Oxygen saturation measuring device and oxygen saturation measuring method

Abstract

To provide an oxygen saturation measuring device allowing a subject to easily and time consecutively measure oxygen saturation and improve conditions of a respiratory system.SOLUTION: An oxygen saturation measuring device 10 includes a band 12 to be wound around a wrist of a subject, a first sensor part 11 attached to the band 12 to acquire a pulse wave signal of an artery of the wrist and measuring oxygen saturation of the artery of the wrist based on the acquired pulse wave signal, and a notification part 26 notifying the subject of a warning representing a possibility of respiratory disorder when the oxygen saturation measured by the first sensor part 11 satisfies a preset condition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to an oxygen saturation measuring device and an oxygen saturation measuring method. [Background technology]

[0002] Conventionally, as a device for measuring arterial blood oxygen saturation (SpO2), a touchscreen interface equipped with a pulse oximeter has been disclosed, as shown in Patent Document 1. Patent Document 1 states that the oxygen saturation in the arterial blood of the fingertip can be measured by having the subject touch the touchscreen with their fingertip. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-246894 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Generally, if oxygen saturation falls outside a predetermined range, it can be inferred that the subject's respiratory condition is poor. For example, if oxygen saturation is within a preset range of approximately 95% to 99%, the subject's respiratory condition can be judged as normal. On the other hand, if oxygen saturation is outside the set range, such as 94%, the subject's respiratory condition can be judged as poor.

[0005] If the oxygen saturation of the subject can be measured continuously over time, the temporal changes in the measured values ​​can be obtained. By using the temporal changes in the measured values, it becomes possible to diagnose the respiratory condition of the subject more comprehensively, and as a result, it is possible to improve the respiratory condition. In order to measure oxygen saturation continuously over time, the oxygen saturation measuring device needs to be attached to a predetermined position on the subject's body continuously over time.

[0006] However, as in Patent Document 1, when the contact area of ​​the person being measured is the fingertip, the oxygen saturation measuring device is continuously attached to the fingertip. This can easily interfere with tasks such as gripping a pen or operating an electronic device with the fingers, as well as daily activities such as eating and excretion. In other words, when measuring oxygen saturation at the fingertip, it is difficult to measure continuously over time.

[0007] This disclosure has been made in view of the above, and provides an oxygen saturation measuring device and an oxygen saturation measuring method that make it easy for a person to measure their oxygen saturation continuously over time and that can improve the condition of their respiratory system. [Means for solving the problem]

[0008] An oxygen saturation measuring device according to a first aspect of this disclosure comprises: a band that is wrapped around the wrist of a person being measured; a first sensor unit attached to the band that acquires a pulse wave signal from the artery in the wrist and measures the oxygen saturation of the artery in the wrist based on the acquired pulse wave signal; and a notification unit that notifies the person being measured of a warning indicating the possibility of respiratory distress when the oxygen saturation measured by the first sensor unit meets a preset condition.

[0009] According to the first embodiment, a band is wrapped around the wrist of the person being measured, and a pulse wave signal from the artery in the wrist is acquired by a first sensor unit attached to the band. The oxygen saturation of the artery in the wrist is then measured based on the acquired pulse wave signal. In other words, since the oxygen saturation is measured at the wrist, it is less likely to interfere with the person's work or daily activities compared to when the oxygen saturation is measured at the fingertips, and the oxygen saturation measuring device can be operated continuously over time.

[0010] Furthermore, if the measured oxygen saturation level of the wrist artery meets pre-set conditions, the subject is notified of a potential respiratory problem. This warning encourages the subject to take action, such as consulting a doctor, which can ultimately lead to an improvement in their respiratory condition.

[0011] In the first embodiment, the first sensor unit may be mounted on the inside of the band.

[0012] With the above configuration, the first sensor unit is attached to the inside of the band, that is, the side of the band that comes into contact with the wrist, making it easier to measure, for example, the radial artery, which is close to the inner surface of the wrist.

[0013] Furthermore, in the first embodiment, if the measured oxygen saturation does not reach a preset standard value, the notification unit may issue a warning prompting the person being measured to measure their oxygen saturation at the fingertip.

[0014] With the above configuration, if the measured oxygen saturation does not reach a preset standard value, the person being measured is notified as a warning to take an oxygen saturation measurement at the fingertip. This allows for more accurate measurement of oxygen saturation.

[0015] In the first embodiment, the device may further include a second sensor unit attached to the band for measuring the oxygen saturation of the artery at the fingertip of the person being measured.

[0016] According to the above configuration, a second sensor unit is further provided, which is attached to the band and measures the oxygen saturation of the arteries in the fingertips. Therefore, both continuous measurement of oxygen saturation over time at the wrist and measurement of oxygen saturation with higher accuracy at the fingertips can be achieved using a single oxygen saturation measuring device. In other words, there is no need to prepare a separate oxygen saturation measuring device for measuring the oxygen saturation of the arteries in the fingertips.

[0017] In the first embodiment, the second sensor unit may be attached to the outside of the band.

[0018] According to the above configuration, the second sensor unit is attached to the outside of the band, that is, the side of the band that does not contact the wrist, and at a position where the subject can easily visually recognize it. Therefore, compared with the case where the second sensor unit is attached to the inside of the band, it is easier for the subject to handle the second sensor unit.

[0019] The oxygen saturation measuring device according to the second aspect of the present disclosure includes a band wound around the wrist of a subject, a first sensor unit attached to the band to acquire a pulse wave signal of the artery of the wrist, and measures the oxygen saturation of the artery of the wrist based on the acquired pulse wave signal, a notification unit that notifies a warning indicating the possibility of respiratory disorder to the subject when the oxygen saturation measured by the first sensor unit satisfies a preset condition, a second sensor unit attached to the band to measure the oxygen saturation of the artery of the fingertip of the subject, and a display unit that displays the oxygen saturation measured by the second sensor unit.

[0020] According to the second aspect, both continuously measuring the oxygen saturation over time at the position of the wrist and measuring the oxygen saturation with higher measurement accuracy at the position of the fingertip can be realized using one oxygen saturation measuring device.

[0021] Also, in the second aspect, the notification unit and the display unit may be integrated.

[0022] According to the above configuration, compared with the case where the notification unit and the display unit are separate bodies, the overall dimensions of the oxygen saturation measuring device are suppressed, so the oxygen saturation measuring device can be configured compactly.

[0023] The oxygen saturation measuring method according to the third aspect of the present disclosure acquires a pulse wave signal of the artery of the wrist of a subject, measures the oxygen saturation of the artery based on the acquired pulse wave signal, and notifies a warning to the subject when the measured oxygen saturation satisfies a preset condition.

[0024] According to the third aspect, similar to the first aspect, it is easy to continuously measure the oxygen saturation measuring device over time, and the state of the respiratory organ can be improved. [Effects of the Invention]

[0025] The oxygen saturation measuring device and oxygen saturation measuring method described herein make it easier for the person being measured to continuously measure their oxygen saturation over time, and can also help improve the condition of their respiratory system. [Brief explanation of the drawing]

[0026] [Figure 1] This is a perspective view illustrating an oxygen saturation measuring device according to an embodiment of the present disclosure. [Figure 2] This is a cross-sectional view illustrating the oxygen saturation measuring device according to this embodiment. [Figure 3] This is a plan view illustrating the sensor unit of the oxygen saturation measuring device according to this embodiment. [Figure 4] This is a cross-sectional view taken along line 4-4 in Figure 3. [Figure 5] This graph illustrates the time-series changes in oxygen saturation levels of the arteries in the fingertips and the time-series changes in oxygen saturation levels of the arteries in the wrist. [Figure 6] This is a flowchart illustrating the oxygen saturation measurement method using the oxygen saturation measuring device according to this embodiment. [Figure 7] This is a perspective view illustrating the state in which the oxygen saturation of the artery in the fingertip is measured using the second sensor unit in the oxygen saturation measurement method according to this embodiment. [Figure 8] This flowchart illustrates the process of measuring the oxygen saturation of the fingertip artery using the second sensor unit in a modified oxygen saturation measurement method. [Modes for carrying out the invention]

[0027] This embodiment is described below. In the following drawings, identical and similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of thickness of each device and component, etc., may differ from reality. Therefore, specific thicknesses and dimensions should be determined by referring to the following explanation. Furthermore, there are parts where the relationships and ratios of dimensions differ between drawings.

[0028] <Oxygen saturation measuring device> The structure of the oxygen saturation measuring device 10 according to this embodiment will be described with reference to Figures 1 to 5. As shown in Figure 1, the oxygen saturation measuring device 10 according to this embodiment includes a band 12, a first sensor unit 11, a notification unit 26, and a second sensor unit 21.

[0029] (band) As shown in Figure 2, the band 12 is wrapped around the wrist of the person being measured. The material of the band 12 can be anything, such as resin, fabric, or metal. The band 12 is also provided with a clasp for adjusting and securing its length when wrapped around the wrist.

[0030] (First sensor unit) As shown in Figures 1 and 2, the first sensor unit 11 is attached to the inside of the band 12, that is, to the side of the band 12 that contacts the wrist. In this disclosure, the attachment position of the first sensor unit is not limited to the inside of the band 12, but may be on the outside of the band 12. The first sensor unit 11 acquires the pulse wave signal of the artery in the wrist and measures the oxygen saturation of the artery in the wrist based on the acquired pulse wave signal.

[0031] Specifically, the first sensor unit 11 of this embodiment is composed of a base 14, a contact portion 16, a light-emitting element, a light-receiving element, and a calculation unit 18. The calculation unit 18 is housed inside the housing 25. In this disclosure, the first sensor unit 11 can be configured arbitrarily as long as it can acquire the pulse wave signal of the artery in the wrist.

[0032] In the oxygen saturation measuring device 10 illustrated in Figure 2, the following photodetectors are provided: a first photodetector PD1, a second photodetector PD2, a third photodetector PD3, a fourth photodetector PD4, and a fifth photodetector PD5. Furthermore, the inside of the wrist in Figure 2 is illustrated with the radius 20, the radial styloid process 20A, the flexor carpi radialis tendon 22, and the radial artery 24.

[0033] (base) The base portion 14 is provided on the inner surface of the band 12. Specifically, in this embodiment, the base portion 14 can be fixed to the band 12, for example, by adhesive. However, the fixing method is not limited to adhesive; a fixing plate-like member may be interposed between the band 12 and the circuit board, and the circuit board may be fixed to the plate-like member by screws or the like.

[0034] The base portion 14 has a flat bonding surface 14A between the band 12 and the contact portion 16. In this embodiment, both the light-emitting element and the light-receiving element are bonded to the bonding surface 14A of the base portion 14. In this disclosure, it is sufficient that at least one of the light-emitting element and the light-receiving element is bonded to the bonding surface 14A.

[0035] Furthermore, in this disclosure, the base portion 14 may be the circuit board itself on which the light-emitting element and the light-receiving element are mounted, or it may be a combination of the circuit board and a fixing plate-shaped member, or a combination of the circuit board and a buffer member, etc. In other words, the base portion 14 of this disclosure only needs to have a bonding surface 14A to which at least one of the light-emitting element and the light-receiving element is bonded.

[0036] As shown in Figure 3, the light-emitting element and the light-receiving element are arranged on the bonding surface 14A of the base 14. Note that the circuit board on which the light-emitting element and the light-receiving element are mounted is not shown.

[0037] (light-emitting element) The light-emitting element is an electronic component such as a light-emitting diode (LED). The light-emitting element is positioned at a predetermined location relative to the contact portion 16 and irradiates light onto the artery of the wrist. In this embodiment, the light-emitting element consists of a first light-emitting element LED1, a second light-emitting element LED2, and a third light-emitting element LED3. The first light-emitting element LED1, the second light-emitting element LED2, and the third light-emitting element LED3 are positioned apart from each other and arranged along the circumferential direction of the wrist. In this disclosure, the number of light-emitting elements can be one or more, as is arbitrary.

[0038] As shown in Figure 3, the first light-emitting element LED1, the second light-emitting element LED2, and the third light-emitting element LED3 each have a set of light sources including one or more red light sources (RED) and one or more infrared light sources (IR). In other words, in this embodiment, two types of light are emitted from one light-emitting element. The two types of reflected light received by one photodetector are then used to measure oxygen saturation. In this disclosure, the types of light sources are not limited to two; there may be one type, or three or more types.

[0039] (Principle of measuring oxygen saturation) Here, we will explain the measurement principle of oxygen saturation in this embodiment, which uses two types of irradiated light and two types of reflected light. Specifically, for example, red light in the wavelength range of approximately 620 nm to 700 nm has the characteristic that its absorbance changes greatly depending on the presence or absence of oxygen bound to hemoglobin. On the other hand, near-infrared light in the wavelength range of approximately 850 nm to 960 nm has the characteristic that its absorbance does not change greatly depending on the presence or absence of oxygen bound to hemoglobin.

[0040] Therefore, the intensity of the pulse wave signal of the reflected red light is monitored over time, and the fluctuating component (AC) and the non-fluctuating fixed component (DC) of the pulse wave signal are calculated. Then, by dividing the fluctuating component by the fixed component (AC / DC), the red light perfusion index (PI) value is obtained. REDIt is calculated as such. Also, similar to the case of red light, by monitoring the change in the intensity of the pulse wave signal of the reflected light of near-infrared light over time, the PI value (PI IR ) of the reflected light of near-infrared light is calculated.

[0041] Then, the ratio (PI RED ) of the PI value of red light (PI IR ) and the PI value of near-infrared light (PI RED / PI IR ) is calculated. And by using the calculated ratio (PI RED / PI IR ) in the following formula (1), the oxygen saturation can be calculated. Oxygen saturation [%]=a×(PI RED / PI IR )+b ··· Formula (1) The coefficients a and b in Formula (1) can be obtained by experiments. In the present disclosure, the method for measuring oxygen saturation is not limited to this, and other methods may also be used.

[0042] (Light receiving element) The light receiving element is an electronic component such as a photodiode (PD) for example. The light receiving element is arranged at a preset position with respect to the contact portion 16, and receives the reflected light from the artery of the wrist through the contact surface 16A of the contact portion 16. The first light receiving element PD1, the second light receiving element PD2, the third light receiving element PD3, the fourth light receiving element PD4, and the fifth light receiving element PD5 are arranged apart from each other and are arranged along the circumferential direction of the wrist. In the present disclosure, the number of light receiving elements is arbitrary and is one or more.

[0043] In the present embodiment, one "sensor unit" is constituted by one or more light emitting elements and one or more light receiving elements corresponding to the one or more light emitting elements. In the present disclosure, a plurality of sensor units may be provided. Also, the number of light emitting elements and the number of light receiving elements included in one "sensor unit" can both be arbitrarily set.

[0044] Furthermore, although the oxygen saturation measuring device 10 according to this embodiment is a reflective type in which the intensity of the pulse wave signal is measured by reflected light, this disclosure is not limited to the reflective type, and may also be a transmissive type in which the intensity of the pulse wave signal is measured by transmitted light.

[0045] (Light-blocking part) As shown in Figure 4, a light-shielding portion 14B is provided between the light-emitting element and the light-receiving element in the base portion 14. The light-shielding portion 14B prevents the light-receiving element from directly receiving light from the light-emitting element. It is preferable to use the light-shielding portion 14B while keeping the distance between the light-emitting element and the light-receiving element as close as possible, as this shortens the optical path length and, as a result, improves measurement accuracy.

[0046] (Contact area) The contact portion 16 is attached to the band 12. The contact portion 16 is also transparent to light irradiated onto the artery in the wrist and to light reflected from the artery in the wrist. Specifically, for example, a light-transmitting material such as a lens may be used. In Figure 4, the contact portion 16 positioned above the light-emitting element is, for example, a diffusion lens capable of expanding the irradiation area. Although not shown in the figure, a diffusing agent may be positioned above the light-emitting element together with the diffusion lens, or in place of the diffusion lens. In Figure 4, the contact portion 16 positioned above the light-receiving element may be, for example, a focusing lens capable of collecting reflected light.

[0047] Furthermore, the contact portion 16 has a contact surface 16A that protrudes from the band 12 toward the wrist. In this embodiment, the contact surface 16A has a curved shape. The contact surface 16A comes into contact with the skin of the wrist when measuring oxygen saturation.

[0048] As shown in Figures 3 and 4, the contact portion 16 is dome-shaped. On the contact surface 16A, which corresponds to the outer surface of the dome, the central part in the left-right direction (direction E of forearm extension) in Figure 4 is flat, and both the left and right ends each have a certain curvature, resulting in a smooth curve without sharp edges. A curvature of, for example, 0.167 or more is preferable from the viewpoint of improving wearability for the person being measured. Although not shown in the figures, similarly, the central part of the contact portion 16 in the circumferential direction C of the wrist is flat, and both the left and right ends each curve smoothly.

[0049] Furthermore, in this disclosure, the contact surface does not have to have a flat portion. The contact surface may have a curved shape, while having a constant curvature overall.

[0050] In this specification, the "direction of forearm extension E" coincides with the direction of extension of the radius 20, the ulna, and the arteries. Furthermore, the "direction of forearm extension E" is strictly different for each individual being measured. In other words, the "direction of forearm extension E" is not uniquely determined by coordinates in three-dimensional space, but is individually determined based on the direction of extension of the radius 20, the ulna, and the arteries for each individual being measured.

[0051] (Enclosure) The housing 25 is attached to the band 12 and contacts the back of the wrist, which is the outer surface of the person being measured. The material of the housing 25 can be any material, such as resin or metal. Note that the housing 25 is not essential in this disclosure.

[0052] (calculation section) In this embodiment, the calculation unit 18 is provided in the housing 25. A light-receiving element is connected to the calculation unit 18. Data of the pulse wave signal of reflected light is input to the calculation unit 18 from the light-receiving element over time.

[0053] The arithmetic unit 18 is configured as a computer, for example, equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), storage device, I / O ports, etc. The RAM, storage device, I / O ports, etc. are configured to exchange data with the CPU via an internal bus. Based on the pulse wave signal acquired from the reflected light, the arithmetic unit 18 measures the oxygen saturation of the radial artery 24 irradiated with light, using a method such as a ratio of PI values.

[0054] (News Department) As shown in Figure 1, the notification unit 26 is positioned on the surface of the housing 25 opposite to the wrist. The notification unit 26 is an image display device formed by, for example, liquid crystal. The notification unit 26 displays the calculation results from the calculation unit 18 to the outside so that the person being measured can see them.

[0055] The notification unit 26 may be provided with a storage device for temporarily storing measurement results. In this disclosure, if the housing 25 is not provided, the calculation unit can be arranged as part of the calculation device, for example, on the contact part or base. Similarly, the storage device can also be arranged on a component other than the housing, such as the contact part or base. In this disclosure, even if the notification unit 26 is not provided on the housing 25, it is possible to obtain the calculation results from the calculation unit 18 by using, for example, a communication unit connected to the calculation unit 18 and capable of communicating with the outside.

[0056] The notification unit 26 alerts the person being measured to a potential respiratory problem if the oxygen saturation measured by the first sensor unit 11 meets a preset condition. Specifically, if the measured oxygen saturation does not reach a preset standard value, the notification unit 26 alerts the person being measured to prompt them to measure their oxygen saturation at the fingertip.

[0057] (Reference value) In this embodiment, the reference value is 90% oxygen saturation. The notification unit 26 issues a warning prompting the person being measured to measure their oxygen saturation at the fingertip if the oxygen saturation is less than 90%. In other words, the reference value in this embodiment is the lower limit of oxygen saturation. Furthermore, the condition in this embodiment is that the measured oxygen saturation does not reach the lower limit.

[0058] In this embodiment, when the reference value is oxygen saturation, it is preferable that the reference value used as the lower limit for determining whether or not to issue a warning be set within the range of 90% or more and 94% or less. In Figure 5, the trajectory of data obtained by continuously measuring oxygen saturation over time using the first sensor unit 11 at the fingertip is illustrated by a solid line. The trajectory of data obtained by continuously measuring oxygen saturation over time using the first sensor unit 11 at the wrist is illustrated by a dashed line.

[0059] Furthermore, in this disclosure, the criteria for determining whether or not to issue a warning are not limited to the range of 90% or more and 94% or less, but can be appropriately changed according to the respiratory condition of the person being measured. For example, in the case of a patient suffering from a certain viral infection, the oxygen saturation may chronically be around 92% to 93%. Therefore, in this disclosure, as another example of a criteria, the criteria can be set by a combination of an initial value and a correction value that indicates the decrease from the initial value. The initial value and the correction value can each be set in advance for each person being measured according to the respiratory condition of the person being measured.

[0060] Specifically, as an initial value, the average value of oxygen saturation measured within a certain period, such as the most recent month before setting, can be used. For example, if the person being measured is suffering from a specific viral infection, the initial value can be set to, for example, 92%, but in practice, it is not limited to this and can vary depending on the person being measured or the respiratory condition of the person being measured.

[0061] Furthermore, the correction value can be empirically set based on clinical data or analytical data obtained from a group of subjects who have similar personal information, such as the subject's nationality, sex, age, height, weight, and current respiratory status. The correction value can be set to, for example, 2%, but in practice it is not limited to this and may vary depending on the subject or the subject's respiratory status.

[0062] As described above, if the person being measured is suffering from a specific viral infection, and the set initial value is, for example, 92%, and the set correction value is 2%, then a value of "90%" can be obtained by subtracting the correction value from the initial value. The obtained value of "90%" can be set as the criterion value for determining whether or not to issue a warning in oxygen saturation measurement.

[0063] Furthermore, the disclosers evaluated the agreement between the measurement accuracy at the wrist and the measurement accuracy at the fingertips using a Brand-Altman analysis on five subjects. Specifically, while each subject held their breath, the first sensor unit 11 was used to acquire the temporal changes in oxygen saturation measurements at the wrist and the temporal changes in oxygen saturation measurements at the fingertips.

[0064] In the Brand-Altman analysis, the average oxygen saturation value of five subjects was calculated, and the range of positive and negative errors from the calculated average was calculated within the range of oxygen saturation between 80% and 100%. The range of errors when measured at the fingertip position was approximately 3.0%.

[0065] On the other hand, the error spread when measuring at the wrist was approximately 6.0%. In other words, it was found that the error spread when measuring at the wrist was about twice as large as when measuring at the fingertips. Furthermore, the analysis revealed that, in particular, within the range of oxygen saturation below 90%, the error in measurements at the wrist was larger than the error in measurements at the fingertips.

[0066] As shown in Figure 5, when the reference oxygen saturation level is below 90%, the measurement accuracy of oxygen saturation measured at the wrist is lower than that measured at the fingertip. Arterial blood perfusion at the fingertip is greater than that at the wrist. Therefore, the accuracy of determining the respiratory condition of the subject decreases. On the other hand, when the reference oxygen saturation level for determining whether or not to issue a warning exceeds 94%, the range in which the respiratory condition is diagnosed as normal increases, leading to an increase in the number of warnings.

[0067] In this disclosure, the conditions used to determine whether or not to issue a warning are not limited to the lower limit of oxygen saturation, but can be set arbitrarily. For example, the conditions may be set using biological information other than oxygen saturation, such as respiratory rate and cough count. For example, the respiratory rate and cough count of a person being measured are biological information that can be obtained from the pulse wave signal.

[0068] Furthermore, conditions may be set using arbitrary vascular information other than pulse wave signals, such as sound wave information of the sound of blood flowing through an artery. For example, if the sound of blood flowing through an artery is used, the first sensor unit 11 may be equipped with a microphone that has a sound collection function. As sound wave information, for example, frequency and amplitude can be used. It is also possible to obtain the number of coughs from the sound of blood flowing through an artery. Based on the sound wave information from the sound of blood flowing through an artery, a reference value used in setting the conditions can be set.

[0069] In this embodiment, the warning is image information including characters and graphics. However, in this disclosure, the warning is not limited to image information and may be given by light, such as illumination or flashing of a specific warning color. The warning may also be given by sound or vibration.

[0070] (Second sensor unit) As shown in Figures 1 and 2, the second sensor unit 21 is mounted on the outside of the band 12, that is, on the side of the band 12 that does not come into contact with the wrist, in a position easily visible to the person being measured. The second sensor unit 21 measures the oxygen saturation of the arteries in the fingertips of the person being measured. In this embodiment, the second sensor unit 21 is composed of a measurement unit 28 and a calculation unit 18. The measurement unit 28 has a panel that serves as a touchscreen interface. In this disclosure, the mounting position of the second sensor unit is not limited to the outside of the band 12. For example, it can be mounted on the inside of the band 12 if a non-energized state is maintained to the second sensor unit while it is in contact with the wrist, thereby preventing malfunction of the touchscreen.

[0071] The measurement unit 28 is equipped with a light energy source (not shown), and two wavelengths of light for oxygen saturation measurement are emitted from the light energy source inside the measurement unit 28. When the fingertip of the person being measured comes into contact with the measurement unit 28, attenuation occurs in each of the two wavelengths of light. The measurement unit 28 is also equipped with a detection unit (not shown) that detects the attenuated light, and the detection unit is connected to the calculation unit 18. The calculation unit 18 measures the oxygen saturation in the arterial blood at the fingertip based on the attenuated light.

[0072] In this disclosure, the second sensor unit can be configured arbitrarily, as long as it can measure the oxygen saturation of the artery at the fingertip. For example, the oxygen saturation measurement method in the second sensor unit may be either reflective or transmissive. Furthermore, known touchscreen interface technology may be applied to the second sensor unit.

[0073] <Method for measuring oxygen saturation> Next, an example of an oxygen saturation measurement method using the oxygen saturation measuring device 10 according to this embodiment will be described with reference to Figures 2, 6, and 7.

[0074] First, as shown in step S10 in Figure 6, the person being measured wraps the band 12 of the oxygen saturation measuring device 10 around their wrist. The artery to be measured is, for example, the radial artery 24. In this disclosure, the artery to be measured is not limited to the radial artery 24, but may be any other artery. Then, the contact surface 16A is brought into contact with the skin near the radial styloid process 20A on the inside of the wrist.

[0075] Next, as shown in Figure 2, the subject places the contact portion 16 inside the depression in the gap between the radial styloid process 20A and the flexor carpi radialis tendon 22. Then, as shown in step S20, the subject uses the first sensor unit 11 to acquire the pulse wave signal of the artery in their wrist. Based on the acquired pulse wave signal, the oxygen saturation of the artery is then measured.

[0076] Specifically, light is shone from the light-emitting element onto the radial artery 24 located below the depression in Figure 2. The reflected light from the radial artery 24 is then received by the light-receiving element. Based on the pulse wave signal obtained from the reflected light, the calculation unit 18 measures the oxygen saturation.

[0077] Next, as shown in step S30, the calculation unit 18 compares the measured oxygen saturation with a preset reference value. If the compared oxygen saturation is equal to or greater than the reference value, it is determined that a warning is not necessary. The process then proceeds to step S20, and the measurement of oxygen saturation is repeated. On the other hand, if the compared oxygen saturation does not reach the reference value, as shown in step S40, the calculation unit 18 notifies the person being measured of a warning.

[0078] In this disclosure, for example, the power supply to the second sensor unit 21 may be controlled such that power is cut off until a warning is issued, and power is supplied to the second sensor unit 21 after the warning is issued. By controlling the power supply to the second sensor unit 21, power consumption can be suppressed.

[0079] Next, as shown in step S50, the person being measured measures the oxygen saturation of the artery in their fingertip using the second sensor unit 21. Specifically, they place their fingertip in contact with the measurement unit 28 of the second sensor unit 21. The measured oxygen saturation value is displayed on the notification unit 26, which serves as a display unit. In this disclosure, the display unit that displays the measured oxygen saturation value measured by the second sensor unit 21 may be integrated with the notification unit 26 as in this embodiment, or it may be provided separately from the notification unit 26.

[0080] Next, as shown in step S60 in Figure 6, the calculation unit 18 stores the measured values ​​in a storage device. For example, the stored measured values ​​can be displayed on the notification unit 26 during a medical examination by a doctor or other medical professional, thereby contributing to the examination.

[0081] In this disclosure, the storage device may store additional data, such as the name of the sensor unit used for measurement and the date and time, along with the measured values. In this disclosure, the storage device may also store the measured values ​​measured by the first sensor unit 11. In this disclosure, for example, after the processing in step S60, the processing from step S20 onward may be repeated.

[0082] (Effects and Benefits) In the first embodiment, a band 12 is wrapped around the wrist of the person being measured, and a pulse wave signal from the artery in the wrist is acquired by a first sensor unit 11 attached to the band 12. Based on the acquired pulse wave signal, the oxygen saturation of the artery in the wrist is measured. In other words, since the oxygen saturation is measured at the wrist, it is less likely to interfere with the person's work or daily activities compared to when the oxygen saturation is measured at the fingertips, and the oxygen saturation measuring device 10 can be used to measure continuously over time.

[0083] Furthermore, the measured oxygen saturation level in the wrist artery is compared to a predetermined reference value, and if the measured oxygen saturation level does not reach the reference value, the subject is notified of a warning indicating the possibility of respiratory problems. This warning encourages the subject to take action, such as consulting a doctor, and as a result, can lead to an improvement in their respiratory condition.

[0084] Furthermore, in this embodiment, the first sensor unit 11 is attached to the inside of the band 12, that is, the side of the band 12 that contacts the wrist. This makes it easier to measure the radial artery 24, which is close to the inner surface of the wrist.

[0085] Furthermore, in this embodiment, if the oxygen saturation level is below 90%, the person being measured is notified as a warning to prompt them to measure their oxygen saturation level at the fingertip. This allows for more accurate measurement of oxygen saturation.

[0086] Furthermore, the oxygen saturation measuring device 10 according to this embodiment further includes a second sensor unit 21 attached to the band 12 for measuring the oxygen saturation of the arteries in the fingertips. Therefore, both continuous measurement of oxygen saturation over time at the wrist and measurement of oxygen saturation with higher accuracy at the fingertips can be achieved using a single oxygen saturation measuring device 10. In other words, there is no need to prepare a separate oxygen saturation measuring device for measuring the oxygen saturation of the arteries in the fingertips.

[0087] Furthermore, even if a high-precision oxygen saturation measuring device, such as one that measures at the fingertip, is located away from the person being measured, the person being measured does not need to move to pick up the device. Therefore, after a warning is issued, measurement of arterial oxygen saturation at the fingertip can be started immediately. In addition, since the person being measured does not have to move to pick up the oxygen saturation measuring device, it is easier to establish the habit of measuring oxygen saturation.

[0088] Furthermore, in this embodiment, the second sensor unit 21 is mounted on the outside of the band 12, that is, on the side of the band 12 that does not come into contact with the wrist, in a position that is easily visible to the person being measured. Therefore, compared to the case where the second sensor unit 21 is mounted on the inside of the band 12, it becomes easier for the person being measured to handle the second sensor unit 21.

[0089] Furthermore, in this embodiment, the notification unit 26 and the display unit are integrated. Therefore, the overall dimensions of the oxygen saturation measuring device are reduced compared to the case where the notification unit 26 and the display unit are separate. As a result, the oxygen saturation measuring device can be configured compactly.

[0090] Furthermore, according to the oxygen saturation measurement method using the oxygen saturation measuring device 10 of this embodiment, it is possible to measure oxygen saturation continuously over time and to improve the respiratory condition.

[0091] (modified version) In this embodiment, the condition in which a warning is issued to measure oxygen saturation at the fingertip is described as when the oxygen saturation measured at the artery in the subject's wrist does not reach a reference value, but this disclosure is not limited to this. For example, Figure 8 illustrates a modified oxygen saturation measurement method in which a warning is issued based on the subject's respiratory status.

[0092] The modified oxygen saturation measurement method mainly differs from the oxygen saturation measurement method according to this embodiment in that it includes steps S21 and S31 in Figure 8 instead of steps S20 and S30 in Figure 6. In steps S21 and S31, respiratory rate is used instead of oxygen saturation. The contents of the steps other than steps S21 and S31 are the same as the corresponding steps with the same names in Figure 6, so redundant explanations are omitted.

[0093] In a modified example, the respiratory rate of the person being measured is detected, as shown in step S21 in Figure 8. Respiratory rate detection can be performed, for example, by acquiring a pulse wave signal from the artery in the person's wrist using the first sensor unit 11, and based on the acquired pulse wave signal.

[0094] Next, as shown in step S31, the detected respiratory rate is compared with a preset reference respiratory rate. If the compared respiratory rate is equal to or greater than the reference rate, it is determined that no warning is necessary. If it is determined that no warning is necessary, the process proceeds to step S21, and the respiratory rate measurement is repeated.

[0095] On the other hand, if the compared respiratory rate does not reach the reference value, a warning is issued to the subject as shown in step S40. The process is then carried out in the same manner as in this embodiment. In a modified example, even when oxygen saturation cannot be measured, the respiratory rate can be used to determine the respiratory condition of the subject. In this disclosure, as in the modified example, conditions can be set in advance using biological information other than oxygen saturation.

[0096] <Other Embodiments> While this disclosure has been described by the embodiments disclosed above, the descriptions and drawings that constitute part of this disclosure should not be understood as limiting this disclosure. For example, in this disclosure, the means for acquiring the pulse wave signal of the arteries in the wrist is not limited to a wristwatch-type device using a belt. For example, the oxygen saturation measuring device may be a portable device that can be placed close to the wrist. Also, the means for acquiring the pulse wave signal of the arteries in the wrist does not have to be a dedicated device for measuring oxygen saturation, but may be, for example, a general-purpose device with an oxygen saturation measuring function. In other words, the method for measuring oxygen saturation is not limited to a device.

[0097] Furthermore, if a warning is issued based on the respiratory status of the person being measured, a necklace-type respiratory rate measuring device that can be placed close to the person's chest may also be used. In addition, the notification unit is not essential in this disclosure. For example, the oxygen saturation measured by the second sensor unit may be transmitted externally via a communication function, and the transmitted oxygen saturation may be displayed on a display device that serves as an external notification unit. Furthermore, this disclosure may be configured without the use of the second sensor unit.

[0098] This disclosure includes various embodiments not described above, and the technical scope of this disclosure is defined solely by the inventive features of the claims that are reasonable from the above description. [Explanation of Symbols]

[0099] 10. Oxygen saturation measuring device 11. First Sensor Unit 12 bands 14 Base 14A Joint surface 14B Light shielding part 16 Contact area 16A contact surface 18 Arithmetic section 20 Radius 20A Radial styloid process 21 Second Sensor Unit 22. Flexor carpi radialis tendon 24 Radial artery 25 cabinets 26 Hochi Department 28 Measuring part C. Circumferential direction of the wrist E. Direction of extension of the forearm IR infrared light source LED1 First light-emitting element LED2 (Second Light-Emitting Device) LED3 Third light-emitting element PD1 First photodetector PD2 Second photodetector PD3 Third photodetector PD4 (Fourth photodetector) PD5 Fifth photodetector RED (Red Light Source)

Claims

1. A band that is wrapped around the wrist of the person being measured, A first sensor unit is attached to the inside of the band to acquire the pulse wave signal of the artery in the wrist and to measure the oxygen saturation of the artery in the wrist based on the acquired pulse wave signal. A notification unit that alerts the person being measured to a potential respiratory problem when the oxygen saturation level measured by the first sensor unit meets a preset condition, A second sensor unit, attached to the outside of the band, measures the oxygen saturation of the artery in the fingertip of the person being measured. An oxygen saturation measuring device equipped with the following features.

2. If the oxygen saturation measured by the first sensor unit does not reach a preset reference value, the notification unit provides a warning prompting the person being measured to measure the oxygen saturation at the fingertip using the second sensor unit. The oxygen saturation measuring device according to claim 1.

3. A band that is wrapped around the wrist of the person being measured, A first sensor unit is attached to the inside of the band to acquire the pulse wave signal of the artery in the wrist and to measure the oxygen saturation of the artery in the wrist based on the acquired pulse wave signal. A notification unit that alerts the person being measured to a potential respiratory problem when the oxygen saturation level measured by the first sensor unit meets a preset condition, A second sensor unit, attached to the outside of the band, measures the oxygen saturation of the artery in the fingertip of the person being measured. A display unit that displays the oxygen saturation level measured by the second sensor unit, An oxygen saturation measuring device equipped with the following features.

4. The notification unit and the display unit are an integrated unit. The oxygen saturation measuring device according to claim 3.

5. A band that is wrapped around the wrist of the person being measured, A first sensor unit is attached to the inside of the band to acquire the pulse wave signal of the artery in the wrist and to measure the oxygen saturation of the artery in the wrist based on the acquired pulse wave signal. A notification unit that, when the oxygen saturation measured by the first sensor unit meets a preset condition, notifies the person being measured of a warning indicating the possibility of respiratory distress, A method for measuring oxygen saturation using an oxygen saturation measuring device comprising a second sensor unit attached to the outside of the band for measuring the oxygen saturation of the artery at the fingertip of the person being measured, The first sensor unit acquires the pulse wave signal of the artery in the wrist of the person being measured. The first sensor unit measures the oxygen saturation of the artery based on the acquired pulse wave signal, The notification unit notifies the person being measured of a warning when the measured oxygen saturation level meets a preset condition. The second sensor unit measures the oxygen saturation of the fingertip of the person being measured. Method for measuring oxygen saturation.

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