MONITOR DEVICE, BIOLOGICAL SIGNAL PROCESSING APPARATUS, AND COMPUTER PROGRAM

Abstract

To suppress deterioration in estimation accuracy of pulse fundamental frequency resulting from a body motion, etc. of a subject.SOLUTION: A reception unit 111 receives a first photoelectric pulse wave signal PS1 acquired by irradiation of a first light including a first wavelength onto the body of a subject 20, and a heartbeat signal HS corresponding to the heartbeat of the subject 20. A processing unit 112 calculates a heartbeat fundamental frequency fh corresponding to a heart rate of the subject 20 on the basis of the heartbeat signal HS, and by comparing the heartbeat fundamental frequency fh to a frequency component of the first photoelectric pulse wave signal PS1, estimates pulse fundamental frequency fp of the subject 20. An information provision unit 12 provides information acquired on the basis of the pulse fundamental frequency fp.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a monitoring device that provides information obtained based on a fundamental frequency of a subject's pulse. The present invention also relates to a biosignal processing device that processes a photoplethysmographic signal and a heart rate signal to estimate the fundamental frequency, and a computer program executable by a processing unit of the biosignal processing device. [Background technology]

[0002] Patent Document 1 discloses an apparatus for calculating the pulse rate of a subject based on a photoelectric pulse wave signal obtained from the subject. In calculating the pulse rate, the frequency components of the photoelectric pulse wave signal are analyzed based on a previously calculated pulse rate, and the fundamental pulse frequency is estimated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-122552 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to suppress a decrease in the estimation accuracy of the pulse fundamental frequency caused by the subject's body movement or the like. [Means for solving the problem]

[0005] One aspect of the present invention to achieve the above object is a monitor device, comprising: a receiving unit that receives a first photoplethysmographic signal obtained by irradiating a body of a subject with a first light having a first wavelength and a heartbeat signal corresponding to a heartbeat of the subject; a processing unit that calculates a fundamental heart rate frequency corresponding to the heart rate of the subject based on the heart rate signal, and estimates a fundamental pulse frequency of the subject by comparing the fundamental heart rate frequency with a frequency component of the first photoplethysmographic signal; an information providing unit that provides information acquired based on the pulse fundamental frequency; It is equipped with:

[0006] One aspect of the present invention to achieve the above object is a biological signal processing device, comprising: a receiving unit that receives a first photoplethysmographic signal obtained by irradiating a body of a subject with a first light having a first wavelength and a heartbeat signal corresponding to a heartbeat of the subject; a processing unit that calculates a fundamental heart rate frequency corresponding to the heart rate of the subject based on the heart rate signal, and estimates a fundamental pulse frequency of the subject by comparing the fundamental heart rate frequency with a frequency component of the first photoplethysmographic signal; It is equipped with:

[0007] One aspect of the present invention to achieve the above object is a computer program executable by a processing unit of a biological signal processing device, By executing the above, the biological signal processing device receiving a first photoplethysmographic signal obtained by irradiating a body of the subject with a first light having a first wavelength; receiving a heart rate signal corresponding to a heart rate of the subject; calculating a fundamental heart rate frequency corresponding to the heart rate of the subject based on the heart rate signal; The fundamental heart frequency is compared with the frequency components of the first photoplethysmographic signal to estimate the fundamental pulse frequency of the subject.

[0008] When the noise component included in the first photoelectric pulse wave signal is relatively small, the frequency component of the first photoelectric pulse wave signal has a prominent single peak frequency corresponding to the pulsating component, and this frequency can be regarded as the fundamental pulse frequency of the subject. However, when a relatively large noise component is superimposed on the first photoelectric pulse wave signal due to the subject's body movement, the frequency component of the first photoelectric pulse wave signal may include multiple peak frequencies. In this case, it becomes necessary to estimate the fundamental pulse frequency by some method.

[0009] In the configurations according to the above aspects, based on the idea that the subject's heart rate and pulse rate are highly likely to be correlated, the pulse fundamental frequency is estimated based on a comparison between the heart rate fundamental frequency calculated based on the heart rate signal and the frequency component of the first photoplethysmographic signal, thereby making it possible to suppress a decrease in the estimation accuracy of the pulse fundamental frequency caused by the subject's body movement, etc. [Brief description of the drawings]

[0010] [Figure 1] 2 illustrates an example of a functional configuration of a monitor device according to an embodiment. [Diagram 2] 2 illustrates an example of a flow of processing executed by the processing unit of FIG. 1. [Diagram 3] 2 is a diagram for explaining a process executed by a processing unit in FIG. 1; [Figure 4] 2 is a diagram for explaining a process executed by a processing unit in FIG. 1; [Diagram 5] 2 is a diagram for explaining a process executed by a processing unit in FIG. 1; [Figure 6] 2 is a diagram for explaining a process executed by a processing unit in FIG. 1; [Figure 7] 2 shows another example of the configuration of the monitor device and the biological signal processing device of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. In each drawing, the scale is appropriately changed so that each element to be described can be clearly seen.

[0012] 1 illustrates an example of a functional configuration of a monitoring device 10 according to an embodiment. The monitoring device 10 is a device that provides a user with information acquired based on a fundamental pulse frequency of a subject 20. The monitoring device 10 includes a biological signal processing device 11 and an information providing unit 12.

[0013] The biological signal processing device 11 is configured to estimate a fundamental pulse frequency based on information related to a pulse wave and a heartbeat acquired from a subject 20. The biological signal processing device 11 includes a receiving unit 111 and a processing unit 112.

[0014] Receiving unit 111 is configured as an interface that receives first photoelectric pulse wave signal PS1 and heartbeat signal HS. Each of first photoelectric pulse wave signal PS1 and heartbeat signal HS may be an analog signal or a digital signal. When each of first photoelectric pulse wave signal PS1 and heartbeat signal HS is an analog signal, receiving unit 111 is provided with an appropriate conversion circuit including an A / D converter.

[0015] The first photoelectric pulse wave signal PS1 is acquired through a probe 30 attached to the subject 20. The probe 30 includes a light-emitting element and a light-receiving element. The light-emitting element irradiates the body of the subject 20 with infrared light. The infrared light is an example of the first light. The infrared light that has passed through the body or has been reflected by the body is incident on the light-receiving element. The light-receiving element is sensitive to the infrared light, and outputs a first photoelectric pulse wave signal PS1 having an amplitude corresponding to the intensity of the incident light.

[0016] Since infrared light is absorbed by blood flowing through blood vessels in the body, the intensity of the infrared light incident on the light receiving element is lower than the intensity of the infrared light emitted from the light emitting element. When blood vessels pulsate with the beating of the heart, the optical path length related to absorption changes, and the intensity of the light incident on the light receiving element also changes. That is, the amplitude of the first photoelectric pulse wave signal PS1 increases and decreases in response to the pulsation of the blood vessels. The ratio of the intensity of the light emitted from the light emitting element to the intensity of the light incident on the light receiving element also changes, and this ratio may be made to correspond to the amplitude of the first photoelectric pulse wave signal PS1.

[0017] The heartbeat signal HS is a signal that exhibits a change in amplitude over time that corresponds to the heartbeat of the subject 20. In this example, the heartbeat signal HS corresponds to an electrocardiogram signal output from an electrocardiograph 40 connected to the body of the subject 20.

[0018] The processing performed by the processing unit 112 will be described with reference to FIGS.

[0019] Processing unit 112 acquires first photoelectric pulse wave signal PS1 over a predetermined period of time (STEP 1). As described above, first photoelectric pulse wave signal PS1 is acquired via receiving unit 111. In Fig. 3, the acquired first photoelectric pulse wave signal PS1 is illustrated by a solid line.

[0020] Next, processing unit 112 performs frequency analysis on the acquired first photoelectric pulse wave signal PS1 (STEP 2). Fig. 4 illustrates a frequency spectrum obtained as a result of performing frequency analysis on first photoelectric pulse wave signal PS1 of Fig. 3.

[0021] The acquired first photoplethysmographic signal PS1 is superimposed with a respiratory noise component indicated by a dashed line in Fig. 3. The respiratory noise is generated due to bodily movement associated with breathing of subject 20 and changes in the amount of blood in the blood vessels, and is superimposed on a pure vascular pulsation component. Since the fundamental frequency of the respiratory noise component and the fundamental frequency of the pulsation component are different, a peak frequency f1 reflecting the respiratory noise component and a peak frequency f2 reflecting the pulsation component appear in the frequency spectrum illustrated in Fig. 4.

[0022] 2, the processing unit 112 acquires the heartbeat signal HS at the same timing as the first photoelectric pulse wave signal PS1 (STEP 3). As described above, the heartbeat signal HS is acquired via the receiving unit 111.

[0023] Next, the processing unit 112 calculates a fundamental heart rate frequency fh corresponding to the heart rate of the subject 20 based on the acquired heart rate signal HS (STEP 4). A well-known method can be used for the calculation of the fundamental heart rate fh from the electrocardiogram waveform.

[0024] 2, a first set of processing in STEP 1 and a subsequent processing in STEP 2, and a second set of processing in STEP 3 and a subsequent processing in STEP 4 may be performed at least partially in parallel. Also, the second set of processing may be started first, and the first set of processing may be started subsequently.

[0025] Next, the processing unit 112 estimates the fundamental pulse frequency of the subject 20 (STEP 5). Specifically, the processing unit 112 compares the fundamental heartbeat frequency fh calculated in STEP 4 with the frequency components (frequency spectrum) of the first photoelectric pulse wave signal PS1 acquired in STEP 2, and estimates the peak frequency closest to the fundamental heartbeat frequency fh as the fundamental pulse frequency.

[0026] 4, the fundamental heartbeat frequency fh calculated in STEP 4 is superimposed on the frequency spectrum of the first photoelectric pulse wave signal PS1 acquired in STEP 2. In this example, the peak frequency f2 is closest to the fundamental heartbeat frequency fh. Therefore, the peak frequency f2 is estimated to be the fundamental pulse frequency fp of the subject 20.

[0027] When the noise component contained in first photoelectric pulse wave signal PS1 is relatively small, the frequency components of first photoelectric pulse wave signal PS1 have a single prominent peak frequency corresponding to the pulsating component, and this frequency can be regarded as the fundamental pulse frequency of subject 20. However, when a relatively large noise component is superimposed on first photoelectric pulse wave signal PS1 due to body movement of subject 20 or the like, the frequency components of first photoelectric pulse wave signal PS1 may include multiple peak frequencies. In this case, it becomes necessary to estimate the fundamental pulse frequency using some method.

[0028] In this embodiment, based on the idea that there is a high probability that the heart rate and pulse rate of the subject 20 are correlated, the pulse fundamental frequency is estimated based on a comparison between the heart rate fundamental frequency fh calculated based on the heart rate signal HS and the frequency components of the first photoelectric pulse wave signal PS1. This makes it possible to suppress a decrease in the estimation accuracy of the pulse fundamental frequency caused by the body movement of the subject 20, etc.

[0029] For example, when a process is applied in which the peak frequency with the highest spectral intensity is estimated as the fundamental pulse frequency for the frequency spectrum illustrated in Fig. 4, the fundamental pulse frequency is estimated based on the peak frequency f1 corresponding to the respiratory noise component. On the other hand, according to the method of this embodiment, the fundamental pulse frequency can be estimated based on the peak frequency f2 corresponding to the pulsating component.

[0030] In addition, when estimating the fundamental pulse frequency, it is preferable to add a condition that "the peak frequency is closest to the fundamental heart rate frequency fh" and that "the difference between the peak frequency and the fundamental heart rate frequency fh is less than a predetermined value." This condition reduces the possibility that the estimation will be performed based on a peak frequency corresponding to a noise component that is accidentally obtained near the fundamental heart rate frequency fh in a situation where no significant peak frequency corresponding to a pulsating component is obtained.

[0031] In this embodiment, the processing unit 112 uses an index called an "RR interval" in an electrocardiogram signal to estimate the fundamental pulse frequency. The "RR interval" represents the interval from a specific R wave to the next R wave that appears in the electrocardiogram signal.

[0032] Specifically, the processing unit 112 can be configured to calculate the fundamental cardiac frequency fh when a predetermined number N or more of valid RR intervals are included in the electrocardiogram signal within a predetermined time T. The predetermined time T is, for example, 8 seconds. The predetermined number N is, for example, 5.

[0033] FIG. 5 illustrates an example of an electrocardiogram signal acquired from a subject. A number of vertical bars aligned along the time axis represent QRS waves. In the figure, RR intervals determined to be valid are assigned a number (#). In the electrocardiogram signal according to this example, six valid RR intervals are included within a predetermined time T, so the processing unit 112 calculates the fundamental heartbeat frequency fh based on the heartbeat signal HS corresponding to the electrocardiogram signal.

[0034] Specifically, the heart rate corresponding to the average value of N or more RR intervals that are determined to be valid is calculated, and the fundamental heart rate frequency fh is calculated based on the reciprocal. It is preferable to obtain the average value of (N-2) or more RR intervals excluding the maximum and minimum values ​​from the multiple RR intervals obtained. In this case, the influence of noise can be further suppressed.

[0035] Whether a particular RR interval is valid may be determined based on a number of conditions listed below. Specifically, if all of the following conditions are satisfied for a particular RR interval, the RR interval is determined to be valid. Condition 1: The RR interval is not associated with arrhythmia. Condition 2: The RR interval is included in a predetermined value range. Condition 3: The fluctuation of the RR interval is less than a predetermined value.

[0036] An algorithm for determining arrhythmia based on RR intervals is generally implemented in the electrocardiograph 40. Therefore, the heartbeat signal HS may include information relating to the association with arrhythmia that is added every time an RR interval is detected. The processing unit 112 may determine whether Condition 1 is satisfied by referring to the information.

[0037] The predetermined value range related to condition 2 is determined as an RR interval corresponding to possible values ​​of the heart rate of a living body (eg, 30 to 300).

[0038] The "fluctuation" according to condition 3 is calculated as a ratio of an RR interval acquired at a certain time point to an RR interval acquired immediately before that time point. For example, in the case of an RR interval acquired at time point t3 in Fig. 5, the ratio to the RR interval acquired at time point t2 is calculated. The processing unit 122 determines whether the value of the ratio is less than a predetermined value.

[0039] In the example shown in FIG. 5, the RR intervals acquired at time points t4, t5, and t6 do not satisfy any of the above conditions 1 to 3, and are determined by the processing unit 112 to be invalid.

[0040] According to such a configuration, it is possible to eliminate information that does not contribute to the calculation of an appropriate heartbeat fundamental frequency fh, thereby suppressing a decrease in the estimation accuracy of the pulse fundamental frequency caused by noise.

[0041] The processing unit 112 does not perform the above process every time a predetermined time T elapses, but performs the above process while shifting the frame corresponding to the predetermined time T so as to allow overlap of the sections to be processed. For example, in the example shown in Fig. 5, the above process is performed for the predetermined time T including time points t0 to t9, and then the above process is performed for the predetermined time T including time points t1 to t10. The amount of movement (time) of the frame can be determined appropriately (for example, 1 second).

[0042] As illustrated in FIG. 2, the processing unit 112 acquires predetermined information related to the subject 20 based on the estimated pulse fundamental frequency (STEP 6), and provides the information to the user of the monitoring device 10 (STEP 7).

[0043] As an example of information related to the subject 20, a pulse rate can be calculated. In this case, as illustrated in FIG. 1, the biological signal processing device 11 can include a filter 113. The filter 113 is a digital filter that passes signals in a specific frequency band. In the following description, the specific frequency band, which is referred to as a filter band, is variable. The processing unit 112 sets the filter band of the filter 113 so as to include the pulse fundamental frequency fp estimated through the above processing.

[0044] After setting the filter frequency, processing unit 112 passes first photoelectric pulse wave signal PS1 received by receiving unit 111 through filter 113. In the example shown in Fig. 4, the band around peak frequency f2 of first photoelectric pulse wave signal PS1 passes through filter 113, and the band around peak frequency f1 is removed. As a result, a first photoelectric pulse wave signal PS1' is obtained in which frequency components other than the pulsating component have been reduced, as illustrated in Fig. 1.

[0045] The processing unit 112 calculates the pulse rate of the subject 20 based on the first photoplethysmographic signal PS1'. The calculation can be performed using a well-known method.

[0046] The biological signal processing device 11 includes an output unit 114. The output unit 114 is configured as an interface that outputs a control signal CS that causes the information providing unit 12 to provide the pulse rate of the subject 20 calculated as described above. The control signal CS may be an analog signal or a digital signal. When the control signal CS is an analog signal, the output unit 114 includes an appropriate conversion circuit including a D / A converter.

[0047] The information providing unit 12 that has received the control signal CS provides the calculated pulse rate to the user of the monitor device 10 using at least one of a visual method and an auditory method. For example, the information providing unit 12 may include a screen. The calculated pulse rate may be displayed on the screen. Visual information may be provided by a light-emitting device that emits light in a color corresponding to the pulse rate. For example, the information providing unit 12 may include a speaker. Sound corresponding to the calculated pulse rate may be output through the speaker.

[0048] According to the above-described configuration, the filter band of filter 113 is set based on the estimated pulse fundamental frequency fp while suppressing the influence of the body movement of subject 20 and the like, and the pulse rate of subject 20 is calculated based on first photoplethysmographic signal PS1' in which frequency components other than the pulsating component have been reduced by filter 113, thereby improving the accuracy of pulse rate calculation.

[0049] As another example of the information related to the subject 20, a portion of the first photoelectric pulse wave signal PS1 that corresponds to the pulse of the subject 20 can be identified. Specifically, a peak waveform portion that appears in the first photoelectric pulse wave signal PS1 at a period that corresponds to the fundamental pulse frequency fp is identified as the portion that corresponds to the pulse of the subject 20.

[0050] In this case, output unit 114 outputs a control signal CS that causes first photoelectric pulse wave signal PS1, to be displayed with annotations indicating the portions corresponding to the pulse, on the screen of information provider 12. In Fig. 6, the annotations are displayed as multiple vertical bars below the waveform of first photoelectric pulse wave signal PS1.

[0051] This configuration can assist the user in identifying the portion corresponding to the pulse of the subject 20 from the first photoplethysmographic signal PS1 on which noise components are superimposed. In particular, since annotation is provided based on the pulse fundamental frequency fp estimated while suppressing the effects of the body movement of the subject 20, the accuracy of identifying the portion corresponding to the pulse can be improved.

[0052] As another example of information related to the subject 20, whether the probe 30 is attached to the subject 20 can be determined.

[0053] Even if the probe 30 is not properly attached to the body of the subject 20, the first photoelectric pulse wave signal PS1 whose amplitude periodically increases and decreases may be output. The processing unit 112 compares the peak frequency appearing in the frequency spectrum of the first photoelectric pulse wave signal PS1 with the fundamental heartbeat frequency fh calculated based on the heartbeat signal HS. If no correlation is found between the two, it is highly likely that the increase and decrease in the amplitude of the first photoelectric pulse wave signal PS1 is caused not by pulsation but by the probe 30 not being properly attached to the body of the subject 20. Therefore, the processing unit 112 can determine whether the probe 30 is properly attached to the subject 20 based on the comparison result between the frequency component of the first photoelectric pulse wave signal PS1 and the fundamental heartbeat frequency fh.

[0054] The output unit 114 outputs a control signal CS for causing the information providing unit 12 to provide the result of the determination made by the processing unit 112. For example, upon receiving the control signal CS, the information providing unit 12 provides an alarm based on the determination result that the probe 30 is not properly attached to the user of the monitoring device 10 using at least one of a visual method and an auditory method. For example, the alarm may be displayed on a screen of the information providing unit 12. Visual information may be provided by a light-emitting device that emits light in a color corresponding to the alarm. Additionally or alternatively, a sound corresponding to the alarm may be output through a speaker of the information providing unit 12.

[0055] According to such a configuration, a determination is made as to whether the probe 30 is properly attached based on the estimated pulse fundamental frequency fp while suppressing the influence of the subject 20's body movements and the like, thereby improving the accuracy of the determination for encouraging the user to reattach the probe 30.

[0056] As another example of information related to the subject 20, percutaneous arterial oxygen saturation (SpO2) may be calculated. SpO2 corresponds to the concentration of oxygenated hemoglobin in the arterial blood of the subject 20. Oxygenated hemoglobin is an example of a light-absorbing substance in blood. In this case, as illustrated in FIG. 1, the probe 30 is configured to output a second photoplethysmographic signal PS2. The second photoplethysmographic signal PS2 is also received by the receiving unit 111.

[0057] Specifically, the probe 30 includes a light-emitting element that emits red light and a light-receiving element that is sensitive to red light. A light-receiving element that is sensitive to both infrared light and red light may be used in common. The red light is an example of the second light. The wavelengths of the infrared light and the red light are appropriately selected as two wavelengths that have different absorbances due to oxygenated hemoglobin. The wavelength of the infrared light is an example of the first wavelength. The wavelength of the red light is an example of the second wavelength. The light-receiving element outputs a second photoplethysmographic signal PS2 having an amplitude corresponding to the intensity of the incident light.

[0058] When blood vessels pulsate with the beating of the heart, the optical path length related to the absorption of red light changes, and the intensity of light incident on the light receiving element also changes. That is, the amplitude of the second photoelectric pulse wave signal PS2 increases or decreases in response to the pulsation of the blood vessels. The ratio of the intensity of light emitted from the light emitting element to the intensity of light incident on the light receiving element also changes, and this ratio may be made to correspond to the amplitude of the second photoelectric pulse wave signal PS2.

[0059] Processing unit 112 sets the filter band of filter 113 so as to include the estimated fundamental pulse frequency fp, and then passes second photoelectric pulse wave signal PS2 received by receiving unit 111 through filter 113. As a result, a second photoelectric pulse wave signal PS2' in which frequency components other than the pulsating component have been reduced is obtained.

[0060] Processing unit 112 calculates the SpO2 of subject 20 based on first photoelectric pulse wave signal PS1' and second photoelectric pulse wave signal PS2'. SpO2 is calculated using a well-known method based on the ratio of the amplitude of first photoelectric pulse wave signal PS1' to the amplitude of second photoelectric pulse wave signal PS2', which corresponds to the ratio of the received light intensity of red light to the received light intensity of infrared light at the light receiving element.

[0061] The output unit 114 outputs a control signal CS that causes the information providing unit 12 to provide the SpO2 of the subject 20 calculated as described above. The information providing unit 12 that receives the control signal CS provides the calculated SpO2 to the user of the monitor device 10 using at least one of a visual method and an auditory method. For example, the information providing unit 12 may include a screen. The calculated SpO2 may be displayed on the screen. Visual information may be provided by a light-emitting device that emits light in a color corresponding to the SpO2. For example, the information providing unit 12 may include a speaker. The calculated SpO2 or a sound corresponding to the SpO2 may be output through the speaker.

[0062] When calculating SpO2, changes in the attenuation of red light and infrared light associated with vascular pulsation may be taken into consideration. With the above-described configuration, the filter band of filter 113 is set based on the estimated pulse fundamental frequency fp while suppressing the effects of body movement of subject 20, and SpO2 of subject 20 is calculated based on first photoelectric pulse wave signal PS1' and second photoelectric pulse wave signal PS2' in which frequency components other than pulsation components have been reduced by filter 113, thereby improving the accuracy of SpO2 calculation.

[0063] The processing unit 112 having the various functions described above can be realized by a general-purpose microprocessor that operates in cooperation with a 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, the ROM can store a computer program that executes the above-mentioned processing. The ROM is an example of a non-transient computer-readable medium in which a computer program is stored. The general-purpose microprocessor specifies at least a part of the computer program stored on the ROM, deploys it on the RAM, and executes the above-mentioned processing in cooperation with the RAM. The above-mentioned computer program may be pre-installed in the general-purpose memory, or may be downloaded from an external server device 60 via a communication network 50 illustrated in FIG. 7 and installed in the general-purpose memory. In this case, the external server device 60 is an example of a non-transient computer-readable medium in which a computer program is stored.

[0064] The processing unit 112 having the various functions described above may be realized by a dedicated integrated circuit capable of executing the above computer program, such as a microcontroller, an ASIC, or an FPGA. In this case, the above computer program is pre-installed in a memory element included in the dedicated integrated circuit. The memory element is an example of a non-transitory computer-readable medium on which a computer program is stored. The processing unit 112 may also be realized by a combination of a general-purpose microprocessor and a dedicated integrated circuit.

[0065] The above-described embodiment is merely an example for facilitating understanding of the present invention. The configurations according to the above-described embodiment may be appropriately modified or improved without departing from the spirit and scope of the present invention.

[0066] In the above embodiment, the first photoelectric pulse wave signal PS1 generated using infrared light, which is known to have a relatively high resistance to noise caused by body movement, is the target of processing by the biological signal processing device 11. However, if necessary, the first photoelectric pulse wave signal PS1 generated using red light may also be the target of processing.

[0067] In the above embodiment, the SpO2 of the subject 20 is calculated using infrared light and red light. However, the at least two wavelengths used to calculate the SpO2 may both be infrared light or both be red light, as long as the ratio of the light absorption coefficient of blood differs depending on the oxygen saturation. Similarly, the at least two wavelengths used to calculate the concentration of other light absorbing substances in blood may be appropriately determined according to the light absorption characteristics of the light absorbing substances in blood. Examples of other light absorbing substances in blood may include not only substances generated in the body of the subject 20, such as carboxyhemoglobin and methemoglobin, but also dyes injected into blood vessels for the purpose of contrast examinations and the like.

[0068] In the above embodiment, the heartbeat signal HS is generated based on an electrocardiogram signal acquired through the electrocardiograph 40. In this case, as described above, it is advantageous in that information related to arrhythmia can be included in the heartbeat signal HS. Note that the electrocardiograph 40 may calculate the heart rate based on the electrocardiogram signal and generate the heartbeat signal HS corresponding to the calculated heart rate. Instead of the electrocardiogram signal, the heartbeat signal HS may be generated based on an invasive blood pressure signal acquired through a catheter. The amplitude of the invasive blood pressure signal also increases and decreases in response to the pulsation of the heart.

[0069] In the above embodiment, the biological signal processing device 11 is mounted on the monitoring device 10. However, the biological signal processing device 11 may be mounted on an external server device 60 capable of communicating with the monitoring device 10 via a communication network 50 illustrated in Fig. 7. The communication between the monitoring device 10 and the external server device 60 may be performed by wired communication or wireless communication. In this case, the monitoring device 10 is configured to include a communication interface for transmitting the first photoelectric pulse wave signal PS1, the second photoelectric pulse wave signal PS2, and the heartbeat signal HS to the external server device 60 and for receiving the control signal CS from the external server device 60. [Explanation of symbols]

[0070] 10: monitor device, 11: biosignal processing device, 111: reception unit, 112: processing unit, 113: filter, 12: information providing unit, 20: subject, 30: probe, HS: heartbeat signal, PS1: first photoplethysmogram signal, PS2: second photoplethysmogram signal, fh: heartbeat fundamental frequency, fp: pulse fundamental frequency

Claims

1. a receiving unit that receives a first photoplethysmographic signal obtained by irradiating a body of a subject with a first light having a first wavelength and a heartbeat signal corresponding to a heartbeat of the subject; a processing unit that calculates a fundamental heart rate frequency corresponding to the heart rate of the subject based on the heart rate signal, and estimates a frequency peak value of the first photoplethysmographic signal that is closest to the calculated fundamental heart rate frequency as the fundamental pulse frequency of the subject; an information providing unit that provides information acquired based on the pulse fundamental frequency; Equipped with the heart rate signal is based on an electrocardiogram signal obtained from the subject; The processing unit calculates the fundamental heart rate frequency when a predetermined number or more of valid R-R intervals are included in the electrocardiogram signal within a predetermined time period. Monitor device.

2. The processing unit determines that the RR interval is valid when the RR interval is not associated with arrhythmia, the RR interval is within a predetermined value range, and a fluctuation of the RR interval is less than a predetermined value.

2. The monitor device according to claim 1.

3. The heart rate signal includes information relating to an association with arrhythmia that is provided each time an R-R interval is detected.

3. The monitor device according to claim 2.

4. It has a filter that passes signals in a specific frequency band. the processing unit sets the frequency band so as to include the estimated fundamental pulse frequency, and calculates a pulse rate of the subject based on the first photoplethysmogram signal that has passed through the filter; and The information providing unit provides the calculated pulse rate as the information. A monitor device according to any one of claims 1 to 3.

5. It has a filter that passes signals in a specific frequency band. the receiving unit receives a second photoplethysmogram signal obtained by irradiating the body with second light including a second wavelength whose absorbance by a light-absorbing substance in blood of the subject is different from the first wavelength; the processing unit sets the frequency band so as to include the estimated fundamental pulse frequency, and calculates a concentration of the light-absorbing substance in the blood based on the first photoelectric pulse wave signal and the second photoelectric pulse wave signal that have passed through the filter; The monitor device according to claim 1 , wherein the information providing unit provides the calculated concentration of the light-absorbing substance in the blood as the information.

6. the processing unit identifies a portion of the first photoplethysmographic signal corresponding to the subject's pulse based on the estimated fundamental pulse frequency; and the information providing unit provides, as the information, the first photoplethysmographic signal in a visible form to which an annotation indicating a portion corresponding to the pulse has been added. A monitor device according to any one of claims 1 to 5.

7. When no correlation is found between the fundamental heartbeat frequency and a frequency peak value of the first photoelectric pulse wave signal, the processing unit determines that a probe for acquiring the first photoelectric pulse wave signal is not properly attached to the subject. The information providing unit provides a result of the judgment as the information. A monitor device according to any one of claims 1 to 6.

8. The first light is infrared light. A monitor device according to any one of claims 1 to 7.

9. a receiving unit that receives a first photoplethysmographic signal obtained by irradiating a body of a subject with a first light having a first wavelength and a heartbeat signal corresponding to a heartbeat of the subject; a processing unit that calculates a fundamental heart rate frequency corresponding to the heart rate of the subject based on the heart rate signal, and estimates a frequency peak value of the first photoplethysmographic signal that is closest to the calculated fundamental heart rate frequency as the fundamental pulse frequency of the subject; Equipped with the heart rate signal is based on an electrocardiogram signal obtained from the subject; The processing unit calculates the fundamental heart rate frequency when a predetermined number or more of valid R-R intervals are included in the electrocardiogram signal within a predetermined time period. Biosignal processing device.

10. A computer program executable by a processing unit of a biological signal processing device, By executing the above, the biological signal processing device receiving a first photoplethysmographic signal obtained by irradiating a body of the subject with a first light having a first wavelength; accepting a heartbeat signal based on an electrocardiogram signal obtained from the subject and corresponding to a heartbeat of the subject; calculating a fundamental heart rate frequency corresponding to the heart rate of the subject based on the heart rate signal; a frequency peak value of the first photoplethysmographic signal that is closest to the fundamental heart frequency is estimated as the fundamental pulse frequency of the subject; When a predetermined number of valid RR intervals are included in the electrocardiogram signal within a predetermined time period, the calculation of the cardiac fundamental frequency is performed. Computer program.

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