JP2006288835A - Simplified instrument for measuring arterial oxygen saturation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure arterial oxygen saturation SpO2 even at a low temperature. <P>SOLUTION: The instrument measures arterial oxygen saturation using the index finger. A hot insulation device 46 is arranged on the circumference of a light emitting device 36a used for measuring arterial oxygen saturation, and the temperature around the light emitting device is controlled to be within a predetermined range. This is because light emitting band characteristic of the light emitting device varies with temperature. In particular, when the temperature around the light emitting device becomes low, the band characteristic of the wavelength becomes narrow, and light having a wavelength around λa, which is the higher one between two wavelengths, is no longer emitted. As a result, arterial oxygen saturation cannot be measured. In the instrument, the light emitting device is preheated before carrying out measurement, and the temperature around the light emitting device is controlled to be within a predetermined range. By doing so, arterial oxygen saturation is measured even when the ambient temperature is low. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a portable measuring instrument for arterial blood oxygen saturation. Specifically, when measuring arterial oxygen saturation (SpO2) information noninvasively and non-invasively, the arterial oxygen saturation can now be easily and easily measured even in low-temperature areas such as cold regions and highlands. Is.

Outdoor activities such as hiking and mountain climbing, especially mountain climbing, in addition to fatigue due to walking, with ever-changing environmental changes until it adapts to high altitude, such as temperature change, atmospheric pressure change, atmospheric oxygen concentration change, A load that is not experienced in daily life is added to the living body.
These loads applied to the living body become fatigue, but there is no other way than to judge the state and degree of this fatigue.

  Under harsh environmental conditions such as mountain climbing, the experience is greatly influenced, and for beginners with little experience, it may take time to feel their physical condition change in the highland or spend time without being aware of the physical condition change In many of these cases, altitude sickness may develop or a severe overwork may occur.

  One measure for solving such a problem is to measure the arterial oxygen saturation in the blood. When this arterial blood oxygen saturation is a numerical value that may cause a change in physical condition, it would be convenient if it could be displayed or warned, and an unexpected situation could be avoided. Therefore, development of such a portable measuring instrument for arterial blood oxygen saturation is desired.

  As a living body monitoring target, a pulse oximeter is known as a device for measuring oxygen content in blood, particularly arterial blood.

  The pulse oximeter irradiates a part of the living body with light having different wavelengths, converts the intensity of reflected light or transmitted light from the living body into a photoelectric pulse wave signal (a reflected signal which is a biological signal), It is a device that measures the oxygen saturation of arterial blood from this reflected signal.

  The pulse oximeter uses the wavelength dependence of oxygen-bound hemoglobin (oxygenated hemoglobin), and uses two wavelengths, one that is easily absorbed by oxyhemoglobin and the other that is difficult to absorb. The arterial blood oxygen saturation is calculated from the intensity of the transmitted wave (transmitted light) and the reflected wave (reflected light). The arterial oxygen saturation may be determined to be 96% or more as a normal value, and below that may be determined as hypoxia. In mountain climbing and the like, as the altitude increases, the state becomes hypoxic, and the arterial oxygen saturation decreases as the temperature decreases as in a cold region.

  A pulse oximeter measures arterial blood flowing through a peripheral blood vessel. As the temperature of the peripheral blood vessel decreases, the diameter of the blood vessel decreases, and the measurement accuracy tends to decrease accordingly. Patent document 1 etc. are known as a solution for that. In Patent Document 1, a means for heating a part to be measured (for example, a finger) is employed.

JP 2004-344368 A

  By the way, the pulse oximeter disclosed in Patent Document 1 is provided with a heater for heating the finger to be examined in the arterial blood detection means (probe), and measures the temperature of the finger to be examined and the outside air temperature. By controlling the heater, the part to be measured is warmed.

  Therefore, the technique disclosed in Patent Document 1 is for controlling the living body to be inspected such as a finger to be inspected to an appropriate temperature. However, when actually measuring arterial blood oxygen saturation, the light receiving and emitting element for measuring light disposed in the arterial blood detection means, particularly when controlling the living body to be within the recommended temperature range, The stability of the operating temperature (ambient temperature) of the light emitting element is more important.

  This is because the wavelength band of light emitted from the light emitting element is different between the ambient temperature (element temperature) of the light emitting element and the low temperature range.

  When the arterial oxygen saturation is measured by the two-wavelength blood absorbance method, two wavelengths, a wavelength λa that is easily absorbed by oxyhemoglobin and a wavelength λb that is hardly absorbed by oxyhemoglobin, are used. The wavelength λa is about 800 to 830 nm, and the wavelength λb is about 600 to 670 nm. For this reason, an element in which these two wavelengths are excited simultaneously by one light emitting element is used.

  Such a light-emitting element has temperature dependence, and a curve La in FIG. 8 shows a band characteristic of a wavelength λ when excited in a normal temperature range (20 to 30 ° C.). With respect to this band characteristic, when the temperature falls below the freezing point, particularly below 10 ° C., the band characteristic at that time tends to become narrow as shown by the curve Lb in FIG. 8, and in particular, the longer wavelength λ is less likely to be excited.

  As a result, there are cases where the wavelength band characteristic becomes equal to or less than the absorption wavelength λa of oxyhemoglobin as shown by the curve Lb in FIG. If it does so, since it will become impossible to irradiate two wavelengths simultaneously to a to-be-measured site | part, it will become impossible to measure arterial oxygen saturation in a low temperature range. Therefore, even if the measuring instrument is configured so that it can be carried at a corner, it may actually become a useless long product.

  Therefore, the present invention solves such a conventional problem, and in particular, by providing a heat retaining means for the light emitting element, it can be used for a portable and simple arterial oxygen saturation that can measure the arterial oxygen saturation even in a low temperature range. A simple measuring instrument is proposed.

In order to solve the above-described problems, a simple measuring device for arterial blood oxygen saturation according to the present invention described in claim 1 includes: a light emitting element that irradiates light to be measured with different wavelengths;
A pair of light receiving elements that receive light of different wavelengths related to the oxygen saturation of arterial blood flowing through the measurement site and convert it into a biological signal;
Heat retaining means for retaining the light emitting element;
A temperature measuring element for measuring the ambient temperature of the light emitting element;
And a control unit that suppresses the ambient temperature within a predetermined temperature range based on a detection signal of the temperature measuring element.

  In this invention, the insertion recessed part of a to-be-measured site | part is provided in the side part of the measuring device main body. The measurement site is an index finger. Arterial blood detection means is provided inside the insertion recess (inner wall surface). The detection means is composed of a light emitting element that irradiates the measurement site with light having different wavelengths, and a light receiving element that converts the intensity of the reflected wave of the irradiated light from the measurement site into an electrical signal.

  When the detection means is configured to receive a pair of transmitted waves having different wavelengths, the light emitting element is disposed on the top surface side of the insertion recess and the light receiving element is disposed on the bottom surface side facing the light emitting element. A pair of light receiving elements is used so that the light receiving elements can simultaneously detect two wavelengths λa and λb (λa> λb). One wavelength λa is a wavelength that is easily absorbed by oxyhemoglobin in arterial blood, and the other wavelength λb is a wavelength that is not absorbed (difficult to be absorbed) by this oxyhemoglobin.

  The greater the amount of oxygen bound to hemoglobin, the greater the transmittance at wavelength λa. Therefore, by measuring the transmission amount (transmission intensity) at wavelength λa with reference to the transmission amount (transmission intensity) at the other wavelength λb, The arterial blood oxygen saturation can be measured. When the arterial oxygen saturation is a reference value (96% or more), “normal” is displayed, and when it is significantly insufficient (for example, 93% or less), “warning (danger)” is displayed. Display is performed, and when it is slightly less than the intermediate value, that is, the reference value (for example, about 93 to 96%), display such as “caution” is performed.

  The simple measuring instrument is used, for example, during mountain climbing in a low temperature environment. When arterial oxygen saturation is low, rest a little before resuming climbing. Thus, by displaying the arterial blood oxygen saturation in three stages, the physical condition of the subject can be easily measured and displayed.

  Among the detection means described above, a heat retaining element is provided around the light emitting element, and the ambient temperature of the light emitting element is adjusted so as to fall within a predetermined range. This is because the wavelength band characteristics of the light emitting element vary depending on the ambient temperature. When the outside air temperature is lowered, the ambient temperature is lowered accordingly, the wavelength band characteristics are narrowed, and light in the vicinity of the wavelength λa is not emitted. At that time, arterial oxygen saturation cannot be measured.

  Therefore, preheating is performed from the stage before measurement, and control is performed so that the ambient temperature of the light emitting element falls within a predetermined temperature range. This stabilizes the wavelength band characteristics and enables accurate measurement of arterial oxygen saturation even at low temperatures.

  In the present invention, when measuring the oxygen saturation of arterial blood from the intensity of a pair of light beams emitted from the light emitting elements, the ambient temperature of the light emitting elements used for irradiating the measurement site is substantially predetermined. A temperature control means is provided so as to fall within the range. As a result, the wavelength band characteristic of the light emitting element becomes narrow when the temperature is low, and the problem of not emitting light in the vicinity of one wavelength in particular can be solved.

  As described above, by preheating from the stage before measurement and controlling the ambient temperature of the light emitting element to be within a predetermined temperature range, the arterial oxygen saturation can be accurately measured even in a low temperature range.

  Since the arterial blood oxygen saturation level is simply indicated by the stage display, the current state of the arterial blood oxygen saturation level can be grasped relatively easily, which makes it easy to infer the physical condition of the subject. Have

  Subsequently, a preferred embodiment of a simple measuring device for arterial blood oxygen saturation according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a front view showing an example of a simple measuring device 10 for arterial blood oxygen saturation according to the present invention in consideration of portability. This simple arterial blood oxygen saturation measuring instrument 10 has a flat box-shaped housing (case) 12, and in one side thereof, in this example, the right finger in this example, which is a measurement site, on the upper side of the right side 12a. An insertion recess 14 for insertion is provided. On the inner surface of the insertion recess 14, arterial blood detection means 36 described later is provided.

  The front of the case is used as a display panel 12b for displaying various information. In this example, the pulse rate is measured from the detected blood flow state of arterial blood, and the measured value is displayed on the display unit 16 as a numerical value of 2 to 3 digits. An indicator lamp 18 for displaying a state in which arterial blood can be measured (measurement ready state) is attached below the pulse rate display unit 16. As the indicator lamp 18, an LED or the like can be used.

  Below the indicator lamp 18, a display unit 20 for displaying the measurement result of the arterial blood oxygen saturation is provided. Measurement results are displayed in several stages. In this example, it is displayed in three stages. For example, when the measurement result shows a normal value, “Normal” is displayed. When the value is abnormally low, “Abnormal” (or “Danger”) is displayed, and “Normal” and “Abnormal” are displayed. The display unit 20 is configured to display, for example, “caution” when the numerical value is between.

  Therefore, the display unit 20 includes three display LEDs 20a to 20c, and the display LED 20a indicating a normal value is, for example, an LED that emits green light. Hereinafter, for the same reason, a display LED 20c indicating an abnormal value is an LED that emits red light indicating a warning, and a display LED 20b that indicates an intermediate value is an LED that emits yellow light. In this example, the display LED 20a indicating a normal value is sandwiched between the display LED 20c indicating an abnormal value on the right side and the display LED 20b indicating an intermediate value on the left side.

  In the following description, when the normal value of arterial blood oxygen saturation is 96% or more when the oxygen binding amount to hemoglobin is 96% or more, the abnormal value is 93% or less, and the intermediate value is 93 to 96%.

  The display panel 12b further has a power switch (M · SW) 22 in this example, a display lamp 24 for instructing its on / off state, and a heat retention switch (PH · SW) 26 for a light emitting element to be described later, Each of the indicator lights 28 is provided. The power switch 22 and the heat retention switch 26 are independent of each other. When the heat retention switch 26 is turned on, the light emitting element 36a constituting the arterial blood detection means described later is kept within a predetermined temperature range even when the power switch 22 is turned off. Can keep warm. Therefore, when carrying in a cold district or the like, if the heat retaining switch 26 is turned on before the electronic switch 22 is turned on, measurement can be performed at any time. The electronic switch 22 may be turned on at the time of measurement.

  FIG. 2 is a schematic cross-sectional view showing the relationship between the measurement site and the arterial blood oxygen saturation detection means 36. An insertion recess 14 having a predetermined length and a predetermined diameter is provided on the right side surface 12 a side of the case 12. In this example, since the right index finger 29 is used as the measurement site, the length of the insertion recess 14 is selected as the length for inserting the index finger 29. Arterial oxygen saturation detection means 36 is attached to a predetermined position on the inner surface 32 of the insertion recess 14.

  The arterial blood oxygen saturation is measured based on the intensity of the transmitted wave or the reflected wave by simultaneously irradiating the index finger 29, which is the measurement site, with light having different wavelengths. Therefore, the detection means 36 is comprised by the light emitting element 36a for irradiating the light from which a wavelength differs, and a pair of light receiving element 36c, 38c (refer FIG. 3) which receives the transmitted wave or reflected wave. LEDs can be used as the light emitting elements 36a, and photodiodes can be used as the light receiving elements 36c and 38c.

  The embodiment shown in FIG. 2 is an example in which arterial blood oxygen saturation is measured by a transmitted wave, and therefore, a predetermined position on the top surface 14a of the inner wall surface of the insertion recess 14, that is, in this example, near the nail of the index finger 29 In addition, the light emitting element 36a is attached and fixed. For this reason, an attachment recess 34A for the light emitting element 36a is formed on the top surface 14a side, and the light emitting element 36a is attached and fixed to the light emitting element 36a on the lower surface.

  A through-hole 32 for allowing the light emitting element 36a to face the insertion recess 14 is further provided on the top surface 14a side. In order to facilitate attachment and replacement of the light emitting element 36a, a closing lid 35 is provided to close the attachment recess 34A.

The light emitted from the light emitting element 36 a passes through the inner surface (living tissue) of the index finger 29 and reaches the bottom surface 14 b side of the insertion recess 14. A mounting recess 34B is also provided on the opposed bottom surface 14b, and a pair of light receiving elements 36c and 38c are mounted and fixed thereon.
In this example, the light receiving elements 36c and 38c are attached and fixed so that the skin surface of the index finger 29 is in direct contact with the light receiving surfaces of the light receiving elements 36c and 38c.

  Of course, in order to protect the light emitting surface of the light emitting element 36a and the light receiving surfaces of the light receiving elements 36c and 38c, the upper surfaces of the through holes 32 and the mounting recesses 34B may be closed with a transparent plate such as a glass plate or a plastic plate.

  In addition, a transmission filter 36b for transmitting only light having a wavelength of about 800 to 830 nm among transmitted light is provided on the front surface of one light receiving element 36c. Therefore, the first reflected signal Sa having an intensity corresponding to the transmittance with respect to oxyhemoglobin is obtained by the one light receiving element 36c.

  In contrast, the other light receiving element 38c is also provided with a transmission filter 36b on the front surface thereof. The transmissive filter 36b is a transmissive filter for receiving only light of about 600 to 670 nm in particular from the reflected light. Therefore, a second reflected signal Sr having a transmission intensity that is not affected by oxyhemoglobin is obtained by the light receiving element 38c. This second reflected signal Sr is used as a reference signal for the transmission intensity.

  FIG. 3 is a cross-sectional view of FIG. In this example, the case 12 is composed of a front case 13a and a back case 13b formed of a plastic material or the like. The pair of light receiving elements 36c and 38c are mounted side by side.

  Among the detection means 36, the heat-retaining measure is taken especially for the light emitting element 36a. This is because when the ambient temperature (atmosphere temperature) is low, the light emitting element 36a has a property that the wavelength band characteristic becomes narrow, and the arterial oxygen saturation may not be measured due to the narrow band characteristic. An example of the heat retaining means 40 for that purpose is shown in FIG.

  The heat retaining means 40 has a flat heat insulating case 42 having a substantially rectangular parallelepiped shape, and a light emitting element 36a is attached and fixed at a substantially central portion in the heat insulating case 42. At this time, the light emitting element 36 a is attached so that the tip end (outgoing surface) 48 protrudes slightly from the heat insulating case 42. The emission surface 48 of the light emitting element 36a has a spherical shape so that the emitted light has a certain extent.

  The inside of the heat insulating case 42 is filled with a heat insulating material 44 such as a resin, a metal material, or a silicon elastomer, and a heat insulating element plate 52 is attached so as to penetrate substantially the middle part of the heat insulating case 42 to the left and right.

  The heat retaining element 50 functions as a preheater (PH). Therefore, as shown in FIG. 5, a through-hole 54 through which the light-emitting element 36a passes is provided in the substantially central portion of the heat-retaining element plate 52, and a film-like shape is formed on the upper surface of the heat-retaining element plate 52, so A surface heater (conductive layer) 56 is attached. The formation pattern of the surface heater 56 shown in FIG. 5 is an example.

  Since the surface heater 56 generates heat by energizing between the terminals 56a and 56b of the surface heater 56, the entire light emitting element 36a is heated. Thus, the light emitting element 36a is adjusted to have an appropriate temperature. In this example, the temperature is controlled to be 20 to 30 ° C. In order to perform this temperature control, the temperature measuring element 46 is in a position close to the light emitting element 36a and is not directly affected by the surface heater 56, for example, away from the surface heater 56 as shown in FIG. However, the temperature measuring element 46 is provided at a position close to the light emitting element 36a. As the temperature measuring element 46, a thermocouple, a temperature resistance element, a thermistor, or the like can be used. The example of FIG. 4 is a case where a thermistor is used, and this temperature measuring element 46 is attached and fixed to the heat retaining element plate 52.

  By providing such a heat retaining function, the ambient temperature of the light emitting element 36a can be kept at an appropriate temperature state by preheating even in a place where the temperature is very low, such as a cold place or a high place. Therefore, the arterial oxygen saturation can be measured without being affected by the outside air temperature.

  FIG. 6 is a system diagram of a main part showing an example of a measurement display circuit 60 having a control system mounted on the simple measuring instrument 10 for arterial blood oxygen saturation according to the present invention.

  By driving the light emitting element 36a, light is emitted to the index finger 29 as a measurement site. The band characteristic of the light is a curve La in FIG. The transmitted light of the light irradiated to the index finger 29 is received by the pair of light receiving elements 36c and 38c after the band is limited by the pair of transmission filters 36b and 38b. The intensity of the reflected light to the other light receiving element 38c is supplied to the control unit 70 as the second reflected signal Sr, and the intensity of the reflected light to the one light receiving element 36c is supplied to the control unit 70 as the first reflected signal Sa. To be supplied.

  In the control unit 70, the pulse is measured using the input first and second reflected signals Sa and Sr, and the measured value is displayed on the pulse display unit 16.

  The second reflected signal Sr described above is not affected by oxyhemoglobin, but the first reflected signal Sa is affected by oxyhemoglobin. Therefore, the transmission intensity of the first reflected signal Sa with respect to the second reflected signal Sr is increased. Based on this, the arterial oxygen saturation SpO2 is calculated.

  The arterial oxygen saturation is displayed in three stages. When the value is normal, the display LED 20a is turned on. When it is an abnormal value, the display LED 20c is lit. And when it is those intermediate values, LED20b for a display will light. Therefore, the subject can grasp the “normal”, “abnormal”, and “caution” states based on the display colors of the display units 20a to 20c.

  For example, when the result measured during climbing to Takayama is `` Caution '', it is thought that oxygen will be deficient in the future, so by taking sufficient rest, slowing the walking speed, etc. You can maintain your physical condition.

  In the case of “abnormal” display, it is necessary to climb carefully while receiving sufficient advice from experienced persons, such as stopping climbing or lightening luggage. It is because it can be said that it is in the condition where it is easy to develop altitude sickness. Thus, by measuring the arterial blood oxygen saturation, it is possible to easily know a sign that the physical condition is liable to be lost at the stage before complaining of a malfunction. The same applies to measurements in cold regions.

  In this example, in addition to the three-stage display of arterial oxygen saturation, a voice message output unit 72 is provided. A voice message is output in accordance with the three-stage display.

  For example, if the measurement result is “normal”, a voice message “normal” is output. When the measurement result is “abnormal”, a voice message such as “Dangerous due to lack of oxygen. Please receive advice from the surroundings” is output.

  When the measurement result is an intermediate value between them, a voice message such as “Be careful because oxygen is scarce” is output to alert the subject and accompanying person. Can do.

  Incidentally, the measurement display circuit 60 is basically battery-driven, and a battery (primary or secondary battery) is used as the power source 62. The power switch 22 supplies a voltage from the power source 62 as a driving voltage to the control unit 70, the light emitting element 36a, the light receiving elements 36c, 38c, and the like configured by the CPU.

  The power supply voltage is further supplied to the surface heater 56 via the heat retention switch 26. From the time when the heat retention switch 26 is turned on until the proper temperature (measurement ready state) is reached, the measurable display LED 18 blinks as will be described later, and is lit when the proper temperature is reached.

  The ambient temperature of the light emitting element 36 a is detected by the temperature measuring element 46, and the detection signal is supplied to the control unit 70. Until the ambient temperature of the light emitting element 36a reaches an appropriate temperature, the switching means 64 is controlled to be turned on by a temperature control signal from the control unit 70, and energization to the surface heater 56 (energization for preheating) is continued.

  After reaching the proper temperature state, by controlling the switching means 64, the energization to the surface heater 56 is intermittently controlled so as to be in the heat retaining state. As described above, the temperature when the temperature is kept is set to, for example, a temperature of about 25 ° C. among 20 to 30 ° C. This temperature range is not a strict value, and even if it is 20 ° C. or lower as described above, it is not a temperature that cannot be used, but it is preferable to set the recommended temperature of the device manufacturer as an appropriate temperature. Therefore, it can be said that 20 to 30 ° C. is an ideal temperature control range.

  Until the ambient temperature of the light emitting element 36a reaches an appropriate temperature, the measurable display LED 18 is controlled to be blinking as described above. When the temperature reaches an appropriate temperature and the temperature is kept, the LED 18 for measurement is controlled so as to be always lit. When the heat retention switch 26 is off, the LED 18 and the indicator light 28 of the heat retention switch 26 are not lit.

  FIG. 7 is a flowchart showing a measurement result display process example, in particular, of the control by the control unit 70 described above.

  First, it is determined whether or not the ambient temperature of the light emitting element 36a is in an appropriate temperature range. When the temperature is not raised to the appropriate temperature range, the LED 18 that displays the measurement possible state is blinked to indicate that it is in the measurement standby state. (Steps 81 and 82). When the temperature is within the appropriate temperature range, the LED 18 is switched from the blinking state to the lighting state (step 83).

  When the ambient temperature of the light emitting element 36a reaches an appropriate temperature, the first and second reflected signals Sa and Sr are taken at every predetermined timing, the pulse is measured, and the value is displayed on the display unit 16 (step 84). Subsequently, the arterial blood oxygen saturation is measured from the first and second reflection signals Sa and Sr taken at the same timing (step 85).

  As a result of the measurement of arterial oxygen saturation, it is determined whether or not the value is normal (step 86). First, when it is determined that the arterial blood oxygen saturation is within the normal range, the display LED 20a is turned on and displayed in green to inform the subject that the measurement result is normal. (Step 87). At the same time, a voice message is output to output that the arterial oxygen saturation is within the normal range (step 88). By this visual and auditory notification, the measurement result is definitely notified to the subject.

  When it is determined that the arterial oxygen saturation is within the range of the abnormal value, the display LED 20c is turned on and displayed in red, thereby notifying the subject that the measurement result indicates the abnormal value. (Step 91). At the same time, a voice message is output to output that the arterial oxygen saturation is an abnormal value (step 92), and the user is urged to refrain from acting or to act carefully. This can prevent the onset of altitude sickness and the like.

  When it is determined that the arterial blood oxygen saturation is between the normal value and the abnormal value, the display LED 20b is turned on (yellow), and a small amount of oxygen is notified by a voice message (step 89). , 90).

  The above display processing and voice message output processing are continued until the power source 62 is turned off, in other words, only while the reflected signals Sa and Sr are obtained, and this series of processing ends when the power source 62 is turned off ( Step 93).

  In the first embodiment described above, the detection means 36 is exemplified by a transmission type detection means. In addition, the detection means 36 can be configured as a reflection type. In that case, a light emitting element 36a and a pair of light receiving elements 36c and 38c are provided on the bottom surface 14b side shown in FIG. 2, and the index finger 29, which is a measurement site, is irradiated with light having different wavelengths, and reflected light from the artery. Is received, and the arterial oxygen saturation is measured. The rest of the configuration is the same as that of the first embodiment, and the description thereof is omitted.

  The present invention can be applied to a simple measuring instrument that simply measures arterial oxygen saturation and displays the state in several stages.

It is a front view which shows an example of the simple measuring device for arterial blood oxygen saturation which concerns on this invention. It is the one part longitudinal cross-sectional view. FIG. It is sectional drawing which shows an example of a heat retention means. It is a top view which shows an example of a heat retention element. It is a principal part systematic diagram of the measurement display circuit applicable to this invention. It is a flowchart which shows the example of control of a measurement display circuit. It is a curve figure which shows the wavelength band characteristic of a light emitting element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Simple measuring instrument 12 for arterial blood oxygen saturation ... Case 14 ... Insertion recessed part 16 ... Pulse display part 18 ... Measurement possible display part 20 ... Display part 22 ... Power switch 26 ... thermal insulation switch 36 ... detection means 36a ... light emitting element 36c, 38c ... light receiving element 40 ... thermal insulation means 50 ... thermal insulation element 56 ... surface heater 46 ... temperature measurement Element 70 ... control unit 72 ... voice message display unit

Claims (9)

A light-emitting element that irradiates light of different wavelengths to the measurement site;
A pair of light receiving elements that receive light of different wavelengths related to the oxygen saturation of arterial blood flowing through the measurement site and convert it into a biological signal;
Heat retaining means for retaining the light emitting element;
A temperature measuring element for measuring the ambient temperature of the light emitting element;
A simple measuring device for arterial blood oxygen saturation, comprising: a control unit that suppresses the ambient temperature within a predetermined temperature range based on a detection signal of the temperature measuring element. 2. The simple measuring instrument for arterial blood oxygen saturation according to claim 1, wherein the heat retaining means is housed in the heat insulating case with its irradiation surface protruding from the heat insulating case. The heat insulation case is filled with a heat conductive material,
The simple measuring device for arterial blood oxygen saturation according to claim 2, wherein a heat retaining element and the temperature measuring element are accommodated. 4. The simple measuring device for arterial oxygen saturation according to claim 3, wherein a film-shaped surface heater is used as the heat retaining element. 2. The simple measuring instrument for arterial blood oxygen saturation according to claim 1, wherein any one of a thermistor, a thermocouple, and a temperature resistance element is used as the temperature measuring element. A display part for the measurement result of the arterial oxygen saturation is further provided,
The simple measuring device for arterial blood oxygen saturation according to claim 1, wherein the display unit displays the measurement result according to a normal value or an abnormal value. A voice message means of the measurement result of the arterial oxygen saturation is further provided,
2. The simple measuring device for arterial oxygen saturation according to claim 1, wherein the voice message means outputs a measurement result corresponding to a normal value and an abnormal value. 7. A simple measuring device for arterial oxygen saturation according to claim 6, wherein said measurement result display section and voice message means for outputting the measurement result by voice are provided. 2. The simple measuring instrument for arterial blood oxygen saturation according to claim 1, wherein the light received by the pair of light receiving elements is transmitted light transmitted through the measurement site.

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