pulse oximeter

Abstract

This invention provides a pulse oximeter that offers high accuracy in measuring oxygen saturation and provides continuous data suitable for measuring the oxygen saturation decline index. [Solution] The pulse oximeter includes: a saturation measurement unit 21 that measures the blood oxygen saturation of a subject 9 from detection signals of a red light sensor 12 and an infrared light sensor 13 and converts them into a measurement data group 211; an abnormal value detection unit 22 that detects abnormal values ​​221 that appear in the measurement data group 211; a first data processing unit 23 that generates a first data group 233 by removing abnormal value intervals 232 that include the abnormal values ​​221 and adjacent time ranges 231 of a predetermined length; a second data processing unit 24 that generates a second data group 243 by removing low reliability intervals 242 in which the reliability index 241 calculated on the first data group 233 is lower than a predetermined threshold L; and a third data processing unit 25 that performs data interpolation processing on the second data group 243 to generate a third data group 252 of a predetermined time length.

Description

Technical Field

[0001] The present invention relates to a pulse oximeter.

Background Art

[0002] A pulse oximeter measures the arterial blood oxygen saturation (SpO2) by irradiating a finger with red light and a near-infrared light source and detecting the light transmitted through the finger (see Patent Document 1). When performing an examination of the oxygen saturation decrease index, which is an indicator of sleep apnea syndrome, the arterial blood oxygen saturation of a subject during sleep is measured using a pulse oximeter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When measuring the arterial blood oxygen saturation of a subject during sleep, if the subject's body moves during the measurement, in a pulse oximeter, the intensity variation of the reflected light of the light in the skin due to the body movement is mixed as a disturbance signal (body movement artifact). When such a body movement artifact occurs, the pulsation signal to be detected by the pulse oximeter is masked, and as a result, there is a problem that the measurement accuracy of the arterial blood oxygen saturation decreases. Regarding the problem of the decrease in the measurement accuracy of the arterial blood oxygen saturation by the above-described pulse oximeter, a process of removing abnormal values due to body movement artifacts and the like from the measurement data is performed. However, for the analysis of the oxygen saturation decrease index, which is an examination index of sleep apnea syndrome, data for a certain period of time is required. When abnormal values are frequently removed from the measurement data, the remaining measurement data becomes discrete, and there is a problem that continuous data of a sufficient length to obtain the oxygen saturation decrease index cannot be obtained. [Means for solving the problem]

[0005] A pulse oximeter according to a first aspect of this disclosure includes: a red light sensor that detects the red light transmitted or reflected by irradiating a subject with red light; an infrared light sensor that detects the infrared light transmitted or reflected by irradiating a subject with infrared light; and a control device that processes the detection signals of the red light sensor and the infrared light sensor, wherein the control device includes: a saturation measurement unit that measures the blood oxygen saturation of the subject from the detection signals and records it as a group of measurement data; an abnormal value detection unit that detects abnormal values ​​appearing in the group of measurement data; and a control device that processes the abnormal values ​​detected by the abnormal value detection unit. The system includes: a first data processing unit that calculates an abnormal value interval including adjacent time intervals of a predetermined length that are temporally adjacent, and generates a first data group by removing the data from the measurement data group. a second data processing unit that calculates a reliability index by convolution on the first data group and generates a second data group by removing the data from the first data group that are in low reliability intervals where the reliability index is lower than a predetermined threshold. a third data processing unit that performs data interpolation processing on the removed abnormal value intervals and low reliability intervals on the second data group and generates a third data group with a predetermined time length.

[0006] A pulse oximeter according to a second aspect of the present disclosure includes a red light sensor that detects the red light transmitted or reflected by irradiating a subject with red light, an infrared light sensor that detects the infrared light transmitted or reflected by irradiating a subject with infrared light, a control device that processes the detection signals from the red light sensor and the infrared light sensor, and a display unit that displays the information obtained by the control device. The control device measures the blood oxygen saturation of the subject from the detection signals to generate a group of measurement data, removes abnormal values ​​from the group of measurement data to obtain a group of oxygen saturation data, calculates a reliability index for the group of oxygen saturation data, displays the group of oxygen saturation data and the reliability index on the display unit on the same time axis, and performs data interpolation processing on the oxygen saturation data for the range in the group of oxygen saturation data where the reliability index exceeds a predetermined threshold, displays the threshold on the display unit, and further displays the interpolated portion in a different display mode from the oxygen saturation data group.

[0007] A pulse oximeter according to a third aspect of this disclosure includes a red light sensor that detects the red light transmitted or reflected by irradiating a subject with red light, an infrared light sensor that detects the infrared light transmitted or reflected by irradiating a subject with infrared light, a control device that processes the detection signals from the red light sensor and the infrared light sensor, and a display unit that displays the information obtained by the control device. The control device measures the blood oxygen saturation of the subject from the detection signals to generate a group of measurement data, calculates a reliability index for the group of measurement data, displays the group of measurement data, the reliability index, and the time on the display unit, and displays the range of the group of measurement data that exceeds a predetermined threshold and the range that falls below the threshold in different display modes. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram showing a pulse oximeter according to one embodiment of the present disclosure. [Figure 2]A schematic diagram showing the usage state of the pulse oximeter according to the above embodiment. [Figure 3] A block diagram showing the control device for the pulse oximeter according to the above embodiment. [Figure 4] A graph showing the measurement data set and abnormal values ​​in the above embodiment. [Figure 5] A graph showing the abnormal value interval in the above embodiment. [Figure 6] A partially enlarged graph of the outlier interval in the above embodiment. [Figure 7] A graph showing the first data group in the above embodiment. [Figure 8] A graph showing the reliability index in the above embodiment. [Figure 9] A graph showing the second data group in the above embodiment. [Figure 10] A graph showing the third data group in the above embodiment. [Figure 11] A schematic diagram showing the display screen in the above embodiment. [Figure 12] A flowchart illustrating the process in the above embodiment. [Figure 13] A schematic diagram illustrating another embodiment of the present invention. [Modes for carrying out the invention]

[0009] An embodiment of this disclosure will be described below. In Figures 1 and 2, the pulse oximeter 1 has a sensor unit 10 and a control device 20. The sensor unit 10 and the control device 20 are housed in a case 2, and a display unit 30 is connected to the control device 20.

[0010] The sensor unit 10 is positioned on the surface of the case 2 and is held in close contact with the subject 9, such as the user's fingers, during measurement. The sensor unit 10 is equipped with a green light source 111, a red light source 112, an infrared light source 113, and a photodetector 110. The green light source 111, the red light source 112, and the infrared light source 113 are, for example, LEDs (light emitting diodes) or laser diodes. It is desirable that the emission wavelength of the green light source 111 is 500 nm to 600 nm, the emission wavelength of the red light source 112 is 600 nm to 800 nm, and the emission wavelength of the infrared light source 113 is 800 nm to 1000 nm. The photodetector 110 is, for example, a silicon photodiode. The green light source 111, the red light source 112, the infrared light source 113, and the photodetector 110 of the sensor unit 10 are covered with a cover (not shown) of a transparent resin molding plate such as acrylic or polycarbonate on the surface.

[0011] In the sensor unit 10, the green light source 111, the red light source 112, and the infrared light source 113 emit light in order under the control of the control device 20, and the light rays from each are reflected by the subcutaneous tissue of the subject 9 and returned to the photodetector 110. The control device 20 acquires the detection signal of the photodetector 110 as the detection signal of green light, the detection signal of red light, and the detection signal of infrared light from the emission timing of each light emitting element. The green light source 111 and the photodetector 110 constitute the green light sensor 11, the red light source 112 and the photodetector 110 constitute the red light sensor 12, and the infrared light source 113 and the photodetector 110 constitute the infrared light sensor 13. The sensor unit 10 further includes an acceleration sensor 14 installed in the case 2.

[0012] The control device 20 is composed of a small computer system, and includes a memory for storing various data, and a processor for realizing a desired function (see FIG. 3) by executing a program stored in the memory. In the case 2, in addition to storing a battery that serves as the power source for the sensor unit 10 and the control device 20, input / output terminals of the control device 20 and the like are installed (not shown).

[0013] The display unit 30 is connected to the control device 20 by wired or wireless signal means and can display measurement results and the like by the control device 20. As the display unit 30, for example, in addition to a general-purpose image display panel, a portable information terminal such as a so-called smartphone can be used.

[0014] In FIG. 3, the control device 20 functions as a saturation measurement unit 21, an outlier detection unit 22, a first data processing unit 23, a second data processing unit 24, a third data processing unit 25, and a display control unit when a processor executes a program. The saturation measurement unit 21 controls the green light sensor 11, the red light sensor 12, and the infrared light sensor 13 of the sensor unit 10 connected to the control device 20 and acquires (receives) a detection signal.

[0015] The saturation measurement unit 21 measures the blood oxygen saturation of the subject 9 from the detection signals of the red light sensor 12 and the infrared light sensor 13 and records it in the memory as a measurement data group 211. The detection signals of the red light sensor 12 and the infrared light sensor 13 are photoplethysmogram signals based on the red light and infrared light that have passed through the subcutaneous tissue of the subject 9, and the saturation measurement unit 21 measures the oxygen saturation from the pulse signals of the red light and infrared light and records it in the memory as a measurement data group 211.

[0016] The outlier detection unit 22 detects an outlier 221 (see FIG. 4) that appears in the measurement data group 211. For this purpose, the outlier detection unit 22 processes the detection signal of the acceleration sensor 14, detects body movement artifacts such as changes in the posture of the subject 9, and determines that an abnormality has occurred in the measurement of the oxygen saturation by the saturation measurement unit 21 for body movement artifacts larger than a predetermined reference value. Then, for the measurement data group 211 during the period determined to be an abnormal state, it is detected as an outlier 221. FIG. 4 shows an example of the measurement data group 211 acquired by the saturation measurement unit 21. A plurality of sections in the measurement data group 211 may be detected as outliers 221 by the outlier detection unit 22.

[0017] The first data processing unit 23 calculates an abnormal value interval 232 that includes an adjacent time range 231 of a predetermined length that is temporally adjacent to the abnormal value 221 detected by the abnormal value detection unit 22, and generates a first data group 233 by removing the data from the abnormal value interval 232 from the measurement data group 211. In Figure 5, for the measurement data group 211 in which an abnormal value 221 is detected, the first data processing unit 23 divides the measurement data group 211 adjacent to both ends (the beginning and end in time) of each abnormal value 221 into adjacent time ranges 231 of a predetermined length, and combines the pair of adjacent time ranges 231 on both sides and the abnormal value 221 between them to form an abnormal value interval 232.

[0018] Figure 6 shows a magnified view of the area indicated by the dashed line in Figure 5. In Figure 6, the abnormal value interval 232 consists of the abnormal value 221 and the adjacent time ranges 231 on both sides of it. The length d of the adjacent time ranges 231 is a predetermined time, for example, 2 seconds. The adjacent time ranges 231 are not the abnormal value 221 that the abnormal value detection unit 22 determines to be abnormal, but by connecting the adjacent time ranges 231, the abnormal value interval 232 is extended temporally before and after the original abnormal value 221.

[0019] As described above, the first data processing unit 23 generates a first data group 233 (see Figure 7) by removing the data from the abnormal value interval 232 from the measurement data group 211. In Figure 7, in the first data group 233, a data gap 234 is formed after the outlier interval 232 is removed from the measurement data group 211. Such data gaps 234 occur frequently in a certain region 235 of the first data group 233.

[0020] The second data processing unit 24 calculates a reliability index 241 by convolution on the first data group 233 generated by the first data processing unit 23, and generates a second data group 243 (see Figure 9) by removing data from the first data group 233 in the low reliability interval 242 where the reliability index 241 is lower than a predetermined threshold.

[0021] As the reliability index 241, the ratio (0 to 1) of the data remaining after removing the outlier interval 232 from the measurement data group 211 to the data in the measurement data group 211 can be used. Convolution can be used when calculating the reliability index 241 at any point in time in the measurement data group 211. For example, let f(t) be the measurement data for oxygen saturation at time t. The measurement data f(t) is non-negative, and outliers are defined as 0. The convolution function g(n) used to determine which intervals of measurement data f(t) are outliers is as follows.

[0022]

number

[0023] The result of convolution of measurement data f(t) using such a convolution function g(t) is defined as the reliability index T(t) = f(t)·g(t). According to the convolution function g(t), the reliability index T(t) represents the satisfaction rate of the measurement data in the convolution interval, that is, how much data remains after removing abnormal data from the measurement data. The range of the reliability index T(t) is 0 to 1.

[0024] The predetermined threshold used to determine the reliability index 241 is set appropriately to include the distribution of the first data group 233 and the data missing portion 234, specifically the region 235 in the first data group 233 where data missing portions 234 occur frequently. For example, the threshold for the reliability index 241 is set to 0.7.

[0025] In Figure 7 mentioned above, data gaps 234 frequently occurred in some areas 235 of the first data group 233. In Figure 8, when the first data group 233 and the reliability index 241 are displayed on the same time axis, the threshold L = 0.7 is set. The low reliability interval 242 is identified as the region where the reliability index 241 is less than or equal to the threshold L = 0.7, and this region corresponds to the region 235 (see Figure 7) where the aforementioned data loss portion 234 occurs frequently. In Figure 9, in the second data group 243, a data gap 244 is formed after removing the low-reliability interval 242 from the first data group 233. In the portion that is not the low-reliability interval 242, the data gap 234 remains after removing the outlier interval 232 from the measurement data group 211. The time step for determining the low-reliability interval 242 from the reliability index 241 is preferably the same as the number of points in the convolution operation. If the number of convolution points is 180 (180 seconds) for data with a sampling interval of 1 second, the time step for evaluating the reliability index 241 should also be 180 seconds.

[0026] The third data processing unit 25 performs data interpolation on the second data group 243 generated by the second data processing unit 24, specifically on the abnormal value interval 232 (data missing section 234) and the low reliability interval 242 (data missing section 244), and adds interpolated data 251 to generate a third data group 252 (see Figure 10) with a predetermined time length. Any data interpolation method, such as linear interpolation or spline interpolation, can be used for data interpolation. If the duration of the data gaps 234 and 244 is longer than a predetermined threshold value, data interpolation may be stopped and the gaps may be excluded from the third data group 252. For the third data group, 252, it is desirable to ensure a continuous duration of 180 seconds, which is required for the analysis of the oxygen saturation reduction index, an indicator used in the diagnosis of sleep apnea syndrome.

[0027] The display control unit 26 displays various data obtained by the control device 20 on the display unit 30. The displayed content may include the third data group 252 obtained by the third data processing unit 25 and the reliability index 241 obtained by the second data processing unit 24. In addition, the measurement data group 211 that formed the basis of the measurement, or the first data group 233 and second data group 243 that are in the process of being processed may be displayed, and alerts based on these may also be displayed. Furthermore, the third data group 252 may be used to calculate the interval over a predetermined period of time during which the blood oxygen level decreased, or the number of times the blood oxygen level decreased, and the calculation results may be displayed on the display unit 30.

[0028] Figure 11 shows an example of the display screen 31 displayed on the display unit 30. The display screen 31 shows, along the time axis 32 displayed at the bottom, an oxygen saturation graph 33 showing the third data group 252 generated by the third data processing unit 25, a reliability index graph 34 showing the reliability index 241, and a threshold line 35 showing the threshold L. Of these, the oxygen saturation graph 33 and the reliability index graph 34 are displayed in a manner that is easily distinguishable from the vertical axis displays 36 on both sides, for example, by displaying different saturation, brightness, transparency, line type, etc., or by displaying a combination thereof. The threshold line 35 is displayed in a manner similar to the vertical axis display 36. The threshold line 35 may be displayed not only as a horizontal line added to the display of the reliability index graph 34, but also by other marks or shapes.

[0029] Furthermore, a portion of the oxygen saturation graph 33 displays an interpolated data display 331 showing interpolated data 251 for data gaps 234, and a low-reliability interval display 332 is shown for the low-reliability interval 242 (the range below the threshold L). The interpolated data display 331 and the low-reliability interval display 332 are displayed in a manner that is easily distinguishable from other parts of the oxygen saturation graph 33 (the range above the threshold L), for example, by displaying different saturation, brightness, transparency, line type, etc., or by a combination thereof. For the low-reliability interval display 332, data gaps 234 may be left uninterpolated and displayed in gray, which is less distinguishable than other parts of the oxygen saturation graph 33.

[0030] Figure 12 shows an overview of the processing performed by the pulse oximeter 1 of this embodiment. In the pulse oximeter 1, the processor of the control device 20 executes a program, which causes the following processes to be performed by the sensor unit 10 and the control device 20. In process S1, the sensor unit 10 irradiates the subject 9 with red light and infrared light and detects the red light and infrared light that have been transmitted through or reflected from the subject 9. In process S2, the saturation measurement unit 21 measures the blood oxygen saturation of the subject 9 from the detection signals of red light and infrared light, and records it as a group of measurement data 211 (see Figure 4). In process S3, the abnormal value detection unit 22 detects an abnormal value 221 that appears in the measurement data group 211 (see Figure 4). In processing S4, the first data processing unit 23 calculates an abnormal value interval 232 that includes an adjacent time range 231 of a predetermined length adjacent to the abnormal value 221, and generates a first data group 233 by removing the data from the abnormal value interval 232 from the measurement data group 211 (see Figures 5 and 6). In processing S5, the second data processing unit 24 calculates a reliability index 241 by convolution for the first data group 233 and generates a second data group 243 by removing data from the first data group 233 in the low reliability interval 242 where the reliability index 241 is lower than a predetermined threshold L (see Figure 9). In processing S6, the third data processing unit 25 performs data interpolation on the second data group 243 to remove the abnormal value interval 232 and the low reliability interval 242, and generates a third data group 252 with a predetermined time length (see Figure 10). In processing S6, the display control unit 26 displays the third data group 252, the threshold L, and the reliability index 241 on the display unit 30 (see Figure 11).

[0031] [Effects of this embodiment] The pulse oximeter 1 of this embodiment includes a red light sensor 12 that detects red light transmitted or reflected from a subject 9 when red light is irradiated onto the subject 9, an infrared light sensor 13 that detects infrared light transmitted or reflected from a subject 9 when infrared light is irradiated onto the subject 9, and a control device 20 that processes the detection signals from the red light sensor 12 and the infrared light sensor 13. The control device 20 includes a saturation measurement unit 21 that measures the blood oxygen saturation of a subject 9 from the detection signals of a red light sensor 12 and an infrared light sensor 13 and records it as a group of measurement data 211; an abnormal value detection unit 22 that detects abnormal values ​​221 that appear in the group of measurement data 211; and a first data group 233 that calculates an abnormal value interval 232 including an adjacent time range 231 of a predetermined length that is temporally adjacent to the abnormal value 221 detected by the abnormal value detection unit 22, and removes the data from the abnormal value interval 232 from the group of measurement data 211. The system is configured to include a data processing unit 23, a second data processing unit 24 that calculates a reliability index 241 by convolution on the first data group 233 and generates a second data group 243 by removing data from the first data group 233 in low-reliability intervals 242 where the reliability index 241 is lower than a predetermined threshold L, and a third data processing unit 25 that performs data interpolation processing on the second data group 243 for the removed abnormal value intervals 232 and low-reliability intervals 242 and generates a third data group 252 with a predetermined time length.

[0032] In such a pulse oximeter 1, a group of measurement data 211 of the blood oxygen saturation of the subject 9 is obtained by the red light sensor 12, the infrared light sensor 13, and the saturation measurement unit 21 of the control device 20. By detecting an abnormal value 221 in the measurement data group 211 using the abnormal value detection unit 22, measurement errors caused by the movement of the subject 9 can be eliminated, thereby improving measurement accuracy. In removing abnormal values ​​221 from the measurement data group 211, the first data processing unit 23 uses an abnormal value interval 232 that includes an adjacent time range 231 of a predetermined length that is temporally adjacent to the abnormal value 221. This allows for the removal of false values ​​that occur before and after the data detected as abnormal value 221, further improving measurement accuracy. Furthermore, in removing outliers 221 from the measurement data group 211, the second data processing unit 24 calculates a reliability index 241 by convolution on the first data group 233, and removes low-reliability intervals 242 where the reliability index 241 is lower than a predetermined threshold L from the measurement data group 211 along with the outlier intervals 232. This excludes intervals with few valid data from the measurement, further improving measurement accuracy. Through the above processing, the accuracy of measuring arterial blood oxygen saturation is improved, and by performing data interpolation processing by the third data processing unit 25, a continuous data set of sufficient length to determine the oxygen saturation decrease index is obtained.

[0033] The pulse oximeter 1 of this embodiment further has a display unit 30 that displays information obtained by the control device 20, allowing the user (the subject 9) or the examiner to recognize the test results. The display unit 30 can display not only the blood oxygen saturation measurement results from the control device 20, but also alerts based on the measurement results. These displays are shown in different formats based on the reliability index 241, improving the user's ability to identify the measurement results. Furthermore, the third data group 252 can be used to calculate the interval over a predetermined time period during which the blood oxygen level decreased, or the number of times the blood oxygen level decreased, and the calculation results can be displayed on the display unit 30.

[0034] The pulse oximeter 1 of this embodiment includes a red light sensor 12 that detects red light transmitted or reflected from a subject 9 when red light is irradiated onto the subject 9, an infrared light sensor 13 that detects infrared light transmitted or reflected from a subject 9 when infrared light is irradiated onto the subject 9, a control device 20 that processes the detection signals from the red light sensor 12 and the infrared light sensor 13, and a display unit 30 that displays the information obtained by the control device 20. The control device 20 measures the blood oxygen saturation of the subject 9 from the detection signals to generate a group of measurement data 211, and removes abnormal values ​​221 from the group of measurement data 211 to generate a group of oxygen saturation data. The system is configured to display the oxygen saturation data group (233) as the first data group, calculate a reliability index 241 for the oxygen saturation data group, and display the oxygen saturation data group (233) and the reliability index 241 on the display unit 30 on the same time axis. Furthermore, for the range in the oxygen saturation data group where the reliability index 241 exceeds a predetermined threshold L, data interpolation processing is performed on the missing data portion 234 that was removed from the measurement data group 211 as an abnormal value 221, and the threshold L is displayed on the display unit 30. In addition, the data interpolated portion (missing data portion 234) is displayed in a different display manner than the oxygen saturation data group (233).

[0035] In such a pulse oximeter 1, the blood oxygen saturation of the subject is measured by a red light sensor, an infrared light sensor, and a control device 20, and the measurement results can be displayed on the display unit. In the control device 20, abnormal values ​​221 are removed from the measurement data group 211 obtained from the red light sensor 12 and the infrared light sensor 13 to form an oxygen saturation data group (first data group 233), thereby eliminating measurement errors caused by the subject's body movements and improving measurement accuracy. Furthermore, by displaying the oxygen saturation data group together with its reliability index 241 on the same time axis, the user can recognize the reliability of the measurement results. For the oxygen saturation data group, data interpolation processing is performed on the data missing portion 234 removed from the measurement data group 211 to obtain continuous data (third data group 252) of sufficient length to determine the oxygen saturation decrease index. The display unit 30 displays the data interpolated portion (data missing portion 234) together with the threshold L of the reliability index 241 in a different display mode, thereby allowing the user to recognize the reliability of the measurement results in this respect as well.

[0036] [Other embodiments] Figure 13 shows another embodiment of the present disclosure. In Figure 13, the pulse oximeter 3 has a flat, disc-shaped case 4 and a belt 5, and can be worn on the user's wrist. A display unit 40 is formed on the surface of case 4, and the display unit 40 shows the current time 41, oxygen saturation level 42, reliability index 43, and alert 44. A control device 20A is housed inside case 4, and a sensor unit 10A is formed on the back side of case 4.

[0037] The sensor unit 10A, like the sensor unit 10 of the previously described embodiment, includes a red light sensor 12 and an infrared light sensor 13. The red light sensor 12 and the infrared light sensor 13 are positioned to be in close contact with the surface of the wrist when the pulse oximeter 3 is attached to the user's wrist with the belt 5, and this surface of the wrist becomes the subject 9. The control device 20A is configured in the same way as the control device 20 described above. It measures the blood oxygen saturation of the subject 9 from the detection signals of the red light sensor 12 and the infrared light sensor 13 to generate a group of measurement data 211, and calculates a reliability index 241 for the group of measurement data 211. The control device 20A, upon user operation, displays oxygen saturation data from the measurement data group 211 at the current time or any past time on the oxygen saturation display 42, and simultaneously displays the reliability index 241 at the same time on the reliability index display 43.

[0038] When the control device 20A displays the oxygen saturation indicator 42 and the reliability index indicator 43, it compares the reliability index 241 at the time of display with a predetermined threshold L and displays the indicator in different ways depending on whether it is above or below the threshold L. Specifically, when the reliability index 241 falls below the threshold L, the control device 20A displays a character or symbol on the alert display 44 indicating the possibility of an abnormal value due to body movement, and displays the reliability index display 43 in a different manner than when the reliability index 241 is above the threshold L, and displays the oxygen saturation display 42 in a different manner than when the reliability index 241 is above the threshold L. The differentiation of the display manner when the reliability index 241 is below the threshold L may be limited to just one of the three described above. Differences in display manners can include, for example, different saturation, brightness, transparency, line type, etc., or combinations thereof.

[0039] The pulse oximeter 3 of this embodiment includes a red light sensor 12 that detects red light transmitted or reflected from a subject 9 when red light is irradiated onto the subject 9, an infrared light sensor 13 that detects infrared light transmitted or reflected from a subject 9 when infrared light is irradiated onto the subject 9, a control device 20A that processes the detection signals from the red light sensor 12 and the infrared light sensor 13, and a display unit 40 that displays the information obtained by the control device 20A. The control device 20A measures the blood oxygen saturation of the subject 9 from the detection signals from the red light sensor 12 and the infrared light sensor 13 to generate a group of measurement data 211, calculates a reliability index 241 for the group of measurement data 211, and displays the group of measurement data 211, the reliability index 241 and the time on the display unit 40. The control device 20A is configured to display the range of the group of measurement data 211 that exceeds a predetermined threshold L and the range that falls below the threshold L in different display modes.

[0040] In such a pulse oximeter 3, the blood oxygen saturation of the subject 9 can be measured using the red light sensor 12, the infrared light sensor 13, and the control device 20A, and the measurement results can be displayed on the display unit 40. In the control device 20A, the measurement data group 211 obtained from the red light sensor 12 and the infrared light sensor 13 is displayed along with its reliability index 241 and time. In particular, the range of the measurement data group 211 that exceeds a predetermined threshold L and the range that falls below the threshold L are displayed in different display modes, thereby allowing the user to recognize the reliability of the measurement results.

[0041] [Differentiation] The present invention is not limited to the embodiments described above, and any modifications that can achieve the objectives of the present invention are included in the present invention. The pulse oximeter of the present invention is not limited to the reflective type described in the embodiments, but can also be used as a transmissive type. In the abnormal value detection unit 22, for determining abnormal values ​​221, in addition to detecting the subject's body movement using physical detection means such as an acceleration sensor 14 and determining the measured value of blood oxygen saturation at the time the body movement is detected as an abnormal value, other means may also be used, such as determining that the data in the blood oxygen saturation measurement data group 211 is an abnormal value.

[0042] In this specification, the pulse oximeter is described as a device that measures blood oxygen saturation. However, it goes without saying that the present invention can also be used with a blood oxygen wellness device that displays the measurement result as "blood oxygen level," rather than a device called a pulse oximeter. In this specification, the term pulse oximeter should be understood to include a blood oxygen wellness device.

[0043] [Summary of this disclosure] A pulse oximeter according to a first aspect of this disclosure includes: a red light sensor that detects the red light transmitted or reflected by irradiating a subject with red light; an infrared light sensor that detects the infrared light transmitted or reflected by irradiating a subject with infrared light; and a control device that processes the detection signals of the red light sensor and the infrared light sensor, wherein the control device includes: a saturation measurement unit that measures the blood oxygen saturation of the subject from the detection signals and records it as a group of measurement data; an abnormal value detection unit that detects abnormal values ​​appearing in the group of measurement data; and for the abnormal values ​​detected by the abnormal value detection unit The system includes: a first data processing unit that calculates an abnormal value interval including an adjacent time range of a predetermined length that is temporally adjacent, and generates a first data group by removing the data from the measurement data group. a second data processing unit that calculates a reliability index by convolution on the first data group and generates a second data group by removing the data from the first data group that is in a low reliability interval where the reliability index is lower than a predetermined threshold. a third data processing unit that performs data interpolation on the removed abnormal value interval and the low reliability interval on the second data group and generates a third data group with a predetermined time length.

[0044] In such a pulse oximeter, a set of measurement data on the blood oxygen saturation of the subject is obtained by a red light sensor, an infrared light sensor, and a saturation measurement unit of the control device. By detecting abnormal values ​​in the measurement data set using an abnormal value detection unit, measurement errors caused by the subject's body movements can be eliminated, thereby improving measurement accuracy. In removing outliers from the measurement data set, the first data processing unit uses an outlier interval that includes an adjacent time range of a predetermined length that is temporally adjacent to the outlier. This allows for the removal of false values ​​that occur before and after the data detected as an outlier, further improving measurement accuracy. Furthermore, in removing outliers from the measurement data set, the second data processing unit calculates a reliability index using convolution on the first data set. By removing low-reliability intervals where the reliability index is lower than a predetermined threshold, along with outlier intervals, from the measurement data set, intervals with insufficient valid data can be excluded from measurement, further improving measurement accuracy. Through the above processing, the accuracy of arterial blood oxygen saturation measurement is improved, and by performing data interpolation processing by the third data processing unit, a continuous data set of sufficient length to determine the oxygen saturation decrease index is obtained.

[0045] A pulse oximeter according to a first aspect of the present disclosure further includes a display unit for displaying information obtained by the control device, wherein the control device may use the third data group to calculate the interval over a predetermined time period during which the blood oxygen level decreased, or the number of times the blood oxygen level decreased, and display the calculation result on the display unit.

[0046] A pulse oximeter according to a second aspect of the present disclosure includes a red light sensor that detects the red light transmitted or reflected by irradiating a subject with red light, an infrared light sensor that detects the infrared light transmitted or reflected by irradiating a subject with infrared light, a control device that processes the detection signals from the red light sensor and the infrared light sensor, and a display unit that displays the information obtained by the control device. The control device measures the blood oxygen saturation of the subject from the detection signals to generate a group of measurement data, removes abnormal values ​​from the group of measurement data to obtain a group of oxygen saturation data, calculates a reliability index for the group of oxygen saturation data, displays the group of oxygen saturation data and the reliability index on the display unit on the same time axis, and performs data interpolation processing on the oxygen saturation data for the range in the group of oxygen saturation data where the reliability index exceeds a predetermined threshold, displays the threshold on the display unit, and further displays the interpolated portion in a different display mode from the oxygen saturation data group.

[0047] In such a pulse oximeter, a red light sensor, an infrared light sensor, and a control device measure the blood oxygen saturation of the subject, and the measurement results can be displayed on the display unit. In the control device, abnormal values ​​are removed from the measurement data sets obtained from the red light sensor and infrared light sensor to form an oxygen saturation data set, thereby eliminating measurement errors caused by the subject's body movement and improving measurement accuracy. Furthermore, by displaying the oxygen saturation data set along with its reliability index on the same time axis, the user can recognize the reliability of the measurement results. For the oxygen saturation data set, data interpolation processing is performed on the data missing portions removed from the measurement data set to obtain a continuous data set of sufficient length to calculate the oxygen saturation decrease index. By displaying the data interpolated portion along with the reliability index threshold in a different display mode on the display unit, the user can also recognize the reliability of the measurement results in this respect.

[0048] In a pulse oximeter according to a second aspect of this disclosure, the control device may calculate the interval over which the blood oxygen level has decreased over a predetermined period of time, or the number of times the blood oxygen level has decreased, and display the calculation result on the display unit.

[0049] In a pulse oximeter according to a second aspect of this disclosure, the threshold may be indicated by a mark or graphic added to the display of the reliability index.

[0050] In a pulse oximeter according to a second aspect of this disclosure, the range of measurement data that exceeds the threshold and the range that falls below the threshold may be displayed in different display modes.

[0051] The pulse oximeter according to a second aspect of the present disclosure, wherein the different display modes for the range above the threshold and the range below the threshold are any or a combination of saturation, brightness, and transparency.

[0052] In a pulse oximeter according to a second aspect of this disclosure, the different display modes of the data interpolated portion and the original group of measurement data may be saturation, brightness, transparency, or a combination thereof.

[0053] A pulse oximeter according to a third aspect of this disclosure includes a red light sensor that detects the red light transmitted or reflected by irradiating a subject with red light, an infrared light sensor that detects the infrared light transmitted or reflected by irradiating a subject with infrared light, a control device that processes the detection signals from the red light sensor and the infrared light sensor, and a display unit that displays the information obtained by the control device. The control device measures the blood oxygen saturation of the subject from the detection signals to generate a group of measurement data, calculates a reliability index for the group of measurement data, displays the group of measurement data, the reliability index, and the time on the display unit, and displays the range of the group of measurement data that exceeds a predetermined threshold and the range that falls below the threshold in different display modes.

[0054] In such a pulse oximeter, a red light sensor, an infrared light sensor, and a control device measure the blood oxygen saturation of the subject, and the measurement results can be displayed on the display unit. In the control device, the measurement data obtained from the red light sensor and infrared light sensor are displayed along with their reliability index and time. In particular, the range of measurement data that exceeds a predetermined threshold and the range that falls below the threshold are displayed in different ways, thereby allowing the user to recognize the reliability of the measurement results.

[0055] In a pulse oximeter according to a third aspect of this disclosure, when the reliability index falls below the threshold, letters or symbols indicating the possibility of abnormal values ​​due to body movement may be displayed; the display of the reliability index may be in a different manner than when the reliability index exceeds the threshold; or the display of the measurement data group may be in a different manner than when the reliability index exceeds the threshold, or a combination thereof. [Explanation of symbols]

[0056] 1,3…Pulse oximeter, 2,4…Case, 5…Belt, 9…Subject, 10,10A…Sensor unit, 11…Green light sensor, 110…Photodetector, 111…Green light source, 112…Red light source, 113…Infrared light source, 12…Red light sensor, 13…Infrared light sensor, 14…Accelerometer, 20,20A…Control device, 21…Saturation measurement unit, 211…Measurement data group, 22…Abnormal value detection unit, 221…Abnormal value, 23…First data processing unit, 231…Adjacent time range, 232…Abnormal value interval, 233…First data group, 234…Data missing section, 235…Region, 24…Second data processing unit, 241...Reliability index, 242...Low reliability interval, 243...Second data group, 244...Data missing section, 25...Third data processing unit, 251...Interpolated data, 252...Third data group, 26...Display control unit, 30...Display unit, 31...Display screen, 32...Time axis, 33...Oxygen saturation graph, 331...Interpolated data display, 332...Low reliability interval display, 34...Reliability index graph, 35...Threshold display line, 36...Vertical axis display, 40...Display unit, 41...Current time display, 42...Oxygen saturation display, 43...Reliability index display, 44...Alert display, f...Measurement data, g...Convolution function, L...Threshold, T...Reliability index.

Claims

1. The system includes a red light sensor that detects the red light transmitted or reflected from a subject after irradiating the subject with red light, an infrared light sensor that detects the infrared light transmitted or reflected from a subject after irradiating the subject with infrared light, and a control device that processes the detection signals from the red light sensor and the infrared light sensor. The control device is A saturation measurement unit measures the blood oxygen saturation of the subject from the detection signal and records it as a group of measurement data. An abnormal value detection unit for detecting abnormal values ​​that appear in the aforementioned measurement data group, A first data processing unit calculates an abnormal value interval that includes an adjacent time range of a predetermined length adjacent to the abnormal value detected by the abnormal value detection unit, and generates a first data group by removing the data of the abnormal value interval from the measurement data group. A second data processing unit calculates a reliability index by convolution for the first data group and generates a second data group by removing data in the low-reliability interval where the reliability index is lower than a predetermined threshold from the first data group. A pulse oximeter comprising: a third data processing unit that performs data interpolation processing on the second data group to remove the abnormal value interval and the low reliability interval, and generates a third data group with a predetermined time length.

2. Furthermore, it has a display unit that displays the information obtained by the control device, The pulse oximeter according to claim 1, wherein the control device uses the third data group to calculate the interval over which the blood oxygen level decreased or the number of times the blood oxygen level decreased over a predetermined period of time, and displays the calculation result on the display unit.

3. The system includes a red light sensor that detects the red light transmitted or reflected from a subject after irradiating the subject with red light, an infrared light sensor that detects the infrared light transmitted or reflected from a subject after irradiating the subject with infrared light, a control device that processes the detection signals from the red light sensor and the infrared light sensor, and a display unit that displays the information obtained by the control device. The control device measures the blood oxygen saturation of the subject from the detection signal to generate a group of measurement data, removes abnormal values ​​from the group of measurement data to obtain a group of oxygen saturation data, calculates a reliability index for the oxygen saturation data, and displays the oxygen saturation data and the reliability index on the display unit on the same time axis. A pulse oximeter that performs data interpolation on the data missing portion of the measurement data group that has been removed as an outlier for the range in which the reliability index exceeds a predetermined threshold among the oxygen saturation data group, displays the threshold on the display unit, and further displays the data interpolated portion in a display manner different from the oxygen saturation data group.

4. The pulse oximeter according to claim 3, wherein the control device calculates the interval over which the blood oxygen level decreased over a predetermined period of time, or the number of times the blood oxygen level decreased, and displays the calculation result on the display unit.

5. The pulse oximeter according to claim 3, wherein the threshold is displayed by a mark or figure added to the display of the reliability index.

6. The pulse oximeter according to claim 3, wherein the range of measurement data above the threshold and the range below the threshold are displayed in different display modes.

7. The pulse oximeter according to claim 6, wherein the different display modes for the range above the threshold and the range below the threshold are any or a combination of saturation, brightness, and transparency.

8. The pulse oximeter according to claim 3, wherein the different display mode of the interpolated portion of the data and the original group of measurement data is one or a combination of saturation, brightness, and transparency.

9. The system includes a red light sensor that detects the red light transmitted or reflected from a subject after irradiating the subject with red light, an infrared light sensor that detects the infrared light transmitted or reflected from a subject after irradiating the subject with infrared light, a control device that processes the detection signals from the red light sensor and the infrared light sensor, and a display unit that displays the information obtained by the control device. The control device measures the blood oxygen saturation of the subject from the detection signal to generate a group of measurement data, calculates a reliability index for the group of measurement data, and displays the group of measurement data, the reliability index, and the time on the display unit. A pulse oximeter that displays the range of measurement data above a predetermined threshold and the range below the threshold in different display modes.

10. The pulse oximeter according to claim 9, wherein when the reliability index falls below the threshold, letters or symbols indicating the possibility of an abnormal value due to body movement are displayed; the display of the reliability index is in a different manner than when the reliability index exceeds the threshold; or the display of the measurement data group is in a different manner than when the reliability index exceeds the threshold, or a combination thereof.

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