sitting and β _Sitting , and the mixing ratio is 67:33, the parameter sets (α, β) are
α = α _Lying ×. 67 + α _Sitting ×. 33
β = β _Lying ×. 67 + β _Sitting ×. 33
Is calculated as.
The parameter set estimation unit 210 outputs the calculated parameter set to the SpO2 calculation unit 208 in the same manner as in the first embodiment.

The SpO2 calculation unit 208 is based on the absorbance ratio (R) output from the absorbance ratio calculation unit 204 and the parameter set (α, β) output from the parameter set selection unit 207, as in the first embodiment. To calculate SpO2.

As described above, according to the present embodiment, the posture state is estimated by the tilt angle based on the posture state signal, one or two or more parameter sets are extracted according to the estimated tilt angle, and the mixing ratio is obtained. The mixing ratio is determined from the tilt angle with reference to the conversion map, and the optimum parameter set is estimated or calculated using the determined mixing ratio. Therefore, more accurate SpO2 can be obtained regardless of the posture state of the subject. You will be able to calculate.

(Example 2-1)
In this example, for example, modeling of a non-linear mixing ratio conversion map as shown in FIG. 4B will be described. However, in this example, for the sake of simplification of the explanation, it is between the lying position and the standing position (however, the supine position to the standing position to the prone position (prone position), and the supine position to the standing position and the standing position to the lying position). Consider an estimation model of the standing position. The parameter set estimation unit 210 estimates the optimum parameter set by using one or more parameter sets according to the estimation model described here.

First, it is assumed that the body composition of the subject in each posture state has its certainty in a form that follows a normal distribution, and as shown in FIG. 5, this certainty exists so as to overlap in each posture state. I think. Further, it is assumed that each parameter set follows a normal distribution with a mean μ = n and a variance σ = 1/2, and a case where two distributions of a lying position and a standing position exist is considered.

Now, assuming that the function that follows the lying parameter set distribution is f (x) and the function that follows the standing parameter set distribution is g (x), they are expressed as follows.

When considering the optimum parameter set when the tilt angle x = 0 (rad) with reference to FIG. 5, only the recumbent parameter set may be selected because of the completely lying posture state. However, this example introduces the concept of mixture distribution. That is, the overlap of the distributions of f (x) and g (x) when x = 0 is considered. Specifically, f (0) and g (0) are

Therefore, f (0): g (0) is

Will be. That is, the optimum parameter set when the inclination angle x = 0 is a value obtained by mixing the recumbent parameter set at a ratio of 92% and the standing parameter set at a ratio of 8%.

Similarly, based on the tilt angle x, the mixture ratio of different parameter sets is determined using the mixture distribution function, which calculates the optimum parameter set. For example, when the inclination angle x = 6 / π, the mixing ratio of the optimum parameter set is 69% for the recumbent parameter set and 31% for the standing parameter set.

If it is desired to assume that the mixing ratio when the inclination angle x = 0 is more biased toward the recumbent position, the mixing ratio can be arbitrarily adjusted by setting the variance σ to be small.

The mixing ratio calculated as described above (for example, the recumbent parameter set = 69%, the standing parameter set = 31%) is the probability of occurrence of a two-mixed normal distribution with the same weight, as shown in FIG. It can also be considered as the contribution ratio of each normal distribution f (x) / 2, g (x) / 2 in (f (x) + g (x))) / 2.

This can also extend the number of distributions in the parameter set to N.

As described above, by considering the distribution of the parameter set, it is possible to model a non-linear mixing ratio conversion map as shown in FIG. 4B, for example. As a result, the parameter set estimation unit 210 estimates the optimum parameter set with reference to such a mixing ratio conversion map.

In this embodiment, an example using a normal distribution has been described, but the present invention is not limited to this, and other distributions such as a gamma distribution and a Poisson distribution may be used.

(Example 2-2)
In this example, the case where the mixture distribution of the above parameter set is expanded into multiple variables will be described.

That is, the distribution functions f (x, y) and g (x, x, calculated using the tilt angle of the subject's posture state as multiple variables in the vertical direction (pitch angle) x and the horizontal direction (roll angle) y are used. The mixing ratio of the recumbent parameter set and the standing parameter set based on y) is defined as follows.
Mixing ratio of recumbent parameter set = f (x, y) / (f (x, y) + g (x, y))
Mixing ratio of standing parameter set = g (x, y) / (f (x, y) + g (x, y))
However,

Is. However, in this example, g (x, y) is defined as a distribution having a larger variance in the y-axis direction than f (x, y).

As described above, the mixing ratio of each parameter set is determined according to the value of the inclination angle (x, y). Therefore, the parameter set estimation unit 210 determines a more realistic mixing ratio from the tilt angle (x, y) specified based on the posture state signal detected by the motion sensor 14, for example, and determines the determined mixing ratio. Since the optimum parameter set is estimated or calculated by using the method, more accurate SpO2 can be calculated regardless of the posture state of the subject.

(Example 2-3)
Modeling of the nonlinear mixture ratio conversion map is also realized by using nonlinear functions based on various n-th order polynomials instead of the above mixture distribution function. As an example, f (x) is represented by the following non-linear function.

As another example, f (x) is

It may be. As yet another example, f (x) is
f (x) = 0.9288x ³ -2.2928x ² +0.673x + 1.0043 ... Equation 17
It may be.

Further, as described above, the distribution of the parameter set based on the nonlinear function may be expanded into multiple variables. That is, the nonlinear function when the calculated tilt angle (x, y) is used can be defined as follows in this example.
f (x, y) = 0.9288x ³ -2.2928x ² + 0.673x + 1.43-y ² ... Equation 18

[Third Embodiment]
In this embodiment, SpO2 is based on the absorptivity ratio (R) calculated based on the detected biological signal and the parameter set (α ₁ , β ₁ ) corresponding to the posture state estimated according to the posture state signal. In the case where is calculated, for example, a biological information measuring instrument for estimating a parameter set (α ₂ , β ₂ ) when changing to another posture state in a short period of time and a measuring method using the same will be described. That is, the present embodiment utilizes the characteristic that the SpO2 value does not change or changes very little immediately before and after the change in the posture state of the subject.

FIG. 7 is a block diagram showing an example of the configuration of the biological information measuring instrument according to the embodiment of the present invention. The biological information measuring instrument 1 according to the present embodiment is configured so that the parameter set estimation unit 210 can newly estimate the parameter set based on the SpO2 calculated by the SpO2 calculation unit 208. It is different from the embodiment. The functions and / or configurations of the other components in the figure are the same as those described above, and thus the description thereof will be omitted. In the following description, it is assumed that the parameter set storage unit 206 stores, for example, the sitting parameter set (α _Sitting , β _Sitting ).

For example, the posture state estimation unit 205 estimated that the posture state of the subject was the sitting position (tilt angle = 60 degrees) based on the detected posture signal, but the posture state of the subject changed, and this Therefore, it is estimated that the reclining (tilt angle = 30 degrees). Since the parameter set selection unit 207 cannot extract the parameter set in the case of reclining from the parameter set storage unit 206, the parameter set estimation unit 210 is requested to estimate the parameter set in the case of reclining.

In response to this, when the parameter set estimation unit 210 is given a new posture state (that is, tilt angle = 30 degrees) from the posture state estimation unit 205, for example, the parameter set storage unit 206 corresponds to the immediately preceding posture state. Based on the SpO2 value calculated when the posture state stored in the measurement result storage unit 209 is the sitting state and the biological signal detected by the absorptiometry ratio calculation unit 204, while extracting the sitting position parameter set. Obtain the calculated absorbance ratio. Subsequently, the parameter set estimation unit 210 estimates the parameter set (α _Reclining , β _Reclining ) when the posture state is reclining, based on the sitting parameter set, the SpO2 value, and the absorbance ratio. That is, in the present embodiment, it is assumed that the SpO2 value does not change or is small before and after the change in the posture state immediately after the change in the posture state (for example, several seconds to several minutes). As another example, the parameter set estimation unit 210 estimates a new parameter set based on the above-mentioned sitting parameter set, SpO2 value, and absorbance ratio, and further based on the absorbance ratio calculated in the immediately preceding posture state. Is also good. In this case, for example, the parameter set estimation unit 210 may be configured to receive the absorbance ratio and the attitude state in time series from the absorbance ratio calculation unit 204 and the attitude state estimation unit 205, respectively. The parameter set estimation unit 210 stores the newly estimated parameter set as a reclining parameter set in the parameter set storage unit 206.

As a result, for example, when the parameter sets of the lying position, the sitting position, and the standing position are prepared in advance in the parameter set storage unit 206, the posture state of the subject changes to a state other than these during the measurement of SpO2. Even so, it is possible to estimate the parameter set and add the estimated new parameter set to the parameter set storage unit 206 at any time so that the parameter sets in various posture states can be accumulated. Become.

[Fourth Embodiment]
In the present embodiment, a biometric information measuring instrument that calculates SpO2 and a parameter set (α _fix , β _fix , γ) obtained by adding a new correction parameter γ to the conventional fixed parameter set (α _fix , β _fix ) and A measurement method using this will be described. Here, γ is a function according to the posture state and the absorbance ratio R.

It is a block diagram which shows an example of the structure of the biological information measuring instrument which concerns on one Embodiment of this invention. The biological information measuring device 1 shown in the figure is the above-described embodiment in that the parameter set selection unit 207 receives the posture state estimated from the posture state estimation unit 205 and also receives the absorbance ratio from the absorbance ratio calculation unit 204. It is different from the configuration in.

For example, if the posture state estimation unit 205 estimates that the posture state is the lying position based on the detected posture state signal, the parameter set selection unit 207 is the lying state corresponding to the lying state and the absorbance ratio. A parameter set (α _fix , β _fix , γ _Lying ) including the position parameter γ _Lying is selected, and this is output to the SpO2 calculation unit 208. Alternatively, the parameter set selection unit 207 selects the recumbent position parameter γ _Lying corresponding to the recumbent state and the absorbance ratio, and combines this with the fixed parameter set (α _fix , β _fix ) to create a new parameter set (α _fix). , Β _fix , γ _Lying ).

Subsequently, the SpO2 calculation unit 208 of the present embodiment calculates SpO2 using the following formula.
SpO2 = α _fix + β _fix × R + γ… Equation 19
However, α- _fix and β- _fix are conventional fixed values (for example, α- _fix = 110, β- _fix = 25) linearly fitted to the region where the oxygen saturation in arterial blood is 80 to 100%, and γ is the posture state. It is a correction parameter according to the absorbance ratio and the like.
As a result, the SpO2 calculation unit 208 calculates SpO2 according to the above formula based on the absorbance ratio (R) based on the detected biological signal and the selected parameter set (α _fix , β _fix , γ _Lying ).

Further, as shown in the second embodiment, the biological information measuring device 1 may be configured by the parameter set estimation unit 210 instead of the parameter set selection unit 207. That is, the parameter set estimation unit 210 selects one or two or more parameters γ according to the estimated posture state, estimates the optimum parameter γ from these parameters γ, and sets a parameter set based on the parameter γ (α _fix , β _fix , γ) may be output to SpO2.

[Fifth Embodiment]
In the present embodiment, the biological information measurement for estimating the correction parameter γ in consideration of the characteristic that the SpO2 value does not change or changes very little immediately after the change in the posture state of the subject before and after the change. The vessel and the measurement method using the vessel will be described.

For example, it is assumed that the parameter set estimation unit 210 as shown in FIG. 7 is given a lying position (tilt angle = 0 degrees) as a posture state. The parameter set estimation unit 210 detects, for example, the SpO2 value calculated when the posture state stored in the measurement result storage unit 209 is the recumbent state, the fixed parameter set (α _fix , β _fix ), and the detection. Based on the absorbance ratio (R) calculated based on the obtained biological signal, the parameter γ when the posture state is the sitting state is estimated.

[Sixth Embodiment]
In the present embodiment, the posture state is estimated by using the biological signal obtained from the biological sensor 12 in addition to the posture state signal obtained from the motion sensor 14, and the optimum parameter set corresponding to the estimated posture state is selected. Alternatively, a biological information measuring device to be estimated and a measuring method using the same will be described.

That is, when the biological signal receiving unit 202 receives the biological signal output from the biological sensor 12, it outputs it to the absorbance ratio calculation unit 204 and the posture state estimation unit 205, respectively. Further, when the posture state signal receiving unit 203 receives the posture state signal output from the motion sensor 14, the posture state signal receiving unit 203 outputs the posture state signal to each of the posture state estimation units 205. From this, the posture state estimation unit 205 estimates the posture state of the subject based on the biological signal and the posture state signal.

As described above, the posture state of the subject can generally be estimated using the posture state signal obtained by the motion sensor 14, but when comparing the standing position and the sitting position, for example, which of the posture state signals obtained from the inertial sensor is used alone. It is difficult to estimate whether it is in a postural state. On the other hand, the present inventors have confirmed that the biological signal detected by the biological sensor 12 differs depending on the posture state of the subject. Therefore, for example, the posture state estimation unit 205 provisionally estimates the posture state of the subject based on the posture state signal, and finally estimates the posture state based on the biological signal for the provisionally estimated posture state. It is configured to do.

As described above, according to the present embodiment, the posture state estimation unit 205 estimates the posture state by using the biological signal obtained from the biological sensor 12 in addition to the posture state signal obtained from the motion sensor 14. , A more accurate posture state will be obtained, and therefore the parameter set selected will also be more accurate.

Each of the above embodiments is an example for explaining the present invention, and the present invention is not intended to be limited only to these embodiments. The present invention can be implemented in various forms as long as it does not deviate from the gist thereof.

For example, in the above embodiment, the parameter set (α, β, γ) including the parameters α, β, and γ has been described, but the present invention is not limited to these parameters. For example, since the tendency of noise included in the biological signal changes according to the posture state of the subject, a parameter set including parameters considering such noise may be used.

Further, for example, in the method disclosed in the present specification, steps, operations or functions may be performed in parallel or in a different order as long as the results are not inconsistent. The steps, actions and functions described are provided by way of example only, and some of the steps, actions and functions can be omitted and combined with each other to the extent that they do not deviate from the gist of the invention. It may be one, or other steps, actions or functions may be added.

In addition, although various embodiments are disclosed in the present specification, specific features (technical matters) in one embodiment are added to other embodiments or other embodiments while being appropriately improved. It can be replaced with specific features in embodiments, such embodiments are also included in the gist of the invention.

1 ... Biometric information measuring device 10 ... Sensor unit 12 ... Biological sensor 12a ... PPG sensor 14 ... Motion sensor 14a ... Inertial sensor 14b ... Geomagnetic sensor 20 ... Control unit 201 ... Sensor control unit 202 ... Biometric signal receiving unit 203 ... Attitude state signal Reception unit 204 ... Absorption ratio calculation unit 205 ... Attitude state estimation unit 206 ... Parameter set storage unit 207 ... Parameter set selection unit 208 ... SpO2 calculation unit 209 ... Measurement result storage unit 210 ... Parameter set estimation unit 30 ... User interface unit 40 ... Communication interface section

Claims (11)

1. A biological signal acquisition unit that acquires the biological signal of the subject output from the biological sensor including the PPG sensor,
   A posture state signal acquisition unit that acquires the posture state signal of the subject output from the motion sensor, and
   A posture state estimation unit that estimates the posture state of the subject based on the posture state signal acquired by the posture state signal acquisition unit, and a posture state estimation unit.
   A SpO2 calculation unit that calculates SpO2 in the reference posture state of the subject based on the biological signal acquired by the biological signal acquisition unit and the posture state estimated by the posture state estimation unit is provided.
   The SpO2 calculation unit calculates the SpO2 by applying a parameter set according to the estimated posture state to the absorbance ratio calculated based on the acquired biological signal.
   Biological information measuring instrument.
2. A parameter set storage unit for storing a plurality of parameter sets corresponding to a plurality of posture state models is further provided.
   The biometric information measuring device according to claim 1.
3. A parameter set selection unit for selecting one of the parameter sets corresponding to the estimated posture state from the parameter set storage unit is further provided.
   The SpO2 calculation unit corrects the absorbance ratio based on the selected predetermined parameter set.
   The biometric information measuring device according to claim 2.
4. One or two or more of the parameter sets corresponding to the estimated posture state are selected from the parameter set storage unit, and one parameter set is estimated by interpolation calculation based on the selected one or more parameter sets. Further equipped with a parameter set estimation unit
   The SpO2 calculation unit corrects the absorbance ratio based on the estimated one parameter set.
   The biometric information measuring device according to claim 2.
5. The SpO2 calculation unit corrects the absorbance ratio by the interpolation calculation using the probability density function.
   The biometric information measuring device according to claim 4.
6. The SpO2 calculation unit corrects the absorbance ratio by the interpolation calculation using a predetermined nonlinear function.
   The biometric information measuring device according to claim 4.
7. Further, a parameter set estimation unit for estimating a parameter set corresponding to a specific posture state and the absorbance ratio based on the estimated posture state is provided.
   The parameter set estimation unit stores the estimated parameter set in the parameter set storage unit.
   The biometric information measuring device according to claim 2.
8. The posture state estimation unit estimates the posture state of the subject based on the biological signal output from at least one biological sensor.
   The biometric information measuring device according to claim 1.
9. The biometric information measuring device according to claim 8, wherein the at least one biosensor includes at least one of a blood pressure sensor, an ECG sensor, and an electromyographic sensor.
10. The motion sensor includes at least one of a gravity sensor, an acceleration sensor, a gyro sensor, a geomagnetic sensor, a pressure sensitive sensor, an ultrasonic sensor, an infrared sensor, an image sensor, and a spectrum sensor.
    The biometric information measuring device according to claim 1.
11. Acquiring the biological signal of the subject output from the biological sensor,
    Acquiring the posture state signal of the subject output from the motion sensor,
    To estimate the posture state of the subject based on the acquired posture state signal,
    Includes calculating SpO2 of the subject in the reference posture state based on the acquired biological signal and the estimated posture state.
    Calculating the SpO2 includes calculating the SpO2 by applying a parameter set according to the estimated posture state to the absorbance ratio calculated based on the acquired biological signal. ,
    Biological information measurement method.

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