Biological information processing system, processing device, and computer program

Abstract

To provide an improved index related to oxygen saturation of blood contained in a biological tissue and a tissue blood amount by a simple method.SOLUTION: The light emitting device 11 emits first light including a first wavelength λ 1 at which the light absorption coefficient of oxygenated hemoglobin is larger than the light absorption coefficient of deoxygenated hemoglobin, and second light including a second wavelength λ 2 at which the light absorption coefficient of deoxygenated hemoglobin is larger than the light absorption coefficient of oxygenated hemoglobin. The light-receiving device 12 outputs a first signal I1 and a second signal I2 corresponding to the intensity of the first light beam and the intensity of the second light beam transmitted through the biological tissue T. The processing device 13 acquires a first differential value between the light attenuation of the first light beam and the light attenuation of the second light beam based on the first signal I1 and the second signal I2 during the compression of the biological tissue T, acquires a second differential value between the light attenuation of the first light beam and the light attenuation of the second light beam based on the first signal I1 and the second signal I2 after the compression is released, and acquires an indicator corresponding to a blood-oxygen saturation level included in the biological tissue T from a differential between the first differential value and the second differential value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a system for processing biometric information of a subject, a processing device included in the system, and a computer program executable by a processor installed in the processing device. [Background technology]

[0002] Patent Document 1 discloses a device for estimating capillary refill time (CRT). Specifically, light with a wavelength absorbed by blood is irradiated onto biological tissue, such as a fingertip, and the intensity of the light transmitted through the biological tissue is measured. When the biological tissue is compressed, blood is expelled from the biological tissue, increasing the intensity of the transmitted light. When the compression is released, blood refills the biological tissue, decreasing the intensity of the transmitted light. CRT is estimated based on the time it takes for the transmitted light intensity to return to its original level after the compression is released. CRT is also used as an index reflecting the tissue blood volume of a subject. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-115640 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need to provide improved indicators of blood oxygen saturation and tissue blood volume in a simple manner. [Means for solving the problem]

[0005] A first example of an aspect to achieve the above object is a biometric information processing system, a light emitting device that emits first light having a first wavelength at which the absorption coefficient of oxygenated hemoglobin is greater than that of deoxygenated hemoglobin, and second light having a second wavelength at which the absorption coefficient of deoxygenated hemoglobin is greater than that of oxygenated hemoglobin; a light receiving device that outputs a first signal and a second signal corresponding to the intensity of the first light and the intensity of the second light, respectively, that have passed through a biological tissue of a subject; a processing device that receives the first signal and the second signal; It is equipped with The processing device includes: obtaining a first difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal during compression of the biological tissue; acquiring a second difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal after the compression of the biological tissue is released; An index corresponding to the oxygen saturation level of the blood contained in the biological tissue is obtained based on the difference between the first difference value and the second difference value.

[0006] A second embodiment of the present invention is a processing device for achieving the above object, comprising: an interface that receives a first signal corresponding to the intensity of first light having a first wavelength at which the absorption coefficient of oxygenated hemoglobin passing through biological tissue of the subject is greater than the absorption coefficient of deoxygenated hemoglobin, and a second signal corresponding to the intensity of second light having a second wavelength at which the absorption coefficient of deoxygenated hemoglobin passing through the biological tissue is greater than the absorption coefficient of oxygenated hemoglobin; a processor; It is equipped with The processor: obtaining a first difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal during compression of the biological tissue; acquiring a second difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal after the compression of the biological tissue is released; An index corresponding to the oxygen saturation level of the blood contained in the biological tissue is obtained based on the difference between the first difference value and the second difference value.

[0007] A third example of the present invention for achieving the above object is a computer program executable by a processor installed in a processing device, When executed, the processing device: receiving a first signal corresponding to the intensity of first light having a first wavelength at which the absorption coefficient of oxygenated hemoglobin passing through the biological tissue of the subject is greater than the absorption coefficient of deoxygenated hemoglobin, and a second signal corresponding to the intensity of second light having a second wavelength at which the absorption coefficient of deoxygenated hemoglobin passing through the biological tissue is greater than the absorption coefficient of oxygenated hemoglobin; obtaining a first difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal during compression of the biological tissue; acquiring a second difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal after the compression of the biological tissue is released; An index corresponding to the oxygen saturation level of the blood contained in the biological tissue is obtained based on the difference between the first difference value and the second difference value.

[0008] The biological tissue includes blood and non-blood tissue. When blood is removed by compression, the first difference value reflects the attenuation of the non-blood tissue. On the other hand, when blood returns by releasing compression, the second difference value reflects both the attenuation of the blood and the attenuation of the non-blood tissue.

[0009] Since the oxygen saturation of blood changes from moment to moment, the attenuation also changes. However, the first difference value does not fluctuate because it excludes the influence of blood. On the other hand, the second difference value fluctuates according to changes in the oxygen saturation of blood. Therefore, the difference between the first difference value and the second difference value can be an index that more accurately reflects changes in the oxygen saturation of blood.

[0010] In addition, since the unchanging first difference value can be treated as a reference value, once compression of the biological tissue is performed, the indicator can be continuously monitored by subsequently obtaining the second difference value intermittently or continuously.

[0011] The above-described effects can be achieved without adding any special devices or mechanisms to the bioinformation system, and therefore an improved indicator of blood oxygen saturation in biological tissue can be provided in a simple manner.

[0012] A fourth example aspect for achieving the above object is a biometric information processing system, comprising: a light emitting device that emits light having a wavelength in the range of 800 nm to 950 nm; a light receiving device that outputs a signal corresponding to the intensity of the light transmitted through the biological tissue of the subject; a processor that receives the signal; It is equipped with The processing device includes: obtaining a first attenuation of the light based on the signal during compression of the biological tissue; obtaining a second attenuation of the light based on the signal before compression of the biological tissue or after compression of the biological tissue is released; obtaining an index corresponding to the amount of blood contained in the biological tissue based on a difference between the first attenuation and the second attenuation; Biometric information processing system.

[0013] A fifth example aspect of the present invention is a processing device that includes: an interface that receives a signal corresponding to the intensity of light having a wavelength in the range of 800 nm to 950 nm that has passed through the biological tissue of the subject; a processor; It is equipped with The processor: obtaining a first attenuation of the light based on the signal during compression of the biological tissue; obtaining a second attenuation of the light based on the signal before compression of the biological tissue or after compression of the biological tissue is released; obtaining an index corresponding to the amount of blood contained in the biological tissue based on a difference between the first attenuation and the second attenuation; Processing equipment.

[0014] A sixth aspect of the present invention is a computer program executable by a processor installed in a processing device, the computer program comprising: When executed, the processing device: receiving a signal corresponding to the intensity of light having a wavelength in the range of 800 nm to 950 nm that has passed through the subject's biological tissue; obtaining a first attenuation of the light based on the signal during compression of the biological tissue; obtaining a second attenuation of the light based on the signal before compression of the biological tissue or after compression of the biological tissue is released; obtaining an index corresponding to the amount of blood contained in the biological tissue based on a difference between the first attenuation and the second attenuation; Computer program.

[0015] The biological tissue includes blood and non-blood tissue. When blood is removed by compression, the first attenuation reflects the attenuation of the non-blood tissue. On the other hand, when blood returns by releasing compression, the second attenuation reflects both the attenuation of the blood and the attenuation of the non-blood tissue.

[0016] As the amount of blood changes from moment to moment, the attenuation also changes. However, since the first attenuation excludes the influence of blood, its value does not fluctuate. On the other hand, the second attenuation fluctuates according to changes in the amount of blood. Therefore, the difference between the first attenuation and the second attenuation can be an index that more accurately reflects changes in the amount of blood.

[0017] In addition, since the unchanging first attenuation can be treated as a reference value, once compression of the biological tissue is performed, the index can be continuously monitored by subsequently acquiring the second attenuation intermittently or continuously.

[0018] The above-described effects can be achieved without adding any special devices or mechanisms to the bioinformation system, and thus an improved indicator of the amount of blood contained in biological tissue can be provided in a simple manner. [Brief explanation of the drawings]

[0019] [Figure 1] 1 illustrates a functional configuration of a pulse oximeter according to an embodiment. [Figure 2] FIG. 2 is a diagram for explaining a process executed by the processing device of FIG. [Figure 3] FIG. 2 is a diagram for explaining a process executed by the processing device of FIG. [Figure 4] FIG. 2 is a diagram for explaining a process executed by the processing device of FIG. [Figure 5] 10 illustrates a functional configuration of a photometry system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The following detailed description of exemplary embodiments will be given with reference to the accompanying drawings, in which the scale of each illustrated element is appropriately changed so as to make it recognizable.

[0021] 1 illustrates the functional configuration of a pulse oximeter 10 according to an embodiment. The pulse oximeter 10 is a device that calculates the transcutaneous arterial oxygen saturation (SpO2) of a subject based on the concentration of a light-absorbing substance contained in the subject's arterial blood. The pulse oximeter 10 is an example of a bioinformation processing system.

[0022] The pulse oximeter 10 includes a light-emitting device 11. The light-emitting device 11 includes a first light-emitting element 111 and a second light-emitting element 112. The first light-emitting element 111 is configured to emit a first light having a first wavelength λ1. The second light-emitting element 112 is configured to emit a second light having a second wavelength λ2.

[0023] The first wavelength λ1 is selected as a wavelength at which the absorption coefficient of oxygenated hemoglobin is greater than that of deoxygenated hemoglobin, and an example of the first wavelength λ1 is 940 nm.

[0024] The second wavelength λ2 is selected as a wavelength at which the absorption coefficient of deoxygenated hemoglobin is greater than that of oxygenated hemoglobin. An example of the second wavelength λ2 is 660 nm.

[0025] Each of the first light emitting element 111 and the second light emitting element 112 can be a semiconductor light emitting element. Examples of the semiconductor light emitting element include a light emitting diode, a laser diode, and an EL element.

[0026] The pulse oximeter 10 includes a light-receiving device 12. The light-receiving device 12 includes a light-receiving element. The light-receiving element is configured to output a first signal I1 and a second signal I2 corresponding to the intensity of a first light and the intensity of a second light, respectively, at a light-receiving surface. Each of the first signal I1 and the second signal I2 may be an analog signal or a digital signal. Examples of the light-receiving element include a photodiode, a phototransistor, and a photoresistor.

[0027] The pulse oximeter 10 includes a processing device 13. The processing device 13 includes an input interface 131. The input interface 131 is configured to receive a first signal I1 and a second signal I2 output from the light receiving device 12. When the first signal I1 and the second signal I2 are each analog signals, the input interface 131 includes an appropriate conversion circuit including an A / D converter. This description similarly applies to other signals that can be received by the input interface 131, which will be described later.

[0028] The processing device 13 includes a processor 132. The processor 132 is configured to execute processes for realizing various functions described below.

[0029] The processing device 13 includes an output interface 133. The output interface 133 is configured to output a light-emitting control signal EC for causing the light-emitting device 11 to perform a predetermined light-emitting operation. The light-emitting control signal EC may be an analog signal or a digital signal depending on the specifications of the light-emitting device 11. When the control signal is an analog signal, the output interface 133 includes an appropriate conversion circuit including a D / A converter. This description similarly applies to other signals that can be output by the output interface 133, which will be described later.

[0030] Specifically, the processor 132 outputs a light emission control signal EC that causes the light emitting device 11 to alternately emit the first light and the second light from the output interface 133. The first light emitting element 111 and the second light emitting element 112 alternately emit the first light and the second light at the timing specified by the light emission control signal EC.

[0031] The first light and the second light are alternately incident on the subject's biological tissue T. The first light and the second light that have passed through the biological tissue T are alternately incident on the light receiving surface of the light receiving device 12.

[0032] Therefore, the light receiving device 12 alternately outputs the first signal I1 and the second signal I2. The processor 132 of the processing device 13 identifies which signal has been received by the input interface 131 based on the timing at which the light emission control of the first light emitting element 111 and the second light emitting element 112 is performed.

[0033] The processor 132 is configured to calculate the subject's SpO2 based on the intensity of the first signal I1 and the intensity of the second signal I2.

[0034] Specifically, since the intensity of the first light emitted from the first light-emitting element 111 and the intensity of the second light emitted from the second light-emitting element 112 are known, the attenuation A1 of the first light and the attenuation A2 of the second light accompanying passage through biological tissue T can be calculated from the received intensities of the first light and the second light at the light-receiving device 12 corresponding to the first signal I1 and the second signal I2. SpO2 is correlated with the ratio between the attenuation A1 of the first light and the attenuation A2 of the second light. Therefore, the value of SpO2 can be calculated by inputting this ratio into a function corresponding to this correlation.

[0035] The attenuation A1 of the first light is expressed by the following formula. A1=Ab1+At1=Eb1·Hb·Db+Zt1·Dt (1) Ab1: Primary light attenuation from blood At1: Primary light attenuation from tissues other than blood Eb1: Absorption coefficient of blood for the first light (dL g -1 ·cm -1 ) Hb: Hemoglobin concentration in blood (g dL -1 ) Db: Blood thickness (cm) Zt1: The attenuation rate of the first light in tissues other than blood (cm -1 ) Dt: thickness of tissue other than blood (cm)

[0036] Similarly, the attenuation A2 of the second light is expressed by the following equation. A2=Ab2+At2=Eb2·Hb·Db+Zt2·Dt (2) Ab2: Secondary light attenuation from blood At2: Secondary light attenuation from tissues other than blood Eb2: absorption coefficient of blood for the second light (dL g -1 ·cm -1 ) Zt2: Extinction rate of the second light in tissues other than blood (cm -1 )

[0037] Because the wavelength dependency of the attenuation rate of tissues other than blood is considered to be low, Zt1 can be considered to be equal to Zt2. Therefore, by obtaining the difference ΔA between the attenuation rate A1 of the first light and the attenuation rate A2 of the second light, the influence of tissues other than blood on the attenuation rate can be eliminated. ΔA=A1-A2=Ab1-Ab2=(Eb1-Eb2)·Hb·Db (3)

[0038] When the biological tissue T is compressed, a change occurs in the attenuation A1 of the first light and the attenuation A2 of the second light. The compression may be performed manually by the user or mechanically by an actuator or the like.

[0039] FIG. 2 illustrates the change over time of the difference value ΔA calculated as described above. When compression begins at time t1, blood is expelled from the biological tissue T, and the received light intensities of both the first light and the second light increase. Accordingly, the difference value ΔA also increases. When compression is released at time t2, blood returns to the biological tissue T, and the received light intensities of both the first light and the second light decrease. Accordingly, the difference value ΔA also decreases.

[0040] The processor 132 is configured to acquire, based on the first signal I1 and the second signal I2 received by the input interface 131 during compression of the biological tissue T, a difference value between the attenuation A1 of the first light and the attenuation A2 of the second light during that period as a first difference value ΔAp1. The first difference value ΔAp1 may be acquired as a difference value at any time point during the period from time t1 to time t2 in FIG. 2, or may be acquired as a statistical value of difference values ​​during any interval during that period. Examples of statistical values ​​include an average value, a median value, and a mode value.

[0041] Additionally, the processor 132 is configured to acquire, as a second difference value ΔAp2, a difference value between the attenuation A1 of the first light and the attenuation A2 of the second light during the period based on the first signal I1 and the second signal I2 received by the input interface 131 after the compression of the biological tissue T is released. The second difference value ΔAp2 may be acquired as a difference value at any time point during the period after time point t3 in FIG. 2, or may be acquired as a statistical value of difference values ​​during any interval during the period. Examples of statistical values ​​include an average value, a median value, and a mode value.

[0042] In order to acquire the first difference value ΔAp1 and the second difference value ΔAp2 at appropriate timing, the processor 132 needs to recognize that the biological tissue T is being compressed.

[0043] When compression is performed manually by the user, the pulse oximeter 10 may notify the user of the timing of starting and releasing compression through a notification mechanism (not shown). The notification may be provided through at least one of a visual notification, an audible notification, and a tactile notification. The processor 132 may output a control signal for controlling the operation of the notification mechanism from the output interface 133. The processor 132 may recognize the output timing of the control signal in association with the compression period.

[0044] When compression is performed by a device such as an actuator (not shown), the processor 132 can output a control signal for controlling the operation of the actuator from the output interface 133. The processor 132 can recognize the output timing of the control signal in association with the compression period.

[0045] Alternatively, the start and end of compression may be determined based on whether the amount of change in the acquired difference value ΔA exceeds a threshold value.

[0046] Subsequently, the processor 132 is configured to calculate the difference between the first difference value ΔAp1 and the second difference value ΔAp2 as ΔAb. ΔAb = ΔAp2 - ΔAp1 (4)

[0047] 3, the biological tissue T includes blood Tb and tissue other than blood To. Because blood Tb is removed by compression, the first difference value ΔAp1 reflects the attenuation of the tissue other than blood To. On the other hand, because blood Tb returns when compression is released, the second difference value ΔAp2 reflects both the attenuation of the blood Tb and the attenuation of the tissue other than blood To.

[0048] Because the oxygen saturation of blood Tb changes from moment to moment, the attenuation also changes. However, the first difference value ΔAp1 does not fluctuate because it excludes the influence of blood Tb. On the other hand, the second difference value ΔAp2 fluctuates according to changes in the oxygen saturation of blood Tb. Therefore, the difference value ΔAb between the first difference value ΔAp1 and the second difference value ΔAp2 can be an index that more accurately reflects changes in the oxygen saturation of blood Tb.

[0049] In addition, since the unchanging first difference value ΔAp1 can be treated as a reference value, once compression of the biological tissue T is performed, the indicator can be continuously monitored by subsequently intermittently or continuously acquiring the second difference value ΔAp2.

[0050] To achieve the above-described effects, no special device or mechanism needs to be added to the pulse oximeter 10. Therefore, an improved indicator of the oxygen saturation of blood in living tissue can be provided in a simple manner.

[0051] 1, the pulse oximeter 10 may include an output device 14. The processor 132 of the processing device 13 outputs, from the output interface 133, an output control signal OC that causes the output device 14 to output information indicating the difference value ΔAb as the acquired index.

[0052] The output device 14 is configured to output information indicating the difference value ΔAb based on the output control signal OC. The information may be visually presented using at least one of text, a mark, and a color corresponding to the difference value ΔAb. The visual presentation of the information may be provided as an image displayed on a display or as printed matter. Additionally or alternatively, the information may be audibly presented through a speaker.

[0053] Alternatively, output device 14 may be a data output device that outputs other indices or biological information for processing to acquire the information. The processing may be performed within pulse oximeter 10 or may be performed in an external device separate from pulse oximeter 10.

[0054] As illustrated in FIG. 1, the input interface 131 of the processing device 13 may be configured to receive, from a user interface (not shown), a measurement signal M corresponding to a blood hemoglobin concentration value measured for a subject.

[0055] In this case, the processor 132 is configured to obtain the first light attenuation A1 and the second light attenuation A2 based on the measurement signal M.

[0056] The Hb value, which indicates the hemoglobin concentration in blood and is included in the above-described formulas (1) and (2), is a commonly used statistical constant. However, the actual hemoglobin concentration may, strictly speaking, take a value different from the constant. The processor 132 according to this example obtains the attenuation A1 of the first light and the attenuation A2 of the second light by using the hemoglobin concentration value corresponding to the measurement signal M as the Hb value in formulas (1) and (2).

[0057] With this configuration, the actual hemoglobin concentration in the blood, which may vary depending on the subject and their physical condition, can be reflected in the difference value ΔAb as the acquired index, thereby improving the accuracy of the index.

[0058] Next, another example of processing executed by the processor 132 of the processing device 13 will be described with reference to Fig. 4. In this example, the processor 132 acquires an index corresponding to the amount of blood contained in the biological tissue T.

[0059] Specifically, the processor 132 acquires an attenuation A11 of the first light during the period based on the first signal I1 received by the input interface 131 during compression of the biological tissue T. The attenuation A11 is an example of a first attenuation. Because blood is removed from the biological tissue T during compression, the attenuation A11 is substantially expressed by the following equation based on an analogy with equation (1): A11=At11 (5) At11: Primary light attenuation from tissues other than blood during compression

[0060] The attenuation A11 may be obtained as a measurement value at any time during the period from time t1 to time t2 in Fig. 2, or as a statistical value of measurements at any interval during that period. Examples of statistical values ​​include an average value, a median value, and a mode value.

[0061] In addition, the processor 132 acquires an attenuation A12 of the first light during the period based on the first signal I1 received by the input interface 131 after the compression of the biological tissue T is released. The attenuation A12 is an example of a second attenuation. The attenuation A12 is expressed by the following equation based on analogy with equation (1). A12=Ab12+At12 (6) Ab12: Primary light attenuation from blood after pressure release At12: First light attenuation from tissues other than blood after compression release

[0062] The attenuation A12 may be obtained as a measurement value at any time point in the period after time point t3 in Fig. 2, or as a statistical value of measurement values ​​in any section in the period. Examples of statistical values ​​include an average value, a median value, and a mode value.

[0063] Next, the processor 132 calculates a difference value ΔA1 between the light attenuation A11 and the light attenuation A12. The difference value ΔA1 is expressed by the following equation. ΔA1=A12-A11=Ab12+At12-At11 (7) Since the attenuation of the first light originating from tissues other than blood does not substantially change during compression and after compression is released, the difference value ΔA1 substantially represents the attenuation of the first light originating from blood after compression is released (ΔA1 ≒ Ab12).

[0064] As illustrated in Figure 4, biological tissue T includes blood Tb and tissue other than blood To. Because blood Tb is removed by compression, attenuation A11 reflects the attenuation of the tissue other than blood To. On the other hand, because blood Tb returns when compression is released, attenuation A12 reflects both the attenuation of blood Tb and the attenuation of the tissue other than blood To.

[0065] Since the amount of blood changes from moment to moment, the attenuation also changes. However, as illustrated in FIG. 4, the attenuation A11 does not fluctuate because it excludes the influence of blood Tb. On the other hand, the attenuation A12 fluctuates according to changes in the amount of blood Tb. Therefore, the difference ΔA1 between the attenuation A11 and the attenuation A12 can be an index that more accurately reflects changes in the amount of blood Tb.

[0066] In addition, since the constant attenuation A11 can be treated as a reference value, once compression of the biological tissue T is performed, the indicator can be continuously monitored by subsequently acquiring the attenuation A12 intermittently or continuously.

[0067] To achieve the above-described effects, no special device or mechanism needs to be added to the pulse oximeter 10. Therefore, an improved indicator of the amount of blood in living tissue can be provided in a simple manner.

[0068] If continuous monitoring is not required, the processor 132 may acquire the attenuation A10 of the first light during the period before compression of the biological tissue T (between time t0 and time t1 in FIG. 2) based on the first signal I1 received by the input interface 131. The attenuation A10 is also an example of the second attenuation. The attenuation A10 is expressed by the following equation: A10=Ab10+At10 (8) Ab10: Primary light attenuation due to blood before compression At10: First light attenuation from tissues other than blood before compression

[0069] The attenuation A10 may be obtained as a measurement value at any time during the period from time t0 to time t1 in Fig. 2, or as a statistical value of measurements at any interval during that period. Examples of statistical values ​​include the average value, median value, and mode value.

[0070] Next, the processor 132 calculates a difference value ΔA1′ between the light attenuation A10 and the light attenuation A11. The difference value ΔA1′ is expressed by the following equation. ΔA1'=A10-A11=Ab10+At10-At11 (9) Since the attenuation of the first light originating from tissues other than blood does not substantially change before and during compression, the difference value ΔA1′ substantially represents the attenuation of the first light originating from blood after compression is released (ΔA1′≒Ab12). Therefore, the difference value ΔA1′ can also be an index corresponding to the amount of blood contained in the biological tissue T.

[0071] In this example, the processor 132 may be configured to obtain the attenuation A12 based on the measurement signal M illustrated in Fig. 1. Similar to the example described with reference to equation (1), the processor 132 obtains the attenuation A12 by using the value of the hemoglobin concentration corresponding to the measurement signal M as the value of Hb that may be included in the term Ab12 in equation (6).

[0072] With this configuration, the actual hemoglobin concentration in the blood, which may vary depending on the subject and their physical condition, can be reflected in the difference value ΔA1 as the acquired index, thereby improving the accuracy of the index.

[0073] When the compression of the biological tissue T performed to acquire the difference value ΔA1 is released, the capillary refill time (CRT) of the biological tissue T can be determined based on the change over time in the difference value ΔA shown in Fig. 2. Specifically, the CRT is determined as the period from time t2 when the compression is released to time t3 when the transmitted light intensity can be considered to have returned to its original level. The difference value ΔA1 and CRT acquired in conjunction with the compression of the biological tissue T are referred to as the reference difference value ΔA1r and the reference CRT (rCRT).

[0074] The processor 132 can be configured to estimate the value of CRT based on the difference value ΔA1 as an index continuously acquired after compressing the biological tissue T. Specifically, the estimated value of CRT (eCRT) is calculated by the following equation. eCRT = (ΔA1r / ΔA1) × rCRT

[0075] According to this configuration, once compression of the biological tissue T is performed, the estimated value of CRT can be continuously obtained by subsequently intermittently or continuously acquiring the difference value ΔA1. In other words, the estimated value of CRT can be continuously monitored without repeatedly compressing the biological tissue T.

[0076] The processor 132 may be configured to cause the pulse oximeter 10 to issue a notification urging the user to acquire specific biological information based on the difference value ΔA1 as an index acquired as described above. As an example, if it is determined that the acquired difference value ΔA1 is not within a predetermined threshold range, a notification may be issued urging the user to reacquire CRT while compressing the biological tissue T.

[0077] With this configuration, when the difference value ΔA1, which is an indicator obtained without compressing the subject's biological tissue T, is determined to be abnormal, it can be used as an opportunity to obtain information to understand the subject's current condition.

[0078] In this case, the processor 132 outputs an output control signal OC that causes the output device 14 to output information indicating the estimated CRT from the output interface 133. The output device 14 outputs the information visually or audibly based on the output control signal OC.

[0079] The processor 132 of the processing device 13 having the various functions described above may be realized by at least one general-purpose microprocessor operating in cooperation with at least one general-purpose memory. Examples of the general-purpose microprocessor include a CPU, an MPU, and a GPU. Examples of the general-purpose memory include a ROM and a RAM. In this case, a computer program for executing the above-described processes may be stored in the ROM. The ROM is an example of a non-transitory computer-readable medium on which a computer program is stored. The general-purpose microprocessor specifies at least a portion of the program stored in the ROM, expands it in the RAM, and executes the above-described processes in cooperation with the RAM. The computer program may be pre-installed in the general-purpose memory, or may be downloaded from an external server device via a communication network and then installed in the general-purpose memory. In this case, the external server device is an example of a non-transitory computer-readable medium on which a computer program is stored.

[0080] The processor 132 may be implemented by at least one dedicated integrated circuit capable of executing the computer program, such as a microcontroller, an ASIC, or an FPGA. In this case, the computer program is pre-installed in a memory element included in the dedicated integrated circuit. The memory element is an example of a computer-readable medium on which a computer program is stored. The processor 132 may also be implemented by a combination of a general-purpose microprocessor and a dedicated integrated circuit.

[0081] The configurations described above are merely examples for facilitating understanding of the present disclosure. Each configuration example may be appropriately modified or combined with other configuration examples without departing from the spirit of the present disclosure.

[0082] 4, in which an index corresponding to the amount of blood contained in the biological tissue T is acquired, the first light having a first wavelength λ1 of 940 nm is used. With this configuration, the first light can be used in common with the example in which an index corresponding to the oxygen saturation level of the biological tissue T is acquired, as described with reference to FIG.

[0083] However, particularly when only an index corresponding to blood volume needs to be obtained, the first wavelength λ1 can be appropriately selected from a wavelength range in which the difference between the absorption coefficients of oxygenated hemoglobin and deoxygenated hemoglobin is relatively small, such as from 800 nm to 950 nm.

[0084] In the above embodiment, the pulse oximeter 10 has a built-in light emitting device 11 and a built-in light receiving device 12. This configuration can improve the portability of the pulse oximeter capable of obtaining various indices.

[0085] However, pulse oximetry system 20 may be configured as illustrated in Fig. 5. Pulse oximetry system 20 includes probe 21 and pulse oximeter 22. Probe 21 and pulse oximeter 22 are communicatively connected. Pulse oximetry system 20 is an example of a biological information processing system.

[0086] The probe 21 is configured to be attachable to the biological tissue T of a subject. The probe 21 includes the light-emitting device 11 and the light-receiving device 12 described with reference to Fig. 1. The pulse oximeter 22 includes the processing device 13 and the output device 14 described with reference to Fig. 1.

[0087] In each of the embodiments described so far, the processing device 13 is mounted on a pulse oximeter. However, the processing device 13 may be mounted on a device capable of data communication with the pulse oximeter. In this case, the pulse oximeter includes a communication device for data communication with the processing device 13. The first signal I1 and the second signal I2 output from the light receiving device 12 are transmitted to the processing device 13 by the communication device. The processing device 13 executes the various processes described above and transmits an output control signal OC to the pulse oximeter. Upon receiving the output control signal OC, the pulse oximeter outputs information indicating the acquired index from the output device 14.

[0088] The configurations listed below also constitute part of this disclosure. Item 1: a light emitting device that emits light having a wavelength in the range of 800 nm to 950 nm; a light receiving device that outputs a signal corresponding to the intensity of the light transmitted through the biological tissue of the subject; a processor that receives the signal; It is equipped with The processing device includes: obtaining a first attenuation of the light based on the signal during compression of the biological tissue; obtaining a second attenuation of the light based on the signal before compression of the biological tissue or after compression of the biological tissue is released; obtaining an index corresponding to the amount of blood contained in the biological tissue based on a difference between the first attenuation and the second attenuation; Biometric information processing system. Item 2: The processing device includes: receiving a measurement signal corresponding to a blood hemoglobin concentration value measured for the subject; correcting the indicator based on the measurement signal; Item 1. A biological information processing system according to item 1. Item 3: The processing device estimates a capillary refill time of the biological tissue based on the index. Item 3. The biological information processing system according to item 1 or 2. Item 4: the processing device determines whether or not it is necessary to acquire specific biological information from the subject based on the index. 4. The biological information processing system according to any one of items 1 to 3. [Explanation of symbols]

[0089] 10: pulse oximeter, 11: light emitting device, 12: light receiving device, 13: processing device, 131: input interface, 132: processor, 20: pulse oximetry system, I1: first signal, I2: second signal, M: measurement signal, T: biological tissue, λ1: first wavelength, λ2: second wavelength, ΔA1: difference value as index, ΔA11, ΔA12: attenuation, ΔAb: difference value as index, ΔAp1: first difference value, ΔAp2: second difference value

Claims

1. a light emitting device that emits first light having a first wavelength at which the absorption coefficient of oxygenated hemoglobin is greater than that of deoxygenated hemoglobin, and second light having a second wavelength at which the absorption coefficient of deoxygenated hemoglobin is greater than that of oxygenated hemoglobin; a light receiving device that outputs a first signal and a second signal corresponding to the intensity of the first light and the intensity of the second light, respectively, that have passed through a biological tissue of a subject; a processing device that receives the first signal and the second signal; It is equipped with The processing device includes: obtaining a first difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal during compression of the biological tissue; acquiring a second difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal after the compression of the biological tissue is released; obtaining an index corresponding to the oxygen saturation level of the blood contained in the biological tissue based on the difference between the first difference value and the second difference value; Biometric information processing system.

2. The processing device includes: receiving a measurement signal corresponding to a blood hemoglobin concentration value measured for the subject; obtaining an attenuation degree of the first light and an attenuation degree of the second light based on the measurement signal; The biological information processing system according to claim 1 .

3. a light emitting device that emits light having a wavelength in the range of 800 nm to 950 nm; a light receiving device that outputs a signal corresponding to the intensity of the light transmitted through the biological tissue of the subject; a processor that receives the signal; It is equipped with The processing device includes: obtaining a first attenuation of the light based on the signal during compression of the biological tissue; obtaining a second attenuation of the light based on the signal before compression of the biological tissue or after compression of the biological tissue is released; obtaining an index corresponding to the amount of blood contained in the biological tissue based on a difference between the first attenuation and the second attenuation; Biometric information processing system.

4. The processing device includes: receiving a measurement signal corresponding to a blood hemoglobin concentration value measured for the subject; correcting the indicator based on the measurement signal; The biological information processing system according to claim 3 .

5. The processing device estimates a capillary refill time of the biological tissue based on the index. The biological information processing system according to claim 3 .

6. the processing device determines whether or not it is necessary to acquire specific biological information from the subject based on the index. The biological information processing system according to claim 3 .

7. an interface that receives a first signal corresponding to the intensity of first light having a first wavelength at which the absorption coefficient of oxygenated hemoglobin passing through biological tissue of the subject is greater than the absorption coefficient of deoxygenated hemoglobin, and a second signal corresponding to the intensity of second light having a second wavelength at which the absorption coefficient of deoxygenated hemoglobin passing through the biological tissue is greater than the absorption coefficient of oxygenated hemoglobin; a processor; It is equipped with The processor: obtaining a first difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal during compression of the biological tissue; acquiring a second difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal after the compression of the biological tissue is released; obtaining an index corresponding to the oxygen saturation level of the blood contained in the biological tissue based on the difference between the first difference value and the second difference value; Processing equipment.

8. A computer program executable by a processor installed in a processing device, When executed, the processing device: receiving a first signal corresponding to the intensity of first light having a first wavelength at which the absorption coefficient of oxygenated hemoglobin passing through the biological tissue of the subject is greater than the absorption coefficient of deoxygenated hemoglobin, and a second signal corresponding to the intensity of second light having a second wavelength at which the absorption coefficient of deoxygenated hemoglobin passing through the biological tissue is greater than the absorption coefficient of oxygenated hemoglobin; obtaining a first difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal during compression of the biological tissue; acquiring a second difference value between the attenuation of the first light and the attenuation of the second light based on the first signal and the second signal after the compression of the biological tissue is released; obtaining an index corresponding to the oxygen saturation level of the blood contained in the biological tissue based on the difference between the first difference value and the second difference value; Computer program.

9. an interface that receives a signal corresponding to the intensity of light having a wavelength in the range of 800 nm to 950 nm that has passed through the biological tissue of the subject; a processor; It is equipped with The processor: obtaining a first attenuation of the light based on the signal during compression of the biological tissue; obtaining a second attenuation of the light based on the signal before compression of the biological tissue or after compression of the biological tissue is released; obtaining an index corresponding to the amount of blood contained in the biological tissue based on a difference between the first attenuation and the second attenuation; Processing equipment.

10. A computer program executable by a processor installed in a processing device, When executed, the processing device: receiving a signal corresponding to the intensity of light having a wavelength in the range of 800 nm to 950 nm that has passed through the biological tissue of the subject; obtaining a first attenuation of the light based on the signal during compression of the biological tissue; obtaining a second attenuation of the light based on the signal before compression of the biological tissue or after compression of the biological tissue is released; obtaining an index corresponding to the amount of blood contained in the biological tissue based on a difference between the first attenuation and the second attenuation; Computer program.

Images