Patent ID: 12239440

DETAILED DESCRIPTION

Examples of an embodiment will be described in detail below with reference to the accompanying drawings. In the accompanying drawings, a scale is appropriately changed in order to make each member have a recognizable size.

FIG.1exemplifies a configuration of a pulse photometry system10according to an embodiment. The pulse photometry system10can include a probe20and a pulse photometer30.

The probe20can include a first light-emitting portion211, a second light-emitting portion212, a third light-emitting portion213, a fourth light-emitting portion214, a fifth light-emitting portion215, a sixth light-emitting portion216, a seventh light-emitting portion217, and an eighth light-emitting portion218. Each of the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, and the eighth light-emitting portion218can include a light emitter. Examples of the light emitter include a light-emitting diode (LED), a laser diode (LD), and an EL element.

The first light-emitting portion211is configured to emit first light L1having a first wavelength λ1. The first light-emitting portion211may include a light emitter that emits light having the first wavelength λ1, or may be configured to emit light having the first wavelength λ1by causing light having a wavelength different from the first wavelength λ1emitted from the light emitter to pass through an appropriate optical element.

The second light-emitting portion212is configured to emit second light L2having a second wavelength λ2. The second light-emitting portion212may include a light emitter that emits light having the second wavelength λ2, or may be configured to emit light having the second wavelength λ2by causing light having a wavelength different from the second wavelength λ2emitted from a light emitter to pass through an appropriate optical element.

The third light-emitting portion213is configured to emit third light L3having a third wavelength λ3. The third light-emitting portion213may include a light emitter that emits light having the third wavelength λ3, or may be configured to emit light having the third wavelength λ3by causing light having a wavelength different from the third wavelength λ3emitted from a light emitter to pass through an appropriate optical element.

The fourth light-emitting portion214is configured to emit fourth light L4having a fourth wavelength λ4. The fourth light-emitting portion214may include a light emitter that emits light having the fourth wavelength λ4, or may be configured to emit light having the fourth wavelength λ4by causing light having a wavelength different from the fourth wavelength λ4emitted from a light emitter to pass through an appropriate optical element.

The fifth light-emitting portion215is configured to emit fifth light L5having a fifth wavelength λ5. The fifth light-emitting portion215may include a light emitter that emits light having the fifth wavelength λ5, or may be configured to emit light having the fifth wavelength λ5by causing light having a wavelength different from the fifth wavelength λ5emitted from a light emitter to pass through an appropriate optical element.

The sixth light-emitting portion216is configured to emit sixth light L6having a sixth wavelength λ6. The sixth light-emitting portion216include a light emitter that emits light having the sixth wavelength λ6, or may be configured to emit light having the sixth wavelength λ6by causing light having a wavelength different from the sixth wavelength λ6emitted from a light emitter to pass through an appropriate optical element.

The seventh light-emitting portion217is configured to emit seventh light L7having a seventh wavelength λ7. The seventh light-emitting portion217include a light emitter that emits light having the seventh wavelength λ7, or may be configured to emit light having the seventh wavelength λ7by causing light having a wavelength different from the seventh wavelength λ7emitted from a light emitter to pass through an appropriate optical element.

The eighth light-emitting portion218is configured to emit eighth light L8having an eighth wavelength λ8. The eighth light-emitting portion218may include a light emitter that emits light having the eighth wavelength λ8, or may be configured to emit light having the eighth wavelength λ8by causing light having a wavelength different from the eighth wavelength λ8emitted from a light emitter to pass through an appropriate optical element.

The first wavelength λ1, the second wavelength λ2, the third wavelength λ3, the fourth wavelength λ4, the fifth wavelength λ5, the sixth wavelength λ6, the seventh wavelength λ7, and the eighth wavelength λ8are different from one another.

The probe20can include a light-detecting portion22. The light-detecting portion22can include a light detector that outputs a detection signal corresponding to an intensity of incident light. The detection signal may be an analog signal or a digital signal. Examples of the light detector include a photodiode, a phototransistor, and a photoresistor that are sensitive to at least the first wavelength λ1, the second wavelength λ2, the third wavelength λ3, the fourth wavelength λ4, the fifth wavelength λ5, the sixth wavelength λ6, the seventh wavelength λ7, and the eighth wavelength λ8.

The probe20is attachable to a body40of a patient. In this example, the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, the eighth light-emitting portion218, and the light-detecting portion22are arranged such that the first light L1, the second light L2, the third light L3, the fourth light L4, the fifth light L5, the sixth light L6, the seventh light L7, and the eighth light L8pass through the body40and are incident on the light-detecting portion22.

The first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, the eighth light-emitting portion218, and the light-detecting portion22may be arranged such that the first light L1, the second light L2, the third light L3, the fourth light L4, the fifth light L5, the sixth light L6, the seventh light L7, and the eighth light L8are reflected by the body40and incident on the light-detecting portion22.

The pulse photometer30can include a processor31, an output interface32, and an input interface33.

The processor31is configured to control turn-on and turn-off operations of each of the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, and the eighth light-emitting portion218.

Specifically, the processor31allows a first control signal CS1, a second control signal CS2, a third control signal CS3, a fourth control signal CS4, a fifth control signal CS5, a sixth control signal CS6, a seventh control signal CS7, and an eighth control signal CS8to be output from the output interface32.

The first control signal CS1causes the first light-emitting portion211to emit the first light L1. The second control signal CS2causes the second light-emitting portion212to emit the second light L2. The third control signal CS3causes the third light-emitting portion213to emit the third light L3. The fourth control signal CS4causes the fourth light-emitting portion214to emit the fourth light L4. The fifth control signal CS5causes the fifth light-emitting portion215to emit the fifth light L5. The sixth control signal CS6causes the sixth light-emitting portion216to emit the sixth light L6. The seventh control signal CS7causes the seventh light-emitting portion217to emit the seventh light L7. The eighth control signal CS8causes the eighth light-emitting portion218to emit the eighth light L8.

Each of the first control signal CS1, the second control signal CS2, the third control signal CS3, the fourth control signal CS4, the fifth control signal CS5, the sixth control signal CS6, the seventh control signal CS7, and the eighth control signal CS8may be an analog signal or a digital signal. When each of the first control signal CS1, the second control signal CS2, the third control signal CS3, the fourth control signal CS4, the fifth control signal CS5, the sixth control signal CS6, the seventh control signal CS7, and the eighth control signal CS8is the analog signal, the output interface32may include an appropriate conversion circuit including a D/A converter.

When the first light L1that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs a first detection signal DS1. When the second light L2that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs a second detection signal DS2. When the third light L3that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs a third detection signal DS3. When the fourth light L4that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs a fourth detection signal DS4. When the fifth light L5that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs a fifth detection signal DS5. When the sixth light L6that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs a sixth detection signal DS6. When the seventh light L7that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs a seventh detection signal DS7. When the eighth light L8that has passed through the body40is incident on the light-detecting portion22, the light-detecting portion22outputs an eighth detection signal DS8.

The input interface33is configured to receive each of the first detection signal DS1, the second detection signal DS2, the third detection signal DS3, the fourth detection signal DS4, the fifth detection signal DS5, the sixth detection signal DS6, the seventh detection signal DS7, and the eighth detection signal DS8output from the light-detecting portion22. When each of the first detection signal DS1, the second detection signal DS2, the third detection signal DS3, the fourth detection signal DS4, the fifth detection signal DS5, the sixth detection signal DS6, the seventh detection signal DS7, and the eighth detection signal DS8is the analog signal, the input interface33can include an appropriate conversion circuit including an A/D converter.

FIG.2illustrates an example of an arrangement of the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, and the eighth light-emitting portion218in the probe20.

The first light-emitting portion211can have a first light-emitting surface211a. The first light-emitting surface211ais a surface from which light emitted from a light emitter provided in the first light-emitting portion211is emitted, and forms a part of an outer surface of the probe20.

The second light-emitting portion212can have a second light-emitting surface212a. The second light-emitting surface212ais a surface from which light emitted from a light emitter provided in the second light-emitting portion212is emitted, and forms a part of the outer surface of the probe20.

The third light-emitting portion213can have a third light-emitting surface213a. The third light-emitting surface213ais a surface from which light emitted from a light emitter provided in the third light-emitting portion213is emitted, and forms a part of the outer surface of the probe20.

The fourth light-emitting portion214can have a fourth light-emitting surface214a. The fourth light-emitting surface214ais a surface from which light emitted from a light emitter provided in the fourth light-emitting portion214is emitted, and forms a part of the outer surface of the probe20.

The fifth light-emitting portion215can have a fifth light-emitting surface215a. The fifth light-emitting surface215ais a surface from which light emitted from a light emitter provided in the fifth light-emitting portion215is emitted, and forms a part of the outer surface of the probe20.

The sixth light-emitting portion216can have a sixth light-emitting surface216a. The sixth light-emitting surface216ais a surface from which light emitted from a light emitter provided in the sixth light-emitting portion216is emitted, and forms a part of the outer surface of the probe20.

The seventh light-emitting portion217can have a seventh light-emitting surface217a. The seventh light-emitting surface217ais a surface from which light emitted from a light emitter provided in the seventh light-emitting portion217is emitted, and forms a part of the outer surface of the probe20.

The eighth light-emitting portion218can have an eighth light-emitting surface218a. The eighth light-emitting surface218ais a surface from which light emitted from a light emitter provided in the eighth light-emitting portion218is emitted, and forms a part of the outer surface of the probe20.

FIG.3exemplifies an appearance of a part of the probe20when viewed from a direction of an arrow III inFIG.2. A first normal line N1, a fifth normal line N5, a seventh normal line N7, and an eighth normal line N8can be defined for the first light-emitting surface211a, the fifth light-emitting surface215a, the seventh light-emitting surface217a, and the eighth light-emitting surface218a, respectively. Although not illustrated, a second normal line N2, a third normal line N3, a fourth normal line N4, and a sixth normal line N6can also be defined for the second light-emitting surface212a, the third light-emitting surface213a, the fourth light-emitting surface214a, and the sixth light-emitting surface216a, respectively.

That is,FIG.2exemplifies an appearance of the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, and the eighth light-emitting portion218when viewed from directions along the first normal line N1, the second normal line N2, the third normal line N3, the fourth normal line N4, the fifth normal line N5, the sixth normal line N6, the seventh normal line N7, and the eighth normal line N8. When viewed from the same direction, the first light-emitting surface211a, the second light-emitting surface212a, the third light-emitting surface213a, the fourth light-emitting surface214a, the fifth light-emitting surface215a, the sixth light-emitting surface216a, the seventh light-emitting surface217a, and the eighth light-emitting surface218ahave the same shape.

The first light-emitting portion211can have a first reference point211b. The first reference point211bis defined as a central portion of the first light-emitting surface211awhen viewed from a direction in which the first normal line N1extends.

The second light-emitting portion212can have a second reference point212b. The second reference point212bis defined as a central portion of the second light-emitting surface212awhen viewed from a direction in which the second normal line N2extends.

The third light-emitting portion213can have a third reference point213b. The third reference point213bis defined as a central portion of the third light-emitting surface213awhen viewed from a direction in which the third normal line N3extends.

The fourth light-emitting portion214can have a fourth reference point214b. The fourth reference point214bis defined as a central portion of the fourth light-emitting surface214awhen viewed from a direction in which the fourth normal line N4extends.

The fifth light-emitting portion215can have a fifth reference point215b. The fifth reference point215bis defined as a central portion of the fifth light-emitting surface215awhen viewed from a direction in which the fifth normal line N5extends.

The sixth light-emitting portion216can have a sixth reference point216b. The sixth reference point216bis defined as a central portion of the sixth light-emitting surface216awhen viewed from a direction in which the sixth normal line N6extends.

The seventh light-emitting portion217can have a seventh reference point217b. The seventh reference point217bis defined as a central portion of the seventh light-emitting surface217awhen viewed from a direction in which the seventh normal line N7extends.

The eighth light-emitting portion218can have an eighth reference point218b. The eighth reference point218bis defined as a central portion of the eighth light-emitting surface218awhen viewed from a direction in which the eighth normal line N8extends.

However, the first reference point211b, the second reference point212b, the third reference point213b, the fourth reference point214b, the fifth reference point215b, the sixth reference point216b, the seventh reference point217b, and the eighth reference point218bmay be defined at appropriate positions as long as the same conditions are satisfied for each light-emitting surface. For example, an upper right corner of each light-emitting surface may be defined as the reference point.

An example of an operation of the pulse photometry system10configured as described above will be described with reference toFIG.4. In this example, the pulse photometer30calculates a concentration Φo of oxyhemoglobin (O2Hb) and a concentration Φc of carboxyhemoglobin (COHb). The oxyhemoglobin is an example of a first light-absorbing substance in blood. The carboxyhemoglobin is an example of a second light-absorbing substance in blood.

In this example, in order to calculate the concentration Φo of the oxyhemoglobin, the first light-emitting portion211and the second light-emitting portion212are used. The oxyhemoglobin has wavelength dependence on an absorbance. The first wavelength λ1and the second wavelength λ2are determined as two wavelengths at which a significant difference appears in the absorbance of the oxyhemoglobin. The first wavelength λ1is an example of the first wavelength used for calculating a concentration of a first light absorber. The second wavelength λ2is an example of the second wavelength used for calculating the concentration of the first light absorber.

The first light L1emitted from the first light-emitting portion211is absorbed by arterial blood, venous blood, tissue, or the like when passing through the body40of the patient. Therefore, an intensity of the first light L1incident on the light-detecting portion22is lower than an intensity during emission from the first light-emitting portion211. That is, an absorbance A1of the first light L1can be defined as a ratio between an intensity of light emitted from the first light-emitting portion211and an intensity of light incident on the light-detecting portion22.

Same or similarly, the second light L2emitted from the second light-emitting portion212is absorbed by the arterial blood, the venous blood, the tissue, or the like when passing through the body40of the patient. Therefore, an intensity of the second light L2incident on the light-detecting portion22is lower than an intensity during emission from the first light-emitting portion211. That is, an absorbance A2of the second light L2can be defined as a ratio between an intensity of light emitted from the second light-emitting portion212and an intensity of light incident on the light-detecting portion22.

An arterial blood vessel pulsates with pulsation of a heart of the patient to change thickness of the arterial blood vessel through which the first light L1and the second light L2pass changes. In other words, an amount of the arterial blood that absorbs the first light L1and the second light L2changes. Therefore, with pulsation of blood of the patient, the intensity of the first light L1incident on the light-detecting portion22and the intensity of the second light L2incident on the light-detecting portion22change, and the absorbance A1of the first light L1and the absorbance A2of the second light L2change. A change amount of each absorbance is defined as a first change amount ΔA1and a second change amount ΔA2.

The concentration Φo of the oxyhemoglobin is calculated based on a ratio (ΔA1/ΔA2) between the first change amount ΔA1and the second change amount ΔA2. That is, the processor31of the pulse photometer30calculates the concentration Φo of the oxyhemoglobin based on the first detection signal DS1and the second detection signal DS2output from the light-detecting portion22.

The processor31can output a signal OS corresponding to the concentration Φo of the oxyhemoglobin from the output interface32. The signal is subjected to an appropriate processing. Examples of such a processing include calculation of a value that can be acquired based on the concentration Φo, display of at least one of a value of the concentration Φo and the value acquired based on the concentration Φo, and a notification operation based on at least one of the value of the concentration Φo and the value acquired based on the concentration Φo. Examples of the value that can be acquired based on the concentration Φo include percutaneous arterial oxygen saturation (SpO2).

In this example, in order to calculate the concentration Φc of the carboxyhemoglobin, the third light-emitting portion213and the fourth light-emitting portion214are used. The carboxyhemoglobin has wavelength dependence on an absorbance. The third wavelength λ3and the fourth wavelength λ4are determined as two wavelengths at which a significant difference appears in the absorbance of the carboxyhemoglobin. The fourth wavelength λ4is an example of the third wavelength not used for calculating the concentration of the first light-absorbing substance. The fourth wavelength λ4is also an example of the third wavelength used for calculating the concentration of the second light-absorbing substance. The third wavelength λ3is an example of the fourth wavelength not used for calculating the concentration of the first light-absorbing substance. The third wavelength λ3is also an example of the fourth wavelength used for calculating the concentration of the second light-absorbing substance.

Also, for the third light L3and the fourth light L4, an absorbance A3and an absorbance A4accompanying the passage through the body40of the patient can be obtained, and a third change amount ΔA3and a fourth change amount ΔA4accompanying the pulsation can be defined. The concentration Φc of the carboxyhemoglobin is calculated based on a ratio (ΔA3/ΔA4) between the third change amount ΔA3and the fourth change amount ΔA4. That is, the processor31of the pulse photometer30calculates the concentration Φc of the carboxyhemoglobin based on the third detection signal DS3and the fourth detection signal DS4output from the light-detecting portion22.

The processor31can output a signal OS corresponding to the concentration Φc of the carboxyhemoglobin from the output interface32. The signal OS is subjected to an appropriate processing. Examples of such a processing include calculation of a value that can be acquired based on the concentration Φc, display of at least one of a value of the concentration Φc and the value acquired based on the concentration Φc, and a notification operation based on at least one of the value of the concentration Φc and the value acquired based on the concentration Φc.

In this example, the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, and the fourth light-emitting portion214are arranged so as to satisfy the following conditions.A distance D12between the first reference point211band the second reference point212bis shorter than a distance D41between the fourth reference point214band the first reference point211b.The distance D12between the first reference point211band the second reference point212bis shorter than a distance D42between the fourth reference point214band the second reference point212b.A distance D43between the fourth reference point214band the third reference point213bis shorter than the distance D41between the fourth reference point214band the first reference point211b.The distance D43between the fourth reference point214band the third reference point213bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

According to the above-described configuration, the first light-emitting portion211and the second light-emitting portion212used to calculate the concentration Φo of the oxyhemoglobin can be arranged closer to each other, and the third light-emitting portion213and the fourth light-emitting portion214used to calculate the concentration Φc of the carboxyhemoglobin can be arranged closer to each other.

Accordingly, for each of the concentration Φo of the oxyhemoglobin and the concentration Φc of the carboxyhemoglobin, an influence of a difference in an optical path length from a plurality of light-emitting portions to the light-detecting portion22used for calculation on a change in an absorbance due to the pulsation can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

As exemplified inFIG.5, the seventh light-emitting portion217can be used to calculate the concentration Φc of the carboxyhemoglobin. The seventh wavelength λ7is determined as a wavelength at which a significant difference appears in the absorbance of the carboxyhemoglobin with respect to at least one of the third wavelength λ3and the fourth wavelength λ4. The seventh wavelength λ7is an example of the fourth wavelength not used for calculating the concentration of the first light-absorbing substance. The seventh wavelength λ7is also an example of the fourth wavelength used for calculating the concentration of the second light-absorbing substance. Also, for the seventh light L7, an absorbance A7accompanying the passage through the body40of the patient can be obtained, and a seventh change amount ΔA7accompanying the pulsation can be defined.

The seventh light-emitting portion217may be used in addition to the third light-emitting portion213and the fourth light-emitting portion214, or may be used in place of one of the third light-emitting portion213and the fourth light-emitting portion214. In the former case, by using the seventh change amount ΔA7as an offset term for a calculation result of the ratio between the third change amount ΔA3and the fourth change amount ΔA4, it is possible to prevent an influence of other light-absorbing substances and to improve calculation accuracy of the concentration Φc of the carboxyhemoglobin. In the latter case, when the concentration Φc of the carboxyhemoglobin cannot be appropriately calculated by the third light-emitting portion213and the fourth light-emitting portion214due to various reasons, it is possible to attempt to calculate the concentration Φc of the carboxyhemoglobin by using the seventh light-emitting portion217as an alternative light source.

In this example, the first light-emitting portion211, the second light-emitting portion212, the fourth light-emitting portion214, and the seventh light-emitting portion217are arranged so as to satisfy the following conditions.The distance D12between the first reference point211band the second reference point212bis shorter than the distance D41between the fourth reference point214band the first reference point211b.The distance D12between the first reference point211band the second reference point212bis shorter than the distance D42between the fourth reference point214band the second reference point212b.A distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D41between the fourth reference point214band the first reference point211b.The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

According to the above-described configuration, the first light-emitting portion211and the second light-emitting portion212used to calculate the concentration Φo of the oxyhemoglobin can be arranged closer to each other, and the fourth light-emitting portion214and the seventh light-emitting portion217used to calculate the concentration Φc of the carboxyhemoglobin can be arranged closer to each other.

Accordingly, for each of the concentration Φo of the oxyhemoglobin and the concentration Φc of the carboxyhemoglobin, an influence of a difference in an optical path length from a plurality of light-emitting portions to the light-detecting portion22used for calculation on a change in an absorbance due to the pulsation can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the blood light absorber by pulse photometry.

FIG.6illustrates another example of the operation of the pulse photometry system10. In this example, the pulse photometer30calculates a concentration Φr of deoxyhemoglobin (RHb). The deoxyhemoglobin is an example of the first light-absorbing substance in blood.

In this example, in order to calculate the concentration Φr of the deoxyhemoglobin, the third light-emitting portion213and the eighth light-emitting portion218are used. The deoxyhemoglobin has wavelength dependence on an absorbance. The eighth wavelength λ8is determined as a wavelength at which a significant difference appears in an absorbance of the deoxyhemoglobin with respect to the third wavelength λ3. The third wavelength λ3is an example of the first wavelength used for calculating the concentration of the first light absorber. The eighth wavelength λ8is an example of the second wavelength used for calculating the concentration of the first light absorber.

Also, for the eighth light L8, an absorbance A8accompanying the passage through the body40of the patient can be obtained, and an eighth change amount ΔA8accompanying the pulsation can be defined. The concentration Φr of the deoxyhemoglobin is calculated based on a ratio (ΔA3/ΔA8) between the third change amount ΔA3and the eighth change amount ΔA8. That is, the processor31of the pulse photometer30calculates the concentration Φr of the deoxyhemoglobin based on the third detection signal DS3and the eighth detection signal DS8output from the light-detecting portion22.

The processor31can output a signal OS corresponding to the concentration Φr of the deoxyhemoglobin from the output interface32. The signal OS is subjected to an appropriate processing. Examples of such a processing include calculation of a value that can be acquired based on the concentration Φr, display of at least one of a value of the concentration Φr and the value acquired based on the concentration Φr, and a notification operation based on at least one of the value of the concentration Φr and the value acquired based on the concentration Φr. When it is assumed that there is no abnormal hemoglobin such as carboxyhemoglobin or methemoglobin in hemoglobin in the arterial blood, the concentration of the oxyhemoglobin can be specified by specifying the concentration of the deoxyhemoglobin. In this case, examples of the value that can be acquired based on the concentration Φr include the percutaneous arterial oxygen saturation (SpO2).

In a case where it can be assumed that two types of light absorbers exist in a blood system, another example of the relationship in which one concentration can be specified and the other concentration can be specified is a relationship between a concentration of total hemoglobin and a concentration of water in blood.

In this example, at least one of the fifth light-emitting portion215and the sixth light-emitting portion216is used to determine an attachment state of the probe20to the body40of the patient. For example, when at least one of an intensity of the fifth light L5incident on the light-detecting portion22and an intensity of the sixth light L6incident on the light-detecting portion22is smaller than a threshold, the processor31of the pulse photometer30determines that the attachment state of the probe20to the body40of the patient is not appropriate. Each of the fifth wavelength λ5and the sixth wavelength λ6is an example of the third wavelength not used for calculating the concentration of the first light-absorbing substance.

In this example, the fifth light-emitting portion215, the sixth light-emitting portion216, the third light-emitting portion213, and the eighth light-emitting portion218are arranged so as to satisfy the following conditions.A distance D38between the third reference point213band the eighth reference point218bis shorter than a distance D35between the third reference point213band the fifth reference point215b.The distance D38between the third reference point213band the eighth reference point218bis shorter than a distance D36between the third reference point213band the sixth reference point216b.

According to the above-described configuration, an influence of light emitted from a light-emitting portion not used for calculating the concentration Φr of the deoxyhemoglobin on a light-emitting portion used for calculating the concentration Φr of the deoxyhemoglobin can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

As exemplified inFIG.7, the seventh light-emitting portion217can be used to calculate the concentration Φr of the deoxyhemoglobin. The seventh wavelength λ7is determined as a wavelength at which a significant difference appears in the absorbance of the deoxyhemoglobin with respect to at least one of the third wavelength λ3and the eighth wavelength λ8. The seventh wavelength λ7is an example of the second wavelength used for calculating the concentration of the first light absorber.

The seventh light-emitting portion217may be used in addition to the third light-emitting portion213and the eighth light-emitting portion218, or may be used in place of one of the third light-emitting portion213and the eighth light-emitting portion218. In the former case, by using the seventh change amount ΔA7as an offset term for a calculation result of the ratio between the third change amount ΔA3and the eighth change amount ΔA8, it is possible to prevent an influence of other light-absorbing substances and to improve calculation accuracy of the concentration Φr of the deoxyhemoglobin. In the latter case, when the concentration Φr of the deoxyhemoglobin cannot be appropriately calculated by the third light-emitting portion213and the eighth light-emitting portion218due to various reasons, it is possible to attempt to calculate the concentration Φr of the deoxyhemoglobin by using the seventh light-emitting portion217as an alternative light source.

In this example, the fifth light-emitting portion215, the sixth light-emitting portion216, the third light-emitting portion213, and the seventh light-emitting portion217are arranged so as to satisfy the following conditions.A distance D37between the third reference point213band the seventh reference point217bis shorter than the distance D35between the third reference point213band the fifth reference point215b.The distance D37between the third reference point213band the seventh reference point217bis shorter than the distance D36between the third reference point213band the sixth reference point216b.

According to the above-described configuration as well, an influence of light emitted from a light-emitting portion not used for calculating the concentration Φr of the deoxyhemoglobin on a light-emitting portion used for calculating the concentration Φr of the deoxyhemoglobin can also be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

FIG.8illustrates another example of the operation of the pulse photometry system10. In this example, the pulse photometer30calculates the concentration Φo of the oxyhemoglobin (O2Hb) and a concentration Φm of the methemoglobin (MetHb). The oxyhemoglobin is an example of the first light-absorbing substance in blood. The methemoglobin is an example of the second light-absorbing substance in blood.

In this example, in order to calculate the concentration Φo of the oxyhemoglobin, the first light-emitting portion211and the second light-emitting portion212are used. Since the calculation method is the same as the example described with reference toFIGS.4and5, the repeated description will be omitted.

In this example, in order to calculate the concentration Φm of the methemoglobin, the fourth light-emitting portion214and the eighth light-emitting portion218are used. The methemoglobin has wavelength dependence on an absorbance. The fourth wavelength λ4and the eighth wavelength λ8are determined as two wavelengths at which a significant difference appears in the absorbance of the methemoglobin. The fourth wavelength λ4is an example of the third wavelength not used for calculating the concentration of the first light-absorbing substance. The fourth wavelength λ4is also an example of the third wavelength used for calculating the concentration of the second light-absorbing substance. The eighth wavelength λ8is an example of the fourth wavelength not used for calculating the concentration of the first light-absorbing substance. The eighth wavelength λ8is also an example of the fourth wavelength used for calculating the concentration of the second light-absorbing substance.

The concentration Φm of the methemoglobin is calculated based on a ratio (ΔA4/ΔA8) between the fourth change amount ΔA4and the eighth change amount ΔA8. That is, the processor31of the pulse photometer30calculates the concentration Φm of the methemoglobin based on the fourth detection signal DS4and the eighth detection signal DS8output from the light-detecting portion22.

The processor31can output a signal OS corresponding to the concentration Φm of the methemoglobin from the output interface32. The signal OS is subjected to an appropriate processing. Examples of such a processing include calculation of a value that can be acquired based on the concentration Φm, display of at least one of a value of the concentration Φm and the value acquired based on the concentration Φm, and a notification operation based on at least one of the value of the concentration Φm and the value acquired based on the concentration Φm.

In this example, the first light-emitting portion211, the second light-emitting portion212, the fourth light-emitting portion214, and the eighth light-emitting portion218are arranged so as to satisfy the following conditions.The distance D12between the first reference point211band the second reference point212bis shorter than the distance D41between the fourth reference point214band the first reference point211b.The distance D12between the first reference point211band the second reference point212bis shorter than the distance D42between the fourth reference point214band the second reference point212b.The distance D48between the fourth reference point214band the eighth reference point218bis shorter than the distance D41between the fourth reference point214band the first reference point211b.The distance D48between the fourth reference point214band the eighth reference point218bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

According to the above-described configuration, the first light-emitting portion211and the second light-emitting portion212used to calculate the concentration Φo of the oxyhemoglobin can be arranged closer to each other, and the fourth light-emitting portion214and the eighth light-emitting portion218used to calculate the concentration Φm of the methemoglobin can be arranged closer to each other.

Accordingly, for each of the concentration Φo of the oxyhemoglobin and the concentration Φm of the methemoglobin, an influence of a difference in an optical path length from a plurality of light-emitting portions to the light-detecting portion22used for calculation on a change in an absorbance due to pulsation can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

As exemplified inFIG.9, the seventh light-emitting portion217can be used to calculate the concentration Φm of the methemoglobin. The seventh wavelength λ7is determined as a wavelength at which a significant difference appears in the absorbance of the methemoglobin with respect to at least one of the fourth wavelength λ4and the eighth wavelength λ8. The seventh wavelength λ7is an example of the fourth wavelength not used for calculating the concentration of the first light-absorbing substance. The seventh wavelength λ7is also an example of the fourth wavelength used for calculating the concentration of the second light-absorbing substance.

The seventh light-emitting portion217may be used in addition to the fourth light-emitting portion214and the eighth light-emitting portion218, or may be used in place of one of the fourth light-emitting portion214and the eighth light-emitting portion218. In the former case, by using the seventh change amount ΔA7as an offset term for a calculation result of the ratio between the fourth change amount ΔA4and the eighth change amount ΔA8, it is possible to prevent an influence of other light-absorbing substances and to improve calculation accuracy of the concentration Φm of the methemoglobin. In the latter case, when the concentration Φm of the methemoglobin cannot be appropriately calculated by the fourth light-emitting portion214and the eighth light-emitting portion218due to various reasons, it is possible to attempt to calculate the concentration Φm of the methemoglobin by using the seventh light-emitting portion217as an alternative light source.

In this example, the first light-emitting portion211, the second light-emitting portion212, the fourth light-emitting portion214, and the seventh light-emitting portion217are arranged so as to satisfy the following conditions.The distance D12between the first reference point211band the second reference point212bis shorter than the distance D41between the fourth reference point214band the first reference point211b.The distance D12between the first reference point211band the second reference point212bis shorter than the distance D42between the fourth reference point214band the second reference point212b.The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D41between the fourth reference point214band the first reference point211b.The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

According to the above-described configuration, the first light-emitting portion211and the second light-emitting portion212used to calculate the concentration Φo of the oxyhemoglobin can be arranged closer to each other, and the fourth light-emitting portion214and the seventh light-emitting portion217used to calculate the concentration Φm of the methemoglobin can be arranged closer to each other.

Accordingly, for each of the concentration Φo of the oxyhemoglobin and the concentration Φm of the methemoglobin, an influence of a difference in an optical path length from a plurality of light-emitting portions to the light-detecting portion22used for calculation on a change in an absorbance due to pulsation can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

FIG.10exemplifies a configuration of a semiconductor light emitter210that can be provided in each of the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, and the eighth light-emitting portion218.

The semiconductor light emitter210can include a substrate210a, an N-type semiconductor layer210b, a light-emitting layer210c, a P-type semiconductor layer210d, a P-type transparent electrode210e, a P-side electrode210f, an N-side electrode210g, and a protective film210h.

An upper side inFIG.10corresponds to a side adjacent to a light-emitting surface of each light-emitting portion. In a case of this example, in each light-emitting portion provided in the probe20, the P-type semiconductor layer is disposed on a side adjacent to the light-emitting surface. According to such a configuration, all the light-emitting portions can be efficiently manufactured by a common semiconductor process.

In each light-emitting portion provided in the probe20, the N-type semiconductor layer may be disposed on the side adjacent to the light-emitting surface.

In the example illustrated inFIG.10, both the P-side electrode210fand the N-side electrode210gare arranged on a side facing the light-emitting surface. However, a configuration in which at least one of the P-side electrode210fand the N-side electrode210gis disposed on a side facing the substrate210amay also be adopted.

FIG.11illustrates another example of the arrangement of the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, the fourth light-emitting portion214, the fifth light-emitting portion215, the sixth light-emitting portion216, the seventh light-emitting portion217, and the eighth light-emitting portion218of the probe20.FIG.12exemplifies an appearance of a part of the probe20when viewed from a direction of an arrow XII inFIG.11. Substantially the same components as those in the example shown inFIGS.2and3are denoted by the same reference numerals, and repeated description thereof will be omitted.

FIG.13illustrates an example of the operation of the pulse photometry system10including the probe20configured as exemplified inFIGS.11and12. In this example, the pulse photometer30calculates the concentration Φo of the oxyhemoglobin and the concentration Φc of the carboxyhemoglobin. The oxyhemoglobin is an example of the first light-absorbing substance in blood. The carboxyhemoglobin is an example of the second light-absorbing substance in blood.

In this example, in order to calculate the concentration Φo of the oxyhemoglobin, the first light-emitting portion211and the second light-emitting portion212are used. Since a configuration related to the calculation of the concentration Φo of the oxyhemoglobin is the same as that of the example described with reference toFIG.4, repeated description will be omitted. The first wavelength λ1is an example of the first wavelength used for calculating the concentration of the first light absorber. The second wavelength λ2is an example of the second wavelength used for calculating the concentration of the first light absorber.

In this example, in order to calculate the concentration Φc of the carboxyhemoglobin, the third light-emitting portion213and the fourth light-emitting portion214are used. Since a configuration related to the calculation of the concentration Φc of the carboxyhemoglobin is the same as that of the example described with reference toFIG.4, repeated description will be omitted. The fourth wavelength λ4is an example of the third wavelength not used for calculating the concentration of the first light-absorbing substance. The fourth wavelength λ4is also an example of the third wavelength used for calculating the concentration of the second light-absorbing substance. The third wavelength λ3is an example of the fourth wavelength not used for calculating the concentration of the first light-absorbing substance. The third wavelength λ3is also an example of the fourth wavelength used for calculating the concentration of the second light-absorbing substance.

In this example, the first light-emitting portion211, the second light-emitting portion212, the third light-emitting portion213, and the fourth light-emitting portion214are arranged so as to satisfy the following conditions.

The distance D12between the first reference point211band the second reference point212bis shorter than the distance D41between the fourth reference point214band the first reference point211b.

The distance D12between the first reference point211band the second reference point212bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

The distance D43between the fourth reference point214band the third reference point213bis shorter than the distance D41between the fourth reference point214band the first reference point211b.

The distance D43between the fourth reference point214band the third reference point213bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

According to the above-described configuration, the first light-emitting portion211and the second light-emitting portion212used to calculate the concentration Φo of the oxyhemoglobin can be arranged closer to each other, and the third light-emitting portion213and the fourth light-emitting portion214used to calculate the concentration Φc of the carboxyhemoglobin can be arranged closer to each other.

Accordingly, for each of the concentration Φo of the oxyhemoglobin and the concentration Φc of the carboxyhemoglobin, an influence of a difference in an optical path length from a plurality of light-emitting portions to the light-detecting portion22used for calculation on a change in an absorbance due to the pulsation can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

As exemplified inFIG.14, the seventh light-emitting portion217can be used to calculate the concentration Φc of the carboxyhemoglobin. Since a configuration related to the calculation of the concentration Φc of the carboxyhemoglobin is the same as that of the example described with reference toFIG.5, repeated description will be omitted. The seventh wavelength λ7is an example of the fourth wavelength not used for calculating the concentration of the first light-absorbing substance. The seventh wavelength λ7is also an example of the fourth wavelength used for calculating the concentration of the second light-absorbing substance.

In this example, the first light-emitting portion211, the second light-emitting portion212, the fourth light-emitting portion214, and the seventh light-emitting portion217are arranged so as to satisfy the following conditions.

The distance D12between the first reference point211band the second reference point212bis shorter than the distance D41between the fourth reference point214band the first reference point211b.

The distance D12between the first reference point211band the second reference point212bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D41between the fourth reference point214band the first reference point211b.

The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

According to the above-described configuration, the first light-emitting portion211and the second light-emitting portion212used to calculate the concentration Φo of the oxyhemoglobin can be arranged closer to each other, and the fourth light-emitting portion214and the seventh light-emitting portion217used to calculate the concentration Φc of the carboxyhemoglobin can be arranged closer to each other.

Accordingly, for each of the concentration Φo of the oxyhemoglobin and the concentration Φc of the carboxyhemoglobin, an influence of a difference in an optical path length from a plurality of light-emitting portions to the light-detecting portion22used for calculation on a change in an absorbance due to the pulsation can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

FIG.15illustrates another example of the operation of the pulse photometry system10including the probe20configured as exemplified inFIGS.11and12. In this example, the pulse photometer30calculates the concentration Φr of the deoxyhemoglobin. The deoxyhemoglobin is an example of the first light-absorbing substance in blood.

In this example, in order to calculate the concentration Φr of the deoxyhemoglobin, the third light-emitting portion213and the eighth light-emitting portion218are used. The deoxyhemoglobin has wavelength dependence on an absorbance. Since a configuration related to the calculation of the concentration Φr of the deoxyhemoglobin is the same as that of the example described with reference toFIG.6, repeated description will be omitted. The third wavelength λ3is an example of the first wavelength used for calculating the concentration of the first light absorber. The eighth wavelength λ8is an example of the second wavelength used for calculating the concentration of the first light absorber.

In this example, at least one of the fifth light-emitting portion215and the sixth light-emitting portion216is used to determine an attachment state of the probe20to the body40of the patient. Since a configuration related to determination of the attachment state is the same as that of the example described with reference toFIG.6, repeated description will be omitted. Each of the fifth wavelength λ5and the sixth wavelength λ6is an example of the third wavelength not used for calculating the concentration of the first light-absorbing substance.

In this example, the fifth light-emitting portion215, the sixth light-emitting portion216, the third light-emitting portion213, and the eighth light-emitting portion218are arranged so as to satisfy the following conditions.

The distance D38between the third reference point213band the eighth reference point218bis shorter than the distance D35between the third reference point213band the fifth reference point215b.

The distance D38between the third reference point213band the eighth reference point218bis shorter than the distance D36between the third reference point213band the sixth reference point216b.

According to the above-described configuration, an influence of light emitted from a light-emitting portion not used for calculating the concentration Φr of the deoxyhemoglobin on a light-emitting portion used for calculating the concentration Φr of the deoxyhemoglobin can also be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

As exemplified inFIG.16, the seventh light-emitting portion217can be used to calculate the concentration Φr of the deoxyhemoglobin. Since a configuration related to the calculation of the concentration Φr of the deoxyhemoglobin is the same as that of the example described with reference toFIG.7, repeated description will be omitted. The seventh wavelength λ7is an example of the second wavelength used for calculating the concentration of the first light absorber.

In this example, the fifth light-emitting portion215, the sixth light-emitting portion216, the third light-emitting portion213, and the seventh light-emitting portion217are arranged so as to satisfy the following conditions.

The distance D37between the third reference point213band the seventh reference point217bis shorter than the distance D35between the third reference point213band the fifth reference point215b.

The distance D37between the third reference point213band the seventh reference point217bis shorter than the distance D36between the third reference point213band the sixth reference point216b.

According to the above-described configuration as well, an influence of light emitted from a light-emitting portion not used for calculating the concentration Φr of the deoxyhemoglobin on a light-emitting portion used for calculating the concentration Φr of the deoxyhemoglobin can also be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

FIG.17illustrates another example of the operation of the pulse photometry system10including the probe20configured as exemplified inFIGS.11and12. In this example, the pulse photometer30calculates the concentration Φo of the oxyhemoglobin and the concentration Φm of the methemoglobin. The oxyhemoglobin is an example of the first light-absorbing substance in blood. The methemoglobin is an example of the second light-absorbing substance in blood.

In this example, in order to calculate the concentration Φo of the oxyhemoglobin, the first light-emitting portion211and the second light-emitting portion212are used. Since a configuration related to the calculation of the concentration Φo of the oxyhemoglobin is the same as that of the example described with reference toFIGS.4and5, repeated description will be omitted.

In this example, in order to calculate the concentration Φm of the methemoglobin, the fourth light-emitting portion214and the seventh light-emitting portion217are used. Since a configuration related to the calculation of the concentration Φm of the methemoglobin is the same as that of the example described with reference toFIG.9, repeated description will be omitted. The fourth wavelength λ4is an example of the third wavelength not used for calculating the concentration of the first light-absorbing substance. The fourth wavelength λ4is also an example of the third wavelength used for calculating the concentration of the second light-absorbing substance. The seventh wavelength λ7is an example of the fourth wavelength not used for calculating the concentration of the first light-absorbing substance. The seventh wavelength λ7is also an example of the fourth wavelength used for calculating the concentration of the second light-absorbing substance.

In this example, the first light-emitting portion211, the second light-emitting portion212, the fourth light-emitting portion214, and the seventh light-emitting portion217are arranged so as to satisfy the following conditions.

The distance D12between the first reference point211band the second reference point212bis shorter than the distance D41between the fourth reference point214band the first reference point211b.

The distance D12between the first reference point211band the second reference point212bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D41between the fourth reference point214band the first reference point211b.

The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D42between the fourth reference point214band the second reference point212b.

According to the above-described configuration, the first light-emitting portion211and the second light-emitting portion212used to calculate the concentration Φo of the oxyhemoglobin can be arranged closer to each other, and the fourth light-emitting portion214and the seventh light-emitting portion217used to calculate the concentration Φm of the methemoglobin can be arranged closer to each other.

Accordingly, for each of the concentration Φo of the oxyhemoglobin and the concentration Φm of the methemoglobin, an influence of a difference in an optical path length from a plurality of light-emitting portions to the light-detecting portion22used for calculation on a change in an absorbance due to pulsation can be reduced. Therefore, it is possible to prevent a decrease in calculation accuracy of the concentration of the light-absorbing substance by pulse photometry.

FIG.18illustrates another example of the operation of the pulse photometry system10including the probe20configured as exemplified inFIGS.11and12. In this example, the pulse photometer30calculates the concentration Φc of the carboxyhemoglobin and the concentration Φm of the methemoglobin. The carboxyhemoglobin is an example of the first light-absorbing substance in blood. The methemoglobin is an example of the second light-absorbing substance in blood.

In this example, in order to calculate the concentration Φc of the carboxyhemoglobin, the fourth light-emitting portion214and the seventh light-emitting portion217are used. Since a configuration related to the calculation of the concentration Φc of the carboxyhemoglobin is the same as that of the example described with reference toFIG.5, repeated description will be omitted. The fourth wavelength λ4is an example of the first wavelength used for calculating the concentration of the first light-absorbing substance. The seventh wavelength λ7is an example of the second wavelength used for calculating the concentration of the first light-absorbing substance.

In this example, in order to calculate the concentration Φm of the methemoglobin, the fourth light-emitting portion214and the eighth light-emitting portion218are used. Since a configuration related to the calculation of the concentration Φm of the methemoglobin is the same as that of the example described with reference toFIG.8, repeated description will be omitted. The eighth wavelength λ8is an example of the third wavelength not used for calculating the concentration of the first light-absorbing substance.

In this example, the fourth light-emitting portion214, the seventh light-emitting portion217, and the eighth light-emitting portion218are arranged so as to satisfy the following conditions.The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D48between the fourth reference point214band the eighth reference point218b.

The third light-emitting portion213may be used instead of the eighth light-emitting portion218. In this case, the third light-emitting portion213, the fourth light-emitting portion214, and the seventh light-emitting portion217are arranged so as to satisfy the following conditions.The distance D47between the fourth reference point214band the seventh reference point217bis shorter than the distance D37between the third reference point213band the seventh reference point217b.

For example, a case where importance related to the calculation of the concentration Φc of the carboxyhemoglobin is higher than importance related to the calculation of the concentration Φm of the methemoglobin will be considered. According to the above-described configuration, regarding the concentration Φc of the carboxyhemoglobin, an influence of a difference in an optical path length from the plurality of light-emitting portions to the light-detecting portion22used for the calculation on a change in an absorbance due to the pulsation can be reduced. That is, when some of the plurality of light-emitting portions are used in combination with the calculation of a plurality of concentrations of light absorbers, it is possible to prevent a decrease in calculation accuracy of a concentration of a light absorber having relatively high importance.

The above embodiment is merely an example for facilitating the understanding of the presently disclosed subject matter. The configuration according to the above embodiment can be appropriately changed or improved without departing from the spirit of the presently disclosed subject matter.

The pulse photometry system10may include three or more optional number of light-emitting portions in accordance with the number and type of the plurality of light-absorbing substances for which concentration calculation is required. Examples of other light-absorbing substances may also include bilirubin and glucose.

The light-absorbing substance to be subjected to concentration calculation may include not only a substance generated in the body of the patient, but also pigment injected into a blood vessel for the purpose of cardiac output measurement, liver function measurement, or a contrast examination using indocyanine green (ICG), for example.

In the above embodiment, the plurality of light-emitting portions are arranged at equal intervals. However, an interval between the adjacent light-emitting portions may be appropriately determined in accordance with the number and the type of the light-absorbing substances for which the concentration calculation is required.

The pulse photometer30may be provided as an independent device, or may be implemented as a device that provides a function of calculating a concentration of a light-absorbing substance in a patient monitor that acquires a plurality of types of physiological parameters.