JP2009039264A - Non-invasive biological information measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noninvasive living body information measuring apparatus which can be miniaturized because a measurement abnormality is detected only by an acoustic sensor without newly providing a contact pressure sensor.
A control means for controlling a light source, a light source for irradiating a living body with light of a specific wavelength, a photoacoustic detection means for detecting a photoacoustic wave signal generated in the living body, and a photoacoustic detection. A feature quantity estimating means 50 for estimating the blood sugar level from the output of the means 40 and a feature quantity display means 60 for displaying the estimation result of the blood sugar level are provided. In the feature quantity estimating means 50, light of a specific wavelength is sent to the photoacoustic detection means 40. The measurement state is detected using a change in the photoacoustic wave signal generated by arrival, and if the detection result is an abnormal state, measures such as re-measurement are taken.
[Selection] Figure 2

Description

  The present invention relates to a measuring apparatus, and more particularly to a non-invasive living body information measuring apparatus capable of detecting a measurement error based on a photoacoustic wave signal from a living body and improving measurement accuracy.

  The number of patients with diabetes, a typical lifestyle-related disease, is increasing worldwide. Diabetic patients require routine glycemic control to reduce complications from diabetes and improve the quality of life of patients. Therefore, patients must measure blood glucose regularly every day under the guidance of a doctor. As a typical method for measuring a blood glucose level, there is an invasive blood glucose measuring device that measures blood glucose level by collecting blood by inserting a patient's finger. A noninvasive blood glucose measurement device that does not require blood collection has been proposed because it involves labor and pain when blood is collected by puncturing a finger and there is a risk of infection and the like.

  As a non-invasive blood glucose measurement device, a “biological measurement system” using a photoacoustic effect is described. Light of a wavelength absorbed by glucose is irradiated from a biological measurement system onto a part of a living body such as a fingertip, and the irradiated light is collected at a relatively small focal region in the living body, and is generally light. Is absorbed by glucose and converted to kinetic energy in the tissue in the region adjacent to the focal region. Kinetic energy increases the temperature and pressure of the absorbing tissue region and generates sound waves. This sound wave is hereinafter referred to as “photoacoustic wave signal”. The photoacoustic wave signal is emitted from the absorbing tissue region and detected by an acoustic sensor included in the biological measurement system. The acoustic sensor is mounted in contact with the living body surface. The intensity of the photoacoustic wave signal is a function of glucose in the absorption tissue region, and the intensity measured by the acoustic sensor is used to check the blood glucose level (for example, Patent Document 1).

In such a system, when the contact pressure between the living body surface and the acoustic sensor changes, the photoacoustic wave signal may not be normally transmitted to the acoustic sensor, and as a result, the measurement may become unstable. Therefore, a method for detecting a measurement abnormality by detecting a contact pressure between bioacoustic sensors with a pressure sensor is disclosed (for example, Patent Document 2).
Special table 2001-526557 gazette JP 2003-111750 A

  However, in such a method, in addition to the acoustic sensor, a contact pressure sensor for detecting a measurement abnormality is further required, so that there is a problem that the apparatus becomes complicated and downsizing becomes difficult.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional problems and to provide a noninvasive living body information measuring apparatus that can be downsized because a measurement abnormality is detected only by an acoustic sensor without using a contact pressure sensor. .

  In order to solve the conventional problems, the non-invasive living body information measuring apparatus of the present invention detects a photoacoustic wave signal generated by a specific substance in the living body absorbing light energy by light irradiated on the living body surface on the living body surface. Control means for outputting an irradiation control signal for controlling irradiation of pulsed light that is repeated at least once with respect to one estimation of blood glucose level in a non-invasive living body information measuring device that estimates blood glucose level by And at least one light source that emits the pulsed light toward the surface of the living body according to the irradiation control signal, the pulsed light emitted from the light source or the reflected pulsed light reflected by the living body, and a specific substance in the living body. A photoacoustic detection means for detecting the photoacoustic wave signal detected by a detector having at least one channel and outputting a detection signal sampled at a predetermined frequency; Feature amount estimating means for estimating the blood glucose level using at least one channel averaged detection signal obtained by averaging the detection signal for the number of times of pulsed light irradiation repeated at least once, and displaying the blood glucose level A feature amount display means, wherein the feature amount estimation means uses a change in the detection signal caused by the pulsed light or the reflected pulsed light reaching the photoacoustic detection means to determine whether the measurement state is normal. It is characterized by determining whether or not.

  Furthermore, in the non-invasive living body information measurement apparatus, the feature amount estimation means includes the m detection signals obtained by repeatedly irradiating the pulsed light m times (m is a natural number) in one blood glucose level estimation. Among them, n (n is a natural number equal to or less than m) detection signals are averaged to create a measurement state evaluation signal, and every time a blood glucose level is estimated, the measurement state evaluation signal appears immediately after irradiation with the pulsed light. The amplitude level is extracted from the change, and the amplitude level extracted from the measurement state evaluation signal when the blood glucose level is estimated at the p-th time (p is a natural number up to 2 and the blood sugar level estimation end count), and the blood glucose level before the p-th time An amplitude change amount is calculated from the amplitude level extracted from the measurement state evaluation signal at the time of estimation, and it is determined that the measurement is abnormal when the amplitude change amount is equal to or higher than a measurement state determination level. It is obtained by the features.

  Further, in the non-invasive living body information measuring apparatus, the feature amount estimating means stores the amplitude change amount in a memory provided in the feature amount estimating means every time the blood sugar level is estimated, and the p th (p is 2 or more). When estimating a blood glucose level of (natural number), a plurality of amplitude change amounts that are stored in the memory at least twice and not more than p times are filtered, and the filtered amplitude change amounts are equal to or higher than a measurement state determination level It is characterized by determining that it is a measurement abnormality.

  Further, in the non-invasive living body information measuring apparatus, the feature amount estimation means includes the amplitude level extracted from the measurement state evaluation signal obtained at the time of p-th blood sugar level estimation, and the blood level obtained at the time of p-th previous blood sugar level estimation. The amplitude change amount is calculated using a square error with the amplitude level extracted from the measurement state evaluation signal.

  Further, in the non-invasive living body information measuring apparatus, the feature amount estimating means extracts an amplitude level from each measurement state evaluation signal of at least one channel and uses an average amplitude level obtained by averaging the amplitude level by the number of channels. And calculating the amount of amplitude change.

  Furthermore, in the non-invasive living body information measuring apparatus, the feature amount estimation means includes a measurement abnormal state continuous number counter that counts the number of consecutive measurement states that are not normal, and the count value of the measurement abnormal state continuous number counter is When the abnormal state continuous detection upper limit value is reached, the blood sugar level estimation operation is stopped and the user is notified through the feature amount display means.

  Further, in the noninvasive living body information measuring device, the measurement abnormal state continuous number counter is reset to 0 before the operation of the noninvasive living body information measuring device starts and when the result of determining the measuring state is normal. It is characterized by that.

  Furthermore, in the non-invasive living body information measuring apparatus, the feature amount estimating means is configured to calculate q pieces (q of the number of irradiation times of the pulsed light repeated m times in each estimation of the blood glucose level. Is an arbitrary number of pulsed light irradiations so that the sum of the number of irradiation times of the pulsed light in the measurement state evaluation signal of q or the q measurement state evaluation signals is m times. q measurement state evaluation signals are generated, and the measurement state is determined using any of the measurement state evaluation signals out of q measurement state evaluation signals. It is.

  Further, in the non-invasive living body information measuring apparatus, the feature amount estimating means determines the measurement state from q measurement state evaluation signals in one estimation of blood glucose level, and the measurement state is determined to be normal. If the measured number is larger than the normal state determination constant, it is finally determined that the measurement state is normal, and only the detection signals whose measurement state is determined to be normal among the q detection signals are averaged. The averaged detection signal is created.

  Furthermore, in the non-invasive living body information measurement apparatus, the feature amount estimation means determines the measurement state from q measurement state evaluation signals in one estimation of blood glucose level, and the measurement state is normal. If the determined number is equal to or less than the normal state determination constant, it is finally determined that the measurement state is not normal, the blood glucose level estimation operation is stopped, and the user is notified through the feature amount display means. , Is characterized by that.

  Furthermore, in the non-invasive living body information measurement apparatus, the feature amount estimation means determines the measurement state from q measurement state evaluation signals in one estimation of blood glucose level, and the measurement state is normal. If the determined number is less than or equal to the normal state determination constant, it is determined that the measurement state is not normal, and a series of operations from the irradiation of the pulsed light at least once until the determination of the measurement state is performed again. As a result, when it is determined that the measurement state is not normal, the blood sugar level estimation operation is stopped, and the user is notified through the feature amount display means.

  Furthermore, in the noninvasive living body information measuring apparatus, the feature amount estimating means includes a writable register, and the measurement state determination level can be changed from the outside by the register. It is a feature.

  Furthermore, in the non-invasive living body information measuring apparatus, the feature amount estimation means includes a writable register, and the abnormal state continuous detection upper limit value can be changed from outside by the register. It is characterized by that.

  Further, in the non-invasive living body information measuring apparatus, the feature amount estimating means includes a writable register, and the normal state determination constant can be changed from the outside by the register. It is a feature.

  According to the non-invasive living body information measuring apparatus of the present invention, a measurement abnormality is determined by detecting a measurement abnormality using a change in the detection signal generated when the pulsed light reaches the photoacoustic detection means. However, in the case of a measurement abnormality, it is possible to notify the user to that effect, or to take a remeasurement procedure, so that highly accurate measurement is possible.

  Embodiments of the noninvasive living body information measuring apparatus of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a system configuration according to Embodiment 1 of the present invention. In FIG. 1, 1 is a non-invasive biological information measuring device, 20 is a light source, 201 is pulsed light, 30 is a living body, 31 is a blood vessel, 301 is a photoacoustic wave signal, and 40 is a photoacoustic detection means. Components other than the light source 20 and the photoacoustic detection means 40 constituting the noninvasive living body information measuring apparatus 1 will be described later.

  The noninvasive living body information measuring apparatus 1 is mounted so as to be in contact with the surface of the living body 30 and makes the pulsed light 201 enter. The pulsed light 201 propagates through the living body 30 and is absorbed by glucose in the blood vessel 31 to generate a photoacoustic wave signal 301. The photoacoustic wave signal 301 generated by the glucose in the blood vessel 31 is detected by the photoacoustic detection means 40 in the noninvasive living body information measuring apparatus 1 to estimate the blood sugar level.

  FIG. 2 is a diagram showing a block configuration of the noninvasive living body information measuring apparatus 1 according to Embodiment 1 of the present invention. In FIG. 2, 10 is a control means, 50 is a feature quantity estimation means, and 60 is a feature quantity display means. From the control means 10, the light source 20, the photoacoustic detection means 40, the feature quantity estimation means 50, and the feature quantity display means 60. A non-invasive living body information measuring apparatus 1 is configured. Also, 101 is a measurement period signal, 102 is an irradiation period signal, 103 is an irradiation control signal, 104 is a feature amount display control signal, 401 is a detection signal, 501 is a feature amount estimation signal, 502 is a re-irradiation request signal, and 503 is irradiation. It is a frequency signal.

  The control unit 10 outputs an irradiation control signal 103 for controlling the light irradiation to the light source 20 and the feature amount display unit 60. The light source 20 controlled by the irradiation control signal 103 irradiates the living body 30 with the pulsed light 201. At this time, a part of the pulsed light 201 reaches the photoacoustic detection means 40 directly or reflected by a living body. A photoacoustic wave signal 301 is generated by the pulsed light 201 applied to the living body 30. The photoacoustic detection means 40 detects the photoacoustic wave signal 301, samples it at a predetermined frequency, and converts it into a detection signal 401.

  When the detection signal 401 is input to the feature amount estimation unit 50, the blood sugar level is estimated using the signals (measurement cycle signal 101, irradiation period signal 102, irradiation control signal 103) input from the control unit 10, and the estimation is performed. A feature amount estimation signal 501 that is a blood glucose level is output to the feature amount display means 60, and a re-irradiation request signal 502 and an irradiation number signal 503 that indicate the number of times of irradiation with the pulsed light 201 and the number of times of irradiation are controlled in the case of measurement abnormality. Output to means 10. The measurement period signal 101 indicates a blood sugar level measurement period, and the irradiation period signal 102 indicates a period during which the pulsed light 201 is repeatedly irradiated in the measurement period. The feature quantity display means 60 displays the blood glucose level using the feature quantity estimation signal 501 and also displays the measurement error of the noninvasive living body information measuring apparatus 1 using the feature quantity display control signal 104.

  FIG. 3 is a block diagram showing the configuration of the feature quantity estimation means 50. As shown in FIG. In FIG. 3, 510 is an averaging means, 520 is an estimation means, 530 is a measurement state detection means, 101 is a measurement period signal, 102 is an irradiation period signal, 103 is an irradiation control signal, 401 is a detection signal, and 501 is a feature amount estimation. 503 is an irradiation count signal, 511 is an average detection signal, 512 is an averaging end signal, 513 is a measurement state evaluation signal, 514 is a measurement state evaluation start signal, and 531 is a measurement state detection signal. It is.

  The averaging means 510 averages the detection signal 401 by using the measurement cycle signal 101, the irradiation period signal 102, the irradiation control signal 103, and the detection signal 401, and the averaging detection signal 511 and the average detection signal are sent to the estimation means 520. 511, a measurement state evaluation signal 513 and a measurement state evaluation start signal 514 are output to the measurement state detection means 530.

  The estimation unit 520 estimates a blood glucose level using the averaged detection signal 511 and outputs a feature amount estimation signal 501 as an estimation result to the feature amount display unit 60.

  The measurement state detection unit 530 uses the measurement state evaluation signal 513 and the measurement state evaluation start signal 514 to determine whether the measurement is in a normal state or an abnormal state, and outputs the measurement state detection signal 531 to the averaging unit 510. To do.

  FIG. 4 is a timing chart in which the operation of the noninvasive living body information measuring apparatus 1 according to Embodiment 1 of the present invention is plotted on the time axis. 4, (a) is a measurement period signal 101, (b) is an irradiation period signal 102, (c) is an irradiation control signal 103, (d) is a measurement state evaluation start signal 514, and (e) is a measurement state detection signal. 531 and (f) are the averaging end signals 512, and (g) are the feature quantity estimation signals 501. In the repeated measurement, a series of operations is performed every measurement cycle (5 minutes), with one measurement interval as the measurement unit (0.1 seconds) and the interval until the blood sugar level is estimated as the measurement basic cycle (10 seconds).

  Hereinafter, the operation when the noninvasive living body information measuring apparatus 1 performs continuous blood glucose level measurement will be described with reference to FIGS. 1, 2, 3, and 4. In the first embodiment of the present invention, the measurement is performed at 5-minute intervals.

  First, the noninvasive living body information measuring apparatus 1 is mounted on the surface of a living body 30 such as a patient's arm as shown in FIG. Thereafter, when the patient activates a blood glucose level measurement start switch (not shown) provided in the noninvasive living body information measuring apparatus 1, the control means 10 causes the light source 20, the photoacoustic detection means 40, and the feature quantity estimation means 50 to operate stably. The light source 20 is controlled at the timing of entering, and the blood glucose level is estimated.

  Next, a detailed operation of the feature amount estimation unit 50 according to the passage of time will be described with reference to FIGS. 3 and 4.

  First, before the measurement, the signals (d) and (f) shown in FIG. 4 are initialized to Lo and (e) is initialized to 0, and the first measurement is started. At T4A (time 0 minute), a pulse of the measurement period signal 101 shown in FIG. 4A is generated, and the blood sugar level is estimated. Here, the blood glucose level is estimated once for one pulse of the signal in FIG.

  After the pulse of the measurement cycle signal 101 is generated, the irradiation period signal 102 shown in (b) changes to Hi (T4B), and the repeated irradiation period of the pulsed light 201 starts. While the irradiation period signal 102 shown in (b) is Hi (T4B-T4C), the irradiation control signal 103 shown in (c) repeatedly generates pulses at the intervals of the measurement units, and the pulsed light 201 is irradiated for each pulse. I do.

  In Embodiment 1 of the present invention, 60 pulses of the irradiation control signal 103 are generated while the irradiation period signal 102 is Hi. When the irradiation period signal 102 shown in (b) changes to Lo (T4C), the repetition irradiation period of the pulsed light 201 ends, and the averaging means 510 averages the detection signals 401 for 60 times. The averaged result is stored in a memory provided inside the averaging means 510 and is output to the measurement state detection means 530 as a measurement state evaluation signal 513. At this time, a pulse of the measurement state evaluation start signal 514 shown in (d) is generated (T4D), and the measurement state detection means 530 starts determining whether the measurement state is normal or abnormal.

  The measurement state detection unit 530 performs an operation of only storing the measurement state evaluation signal 513 in the memory provided in the measurement state detection unit 530 during the first measurement, and sets the measurement state detection signal 531 shown in FIG. Is output as (T4E).

  Here, the measurement state detection signal 531 indicates a value from 0 to 3, where 0 is an initial state, 1 is in preparation for determination, 2 is a measurement normal state, and 3 is a measurement abnormal state.

  When the measurement state detection signal 531 shown in (e) is changed to 1, a pulse of the averaging end signal 512 is generated (T4F), and the averaged result of the detection signal 401 stored in the memory inside the averaging means 510 is averaged. The detection signal 511 is sent to the estimation means 520.

  When the blood glucose level is estimated by the estimating means 520, the feature amount estimation signal 501 shown in (g) is updated (T4G).

  When the time reaches 5 minutes, the second measurement is started. At T4H, the pulse of the measurement period signal 101 shown in (a) is generated, and after the generation of the pulse of the measurement period signal 101 as in the first measurement, the irradiation period signal 102 shown in (b) changes to Hi (T4I). ), The repeated irradiation period of the pulsed light 201 starts.

  While the irradiation period signal 102 shown in (b) is Hi (T4I-T4J), the irradiation control signal 103 shown in (c) repeatedly generates pulses at the intervals of the measurement units, and the pulsed light 201 is irradiated for each pulse. I do.

  When the irradiation period signal 102 shown in (b) changes to Lo (T4J), the repeated irradiation period of the pulsed light 201 ends, and the result of averaging the detection signal 401 as in the first measurement is averaged inside the averaging means 510. And is output to the measurement state detection means 530 as a measurement state evaluation signal 513. At this time, a pulse of the measurement state evaluation start signal 514 shown in (d) is generated (T4K), and the measurement state detection means 530 starts determining whether the measurement state is normal or abnormal.

  The measurement state detection means 530 determines the measurement state using the measurement state evaluation signal 513 for the first measurement stored in the memory and the newly input measurement state evaluation signal 513 for the second measurement. A method for determining the measurement state will be described later. Here, a description will be given of a case where it is determined that the second measurement state is normal.

  When the measurement state detection signal 531 shown in (e) is changed to 2, a pulse of the averaging end signal 512 is generated (T4M), and the detection signal 401 at the time of the second measurement stored in the memory inside the averaging means 510 is stored. The averaged result is sent to the estimating means 520 as the averaged detection signal 511.

  When the blood glucose level is estimated by the estimating means 520, the feature amount estimation signal 501 shown in (g) is updated (T4N).

  After time 10 minutes, measurement is performed in the same manner as the second measurement every 5 minutes.

  Although the case where the measurement state is normal has been described so far, the operation when the measurement state becomes an abnormal state will be described next.

  FIG. 5 is a timing chart in which another operation of the non-invasive living body information measuring apparatus 1 is plotted on the time axis. (A) is a measurement cycle signal 101, (b) is an irradiation period signal 102, and (c) is irradiation control. Signals 103 and (d) are a measurement state evaluation start signal 514, (e) is a measurement state detection signal 531, (f) is an averaging end signal 512, and (g) is a feature amount estimation signal 501.

  Compared with the timing chart of FIG. 4, the operations of (d), (e), (f), and (g) are different.

  First, before measurement, signals (d) and (f) shown in FIG. 5 are initialized to Lo and (e) is initialized to 0, and the first measurement is started.

  At T5A (time 0 minute), a pulse of the measurement period signal 101 shown in FIG. 5A is generated, and the blood sugar level is estimated. Here, the blood glucose level is estimated once for one pulse of the signal in FIG.

  After the pulse of the measurement cycle signal 101 is generated, the irradiation period signal 102 shown in (b) changes to Hi (T5B), and the repeated irradiation period of the pulsed light 201 starts.

  While the irradiation period signal 102 shown in (b) is Hi (T5B-T5C), the irradiation control signal 103 shown in (c) repeatedly generates pulses at the intervals of the measurement units, and the pulsed light 201 is irradiated for each pulse. I do.

  When the irradiation period signal 102 shown in (b) changes to Lo (T5C), the repeated irradiation period of the pulsed light 201 ends, and the averaging means 510 averages the detection signals 401 for 60 times. The averaged result is stored in a memory provided inside the averaging means 510 and is output to the measurement state detection means 530 as a measurement state evaluation signal 513. At this time, a pulse of the measurement state evaluation start signal 514 shown in (d) is generated (T5D), and the measurement state detection means 530 starts determining whether the measurement state is normal or abnormal.

  The measurement state detection unit 530 performs an operation of only storing the measurement state evaluation signal 513 in the memory provided in the measurement state detection unit 530 during the first measurement, and sets the measurement state detection signal 531 shown in FIG. Is output as (T5E).

  When the measurement state detection signal 531 shown in (e) changes to 1, a pulse of the averaging end signal 512 is generated (T5F), and the averaging result of the detection signal 401 stored in the memory inside the averaging means 510 is averaged. The detection signal 511 is sent to the estimation means 520.

  When the estimation means 520 estimates the blood glucose level, the feature amount estimation signal 501 shown in (g) is updated (T5G).

  When the time reaches 5 minutes, the second measurement is started. At T5H, the pulse of the measurement period signal 101 shown in (a) is generated, and after the generation of the pulse of the measurement period signal 101 as in the first measurement, the irradiation period signal 102 shown in (b) changes to Hi (T4I). ), The repeated irradiation period of the pulsed light 201 starts.

  While the irradiation period signal 102 shown in (b) is Hi (T5I-T5J), the irradiation control signal 103 shown in (c) repeatedly generates pulses at the intervals of the measurement units, and the pulsed light 201 is irradiated for each pulse. I do.

  When the irradiation period signal 102 shown in (b) changes to Lo (T5J), the repeated irradiation period of the pulsed light 201 ends, and the result of averaging the detection signal 401 in the same way as the first measurement is averaged inside the averaging means 510. And is output to the measurement state detection means 530 as a measurement state evaluation signal 513. At this time, a pulse of the measurement state evaluation start signal 514 shown in (d) is generated (T5K), and the measurement state detection means 530 starts determining whether the measurement state is normal or abnormal.

  Here, when it is determined that the second measurement state is an abnormal state, the measurement state detection signal 531 shown in FIG.

  When the measurement state detection signal 531 changes to 3, the re-irradiation request signal 502 is transmitted to the control means 10, the irradiation period signal 102 shown in (b) changes to Hi again (T5M), and the pulsed light 201 is repeatedly irradiated. The period begins.

  While the irradiation period signal 102 shown in (b) is Hi (T5M-T5N), the irradiation control signal 103 shown in (c) repeatedly generates pulses at the intervals of the measurement units, and the pulsed light 201 is irradiated for each pulse. I do. Here, the number of additional irradiations of the pulsed light 201 is the number of irradiations indicated by the irradiation number signal 503, and in the first embodiment, the number of additional irradiations is 60, which is the same number as in the normal state.

  When the irradiation period signal 102 shown in (b) changes to Lo (T5N), the repeated irradiation period of the pulsed light 201 ends, and the averaging means 510 averages the detection signals 401 for 60 times. The averaged result is stored in a memory provided inside the averaging means 510 and is output to the measurement state detection means 530 as a measurement state evaluation signal 513. At this time, a pulse of the measurement state evaluation start signal 514 shown in (d) is generated (T5O), and the measurement state detection means 530 starts determining whether the measurement state is normal or abnormal.

  If it is determined that the measurement state is normal, the measurement state detection signal 531 shown in (e) changes to 2 (T5P).

  When the measurement state detection signal 531 shown in (e) changes to 2, a pulse of the averaging end signal 512 is generated (T5Q), and the detection signal 401 in the period from T5M to T5N stored in the memory inside the averaging means 510 is detected. The averaged result is sent to the estimating means 520 as the averaged detection signal 511.

  When the blood glucose level is estimated by the estimating means 520, the feature amount estimation signal 501 shown in (g) is updated (T5R).

  After time 10 minutes, measurement is performed in the same manner as the second measurement every 5 minutes.

  Next, a measurement state determination method in the measurement state detection unit 530 will be described in detail with reference to FIGS.

  FIG. 6 is a block diagram showing the configuration of the measurement state detection means 530. In FIG. 6, 513 is a measurement state evaluation signal, 514 is a measurement state evaluation start signal, 531 is a measurement state detection signal, 540 is an amplitude detection means, 550 is a change amount detection means, 560 is a measurement state determination means, 570 is a register, 541 is an amplitude detection signal, 551 is an amplitude change amount, and 571 is a measurement state determination level.

  The amplitude detection unit 540 detects the amplitude of the measurement state evaluation signal 513 using the measurement state evaluation signal 513 and the measurement state evaluation start signal 514, and outputs the amplitude detection signal 541 to the change amount detection unit 550.

  The change amount detection unit 550 detects the change amount from the amplitude detection signal 541 and outputs the amplitude change amount 551 to the measurement state determination unit 560.

  The measurement state determination unit 560 outputs a measurement state detection signal 531 using the amplitude change amount 551 and the measurement state determination level 571 obtained from the register 570.

  FIG. 7 is a timing chart in which the operation of the measurement state detection unit 530 according to Embodiment 1 of the present invention is plotted on the time axis. 7, (a) is a measurement state evaluation start signal 514, (b) is a measurement state evaluation signal 513, (c) is an amplitude change amount 551, and (d) is a measurement state detection signal 531.

  Next, the detailed operation of the measurement state detection unit 530 will be described with reference to FIGS. Here, the operation when the measurement state is determined to be a normal state in the second measurement and an abnormal state in the third measurement will be described.

  First, the signal (c) shown in FIG. 7 is initialized to Lo before measurement, and the value of the measurement state determination level 571 serving as a determination criterion for the measurement state is set in advance in the register 570.

  When the pulse (T7A) of the measurement state evaluation start signal 514 shown in FIG. 7A is generated in the first measurement, the peak level of the measurement state evaluation signal 513 shown in FIG. 7B is detected at the timing of T7B. The peak level detected at this time is L7A.

  The peak detected by the amplitude detection means 540 is generated when a part of the pulse light 201 or the pulse light 201 reflected by the living body 30 reaches the photoacoustic detection means 40 immediately after the irradiation with the pulse light 201.

  The detected peak level is stored in a memory (not shown) provided in the change amount detection means 550. At this time, the amplitude change amount 551 shown in (c) does not change.

  Thereafter, the measurement state detection signal 531 shown in (d) changes to 1 (T7C). When the pulse (T7D) of the measurement state evaluation start signal 514 shown in (a) is generated in the second measurement, the peak level of the measurement state evaluation signal 513 shown in (d) is detected at the timing of T7E. The peak level detected at this time is L7B.

  After detecting the peak level, the change amount detecting means 550 calculates a square error between the peak level L7A stored in the memory at the first measurement and the peak level L7B detected at the second measurement, and is shown in (c). A signal indicating the calculation result L7C (L7B × L7B−L7A × L7A) is generated in the amplitude change amount 551 (T7F).

  When the calculation result is smaller than the measurement state determination level 571 (L7D), the measurement state detection signal 531 is changed to 2 (T7G), and the detected peak level L7B is provided in the memory (see FIG. (Not shown).

  When the pulse (T7H) of the measurement state evaluation start signal 514 shown in (a) is generated in the third measurement, the peak level of the measurement state evaluation signal 513 shown in (d) is detected at the timing of T7I. The peak level detected at this time is L7E.

  After detecting the peak level, the change amount detecting means 550 calculates a square error between the peak level L7B stored in the memory at the second measurement and the peak level L7E detected at the third measurement, and is shown in (c). A signal indicating the calculation result L7F = (L7E × L7E−L7B × L7B) is generated in the amplitude change amount 551 (T7J).

  When the calculation result is equal to or higher than the measurement state determination level 571 (L7D), the measurement state detection signal 531 is changed to 3 (T7G). At this time, the contents of the memory provided in the change amount detection means 550 are not updated. The measurement state is determined by the above operation.

  In the first embodiment, the case where the detection signal 401 is 1 ch has been described. However, the present invention can also be applied to, for example, a non-invasive living body information measuring apparatus including a plurality of ch detection signals 401. In that case, the amplitude detection means 540 may detect the peak levels of a plurality of channels, square the peak levels, and then average the number of channels as the amplitude detection signal 541.

  The measurement state determination level 571 that is a determination criterion for the measurement state is obtained, for example, by performing an environmental load test so that the magnitude of the amplitude change amount 551 changes in the adjustment process before factory shipment. The measurement state determination level 571 that satisfies the required blood glucose level estimation accuracy may be determined while monitoring the accuracy of the estimated blood glucose level.

  Further, the measurement state determination level 571 can be set to an arbitrary value from the outside after shipment from the factory by the register 570.

  For this purpose, the determination criterion of the measurement state may be adaptively changed according to the use environment of the noninvasive living body information measuring apparatus 1 in the first embodiment. For example, if it is a noninvasive biological information measuring device that regularly measures blood sugar levels with an invasive blood sugar measuring device and maintains the blood sugar level estimation accuracy using the results, it is measured when determining the noninvasive blood glucose level. A plurality of estimated blood glucose levels may be obtained using the state determination level 571 as a parameter, and the value of the register 570 may be updated with the measurement state determination level at which the most accurate result is obtained.

  In the first embodiment, the case is described in which the abnormal state is resolved and returned to the normal state in the next measurement that is determined to be the abnormal state, but the abnormal state is continuously detected. If the re-irradiation of the pulsed light 201 is repeated, the measurement cycle ends, and as a result, the blood sugar level estimation result may not be obtained.

  Therefore, if an abnormal state continuous detection counter (not shown) is provided inside the measurement state detection means 530, it is possible to cope with a case where abnormal states continue.

  The operation when the abnormal state continuous detection counter is provided inside the measurement state detection means 530 will be described below.

  First, the initial value of the abnormal condition continuous detection counter is set to the abnormal condition continuous detection upper limit before measurement. In the first embodiment, the upper limit value of abnormal state continuous detection is set to 3.

  Similar to the first embodiment described above, the measurement state detection signal 531 shown in FIG.

  If it is determined that the state is abnormal in the second measurement, the measurement state detection signal 531 changes to 3.

  At this time, the abnormal state continuous detection counter counts down and the count value becomes 2.

  If it is determined that an abnormal state is detected even in the third measurement, the measurement state detection signal 531 remains 3 while the count value indicated by the abnormal state continuous detection counter is 1.

  Further, if it is determined that the measurement state is abnormal even in the fourth measurement, the measurement state detection signal 531 remains 3 while the count value indicated by the abnormal state continuous detection counter is zero.

  When the count value indicated by the abnormal state continuous detection counter becomes 0, the operation of the noninvasive living body information measuring apparatus is stopped, and an error is notified to the user.

  In the third or fourth measurement, if it is determined that the state is normal, the count value indicated by the abnormal state continuous detection counter is set to 3, which is the abnormal state continuous detection upper limit value.

  With the above operation, the user can know that the abnormal measurement state is present at an early stage when the abnormal state continues, and can take measures such as reattaching the non-invasive biological information measuring device to the living body 30. It becomes.

  In the noninvasive living body information measuring apparatus 1 in the first embodiment, the pulsed light 201 is irradiated a plurality of times while the irradiation period signal 102 is Hi, and the plurality of detection signals 401 obtained as a result are averaged, and then the blood glucose level is calculated. As estimated, multiple irradiations are not necessarily required. Although it is possible to improve the SNR of the detection signal 401 by irradiating a plurality of times, the SNR of the detection signal 401 is minimum to estimate the blood glucose level by increasing the power of the pulsed light 201 emitted from the light source 20. When the necessary SNR is achieved, the blood sugar level may be estimated for each irradiation of the pulsed light 201 without averaging. At this time, the measurement state detection unit 530 also operates every time the pulsed light 201 is irradiated.

  In the noninvasive living body information measuring apparatus 1 according to the first embodiment, a detection signal obtained by averaging the number of times (60 times) necessary for estimating the blood glucose level in order to determine the measurement state in the measurement state detection unit 530 401 is used, but the number of times of averaging of the detection signal 401 for determining the measurement state can be arbitrarily set.

  For example, the first measurement state determination number may be set to 30 in advance by a register (not shown), and the measurement state may be determined by the following method.

  First, when the number of times of irradiation of the pulsed light 201 performed 60 times in the first measurement reaches 30 times, the detection signal 401 for 30 times is averaged, and the result is used to change the amount of the detection signal 401 inside. The amplitude detection signal 541 is stored in the memory.

  Subsequently, the detection signal 401 with respect to the 31st to 60th pulse light 201 is averaged, and measurement is performed using the amplitude detection signal 541 obtained from the result and the signal stored in the memory inside the variation detection means 550. Judge the state.

  When it is determined that the measurement state is a normal state, the memory inside the variation detection means 550 is updated with the amplitude detection signal 541 obtained from the averaged result of the detection signal 401 for the 31st to 60th pulsed light 201. In addition, in the second measurement, the measurement state of the detection signal 401 in the first to 30th pulsed light 201 is determined.

  Further, in the first measurement, when it is determined that the measurement state is an abnormal state from the averaged result of the detection signals 401 for the 31st to 60th pulse lights 201, the 61st to 90th pulse lights 201 Perform additional irradiation and determine the measurement state again.

  As a result, when it is determined that the state is normal, the averaging means 510 averages the detection signal 401 for the first to 30th and 61st to 90th pulse light 201 irradiations, and the result is output. The blood sugar level is estimated using the averaged detection signal 511. Thereafter, the measurement state is determined every time the pulsed light 201 is irradiated 30 times.

  When the above method is used, the measurement state can be determined from the first measurement without waiting for the second measurement. Alternatively, the following method may be used by setting the second measurement state determination number of times and the normal state determination constant number of 8 times by a register (not shown).

  First, when the number of times of irradiation of the pulsed light 201 performed 60 times in the first measurement reaches the second measurement state determination number (5 times), the detection signals 401 for five times are averaged, and the result is obtained. By using this, the amplitude detection signal 541 is stored in the memory inside the change amount detection means 550.

  Subsequently, the detection signal 401 is averaged every fifth time from the sixth time to the 60th time, and the measurement state is judged.

  When the measurement normal state is 9 times out of the measurement states obtained 11 times in total, it is larger than the normal state judgment constant (8 times), and thus the measurement abnormal state 2 × 5 times = 10 detection signals 401 The blood glucose level is estimated using the detection signal 401 in the remaining number of times of irradiation of the pulsed light 201 excluding the above. At this time, the memory in the change amount detection unit 550 is updated using the averaged result obtained from the detection signal 401 in the latest measurement normal state.

  If the measurement normal state is equal to or less than the normal state determination constant (8 times) among the measurement states obtained a total of 11 times, the pulse light 201 is irradiated again for the second measurement state determination number (5 times), and the measurement is performed. Determine the state. By the above method, the re-irradiation period of the pulsed light 201 for determining the measurement state can be shortened.

  In the noninvasive living body information measuring apparatus 1 according to the first embodiment, when calculating the amount of change in the amplitude detection signal 541 newly obtained in the determination of the measurement state, the amplitude obtained as the comparison target one time before is calculated. Although the detection signal 541 is used, the amplitude detection signal 541 to be compared here can be set at an arbitrary timing in the past.

  This method can be realized by setting the memory provided in the variation detection means 550 for storing the amplitude detection signal 541 to an arbitrary capacity.

  For example, the reference signal storage constant is set to 2 in advance by a register (not shown), and the amplitude detection signal 541 obtained twice before the change amount comparison is used in the change amount detection means 550.

  That is, if the amplitude detection signal 541 input to the change amount detection unit 550 at the kth time is In (k) and the amplitude change amount 551 output from the change amount detection unit 550 at the kth time is Out (k), Out (k) ) = In (k) × In (k) −In (k−2) × In (k−2).

  In the calculation of Out (k) = In (k) × In (k) −In (k−1) × In (k−1) in the variation detection unit 550 already described above, the characteristic of the variation detection unit 550 is HPF. On the other hand, the characteristic of the variation detection means 550 when the reference signal storage constant is 2 has the characteristic of BPF.

  Therefore, by changing the reference signal storage constant, it is possible to realize the change amount detecting means 550 corresponding to the change in frequency appearing in the change amount of the amplitude detection signal 541 when an abnormal state to be detected occurs. .

  Further, the calculation in the change amount detection means 550 may be configured by using not only the amplitude detection signal 541 at two timings (kth and k + 2th input signals) but also three or more timings. In this case, it is possible to realize a filter having a desired frequency characteristic by using a known FIR filter or the like in which the tap coefficient can be arbitrarily set, and it is possible to efficiently detect a measurement abnormal state. .

  As described above, in the noninvasive living body information measuring apparatus 1 described in the first embodiment of the present invention, it is possible to detect a change in the measurement environment of the blood sugar level. It is possible to prevent accidents such as the patient overdosing insulin with respect to the value.

  Note that the target to be measured by the noninvasive living body information measuring apparatus 1 in Embodiment 1 of the present invention is not limited to the amount of glucose in the blood vessel 31. That is, any substance that absorbs energy in the wavelength region of the irradiated pulsed light 201 and generates a photoacoustic wave may be used. For example, glucose contained in tissue fluid between the surface of the living body 30 and the blood vessel 31, The present invention can also be applied to the amount of hemoglobin.

  The non-invasive living body information measuring apparatus according to the present invention can detect a measurement abnormality only with an acoustic sensor without using a contact pressure sensor, thereby eliminating the complexity of the apparatus and reducing the size.

The figure which shows the usage example of the noninvasive biological information measuring device 1 in Embodiment 1 of this invention. The block diagram which shows the structure of the noninvasive biological information measuring device 1 in Embodiment 1 of this invention. The block diagram which shows the structure of the feature-value estimation means 50 in Embodiment 1 of this invention. Timing chart showing operation of noninvasive living body information measuring device 1 in Embodiment 1 of the present invention Timing chart showing another operation of noninvasive living body information measuring device 1 in Embodiment 1 of the present invention. The block diagram which shows the structure of the measurement state detection means 530 in Embodiment 1 of this invention. Timing chart showing operation of measurement state detection means 530 in Embodiment 1 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Noninvasive biological information measuring device 10 Control means 20 Light source 30 Living body 31 Blood vessel 40 Photoacoustic detection means 50 Feature quantity estimation means 60 Feature quantity display means 101 Measurement period signal 102 Irradiation period signal 103 Irradiation control signal 104 Feature quantity display control signal 201 Pulse light 301 Photoacoustic wave signal 401 Detection signal 501 Feature quantity estimation signal 502 Re-irradiation request signal 503 Irradiation frequency signal 510 Averaging means 511 Averaging detection signal 512 Detection signal averaging end pulse 513 Measurement state evaluation signal 514 Measurement state evaluation start Signal 520 Estimation means 530 Measurement state detection means 531 Measurement state detection signal 540 Amplitude detection means 541 Amplitude detection signal 550 Change amount detection means 551 Amplitude change amount 560 Measurement state determination means 570 Register 571 Measurement state determination level

Claims (14)

In a non-invasive living body information measuring apparatus for estimating a blood glucose level by detecting a photoacoustic wave signal emitted from a specific substance in a living body by absorbing light energy by light irradiated on the living body surface,
Control means for outputting an irradiation control signal for controlling irradiation of the pulsed light that is repeated at least once for one estimation of blood glucose level;
At least one light source that irradiates the surface of the living body with the pulsed light according to the irradiation control signal;
The pulsed light emitted from the light source or the reflected pulsed light reflected by the living body and the photoacoustic wave signal generated by the specific substance in the living body are detected by at least one channel detector and sampled at a predetermined frequency. Photoacoustic detection means for outputting a detection signal;
A feature amount estimating means for estimating the blood glucose level using an averaged detection signal of at least one channel obtained by averaging the detection signal for the number of times of irradiation of the pulsed light repeated at least once.
Feature amount display means for displaying the blood glucose level,
The feature amount estimation means determines whether or not the measurement state is normal using a change in the detection signal caused by the pulsed light or the reflected pulsed light reaching the photoacoustic detection means. Non-invasive biological information measuring device. The feature amount estimation means is configured to perform n (n is less than or equal to m) out of m detection signals obtained by repeatedly irradiating the pulsed light m times (m is a natural number) in one blood glucose level estimation. A natural number) detection signal is averaged to create a measurement state evaluation signal,
Extracting the amplitude level from the change that appears immediately after irradiation of the pulsed light in the measurement state evaluation signal every time the blood glucose level is estimated,
The amplitude level extracted from the measurement state evaluation signal at the time of estimating the blood glucose level at the p-th time (p is a natural number equal to or greater than 2 and the number of times the blood sugar level estimation is completed), and the measurement state evaluation signal at the time of blood glucose level estimation before the p-th time An amplitude change amount is calculated from the extracted amplitude level,
The noninvasive living body information measuring apparatus according to claim 1, wherein when the amplitude change amount is equal to or higher than a measurement state determination level, it is determined that the measurement is abnormal. The feature amount estimating means stores the amplitude change amount in a memory provided in the feature amount estimating means every time the blood sugar level is estimated, and the memory is estimated at the p-th time (p is a natural number of 2 or more). And filtering a plurality of amplitude change amounts not less than twice and not more than p times, and when the filtered amplitude change amount is equal to or higher than a measurement state determination level, it is determined that the measurement is abnormal. The noninvasive living body information measuring device according to claim 2. The feature quantity estimating means extracts the amplitude level extracted from the measurement state evaluation signal obtained at the time of p-th blood sugar level estimation and the amplitude level extracted from the measurement state evaluation signal obtained at the time of blood glucose level estimation before the p-th time. The non-invasive biological information measuring apparatus according to claim 2, wherein the amplitude change amount is calculated using a square error with respect to. The feature amount estimating means extracts amplitude levels from the measurement state evaluation signals of at least one channel and calculates the amplitude change amount using an average amplitude level obtained by averaging the amplitude levels by the number of channels. The noninvasive living body information measuring device according to claim 1 characterized by things. The feature amount estimation means includes a measurement abnormal state continuous number counter that counts the number of consecutive measurement states that are not normal, and the count value of the measurement abnormal state continuous number counter reaches an abnormal state continuous detection upper limit value. The non-invasive biological information measuring apparatus according to claim 1, wherein the blood glucose level estimation operation is stopped and the user is notified through the feature amount display means. The said measurement abnormal state continuous number counter is reset to 0 before the operation | movement start of the said noninvasive biological information measuring device and when the result of having determined the said measurement state is normal. Non-invasive living body information measuring device. In the estimation of blood glucose level in one time, the feature amount estimation means is q (q is a natural number of 2 or more) of the measurement states in which the number of times of irradiation is uniform among the number of times of irradiation of the pulsed light. Create q measurement state evaluation signals each having an arbitrary number of pulsed light irradiations so that the sum of the number of pulsed light irradiations in the evaluation signal or q measurement state evaluation signals is m. The non-invasive living body information measuring apparatus according to claim 1, wherein the measurement state is determined by using any of the measurement state evaluation signals among q measurement state evaluation signals. The feature amount estimation means determines the measurement state from q measurement state evaluation signals in one estimation of blood glucose level, and the number of times that the measurement state is determined to be normal is greater than a normal state determination constant. In some cases, it is finally determined that the measurement state is normal, and the averaged detection signal is created by averaging only the detection signals whose measurement state is determined to be normal among the q detection signals. The noninvasive living body information measuring device according to claim 8 characterized by things. The feature amount estimation means determines the measurement state from q measurement state evaluation signals in one estimation of blood glucose level, and the number of times that the measurement state is determined to be normal is equal to or less than a normal state determination constant 9. The non-invasive biological information according to claim 8, wherein the non-invasive living body information according to claim 8, wherein it is finally determined that the measurement state is not normal, the blood glucose level estimation operation is stopped, and the user is notified through the feature amount display means. measuring device. The feature amount estimation means determines the measurement state from q measurement state evaluation signals in one estimation of blood glucose level, and the number of times that the measurement state is determined to be normal is equal to or less than a normal state determination constant If it is, it is determined that the measurement state is not normal, and a series of operations from the irradiation of the pulsed light at least once until the determination of the measurement state is performed again. As a result, the measurement state is not normal. 9. The noninvasive living body information measuring apparatus according to claim 8, wherein when judged, the blood glucose level estimating operation is stopped and the user is notified through the feature amount display means. The non-invasive living body according to claim 2, wherein the feature amount estimation unit includes a writable register, and the measurement state determination level can be changed from the outside by the register. Information measuring device. The non-invasive biological information measurement according to claim 6, wherein the feature amount estimation unit includes a writable register, and the upper limit value of the abnormal state continuous detection can be changed from outside by the register. apparatus. The non-invasive living body according to claim 9, wherein the feature amount estimation unit includes a writable register, and the normal state determination constant can be changed from the outside by the register. Information measuring device.

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