JP5927843B2 - Congestion determination device, pulse wave measurement device, and congestion determination method - Google Patents

Description

  The present invention relates to a congestion determination apparatus, a pulse wave measurement apparatus, and a congestion determination method.

  Patent Document 1 listed below discloses a pressure pulse wave sensor that measures an internal pressure waveform by applying a constant pressure to a part for measuring a pulse wave. The pressure pulse wave sensor is mounted so that a non-pressing region is formed between the living body part around the pressure pulse wave sensor and the pressure pulse wave sensor in order to secure a venous blood return path.

JP 2002-224064 A

For example, when a pulse wave sensor is fixed by wrapping a belt around a measurement site such as an arm, a non-pressing region is provided as in Patent Document 1 to provide a congested state (hereinafter referred to as a congested state). Can be prevented. However, when the measurement subject hangs his arm downward for a long time, the vicinity of the measurement site becomes congested and adversely affects the measurement of the pulse wave.
The present invention provides a technique for determining whether or not a measurement site is congested.

The blood congestion determination apparatus according to the present invention includes: a first acquisition unit that acquires a physical quantity of a mounting part that is attached to a living body or a measurement part that measures a pulse wave of the living body; and light irradiated to the measurement part is the measurement part in a second obtaining means for obtaining a measurement signal based on reflected light intensity, the conditions predetermined with respect to tilt with respect to the direction of gravity of said mounting portion of the posture in accordance with the prior Symbol physical quantity obtained by the first obtaining means, A state in which the variation range of the posture is within a predetermined range and the variation range of the measurement signal acquired by the second acquisition unit is within a predetermined range continues for a certain period of time. In this case, it is characterized in that it comprises determination means for determining that the measurement site is congested. According to this configuration, it can be determined whether or not the measurement site is congested.

Moreover, the congestion determination apparatus according to the present invention may be configured such that, in the congestion determination apparatus, the first acquisition unit acquires an acceleration according to a posture and a movement of the wearing part or the measurement part as the physical quantity.
In addition, the blood congestion determination apparatus according to the present invention includes a first acquisition unit that acquires acceleration according to the posture and movement of a wearing part that is attached to a living body or a measurement part that measures a pulse wave of the living body, and the measurement part. A second acquisition unit configured to acquire a measurement signal based on the amount of light reflected by the measurement site, and a posture in which the posture of the measurement site based on the acceleration acquired by the first acquisition unit is inclined in the direction of gravity. The fluctuation range of the acceleration is within a predetermined range, and the fluctuation range of the amplitude of the measurement signal with respect to the reference signal indicating the measurement result of the pulse wave in the non-congested state is predetermined. Determination means for determining that the measurement site is congested when satisfying each condition of being in a range and satisfying the condition that the condition satisfying each condition continues for a certain period of time It is characterized in. According to this configuration, it can be accurately determined whether or not the measurement site is congested.

In the blood congestion determination apparatus according to the present invention, the predetermined range for the fluctuation range of the acceleration may be a range determined according to a pulse wave measurement target.
According to this configuration, it is possible to make a determination suitable for a living body that is a pulse wave measurement target.

  A pulse wave measurement device according to the present invention is attached to any one of the above-mentioned blood congestion determination devices and a measurement site for measuring a pulse wave, irradiates the measurement site with light, and the irradiated light passes through the measurement site. Alternatively, a light emitting / receiving unit that outputs a measurement signal based on the amount of received light to the blood congestion determination device, and a pulse wave signal indicating the pulse wave of the living body based on the determination result in the blood congestion determination device and the measurement signal. Output means for outputting. According to this configuration, it is possible to output a pulse wave signal corresponding to the blood congestion state.

In the method for determining congestion according to the present invention, the first acquisition unit acquires a physical quantity of a mounting site to be mounted on a living body or a measurement site for measuring a pulse wave of the living body, and a second acquiring unit acquires the measurement site. irradiation light acquires a measurement signal based on the amount of light reflected by the measurement site, judging means, with respect to the direction of gravity in the attitude of the installation position in accordance with the prior Symbol physical quantity obtained by said first obtaining means Predetermined conditions regarding the inclination, the fluctuation range of the posture is within a predetermined range, and the fluctuation range of the measurement signal acquired by the second acquisition unit is within a predetermined range. when a filled state has continued for a predetermined time, the measurement site is characterized that you determined is congestive state. In the method for determining blood congestion according to the present invention, the first acquisition unit acquires the acceleration corresponding to the posture and movement of the attachment part to be attached to the living body or the measurement part for measuring the pulse wave of the living body, and obtains the second acquisition. The means acquires a measurement signal based on the amount of light reflected on the measurement site by the light irradiated on the measurement site, and the determination unit determines the posture of the measurement site based on the acceleration acquired by the first acquisition unit. The posture is tilted in the direction of gravity, the fluctuation range of the acceleration is within a predetermined range, and the fluctuation of the amplitude of the measurement signal with respect to the reference signal indicating the measurement result of the pulse wave in a non-congested state When the condition that the width is within a predetermined range is satisfied and the condition that the condition is satisfied for a certain period of time is satisfied, the measurement site is determined to be congested To do And features. According to this configuration, it can be determined whether or not the measurement site is congested.

It is a figure showing the external appearance of the pulse-wave measuring apparatus which concerns on embodiment. It is a block diagram which shows the structural example of the pulse-wave measuring apparatus which concerns on embodiment. It is a figure showing the functional block of the control part in embodiment. It is a figure explaining the attitude | position of the mounting site | part in embodiment. It is an operation | movement flowchart showing the whole operation | movement of the pulse-wave measuring apparatus which concerns on embodiment. It is an operation | movement flowchart of the determination process A in embodiment. It is an operation | movement flowchart of the determination process B in embodiment. (A) is a figure which shows the example of a waveform of an acceleration signal. (B) is a figure which shows the waveform of the movement standard deviation based on the acceleration signal of (a). (A) is a figure which shows the example of a waveform of the measurement signal of a pulse wave. (B) is a figure which shows the waveform of the movement standard deviation based on the measurement signal of (a).

<Configuration>
FIG. 1 is a diagram illustrating an appearance of a pulse wave measurement device according to the present embodiment. FIG. 1A is a view of the pulse wave measuring device 1 as viewed from above. The pulse wave measuring device 1 is configured by connecting a device main body 10 attached to a wrist of a living body 2 and a pulse wave sensor 20 attached to a measurement site for measuring a pulse wave by a cable 30. In the present embodiment, the pulse wave sensor 20 is fixed to the palm side of the base of the index finger by a band 40 as shown in FIG.

  The apparatus main body 10 is provided with an operation switch 16 for operating the display 15 and the pulse wave measuring apparatus 1. In addition, the apparatus main body 10 includes a triaxial acceleration sensor 17. The acceleration sensor 17 is provided so that the directions of the three axes for detecting acceleration coincide with the XYZ axes in FIG. 1A, and detects the acceleration in the XYZ axis directions caused by the force applied to the acceleration sensor 17. Specifically, in FIG. 1A, the left-right direction of the apparatus body 10 (the direction in which the hand extends) corresponds to the X axis, and the up-down direction of the apparatus body 10 (the width direction of the wrist) corresponds to the Y axis. The direction perpendicular to the paper plane perpendicular to the XY axis (the direction from the display 15 of the apparatus main body 10 toward the wrist) corresponds to the Z axis. In this embodiment, the apparatus main body 10 functions as a blood congestion determination apparatus of the present invention, and the wrist to which the apparatus main body 10 is attached corresponds to the attachment site. Hereinafter, each component of the pulse wave measuring device 1 will be described in the order of the pulse wave sensor 20 and the device main body 10.

  FIG. 2 is a block diagram showing the configuration of the pulse wave measuring device 1. The pulse wave sensor 20 includes a light emitting / receiving unit 210 and a driving unit 220. The light emitting / receiving unit 210 includes, for example, a light emitting element such as an LED (Light Emitting Diode) that emits light having a wavelength of blue light, and a light receiving element such as a photodiode that receives light of blue light. The drive unit 220 is supplied with a control signal for controlling the light emission intensity and the light emission timing of the light emitting element from an analog control circuit (not shown), and receives a current having a magnitude corresponding to the amplitude of the control signal. To supply.

  In FIG. 1B, a portion of the pulse wave sensor 20 that is in contact with the measurement site (finger) is provided with a transmission plate (not shown) that transmits light, such as a glass plate, below the transmission plate. A light emitting / receiving unit 210 is provided. The light emitting element of the light receiving / emitting unit 210 is fixed so that the direction of the transmission plate is the optical axis direction, and the light receiving element of the light receiving / emitting unit 210 is fixed so that the light receiving surface faces the direction of the transmission plate. The light emitted from the light emitting element is transmitted through the transmission plate and irradiated to the measurement site, and the light receiving element receives the light reflected from the measurement site through the transmission plate. The light receiving element transmits a current measurement signal having a magnitude corresponding to the amount of received light to the apparatus main body 10 via the cable 30.

  The blood vessel at the measurement site repeats expansion and contraction in the same cycle as the heartbeat, and the amount of light emitted from the light emitting element increases and decreases at the same cycle as the blood vessel expansion and contraction, and is reflected according to the increase and decrease. The light intensity changes. Therefore, the current flowing through the light receiving element has a component indicating a change in the volume of the blood vessel at the measurement site.

  The apparatus main body 10 includes a control unit 110, a signal processing unit 120, a timing unit 130, a clock supply unit 140, a display unit 150, an operation unit 160, an attitude detection unit 170, and a storage unit 180. The control unit 110 includes a CPU (Central Processing Unit) and a memory (ROM (Read Only Memory) and RAM (Random Access Memory)), and the CPU executes a control program stored in the ROM, thereby the control unit 110. Control each part connected to the. Specifically, the control unit 110 performs a determination process for determining whether or not the measurement site is congested and an output process for outputting a pulse wave signal corresponding to the state of the measurement site. Details of the function of the control unit 110 will be described later.

  The signal processing unit 120 includes a first signal processing unit 120a (FIG. 3) and a second signal processing unit 120b (FIG. 3). The first signal processing unit 120a functions as a first acquisition unit. The first signal processing unit 120a obtains and amplifies the measurement signal output from the light emitting / receiving unit 210 of the pulse wave sensor 20, and quantizes the amplified signal at a predetermined sampling frequency. And an A / D conversion circuit (not shown). The second signal processing unit 120b functions as a second acquisition unit. The second signal processing unit 120b obtains a signal indicating acceleration (hereinafter referred to as an acceleration signal) output from an acceleration sensor 17 (to be described later) and quantizes it at a predetermined sampling frequency (illustrated). Abbreviation). In the present embodiment, acceleration is an example of a physical quantity of the present invention.

  The clock unit 130 counts the clock signal from the clock supply unit 140 and clocks the time. The clock supply unit 140 includes an oscillation circuit and a frequency dividing circuit. The clock supply unit 140 supplies a reference clock signal to the control unit 110 by the oscillation circuit, and generates a time measuring clock signal for time measurement by the frequency dividing circuit to the control unit 110. Supply. The display unit 150 includes a display 15, and displays various images such as time information measured by the time measuring unit 130, a menu screen for measuring pulse waves, and measurement results under the control of the control unit 110. The operation unit 160 includes an operation switch 16 and sends an operation signal indicating that the operation switch 16 has been operated to the control unit 110. The posture detection unit 170 includes an acceleration sensor 17 and outputs an acceleration signal indicating the acceleration in each axial direction detected by the acceleration sensor 17. The storage unit 180 stores various data such as threshold data and waveform data used for determination processing described later.

  Next, functions of the control unit 110 will be described. FIG. 3 is a diagram illustrating a functional block for realizing the functions of determination processing and output processing in the control unit 110 and another part of the configuration. The control unit 110 includes a determination unit 111 and a pulse wave output unit 112. The determination unit 111 functions as a determination unit. Based on the data (hereinafter referred to as acceleration data) obtained by A / D conversion of the acceleration signal by the second signal processing unit 120b, the determination unit 111 is in a resting state (a state in which body movement is hardly received). A determination (hereinafter referred to as a first determination) and a determination (hereinafter referred to as a second determination) of whether or not the measurement site is prone to congestion (whether the mounting site is tilted in the direction of gravity). And determining whether or not the change in the volume of the blood vessel at the measurement site is greater than or equal to a certain amount based on each data obtained by A / D conversion of the measurement signal from the first signal processing unit 120a (hereinafter referred to as measurement data) (Referred to as third determination). Hereinafter, each determination will be described.

  In the first determination, it is determined whether or not the wearing site is in a resting state based on the first determination condition. The first determination condition is that the acceleration fluctuation range calculated based on the acceleration data is equal to or less than the threshold value in the storage unit 180. The determination unit 111 determines that the subject is resting when the first determination condition is satisfied. In this embodiment, the fluctuation range of acceleration uses the moving standard deviation for the acceleration data in each axis direction, but is not limited to this as long as it is an index representing the displacement of acceleration, such as a moving average value for the acceleration in each axis direction. Absent.

In the second determination, it is determined whether or not the posture is likely to cause congestion based on the second determination condition. Here, the relationship between the attitude | position of a mounting site | part and the acceleration of each axial direction is demonstrated. 4A and 4B show a state in which the measurement subject A stands in the direction of the arrow P. In this figure, the XYZ axes indicate the directions of the detection axes of the acceleration sensor 17 in the apparatus main body 10 as in FIG. 4A shows a state in which the measurement subject A is leveling the mounting part a of the apparatus body 10, and FIG. 4B shows a state in which the measurement target A lowers his arm and places the mounting part a in the direction of gravity. It is in a state tilted to.
In the state of FIG. 4A, the acceleration sensor 17 is applied with gravity G in the Z-axis direction, and the detected acceleration components (ax, ay, az) of the XYZ axes are ax = 0 m / s ² , ay = 0 m / s ² and az = 9.8 m / s ² . In the posture of FIG. 4B, the acceleration sensor 17 applies gravitational acceleration in the X-axis direction, and the detected acceleration components (ax, ay, az) of the XYZ axes are ax = 9.8 m / s ² , ay = 0 m / s ² and az = 0 m / s ² . As described above, when the mounting site is tilted in the direction of gravity, the acceleration component in the X-axis direction is a value corresponding to the gravitational acceleration. As shown in FIG. 4B, in a posture in which the mounting site a is tilted in the direction of gravity, blood is difficult to return from the fingertip toward the upper arm. Therefore, the second determination condition is that the acceleration data in the X-axis direction has a value corresponding to the gravity direction, and the determination unit 111 is in a posture in which the measurement site is easily congested when the second determination condition is satisfied. It is determined that

  In the third determination, it is determined whether or not the change in the volume of the blood vessel at the measurement site is greater than or equal to a certain level based on the third determination condition. The third determination condition is that the fluctuation range of the measurement signal calculated from the measurement data is not more than the threshold value in the storage unit 180. In this embodiment, the fluctuation range of the measurement signal is a measurement signal with respect to the amplitude of the measurement signal (hereinafter referred to as a reference signal) when the pulse wave is measured in a posture in which the wearing site is horizontal and almost no body movement is received. Is the amplitude ratio. The storage unit 180 stores waveform data of the reference signal in advance. The determination unit 111 determines that the change in the volume of the blood vessel at the measurement site is not a certain level or more when the third determination condition is satisfied. As described above, the blood vessel in the measurement site repeatedly expands and contracts in the same cycle as the heartbeat, and the measurement signal includes a component of the volume change of the blood vessel. When blood is congested, the volume of venous blood vessels at the measurement site increases because venous blood increases. Compared with the case where it is not, the amount of change in the volume of the blood vessel at the measurement site is also reduced. As a result, when the blood is congested, the amplitude of the measurement signal is smaller than when the blood is not congested. Note that the fluctuation range of the measurement signal may be an index that represents a change in the amplitude of the measurement signal, such as a moving standard deviation or a moving average value of the measurement signal.

  When the determination unit 111 satisfies all of the first determination condition, the second determination condition, and the third determination condition, the timing unit 130 starts measuring time, and the state that satisfies each determination condition continues for a certain period of time. It is determined that the measurement site is congested in (fourth determination condition).

  The pulse wave output unit 112 includes an adaptive filter processing unit 112a and an analysis unit 112b. The adaptive filter processing unit 112a passes the measurement data output from the first signal processing unit 120a and the acceleration data output from the second signal processing unit 120b through the adaptive filter in the case of a congested state, thereby detecting body motion noise. The result is output to the analysis unit 112b, and in the non-congested state, the measurement data signal output from the first signal processing unit 120a is output to the analysis unit 112b as a pulse wave signal.

The adaptive filter that removes body motion noise may use a known adaptive algorithm such as an LMS (Least Mean Square) algorithm using pulse wave data as an input signal and acceleration data as a learning signal. The acceleration data serving as a learning signal for the body motion removal algorithm is obtained by combining the acceleration data (ax, ay, az) based on the acceleration signal detected by the acceleration sensor 17 with a combined acceleration a = (ax ² + ay ² + az ² ) ^1/2. It may be the result of obtaining. In addition, the adaptive filter is used twice, the first time using the X-axis acceleration component as the learning signal, and the second time using the output from which the X-axis acceleration component is removed as the input signal, and the Y-axis acceleration component. May be used as a learning signal.

  The analysis unit 112b calculates a pulse interval and a pulse rate from the pulse wave signal from which body motion noise has been output that is output to the adaptive filter unit 112a. Specifically, the analysis unit 112b calculates the FFT for each predetermined time in the waveform of the pulse signal, and sets the frequency having the strongest spectral power as the frequency of the pulse wave within the predetermined time. Further, information indicating the average pulse interval within a predetermined time is output to the display unit 150 with the reciprocal of the frequency.

<Operation example>
Hereinafter, an operation example of the pulse wave measuring apparatus 1 according to the present embodiment will be described. FIG. 5 is a diagram showing an operation flow of the pulse wave measuring apparatus 1. When the control unit 110 of the pulse wave measuring apparatus 1 accepts an operation for measuring a pulse wave via the operation unit 160 (step S10: YES), the pulse wave sensor 20 irradiates the measurement site with light, and the measurement site receives the light. The reflected light is received and output of the measurement signal corresponding to the amount of received light is started, and the acceleration sensor 17 detects acceleration at the attachment site of the apparatus body 10 and starts output of the acceleration signal (step S11). . If control unit 110 does not accept an operation for measuring a pulse wave via operation unit 160 (step S10: NO), control unit 110 waits until the operation is performed.

  When the measurement signal and the acceleration signal are output from the pulse wave sensor 20 and the acceleration sensor 17, the control unit 110 starts the determination process A including the first determination, the second determination, and the third determination (step S12). Here, the operation flow of the determination process A is shown in FIG. The controller 110 first makes a first determination. Specifically, the control unit 110 performs A / D conversion on the acceleration signal output from the acceleration sensor 17 in the second signal processing unit 120b, and acquires time-series acceleration data (ax, ay, az). The movement standard deviation is stored in the RAM and the acceleration data in each axial direction is calculated as a fluctuation range of the acceleration every predetermined time (for example, every 3 seconds) (step S201). And the control part 110 determines with being a resting state, when the movement standard deviation of the acceleration of each axial direction is below the threshold value memorize | stored in the memory | storage part 180 (step S202: YES), and step S203 of FIG. The process proceeds to the second determination process.

  When the acceleration data ax in the X-axis direction is a value corresponding to the gravitational acceleration among the acceleration data, the control unit 110 determines that the posture is likely to cause congestion (step S203: YES). 3 The process proceeds to the determination process. Specifically, the control unit 110 performs A / D conversion on the measurement signal output from the pulse wave sensor 20 in the first signal processing unit 120a, and acquires each time-series measurement data from the first signal processing unit 120a. Stored in the RAM. Then, the control unit 110 obtains the amplitude of the measurement signal based on the measurement data, and uses the waveform data of the reference signal in the storage unit 180 to calculate the ratio of the amplitude of the measurement signal to the amplitude of the reference signal. The width is calculated (step S204). Then, when the ratio of the amplitude of the measurement signal to the amplitude of the reference signal is equal to or less than the threshold (1/3 to 1/4) (step S205: YES), the control unit 110 has a constant change in the volume of the blood vessel at the measurement site. It is determined that it is not above. In addition, when a negative determination is made in step S202, step S203, or step S205 (step S202: NO, step S203: NO, step S205: NO), the control unit 110 shifts the process to step S206. .

  The control unit 110 sequentially stores the determination results from the first determination to the third determination in the memory (step S206), and until an operation for ending the measurement of the pulse wave is performed via the operation unit 160 (step S207: NO). ), The above-described steps S201 to S206 are repeated. The control unit 110 ends the process when an operation for ending the measurement of the pulse wave is performed via the operation unit 160 (step S207: YES). The operation of the determination process A is as described above. Returning to FIG. 5, the description will be continued.

  The control unit 110 reads out the determination result in step S12 from the memory, and performs a determination process B for the fourth determination (step S13). Hereinafter, the operation of the determination process B will be described. FIG. 7 is an operation flow of the determination process B. The control unit 110 reads out the determination result in step S12 from the memory, and when the determination results from the first determination to the third determination are all positive (step S301: YES), the time measuring unit 130 starts measuring time. (Step S302). Then, the control unit 110 sequentially reads out the determination results from the memory until a predetermined time (for example, 20 seconds) elapses, and checks whether or not all of the read determination results are positive determination results (step S303, Step S304: NO). If any determination result is affirmative until the predetermined time has elapsed, the control unit 110 determines that the measurement site is congested when the predetermined time has elapsed (step S303: YES, step S305). In addition, when none of the determination results from the first determination to the third determination is positive in step S301 or step S303 (step S301: NO or step S303: NO), the control unit 110 determines that the state is a non-congestive state. (Step S306), and the determination process B ends. The operation of the determination process B is as described above. Hereinafter, returning to FIG.

  The control part 110 performs the process which outputs a pulse wave signal based on the determination result of the determination process B of step S13 (step S14). Specifically, if the control unit 110 determines in step S13 that the blood is in a congested state, the control unit 110 calculates the composite acceleration a from each acceleration data (ax, ay, az) for the period in which the blood congested state is determined, A calculation result obtained by convolving the filter coefficient sequence w with the acceleration a is generated as a noise waveform. Then, the control unit 110 uses the result obtained by subtracting the noise waveform signal from the waveform signal of the measurement data output from the first signal processing unit 120a as a pulse wave signal, and the filter coefficient so that the pulse wave signal does not include a noise component. Update column w. If controller 110 determines in step S13 that the patient is in a non-congested state, control unit 110 uses the waveform signal of the measurement data during the period determined to be in the non-congested state as a pulse wave signal. The control unit 110 detects the peak time interval in the waveform of the pulse wave signal identified in step S14 as the pulse interval, detects the frequency of appearance of the peak every predetermined time in the pulse signal waveform as the pulse rate, and detects the detected pulse interval. An image indicating the pulse rate is displayed on the display unit 150 (step S15).

  As described above, in the present embodiment, it is determined whether or not the measurement site is congested based on the output signal from the acceleration sensor 17 and the output signal from the pulse wave sensor 20. As described above, the fact that the blood stasis state can be determined from the acceleration and pulse wave measurement results also appears in the following experimental results of the inventors.

  FIG. 8A and FIG. 9A are diagrams showing the waveforms of the acceleration signal and the measurement signal when the pulse wave is measured using the pulse wave measuring device 1. In this example, the measurement subject wearing the pulse wave measuring device 1 takes a posture of being in a resting state for the first 30 seconds and having the wearing part substantially horizontal (period A), and then facing the wearing part downward for 60 seconds. The fingertips are directed in the direction of gravity to make it easy to stagnate (period B), and then the hand is moved back and forth for 40 seconds with the mounting part facing down (period C), and for the last 20 seconds A series of actions of taking a posture in which the wearing site was substantially horizontal in a resting state (period D) was performed.

  In FIG. 8A, the acceleration “700 to 750” is a value corresponding to the gravitational acceleration, and the vicinity of the acceleration “512” is a value corresponding to the three-axis origin of the acceleration sensor 17. In period A, the acceleration component in the Z-axis direction changes at a value corresponding to the gravitational acceleration, and the X-axis acceleration component changes at a value near the origin. The acceleration component value on the Y axis is slightly below 512, indicating that the elbow is slightly twisted with the measurement device attached. When the period A is shifted to the period B (30 seconds), the acceleration in each axial direction varies greatly, and thereafter, the acceleration in any axial direction hardly varies. In period B, since the fingertip is directed in the direction of gravity with the wearing part facing down, gravitational acceleration is applied to the X axis, and the value changes substantially corresponding to the gravitational acceleration. The fact that the acceleration components of the Y-axis and Z-axis change at a level higher than 512 indicates that the plane formed by the Y-axis and the Z-axis is slightly inclined and not completely horizontal. This state also appears in the waveform of the moving standard deviation calculated for the acceleration of FIG. 8A shown in FIG. That is, in FIG. 8 (b), when the mounting position of the apparatus main body 1 is changed from a horizontal posture to a posture tilted in the direction of gravity, the three-axis acceleration components according to the direction of the force when the hand is tilted. Fluctuates greatly, and the moving standard deviation becomes a large value. Since the hand is not moved after the hand is tilted in the direction of gravity, the acceleration component in any axial direction changes at a low level (0 to 5) with almost no change. When the period B shifts to the period C, the acceleration and the moving standard deviation in each axis direction change in accordance with the magnitude of the hand shaking force while maintaining the magnitude relationship of the three-axis acceleration components in the period B. . When the period C shifts to the period D, the acceleration component in the Z-axis direction changes at a value corresponding to the gravitational acceleration as in the period A.

On the other hand, the waveform of the pulse wave measurement signal shown in FIG. 9A is a waveform corresponding to the acceleration in each period shown in FIG. Specifically, since the periods A and D are in a resting state, the measurement signal in this period has a stable waveform with a constant period, and no blood is congested in these periods. After transition from period A to period B, the amplitude gradually decreases. Period B is a posture and a resting state in which the attachment site is oriented in the direction of gravity as shown in FIG. In this state, since blood circulation becomes dull, an increase in the amount of reduced hemoglobin contained in venous blood increases the amount of absorption of light emitted from the light emitting element, and the amount of reflected light decreases. In addition, since the blood vessel volume and arteriovenous flow are reduced, the expansion and contraction of the blood vessel is weakened. Therefore, the pulse wave amplitude representing the change in the volume of the blood vessel is reduced. 4 or less. This phenomenon also appears in the waveform of the moving standard deviation for the waveform data in FIG. 9A shown in FIG. The moving standard deviation represents the amount of change in the thickness of blood in the subcutaneous blood vessel at the measurement site. In other words, when not congested, arterial blood passes from the upper arm through the measurement site to the fingertip and venous blood flows from the fingertip through the measurement site to the upper arm according to the rhythm of the heartbeat. Then, since the change in the blood volume of the artery and vein becomes small, the amplitude of the moving standard deviation becomes small. Therefore, it can be seen that the blood is congested in period B (30 to 80 seconds).
Next, during period C, since the hand is swung back and forth in a posture that is easily congested, the acceleration greatly fluctuates due to body movement as shown by the waveform in FIG. The waveform is disturbed due to the fluctuation of the amplitude more greatly than in the resting state, but the blood is easily flown by the motion of shaking hands, and the blood is not congested.

  In the embodiment described above, the measurement site is congested based on the acceleration according to the movement and posture of the mounting site on which the apparatus main body 10 is mounted and the amplitude of the measurement signal that changes according to the amount of blood flowing through the measurement site. Whether or not it is in a state can be determined. Further, in the case of a blood congestion state, a pulse wave signal from which a noise component due to the blood congestion state has been removed is output, so that the pulse wave can be measured more accurately.

<Modification>
The present invention is not limited to the above-described embodiment, and may be carried out by being modified as follows. Further, the following modifications may be combined.

(1) In the above-described embodiment, the example in which the threshold value for determining whether or not the patient is in the resting state has been stored in the storage unit 180, but the threshold value corresponding to the living body to be measured is stored. Alternatively, the threshold value in the storage unit 180 may be adjusted by the user via the operation unit 160. Depending on the measurement target, body movements such as tremors may occur even when trying to be in a resting state, so that it is possible to adjust the threshold for each measurement target to determine more accurately whether it is in a resting state Can do.

(2) In the above-described embodiment, the example in which the acceleration sensor 17 is provided on the apparatus main body 10 side has been described. However, for example, even if the acceleration sensor 17 is provided in a housing that houses the pulse wave sensor 20 or the like. Good. In this case, an acceleration signal from the acceleration sensor 17 is acquired via the apparatus main body 10 and the cable 30.

(3) In the above-described embodiment, the light receiving and emitting unit 210 has been described as an example including the light emitting element that emits light of the wavelength of the blue light and the light receiving element that receives the light emitted from the light emitting element. The light emitted by may be green light, infrared light, near infrared light, or the like.

(4) Although the pulse wave sensor 20 in the above-described embodiment has been described as receiving the reflected light of the light irradiated to the measurement site, the pulse wave sensor 20 may be configured to receive the light transmitted through the measurement site. Good.

(5) In the above-described embodiment, the posture detection unit 170 has the triaxial acceleration sensor 17 and the triaxial acceleration sensor 17 detects the physical quantity according to the posture and movement of the wearing part. As a sensor for detecting the physical quantity, a biaxial acceleration sensor or a gyro sensor may be used.

(6) In the above-described embodiment, the pulse wave measuring device 1 is an example in which the device main body 10 and the pulse wave sensor 20 are connected by the cable 30, but the device main body 10, the pulse wave sensor 20, May be configured integrally and attached to the wrist of the measurement subject, for example.

(7) In the above-described embodiment, the example in which the apparatus main body 10 is attached to the wrist like a wristwatch has been described, but the apparatus main body 10 may be an apparatus such as a mobile phone or a portable information terminal. In this case, the apparatus main body 10 and the pulse wave sensor 20 may be configured to be connected by wireless communication.

(8) In the above-described embodiment, the pulse wave measurement device 1 has been described as an example. However, in the blood congestion determination device having the functions of the signal processing unit 120 and the control unit 110 of the device main body 10, a posture detection unit attached to a living body. 170 and the pulse wave sensor 20, the acceleration at the wearing part or the measurement part, the measurement signal at the measurement part are acquired by wireless or wired communication, and the measurement part is congested using the acquired acceleration and the measurement signal. You may make it determine.

(9) In the above-described embodiment, the example of the index finger is described as the measurement site on which the pulse wave sensor 20 is worn, but the back of the hand, the wrist, and the upper arm may be used.

  DESCRIPTION OF SYMBOLS 1 ... Pulse wave measuring device, 10 ... Apparatus main body, 15 ... Display, 16 ... Operation switch, 17 ... Accelerometer, 20 ... Pulse wave sensor, 30 ... Cable, 40 ... Band, 110 ... Control unit, 111 ... Determination unit, 112 ... Pulse wave output unit, 112a ... Adaptive filter processing unit, 112b ... Analysis unit, 120 ... Signal Processing unit, 120a ... first signal processing unit, 120b ... second signal processing unit, 130 ... timing unit, 140 ... clock supply unit, 150 ... display unit, 160 ... operation , 170 ... posture detection unit, 180 ... storage unit, 210 ... light emitting / receiving unit, 220 ... drive unit

Claims (7)

A first acquisition means for acquiring a physical quantity of an attachment part to be attached to a living body or a measurement part for measuring a pulse wave of the living body;
Second acquisition means for acquiring a measurement signal based on the amount of light reflected on the measurement site by the light irradiated on the measurement site;
Said first predetermined condition with respect to tilt with respect to the direction of gravity in the attitude of the installation position in accordance with the prior Symbol physical quantity obtained by the obtaining means, the variation width of the orientation is within a predetermined range, and wherein Determination means for determining that the measurement site is congested when a state satisfying that the fluctuation range of the measurement signal acquired by the second acquisition means is within a predetermined range continues for a certain period of time. And a blood stagnation judging device.   The congestion determination apparatus according to claim 1, wherein the first acquisition unit acquires an acceleration according to a posture and a movement of the wearing part or the measurement part as the physical quantity. A first acquisition means for acquiring an acceleration corresponding to the posture and movement of a wearing part to be worn on a living body or a measurement part for measuring a pulse wave of the living body;
Second acquisition means for acquiring a measurement signal based on the amount of light reflected on the measurement site by the light irradiated on the measurement site;
The posture of the measurement part based on the acceleration acquired by the first acquisition means is a posture inclined in the direction of gravity, the fluctuation range of the acceleration is within a predetermined range, and in a non-congestive state In addition to satisfying each condition that the fluctuation range of the amplitude of the measurement signal with respect to the reference signal indicating the measurement result of the pulse wave is within a predetermined range, the state satisfying each condition continues for a certain period of time. Determination means for determining that the measurement site is congested when the condition of being
A device for determining blood congestion. The congestion determination apparatus according to claim 3 , wherein the predetermined range with respect to the fluctuation range of the acceleration is a range determined according to a pulse wave measurement target. The congestion determination apparatus according to any one of claims 1 to 4,
A light emitting / receiving unit that is attached to a measurement site for measuring a pulse wave, and that outputs a measurement signal based on the amount of light reflected by the measurement site to the blood congestion determination device;
An apparatus for outputting a pulse wave, comprising: an output unit that outputs a pulse wave signal indicating a pulse wave of the living body based on a determination result in the congestion determination apparatus and the measurement signal. First obtaining means obtains the physical quantity of the measurement site for measuring installation position is mounted on the living body, or a pulse wave of a living body,
Second acquisition means, the irradiated light to the measurement site acquires a measurement signal based on the amount of light reflected by the measurement site,
Determination means, is within a range where the first corresponding prior Symbol physical quantity obtained by the obtaining means said predetermined respect inclination with respect to the direction of gravity in the attitude of the mounting site conditions, the variation width of the posture predetermined And when the state satisfying that the fluctuation range of the measurement signal acquired by the second acquisition unit is within a predetermined range continues for a certain period of time, the measurement site is congested you judgment
A method for determining congestion. The first acquisition means acquires the acceleration corresponding to the posture and movement of the mounting part to be mounted on the living body or the measurement part for measuring the pulse wave of the living body,
The second acquisition means acquires a measurement signal based on the amount of light reflected on the measurement site by the light irradiated on the measurement site,
A determination unit is configured such that the posture of the measurement part based on the acceleration acquired by the first acquisition unit is a posture inclined in the direction of gravity, the fluctuation range of the acceleration is within a predetermined range; and While satisfying each condition that the fluctuation range of the amplitude of the measurement signal with respect to the reference signal indicating the measurement result of the pulse wave in the non-congested state is within a predetermined range, the state satisfying each condition is constant. When the condition of continuing for a time is satisfied, the measurement site is determined to be congested
A method for determining congestion.

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