JP2009261463A - Oxygen saturation measurement apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen saturation measurement apparatus which allows a user to recognize the stability level without continuously looking at displayed values of blood oxygen saturation (SpO<SB>2</SB>values). <P>SOLUTION: The oxygen saturation measurement apparatus 100 comprises: a measurement section 2 that acquires a living body information signal by emitting infrared light or red light to a living body and receiving light passed through the living body; an analysis processing section 42 that calculates blood oxygen saturation by analyzing and processing the living body information signal; a stability determination section 43 that determines the stability and the stability level of the blood oxygen saturation on the basis of the value acquired by analysis and processing of the analysis processing section 42; and a display section 6 that displays the blood oxygen saturation calculated by the analysis processing section 42. When the blood oxygen saturation is determined to be stable by the stability determination section 43, the display section 6 displays the blood oxygen saturation in a fixed manner and also displays the stability level acquired when the stability determination section 43 determines that the blood oxygen saturation is stable. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an oxygen saturation measuring apparatus that measures the oxygen saturation of arterial blood.

The pulse oximeter is an important measuring device for knowing the health condition of a patient (subject). Specifically, the pulse oximeter is attached to a predetermined living body part of a patient, outputs light toward the living body part, measures a change in the amount of light transmitted or reflected through the living body part as a signal, and SpO ₂ value. Etc. For example, blood oxygen saturation (hereinafter referred to as SpO ₂ value) may be measured by a pulse oximeter (oxygen saturation measuring device) at the time of hospital outpatient reception, etc., as in body temperature measurement. In particular, in the cardiovascular ward, in-patients may be equipped with a pulse oximeter to measure the patient's SpO ₂ value as a daily health check.

For example, in a patient with respiratory failure, the SpO ₂ value temporarily decreases abruptly just by walking. In such a state, the SpO ₂ value is not stable and a correct value cannot be measured. Therefore, after mounting the pulse oximeter to the patient, until the SpO ₂ value is stabilized, it is necessary to visually confirm the SpO ₂ value displayed. The read SpO ₂ value is a correct value while the SpO ₂ value is stable. This operation is usually performed by a nurse or the like (operator), but since it is visually confirmed, other operations cannot be performed during this period.

For example, Patent Document 1, the SpO ₂ value displayed at any time, determined the stability of the SpO ₂ values, when the SpO ₂ value is judged to be stable, without subsequent measurements, at that time An oximeter is described that continues to display the displayed SpO ₂ value as is (fixed display). Here, Formula 1 shown below is used for the determination of the stability of the oximeter. In Equation 1, DS is a determination value, and W (I) is a weighting factor. S (0) represents the currently displayed SpO ₂ value, S (-1) represents the previous SpO ₂ value, and S (-2) displayed the previous two. It represents the SpO ₂ value. W (I) is a value determined by I.

The determination value DS obtained by Equation 1 indicates that the smaller the value is, the less variation in the displayed SpO ₂ value is, and the higher the stability is. Thus, the oximeter described in Patent Document 1, if the decision value DS is equal to or less than a predetermined threshold value SpO ₂ value is determined to be stable, and the fixed displays the SpO ₂ value displayed at that time To do. Thus, the operator can recognize the correct SpO ₂ value, which is a stable value, only by reading the value when it is fixedly displayed without continuing to visually observe the SpO ₂ value displayed on the oximeter. it can.
Japanese Patent Publication No. 7-32767

Here, not only the stable SpO ₂ value but also the degree of stability known from the SpO ₂ value until stabilization is useful information for understanding the health condition of the patient. However, as described above, the oximeter described in Patent Document 1 can recognize the SpO ₂ value after stabilization, but in order to recognize the SpO ₂ value until it is stabilized, the displayed SpO ₂ value is changed. It must continue to be monitored visually. As a result, there is a problem that the operator cannot perform other operations while performing the measurement with the oximeter. In addition, when other work must be performed in parallel when measuring with an oximeter, the degree of stability cannot be recognized.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an oxygen saturation measuring apparatus that can recognize the degree of stability without continuously viewing the displayed SpO ₂ value. That is.

  As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, the oxygen saturation measuring apparatus according to an aspect of the present invention includes a measuring unit that irradiates a living body with infrared light and red light and receives light that has passed through the living body to obtain a biological information signal; Analyzing the biological information signal to calculate blood oxygen saturation, and based on the value obtained by performing analytical processing in the analysis processing unit, the stability of blood oxygen saturation and A stability determination unit that determines the degree of stability; and a display unit that displays the blood oxygen saturation calculated by the analysis processing unit, wherein the display unit includes a blood oxygen saturation level in the stability determination unit. When the blood oxygen saturation is determined to be stable, the blood oxygen saturation is fixedly displayed, and the degree of stability is determined when the blood oxygen saturation is determined to be stable by the stability determination unit. indicate. Note that the fixed display means that the currently displayed value is continuously displayed as it is regardless of the current measurement value.

  In this way, when the value is stable, not only is it fixed display, but also the degree of stability is displayed, so the operator can monitor the degree of stability by continuing to look until the displayed value is stable There is no need to keep it. Therefore, the operator can perform other operations during the measurement. And when it is set as fixed display, the value of blood oxygen saturation and the degree of stability are read from a display part, and a test subject's health state can be recognized by it.

  In the above-described oxygen saturation measuring apparatus, it is preferable that the degree of stability includes at least one of a maximum value, a minimum value, and an average value of blood oxygen saturation within the determination target period. In the stability determination, the current value obtained by the latest measurement and the value obtained by the past measurement are used, and the period during which the values used for the determination are measured is referred to as a determination target period.

  Thereby, since the maximum value, the minimum value, or the average value of the blood oxygen saturation is used as the degree of stability, it is easy to recognize the degree of stability.

  Further, in the above-described oxygen saturation measurement apparatus, after the display unit sets the blood oxygen saturation to the fixed display, when the stability determination unit determines that the blood oxygen saturation is not stable, It is preferable that the display unit cancels the fixed display.

  As a result, when the blood oxygen saturation suddenly changes after the fixed display, the blood oxygen saturation measured by the current measurement is displayed. Therefore, even when the blood oxygen saturation level changes suddenly after the fixed display, the operator can recognize the change.

  Moreover, in the above-described oxygen saturation measuring apparatus, it is preferable to further include a power supply unit that turns off the power when the duration of the fixed display is equal to or longer than a predetermined time.

  Thereby, it has an energy saving effect.

  Moreover, in the above-described oxygen saturation measuring apparatus, it is preferable that the display unit stops displaying when the duration of the fixed display is equal to or longer than a predetermined time.

  Thereby, it has an energy saving effect.

  Moreover, in the above-described oxygen saturation measurement apparatus, it is preferable that the measurement unit stops the measurement when the duration of the fixed display is equal to or longer than a predetermined time.

  Thereby, it has an energy saving effect.

According to the present invention, it is possible to provide an oxygen saturation measuring apparatus capable of recognizing the degree of stability without continuously viewing the displayed SpO ₂ value.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

  A pulse oximeter that is an oxygen saturation measuring apparatus according to an embodiment of the present invention will be described. First, the configuration of the pulse oximeter according to the embodiment will be described. FIG. 1 is a diagram showing an external configuration of a pulse oximeter according to an embodiment. FIG. 2 is a block diagram showing the configuration of the pulse oximeter according to the embodiment.

As shown in FIG. 1, the pulse oximeter 100 includes a device main body 1 and a measuring unit 2 electrically connected to the device main body 1 via a cable 16. The pulse oximeter 100 is used by being attached to a hand 300 of a subject (patient). The apparatus main body 1 has a mounting belt 17, and the apparatus main body 1 is fixed to the wrist of the subject by, for example, winding the mounting belt 17 around the wrist of the subject. The apparatus body 1 further includes a display unit 6 and an operation unit 8. The display unit 6 is for displaying biological information such as measurement results, that is, blood oxygen saturation (SpO ₂ value). The operation unit 8 is, for example, a switch circuit or the like, and is used to give an instruction to start or end measurement.

  The measuring unit 2 is attached to, for example, the fingertip of the subject. Specifically, it has a shape like a finger sack and is worn by being fitted to the fingertip of the subject. Although not shown in FIG. 1, measurement is performed by the light emitting unit 21 and the light receiving unit 22 installed inside the measuring unit 2 (see FIG. 2).

  Furthermore, with reference to FIG. 2, the electrical configuration of the pulse oximeter 100 according to the embodiment will be described. The pulse oximeter 100 includes an apparatus main body 1 and a measurement unit 2. The measuring unit 2 includes a light emitting unit 21 and a light receiving unit 22, and in a state where a measurement site (for example, a fingertip) is fitted into the measuring unit 2, that is, in a measurement state, the light emitting unit 21 and the light receiving unit 22 are between them. It arrange | positions so that it may oppose via a fingertip. Thereby, biological information can be measured based on the transmitted light of the measurement site. In addition, biological information can also be measured based on the reflected light of the measurement site, and in this case, the light emitting unit 21 and the light receiving unit 22 are arranged adjacent to each other.

  The light emitting unit 21 is a light source including, for example, a light emitting diode that emits red light having a wavelength in the red region and a light emitting diode that emits infrared light having a wavelength in the infrared region. In order to obtain an appropriate level of output even if the thickness of the fingertip that is the measurement site or the light receiving sensitivity of the light receiving unit 22 is different, the amount of irradiation light can be adjusted within a certain range during measurement. It is preferable to do.

  The light receiving unit 22 includes a photoelectric conversion element such as a silicon photodiode that generates a current having a magnitude corresponding to the intensity of received light. The light receiving unit 22 receives light from the light emitting unit 21 that has passed through the fingertip of the subject as the measurement site. Therefore, this photoelectric conversion element has sensitivity to red light and infrared light emitted from the light emitting unit 21. Specifically, the light receiving unit 22 converts optical signals of red light and infrared light into electrical signals that are biological information signals and outputs the electrical signals.

  The apparatus body 1 includes a control unit 4, a storage unit 5, a display unit 6, a power supply unit 7, an operation unit 8, a notification unit 9, an I / V conversion unit 31, and an A / D conversion unit 32. It has.

The storage unit 5 includes a ROM (Read Only Memory) that stores a control program of the pulse oximeter 100, an EEPROM (Electrically Erasable Programmable ROM) that temporarily stores data such as arithmetic processing and control processing, and a RAM (Random Access). Memory) and flash memory. In the storage unit 5, the biological information signal obtained by the measurement unit 2 is analyzed by the analysis processing unit 42, and the light amount and pulse wave amplitude of each light received by the light receiving unit 22, infrared light and red color are obtained. The amplitude ratio with light, the instantaneous SpO ₂ value, the display SpO ₂ value, and the like are stored in association with time measurement information such as measurement time output by a timer function provided in the CPU. The determination of the stability of the SpO ₂ value uses not only the current measurement result but also the data based on the measurement result that goes back in the past for a certain period of time. Can be easily read out. Note that the time measurement information may be time from the start of measurement or time.

The display unit 6 may be an LCD (Liquid Crystal Display) display device, for example. In addition, a display device such as a 7-segment LED (Light Emitting Diode) display device, an organic electroluminescence display device, or a CRT (Cathode-Ray Tube) display device may be used. The display unit 6 displays, for example, SpO ₂ value, which is measured biological information, information indicating that measurement is in progress or fixed display, a degree of stability, and the like. For example, the display unit 6 may display lighting, blinking, characters, numbers, symbols, pictorial symbols, characters, and the like.

  The power supply unit 7 supplies power to the pulse oximeter 100, that is, the measurement unit 2 and the apparatus main body 1. Considering the troublesomeness when the pulse oximeter 100 is mounted, it is desirable to eliminate the need for a power supply cable. Therefore, the power supply unit 7 may include a button battery, a secondary battery, and the like. The power supply unit 7 includes a power supply circuit having a power-off function that automatically stops the power supply when the fixed display continues for a certain period of time.

  The operation unit 8 is configured with switches and buttons for operating the pulse oximeter 100. Specifically, a switch for turning on / off the power, a switch for instructing measurement start, and various other operations are provided.

The notification unit 9 notifies the operator of, for example, an alarm sound that the display of the measurement value is fixed because the SpO ₂ value is stable, and that a predetermined time has elapsed since the measurement was started. In addition, the alerting | reporting part 9 is not restricted to notifying an operator of the said state by audio | voices, such as an alarm sound. For example, a vibration device may be used to notify the operator of the above state by vibration instead of an alarm sound, or may be provided with an LED or the like, for example, to notify the operator of the above state by lighting or blinking the LED.

  The I / V conversion unit 31 converts a current signal output from the light receiving unit 22 into a voltage signal at a predetermined cycle, and outputs the voltage signal to the A / D conversion unit 32 as a photoelectric pulse wave signal.

  The A / D conversion unit 32 converts the photoelectric pulse wave signal, which is an analog biological information signal output from the I / V conversion unit 31, into a digital photoelectric pulse wave signal and outputs it to the control unit 4.

  The control unit 4 includes various electronic components, integrated circuit components, a CPU (Central Processing Unit), and the like, and controls the operation of each unit of the pulse oximeter 100. The control unit 4 functionally includes a measurement control unit 41, an analysis processing unit 42, A stability determination unit 43 and a display control unit 44 are provided.

  The measurement control unit 41 controls the measurement operation of biological information by the measurement unit 2 according to a predetermined measurement program. Specifically, red light and infrared light are alternately emitted from the light emitting unit 21 at each sampling period, and a photoelectric conversion signal is acquired from the light receiving unit 22 in synchronization with the light emission timing.

The display control unit 44 controls the display operation of the display unit 6. Specifically, the display unit 6 displays the SpO ₂ value calculated by analyzing the biological information signal obtained by the display representing the state under measurement or the measurement by the analysis processing unit 42 in a predetermined display form. The display operation to be controlled is controlled. If the stability determination unit 43 determines that the stability of the SpO ₂ value is high, the display unit 6 is controlled so that the currently displayed SpO ₂ value is fixed. The display unit 6 is also controlled for releasing the fixed display. Further, when the display unit 6 uses the SpO ₂ value as a fixed display, the display unit 6 is controlled to display that the display is a fixed display and the degree of stability at that time. The degree of stability includes a maximum value, a minimum value, an average value, and the like during the determination target period, and the display control unit 44 controls the display unit 6 to display them. Note that at least one of the maximum value, the minimum value, and the average value may be displayed.

The analysis processing unit 42 performs predetermined data analysis based on the biological information signal obtained by the measurement unit 2, and the light amount and pulse wave amplitude of each light received by the light receiving unit 22, the infrared light and the red light. An amplitude ratio, an instantaneous SpO ₂ value, and the like are obtained. Not only instantaneous SpO ₂ value is SpO ₂ value at each sampling period, it may be calculated one second SpO ₂ value is SpO ₂ value at every one second. Further, an average value or a moving average value of the instantaneous SpO ₂ value in a predetermined period is calculated, and a display SpO ₂ value that is a value to be displayed on the display unit 6 is obtained.

Oxygen is transported by the oxidation and reduction of hemoglobin in the blood. When this hemoglobin is oxidized, the absorption of red light decreases and the absorption of infrared light increases. Conversely, when it is reduced, the absorption of red light increases and the absorption of infrared light decreases. It has characteristics. The analysis processing unit 42 calculates the SpO ₂ value using this characteristic. Specifically, first, the variation in the amount of transmitted light of red light and infrared light received by the light receiving unit 22 is measured, and the instantaneous SpO ₂ value for each sampling period is calculated based on the amplitude ratio of the red light and infrared light. To do. Further, for example, an average value or a moving average value in a predetermined range of the calculated instantaneous SpO ₂ value is obtained, and this is set as a display SpO ₂ value. The display SpO ₂ value is displayed on the display unit 6 by the display control unit 44. Note that the display SpO ₂ value may be calculated every sampling period, or may be calculated every predetermined period, for example, every second.

The stability determination unit 43 calculates the stability of the SpO ₂ value and the degree of stability when it is stable. For example, the stability determination may be performed using Equation 1 described above. Specifically, the stability determination unit 43 may determine DS by calculating DS by substituting the display SpO ₂ value calculated by the analysis processing unit 42 into Equation 1. Here, W (I) in Equation 1 is a weighting factor, which can be arbitrarily determined. W (I) may be a value greater than 0 and less than or equal to 1, for example. In Formula 1, since the stability at the present time is determined, when the display SpO ₂ value calculated in the past is used, that is, as the value of I is smaller, the value of W (I) may be decreased. . In some cases, W (I) may be a fixed value. S (0) indicates the display SpO ₂ value currently displayed on the display unit 6. That is, it is the latest display SpO ₂ value among the values calculated by the analysis processing unit 42. Further, S (−1) represents the SpO ₂ value displayed one time before. That is, the display SpO ₂ value calculated by the analysis processing unit 42 one time before. Further, S (−2) represents the display SpO ₂ value displayed two times before. That is, the display SpO ₂ value calculated by the analysis processing unit 42 two times before.

DS is a calculated display SpO ₂ values, are multiplied by W (I) to the difference between calculated display SpO ₂ values prior one, the latest calculated value (current display SpO ₂ value) To the display SpO ₂ value calculated before 5 points. That is, in order to obtain DS, six points of display SpO ₂ values are required. Therefore, DS is a measure of the most recent variation in the display SpO ₂ value. Not only latest display SpO ₂ values, for display SpO ₂ values in a past measurement, so in association with the time information stored in the storage unit 5, stability judging unit 43 can be easily read .

The stability determination unit 43 sets a predetermined threshold value in the DS obtained by Equation 1, and determines that the DS is stable when the DS is equal to or less than the threshold value. Note that the smaller the DS, the higher the stability because it can be said that there is less immediate variation in the display SpO ₂ value. Therefore, the degree of stability can be determined from the value of DS. Specifically, since 0 is the minimum value for the DS value, the range from 0 to the threshold value may be further divided into 10 equal parts, and the degree of stability may be determined in 10 steps based on each value. For example, when the predetermined threshold is Th, the threshold at each stage is represented by B (i). Note that i is an integer of 0 to 9, and the larger i is, the larger B (i) is. For example, B (0) = Th / 10, B (1) = (Th / 10) × 2 = Th / 5, B (2) = (Th / 10) × 3, B (3) = (Th / 10) ) × 4 = Th × 2/5, B (4) = (Th / 10) × 5 = Th / 2, B (5) = (Th / 10) × 6− = Th × 3/5, B (6 ) = (Th / 10) × 7, B (7) = (Th / 10) × 8 = Th × 4/5, B (8) = (Th / 10) × 9, B (9) = (Th / 10) × 10 = Th. If DS is 0 or more and B (0) or less, the stability is 10, and if DS is greater than B (0) and less than or equal to B (1), the stability is 9 and DS is greater than B (1) and B ( 2) Stability is 8 if DS or less, stability is 7 if DS is greater than B (2) and B (3) or less, and stability is DS if DS is greater than B (3) and B (4) or less 6. Stability is 5 if DS is greater than B (4) and less than B (5), stability is 4 if DS is greater than B (5) and less than B (6), DS is B (6) Greater than B (7), the stability is 3, and if DS is greater than B (7) and less than B (8), the stability is 2, and DS is greater than B (8) and less than B (9). If so, the degree of stability may be determined with a stability of 1. Note that the degree of stability is not limited to 10 levels, and the set level may be increased or decreased as appropriate. Further, in the above description, the threshold intervals in each stage represented by B (i) are set to be equal intervals, but they may be changed according to the stages instead of being equal intervals. For example, by increasing the threshold interval as i increases, the degree of stability is determined more severely as the stability increases.

Note that the determination of whether or not it is stable and the determination of the degree of stability are not limited to the method according to Equation 1 as described above, and other methods may be used. For example, in addition to the determination using the display SpO ₂ value, the light amount and pulse wave amplitude of each light received by the light receiving unit 22, the amplitude ratio between infrared light and red light, the 1 second SpO ₂ value, and the instantaneous SpO _{2 The} stability may be determined by combining any or all of these data including binary values or the display SpO ₂ values. These past data are also stored in the storage unit 5. For example, the stability of the SpO ₂ value may be determined from the variation or average value of these data, and the degree of stability may be determined based on the stability. Specifically, the stability determination unit 43 calculates the minimum value and the maximum value among the respective data in the determination target period, and is stable if the difference between the minimum value and the maximum value is equal to or less than a predetermined value. The degree of stability may be determined according to the magnitude of the difference. In the determination of the stability, the current value obtained by the latest measurement and the value obtained by the past measurement are used, and the period in which the values used for the determination are measured is referred to as a determination target period.

  In addition, the stability determination unit 43 compares the average values for each determination target period obtained while shifting the determination target period, and determines that the average value is stable if the variation of the average value is equal to or less than a predetermined value. May be. Furthermore, the degree of stability may be determined according to the size of the variation. In addition, regarding the light quantity and pulse wave amplitude of each light, the higher the signal level, the better the SN ratio (Signal to Noise Ratio), so the stability is high when the signal level is high. It may be determined and the degree of stability may be determined.

  Next, the operation of the pulse oximeter will be described with reference to FIGS. FIG. 3 is a flowchart showing the operation of the pulse oximeter according to the embodiment. FIG. 4 is a flowchart for explaining the procedure for determining stability and determining the degree of stability.

First, the pulse oximeter 100 is attached to the subject's hand 300, and the measurement is started by operating the operation unit 8 (S1). When an instruction to start measurement is given from the operation unit 8 to the control unit 4, the measurement control unit 41 controls the light emitting unit 21, the light receiving unit 22, the I / V conversion unit 31, and the A / D conversion unit 32 to perform SpO _2. Measurement of biological information such as values is performed. The measurement control unit 41 causes the light emitting unit 21 to emit light and causes the light receiving unit 22 to acquire a photoelectric conversion signal that is a biological information signal in synchronization with the light emission timing. Further, the photoelectric conversion signal acquired by the light receiving unit 22 is a current signal, is converted into a voltage signal by the I / V conversion unit 31, and is output to the A / D conversion unit 32 as a photoelectric pulse wave signal. The measurement control unit 41 causes the A / D conversion unit 32 to convert the photoelectric pulse wave signal from analog to digital.

The analysis processing unit 42 performs a predetermined analysis based on the digital photoelectric pulse wave signal output from the A / D conversion unit 32, and the light amount and pulse wave amplitude of each light received by the light receiving unit 22 and infrared light. Amplitude ratio with red light, instantaneous SpO ₂ value, 1 second SpO ₂ value, display SpO ₂ value and the like are calculated. The display control unit 44 causes the display unit 6 to sequentially display the display SpO ₂ value calculated by the analysis processing unit 42. Further, the analysis processing unit 42 sequentially stores the calculated various data in the storage unit 5 together with the timing information. Note that the data stored in the storage unit 5 only needs to be used for stability determination and determination of the degree of stability.

The stability determination unit 43 reads out the latest measurement value calculated by the analysis processing unit 42 and the data in the past measurement used for the stability determination from the storage unit 5, and determines the stability and the degree of stability by the method described above. Make a decision. First, it is determined whether or not the measured value is stable by determining the stability (S2). When it is determined that the measured value is stable, the display control unit 44 fixedly displays the latest display SpO ₂ value on the display unit 6 (S3). That is, even if a new display SpO ₂ value is calculated, the display unit 6 continues to display the currently displayed display SpO ₂ value. Note that, even after the fixed display, the measurement unit 2 continues the measurement, the data obtained by the measurement is analyzed by the analysis processing unit 42, and the calculated data is stored in the storage unit 5 in association with the timing information. . After the display SpO ₂ value is fixedly displayed in step S3, or at the same time, the display control unit 44 causes the display unit 6 to display the degree of stability determined by the stability determination unit 43 (S4). When the display unit 6 performs the fixed display of the display SpO ₂ value and the display of the degree of stability, the control unit 4 causes the notification unit 9 to sound an alarm sound for notifying the operator that the fixed display has been performed ( S5).

Here, the determination procedure of the stability and the degree of stability in the stability determination unit 43 will be described with reference to FIG. First, the stability determination unit 43 calculates DS from Equation 1 based on the display SpO ₂ value calculated in the past from the present time, and compares it with a predetermined threshold Th (S21). If DS is greater than the predetermined threshold Th, the measured value is not stable, and step S21 is repeated until it is stable. If it is determined in step S21 that DS is equal to or less than the predetermined threshold Th, it is determined that the measured value is stable. Then, the process proceeds to determination of the degree of stability. First, i = 0 is set (S22), and DS is compared with B (i) which is a threshold value at each stage (S23). If it is determined that DS is larger than B (i), 1 is added to i (S24), and the process proceeds again to step S23. If it is determined in step S23 that DS is equal to or less than B (i), the display control unit 44 displays the display unit 6 so that the display unit 6 displays the degree of stability obtained from i at that time. 6 is controlled. Specifically, the display unit 6 displays “stability (10-i)” (S25). The greater the degree of stability, the higher the stability. Therefore, when DS is B (0) or less, stability 10 having the highest degree of stability is displayed. In addition, about determination of stability and the degree of stability, you may use other than the method of using the said Formula 1, as mentioned above.

  Here, the display of the display unit 6 will be described with reference to FIGS. FIG. 5 is a first image diagram for explaining the display of the display unit according to the embodiment, and FIG. 6 is a second image diagram for explaining the display of the display unit according to the embodiment. FIG. 4 is a third image diagram for explaining display on the display unit according to the embodiment;

FIG. 5 shows the display unit 6 in a state in which the display SpO ₂ value is fixedly displayed in step S3 and the degree of stability is displayed in step S4. In the display unit 6, the display 6b is a fixed display SpO ₂ value. Here, the fixed display means that the same display SpO ₂ value is continuously displayed as it is regardless of the current measurement value. More specifically, when the stability determination unit 43 determines that the SpO ₂ value is stable, the latest display SpO ₂ value currently displayed on the display unit 6 is continuously displayed ( The display control unit 44 controls the display unit 6 so that the display unit 6 is fixed. The display 6c is a display indicating that the display SpO ₂ value is fixedly displayed, and is displayed when the fixed display is started. In addition, as the display 6c, it is good also as a character like this, and it is good also as a display by a pictorial symbol etc. in addition. Moreover, in the display part 6, the display 6a is a display which shows the degree of stability. As described above, the degree of stability is calculated based on the stability when the stability determination unit 43 determines that the stability is stable, and is displayed on the display unit 6 by the display control unit 44. The display 6d is a pulse wave amplitude level meter. This is a display indicating the level of the pulse wave amplitude calculated by the analysis processing unit 42 based on the biological information obtained by the measurement unit 2, and is displayed on the display unit 6 by the display control unit 44. Specifically, it can swing up and down corresponding to the level of the pulse wave amplitude. Since the level of the pulse wave amplitude changes from time to time, it is touched up and down during the measurement. Note that the display 6d is not a display for showing a specific value, but a display indicating whether or not a measurement is being performed.

Since the display on the display unit 6 of the pulse oximeter 100 according to the present embodiment is as described above, the operator can recognize at a glance whether or not the fixed display is made by the display 6c. If the display is fixed, the displayed SpO ₂ value is a stable value and a correct measurement value. Therefore, the operator can know the correct measurement value by reading the display 6b. Further, the reliability of the displayed SpO ₂ value can be recognized by reading the stability on the display 6a. Therefore, the operator can recognize the correct SpO ₂ value and its reliability without continuing to visually check the display value from the start of measurement. That is, after the measurement is started, it may be left until an alarm sound is heard, and other work can be performed during that time. Further, whether or not the measurement operation is correctly entered can be confirmed by the display 6d.

As shown in FIG. 6, instead of the stability, the maximum value and the minimum value of the display SpO ₂ value within the determination target period may be displayed as the display 6e and the display 6f. The stability determination unit 43 obtains the maximum value and the minimum value of the display SpO ₂ value within the determination target period from the past data read from the storage unit 5. The display control unit 44 causes the display unit 6 to display the maximum value and the minimum value as the display 6e and the display 6f. The stability may be displayed together with the maximum value and the minimum value. Further, it is also possible to display the average value of the display SpO ₂ values within the alternative or together determination period of the maximum and minimum values. That is, at least one of the maximum value, the minimum value, and the average value may be displayed instead of or together with the stability. As a result, in addition to the stability, a display indicating the degree of stability is performed, and the operator can more surely know the health condition of the subject. The average value of the display SpO ₂ values may be obtained by the stability determination unit 43.

  In the display unit 6 shown in FIG. 7, the display 6g displays only one of “max” and “min” which are characters representing the maximum value and the minimum value. And what is necessary is just to display the value about the one displayed on the display 6h. The display 6g is switched alternately, and the value of the display 6h is switched accordingly. In this way, the area necessary for display can be reduced. Therefore, the display unit 6 can be reduced in size.

The measurement unit 2 of the pulse oximeter 100 continues measurement even after the fixed display is made. The analysis processing unit 42 continues to calculate the display SpO ₂ value. Each time the display SpO ₂ value is calculated, the analysis processing unit 42 takes the difference between the fixed display SpO ₂ value and the calculated latest display SpO ₂ value. (S6). That is, even if it is determined that the measurement is stable once and is fixedly displayed, the measured value may greatly change again, for example, when the state of the subject suddenly changes. In such a case, it is preferable to release the fixed display (S7), proceed to step S2 again, and determine the stability of the SpO ₂ value. Here, the predetermined value A may be a value that is too large as a variation in measurement when the SpO ₂ value is stable. Thus, when the absolute value of the difference between the display SpO ₂ value and the calculated latest display SpO ₂ value is larger than the predetermined value A, it is determined that the measured value is not stable, and step S2 is performed again. Return to, and determine whether the measured value is stable. On the other hand, when the absolute value of the difference between the display SpO ₂ value and the calculated latest display SpO ₂ value is equal to or less than the predetermined value A, the duration of the fixed display is compared with the predetermined time T ₂ ( S8). T ₂ may be set to 5 minutes, for example. If the duration of the fixed display is T ₂ or less, again the process proceeds to step S6. Also, if the duration of the fixed display is greater than T ₂ are, the power supply unit 7 stops automatically power supply. That is, the power source of the pulse oximeter 100 is automatically turned off (S9). In this way, when a fixed time (T ₂ ) has elapsed since the fixed display, the power source of the pulse oximeter 100 is automatically turned off, which has an energy saving effect. When the pulse oximeter 100 is used again after the power is automatically turned off, the display unit 6 displays the display SpO ₂ value that was fixedly displayed when the power was automatically turned off. The display control unit 44 may control the display unit 6. It should be noted that the display control unit 44 may stop the display operation of the display unit 6 when a predetermined time has elapsed after the fixed display. Further, after a fixed display, the measurement control unit 41 may stop the measurement operation of the measurement unit 2 when a predetermined time has elapsed. These have an energy saving effect.

Further, in step S2, stability judgment unit 43, if the measured value is determined not to have stable, compared with the measurement time of the predetermined time T ₁ and the pulse oximeter 100 (S10), the measurement time T When it is ₁ or less, the process proceeds to step S2. Further, if the measurement time is greater than T _1, the control unit 4 is notification section 9, even after the predetermined time (T _1), the alarm sound to inform that the measured value is not stabilized to the operator It is made to sound (S11), and it progresses to step S2 again. As described above, the pulse oximeter 100 according to the present embodiment sounds an alarm sound when the measured value is not stable even after a predetermined time has elapsed from the start of measurement. For example, the mounting state of the pulse oximeter 100 is poor. Even if there is, the operator can notice it at an early stage. Note that a timer function or the like provided in the CPU may be used to calculate the duration of fixed display and the measurement time.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

It is a figure which shows the external appearance structure of the pulse oximeter which concerns on embodiment. It is a block diagram which shows the structure of the pulse oximeter which concerns on embodiment. It is a flowchart which shows the operation | movement of the pulse oximeter which concerns on embodiment. It is a flowchart for demonstrating the procedure of stability determination and the degree determination of stability. It is a 1st image figure for demonstrating the display of the display part which concerns on embodiment. It is a 2nd image figure for demonstrating the display of the display part which concerns on embodiment. It is a 3rd image figure for demonstrating the display of the display part which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Measuring part 4 Control part 5 Storage part 6 Display part 6a-6h Display 7 Power supply part 8 Operation part 9 Notification part 16 Cable 17 Wearing belt 21 Light-emitting part 22 Light-receiving part 31 I / V conversion part 32 A / D conversion Unit 41 Measurement control unit 42 Analysis processing unit 43 Stability determination unit 44 Display control unit

Claims (6)

A measurement unit that irradiates a living body with infrared light and red light, and receives a light via the living body to obtain a biological information signal;
An analysis processing unit for analyzing the biological information signal and calculating blood oxygen saturation;
Based on the value obtained by performing the analysis process in the analysis processing unit, a stability determination unit that determines the stability of the blood oxygen saturation and the degree of stability;
A display unit for displaying the blood oxygen saturation calculated by the analysis processing unit,
When the stability determination unit determines that the blood oxygen saturation is stable, the display unit displays the blood oxygen saturation as a fixed display, and the stability determination unit determines the blood oxygen saturation. Oxygen saturation measuring device that displays the degree of stability when it is determined that is stable.   The oxygen saturation measuring device according to claim 1, wherein the degree of stability includes at least one of a maximum value, a minimum value, and an average value of blood oxygen saturation within a determination target period.   The display unit cancels the fixed display when the stability determination unit determines that the blood oxygen saturation is not stable after the display unit sets the blood oxygen saturation to the fixed display. The oxygen saturation measuring apparatus according to claim 1 or 2.   The oxygen saturation measuring apparatus according to any one of claims 1 to 3, further comprising a power supply unit that turns off the power when the duration of the fixed display is equal to or longer than a predetermined time.   The oxygen saturation measuring apparatus according to any one of claims 1 to 3, wherein when the duration of the fixed display becomes a predetermined time or longer, the display unit stops displaying.   The oxygen saturation measuring apparatus according to any one of claims 1 to 3, wherein when the duration of the fixed display is equal to or longer than a predetermined time, the measurement unit stops the measurement.

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