pulse oximeter

Abstract

To provide a pulse oximeter capable of measuring oxygen saturation with high accuracy. [Solution] The pulse oximeter includes a red light sensor that detects red light from a subject by irradiating the subject with red light, an infrared light sensor that detects infrared light from a subject by 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 includes an oxygen saturation measurement unit that generates a group of oxygen saturation data indicating the oxygen saturation of the subject based on the detection signals, and an abnormal value detection unit that detects abnormal values ​​in the oxygen saturation data group based on the subject's body movement based on at least one of the ratio of the red light signal intensity to the signal intensity of the amplitude signal of the detection signal of the red light sensor, and the ratio of the infrared light signal intensity to the signal intensity of the amplitude signal of the detection signal of the infrared light sensor.

Description

[Technical Field]

[0001] This invention relates to a pulse oximeter. [Background technology]

[0002] A pulse oximeter measures arterial blood oxygen saturation (SpO2) by shining red light and near-infrared light sources onto the finger and detecting the light that passes through the finger (see Patent Document 1). When performing tests for the oxygen saturation reduction index, which is an indicator of sleep apnea syndrome, the arterial blood oxygen saturation of the subject during sleep is measured using a pulse oximeter. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2004-337605 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] When measuring arterial blood oxygen saturation in subjects during sleep, there was a problem in that the accuracy of oxygen saturation measurement from the detection signal deteriorated because the subject's body movement caused disturbance signals (noise components) to be mixed into the detection signal based on the detection light in the pulse oximeter. [Means for solving the problem]

[0005] A pulse oximeter according to a first 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; and a control device that processes the detection signals of the red light sensor and the infrared light sensor, wherein the control device includes: an oxygen saturation measurement unit that generates a group of oxygen saturation data indicating the oxygen saturation of the subject from the detection signals of the red light sensor and the infrared light sensor; and an abnormal value detection unit that detects abnormal values ​​of the oxygen saturation data based on the body movement of the subject based on at least one of a red light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the red light sensor to the signal intensity of the detection signal, and an infrared light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the infrared light sensor to the signal intensity of the detection signal.

[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 information obtained by the control device. The control device generates a group of oxygen saturation data indicating the oxygen saturation of the subject from the detection signals from the red light sensor and the infrared light sensor, calculates an index value based on at least one of a red light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the red light sensor to the signal intensity of the detection signal, and an infrared light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the infrared light sensor to the signal intensity of the detection signal, and displays a graph on the display unit showing the oxygen saturation data group and the index value on the same time axis.

[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, wherein the control device calculates the oxygen saturation of the subject from the detection signals from the red light sensor and the infrared light sensor, and the red light sensor outputs The system calculates an index value from the analysis results of at least one of the time variation analyses of the red light signal intensity ratio, which shows the ratio of the amplitude of the vibration component in the detected signal to the signal intensity of the detected signal, and the infrared light signal intensity ratio, which shows the ratio of the amplitude of the vibration component in the detected signal output by the infrared light sensor to the signal intensity of the detected signal. The system then displays the oxygen saturation and the analysis results on the display unit, and displays the oxygen saturation or the analysis results in different display formats depending on whether the analysis results are above a predetermined threshold or below the threshold. [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 diagram showing an example of a detected signal. [Figure 5] A figure showing the absorption spectra of oxyhemoglobin and deoxyhemoglobin. [Figure 6] A figure showing the oxygen saturation data set, the red light signal intensity ratio, and the infrared light signal intensity ratio in the above embodiment on the same time axis. [Figure 7] A diagram illustrating a method for detecting sudden peak points using a moving section. [Figure 8]A figure showing the oxygen saturation data set, the coefficient of variation of the red light signal intensity ratio, and the coefficient of variation of the infrared light signal intensity ratio in the above embodiment, all on the same time axis. [Figure 9] This figure shows the process by which the data processing unit in the above embodiment removes abnormal values. [Figure 10] A diagram showing the interpolation process by the data processing unit in the above embodiment. [Figure 11] A schematic diagram showing an example of the display screen in the above embodiment. [Figure 12] A schematic diagram showing another example of the display screen in the above embodiment. [Figure 13] A flowchart illustrating the operation of the pulse oximeter in the above embodiment. [Figure 14] 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. Figure 1 is a schematic diagram showing a pulse oximeter according to one embodiment of the present disclosure, and Figure 2 is a schematic diagram showing the pulse oximeter in use according to the present embodiment. 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. Preferably, the emission wavelength of the green light source 111 is 500nm to 600nm, the emission wavelength of the red light source 112 is 600nm to 800nm, and the emission wavelength of the infrared light source 113 is 800nm ​​to 1000nm. The photodetector 110 is, for example, a silicon photodiode. The green light source 111, red light source 112, infrared light source 113, and photodetector 110 of the sensor unit 10 are covered on their surfaces with a cover (not shown) made of a transparent resin molded plate such as acrylic or polycarbonate.

[0011] In the sensor unit 10, the green light source 111, the red light source 112, and the infrared light source 113 each emit light sequentially 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 signals from the photodetector 110 as a green light detection signal, a red light detection signal, and an infrared light detection signal from the light 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.

[0012] Figure 3 is a block diagram showing the configuration of the control device 20 and the functional configuration of the processor. The control device 20 is composed of a small computer system and includes a memory for storing various data, and a processor that executes programs stored in the memory to realize the intended function (see Figure 3). Case 2 houses the battery that powers the sensor unit 10 and the control device 20, as well as the input / output terminals of the control device 20 (not shown).

[0013] The display unit 30 is connected to the control device 20 by wired or wireless signaling means and can display measurement results and other information from the control device 20. The display unit 30 can be, for example, a general-purpose image display panel or a mobile information terminal such as a smartphone.

[0014] As shown in Figure 3, the control device 20 functions as a signal acquisition unit 21, a saturation measurement unit 22, an abnormal value detection unit 23, a data processing unit 24, and a display control unit 25 when the processor executes a program.

[0015] The signal acquisition unit 21 controls the green light sensor 11, red light sensor 12, and infrared light sensor 13 of the sensor unit 10 connected to the control device 20, and acquires (receives) detection signals. Furthermore, the signal acquisition unit 21 calculates the signal intensity ratio based on the received detection signals. The signal intensity of the detection signals from each color sensor differs for each color of light. Therefore, the signal acquisition unit 21 calculates the signal intensity ratio from the signal intensity of each color of light so that highly accurate processing is possible in the measurement of blood oxygen saturation (SpO2) by the saturation measurement unit 22 (described later) and in the detection of abnormal values ​​by the abnormal value detection unit 23 (described later). In the following explanation, arterial blood oxygen saturation may be simply referred to as oxygen saturation.

[0016] Figure 4 shows an example of a detection signal. For example, by sampling the detection signal from one sensor at a predetermined sampling period, a pulse wave signal like the one shown in Figure 4 can be obtained. Here, the amplitude intensity of the detection signal (pulse wave signal) is denoted as AC, and the signal intensity as DC. The detection signal for each color of light is a pulse wave in which an oscillation component is superimposed on a DC component. The amplitude intensity AC is detected from the amplitude of the oscillation component, and the DC intensity DC is detected at the center of the amplitude. Once the amplitude intensity AC and DC intensity DC are obtained, the pulse wave signal intensity ratio of the detection signal can be obtained by the ratio of amplitude intensity AC to DC intensity DC (signal intensity ratio PI = AC / DC). Here, the signal intensity ratio for red light (red light signal intensity ratio PI) red ), infrared light signal intensity ratio (infrared light signal intensity ratio PI) ir ), and the green light signal intensity ratio (green light signal intensity ratio PI) grn ) is calculated using the following equations (1) to (3). AC red This is the amplitude intensity of the detection signal from the red light sensor 12, and DC red This is the signal intensity of the detection signal from the red light sensor 12. AC ir This is the amplitude intensity of the detection signal from the infrared light sensor 13, and DC ir This is the signal intensity of the detection signal from the infrared light sensor 13. AC grn This is the amplitude intensity of the detection signal from the green light sensor 11, and DCgrn is the signal intensity of the detection signal from the green light sensor 11.

[0017] [Number]

[0018] The saturation measurement unit 22 calculates the arterial blood oxygen saturation of the subject 9 based on the red light signal intensity ratio PIred and the infrared light signal intensity ratio PIir, and records it in the memory as the oxygen saturation data group 300. FIG. 5 is a diagram showing the absorption spectra of oxyhemoglobin and reduced hemoglobin. The detection signals of the green light sensor 11, the red light sensor 12, and the infrared light sensor 13 are photoplethysmogram signals based on the green light, red light, and infrared light that have passed through the subcutaneous tissue of the subject 9. The absorption amounts of each color light to oxyhemoglobin and the absorption amount to reduced hemoglobin are different. That is, for green light, the light absorption amounts for both oxyhemoglobin and reduced hemoglobin are large, and for infrared light, the light absorption amounts for both oxyhemoglobin and reduced hemoglobin are extremely small. On the other hand, for red light, a large difference occurs between the light absorption amount to oxyhemoglobin and the light absorption amount to reduced hemoglobin.

[0019] Therefore, the saturation measurement unit 22 can accurately measure the oxygen saturation based on the difference in the light absorption amounts of red light and infrared light from the detection signals (photoplethysmogram signals) of the red light sensor 12 and the infrared light sensor 13. Specifically, the red light signal intensity ratio PI red calculated from the detection signal of red light and the infrared light signal intensity ratio PI ir calculated from the detection signal of infrared light are used to calculate the red-infrared signal ratio R. Also, mapping data showing the relationship between the red-infrared signal ratio R and the oxygen saturation is stored in the memory in advance. Then, the saturation measurement unit 22 calculates the oxygen saturation based on the red-infrared signal ratio R and the mapping data, and calculates the oxygen saturation corresponding to each detection signal obtained at a predetermined sampling period to obtain the oxygen saturation data group 300.

[0020] Figure 5 shows the absorption spectra of oxyhemoglobin and deoxyhemoglobin. The detection signals from the green light sensor 11, the red light sensor 12, and the infrared light sensor 13 are photoplethysmography signals based on green light, red light, and infrared light transmitted through the subcutaneous tissue of the subject 9, and the amount of absorption by oxyhemoglobin and the amount of absorption by deoxyhemoglobin differ for each color. In other words, for green light, the amount of light absorption by both oxyhemoglobin and deoxyhemoglobin is large, while for infrared light, the amount of light absorption by both oxyhemoglobin and deoxyhemoglobin is very small. On the other hand, for red light, there is a large difference between the amount of light absorption by oxyhemoglobin and the amount of light absorption by deoxyhemoglobin. Therefore, the saturation measurement unit 22 can accurately measure oxygen saturation based on the difference in light absorption between red light and infrared light from the detection signals (photoelectric pulse wave signals) of the red light sensor 12 and the infrared light sensor 13. Specifically, it calculates the red-infrared signal ratio R between the detection signal of red light and the detection signal of infrared light. In addition, it stores mapping data in memory that shows the relationship between the red-infrared signal ratio R and oxygen saturation. The saturation measurement unit 22 then calculates the oxygen saturation based on the red-infrared signal ratio R and the mapping data, and obtains an oxygen saturation data group 300 by calculating the oxygen saturation corresponding to each detection signal acquired at a predetermined sampling period.

[0021] The saturation measurement unit 22 measures the red light signal intensity ratio PI red and infrared light signal intensity ratio PI ir Using these, the red-infrared signal ratio R is calculated by the following equation (4).

[0022]

number

[0023] The abnormal value detection unit 23 detects motion artifacts (abnormal values ​​301) caused by the body movements of the subject 9 that appear in the oxygen saturation data group 300. The abnormal value detection unit 23 detects motion artifacts by determining the red light signal intensity ratio PI, which is calculated using the above equations (1) and (2). red and infrared light signal intensity ratio PI ir Body motion artifacts are detected using an index value 231 based on at least one of the following.

[0024] Figure 6 shows the oxygen saturation data group 300 and the red light signal intensity ratio PI. red And, the infrared light signal intensity ratio PI ir This figure shows the two on the same time axis. In other words, the red light signal intensity ratio PI in Figure 6. red The curve shown represents the red light signal intensity ratio PI, which is calculated based on the detection signal obtained from the red light sensor 12 acquired at a predetermined sampling period. red The red light signal intensity ratio PI shows the temporal change of red This is the data set. Also, the infrared light signal intensity ratio PI in Figure 6. ir The curve shown is the infrared light signal intensity ratio PI calculated based on the detection signal obtained from the infrared light sensor 13 acquired at a predetermined sampling period. ir The infrared light signal intensity ratio PI shows the temporal change of [the signal intensity ratio]. ir This is a set of data.

[0025] In Figure 6, the red light signal intensity ratio PI is shown at times T1 to T4. red and infrared light signal intensity ratio PI ir At least one of the following is the red light signal intensity ratio PI of the other time zone. red and infrared light signal intensity ratio PI ir It can be seen that the peak value fluctuates significantly compared to [the previous example]. The red light signal intensity ratio PI at these times T1 to T4 is [the current value]. red and infrared light signal intensity ratio PI ir The change is not due to a sudden change in blood flow, but rather to a disturbance in the detection signal caused by body movement. In particular, in a reflective pulse oximeter 1 that emits red light, infrared light, and green light from the sensor unit 10 and receives the light reflected inside the body of the subject 9, the red light signal intensity ratio PI red and infrared light signal intensity ratio PI irThe red light signal intensity ratio PI becomes very small. Therefore, even slight movements such as subject 9 turning over in bed can reduce the red light signal intensity ratio PI. red or infrared light signal intensity ratio PI ir Sudden peak points (artifacts) may be introduced. Note that in Figure 6, the green light signal intensity ratio PI is... grn The diagram is omitted, but the green light signal intensity ratio PI grn The same applies to this matter.

[0026] Furthermore, as shown in Figure 6, the red light signal intensity ratio PI red or infrared light signal intensity ratio PI ir If a sudden peak point 401 is included, oxygen saturation will also fluctuate suddenly. This is not due to a change in blood oxygen saturation, but rather to the inclusion of sudden body movement artifacts. In this disclosure, the sudden peak point 401 refers to the red light signal intensity ratio PI included in a predetermined period. red or infrared light signal intensity ratio PI ir This refers to a peak point where, among multiple peak points, the difference between its peak value and the peak value of other peak points is greater than or equal to a predetermined value, and the number of such peak points during the predetermined period is less than or equal to a predetermined number set in advance. For example, in the example in Figure 6, the predetermined period is defined as the time required to determine sleep apnea syndrome (e.g., 180 seconds), and during that predetermined period, if there are two or fewer peak points whose peak value is greater than or equal to the predetermined value of other peak points, then a peak point whose peak value is greater than or equal to the predetermined value of other peak points is defined as a sudden peak point.

[0027] Two methods can be used by the anomaly detection unit 23 to detect motion artifacts: The first method calculates the signal intensity ratio PI (red light signal intensity ratio PI) from the detection signals of each color acquired at a predetermined sampling period. red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn This method calculates the sudden peak point 401 itself by using at least one of the following as the index value 231. In this method, the anomaly detection unit 23 uses the signal intensity ratio PI (red light signal intensity ratio PI) as the index value 231.red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn The second derivative curve of ) is calculated, and its zero-crossing points are determined. This allows for the detection of peak points included in the signal intensity ratio PI, and the peak value of each peak point can be calculated. Therefore, the average peak value of the peak points over a predetermined period can be calculated, and peak points with peak values ​​greater than or equal to a predetermined value relative to the average peak value can be detected as sudden peak points 401.

[0028] Alternatively, the signal intensity ratio PI (red light signal intensity ratio PI) red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn ) A predetermined period (hereinafter referred to as the "movement period") may be set, and the maximum value of the signal intensity ratio PI during the said movement period may be detected as a sudden peak point 401.

[0029] Figure 7 illustrates a method for detecting sudden peak points 401 using a moving section. The abnormal value detection unit 23 detects a certain measurement time as the time of interest T i The analysis range ΔT (sec) is set before and after the time of interest T to form a movement section 410, and the maximum value m of the signal intensity ratio PI within the movement section 410 and the time Tm at which the maximum value m is obtained are calculated. Then, the anomaly detection unit 23 determines the time of interest T i The data was sent sequentially (to move the travel section, at the time of focus T). i When (the value is changed), if the maximum value m and the time Tm at which the maximum value m is taken do not change within a predetermined range, then the maximum value m is defined as the sudden peak point 401. This predetermined range is, for example, (the time Tm at which the value is taken). i The time length of the analysis range is 2 × ΔT. Alternatively, the interval may be from (Tm - ΔT) ± ΔT to (Tm + ΔT) ± ΔT.

[0030] In the first method, the anomaly detection unit 23 detects the data (oxygen saturation) from the oxygen saturation data group 300 corresponding to the time Tm at which the detected sudden peak point 401 is obtained as an anomaly value 301. At this time, the anomaly detection unit 23 detects the red light signal intensity ratio PI red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn It is preferable to use one of the following as the index value 231, and to detect an abnormal value 301 corresponding to the peak point 401 when a sudden peak point 401 is obtained. The abnormal value detection unit 23 is the red light signal intensity ratio PI red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn If a sudden peak point 401 is obtained at the same location for any two or all of the signal intensity ratios PI, an abnormal value corresponding to that peak point 401 may be detected.

[0031] Furthermore, the second method involves the signal intensity ratio PI (red light signal intensity ratio PI). red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn This method uses the results of the time variation analysis of ) as the index value 231. For example, in time variation analysis, a predetermined time of interest T i An analysis range is set with a duration of Δt (sec) before and after the point, and the variance v, standard deviation s, or coefficient of variation cv of the signal intensity ratio PI of n points included in the analysis range is calculated as shown in equations (5) to (7) below. Note that the Δt (sec) used to set this analysis range may be the same length as the above-mentioned movement interval 410, in which case Δt = ΔT.

[0032]

number

[0033] Note that in equations (5) to (7) above, x i This is the signal intensity ratio PI (red light signal intensity ratio PI) included in the analysis range. red , infrared light signal intensity ratio PIir , and the green light signal intensity ratio PI grn ) and x-bar is the average value of the signal intensity ratio PI included in the analysis range. When using the second method, the anomaly detection unit 23 calculates either the variance v, standard deviation s, or coefficient of variation cv of the signal intensity ratio PI, uses one of the calculated variance v, standard deviation s, or coefficient of variation cv as the index value 231, and determines whether the index value 231 exceeds a predetermined threshold. If any of the variance v, standard deviation s, or coefficient of variation cv exceeds a predetermined threshold within the analysis range, it means that there is a large variation in the signal intensity ratio PI within that analysis range, indicating the presence of a sudden peak point 401. Note that the threshold when using variance v, the threshold when using standard deviation s, and the threshold when using the coefficient of variation cv are different, respectively. In particular, the coefficient of variation cv, as shown in equation (7), is a value obtained by normalizing the standard deviation s by the mean, and can be used as a constant detection index that is independent of differences between individual pulse oximeters 1 and differences in measurement sites, making it suitable.

[0034] Figure 8 shows the oxygen saturation data group 300 and the red light signal intensity ratio PI. red Coefficient of variation PICV red And, the infrared light signal intensity ratio PI ir Coefficient of variation PICV ir This is a diagram showing and on the same time axis. Even when using the second method, as shown in Figure 8, it is possible to detect motion artifacts at the same time positions (T1-T4) as in Figure 6. Note that in Figure 8, the green light signal intensity ratio PI grn Coefficient of variation PICV grn The diagram is omitted, but the green light signal intensity ratio PI grn Coefficient of variation PICV grn The same applies to this matter.

[0035] In the second method, the anomaly detection unit 23 detects data (oxygen saturation) from the oxygen saturation data group 300 that corresponds to the range in which the analysis result, which is the index value 231, exceeds the threshold as an anomaly value 301. In this case, similar to the first method, the abnormal value detection unit 23 determines the red light signal intensity ratio PI red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn If any of the analysis results of each time variation analysis exceed a threshold, it may be determined that there is an abnormal value 301. Alternatively, the abnormal value detection unit 23 may determine that the red light signal intensity ratio PI red , infrared light signal intensity ratio PI ir , and the green light signal intensity ratio PI grn If any two or all of the analysis results from each of the time variation analyses exceed a threshold, it may be determined that there is an outlier.

[0036] Furthermore, the abnormal value detection unit 23 estimates the period during which the subject 9 is moving (body movement period L). For example, when detecting an abnormal value 301 using the first method, the oxygen saturation at one point corresponding to the sudden peak point 401 is detected as the abnormal value 301. In this case, the abnormal value detection unit 23 detects the abnormal value 301 at time T i The period of body movement L is estimated to include a predetermined time Δτ before and after the time centered on the point. Alternatively, the data processing unit 24 estimates the time T when the abnormal value 301 was detected. i The period L of physical movement may include the range in which oxygen saturation is below a predetermined value.

[0037] On the other hand, the second method calculates the results of a temporal variation analysis indicating whether or not a sudden peak point 401 is included within the analysis range (whether or not an anomaly value 301 exists within the analysis range). Therefore, if a sudden peak point is included within the analysis range, the analysis results will exceed a threshold within a predetermined time range, as shown in Figure 8. In this case, the anomaly detection unit 23 may estimate the entire range in which the analysis results exceed the threshold as the motion period L.

[0038] The data processing unit 24 generates an anomaly-removed data group 310 by deleting the anomaly value 301 (oxygen saturation) detected by the anomaly detection unit 23 and the data (oxygen saturation) included in the body movement period L from the oxygen saturation data group 300. Furthermore, the data processing unit 24 connects the deleted portions with interpolated data 321 to create a corrected data set 320. Any data interpolation method, such as linear interpolation or spline interpolation, can be used for the data interpolation process.

[0039] Figures 9 and 10 show the data processing unit 24's process for deleting or interpolating abnormal values ​​301. For example, in Figure 9, the data processing unit 24 deletes data for a specific interval (body movement period L) in the oxygen saturation data group 300 based on the abnormal values ​​detected by the abnormal value detection unit 23, thereby creating the abnormality removal data group 310. In Figure 10, the data processing unit 24 interpolates the intervals in the oxygen saturation data group 300 where data has been deleted using interpolated data 321, and the oxygen saturation data group 300 interpolated with the interpolated data 321 is designated as the corrected data group 320.

[0040] The display control unit 25 displays various data calculated by the control device 20 on the display unit 30. The displayed content may include oxygen saturation data group 300, anomaly removal data group 310, correction data group 320, and an index value 231 for detecting anomalies 301. Additionally, alerts based on the oxygen saturation data group 300 and index value 231, or the estimated body movement period L based on the anomaly 301, may be displayed. Furthermore, based on the index value 231, the system may calculate the interval over a predetermined time period during which oxygen saturation decreased, or the number of times oxygen saturation decreased, and display the calculation results on the display unit 30.

[0041] Figure 11 shows an example of a display screen 31 displayed on the display unit 30 of this embodiment. For example, the display screen 31 shown in Figure 11 includes an oxygen saturation graph 51, an index value graph 52, a peak point image 53, and a body motion display unit 54 along the time axis 32 displayed at the bottom. The oxygen saturation graph 51 is a graph showing the oxygen saturation data group 300 calculated by the saturation measurement unit 22, or the abnormal removal data group 310 or the corrected data group 320 calculated by the data processing unit 24. A switching icon that allows switching between the data groups displayed in the oxygen saturation graph 51 may be displayed on the display screen 31. In this case, when the user selects a switching icon, the display control unit 25 switches and displays the oxygen saturation data group 300, the abnormal removal data group 310, and the corrected data group 320. Figure 11 is an example showing oxygen saturation graph 51 displaying oxygen saturation data group 300.

[0042] The index value graph 52 is a graph showing the index value 231 used when the anomaly detection unit 23 detects an anomaly. In the example in Figure 11, an example is shown where an anomaly is detected by the first method, and the index value 231 is the red light signal intensity ratio PI. red , and infrared light signal intensity ratio PI ir This is displayed in the indicator value graph 52. The indicator value graph 52 is displayed in a different format from the oxygen saturation graph 51 so that it can be distinguished from the oxygen saturation graph 51. For example, it is displayed in a different color, line type, or line width than the oxygen saturation graph 51.

[0043] The peak point image 53 shows the sudden peak point 401 in the index value and the abnormal value of oxygen saturation corresponding to the peak point 401, which are detected by the anomaly value detection unit 23 using the first method. Preferably, the peak point image 53 is displayed using a different color, line type, etc., from the oxygen saturation graph 51 and the index value graph 52, for example, so that its position on the oxygen saturation graph 51 and the index value graph 52 is clearly identifiable. For example, in the example in Figure 11, the peak point image 53 is displayed by overlaying a circular image onto the oxygen saturation graph 51 and the index value graph 52.

[0044] The motion display unit 54 shows the range of the motion period L detected by the abnormal value detection unit 23. The motion display unit 54 displays the period during which motion is estimated to have occurred on the time axis 32 in a different display format from the oxygen saturation graph 51, the index value graph 52, and the peak point image 53. In addition, vertical axis displays 33 showing the values ​​of the oxygen saturation graph 51 and the index value graph 52 are displayed on both sides of the display screen 31.

[0045] Figure 12 shows another example of the display screen 31A displayed on the display unit 30 of this embodiment. Figure 11 above is an example of the display screen 31 when the abnormal value detection unit 23 detects an abnormal value 301 using the first method. In contrast, Figure 12 is an example of the display screen 31A when the abnormal value detection unit 23 detects an abnormal value 301 using the second method. For example, the display screen 31A shown in Figure 12 includes an oxygen saturation graph 51, an index value graph 52A, a threshold display unit 55, and a body movement display unit 54 along the time axis 32 displayed at the bottom. Also, on both sides of the display screen 31A, similar to Figure 11, vertical axis displays 33 showing the values ​​of the oxygen saturation graph 51 and the index value graph 52 are displayed.

[0046] The oxygen saturation graph 51 is similar to the display screen 31 shown in Figure 11, and is a graph showing the oxygen saturation data group 300, or the abnormal removal data group 310, or the corrected data group 320. Also, as in the case of Figure 11, a switching icon or similar that allows switching between the data groups displayed in the oxygen saturation graph 51 may be displayed on the display screen 31. Figure 12 shows an example where the abnormality removal data group 310 is displayed as an oxygen saturation graph 51.

[0047] The index value graph 52A is a graph showing the index value 231 used when the abnormal value detection unit 23 detects an abnormal value. The example in Figure 12 is the display screen 31A when the abnormal value 301 is detected by the second method as described above, and the index value graph 52A is shown as the index value 231, and the signal intensity ratio PI (red light signal intensity ratio PI) is shown as the signal intensity ratio PI red, Infrared light signal intensity ratio PI ir , Green light signal intensity ratio PI grn ) displays the analysis result of the time variation analysis. For example, in FIG. 12, as the analysis result, the coefficient of variation cv of the signal intensity ratio PI is used, and for the red light signal intensity ratio PI red coefficient of variation PICV red , infrared light signal intensity ratio PI ir coefficient of variation PICV ir , and the coefficient of variation PICV of the green light signal intensity ratio PI grn are displayed. The index value graph 52A is displayed in a different display form from the oxygen saturation graph 51 so as to be distinguishable from the oxygen saturation graph 51. For example, it is displayed in a different color, line type, or line width from the oxygen saturation graph 51.

[0048] The threshold display unit 55 indicates the threshold of the analysis result (in this example, the coefficient of variation cv) of the time variation analysis by the outlier detection unit 23. Note that the threshold display unit 55 is not limited to a horizontal straight line as shown in FIG. 12 and may be displayed by other marks or figures.

[0049] The body movement display unit 54 is the same as in FIG. 11 and indicates the range of the body movement period L detected by the outlier detection unit 23.

[0050] [[ID=2,7]] [Operation of Pulse Oximeter] FIG. 13 shows an outline of the processing executed by the pulse oximeter 1 of this embodiment. In the pulse oximeter 1, by the processor of the control device 20 executing a program, the following processing is executed by each part of the sensor unit 10 and the control device 20. First, the signal acquisition unit 21 controls the sensor unit 10 to irradiate the subject 9 with green light, red light, and infrared light, and detect the green light, red light, and infrared light transmitted or reflected by the subject 9. Thereby, the signal acquisition unit 21 acquires detection signals of each color from the sensor unit 10 (step S1). Also, the signal acquisition unit 21 calculates the signal intensity ratio PI of each color light from the acquired detection signals of each color light (red light signal intensity ratio PI red , infrared light signal intensity ratio PI​​ir , the green light signal intensity ratio PI grn ) is calculated (step S2). Then, the saturation measurement unit 22 measures the red light signal intensity ratio PI red and the infrared light signal intensity ratio PI ir and uses the red-infrared signal ratio R recorded in the memory to measure the oxygen saturation of the subject 9 and records it as the oxygen saturation data group 300 (step S3).

[0051] Next, the outlier detection unit 23 calculates an index value 231 for detecting outliers (step S4). Here, when the outlier detection unit 23 detects outliers by the first method, the signal intensity ratio PI of each color light from the detection signals of each color (PI red , PI ir , PI grn ) is calculated as the index value 231. Also, when the outlier detection unit 23 detects outliers by the second method, the analysis result of the time variation analysis of the signal intensity ratio PI of each color light (PI red , PI ir , PI grn ) (for example, the coefficient of variation cv (PICV red , PICV ir , PICV grn )) is calculated as the index value 231. Note that the method for detecting outliers by the outlier detection unit 23 may be appropriately selected by the user, and the index value 231 may be calculated according to the user's selection.

[0052] Next, the outlier detection unit 23 detects outliers 301 appearing in the oxygen saturation data group 300 based on the calculated index value 231 (step S5). The method for detecting outliers 301 is as described above, and the first method or the second method is used. As described above, the configuration may be such that the user can select either the first method or the second method. Also, in step S5, the outlier detection unit 23 estimates the body movement period L based on the outliers 301 (step S6).

[0053] Next, the data processing unit 24 removes abnormal values ​​301 and data for the body movement period L from the oxygen saturation data group 300 to generate anomaly-removed data group 310. Furthermore, it performs interpolation on the removed data to generate interpolated data 321 and then generates corrected data group 320 (step S7).

[0054] Subsequently, the display control unit 25 displays the oxygen saturation graph 51 based on the oxygen saturation data group 300 or the abnormality removal data group 310 or the correction data group 320, the index value graph 52 based on the index value, etc., on the display unit 30 as shown in Figures 11 and 12 (step S8).

[0055] By the way, in the pulse oximeter 1 of this embodiment, whether or not it is functioning normally can be confirmed by the following operation. A film or sheet capable of suppressing the transmission of light at the inspection wavelengths of the green light sensor 11, the red light sensor 12, and the infrared light sensor 13 is prepared and placed between the sensor part 10 of the pulse oximeter 1 and the subject 9 for measurement. Pulse oximeter 1 shows the red light signal intensity ratio PI red , or the red light signal intensity ratio PI red When detecting the outlier 301 using the analysis results (variance v, standard deviation s, coefficient of variation cv) of the time variation analysis, the function of detecting motion artifacts is impaired when a film that suppresses red light is inserted, but the function is restored by removing the film. Pulse oximeter 1 is the infrared light signal intensity ratio PI ir , or infrared light signal intensity ratio PI ir When detecting the anomaly value 301 using the analysis results of the time variation analysis, the function of detecting motion artifacts is impaired when a film that suppresses infrared light is inserted, but the function is restored by removing the film. Pulse oximeter 1 is the green light signal intensity ratio PI grn , or the green light signal intensity ratio PI grnWhen detecting the anomaly value 301 using the analysis results of the time variation analysis, the function of detecting motion artifacts when a film that suppresses green light is inserted is impaired, but the function is restored by removing the film. In this way, the function of the pulse oximeter 1 can be determined by blocking the inspection light.

[0056] [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 22 that measures the 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 as an oxygen saturation data group 300, and an abnormal value detection unit 23 that detects abnormal values ​​301 caused by the movement of the subject 9 that appear in the oxygen saturation data group 300 based on the signal intensity ratio PI.

[0057] Such pulse oximeters use at least the red light signal intensity ratio PI to calculate oxygen saturation. red and infrared light signal intensity ratio PI ir Using at least one of these methods, abnormal oxygen saturation values ​​301 based on the body movements of the subject 9 can be detected, and highly accurate oxygen saturation measurement processing can be performed by excluding the abnormal values ​​301. Furthermore, abnormal values ​​301 based on body movement can be detected without using other sensors such as an accelerometer. In other words, since abnormal values ​​301 based on body movement are detected using the detection signals of the red light sensor 12 and infrared light sensor 13 used to measure oxygen saturation, there is no need to incorporate a separate configuration for detecting body movement such as an accelerometer, and the configuration of the pulse oximeter 1 can be simplified. In addition, when using an accelerometer that directly detects the physical movement of the subject 9, it may not be possible to detect minute movements of the subject 9. However, when detecting body movement using an index value 231 based on at least one of the signal intensity ratios PI calculated from the detection signals of each color of light, even abnormal values ​​301 due to minute body movements of the subject 9 can be detected with high accuracy.

[0058] In the pulse oximeter 1 of this embodiment, when the abnormal value detection unit 23 detects an abnormal value 301 using the first method, the abnormal value detection unit 23 detects the oxygen saturation at the time the sudden peak point 401 was obtained as an abnormal value 301 when a sudden peak point 401 is detected in which the difference between it and other peak values ​​included within a predetermined period is greater than or equal to a predetermined value in at least one of the multiple peak values ​​included in the signal intensity ratio PI calculated from the detection signals of each color light. When the subject 9 moves, the detection signal is disturbed, and as a result, a sudden peak point 401 appears in one of the signal intensity ratios PI calculated from the detection signals of each color light. In this embodiment, when the abnormal value detection unit 23 detects an abnormal value 301 by the first method, it detects the sudden peak point 401 that appears in at least one of the signal intensity ratios PI calculated from the detection signals of each color light. This makes it possible to easily detect the oxygen saturation at the timing when the sudden peak point 401 is detected as an abnormal value 301 based on body movement.

[0059] In the pulse oximeter 1 of this embodiment, when the abnormal value detection unit 23 detects an abnormal value 301 by the second method, the abnormal value detection unit 23 determines a predetermined observation time T i The signal intensity ratio PI (red light signal intensity ratio PI) within a time range of Δt [sec] before and after the center. red, infrared light signal intensity ratio PI ir , green light signal intensity ratio PI grn An abnormal value 301 in the oxygen saturation data group 300 may be detected by time variation analysis of the data. When subject 9 moves, the detection signal is disturbed, causing a sudden peak point 401 to appear in the index value 231, as described above. By performing a time variation analysis of the signal intensity ratio PI, the occurrence of such a sudden peak point 401 can be easily detected, thereby easily detecting the abnormal value 301 based on body movement.

[0060] In the pulse oximeter 1 of this embodiment, the abnormal value detection unit 23 calculates the standard deviation s or variance v of the signal intensity ratio PI of n points based on the detection signals of n points output within a predetermined time range as a time variation analysis, and detects an abnormal value 301 based on the standard deviation s or variance v. When the variance v and standard deviation s are large in the fluctuation of the signal intensity ratio PI over a predetermined period, it means that a sudden peak point 401 exists during that period, and the presence or absence of a sudden peak point 401 can be accurately detected by the variance v and standard deviation s.

[0061] In the pulse oximeter 1 of this embodiment, it is more preferable that the abnormal value detection unit 23 calculates a coefficient of variation cv by normalizing the standard deviation s with the mean value of the signal intensity ratio PI as a time variation analysis, and detects the oxygen saturation at a predetermined timing as an abnormal value 301 when the coefficient of variation cv is greater than or equal to a predetermined threshold. This allows for the detection of abnormal values ​​with high accuracy, regardless of differences between individual pulse oximeters or measurement sites.

[0062] The pulse oximeter 1 of this embodiment includes a sensor unit 10 including a red light sensor 12 and an infrared light sensor 13, a control device 20 that processes the detection signals from each light sensor, and a display unit 30 that displays the information obtained by the control device 20. The control device 20 generates an oxygen saturation data group 300 indicating the oxygen saturation of the subject 9 from the detection signals of the red light sensor 12 and the infrared light sensor 13, and the red light signal intensity ratio PI red , and infrared light signal intensity ratio PI ir An index value 231 is calculated based on at least one of the above, and a graph showing the oxygen saturation data set and the index value 231 on the same time axis 32 is displayed on the display unit 30.

[0063] This allows the display unit 30 to display an index value 231 for detecting abnormal values ​​301 based on body movement, along with the oxygen saturation data set 300, and the user can easily determine the time when the subject 9 was moving based on the index value 231.

[0064] In the pulse oximeter 1 of this embodiment, the display control unit 25 of the control device 20 estimates the motion period L based on the index value 231 and displays the motion period L superimposed on the graph. This allows users to easily confirm the body movements of subject 9 by the body movement period L displayed on the graph, even if they have no prior knowledge of the index value 231.

[0065] In the pulse oximeter 1 of this embodiment, when an abnormal value 301 is detected by the first method, the display control unit 25 of the control device 20 displays a peak point image 53, which shows a sudden peak point 401 in the signal intensity ratio PI, which is the index value 231, superimposed on the graph. This allows users to easily determine the duration of subject 9's body movement and the corresponding index value 231.

[0066] In the pulse oximeter 1 of this embodiment, when an abnormal value 301 is detected by the second method, the display control unit 25 of the control device 20 calculates the analysis result of the time variation analysis of the signal intensity ratio PI as an index value 231 and displays it on the graph as an index value graph 52. This allows the user to determine the time when the subject 9 moved, similar to the invention described above.

[0067] [Other embodiments] Figure 14 shows other embodiments of the present disclosure. In Figure 14, 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 displays the current time 41, oxygen saturation level 42, body movement 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.

[0068] 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 similarly to the control device 20 described above. It measures the oxygen saturation of the subject 9 from the detection signals of the red light sensor 12 and the infrared light sensor 13 to generate an oxygen saturation data set 300, and calculates an index value 231 for detecting abnormal values ​​based on the detection signals. The index value 231 is the same as when detecting abnormal values ​​301 by the second method of the above embodiment, and is the result of the time variation analysis of the signal intensity ratio PI (variance v, or standard deviation s, or coefficient of variation cv of the signal intensity ratio PI). The control device 20A then detects motion artifacts based on the calculated index value 231. The control device 20A, at the user's operation, displays the oxygen saturation of the oxygen saturation data group 300 at the current time or any past time on the oxygen saturation display 42, and also displays the analysis results of the time variation analysis at the same time on the body movement index display 43. In the example in Figure 14, the coefficient of variation cv is the signal intensity ratio PI, for example, the red light signal intensity ratio PI red Coefficient of variation PICV red , infrared light signal intensity ratio PI ir Coefficient of variation PICV ir , and the green light signal intensity ratio PI grn Coefficient of variation PICV grn Examples include the maximum value or the average value among them.

[0069] When the control device 20A displays the oxygen saturation indicator 42 and the body movement index indicator 43, it determines whether or not a body movement artifact has been detected based on the analysis results at the time of display. If body movement is detected, it displays the analysis results on the body movement index indicator 43 in a different display mode than when no body movement is detected. For example, when the coefficient of variation cv of the signal intensity ratio PI falls below a predetermined threshold, the control device 20A displays letters or symbols on the alert display 44 (body movement display image) indicating the possibility of an abnormal value 301 due to body movement, and displays the body movement index display 43 in a different manner than when the coefficient of variation cv exceeds a predetermined threshold. In this case, the display of the oxygen saturation display 42 may also be in a different manner than when the coefficient of variation cv exceeds a predetermined threshold. Differentiation of the display manner when the coefficient of variation cv of the signal intensity ratio PI falls below a threshold may be limited to just one of the three described above. Differences in display manners can include, for example, different display manners with different saturation, brightness, transparency, line type, or combinations thereof. Furthermore, although the above shows an example of displaying the coefficient of variation cv of the signal intensity ratio PI on the body movement index display 43, the standard deviation s or variance v may also be used as the time variation analysis result.

[0070] [Effects of this embodiment] The pulse oximeter 3 of this embodiment includes a sensor unit 10A including a red light sensor 12 and an infrared light sensor 13, a control device 20A that processes the detection signals of each color, and a display unit 40 that displays the information obtained by the control device 20A. The control device 20A measures the oxygen saturation of the subject 9 from the detection signals of the red light sensor 12 and the infrared light sensor 13 to generate an oxygen saturation data group 300, and the red light signal intensity ratio PI red , and infrared light signal intensity ratio PI ir The analysis results of at least one of the time variation analyses are calculated as an index value 231, and the oxygen saturation and the analysis results of the time variation analysis are displayed on the display unit 40. In addition, the oxygen saturation or analysis results are displayed in different display formats depending on whether the analysis result is above a predetermined threshold or below the threshold.

[0071] In this pulse oximeter 3, the oxygen saturation of the subject 9 is measured by 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. Furthermore, the control device 20A can help the user recognize the reliability of the measurement results by displaying the oxygen saturation or analysis results in different ways depending on whether the analysis results of the time variation analysis are above or below the threshold.

[0072] In this embodiment, the pulse oximeter 3 changes the display color or character format of the oxygen saturation displayed on the oxygen saturation display 42 or the analysis result displayed on the body movement index display 43 when the analysis result falls below a threshold. This allows the user to more easily grasp the body movements of the subject 9 by observing changes in the display color or character format of the oxygen saturation or analysis results displayed on the display unit 40.

[0073] In this embodiment, the pulse oximeter 3 displays an alert display 44 (body movement display image) on the display unit 40 indicating that body movement is present when the analysis result falls below a threshold. This allows the user to monitor the subject's movements by checking alert display 44.

[0074] [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.

[0075] The present invention is not limited to the reflective pulse oximeter described in the embodiments, but can also be used with a transmissive pulse oximeter. That is, the sensor unit 10 may be configured to include a red light sensor that detects the red light transmitted through the subject when red light is irradiated onto the subject from a red light source, an infrared light sensor that detects the red light transmitted through the subject when infrared light is irradiated onto the subject from an infrared light source, and a green light sensor that detects the green light transmitted through the subject when green light is irradiated onto the subject from a green light source.

[0076] In the above embodiment, the invention was described as a pulse oximeter for measuring 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, a pulse oximeter should be understood to include a blood oxygen wellness device. Furthermore, although the above embodiment illustrates a device for measuring blood oxygen saturation, the present invention can be applied to other bio-optical measurements that detect motion artifacts from the analysis of the signal intensity ratio PI. For example, the present invention may be applied to a device for measuring arterial blood glucose concentration.

[0077] In the above embodiment, a configuration in which the sensor unit 10 includes a green light sensor 11, a red light sensor 12, and an infrared light sensor 13 was illustrated. However, as mentioned above, the detection signals from the red light sensor 12 and the infrared light sensor 13 are used to measure oxygen saturation. Therefore, a configuration without the green light sensor 11 is also possible. However, by providing the green light sensor 11, it is possible to detect motion artifacts with greater accuracy, and therefore, it is preferable to have a configuration that includes the green light sensor 11.

[0078] [Summary of this disclosure] A pulse oximeter according to a first 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; and a control device that processes the detection signals of the red light sensor and the infrared light sensor, wherein the control device includes: an oxygen saturation measurement unit that generates a group of oxygen saturation data indicating the oxygen saturation of the subject from the detection signals of the red light sensor and the infrared light sensor; and an abnormal value detection unit that detects abnormal values ​​of the oxygen saturation data based on the body movement of the subject based on at least one of a red light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the red light sensor to the signal intensity of the detection signal, and an infrared light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the infrared light sensor to the signal intensity of the detection signal.

[0079] Such pulse oximeters can detect abnormal values ​​in oxygen saturation data based on the subject's body movement by using the signal intensity ratio of detection signals from a red light sensor and an infrared light sensor, enabling highly accurate oxygen saturation measurement. Furthermore, abnormal values ​​based on body movement can be detected without using other sensors, such as acceleration sensors. In other words, abnormal values ​​based on body movement can be detected using the detection signals from red light sensors or infrared light sensors used to measure oxygen saturation, which simplifies the configuration of the pulse oximeter compared to incorporating a separate component for detecting body movement, such as an acceleration sensor.

[0080] In the pulse oximeter of this embodiment, it is preferable that the abnormal value detection unit detects the oxygen saturation at the timing in which the sudden peak point was obtained as the abnormal value when a sudden peak point is detected in which the difference between a plurality of peak values ​​included in at least one of the red light signal intensity ratio and the infrared light signal intensity ratio and other peak values ​​included within a predetermined period is greater than or equal to a predetermined value. When the subject moves, the detection signal is disturbed, resulting in the appearance of abrupt peaks in the index value. Therefore, by detecting these abrupt peaks in the index value—that is, peaks where the difference between one peak value and other peak values ​​within a predetermined period exceeds a predetermined value—the oxygen saturation at the time the peak point was detected can be easily detected as an abnormal value based on body movement.

[0081] In the pulse oximeter of this embodiment, the abnormal value detection unit may detect the abnormal value of oxygen saturation by analyzing the time variation of at least one of the red light signal intensity ratio and the infrared light signal intensity ratio within a predetermined time range centered on a predetermined timing. When the subject moves, the detection signal is disturbed, causing sudden peak values ​​in the index, as described above. By performing time variation analysis of the index value, the occurrence of such sudden peak values ​​can be easily detected, thereby easily detecting abnormal values ​​based on body movement.

[0082] In the pulse oximeter of this embodiment, it is preferable that the abnormal value detection unit calculates the standard deviation or variance of at least one of the ratio of the red light signal intensity and the ratio of the infrared light signal intensity of the n points based on the n detection signals output within the predetermined time range as part of the time variation analysis, and detects the abnormal value based on the standard deviation or variance. When the variance and standard deviation of the signal intensity ratio fluctuate over a predetermined period, it indicates the presence of a sudden peak value during that period. Therefore, the presence or absence of a sudden peak value can be accurately detected using variance and standard deviation.

[0083] In the pulse oximeter of this embodiment, the abnormal value detection unit, as part of the time variation analysis, calculates at least one of the coefficient of variation of the red light signal intensity ratio obtained by normalizing the standard deviation of the red light signal intensity ratio of the n points based on the detection signals of the n points output within the predetermined time range by the average value of the red light signal intensity ratio of the n points, and the coefficient of variation of the infrared light signal intensity ratio obtained by normalizing the standard deviation of the infrared light signal intensity ratio of the n points by the average value of the infrared light signal intensity ratio of the n points, and more preferably detects the oxygen saturation data at the predetermined timing as an abnormal value when the coefficient of variation is equal to or greater than a predetermined threshold. The coefficient of variation cv of the signal intensity ratio PI can be used as a constant detection index regardless of differences between individual pulse oximeters 1 or differences in measurement sites. Therefore, the coefficient of variation cv(PICV) red PICV ir PICV grn The detection of abnormal values ​​based on this method can detect abnormal values ​​with high accuracy, regardless of differences between pulse oximeters and measurement sites.

[0084] 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 information obtained by the control device. The control device generates a group of oxygen saturation data indicating the oxygen saturation of the subject from the detection signals from the red light sensor and the infrared light sensor, calculates an index value based on at least one of a red light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the red light sensor to the signal intensity of the detection signal, and an infrared light signal intensity ratio indicating the ratio of the amplitude of the vibration component in the detection signal output by the infrared light sensor to the signal intensity of the detection signal, and displays a graph on the display unit showing the oxygen saturation data group and the index value on the same time axis.

[0085] In this type of pulse oximeter, a red light sensor, an infrared light sensor, and a control unit obtain a set of oxygen saturation data for the subject's blood oxygen saturation. The control unit also displays an index value on the display unit for detecting abnormal values ​​based on body movement, along with the oxygen saturation data. This allows the user to easily determine the duration of the subject's body movement based on the index value.

[0086] In the pulse oximeter of this embodiment, it is preferable that the control device estimates the period during which the subject's body movement occurred based on the index value, and displays the period during which the body movement occurred superimposed on the graph. This allows users to easily confirm the period during which the subject's body movement occurred, even if they lack knowledge of the indicator values, by displaying the estimated period of body movement based on the abnormal values ​​on the display unit.

[0087] In the pulse oximeter of this embodiment, it is preferable that the control device uses at least one of the red light signal intensity ratio and the infrared light signal intensity ratio as the index value, and displays a peak point image superimposed on the graph, which shows a sudden peak point in which the difference between a plurality of peak values ​​included in the index value and other peak values ​​included within a predetermined period is greater than or equal to a predetermined value. This allows users to easily understand the duration of the subject's body movement and the corresponding indicator values.

[0088] In the pulse oximeter of this embodiment, the control device may perform a time variation analysis of at least one of the red light signal intensity ratio and the infrared light signal intensity ratio within a predetermined time range centered on a predetermined timing, and display the analysis results of the time variation analysis superimposed on the graph as the index value. As described above, in addition to identifying sudden peaks in the indicator values, it is also possible to understand the subject's body movements by using time-varying analysis of the indicator values. Therefore, by displaying the results of such time-varying analysis of indicator values ​​on the display unit, the user can understand the time periods when the subject's body movements occurred, similar to the embodiment described above.

[0089] 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, wherein the control device calculates the oxygen saturation of the subject from the detection signals from the red light sensor and the infrared light sensor, and the red light sensor outputs The system calculates an index value from the analysis results of at least one of the time variation analyses of the red light signal intensity ratio, which shows the ratio of the amplitude of the vibration component in the detected signal to the signal intensity of the detected signal, and the infrared light signal intensity ratio, which shows the ratio of the amplitude of the vibration component in the detected signal output by the infrared light sensor to the signal intensity of the detected signal. The system then displays the oxygen saturation and the analysis results on the display unit, and displays the oxygen saturation or the analysis results in different display formats depending on whether the analysis results are above a predetermined threshold or below the threshold.

[0090] In such a pulse oximeter, the oxygen saturation level of the subject is obtained using a red light sensor, an infrared light sensor, and a control device. The control device displays the oxygen saturation level along with the results of a time-varying analysis of an index value for detecting the subject's body movement, allowing the user to easily determine the subject's body movement.

[0091] In the pulse oximeter of this embodiment, it is preferable to change the display color or character format of the oxygen saturation or the analysis result when the analysis result falls below the threshold. This allows users to more easily perceive the subject's body movements through changes in the display color or font style of the oxygen saturation or analysis results shown on the display unit.

[0092] In the pulse oximeter of this embodiment, it is preferable to display a motion display image indicating that there is motion when the analysis result is less than the threshold. This allows users to more easily understand the subject's body movements by viewing the motion display images. [Explanation of symbols]

[0093] 1,3…Pulse oximeter, 9…Subject, 10,10A…Sensor unit, 11…Green light sensor, 12…Red light sensor, 13…Infrared light sensor, 20,20A…Control device, 21…Signal acquisition unit, 22…Saturation measurement unit, 23…Abnormal value detection unit, 24…Data processing unit, 25…Display control unit, 30,40…Display unit, 31,31A…Display screen, 32…Time axis, 33…Vertical axis display, 42…Oxygen saturation display, 43…Body movement index display, 44…Alert display, 51…Oxygen saturation graph, 52,52A…Index value graph, 53…Peak point image, 54…Body movement display unit, 55…Threshold display unit, 231…Index value, 300…Oxygen saturation data group, 301…Abnormal value, 310…Abnormality removal data group, 320…Corrected data group, 321…Interpolation data, L…Body movement period.

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 An oxygen saturation measurement unit that generates a set of oxygen saturation data indicating the oxygen saturation of the subject from the detection signals of the red light sensor and the infrared light sensor, An abnormal value detection unit that detects abnormal values ​​in the oxygen saturation data based on the body movement of a subject, based on at least one of the following: a red light signal intensity ratio, which shows the ratio of the amplitude of the vibration component in the detection signal output by the red light sensor to the signal intensity of the detection signal; and an infrared light signal intensity ratio, which shows the ratio of the amplitude of the vibration component in the detection signal output by the infrared light sensor to the signal intensity of the detection signal. A pulse oximeter equipped with the following features.

2. The abnormal value detection unit detects the oxygen saturation at the time the sudden peak point was obtained as the abnormal value when a sudden peak point is detected in which the difference between a plurality of peak values ​​included in at least one of the red light signal intensity ratio and the infrared light signal intensity ratio and other peak values ​​included within a predetermined period exceeds a predetermined value. The pulse oximeter according to claim 1.

3. The abnormal value detection unit detects the abnormal value of oxygen saturation by analyzing the time variation of at least one of the red light signal intensity ratio and the infrared light signal intensity ratio within a predetermined time range centered on a predetermined timing. The pulse oximeter according to claim 1.

4. The abnormal value detection unit, as part of the time variation analysis, calculates the standard deviation or variance of at least one of the ratio of the red light signal intensity and the ratio of the infrared light signal intensity of the n points based on the n detection signals output within the predetermined time range, and detects the abnormal value based on the standard deviation or variance. The pulse oximeter according to claim 3.

5. The abnormal value detection unit, as part of the time variation analysis, calculates at least one of the following: the coefficient of variation of the red light signal intensity ratio obtained by normalizing the standard deviation of the red light signal intensity ratio of the n points based on the n detection signals output within the predetermined time range by the average value of the red light signal intensity ratio of the n points; and the coefficient of variation of the infrared light signal intensity ratio obtained by normalizing the standard deviation of the infrared light signal intensity ratio of the n points by the average value of the infrared light signal intensity ratio of the n points. If the coefficient of variation is greater than or equal to a predetermined threshold, the unit detects the oxygen saturation data at the predetermined timing as an abnormal value. The pulse oximeter according to claim 3.

6. 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 is A set of oxygen saturation data indicating the oxygen saturation of the subject is generated from the detection signals of the red light sensor and the infrared light sensor. An index value is calculated based on at least one of the following: the red light signal intensity ratio, which represents the ratio of the amplitude of the vibration component in the detection signal output by the red light sensor to the signal intensity of the detection signal; and the infrared light signal intensity ratio, which represents the ratio of the amplitude of the vibration component in the detection signal output by the infrared light sensor to the signal intensity of the detection signal. A pulse oximeter that displays a graph on its display unit showing the oxygen saturation data set and the index value on the same time axis.

7. The control device estimates the period during which the subject's body movement occurred based on the index value, and displays the period during which the body movement occurred superimposed on the graph. The pulse oximeter according to claim 6.

8. The control device uses at least one of the red light signal intensity ratio and the infrared light signal intensity ratio as the index value, and overlays a peak point image on the graph that indicates a sudden peak point where the difference between a plurality of peak values ​​included in the index value and other peak values ​​included within a predetermined period is greater than or equal to a predetermined value. The pulse oximeter according to claim 6.

9. The control device performs a time variation analysis of at least one of the red light signal intensity ratio and the infrared light signal intensity ratio within a predetermined time range centered on a predetermined timing, and displays the analysis results of the time variation analysis superimposed on the graph as the index value. The pulse oximeter according to claim 6.

10. 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 is The oxygen saturation of the subject is calculated from the detection signals of the red light sensor and the infrared light sensor. The analysis results of at least one of the time variation analyses of the red light signal intensity ratio, which represents the ratio of the amplitude of the vibration component in the detection signal output by the red light sensor to the signal intensity of the detection signal, and the infrared light signal intensity ratio, which represents the ratio of the amplitude of the vibration component in the detection signal output by the infrared light sensor to the signal intensity of the detection signal, are calculated as index values. A pulse oximeter that displays the oxygen saturation and the analysis result on the display unit, and displays the oxygen saturation or the analysis result in different display formats depending on whether the analysis result is above a predetermined threshold or below the threshold.

11. If the analysis result is less than the threshold, the display color or text format of the oxygen saturation or the analysis result is changed. The pulse oximeter according to claim 10.

12. If the analysis result is less than the threshold, a motion display image indicating that there is body movement is displayed. The pulse oximeter according to claim 10.

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