Patent Description:
A pulse oximeter is known as a device for calculating transcutaneous arterial oxygen saturation (SpO<NUM>: hereinafter simply referred to as arterial oxygen saturation) of a subject. A probe electrically connected to the pulse oximeter includes at least one light emitter capable of emitting a red light beam and at least one light emitter capable of emitting an infrared light beam (see Patent Literature <NUM>). An electrocardiogram examination device using a standard <NUM>-lead electrocardiogram is also known. A plurality of electrodes is electrically connected to such an electrocardiogram examination device. When an electrocardiogram examination is performed by the electrocardiogram examination device, four electrodes are attached to the extremities of the subject and six electrodes are attached to the chest of the subject (see Patent Literature <NUM>).

<CIT> deals with multiple wavelength pulse oximetry with sensor redundancy. Its present techniques may provide for reasonably reliable estimates of physiological parameters, such as arterial oxygen saturation, by using a recovery or a limp mode of operation should one or more light emitters of the spectrophotometric system fail or become otherwise inoperative.

<CIT> provides a device and method suitable for monitoring arterial blood in a body part. The disclosed method comprises the steps of determining any one of the sensors or emitters as failing to work properly, disregarding the observations made with the one of the sensors or emitters failing to work properly and regarding the readings of the remaining working sensors to monitor arterial blood.

For example, a conventional pulse oximeter (an example of a physiological parameter calculation device) cannot calculate arterial oxygen saturation (an example of a physiological parameter) when a failure occurs in any emitters of a probe. An electrocardiogram examination device (an example of a physiological parameter calculation device) cannot acquire electrocardiogram information (an example of a physiological parameter) when a failure occurs in any electrodes connected to the electrocardiogram examination device. In this respect, there is room for improvement in the conventional physiological parameter calculation device. Other relevant prior art is disclosed in <CIT>, <CIT>, <CIT>.

It is an object of the present invention to provide a physiological parameter calculation device that is resistant to a failure of a light emitter or the like of a probe, and a computer program and a non-transitory computer-readable medium used for the physiological parameter calculation device.

A physiological parameter calculation device according to a first aspect for achieving the above object includes:.

In addition, a computer program according to a second aspect for achieving the above object causes a computer to implement functions of:.

In addition, in a non-transitory computer-readable medium according to a third aspect for achieving the above object,
the computer program is stored.

According to the above configuration, the calculation section calculates the physiological parameter based on the first algorithm when a failure does not occur in the element for acquiring the signal used for the first algorithm among the plurality of elements for acquiring the physiological information of the subject. On the other hand, the calculation section calculates the physiological parameter based on the second algorithm when a failure occurs in the element for acquiring the signal used for the first algorithm among the plurality of elements for acquiring the physiological information of the subject. Therefore, even if a failure occurs in any elements, the calculation section can calculate the physiological parameter.

As described above, according to the above configuration, it is possible to provide a physiological parameter calculation device having failure resistance against a failure of an element of a sensor for acquiring physiological information of a subject.

According to the present invention, it is possible to provide a physiological parameter calculation device having failure resistance against a failure of a light emitter sensor or the like of a probe, a computer program and a non-transitory computer-readable medium, which are used for the physiological parameter calculation device.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

<FIG> is a diagram illustrating a functional configuration of a physiological parameter calculation system <NUM> according to the present embodiment. As illustrated in <FIG>, the physiological parameter calculation system <NUM> includes a pulse oximeter <NUM> (an example of a physiological parameter calculation device) and a probe <NUM> (an example of a sensor).

The pulse oximeter <NUM> is a device for calculating SpO<NUM> (an example of a physiological parameter) of a subject. SpO<NUM> indicates a ratio of oxyhemoglobin to the amount of hemoglobin that can transport oxygen. As illustrated in <FIG>, the pulse oximeter <NUM> includes an input/output interface <NUM>, a failure sensing section <NUM>, a controller <NUM>, a display <NUM>, and a notifying section <NUM>. These components are connected to each other via a bus <NUM> so as to be able to communicate with each other.

The input/output interface <NUM> includes an acquiring section 11a. The input/output interface <NUM> is, for example, a connector that allows passage of a signal. The pulse oximeter <NUM> can be connected to the probe <NUM> via the input/output interface <NUM> in a wired or wireless manner.

The probe <NUM> can be attached to body tissue <NUM> (a fingertip, an earlobe, or the like) of the subject. As illustrated in <FIG>, the probe <NUM> includes a first light emitter <NUM>, a second light emitter <NUM>, a third light emitter <NUM>, and a detector <NUM>. The probe <NUM> may include a detector other than the detector <NUM>. That is, the probe <NUM> may include a plurality of detectors.

The first light emitter <NUM> is a semiconductor light emitter capable of emitting a first light beam having a first wavelength λ1. The second light emitter <NUM> is a semiconductor light emitter capable of emitting a second light beam having a second wavelength λ2. The third light emitter <NUM> is a semiconductor light emitter capable of emitting a third light beam including having a third wavelength λ3. The first light beam, the second light beam, and the third light beam can be transmitted through or reflected from the body tissue <NUM> of the subject. Examples of the semiconductor light emitter include a light emitting diode (LED), a laser diode, and an organic electroluminescence (EL) element. The first wavelength λ1 and the second wavelength λ2 are, for example, <NUM> or <NUM>. Therefore, the first light beam and the second light beam are a red light beam. On the other hand, the third wavelength λ3 is, for example, <NUM> or <NUM>. Therefore, the third light beam is an infrared light beam.

When the probe <NUM> is connected to the pulse oximeter <NUM>, electricity from the pulse oximeter <NUM> flows through the first light emitter <NUM>. At this time, the pulse oximeter <NUM> transmits current information (an electric signal) indicating a current value of the electricity to the first light emitter <NUM>. The first light emitter <NUM> is configured to generate voltage information (a voltage signal) indicating a voltage value of first light emitter <NUM> based on the current information. Specifically, the first light emitter <NUM> generates voltage information of the first light emitter <NUM> based on a voltage generated when a photoelectric conversion element (not illustrated) of the first light emitter <NUM> converts electric energy into light energy. The second light emitter <NUM> and the third light emitter <NUM> are also configured to respectively generate voltage information indicating voltage values of the second light emitter <NUM> and the third light emitter <NUM> based on the current information according to the same principle as that of the first light emitter <NUM>. The generated voltage information of each light emitter is transmitted from each light emitter of the probe <NUM> to the acquiring section 11a of the pulse oximeter <NUM>.

The detector <NUM> is an optical sensor having sensitivity to the first wavelength λ1, the second wavelength λ2, and the third wavelength λ3. Examples of the optical sensor include a photodiode, a phototransistor, and a photoresistor.

The detector <NUM> is configured to detect light transmitted through or reflected from the body tissue <NUM> of the subject and output a signal corresponding to an intensity of the detected light beam (an example of physiological information). In the present embodiment, the detector <NUM> detects the first light beam, the second light beam, and the third light beam transmitted through or reflected from the body tissue <NUM> of the subject. In the present embodiment, a signal corresponding to an intensity I1 of the first light beam is referred to as a first signal S1, a signal corresponding to an intensity I2 of the second light beam is referred to as a second signal S2, and a signal corresponding to an intensity I3 of the third light beam is referred to as a third signal S3.

Next, the acquiring section 11a of the pulse oximeter <NUM> will be described. The acquiring section 11a corresponds to an input interface in the input/output interface <NUM>. The acquiring section 11a is configured to acquire, from the detector <NUM>, a plurality of signals (the first signal S1, the second signal S2, and the third signal S3) corresponding to the intensities of the light beams (the intensity I1 of the first light beam, the intensity I2 of the second light beam, and the intensity I3 of the third light beam) acquired using the plurality of light emitters (the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>) of the probe <NUM>. The acquired first signal S1, second signal S2, and third signal S3 are transmitted to the controller <NUM>. The acquiring section 11a transmits the voltage information of each light emitter, which is received from each of the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>, to the failure sensing section <NUM>.

The failure sensing section <NUM> includes at least one processor. The failure sensing section <NUM> is configured to detect a failure of the plurality of light emitters (the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>). The failure sensing section <NUM> senses a failure of each light emitter based on the voltage information of each light emitter received from the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>. Specifically, the failure sensing section <NUM> detects a failure of each light emitter based on information (correlation information) indicating a correspondence relationship between a current signal and a voltage signal, which is determined in advance according to distribution of raw materials of each light emitter, and voltage information of each light emitter received from each light emitter. In the present embodiment, it is assumed that a failure occurs in the light emitter when the function of the light emitter cannot be exerted due to a fault of the photoelectric conversion element, a failure of a wiring board, disconnection of an electric cable connecting the pulse oximeter <NUM> and each light emitter, or the like. Therefore, the failure sensing section <NUM> senses a failure of the first light emitter <NUM> in a case where a voltage value of the first light emitter <NUM> is lower than an assumed value (assumed range) based on the correlation information, for example, in a case where the first light emitter <NUM> cannot convert electric energy into light energy. The failure sensing section <NUM> senses a failure of the first light emitter <NUM> in a case where a voltage value of the first light emitter <NUM> exceeds an assumed value (assumed range) based on the correlation information, for example, in a case where the first light emitter <NUM> cannot receive the current information from the pulse oximeter <NUM>. In the present embodiment, the failure sensing section <NUM> can detect not only such a failure but also a failure or the like caused by a sensor deviating from a predetermined position. The failure sensing section <NUM> transmits a failure sensing result indicating a failure occurrence state of each light emitter to the controller <NUM>.

The controller <NUM> includes a memory <NUM> and at least one processor <NUM> as a hardware configuration. The memory <NUM> includes, for example, a read only memory (ROM) in which various programs and the like are stored, and a random access memory (RAM) having a plurality of work areas in which various programs and the like executed by the processor <NUM> are stored. The processor <NUM> is, for example, a central processing unit (CPU), and is configured to expand a program designated from various programs incorporated in the ROM on the RAM and execute various processing in cooperation with the RAM. The processor <NUM> includes a calculation section 132a. The processor <NUM> implements the processing of the calculation section 132a by, for example, executing a program in cooperation with the RAM.

Here, the program can be stored using various types of non-transitory computer-readable media and supplied to a computer. The non-transitory computer-readable medium includes various types of tangible storage media. Examples of the non-transitory computer-readable medium include a magnetic recording medium (for example, a flexible disk, a magnetic tape, or a hard disk drive), a photomagnetic recording medium (for example, a magneto-optical disk), a CD-ROM (read only memory), a CD-R, a CD-R/W, and a semiconductor memory (for example, a mask ROM, a programmable ROM (PROM), an erasable PROM (EPROM), or a flash ROM).

The calculation section 132a is configured to calculate SpO<NUM> based on a main algorithm (an example of a first algorithm) or a sub-algorithm (an example of a second algorithm) recorded in the memory <NUM>. The main algorithm is an algorithm used when a failure does not occur in a light emitter for acquiring a signal used for the main algorithm. The sub-algorithm is an algorithm used when a failure occurs in the light emitter for acquiring a signal used for the main algorithm. In order to calculate SpO<NUM>, a signal corresponding to at least one red light beam and a signal corresponding to at least one infrared light beam are necessary. Therefore, for example, when a failure occurs in the third light emitter <NUM>, SpO<NUM> is not calculated. That is, in the present embodiment, the sub-algorithm is used when a failure occurs only in the light emitter for acquiring the signal used for the main algorithm among the first light emitter <NUM> and the second light emitter <NUM>.

When no failure occurs in any of the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>, the calculation section 132a calculates SpO<NUM> based on, for example, the first signal S1, the third signal S3, and the main algorithm. Specifically, first, the calculation section 132a calculates an attenuation variation (hereinafter, referred to as a first variation) ΔA<NUM> of the first light beam and an attenuation variation (hereinafter, referred to as a third variation) ΔA<NUM> of the third light beam based on the following expression (<NUM>) or (<NUM>). <MAT> <MAT> Note that I1 indicates the intensity of the first light beam, ΔI<NUM> indicates the variation of the intensity I<NUM> of the first light beam due to the pulsation of the blood of the subject, I<NUM> indicates the intensity of the third light beam, and ΔI<NUM> indicates the variation of the intensity I<NUM> of the third light beam due to the pulsation of the blood of the subject.

When the first variation ΔA<NUM> and the third variation ΔA<NUM> are calculated, the calculation section 132a calculates a value S (decimal notation) of the SpO<NUM> based on the first variation ΔA<NUM> and the third variation ΔA<NUM>. Specific calculation contents will be described below.

The first variation ΔA<NUM> and the third variation ΔA<NUM> can be expressed by the following expression (<NUM>) and (<NUM>). <MAT> <MAT> Here, E indicates an extinction coefficient (dl g-<NUM>cm-<NUM>). Hb indicates the hemoglobin concentration in blood (g dl-<NUM>). Σ indicates the light attenuation rate (cm-<NUM>). ΔD indicates a change in thickness (cm) due to pulsation of blood. The subscript b indicates blood. The subscript t indicates tissue other than blood. The subscript <NUM> indicates the first light beam. The subscript <NUM> indicates the third light beam.

Expressions (<NUM>) and (<NUM>) can be modified as follows. <MAT> <MAT> Here, Ex is a variable obtained by replacing (Σt ΔDt)/(Hb ΔDb). The subscript <NUM> indicates the first light beam. The subscript <NUM> indicates the third light beam.

Expressions (<NUM>) and (<NUM>) can be modified as follows. <MAT> <MAT>.

With respect to Expression (<NUM>), the extinction coefficient Eb1 of the blood of the first light beam can be approximated by the extinction coefficient Eb3 of the blood of the third light beam as follows. <MAT> Here, a and b are constants. The subscript <NUM> indicates the first light beam. The subscript <NUM> indicates the third light beam.

Ex1 of the first light beam can be approximated by Ex3 of the third light beam as follows. <MAT> Here, α and β are constants. The subscript <NUM> indicates the first light beam. The subscript <NUM> indicates the third light beam.

When Expression (<NUM>) and Expression (<NUM>) are rewritten using Expression (<NUM>) and Expression (<NUM>), the following Expression (<NUM>) and Expression (<NUM>) are obtained. <MAT> <MAT> <MAT> <MAT>.

When a statistically obtained constant value is used as Ex3, the values of Eb3 and Hb ΔDb, which are variables, are obtained by calculating the following determinant (<NUM>).

When SpO<NUM>, which is expressed in percentage, is converted into S, which is expressed in decimal, the extinction coefficient Eb3 of the third light beam is expressed by the following expression (<NUM>). <MAT> Here, Eo indicates an extinction coefficient of oxyhemoglobin. Er indicates an extinction coefficient of deoxyhemoglobin. The subscript <NUM> indicates the third light beam. Therefore, the calculation section 132a calculates a value S of the SpO<NUM> by the following expression (<NUM>).

On the other hand, for example, when the failure sensing section <NUM> detects a failure in the first light emitter <NUM>, the calculation section 132a calculates a value S of SpO<NUM>, which is expressed in decimal, based on the second signal S2, the third signal S3, and the sub-algorithm. Specifically, first, the calculation section 132a calculates a variation in light attenuation of the second light beam (hereinafter, referred to as a second variation) ΔA<NUM> and the third variation ΔA<NUM> based on the following expression (<NUM>) or the above expression (<NUM>). <MAT> Note that I<NUM> indicates the intensity of the second light beam, and ΔI<NUM> indicates the variation of the intensity I<NUM> of the second light beam due to the pulsation of the blood of the subject.

When the second variation ΔA<NUM> and the third variation ΔA<NUM> are calculated, the calculation section 132a calculates the value S (decimal notation) of the SpO<NUM> based on the second variation ΔA<NUM> and the third variation ΔA<NUM>. Specific calculation contents will be described below. In the description of the contents of the calculation, the description of parts overlapping with the example in which the SpO<NUM> is calculated based on the first signal S1, the third signal S3, and the main algorithm will be appropriately omitted.

The second variation ΔA<NUM> can be expressed by the following expression (<NUM>). <MAT> Here, the subscript <NUM> indicates the second light beam.

Expression (<NUM>) can be modified as follows. <MAT> Here, Ex is a variable obtained by replacing (Σt ΔDt)/(Hb ΔDb). The subscript <NUM> indicates the second light beam.

Expression (<NUM>) can be modified as follows.

With respect to Expression (<NUM>), the extinction coefficient Eb2 of the blood of the second light beam can be approximated by the extinction coefficient Eb3 of the blood of the third light beam as follows. <MAT> Here, a and b are constants. The subscript <NUM> indicates the second light beam. The subscript <NUM> indicates the third light beam.

Ex2 of the second light beam can be approximated by Ex3 of the third light beam as follows. <MAT> Here, α and β are constants. The subscript <NUM> indicates the second light beam. The subscript <NUM> indicates the third light beam.

When Expression (<NUM>) is rewritten using Expression (<NUM>) and Expression (<NUM>), the following Expression (<NUM>) is obtained. <MAT> <MAT>.

When SpO<NUM>, which is expressed in percentage, is converted into S, which is expressed in decimal, the extinction coefficient Eb3 of the third light beam is expressed by the above expression (<NUM>). Therefore, the calculation section 132a calculates the value S of the SpO<NUM> by the above expression (<NUM>).

The controller <NUM> is configured to determine the presence or absence of a failure in each light emitter based on the failure sensing result received from the failure sensing section <NUM>. Based on the determination, the controller <NUM> determines an algorithm used by the calculation section 132a to calculate SpO<NUM>. The controller <NUM> causes the calculation section 132a to calculate SpO<NUM> based on the determination. Therefore, the algorithm used for the calculation of SpO<NUM> is appropriately selected according to the state of each light emitter. For example, in a case where the signals used for the main algorithm are the first signal S1 and the third signal S3, the controller <NUM> controls the calculation section 132a to calculate SpO<NUM> based on the main algorithm when the failure sensing section <NUM> senses no failure in any of the light emitters or senses a failure only in the second light emitter <NUM>. On the other hand, when the failure sensing section <NUM> has sensed a failure in the first light emitter <NUM>, the controller <NUM> controls the calculation section 132a to calculate SpO<NUM> based on the sub-algorithm. In other cases, the controller <NUM> does not cause the calculation section 132a to calculate SpO<NUM>.

When the calculation section 132a calculates the SpO<NUM>, the controller <NUM> generates a display signal for displaying the SpO<NUM> on the display <NUM>, and transmits the display signal to the display <NUM>.

The controller <NUM> generates a failure signal when the failure sensing section <NUM> detects that a failure has occurred in at least one of the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>. The generated failure signal is transmitted to the notifying section <NUM>.

The display <NUM> includes, for example, a liquid crystal display (LCD). The display <NUM> displays predetermined information based on a display signal received from the controller <NUM>. Examples of the predetermined information include SpO<NUM>, pulse rate, remaining battery level, and date and time.

The notifying section <NUM> is configured to notify that a failure has occurred in at least one of the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM> based on the failure signal received from the controller <NUM>. The notification of the notifying section <NUM> may be performed by at least one of visual notification, auditory notification, and tactile notification. Through the notification of the notifying section <NUM>, a medical worker can recognize that a failure has occurred in at least one light emitter, and the calculation of SpO<NUM> has been performed based on the sub-algorithm. The mode of notification that a failure has occurred in the first light emitter <NUM> or the second light emitter <NUM> may be different from the mode of notification that a failure has occurred in the first light emitter <NUM> and the second light emitter <NUM>, or the third light emitter <NUM>. In this case, the medical worker can easily determine whether the calculation of SpO<NUM> is executed.

Next, the processing contents executed by the controller <NUM> in the first embodiment will be described in detail with reference to <FIG> is a flowchart of a processing content executed by the controller <NUM> in the first embodiment. In the present embodiment, it is assumed that the first wavelength λ1 is <NUM> and the second wavelength λ2 is <NUM>.

A red light beam having a wavelength of <NUM> is generally used mainly for the measurement of SpO<NUM>, whereas a red light beam having a wavelength of <NUM> is used mainly for the measurement of the carbon monoxide concentration. This is because SpO<NUM> can be measured more accurately when SpO<NUM> is measured using the red light beam having a wavelength of <NUM> than the case of measuring SpO<NUM> using the red light beam having a wavelength of <NUM>. Therefore, in the present embodiment, the signals used for the main algorithm are the first signal S1 and the third signal S3. That is, in the present embodiment, the light emitters used for the main algorithm are the first light emitter <NUM> and the third light emitter <NUM>, and the light emitters used for the sub-algorithm are the second light emitter <NUM> and the third light emitter <NUM>.

As illustrated in <FIG>, in STEP <NUM>, the acquiring section 11a acquires a plurality of signals (a first signal S1, a second signal S2, and a third signal S3) from the detector <NUM>. The acquired first signal S1, second signal S2, and third signal S3 are transmitted to the controller <NUM>.

In STEP <NUM>, the acquiring section 11a acquires, from each of the light emitters, voltage information generated based on the current information transmitted from the pulse oximeter <NUM> to the plurality of light emitters (the first light emitter <NUM>, second light emitter <NUM>, and third light emitter <NUM>). The acquired voltage information is transmitted to the failure sensing section <NUM>. The failure sensing section <NUM> senses a failure of the plurality of light emitters based on the acquired voltage information, and transmits a failure sensing result to the controller <NUM>.

In STEP <NUM>, the controller <NUM> determines whether there is a failure in the light emitters used for the main algorithm, that is, the first light emitter <NUM> and the third light emitter <NUM>, based on the failure sensing result received from the failure sensing section <NUM>. In a case where the controller <NUM> determines that no failure has occurred in the first light emitter <NUM> and the third light emitter <NUM> (NO in STEP <NUM>), the calculation section 132a calculates the SpO<NUM> based on the first signal S1, the third signal S3, and the main algorithm (STEP <NUM>). On the other hand, in a case where the controller <NUM> determines that a failure has occurred in at least one of the first light emitter <NUM> and the third light emitter <NUM> (YES in STEP <NUM>), the processing proceeds to STEP <NUM>.

In STEP <NUM>, the controller <NUM> determines whether there is a failure in the light emitters used for the sub-algorithm, that is, the second light emitter <NUM> and the third light emitter <NUM>, based on the failure sensing result received from the failure sensing section <NUM>. In a case where the controller <NUM> determines that no failure has occurred in the second light emitter <NUM> and the third light emitter <NUM> (NO in STEP <NUM>), the calculation section 132a calculates SpO<NUM> based on the second signal S2, the third signal S3, and the sub-algorithm (STEP <NUM>). On the other hand, in a case where the controller <NUM> determines that a failure has occurred in at least one of the second light emitter <NUM> and the third light emitter <NUM> (YES in STEP <NUM>), the controller <NUM> ends the present processing without causing the calculation section 132a to perform the calculation of SpO<NUM>.

In the pulse oximeter according to the related art, when a failure occurs in any emitters of the probe, the arterial oxygen saturation may not be calculated. Therefore, when a failure occurs in any emitters, there is a possibility that the medical worker cannot measure the arterial oxygen saturation using the pulse oximeter until the failure is resolved. For example, in a case where the arterial oxygen saturation of a subject is <NUM>% or less, the subject may be in a respiratory failure state, so that immediate action is required. Therefore, it is desirable that a state in which the pulse oximeter cannot calculate the arterial oxygen saturation is not generated so that the medical worker can immediately notice the change in the condition of the subject. In view of such circumstances, there is a demand for a pulse oximeter capable of continuously calculating the arterial oxygen saturation even when a failure occurs in any emitters of a probe, that is, having failure resistance against the failure of the light emitter of the probe.

According to the pulse oximeter <NUM> of the present embodiment, when no failure occurs in the first light emitter <NUM> and the third light emitter <NUM>, the calculation section 132a calculates SpO<NUM> based on the main algorithm. On the other hand, for example, in a case where a failure has occurred in the first light emitter <NUM>, the calculation section 132a calculates SpO<NUM> based on the sub-algorithm. Specifically, in a case where a failure has occurred in the first light emitter <NUM>, the calculation section 132a calculates SpO<NUM> based on the second signal S2, the third signal S3, and the sub-algorithm. As described above, even if a failure has occurred in any emitters of the probe <NUM>, the calculation section 132a can calculate the SpO<NUM>. Therefore, the pulse oximeter <NUM> has a failure resistance against a failure of the light emitter of the probe <NUM>.

In the pulse oximeter <NUM> according to the present embodiment, the failure sensing section <NUM> can sense a failure of a plurality of light emitters (the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>) based on voltage information indicating voltage values of the plurality of light emitters. Specifically, the failure sensing section <NUM> can sense the failure of the plurality of light emitters by comparing an assumed value based on the current information and the correlation information transmitted from the pulse oximeter <NUM> to the plurality of light emitters with the voltage information received from the plurality of light emitters. As described above, the pulse oximeter <NUM> can sense a failure of each light emitter with a relatively simple configuration.

Next, the processing content executed by the controller <NUM> in the second embodiment will be described in detail with reference to <FIG> and <FIG>. In the description of the second embodiment, the description of the same parts as those of the first embodiment will be omitted. The second embodiment is different from the first embodiment in that the probe <NUM> further includes a fourth light emitter <NUM> as indicated by a broken line in <FIG>. In the present embodiment, it is assumed that the third wavelength λ3 is <NUM>. Further, also in the present embodiment, it is assumed that the light emitters used for the main algorithm are the first light emitter <NUM> and the third light emitter <NUM>.

In the present embodiment, the sub-algorithm includes a first sub-algorithm, a second sub-algorithm, and a third sub-algorithm. The light emitters used for the first sub-algorithm are the first light emitter <NUM> and the fourth light emitter <NUM>. The light emitters used for the second sub-algorithm are the second light emitter <NUM> and the third light emitter <NUM>. The light emitters used for the third sub-algorithm are the second light emitter <NUM> and the fourth light emitter <NUM>.

The fourth light emitter <NUM> is, for example, a semiconductor light emitter capable of emitting a fourth light beam having a fourth wavelength λ4. Examples of the semiconductor light emitter include a light emitting diode (LED), a laser diode, and an organic electroluminescence (EL) element. The fourth wavelength λ4 is, for example, <NUM>. Therefore, the fourth light beam is an infrared light beam.

The fourth light emitter <NUM> is configured to generate voltage information based on the current information transmitted from the pulse oximeter <NUM>, which is the same as the other light emitters (the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>). The generated voltage information is transmitted to the acquiring section 11a of the pulse oximeter <NUM>.

In the present embodiment, the detector <NUM> also has sensitivity to the fourth wavelength λ4. The detector <NUM> is also configured to receive the fourth light beam transmitted through or reflected from the body tissue <NUM> of the subject and output a signal (fourth signal S4) corresponding to an intensity I4 (an example of physiological information) of the received fourth light beam.

Next, the processing contents executed by the controller <NUM> in the second embodiment will be described in detail with reference to <FIG> is a flowchart of a processing content executed by the controller <NUM> in the second embodiment.

STEPs <NUM> to <NUM> are the same as STEPs <NUM> to <NUM> in <FIG>. In this case, the acquiring section 11a also acquires the fourth signal S4 from the detector <NUM> (STEP <NUM>). In addition, the acquiring section 11a acquires, from the fourth light emitter <NUM>, voltage information of the fourth light emitter <NUM> generated based on the current information transmitted from the pulse oximeter <NUM> to the fourth light emitter <NUM> (STEP <NUM>). At this time, the failure sensing section <NUM> also detects a failure of the fourth light emitter <NUM> based on the voltage information of the fourth light emitter <NUM> acquired by the acquiring section 11a, and transmits a failure sensing result to controller <NUM>.

In a case where the controller <NUM> determines that a failure has occurred in at least one of the first light emitter <NUM> and the third light emitter <NUM> in STEP <NUM> (YES in STEP <NUM>), the processing proceeds to STEP <NUM>. In STEP <NUM>, the controller <NUM> determines whether there is a failure in the light emitters used for the first sub-algorithm, that is, the first light emitter <NUM> and the fourth light emitter <NUM>, based on the failure sensing result received from the failure sensing section <NUM>. In a case where the controller <NUM> determines that no failure has occurred in the first light emitter <NUM> and the fourth light emitter <NUM> (NO in STEP <NUM>), the calculation section 132a calculates SpO<NUM> based on the first signal S1, the fourth signal S4, and the first sub-algorithm (STEP <NUM>). On the other hand, in a case where the controller <NUM> determines that there is a failure in at least one of the first light emitter <NUM> and the fourth light emitter <NUM> (YES in STEP <NUM>), the processing proceeds to STEP <NUM>.

In STEP <NUM>, the controller <NUM> determines whether there is a failure in the light emitters used for the second sub-algorithm, that is, the second light emitter <NUM> and the third light emitter <NUM>, based on the failure sensing result received from the failure sensing section <NUM>. In a case where the controller <NUM> determines that no failure has occurred in the second light emitter <NUM> and the third light emitter <NUM> (NO in STEP <NUM>), the calculation section 132a calculates SpO<NUM> based on the second signal S2, the third signal S3, and the second sub-algorithm (STEP <NUM>). On the other hand, in a case where the controller <NUM> determines that there is a failure in at least one of the second light emitter <NUM> and the third light emitter <NUM> (YES in STEP <NUM>), the processing proceeds to STEP <NUM>.

In STEP <NUM>, the controller <NUM> determines whether there is a failure in the light emitters used for the third sub-algorithm, that is, the second light emitter <NUM> and the fourth light emitter <NUM>, based on the failure sensing result received from the failure sensing section <NUM>. In a case where the controller <NUM> determines that no failure has occurred in the second light emitter <NUM> and the fourth light emitter <NUM> (NO in STEP <NUM>), the calculation section 132a calculates SpO<NUM> based on the second signal S2, the fourth signal S4, and the third sub-algorithm (STEP <NUM>). On the other hand, in a case where the controller <NUM> determines that there is a failure in at least one of the second light emitter <NUM> and the fourth light emitter <NUM> (YES in STEP <NUM>), the controller <NUM> ends the present processing without causing the calculation section 132a to perform the calculation of SpO<NUM>.

According to the pulse oximeter <NUM> of the present embodiment, for example, in a case where a failure occurs only in the third light emitter <NUM>, the controller <NUM> determines to use the first sub-algorithm, and controls the calculation section 132a to calculate SpO<NUM> using the first sub-algorithm. Therefore, in the present embodiment, even if a failure occurs in the third light emitter <NUM>, the calculation section 132a of the pulse oximeter <NUM> can calculate SpO<NUM>, so that the failure resistance against the failure of the plurality of light emitters of the probe <NUM> is further improved.

Next, a physiological parameter calculation system <NUM> according to a third embodiment will be described with reference to <FIG>. In the description of the third embodiment, the description of the same parts as those of the first embodiment will be omitted. <FIG> is a diagram illustrating a functional configuration of the physiological parameter calculation system <NUM> according to the present embodiment.

As illustrated in <FIG>, the physiological parameter calculation system <NUM> includes an electrocardiogram examination device <NUM> (an example of a physiological parameter calculation device) and an electrode group <NUM> (an example of a sensor).

The electrocardiogram examination device <NUM> is a device for calculating electrocardiogram data (an example of a physiological parameter) of a subject using a standard <NUM>-lead electrocardiogram. As illustrated in <FIG>, the electrocardiogram examination device <NUM> includes an input/output interface <NUM>, a failure sensing section <NUM>, a controller <NUM>, a display <NUM>, and a notifying section <NUM>. These components are connected to each other via a bus <NUM> so as to be able to communicate with each other. The electrocardiogram examination device <NUM> also includes a power supply, a digital/analog circuit, and the like (not illustrated).

The input/output interface <NUM> may have the same configuration as the input/output interface <NUM>, and includes an acquiring section 211a. The electrocardiogram examination device <NUM> can be connected to the electrode group <NUM> via the input/output interface <NUM> in a wired or wireless manner.

Here, the electrode group <NUM> will be described. The electrode group <NUM> includes a plurality of electrodes (for example, <NUM> electrodes) including a first electrode 220A, a second electrode 220B, and a third electrode 220C. Each electrode is attached to body tissue <NUM> (such as extremities or chest) of a subject. Each electrode comes into contact with a measurement part of the subject and functions as a sensor for deriving a potential change of the measurement part. Each electrode is configured to derive a potential difference of a measurement part. In addition, the electrocardiogram examination device <NUM> also includes an indifferent electrode (not illustrated), and the indifferent electrode is configured to remove external noise induced in the same phase in the electrode group <NUM>. Further, each electrode includes a detector. For example, the first electrode 220A includes a first detector <NUM>, the second electrode 220B includes a second detector <NUM>, and the third electrode 220C includes a third detector <NUM>.

The first detector <NUM> is configured to detect an electrocardiogram signal (a first signal S11) corresponding to an electromotive force (an example of physiological information) transmitted from an attachment gel included in the first electrode 220A, and to transmit the first signal S11 to the acquiring section 211a via a lead wire.

Since the detectors other than the first detector <NUM> (for example, the second detector <NUM> and the third detector <NUM>) have the same configuration as the first detector <NUM>, the description thereof will be omitted. Each of the electrodes including the other detectors is attached to a part of the body tissue <NUM> that is different from a part to which the first electrode 220A including the first detector <NUM> is attached. In the present embodiment, an electrocardiogram signal corresponding to an electromotive force acquired by using the second detector <NUM> is referred to as a second signal S12, and an electrocardiogram signal corresponding to an electromotive force acquired by using the third detector <NUM> is referred to as a third signal S13.

Each detector is configured to generate voltage information indicating a voltage value of each detector by the same principle as in the first embodiment. The generated voltage information related to each detector is transmitted from each detector to the acquiring section 211a of the electrocardiogram examination device <NUM>.

Next, the acquiring section 211a of the electrocardiogram examination device <NUM> will be described. The acquiring section 211a is configured to acquire, from the electrode group <NUM>, a plurality of electrocardiogram signals corresponding to electromotive forces acquired using a plurality of detectors of the electrode group <NUM>. The plurality of acquired electrocardiogram signals (the first signal S11, the second signal S12, and the third signal S13) are transmitted to the controller <NUM>. In addition, the acquiring section 211a transmits the voltage information received from each detector to the failure sensing section <NUM>.

The failure sensing section <NUM> has the same configuration as that of the failure sensing section <NUM> in the first embodiment, and thus the description thereof will be omitted. In the present embodiment, it is assumed that a failure occurs in the detector when the function of the detector cannot be exerted due to a fault of a photoelectric conversion element, disconnection of an electric cable connecting the electrocardiogram examination device <NUM> and each detector, electrode detachment, or the like.

The controller <NUM> includes one or more memory <NUM> and one or more processor <NUM> as a hardware configuration. Since the memory <NUM> and the processor <NUM> have the same configurations as those of the memory <NUM> and the processor <NUM> in the first embodiment, the description thereof will be omitted. The processor <NUM> includes a calculation section 2132a.

The calculation section 2132a is configured to calculate electrocardiogram data based on a main algorithm (an example of a first algorithm) or a sub-algorithm (an example of a second algorithm) recorded in the memory <NUM>. The main algorithm is an algorithm used when a failure does not occur in a detector for acquiring a signal used for the main algorithm. The sub-algorithm is an algorithm used when a failure has occurred in a detector for acquiring a signal used for the main algorithm. When electrocardiogram data is calculated using the standard <NUM>-lead method, ten electrodes are used, four of which are attached to the extremities, and the remaining six electrodes are attached to the chest. In the present embodiment, it is assumed that the first electrode 220A and the second electrode 220B are attached adjacent to each other on the chest of the subject, and the third electrode 220C is attached to the left leg of the subject. Therefore, in the present embodiment, the electrocardiogram data can be calculated even when a failure occurs in the first electrode 220A or the second electrode 220B, but the electrocardiogram data is not calculated when a failure occurs in the third detector <NUM>.

When no failure occurs in any of the first detector <NUM>, the second detector <NUM>, and the third detector <NUM>, the calculation section 2132a calculates electrocardiogram data based on, for example, the first signal S11, the second signal S12, the third signal S13, and the main algorithm. Specifically, when a potential difference between predetermined two electrodes is induced, the calculation section 2132a integrates potential changes of the respective inductions and calculates electrocardiogram data.

On the other hand, for example, when a failure occurs in the first detector <NUM>, and the electrocardiogram data can be calculated by using the second detector <NUM> instead of the first detector <NUM>, the calculation section 2132a calculates the electrocardiogram data based on the second signal S22, the third signal S23, and the sub-algorithm.

Based on the same principle as in the first embodiment, the controller <NUM> determines the presence or absence of a failure in each detector, and determines an algorithm used by the calculation section 2132a to calculate electrocardiogram data. The controller <NUM> causes the calculation section 2132a to calculate the electrocardiogram data based on the determination.

The controller <NUM> generates a display signal for displaying the electrocardiogram data on the display <NUM> and transmits the display signal to the display <NUM> according to the same principle as in the first embodiment.

The controller <NUM> generates a failure signal when the failure sensing section <NUM> senses that a failure has occurred in at least one of the first detector <NUM>, the second detector <NUM>, and the third detector <NUM>. The generated failure signal is transmitted to the notifying section <NUM>.

The display <NUM> may have the same configuration as the display <NUM> in the first embodiment.

The notifying section <NUM> is configured to notify that a failure has occurred in at least one of the first detector <NUM>, the second detector <NUM>, and the third detector <NUM> based on the failure signal received from the controller <NUM>. The notification of the notifying section <NUM> is the same as the notification of the notifying section <NUM> according to the first embodiment, and thus the description thereof will be omitted.

Next, the processing contents executed by the controller <NUM> in the third embodiment will be described in detail with reference to <FIG>. In the present embodiment, it is assumed that the main algorithm is used when a failure has not occurred in any of the detectors, and the sub-algorithm is used when a failure has occurred in only one of the first detector <NUM> and the second detector <NUM>. In the present embodiment, it is assumed that no failure occurs in the detectors of the electrodes other than the first electrode 220A, the second electrode 220B, and the third electrode 220C.

The controller <NUM> executes STEP <NUM> to STEP <NUM> in <FIG>. When no failure occurs in any of the detectors (NO in STEP <NUM>), the calculation section 2132a calculates electrocardiogram data based on the first signal S11, the second signal S12, the third signal S13, and the main algorithm (STEP <NUM>). On the other hand, in a case where the controller <NUM> determines that a failure has occurred in any of the detectors (YES in STEP <NUM>), the processing proceeds to STEP <NUM>.

In STEP <NUM>, the controller <NUM> determines whether there is a failure in the first detector <NUM> and the second detector <NUM>, or the third detector <NUM>. In a case where the controller <NUM> determines that no failure has occurred in the first detector <NUM> and the second detector <NUM>, or the third detector <NUM> (NO in STEP <NUM>), the calculation section 2132a calculates electrocardiogram data based on the first signal S11 or the second signal S12, or the third signal S13, and the sub-algorithm (STEP <NUM>). On the other hand, in a case where the controller <NUM> determines that a failure has occurred in the first detector <NUM> and the second detector <NUM>, or the third detector <NUM> (YES in STEP <NUM>), the controller <NUM> ends the present processing without causing the calculation section 2132a to perform the calculation of the electrocardiogram data.

According to the electrocardiogram examination device <NUM> of the present embodiment, when no failure occurs in any of the detectors, the calculation section 2132a calculates electrocardiogram data based on the main algorithm. On the other hand, for example, when a failure has occurred in the first detector <NUM>, the calculation section 2132a calculates electrocardiogram data based on the sub-algorithm. As described above, even if a failure has occurred in any detectors, the calculator section 2132a can calculate electrocardiogram data. Therefore, the electrocardiogram examination device <NUM> has failure resistance against a failure of the detector.

The above embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified and improved without departing from the gist thereof.

In the first embodiment, the first light beam and the second light beam are a red light beam, and the third light beam is an infrared light beam. For example, the second light beam may be a red light beam, and the first light beam and the third light beam may be an infrared light beam.

The first wavelength λ1 is <NUM> and the second wavelength λ2 is <NUM> in the first embodiment and the second embodiment, but the first wavelength λ1 may be <NUM> and the second wavelength λ2 may be <NUM>.

In the second embodiment, the first light beam and the second light beam are a red light beam, and the third light beam and the fourth light beam are an infrared light beam, and the present invention is not limited to this example. For example, the first light beam and the second light beam may be an infrared light beam, and the third light beam and the fourth light beam may be a red light beam.

The third wavelength λ3 is <NUM> and the fourth wavelength λ4 is <NUM> in the second embodiment, but the third wavelength λ3 may be <NUM>, and the fourth wavelength λ4 may be <NUM>.

The calculation section 132a calculates SpO<NUM> in decimal notation in the first embodiment and the second embodiment, but may calculate SpO<NUM> in percentage notation.

In the first embodiment and the second embodiment, a signal that is not used for the calculation of SpO<NUM> may be used for the calculation of a physiological parameter other than SpO<NUM>. For example, in the first embodiment, when no failure occurs in any of the light emitters, the first signal S1 and the third signal S3 may be used for the calculation of the SpO<NUM>, and the second signal S2 may be used for the calculation of the value of the carbon monoxide concentration.

In the above-described embodiments, the physiological parameter calculation device (the pulse oximeter <NUM> and the electrocardiogram examination device <NUM>) includes the display and the notifying section, but may not include the display and the notifying section. In this case, the physiological parameter calculation device may be connected to an external device (for example, a bedside monitor) including a display and a notifying section in a wired or wireless manner.

In the above-described embodiments, the failure sensing sections <NUM>, <NUM> senses the failure of each element based on the voltage information, but may detect the failure of each element based on the current information. In this case, the physiological parameter calculation device converts a current signal into a voltage signal to generate voltage information, and transmits the voltage information to each element. Each element transmits current information, which is generated based on a current generated when electric energy is converted into light energy, to the acquiring sections 11a, 211a of the physiological parameter calculation device. The failure sensing sections <NUM>, <NUM> sense a failure of each element based on the received current information and correlation information.

In the above-described embodiments, the controllers <NUM>, <NUM> generate a failure signal when the failure sensing section <NUM> senses that a failure has occurred in at least one of the first light emitter <NUM>, the second light emitter <NUM>, and the third light emitter <NUM>, or when the failure sensing section <NUM> senses that a failure has occurred in at least one of the first detector <NUM>, the second detector <NUM>, and the third detector <NUM>, but the present invention are not limited to this example. For example, the controller <NUM> may be configured to generate the failure signal only when the physiological parameter cannot be calculated. In this case, the medical worker can recognize, through the notification of the notifying section <NUM>, that the physiological parameter calculation device is in a state in which the physiological parameter cannot be calculated.

In the above-described embodiments, the functions of the failure sensing sections <NUM>, <NUM> may be implemented by the processors <NUM>, <NUM> of the controllers <NUM>, <NUM>.

STEP <NUM> is executed after STEP <NUM> in the first embodiment and the third embodiment, but may be executed simultaneously with STEP <NUM> or before STEP <NUM>.

Claim 1:
A physiological parameter calculation device comprising:
an acquiring section (11a) configured to acquire a plurality of signals corresponding to physiological information of a subject acquired using a plurality of elements (<NUM>, <NUM>, <NUM>, <NUM>) of a sensor (<NUM>);
a failure sensing section (<NUM>) configured to sense a failure of the plurality of elements (<NUM>, <NUM>, <NUM>, <NUM>); and
a calculation section (132a) configured to calculate a physiological parameter based on the plurality of signals acquired by the acquiring section (11a), and a first algorithm or a second algorithm,
wherein the calculation section (132a) is configured to calculate the physiological parameter based on the first algorithm when the failure sensing section (<NUM>) does not sense a failure in an element for acquiring a signal used for the first algorithm among the plurality of elements (<NUM>, <NUM>, <NUM>, <NUM>), and the calculation section (132a) is configured to calculate the physiological parameter based on the second algorithm when the failure sensing section (132a) senses that a failure occurs in an element for acquiring a signal used for the first algorithm among the plurality of elements (<NUM>, <NUM>, <NUM>, <NUM>);
characterised in that the acquiring section (11a) is configured to receive voltage information from each of the plurality of elements (<NUM>, <NUM>, <NUM>, <NUM>), and the acquiring section (11a) is configured to transmit the received voltage information of each element to the failure sensing section (<NUM>), and the failure sensing section is configured to detect the failure of the plurality of elements by comparing an assumed value based on current information and correlation information transmitted to the plurality of elements with the voltage information received from the plurality of elements, said correlation information being defined as information indicating a correspondence relationship between a current signal and a voltage signal, which is determined in advance according to distribution of raw materials of each light emitter, and voltage information of each light emitter received from each light emitter.