JP2019166150A - Biological information measurement device and biological information measurement program - Google Patents

Abstract

To notify measurement accuracy for biological information associated with oxygen circulation time.SOLUTION: When a biological information measurement device 10 measures a degree of oxygen saturation of a subject and measures a cardiac output from a waveform representing variation in the degree of oxygen saturation, the biological information measurement device notifies a degree of reliability D representing a degree of conformance or degree of non-conformance of the waveform of the degree of oxygen saturation relative to measurement of cardiac output in accordance with a conformance condition.SELECTED DRAWING: Figure 15

Description

  The present invention relates to a biological information measuring device and a biological information measuring program.

  Patent Document 1 discloses a signal acquisition unit that acquires an airflow signal that indicates a temporal change in respiratory airflow, an oxygen saturation signal that indicates a temporal change in oxygen saturation, a first time in the airflow signal, and the first A circulation time measuring device having a circulation time calculation unit for measuring the oxygen circulation time of blood based on a time difference from the second time in the oxygen saturation signal indicating an increase in oxygen saturation corresponding to resumption of breathing at one time Is disclosed.

Table 2015-190413

  2. Description of the Related Art Conventionally, development of a measurement method for measuring biological information using an oxygen circulation time indicating a time required for oxygen taken into the body to be transported to a predetermined site has been advanced.

  The oxygen circulation time is estimated from, for example, oxygen saturation. Therefore, when the measured oxygen saturation does not satisfy the conditions suitable for the measurement of biological information related to the oxygen circulation time, the biological information is compared with the case where the biological information is measured using the oxygen saturation satisfying the conditions. Information measurement accuracy may be reduced.

  However, in the measurement of biological information related to the oxygen circulation time so far, the biological information is measured regardless of whether or not the measured oxygen saturation satisfies a condition suitable for the measurement of biological information. Therefore, the measurement accuracy of the obtained biological information may vary.

  An object of this invention is to provide the biological information measuring device which can alert | report the measurement precision of the biological information relevant to oxygen circulation time, and a biological information measurement program.

  In order to achieve the above object, the biological information measuring apparatus according to claim 1 includes a measuring unit that measures a value representing an oxygen concentration in the blood of the measurement subject, and the value measured by the measuring unit. When performing measurement of biological information related to oxygen circulation time using a waveform representing a change, informing means for notifying an index representing the degree of conformity or nonconformity of the waveform with respect to the measurement of the biological information according to a predetermined condition, Prepare.

  In the invention described in claim 2, the waveform condition suitable for the measurement of the biological information is defined as the predetermined condition.

  According to a third aspect of the invention, the waveform condition that is not suitable for the measurement of the biological information is defined as the predetermined condition.

  According to a fourth aspect of the present invention, the predetermined condition includes the number of inflection points in the waveform, and the informing means according to the number of inflection points in the waveform according to the predetermined condition. The indicator is notified.

  In the invention according to claim 5, the magnitude of the value at the inflection point of the waveform is included in the predetermined condition, and the informing means at the inflection point of the waveform according to the predetermined condition. The indicator according to the magnitude of the value is notified.

  According to a sixth aspect of the invention, the predetermined condition includes the magnitude of the slope of the waveform, and the informing means provides the indicator according to the magnitude of the slope of the waveform according to the predetermined condition. Is notified.

  According to a seventh aspect of the present invention, the predetermined condition includes a degree of variation in the slope of the waveform, and the informing means provides the index according to the degree of variation in the inclination of the waveform according to the predetermined condition. Is notified.

  According to an eighth aspect of the present invention, the predetermined condition includes information related to an appearance position of an inflection point in the waveform, and the notifying unit generates an inflection point in the waveform according to the predetermined condition. The indicator according to the position is notified.

  According to the ninth aspect of the present invention, the predetermined condition is set for a plurality of periods divided by the breathing state of the measurement subject, and the notification means At least one of the indicators is notified.

  In the tenth aspect of the present invention, when the index indicates that the waveform is not suitable for the measurement of the biological information, the measurement unit stops measuring the value.

  An eleventh aspect of the invention includes an accepting unit that accepts an instruction from the subject or a measurer who measures the biological information of the subject, and the measuring unit measures the biological information by the accepting unit. When the instruction to stop the operation is accepted, the measurement of the value is stopped.

  The invention described in claim 12 comprises information measuring means for measuring the biological information using the waveform indicated by the index to be suitable for the measurement of the biological information.

  The invention of the biological information measurement program according to claim 13 causes a computer to function as each means of the biological information measurement device according to any one of claims 1 to 12.

  According to invention of Claim 1, 13, it has the effect that the measurement precision of the biometric information relevant to oxygen circulation time can be alert | reported.

  According to the second aspect of the present invention, when the change in the value representing the oxygen concentration satisfies a predetermined condition, the measured value representing the oxygen concentration is suitable for measurement of biological information related to the oxygen circulation time. Can be notified.

  According to the third aspect of the present invention, when the change in the value representing the oxygen concentration satisfies a predetermined condition, the measured value representing the oxygen concentration is not suitable for the measurement of biological information related to the oxygen circulation time. Can be notified.

  According to the fourth aspect of the invention, the measurement accuracy of the biological information related to the oxygen circulation time can be notified from the number of inflection points in the value representing the oxygen concentration.

  According to the fifth aspect of the present invention, the measurement accuracy of the biological information related to the oxygen circulation time can be notified from the magnitude of the inflection point in the value representing the oxygen concentration.

  According to the sixth aspect of the present invention, the measurement accuracy of the biological information related to the oxygen circulation time can be notified from the magnitude of the slope in the waveform of the value representing the oxygen concentration.

  According to the seventh aspect of the invention, the measurement accuracy of the biological information related to the oxygen circulation time can be notified from the degree of variation in the slope of the waveform of the value representing the oxygen concentration.

  According to the eighth aspect of the invention, the measurement accuracy of the biological information related to the oxygen circulation time can be notified from the appearance position of the inflection point in the waveform of the value representing the oxygen concentration.

  According to the ninth aspect of the present invention, the measurement accuracy of the biological information related to the oxygen circulation time can be improved as compared with the case where the same condition is used in a plurality of periods classified according to the respiratory state of the measurement subject. Has the effect.

  According to the tenth aspect of the present invention, there is an effect that it is possible to prevent measurement of the value of biological information that exceeds a predetermined measurement accuracy range.

  According to the eleventh aspect of the present invention, the measurement subject or the measurer of the biological information can select whether or not to stop the measurement of the biological information based on the content of the notified indicator. Have

  According to the twelfth aspect of the invention, it is possible to select a measurement result that is preferable for measurement of biological information related to the oxygen circulation time from a plurality of measurement results of a value representing the oxygen concentration.

It is a schematic diagram which shows the example of a measurement of the oxygen saturation in blood. It is a graph which shows the example of a change of the light absorption amount of the light absorbed by the biological body. It is a figure which shows an example of the light absorption amount with respect to each wavelength of an oxygenated hemoglobin and a reduced hemoglobin. It is a figure showing an example of composition of a living body information measuring device concerning a 1st embodiment. It is a figure which shows the example of arrangement | positioning of a light emitting element and a light receiving element. It is a figure which shows the other example of arrangement | positioning of a light emitting element and a light receiving element. It is a figure which shows an example of a respiration waveform. It is a figure which shows the example of a change of the oxygen saturation in the blood accompanying the stop and restart of respiration. It is a figure which shows the example of a change of the reciprocal number of the oxygen saturation in the blood accompanying the stop and restart of respiration. It is a figure which shows an example of the waveform of the measured oxygen saturation. It is a figure which shows an example of the waveform of the oxygen saturation containing several inflection points. It is a figure which shows an example of the waveform of the oxygen saturation characterized by the fluctuation | variation of a value. It is a figure which shows an example of the waveform of oxygen saturation which has the characteristic in the inclination of a waveform. It is a figure which shows the principal part structural example of the electric system in a biological information measuring device. It is a flowchart which shows an example of the flow of the biometric information measurement process which concerns on 1st Embodiment. It is a flowchart which shows an example of the flow of the biometric information measurement process which concerns on 2nd Embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. In addition, the same code | symbol is provided to the component and process which have the same function through all the drawings, and the overlapping description is abbreviate | omitted.

<First Embodiment>
The biological information measuring device 10 is a device that measures biological information related to the circulatory system among information related to the biological body 8 (biological information). The circulatory system is a general term for a group of organs for transporting a body fluid such as blood while circulating in the body.

  Although there are a plurality of values in the biological information related to the circulatory system, as one of the values indicating the state of the heart that sends blood to the blood vessels, for example, the cardiac output (CO: Cardiac Output).

  There are various types of cardiac output, such as suspected left heart failure when the cardiac output falls below the reference value, and suspected right heart failure when the cardiac output increases above the reference value. It is used for examination of heart disease or confirmation of medication effect.

  As a method for measuring cardiac output, for example, a catheter with a balloon at the tip is inserted into the pulmonary artery of a subject who is a measurement target of cardiac output, and oxygen in the blood is expanded and contracted. A method is used in which the saturation is measured and the cardiac output is calculated from the measured oxygen saturation. The oxygen saturation in the blood is an example of a value indicating the oxygen concentration in the blood, a value indicating how much hemoglobin in the blood is bound to oxygen, and the oxygen saturation in the blood is It shows that symptoms such as anemia are likely to occur as the level decreases.

  However, the measurement method of cardiac output using a catheter requires a surgical procedure because it is necessary to insert the catheter into the blood vessel of the measurement subject, and is less invasive in the measurement subject than other measurement methods. Get higher.

  Therefore, there is a method for measuring cardiac output using oxygen saturation obtained from the pulse wave of the subject so that the burden on the subject is less than that of measuring the cardiac output using a catheter. It has been studied. The pulse wave is an attribute that indicates a change in the pulsation of the blood vessel accompanying the delivery of blood by the heart.

  First, a method for measuring the oxygen saturation level in blood will be described with reference to FIG.

  As shown in FIG. 1, the oxygen saturation level in the blood is stretched in the body of the subject that is irradiated with light from the light emitting element 1 toward the body (living body 8) of the subject and received by the light receiving element 3. It is measured using the intensity of light reflected or transmitted by the circulating artery 4, vein 5, capillary 6 or the like, that is, the amount of reflected or transmitted light received.

  FIG. 2 is a conceptual diagram showing the amount of change in the amount of light absorbed by the living body 8, for example. As shown in FIG. 2, the light absorption amount in the living body 8 tends to vary with time.

  Further, looking at the breakdown of the fluctuation of the light absorption amount in the living body 8, the light absorption amount mainly fluctuates by the artery 4, and the light absorption amount does not fluctuate compared to the artery 4 in other tissues including the vein 5 and the stationary tissue. It is known that the amount of change can be regarded as. This is because arterial blood pumped out of the heart moves in the blood vessel with a pulse wave, so that the artery 4 expands and contracts with time along the cross-sectional direction of the artery 4 and the thickness of the artery 4 changes. . In FIG. 2, the range indicated by the arrow 94 indicates the amount of change in the amount of absorption corresponding to the change in the thickness of the artery 4.

In FIG. 2, assuming that the amount of light received at time t _a is I _a and the amount of light received at time t _b is I _b , the amount of change ΔA in the amount of light absorption due to the change in the thickness of the artery 4 can be _expressed by equation (1). Is done.

(Equation 1)
ΔA = ln (I _b / I _a ) (1)

  On the other hand, FIG. 3 is a diagram showing an example of the light absorption amount for each wavelength of hemoglobin (oxygenated hemoglobin) combined with oxygen flowing through the artery 4 and hemoglobin not combined with oxygen (reduced hemoglobin). In FIG. 3, a graph 96 represents the light absorption amount of oxyhemoglobin, and a graph 97 represents the light absorption amount of reduced hemoglobin.

  As shown in FIG. 3, oxyhemoglobin is easier to absorb light in the infrared (IR) region 99 having a wavelength around 850 nm than reduced hemoglobin. It is known that light of the red region 98 having a wavelength around about 660 nm is easily absorbed.

  Furthermore, it is known that the oxygen saturation is proportional to the ratio of the amount of change ΔA in the amount of absorption at different wavelengths.

Therefore, compared to other combinations of wavelengths, the absorption when IR light is irradiated onto the living body 8 using infrared light (IR light) and red light, in which the difference in the amount of light absorption between oxidized hemoglobin and reduced hemoglobin tends to appear. By calculating the ratio between the change amount ΔA _IR of the amount and the change amount ΔA _Red of the light absorption amount when the living body 8 is irradiated with red light, the oxygen saturation S is calculated by the equation (2). In (2), k is a proportionality constant.

(Equation 2)
S = k (ΔA _Red / ΔA _IR ) (2)

  That is, when the oxygen saturation level in the blood is calculated, the living body 8 is irradiated with a plurality of light emitting elements 1 that irradiate light of different wavelengths. Specifically, the light emitting element 1 that emits IR light and the light emitting element 1 that emits red light are used for the living body 8. In this case, the light emission periods of the light emitting element 1 that irradiates IR light and the light emitting element 1 that emits red light may overlap, but preferably the light emission is performed so that the light emission periods do not overlap. Then, the reflected light or transmitted light from each light emitting element 1 is received by the light receiving element 3 and is obtained by modifying the expressions (1) and (2) or these expressions from the amount of light received at each light reception time point. The oxygen saturation is measured by calculating a known formula.

  As a well-known equation obtained by modifying the above equation (1), for example, the equation (1) may be developed and the amount of change ΔA in the amount of light absorption may be expressed as in equation (3).

(Equation 3)
ΔA = lnI _b −lnI _a (3)

  Further, the expression (1) can be modified as the expression (4).

(Equation 4)
ΔA = ln (I _b / I _a ) = ln (1+ (I _b −I _a ) / I _a ) (4)

Usually, because it is _{(I b -I a) «I a} , ln order to _{(I b / I a) ≒} (I b -I a) / I a is satisfied, instead of equation (1), light Equation (5) may be used as the amount of change ΔA in the amount of light absorption.

(Equation 5)
ΔA≈ (I _b −I _a ) / I _a (5)

  Hereinafter, when it is necessary to distinguish between the light-emitting element 1 that emits IR light and the light-emitting element 1 that emits red light, the light-emitting element 1 that emits IR light is referred to as “light-emitting element 1A”. The light-emitting element 1 that irradiates is referred to as “light-emitting element 1B”.

  According to such a method, since the oxygen saturation level in the blood is measured by bringing the light-emitting element 1 and the light-receiving element 3 close to the body surface of the person to be measured, the catheter is inserted into the blood vessel to increase the oxygen saturation level in the blood. The burden on the person to be measured is less than the measurement.

  And the biometric information measuring apparatus 10 calculates cardiac output by the method mentioned later using the measured patient's oxygen saturation.

  FIG. 4 is a diagram illustrating a configuration example of the biological information measuring apparatus 10. As shown in FIG. 4, the biological information measuring apparatus 10 includes a photoelectric sensor 11, a pulse wave processing unit 12, a respiratory waveform extraction unit 13, an oxygen saturation measurement unit 14, a timer 15, a notification unit 16, an oxygen circulation time measurement unit 17, And a cardiac output measuring unit 18.

  The photoelectric sensor 11 receives a light emitting element 1A that emits IR light having a center wavelength of about 850 nm, a light emitting element 1B that emits red light having a center wavelength of about 660 nm, and IR light and red light. A light receiving element 3 is provided.

  FIG. 5 shows an arrangement example of the light emitting element 1 </ b> A, the light emitting element 1 </ b> B, and the light receiving element 3 in the photoelectric sensor 11. As shown in FIG. 5, the light emitting element 1 </ b> A, the light emitting element 1 </ b> B, and the light receiving element 3 are arranged side by side toward one surface of the living body 8. In this case, the light receiving element 3 receives IR light and red light reflected by the capillaries 6 and the like of the living body 8.

  However, the arrangement of the light emitting element 1A, the light emitting element 1B, and the light receiving element 3 is not limited to the arrangement example of FIG. For example, as shown in FIG. 6, the light emitting element 1 </ b> A, the light emitting element 1 </ b> B, and the light receiving element 3 may be arranged at positions facing each other with the living body 8 interposed therebetween. In this case, the light receiving element 3 receives IR light and red light transmitted through the living body 8.

  Here, as an example, the light-emitting element 1A and the light-emitting element 1B are described as surface-emitting laser elements such as VCSEL (Vertical Cavity Surface Emitting Laser), but are not limited thereto, and may be edge-emitting laser elements. Further, the light emitting element 1A and the light emitting element 1B may be LEDs (Light Emitting Diodes).

  The photoelectric sensor 11 is provided with a clip (not shown) for attaching the photoelectric sensor 11 to the body part of the person to be measured. The photoelectric sensor 11 prevents IR light and red light from leaking out of the photoelectric sensor 11. Is attached so as to come into contact with the body surface of the subject by a clip (not shown). In order to receive the IR light and the red light reflected or transmitted by the measurement subject's living body 8 with the light receiving element 3 as accurately as possible, the photoelectric sensor 11 is preferably disposed so as to be in contact with the body surface of the measurement subject. However, within the range in which the IR light and the red light reflected by the measurement subject's living body 8 or the IR light and the red light transmitted through the measurement subject's living body 8 are received by the light receiving element 3, the photoelectric sensor 11 is placed on the body surface. You may attach in the position away from.

  The photoelectric sensor 11 converts the received light amounts of IR light and red light received by the light receiving element 3 into, for example, voltage values and notifies the pulse wave processing unit 12 of them.

  Since a predetermined amount of light is emitted from the light emitting element 1A and the light emitting element 1B, the amount of absorption of IR light and red light in the living body 8 is determined from the amount of received light of IR light and red light received by the photoelectric sensor 11. can get.

  Therefore, the pulse wave processing unit 12 uses the received light amounts of the IR light and the red light received from the photoelectric sensor 11, and the pulse wave signal representing the pulse wave of the measurement subject obtained from the IR light, and the infrared light A pulse wave signal representing the pulse wave of the measurement subject obtained from the light is generated. The pulse wave processing unit 12 amplifies the voltage value so that the voltage values corresponding to the received amounts of received IR light and red light are included in a predetermined range suitable for generating a pulse wave signal. Then, the pulse wave processing unit 12 generates each pulse wave signal from which noise components have been removed using a known filter or the like.

  The pulse wave processing unit 12 notifies each of the generated pulse wave signals to the respiratory waveform extraction unit 13 and the oxygen saturation measurement unit 14.

  When receiving the pulse wave signal from the pulse wave processing unit 12, the respiration waveform extracting unit 13 extracts a respiration waveform representing the breathing state of the measurement subject from the pulse wave signal.

  Specifically, the respiratory waveform extraction unit 13 determines a predetermined period (for example, 1 minute) of either one of the pulse wave signal obtained from IR light and the pulse wave signal obtained from red light. ) And the line connecting the detected local maximum values (peak line) or the line connecting the detected local minimum values (bottom line) is extracted as the respiratory waveform of the person being measured. .

  FIG. 7 is a diagram illustrating an example of a respiratory waveform extracted from the pulse wave signal by the respiratory waveform extraction unit 13.

  Note that the respiratory waveform extraction unit 13 extracts a respiratory waveform using a pulse wave signal obtained from IR light. As shown in FIG. 3, since IR light is more easily absorbed by oxyhemoglobin than red light, the amplitude of the pulse wave signal with respect to the change in the thickness of the artery 4 is that of the pulse wave signal obtained from the red light. There is a tendency to become larger than the amplitude. Therefore, the respiratory waveform extracted from the pulse wave signal obtained from the IR light has a clearer waveform variation than the respiratory waveform extracted from the pulse wave signal obtained from the red light, and a highly accurate respiratory waveform is obtained. Because.

  The respiration waveform extraction unit 13 refers to the respiration waveform extracted from the pulse wave signal, and notifies the notification unit 16 of the respiration state of the measurement subject such as, for example, stop of respiration and resumption of respiration.

  In addition, since the pulse wave signal in a to-be-measured person is obtained by the amount of received light detected by the photoelectric sensor 11, and the respiratory state of the to-be-measured person is detected from the pulse wave signal, the biological information measuring device 10 including the photoelectric sensor 11 is detected. Can be said to be an example of detection means for detecting the presence or absence of breathing of the measurement subject.

When the oxygen saturation measuring unit 14 receives the pulse wave signal from the pulse wave processing unit 12, the oxygen saturation measuring unit 14 measures the oxygen saturation of the measurement subject from the received pulse wave signal. Specifically, the oxygen saturation measuring unit 14 uses the pulse wave signal to calculate the amount of change ΔA _{IR in} the IR light amount due to the change in the thickness of the artery 4 and the amount of change ΔA _{Red in} the light amount of red light. Each is calculated according to equation (1). Then, the oxygen saturation measurement unit 14 uses the calculated change amount ΔA _IR and change amount ΔA _Red to measure the oxygen saturation of the measurement subject, for example, from the equation (2), and the measured oxygen saturation is used as the oxygen circulation. The time measurement unit 17 is notified. As described above, the oxygen saturation measuring unit 14 is an example of a measuring unit that measures a value representing the oxygen concentration in the blood of the measurement subject.

Hereinafter, an example in which the oxygen saturation measuring unit 14 measures the oxygen saturation of the measurement subject will be described as an example. However, the oxygen saturation measurement unit 14 may be a value representing the oxygen concentration in the blood of the measurement subject. Any value may be measured. For example, the oxygen saturation measuring unit 14 may measure a value having a correlation with the temporal change of the oxygen saturation, such as the reciprocal of the oxygen saturation, or the ratio between the change amount ΔA _Red and the change amount ΔA _IR .

  When the breathing waveform extraction unit 13 notifies the subject to stop breathing, the notifying unit 16 starts the timer 15 and when the breathing stop period reaches a predetermined time, Notify the measurer of the resume notice telling him to resume breathing.

  The graph of FIG. 8 shows an example of changes in blood oxygen saturation at a specific site of the subject, with the horizontal axis representing time and the vertical axis representing oxygen saturation.

When the subject stops breathing at time t ₀ , the blood oxygen saturation in the subject begins to decrease. Even if the subject resumes breathing after the elapse of a predetermined time (time t ₁ ) as a period during which the subject stops breathing, the oxygen taken into the blood by resuming breathing is specified from the lungs Since it takes time to reach this region, the blood oxygen saturation level in the measurement subject decreases even after time t ₁ . Among them, since oxygen taken into the blood by resuming breathing reaches a specific site from the lungs, the oxygen saturation level in the blood of the measurement subject starts to increase.

  Hereinafter, the part where the oxygen saturation level in the blood starts to decrease and the part where the blood oxygen saturation starts to increase is called the “inflection point”. The location where the oxygen saturation level in blood changes from decrease to increase, and the location where the oxygen saturation level starts from increase to decrease may not be represented by one point on the oxygen saturation waveform but may have a range.

After breathing resumption of the subject, if the time at which the inflection point appears to oxygen saturation turns from decrease to increase as the time t _2, the oxygen circulation time is expressed by the difference of the time t ₁ and time t _2.

  That is, the oxygen circulation time represents the time required for oxygen to be transported from the lung to a specific site, and is also referred to as “oxygen transport time”.

When the oxygen saturation measuring unit 14 measures the reciprocal of the oxygen saturation, the waveform of the oxygen saturation in the blood at a specific part of the measurement subject is as shown in FIG. 9 and the waveform shown in FIG. Will be upside down. Also in this case, the oxygen circulation time is represented by the difference between time t ₁ and time t ₂ .

  As described above, the waveform of oxygen saturation and the waveform of the reciprocal of oxygen saturation are examples of waveforms representing changes in the value representing the oxygen concentration in the blood of the measurement subject.

  Since the measurement accuracy of the oxygen circulation time measured from the oxygen saturation tends to vary depending on the variation of the breathing stop period, a specified time that defines the breathing stop period is provided.

  The specified time is obtained in advance by an experiment using an actual apparatus of the biological information measuring apparatus 10 or a computer simulation based on the design specifications of the biological information measuring apparatus 10 so that the measurement accuracy of the oxygen circulation time in the biological information measuring apparatus 10 is increased. It is a value.

  Therefore, the notification unit 16 notifies the measurement subject of the resumption of breathing so that the breathing stop period of the measurement subject approaches the specified time, and the oxygen circulation time measurement unit 17 also resumes the breathing of the measurement subject. Notify you.

When the oxygen circulation time measurement unit 17 receives from the notification unit 16 that the measurement subject's respiration has been resumed, the oxygen circulation time measurement unit 17 stores the time at which resumption of respiration was accepted as time t ₁ . Then, the oxygen circulation time measurement unit 17 monitors the change in the oxygen saturation measured by the oxygen saturation measurement unit 14 and detects the inflection point of the oxygen saturation. Table oxygen circulation time measuring unit 17 stores the time at which the oxygen saturation after resuming breathing of the subject detects the inflection points starts increasing decrease as the time t _2, the time t ₁ and time t ₂ the difference Is measured as the oxygen circulation time.

  Then, the oxygen circulation time measurement unit 17 notifies the cardiac output measurement unit 18 of the measured oxygen circulation time.

  The waveform of oxygen saturation shown in FIG. 8 is an inflection point where the measurement starts monotonously decreasing after the subject stops breathing, and after the subject resumes breathing, the oxygen saturation turns from decreasing to increasing. Shows an example of an ideal oxygen saturation waveform showing a change that approaches one before the oxygen saturation before stopping breathing.

  However, as shown in FIG. 10, the actually measured oxygen saturation waveform may be different from the ideal oxygen saturation waveform, for example, a plurality of inflection points appear. This is presumably because an error factor that reduces the measurement accuracy of the oxygen saturation acts on the measurement of the oxygen saturation of the measurement subject.

  The error factors of oxygen saturation include, for example, changes in the measurement environment such as the contact state of the photoelectric sensor 11 that contacts the subject's body surface, and psychological and physical changes of the subject such as the tension of the subject. Is included. Furthermore, the error factor of oxygen saturation includes disturbance such as measurement error of the photoelectric sensor 11 due to the influence of sunlight, for example, and the breathing is resumed while the measured person reaches the specified time, and the breathing is stopped again. Such changes in stability with respect to respiratory conditions are included.

  When an ideal oxygen saturation waveform as shown in FIG. 8 is obtained, an error factor in measuring the oxygen saturation is suppressed as compared with the case where other waveforms are obtained. Means that.

  In other words, as the deviation of the oxygen saturation waveform measured by the oxygen saturation measuring unit 14 from the ideal waveform shape shown in FIG. 8 increases, the reliability of the measured oxygen saturation decreases. It is estimated to go. The decrease in the reliability of the measured oxygen saturation also decreases the reliability of the measurement result in the oxygen circulation time measurement unit 17, and further the living body related to the oxygen circulation time measured in the cardiac output measurement unit 18. It also reduces the reliability of information. That is, the measurement accuracy of biological information related to the oxygen circulation time is lowered.

  Therefore, the oxygen circulation time measurement unit 17 refers to a condition (conformity condition) that is predetermined as a waveform condition of oxygen saturation suitable for measurement of biological information related to oxygen circulation time, and refers to a living body related to oxygen circulation time. Calculate the reliability of the oxygen saturation waveform used to measure the information. The reliability is an example of an index that represents the degree to which the waveform of oxygen saturation is suitable or not suitable for measurement of biological information related to oxygen circulation time. In other words, the reliability of the waveform representing the change in oxygen saturation is an example of an index representing the degree of conformity or nonconformity of oxygen saturation with respect to the measurement of biological information related to oxygen circulation time, and the measurement accuracy of biological information Represents.

  Then, the oxygen circulation time measurement unit 17 notifies the notification unit 16 of the calculated index. The biological information related to the oxygen circulation time may be simply expressed as “biological information”.

  The adaptation condition includes a change tendency of oxygen saturation suitable for measurement of biological information, that is, a condition relating to a waveform of oxygen saturation.

  A waveform of oxygen saturation suitable for measurement of biological information is defined by, for example, the number of inflection points included in the waveform.

FIG. 11 is a diagram illustrating an example of a waveform of oxygen saturation measured by the oxygen saturation measuring unit 14. The oxygen saturation waveform shown in FIG. 11 includes seven inflection points H _{1 to} H _{7. As} shown in FIG. 8, the ideal oxygen saturation waveform includes, for example, breathing. The inflection point that appears when the oxygen saturation decreased by the cessation of the gas starts to increase by the resumption of breathing is included. In addition, the ideal oxygen saturation waveform includes, for example, a case where the oxygen saturation starts to decrease from the value before stopping breathing due to the stoppage of breathing, or a decrease in oxygen saturation is caused by resuming breathing. An inflection point may also appear when recovering to the value before stopping.

  Thus, the ideal oxygen saturation waveform may include a plurality of inflection points, but there is an upper limit to the number of inflection points, and as the number of inflection points increases, There is a tendency for the shape of the oxygen saturation waveform to deviate from the ideal oxygen saturation waveform.

Therefore, a suitable condition in which the upper limit value of the inflection point is set to N ₁ (N ₁ is a positive integer) is prepared in advance, and the oxygen circulation time measurement unit 17 determines the oxygen measured by the oxygen saturation measurement unit 14. When the number of inflection points included in the saturation waveform is equal to or less than the upper limit value of the inflection point set in the conforming condition, the oxygen saturation waveform measured by the oxygen saturation measuring unit 14 is biometric information. It is determined that the waveform is suitable for measurement.

  The method of setting the number of inflection points in the adaptation conditions is not limited to this, for example, the upper limit of the inflection point at which the oxygen saturation turns from decrease to increase, and the upper limit of the inflection point at which the oxygen saturation turns from increase to decrease. Each value may be set.

Further, since the ideal oxygen saturation waveform includes at least one inflection point, in addition to the upper limit value N ₁ of the inflection point, a lower limit value N ₂ (N ₂ is a positive integer) is set. It may be set. In this case, the range of the number of inflection points in the oxygen saturation suitable for measurement of biological information is set as the matching condition.

  Furthermore, the oxygen saturation waveform suitable for the measurement of biological information is defined by the magnitude of the oxygen saturation value at the inflection point, for example.

  FIG. 12 is a diagram illustrating an example of a waveform of oxygen saturation measured by the oxygen saturation measuring unit 14. When measuring the oxygen saturation, for example, when a disturbance such as sunlight entering the light receiving element 3 of the photoelectric sensor 11 occurs, this becomes noise and affects the measured value of oxygen saturation. FIG. As described above, the magnitude of the difference between values at adjacent inflection points may increase to a value that cannot be found in an ideal oxygen saturation waveform. In addition, the measurement of oxygen saturation cannot be performed normally due to a failure of the photoelectric sensor 11 or the like, and the magnitude of the difference in values at adjacent inflection points is the ideal oxygen saturation as shown in FIG. It may be reduced to a value that cannot be seen in the waveform.

  That is, the magnitude of the value at the inflection point of the waveform representing oxygen saturation is the value of the oxygen saturation at the inflection point of interest and the inflection immediately before the inflection point adjacent to the inflection point in time series. It means the magnitude of the difference from the value of oxygen saturation at a point.

  Thus, there are an upper limit value and a lower limit value for the magnitude of the value of the inflection point in the ideal oxygen saturation waveform. In the case of a waveform having an inflection point whose magnitude of the measured oxygen saturation value is not included in the range represented by the upper limit value and the lower limit value, the shape of the oxygen saturation waveform is an ideal oxygen saturation level. There is a tendency to deviate from the waveform.

Therefore, a suitable condition in which the upper limit value of the oxygen saturation value at the inflection point is set to M ₁ and the lower limit value is set to M ₂ (M ₁ and M ₂ are both positive numbers) is prepared in advance. The circulation time measuring unit 17 was measured by the oxygen saturation measuring unit 14 when the magnitude of the inflection point in the oxygen saturation measured by the oxygen saturation measuring unit 14 was M ₂ or more and M ₁ or less. It is determined that the waveform of oxygen saturation is a waveform suitable for measurement of biological information.

  As an example, the magnitude of the value at the inflection point of the waveform representing the oxygen saturation is adjacent to the value of the oxygen saturation at the inflection point of interest and the inflection point in time series. Although it is defined by the difference from the value of the oxygen saturation at the inflection point immediately before, it may be defined by the difference from the value of the oxygen saturation at the inflection point immediately adjacent along the time series.

  Moreover, the oxygen saturation waveform suitable for the measurement of biological information is defined by, for example, the magnitude of the waveform slope between the inflection points adjacent in time series.

  FIG. 13 is a diagram illustrating an example of a waveform of oxygen saturation measured by the oxygen saturation measuring unit 14. When measuring the oxygen saturation, if the error factor of the oxygen saturation acts, the magnitude of the waveform slope between adjacent inflection points is, for example, as shown in FIG. The value may increase to a value that cannot be seen in the waveform, or may decrease to a value that cannot be found in the ideal oxygen saturation waveform, as shown in FIG.

  Thus, there are an upper limit value and a lower limit value for the magnitude of the waveform slope between the inflection points of the ideal oxygen saturation waveform. In the case of an oxygen saturation waveform where the magnitude of the slope of the waveform between the inflection points is not included in the range represented by the upper limit value and the lower limit value, the shape of the oxygen saturation waveform has an ideal oxygen saturation level. There is a tendency to deviate from the waveform.

Therefore, a suitable condition in which the upper limit value of the slope of the waveform between the inflection points is set to L ₁ and the lower limit value is set to L ₂ (L ₁ and L ₂ are both positive numbers) is prepared in advance, and oxygen circulation The time measuring unit 17 is configured to detect oxygen when the magnitude of the waveform slope between inflection points adjacent to each other along the time series of oxygen saturation measured by the oxygen saturation measuring unit 14 is L ₂ or more and L ₁ or less. It is determined that the waveform of oxygen saturation measured by the saturation measuring unit 14 is a waveform suitable for measurement of biological information.

The upper limit value N ₁ and the lower limit value N _{2 of} the inflection point set in the conforming condition, the upper limit value M ₁ and the lower limit value M ₂ of the magnitude of the oxygen saturation at the inflection point, and the inflection point The upper limit value L ₁ and the lower limit value L ₂ of the magnitude of the waveform inclination between the values are values obtained in advance by, for example, experiments with the actual apparatus of the biological information measuring apparatus 10 or computer simulation based on the design specifications of the biological information measuring apparatus 10. is there.

  The notification unit 16 that has received the index from the oxygen circulation time measurement unit 17 uses the received index as, for example, a person to be measured, a measurer such as a medical worker who measures biological information of the person to be measured, and the biological information measuring apparatus 10. To at least one related person (hereinafter referred to as “user of the biological information measuring apparatus 10”).

  That is, the biological information measuring device 10 notifies the user of the biological information measuring device 10 of an index indicating the measurement accuracy of biological information measured using the oxygen circulation time obtained from the waveform of the oxygen saturation of the measurement subject. To do.

  In addition, although the measurement site | part of oxygen circulation time is determined by the attachment position of the photoelectric sensor 11 in a to-be-measured person, in this Embodiment, the photoelectric sensor 11 is mounted | worn with a to-be-measured person's fingertip, oxygen is supplied from a lung to a fingertip. Measure oxygen circulation time when transported. This is because the oxygen circulation time becomes longer due to the longer distance from the lungs compared to other parts, so the oxygen circulation time is more accurate than when the photoelectric sensor 11 is attached to other parts. It is because it is obtained.

  Therefore, the oxygen circulation time from the lung to the fingertip is sometimes referred to as LFCT (Lung to Finger Circulation Time). Also in the present embodiment, an example in which the photoelectric sensor 11 is attached to the fingertip of the measurement subject and the LFCT is measured by the oxygen circulation time measurement unit 17 will be described, but the attachment site of the photoelectric sensor 11 is not limited to the fingertip. The photoelectric sensor 11 may be attached to any part of the measurement subject as long as the obtained measurement error of the oxygen circulation time is within a predetermined range. For example, a part (erasure part) on the side closer to the measurement subject's neck, shoulder, and hip joint is an example of the attachment part. The “fingertip” refers to the fingertip of the measurement subject's hand, but the photoelectric sensor 11 may be attached to the fingertip of the foot.

  The cardiac output measuring unit 18 is an example of an information measuring unit that measures the cardiac output of the subject using the LFCT received from the oxygen circulation time measuring unit 17.

  The cardiac output CO is obtained from LFCT using a known arithmetic expression shown in, for example, the expression (6).

(Equation 6)
CO = (a0 × S) / LFCT (6)

Here, a0 is a constant, and for example, a0 = 50 is used. S is the body surface area (m ² ) of the measurement subject, and the unit of LFCT is second.

  The cardiac output measuring unit 18 may measure information related to cardiac output in addition to cardiac output. “Information related to cardiac output” is information that is correlated with cardiac output, and includes, for example, a cardiac coefficient and stroke volume.

  The “cardiac coefficient” is a value obtained by dividing the cardiac output of the measured person by the body surface area of the measured person in order to correct the difference in cardiac output due to the difference in the physique of the measured person. The “stroke volume” is a value indicating the volume of blood that the heart pumps into the artery 4 by one contraction, and the cardiac output is divided by the one-minute heart rate of the person to be measured. Is required.

  The cardiac output, cardiac coefficient, and stroke volume obtained from the oxygen circulation time measured by the oxygen circulation time measurement unit 17 are the values of the biological information related to the oxygen circulation time measured by the biological information measuring device 10. It is an example.

  The biological information measuring device 10 described above is configured using, for example, a computer. FIG. 14 is a diagram illustrating a configuration example of a main part of the electrical system in the biological information measuring apparatus 10 configured using the computer 20.

  The computer 20 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, which function as measurement means, notification means, reception means, and information measurement means according to the present embodiment. A nonvolatile memory 24 and an input / output interface (I / O) 25 are provided. The CPU 21, ROM 22, RAM 23, nonvolatile memory 24, and I / O 25 are connected via a bus 26. There is no limitation on the operation system used in the computer 20.

  The non-volatile memory 24 is an example of a storage device that maintains stored information even when power supplied to the non-volatile memory 24 is cut off. For example, a semiconductor memory is used, but it may be a hard disk.

  For example, the photoelectric sensor 11, the input unit 27, the display unit 28, and the communication unit 29 are connected to the I / O 25.

  The photoelectric sensor 11 is connected to the I / O 25 by wire or wireless. The biological information measuring device 10 and the photoelectric sensor 11 may be separated from each other so that the biological information measuring device 10 and the photoelectric sensor 11 are integrated. It is good also as a structure accommodated in the same housing.

  The input unit 27 is a unit that receives an instruction from the user of the biological information measuring apparatus 10 and notifies the CPU 21 of the instruction, for example. The input unit 27 includes, for example, a button, a touch panel, a keyboard, a mouse, and the like.

  The display unit 28 is a unit that visually displays, for example, information processed by the CPU 21 to the user of the biological information measuring device 10. For the display unit 28, for example, a display device such as a liquid crystal display, an organic EL (Electro Luminescence), and a projector is used.

  The display unit 28 is not necessarily a unit necessary for the biological information measuring device 10. For example, any type of unit may be used as long as it notifies the user of the biological information measuring device 10 of information notified from the biological information measuring device 10 such as a resumption notification of breathing or an index indicating the measurement accuracy of the biological information. It may be connected to the I / O 25.

  For example, when the information notified from the biological information measuring device 10 is notified to the user of the biological information measuring device 10 by voice, for example, a speaker unit may be connected instead of the display unit 28. Further, when notifying the user of the biological information measuring device 10 of the information notified from the biological information measuring device 10 through the bodily sensation, for example, a vibration unit may be connected instead of the display unit 28. Furthermore, the information notified from the biological information measuring device 10 may be notified to the user of the biological information measuring device 10 using a plurality of units such as the display unit 28 and the speaker unit.

  Hereinafter, an example of notifying the user of the biological information measuring device 10 by displaying information notified from the biological information measuring device 10 on the display unit 28 will be described. However, at least one of display, sound, and bodily sensation is described. You may alert | report using.

  The communication unit 29 includes a communication protocol for connecting the biological information measuring device 10 with a communication line such as the Internet, for example, and performs data communication between another external device connected to the communication line and the biological information measuring device 10. The connection form to the communication line in the communication unit 29 may be wired or wireless. If the biological information measuring device 10 does not need to perform data communication with other external devices connected to the communication line, it is not always necessary to connect the communication unit 29 to the I / O 25.

  The unit connected to the I / O 25 is not limited to the example described above, and other units such as a printing unit may be connected to the I / O 25, for example.

  Next, the operation of the biological information measuring apparatus 10 will be described with reference to FIG.

  As an example, when the biological information measuring device 10 receives an instruction to measure cardiac output from the user of the biological information measuring device 10 via the input unit 27, the biological information measuring device 10 is covered by the photoelectric sensor 11 attached to the fingertip of the measured person. The measurement of the oxygen saturation of the measurer is started, and the value of the oxygen saturation measured over the cardiac output measurement period is stored in the nonvolatile memory 24 in time series.

  Here, the `` measurement period '' is a period set longer than the specified time set as the breathing stop period and the longest LFCT that can be assumed medically, and the measurement of cardiac output This is the period from when an instruction is received until the oxygen saturation level at which LFCT can be measured is obtained. Further, the storage destination of the value of the oxygen saturation is an example, and may be stored in the RAM 23 or in a storage unit of an external device connected to the communication line.

  Thereafter, the biological information measuring device 10 acquires the stored value of oxygen saturation and starts the biological information measuring process.

  FIG. 15 is a flowchart illustrating an example of the flow of the biological information measurement process executed by the CPU 21.

  A biological information measurement program that defines the biological information measurement process is stored in advance in the ROM 22 of the biological information measurement device 10, for example. The CPU 21 of the biological information measuring device 10 reads a biological information measuring program stored in the ROM 22 and executes a biological information measuring process.

  The conforming conditions are stored in advance in, for example, the nonvolatile memory 24. However, the storage destination of the conforming conditions is not limited to the nonvolatile memory 24, and is a storage unit of an external device connected to the communication line. Also good. In this case, the CPU 21 acquires the matching condition from the external device via the communication unit 29.

  First, in step S <b> 10, the CPU 21 initializes a reliability D representing the measurement accuracy of biological information measured by the biological information measuring device 10 to “0”. The reliability D indicates that “0” has the highest measurement accuracy of biological information (that is, the waveform of oxygen saturation is suitable for measurement of biological information), and is measured as the value of the reliability D increases. It shows that the measurement accuracy of the biometric information is low.

  In step S20, the CPU 21 analyzes the acquired oxygen saturation value along a time series, and detects all inflection points from the waveform represented by the change in the oxygen saturation value.

In step S30, the CPU 21 determines whether or not the number of inflection points included in the waveform is not less than the lower limit value N _{2 and not} more than the upper limit value N _{1 of the} inflection points set in the matching conditions. When the number of inflection points included in the waveform is less than the lower limit value N ₂ or exceeds the upper limit value N ₁ , the process proceeds to step S40.

In this case, the measurement accuracy of the biological information obtained is lower than that of the waveform having the number of inflection points equal to or higher than the lower limit value N ₂ and lower than the upper limit value N _1. D ₁ (D ₁ is a positive number) is added to the degree D. D ₁ is a value corresponding to the degree of non-conformity when a waveform whose number of inflection points does not satisfy the conforming condition is used for measurement of biological information.

On the other hand, if the number of inflection points included in the waveform is not less than the lower limit value N _{2 and not} more than the upper limit value N ₁ , that is, if the waveform of oxygen saturation satisfies the conformity condition, the process proceeds to step S50.

In step S50, the CPU 21 selects any one inflection point included in the waveform, and the magnitude of the value of oxygen saturation at the selected inflection point, specifically, the value at the selected inflection point. Then, it is determined whether or not the magnitude of the difference between the selected inflection point and the value at the immediately preceding inflection point adjacent in time series is not less than the lower limit value M _{2 and not} more than the upper limit value M ₁ . If the magnitude of the oxygen saturation value at the inflection point is less than the lower limit M ₂ or exceeds the upper limit M ₁ , the process proceeds to step S60.

In this case, the measured waveform is compared with the case where the waveform in which the value of the oxygen saturation at the inflection point is the lower limit M ₂ or more and the upper limit M ₁ or less is used for the measurement of biological information. Therefore, in step S60, the CPU 21 adds D ₂ (D ₂ is a positive number) to the reliability D. D ₂ is an incompatibility of the waveform with respect to the measurement of biological information when the waveform of the oxygen saturation at the inflection point is less than the lower limit value M ₂ or exceeds the upper limit value M ₁ in the measurement of biological information. The value corresponds to the degree.

  Here, as an example, the difference between the value at the selected inflection point and the value at the previous inflection point adjacent to the selected inflection point in time series is the oxygen saturation value at the selected inflection point. The size of However, instead of the determination of the difference or in addition to the determination of the difference, it is determined for each inflection point whether or not the magnitude of the oxygen saturation value itself at the selected inflection point satisfies the conformity condition. May be.

On the other hand, when the magnitude of the oxygen saturation value at the inflection point is not less than the lower limit M _{2 and not} more than the upper limit M ₁ , that is, when the magnitude of the oxygen saturation satisfies the conformity condition. Control goes to step S70.

  In step S <b> 70, the CPU 21 determines whether or not the magnitude of the oxygen saturation value is matched with the matching condition for all the inflection points detected from the oxygen saturation waveform in step S <b> 20.

  If there is an inflection point for which the magnitude of the oxygen saturation value has not yet been compared with the matching condition, that is, an unselected inflection point that has not been selected in step S50, the process proceeds to step S50. Thereafter, Steps S50 to S70 are performed on the unselected inflection points, so that the value of the oxygen saturation value is large for each inflection point detected from the oxygen saturation waveform in Step S20. And a comparison of matching conditions is performed.

In step S80, the CPU 21 selects any one inflection point included in the waveform representing oxygen saturation, and selects the inflection point immediately before the selected inflection point and the selected inflection point in time series. It is determined whether or not the slope of the waveform between the inflection point is the lower limit value L ₂ or more and the upper limit value L ₁ or less. Hereinafter, the magnitude of the slope of the waveform between the selected inflection point and the immediately preceding inflection point adjacent to the selected inflection point in time series is simply expressed as “the waveform corresponding to the selected inflection point. "The magnitude of the slope of".

  In the present embodiment, the magnitude of the slope of the waveform corresponding to the selected inflection point is set to the magnitude of the slope of the waveform at each measurement point of oxygen saturation existing between the immediately preceding inflection point. Of these, the maximum size is used, but various statistics such as a minimum value, an average value, or a center value may be used.

If the magnitude of the waveform slope corresponding to the selected inflection point is less than the lower limit L ₂ or exceeds the upper limit L ₁ , the process proceeds to step S90.

In this case, it is measured in comparison with a case where a waveform whose magnitude of the waveform corresponding to the selected inflection point is not less than the lower limit L _{2 and not} more than the upper limit L ₁ is used for the measurement of biological information. Therefore, in step S90, the CPU 21 adds D ₃ (D ₃ is a positive number) to the reliability D.

D ₃ is a waveform for the measurement of biological information when a waveform whose magnitude of the waveform corresponding to the selected inflection point is less than the lower limit L ₂ or exceeds the upper limit L ₁ is used for the measurement of biological information. This value corresponds to the degree of non-conformity.

On the other hand, when the magnitude of the slope of the waveform corresponding to the selected inflection point is not less than the lower limit value L _{2 and not} more than the upper limit value L ₁ , that is, the magnitude of the slope of the waveform corresponding to the selected inflection point. If the matching condition is satisfied, the process proceeds to step S100.

  In step S100, the CPU 21 determines whether or not the magnitude of the slope of the waveform corresponding to the inflection point is compared with the matching condition for all the inflection points detected from the oxygen saturation waveform in step S20. .

  If there is an inflection point for which the magnitude of the waveform gradient has not been compared with the matching condition, that is, an unselected inflection point that has not been selected in step S80, the process proceeds to step S80. Thereafter, steps S80 to S100 are performed on unselected inflection points, so that the waveform corresponding to the inflection point for each of the inflection points detected from the oxygen saturation waveform in step S20. A comparison is made between the magnitude of the slope and the matching condition.

In step S110, CPU 21 from time t ₁ to the subject resumes breathing after resuming breathing of the subject, the time until time t ₂ when the inflection point the oxygen saturation changes to increase from decrease appears LFCT Measure as

In addition, when there are multiple inflection points where the oxygen saturation changes from decreasing to increasing after the subject's breathing resumes, for example, the inflection points where the magnitude of the oxygen saturation value matches the conforming condition. , the largest inflection point size of the oxygen saturation value time may be regarded as the time t ₂ the appearing. The inflection point that appears when the subject resumes breathing appears because the subject has stopped breathing until then, and the oxygen saturation level is the smallest. Therefore, the magnitude of the value of the inflection point that appears when the measurement subject resumes breathing tends to be larger than the magnitude of the value at other inflection points.

  In step S120, CPU21 measures cardiac output from (6) Formula, for example using LFCT acquired by step S110. Further, the CPU 21 may calculate information related to the cardiac output using the measured cardiac output.

  In step S130, the CPU 21 displays the reliability D on the display unit 28 together with the cardiac output measured in step S120. Thereby, the measurement accuracy of the cardiac output measured in step S120 is notified to the user of the biological information measuring device 10. Although the example in which the reliability D is displayed on the display unit 28 after the measurement of the cardiac output has been described here, the reliability D may be displayed from the beginning of the biological information measurement process (for example, step S10). In this case, the reliability D is updated as the analysis of the oxygen saturation waveform progresses.

  The display form of the reliability D is not limited. In addition to the display form in which the reliability D is directly displayed on the display unit 28 as the measurement accuracy of the cardiac output, the case where the reliability D is “0” is output. Percentage associated with the measurement value of the quantity being 100%, and associated with the reliability value of the cardiac output being 0% when the reliability D is equal to or greater than a predetermined threshold value Alternatively, the value of reliability D may be converted to display the measurement accuracy of cardiac output such as “reliability 90%”.

  Further, the range that the reliability D can take may be divided into a plurality of sections, and the label names associated with the sections including the reliability D may be displayed on the display unit 28. For example, when the range of possible values of the reliability D is divided into three sections, the reliability D in the present embodiment indicates that the smaller the value, the higher the measurement accuracy of the cardiac output. If the label names are associated in the order of “high”, “medium”, and “low” from the category including the small reliability D to the category including the large reliability D, depending on the reliability D The classification name indicating the level of measurement accuracy of the measured biological information is displayed.

  Further, the reliability D is compared with a predetermined determination threshold value. When the reliability D is less than the determination threshold value, for example, “applicable” is displayed so that the measured cardiac output is a reliable value. May be displayed. On the other hand, when the reliability D is equal to or higher than the determination threshold value, for example, “not fit” may be displayed to indicate that the measured cardiac output is not a formal value but a reference value. As described above, the indications of “conformity” and “nonconformity” are also examples of indices indicating the degree of conformity or the degree of incompatibility of the oxygen saturation waveform with respect to the measurement of biological information.

  Furthermore, according to the reliability D, the display name of the label name, the reliability D, and at least one information corresponding to the reliability D may be changed.

  Thus, the biological information measurement process shown in FIG. 15 is finished.

  In the biological information measuring apparatus 10 according to the present embodiment, the measurement accuracy of the biological information is determined using the matching condition that defines the condition of the oxygen saturation waveform suitable for the measurement of the biological information related to the oxygen circulation time. . However, the measurement accuracy of the biological information may be determined using a nonconforming condition that defines a condition of the oxygen saturation waveform that is not suitable for the measurement of the biological information related to the oxygen circulation time.

  When the nonconformity condition is used, the biological information measuring apparatus 10 determines whether or not the attribute value related to the waveform of the oxygen saturation that is the determination target satisfies the nonconformity condition in each determination process of steps S30, S50, and S70. What is necessary is just to judge. In each determination process of steps S30, S50, and S70, when the attribute value does not satisfy the nonconformity condition, steps S50, S70, and S100 are executed, respectively, and when the attribute value satisfies the nonconformance condition , Steps S40, S60, and S90 are executed.

  As described above, according to the biological information measuring apparatus 10 according to the first embodiment, the biometric information measurement is performed by comparing the predetermined conforming condition or nonconforming condition with the attribute value indicating the characteristic of the oxygen saturation waveform. The reliability D of the oxygen saturation used for the calculation is calculated, and the measurement accuracy for the measurement result of the biological information is notified based on the calculated reliability D.

<Variation 1 of the first embodiment>
The biological information measurement process shown in FIG. 15 temporarily stores each value of oxygen saturation measured over the measurement period of cardiac output in a storage device such as the nonvolatile memory 24, and measures the oxygen saturation. After finishing the above, the cardiac output and the reliability D of the measurement subject were notified using the value of the oxygen saturation stored in the storage device. However, each time the inflection point is detected from the waveform of the oxygen saturation by sequentially analyzing the oxygen saturation measured during the measurement period of the cardiac output along the real time, for example, step S30 shown in FIG. , S50 and S80 may be executed, and the value of the reliability D may be updated so that the reliability D is increased when the determination result is negative in each determination process.

In this case, each time an inflection point is detected, the number of inflection points included in the waveform is incremented by one. Therefore, in step S30, the detected inflection point is not determined without determining the lower limit value. the number of inflection point may be determined whether it is not more than the upper limit N _1. Then, for example, when the measurement of the oxygen saturation is finished, it is determined whether or not the total number of detected inflection points is equal to or higher than the lower limit N ₂ , and the reliability D is increased so that the reliability D is increased in the case of negative determination. The value of degree D may be updated.

<Modification 2 of the first embodiment>
In the present embodiment, the reliability D is initialized to 0 in step S10, and it has been shown that the measurement accuracy of the measured biological information decreases as the reliability D increases. However, for example, the reliability D may be initialized to a predetermined positive number in step S10, and D ₁ , D ₂ , and D ₃ may be subtracted from the reliability D in steps S40, S60, and S90, respectively. In this case, as the reliability D becomes smaller, the measurement accuracy of the measured biological information becomes lower.

<Modification 3 of the first embodiment>
In this embodiment, paying attention to the magnitude of the slope of the waveform corresponding to the inflection point, the reliability D of the measured oxygen saturation is calculated, but the degree of variation in the slope of the waveform corresponding to the inflection point is calculated. Accordingly, the reliability D of the measured oxygen saturation may be calculated.

  Here, “the degree of variation in the slope of the waveform corresponding to the inflection point” means the inflection point at each inflection point in the oxygen saturation waveform, and the inflection point and time series in question. This means the degree of variation in the slope of the waveform between the adjacent inflection points immediately before and after.

  Specifically, the biological information measuring apparatus 10 uses the dispersion value of the slope of the waveform at each measurement point of the oxygen saturation existing between the inflection points, or the standard deviation, and the slope of the waveform corresponding to the inflection point. The degree of variation is calculated.

  In an ideal oxygen saturation waveform, the degree of variation in the slope of the waveform corresponding to the inflection point is included in a predetermined range. Therefore, the biological information measuring device 10 measures biological information using an ideal oxygen saturation waveform when the degree of variation in the slope of the waveform corresponding to the inflection point is not included in the predetermined range. The reliability D may be updated so as to indicate that the measurement accuracy of the measured biological information is lower than the case where the measurement is performed. The range of the degree of variation in inclination in the waveform of oxygen saturation suitable for the measurement of biological information may be set in advance as an appropriate condition. On the other hand, the degree of inclination variation in the oxygen saturation waveform, which is not suitable for measurement of biological information, may be set in advance as a nonconforming condition. In any case, the biological information measuring apparatus 10 updates the reliability D based on whether or not the waveform of the oxygen saturation matches the conforming condition or the nonconforming condition.

  The index indicating the degree of variation in the slope of the waveform corresponding to the inflection point is not limited to the variance value or the standard deviation, and any index can be used as long as it represents the degree of variation in the slope of the waveform corresponding to the inflection point. May be used.

<Modification 4 of the first embodiment>
Since the inflection point used for the measurement of LFCT is an inflection point that appears when the subject resumes breathing, the inflection point appears after the subject resumes breathing. In addition, since it takes time for oxygen taken into the blood due to resumption of breathing to reach a specific site from the lung, the inflection point used in the measurement of LFCT is the time t when the subject resumes respiration. Appears after a predetermined time (standby time) has elapsed from ₁ .

  That is, before the lapse of the waiting time, the oxygen saturation waveform such that an inflection point where the oxygen saturation turns from decreasing to increasing appears, or the inflection point does not appear once after the lapse of the waiting time. The oxygen saturation waveform tends to deviate from the ideal oxygen saturation waveform.

  Therefore, when the inflection point where oxygen saturation turns from increase to decrease appears before the lapse of the waiting time, or when the inflection point does not appear once after the lapse of the waiting time, the biological information measuring apparatus 10 For example, the reliability D may be updated so as to indicate that the measurement accuracy of the measured biological information is lower than when the biological information is measured using an ideal oxygen saturation waveform. Information relating to the appearance position of the inflection point in the waveform of oxygen saturation suitable for the measurement of biological information may be set in advance as an appropriate condition. On the other hand, information regarding the appearance position of an inflection point in a waveform of oxygen saturation that is not suitable for measurement of biological information may be set in advance as a nonconforming condition. In any case, the biological information measuring apparatus 10 updates the reliability D based on whether or not the waveform of the oxygen saturation matches the conforming condition or the nonconforming condition.

<Modification 5 of the first embodiment>
In the biological information measuring apparatus 10 according to the present embodiment, the reliability D of the oxygen saturation waveform measured over the cardiac output measurement period is calculated based on one predetermined matching condition.

  However, the shape of the ideal oxygen saturation waveform varies depending on the breathing state of the subject. For example, daily breathing is repeated until the subject stops breathing, so the fluctuation range of oxygen saturation is within a predetermined fluctuation range compared to the breathing stop period, for example. Tend to fit in. In addition, during the period in which the measurement subject has stopped breathing, oxygen is no longer taken into the blood from the lung, and thus there is a tendency for oxygen saturation to decrease. In addition, the oxygen saturation continues to decrease until the oxygen taken into the blood reaches the fingertip from the lungs by resuming breathing, and increases after the oxygen reaches the fingertip. The waveform of the degree tends to be unimodal.

  Therefore, the cardiac output measurement period is divided into, for example, the period before stopping breathing, the period when stopping breathing, and the period after restarting breathing, and the characteristics of the ideal oxygen saturation waveform are defined for each period. You may make it set the adapted condition.

  Then, the biological information measuring apparatus 10 may perform the biological information measuring process shown in FIG. 15 with reference to the matching condition corresponding to the period including the inflection point detected from the oxygen saturation waveform. In this case, the biological information measuring apparatus 10 may notify the calculated reliability D in at least one period of each period. However, in order to notify the measurement accuracy of the measured biological information to the user of the biological information measuring device 10, the biological information measuring device 10 notifies the reliability D at least during the period after the measurement subject resumes breathing. Is preferred.

  The reliability D to be notified may be the reliability D calculated individually for each period or may be the reliability D calculated by accumulating over each period.

Second Embodiment
In the biological information measuring apparatus 10 according to the first embodiment, the degree of conformity or degree of incompatibility of the oxygen saturation waveform with respect to the measurement of cardiac output is reported.

  When the notified degree of conformity is lower than a predetermined reference, that is, when the notified degree of nonconformity is higher than a predetermined reference, the measured cardiac output value is calculated based on the measured patient's cardiac output. It's hard to say it's correct. Therefore, in many cases, the user of the biological information measuring apparatus 10 measures the cardiac output of the measurement subject again.

  However, in the biological information measuring apparatus 10 according to the first embodiment, since the measurement accuracy of the cardiac output measured after measuring the cardiac output is notified, the reliability is lower than a predetermined reference. After waiting for the measurement of cardiac output to be completed, the cardiac output of the measurement subject is measured again.

  In the second embodiment, even if the degree of conformity of the oxygen saturation waveform with respect to the measurement of cardiac output is lower than a predetermined reference, the cardiac output is not waited until the measurement of cardiac output is completed. A biological information measurement apparatus 10A that is ready for remeasurement of the stroke volume will be described.

  The configuration example of the biological information measurement device 10A and the configuration example of the main part of the electrical system are the configuration example of the biological information measurement device 10 according to the first embodiment shown in FIGS. Same as example.

  FIG. 16 shows the measurement of biological information performed by the CPU 21 after measuring the value of oxygen saturation over the measurement period of cardiac output, and storing each measured value of oxygen saturation in the storage device. It is a flowchart which shows an example of the flow of a process.

  A biological information measurement program that defines the biological information measurement process is stored in advance in the ROM 22 of the biological information measurement apparatus 10A, for example. The CPU 21 of the biological information measuring device 10A reads a biological information measuring program stored in the ROM 22 and executes a biological information measuring process.

  Also in the second embodiment, an example will be described in which the matching conditions are stored in advance in the nonvolatile memory 24 and the cardiac output of the measurement subject is measured as a value related to biological information.

  The biometric information measurement process shown in FIG. 16 is different from the biometric information measurement process of the biometric information measurement apparatus 10 according to the first embodiment shown in FIG. 15 in that step S105 is added. Is the same as FIG.

  For all inflection points detected from the oxygen saturation waveform, step S105 is executed when the magnitude of the slope of the waveform corresponding to the inflection point is compared with the matching condition.

In step S105, CPU 21 determines whether the reliability D is confidence threshold D _x or more. The reliability threshold value _Dx is, for example, a threshold value indicating whether or not the measured oxygen saturation waveform is suitable as a waveform used for measuring cardiac output. As already described, as an example here, the reliability D indicates that the measurement accuracy of the measured cardiac output decreases as the value of the reliability D increases. Therefore, indicating that reliability D is equal to or greater than the reliability threshold value D _x, the measured oxygen saturation waveform, unsuitable as a waveform used for the measurement of cardiac output.

Such a reliability threshold value _Dx is obtained in advance by an experiment with an actual device of the biological information measuring apparatus 10A, a computer simulation based on a design specification of the biological information measuring apparatus 10A, or the like, and is stored in advance in the nonvolatile memory 24, for example.

Therefore, when the reliability D is equal to or higher than the reliability threshold D _x , the CPU 21 performs measurement of LFCT (step S110) used for measurement of cardiac output (step S110) and measurement of cardiac output (step S120). Instead, the process proceeds to step S130. In step S <b> 130, the CPU 21 displays the reliability D on the display unit 28. In this case, the CPU 21 displays, together with the reliability D, a message notifying the measurement status of the biological information such as “the measurement of cardiac output has been stopped” on the display unit 28, and the biological information measuring apparatus 10. The user may be notified. This prompts remeasurement of cardiac output. Such a message is also an example of an index representing the degree of conformity or nonconformity of the oxygen saturation waveform with respect to the measurement of biological information.

Incidentally, the reliability D is in the case of less than the confidence threshold D _x is measured and the measurement of cardiac output LFCT like biological information measuring device 10 according to the first embodiment is executed.

In the example of the biological information measuring apparatus 10A shown in FIG. 16, the reliability D and the reliability are compared after comparing the respective conditions related to the oxygen saturation waveform defined in the conforming condition with the measured oxygen saturation waveform. comparing the threshold D _x, but compared locations of reliability D and confidence threshold D _x is not limited to this.

For example, every time the measured oxygen saturation waveform is compared with each condition relating to the oxygen saturation waveform defined in the conforming condition, the reliability D is compared with the reliability threshold _Dx , and the reliability D is for more confidence threshold D _x, it may proceed to step S130. Specifically, during the steps S40 and S50, between step S60 and S70, and between step S90 and S100, may be compared respectively with reliability D a confidence threshold D _x. In this case, it is notified that the measurement of the cardiac output is stopped at an earlier stage as compared with the case where the reliability D and the reliability threshold _Dx are compared in step S105.

Further, in the example of the biological information measuring device 10A shown in FIG. 16, CPU 21 is to compare the reliability D and confidence threshold D _x, if the reliability D is equal to or greater than the confidence threshold D _x, cardiac output Although the measurement was stopped autonomously, the trigger for stopping the measurement of cardiac output is not limited to this.

  For example, every time the reliability D is updated, the CPU 21 displays the reliability D on the display unit 28, and measures the cardiac output according to an instruction from the user of the biological information measuring device 10A that grasps the reliability D. You may make it cancel. Specifically, the CPU 21 stops measuring the cardiac output when receiving a stop instruction to stop measuring the cardiac output by the operation of the input unit 27 by the user of the biological information measuring apparatus 10A. .

Further, the CPU 21 stores the value of the oxygen saturation measured in each of the plurality of periods in the nonvolatile memory 24, and the cardiac output is determined by the operation of the input unit 27 by the user of the biological information measuring device 10A. When the measurement start instruction is accepted, the cardiac output is measured using only the oxygen saturation waveform suitable for the cardiac output measurement out of the oxygen saturation stored in the nonvolatile memory 24. Also good. Specifically, even when cardiac output is measured using statistics (for example, average value) of each LFCT obtained from a plurality of oxygen saturation waveforms whose reliability D is less than the reliability threshold D _x. Good.

  Such measurement of cardiac output is used for applications such as confirming the tendency of cardiac output during sleep of the measurement subject after the measurement subject wakes up.

According to the biological information measuring apparatus 10A according to the second embodiment, even in the middle of the biological information measurement process when the reliability D becomes confidence threshold D _x or more, the cardiac output Stop measurement.

  Although the present invention has been described above using each embodiment, the present invention is not limited to the scope described in each embodiment. Various modifications or improvements can be added to the respective embodiments without departing from the gist of the present invention, and embodiments to which the modifications or improvements are added are also included in the technical scope of the present invention. For example, the processing order may be changed without departing from the scope of the present invention.

  In each of the embodiments, the form in which the biological information measurement process is realized by software has been described as an example. However, the process equivalent to the flowcharts illustrated in FIGS. 15 and 16 is applied to, for example, an ASIC (Application Specific Integrated Circuit). It may be implemented and processed by hardware. In this case, the detection process can be speeded up.

  Moreover, although each embodiment mentioned above demonstrated the form in which the biometric information measurement program was installed in ROM22, it is not limited to this. The biological information measurement program according to the present invention can be provided in a form recorded in a computer-readable storage medium. For example, the biological information measurement program according to the present invention may be provided in a form recorded on an optical disc such as a CD (Compact Disc) -ROM or a DVD (Digital Versatile Disc) -ROM. The biological information measurement program according to the present invention may be provided in a form recorded in a semiconductor memory such as a USB memory and a flash memory. Furthermore, the biological information measuring devices 10 and 10A may acquire the biological information measuring program according to the present invention from an external device connected to the communication line via the communication unit 29.

In each of the above-described embodiments, the cardiac output, the cardiac coefficient, and the stroke volume are described as examples of biological information related to the oxygen circulation time measured by the biological information measuring device 10. The oxygen circulation time itself may be biological information related to the oxygen circulation time. That is, when measuring the oxygen circulation time based on a waveform representing a change in the value representing the oxygen concentration in the blood, an indicator representing the degree of conformity or nonconformity of the waveform may be reported according to a predetermined condition. .

DESCRIPTION OF SYMBOLS 1 (1A, 1B) ... Light emitting element 3 ... Light receiving element 4 ... Artery 5 ... Vein 6 ... Capillary blood vessel 8 ... Living body 10 (10A) ... Biological information measuring device 11 ... Photoelectric sensor 12 ... Pulse wave processing unit 13 ... Respiration waveform extraction unit 14 ... Oxygen saturation measurement unit 15 ... Timer 16 ... Notification unit 17 ... Oxygen circulation time measurement unit 18 ... cardiac output measuring unit 20 ... computer 21 ... CPU
22 ... ROM
23 ... RAM
24 ... Non-volatile memory 27 ... Input unit 28 ... Display unit 29 ... Communication unit 98 ... Red region 99 ... Infrared region D ... Reliability

Claims (13)

Measuring means for measuring a value representing the oxygen concentration in the blood of the subject;
When measuring biological information related to oxygen circulation time using a waveform representing a change in the value measured by the measuring means, the degree of conformity or nonconformity of the waveform with respect to the measurement of the biological information is determined according to a predetermined condition. An informing means for informing an index to be represented;
A biological information measuring device comprising: The biological information measuring apparatus according to claim 1, wherein the waveform condition suitable for measuring the biological information is defined as the predetermined condition. The biological information measuring device according to claim 1, wherein the waveform condition that is not suitable for the measurement of the biological information is defined as the predetermined condition. The predetermined condition includes the number of inflection points in the waveform,
The biological information measuring device according to claim 2, wherein the notification unit notifies the index according to the number of inflection points in the waveform according to the predetermined condition. The predetermined condition includes the magnitude of the value at the inflection point of the waveform,
The biological information measurement according to any one of claims 2 to 4, wherein the notification means notifies the index corresponding to the magnitude of the value at the inflection point of the waveform according to the predetermined condition. apparatus. The predetermined condition includes the slope of the waveform,
The biological information measuring apparatus according to any one of claims 2 to 5, wherein the notifying unit notifies the index according to the magnitude of the inclination of the waveform in accordance with the predetermined condition. The predetermined condition includes the degree of variation in the slope of the waveform,
The biological information measuring device according to any one of claims 2 to 6, wherein the notifying unit notifies the index according to a degree of variation in the inclination of the waveform according to the predetermined condition. The predetermined condition includes information on the appearance position of the inflection point in the waveform,
The biological information measuring apparatus according to any one of claims 2 to 7, wherein the notifying unit notifies the index according to the appearance position of an inflection point in the waveform according to the predetermined condition. The predetermined condition is set for a plurality of periods divided according to the respiratory state of the measurement subject,
The biological information measuring device according to any one of claims 2 to 8, wherein the notification unit notifies the indicator in at least one of the periods according to the predetermined condition. The biological information according to any one of claims 1 to 9, wherein the measurement unit stops measuring the value when the index indicates that the waveform is not suitable for the measurement of the biological information. measuring device. Comprising a receiving means for receiving an instruction from the measurement person or a measurement person who measures the biological information of the measurement person;
The biological information measuring apparatus according to claim 10, wherein the measuring unit stops measuring the value when the receiving unit receives an instruction to stop measuring the biological information. The living body according to any one of claims 1 to 11, further comprising an information measuring unit that measures the living body information using the waveform that is indicated by the index to be suitable for the measurement of the living body information. Information measuring device.   The biological information measurement program for functioning a computer as each means of the biological information measuring device of any one of Claims 1-12.