JP2013220312A - Pulse oximeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse oximeter which is turned to a ring type in order to improve a fit property of a finger and is capable of finger recognition even under sunlight.SOLUTION: In a pulse oximeter 1 including a measuring device body 3 which stores a power source 80 and a control board loaded with an electronic circuit driven by the power source 80 and has a display part 2 for displaying information processed by the electronic circuit, and a detection part 4 mounted on the measuring device body 3, the detection part 4 includes: a light emitting side arm 5 which extends from the measuring device body 3 to one side and brings a light emitting means 6 into contact with one side part of a finger of a subject; a light receiving side arm 7 which extends from the measuring device body 3 to the other side and brings a light receiving means 8 into contact with the other side of the finger of the subject; and belt parts 9 and 10 which extend from one of the light emitting side arm 5 and the light receiving side arm 7 to the other side, for fixing the measuring device body 3 to the root of the finger of the subject or a second finger joint part.

Description

  The present invention relates to a pulse oximeter that is attached to a finger of a subject and detects blood oxygen saturation and the like.

  The blood measurement device disclosed in Patent Document 1 is a blood measurement device (pulse oximeter) that optically measures hemoglobin in arterial blood, and includes first test light (infrared light) having a first wavelength and second light. Light incident means for injecting intensity-modulated first inspection light (red light) having a wavelength and second incident light toward an artery in a living body (finger), and a first wavelength of light emitted from outside the living body. Detection means for detecting the first inspection light and the second inspection light having the second wavelength, and calculating oxygen saturation of hemoglobin based on the first inspection light and the second inspection light, and the first inspection light or the second inspection light. To calculate the optical path length change between arterial dilation and arterial contraction based on the transfer change between arterial dilation and arterial contraction, and to calculate the hemoglobin concentration based on the oxygen saturation and the optical path length change Means (data processor).

  A pulse oximeter probe disclosed in Patent Document 2 includes a first housing and a second housing that are mounted so that a light emitting element and a light receiving element face each other. The second housing is configured to be adapted to abut the side of the fingertip by bending the second housing continuously to the first housing so as to cover the toe portion of the finger. The lead wire for connecting with the probe connector is inserted and arranged at the end of the housing.

JP 2004-194908 A JP 2007-54594 A

  As is apparent from the above-mentioned patent documents, the conventional method for optically measuring fingertip pulse waves is to transmit light to the fingernail portion of the fingertip without bone, but it is attached to the fingertip. For this reason, there arises a problem that the wearability is poor.

  Conventionally, as a finger recognition method, there is a light receiving / emitting portion in a structure in which external light is relatively blocked. Therefore, when there is no finger, the directly emitted light reaches the light receiving element, so the amount of received light is small. When there are many fingers, the light received from the light receiving element is blocked by the finger and the amount of light received decreases, so it was possible to recognize the wearing of the finger, but it was exposed to direct sunlight under sunlight. Under such circumstances, there was a problem that finger recognition was not possible because the sunlight was strong even when a finger was inserted.

  For this reason, the present invention is to provide a pulse oximeter that is of a ring type in order to improve the wearability of the finger and can recognize the finger even in sunlight.

  Accordingly, the invention of the present application accommodates a control board on which a power supply and an electronic circuit driven by the power supply are mounted, and a measuring instrument body including a display unit for displaying information processed by the electronic circuit, and the measuring instrument body In the pulse oximeter constituted by a detection unit attached to the light emitting side arm, the detection unit extends from the measuring device main body to one side and makes the light emitting means contact one side of a subject's finger A light receiving side arm that extends from the measuring instrument body to the other side and contacts the light receiving means to the other side of the subject's finger, and extends from one of the light emitting side arm or the light receiving side arm to the other side. The measuring device main body is constituted by a belt portion for fixing the measurement device main body to the fingertip or the second finger joint portion of the subject's finger. In particular, the light emitting means is an LED light source having two wavelengths of infrared and red, and the light receiving means is a light receiving element having two wavelengths of infrared and red.

  Further, it is desirable that the light receiving means is disposed at a position shifted by a predetermined angle from a position facing the light emitting means with the finger of the subject to be worn as a center. The range of deviation is desirably ± 90 ° from the position facing the light emitting means.

  Furthermore, it is preferable that the light receiving unit detects the amount of external light by natural light and increases the amount of light emitted by the light emitting unit to be greater than the amount of external light.

  Further, the light emitting means is caused to emit light every predetermined time. When the amount of light received by the light receiving means is small, it is determined that the finger is inserted, and when the amount of received light is large, it is determined that the finger is not inserted. Measurement is preferably started when it is determined that a finger is inserted, and measurement is preferably turned off when it is determined that a finger is not inserted.

  Further, the power source is a secondary battery built in the main body, and charges the secondary battery with power supplied from a charger. Since the voltage supplied to the secondary battery rises, if it recognizes that the voltage (charging monitoring voltage) has risen, it stops the measurement function, and when charging is completed and separated from the charger, the voltage Since (charge monitoring voltage) decreases, it is desirable to detect the decrease and validate the measurement function.

  Therefore, according to the present invention, the pulse oximeter can be mounted on the fingertip or the second finger joint part of the subject's finger like a ring, and the light emitting means and the light receiving means are opposed to each other with the fingers interposed therebetween. Since they are arranged away from each other, light containing finger plethysmogram waves can be received avoiding the bones of the fingers, so that it is possible to continue the measurement in a normally worn state, unlike the conventional case.

  Furthermore, since finger insertion can be reliably detected even under external light such as natural light, it can be always worn and measured.

FIG. 1 is a perspective view of a pulse oximeter according to the present invention. FIG. 2 is a front view of the pulse oximeter according to the present invention. FIG. 3 is a front view of the pulse oximeter with the band portion opened. FIG. 4 is a schematic configuration diagram of a pulse oximeter according to the present invention. FIG. 5 is a flowchart of control executed in the pulse oximeter.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 to 3, a pulse oximeter 1 according to an embodiment of the present invention includes a measuring instrument body 3 having a display unit 2 made of liquid crystal on a side surface, and a detection provided at the lower part of the measuring instrument body 3. Part 4.

  The detection unit 4 extends from the measuring device body 3 to one side and makes the light emitting unit 6 contact the one side of the subject's finger, and from the measuring device body 3 to the other side. A light receiving side arm 7 that extends and contacts the light receiving unit 8 on the other side of the finger of the subject, and extends from one side of the light emitting side arm 5 or the light receiving side arm 7 to the other side, and the measuring device body 3 is It is comprised by the belt part for fixing to the finger root or 2nd finger joint part of a test subject's finger.

  The belt portion of the present embodiment is constituted by a first belt portion 9 extending along the light receiving side arm 7 and a second belt portion 10 extending along the light emitting side arm 5, One part 11 constituting the hook-and-loop fastener is fixed to the front end of one belt part 9, and the other part 12 constituting the hook-and-loop fastener is fixed to the second belt part 10 and the first belt part. 9 and the parts 11 and 12 of the second belt portion 10 are bonded to each other, whereby the pulse oximeter 1 is attached to the fingertip or the second joint portion of the subject.

  In addition, the first and second belt portions 9 and 10 are preferably elastic resin plates formed in an arc shape.

  The light emitting unit 6 is composed of an infrared light LED and a red light LED, and the light receiving unit 8 is composed of a light receiving element. Furthermore, it is desirable that the light receiving unit 8 is disposed at a position shifted from the position facing the light emitting unit 6 across the finger. In this embodiment, the light emitting section 6 and the light receiving section 8 are preferably arranged at a predetermined center angle α (90 ° to 150 °), and in this embodiment, they are arranged at a center angle of 120 °. Is.

  Further, in the measuring instrument main body 3 of the pulse oximeter 1, there is a secondary battery 80 that is charged in a state of being mounted on a charger (not shown), and a control unit that performs measurement work using the secondary battery 80 as a power source. 40, a transmission unit 20 for controlling the light emitting unit 6 by a signal from the control unit 40, a reception unit 30 for receiving a signal received by the light receiving unit 8 and transmitting it to the control unit 40, and a calculation by the control unit 40 At least the display unit 2 for displaying the result and the antenna unit 50 for transmitting the result calculated by the control unit 40. In addition, the control unit 40 includes at least a calculation unit 42 that processes signals and a storage unit 41 that stores measurement values calculated by the calculation unit 42.

  The data transmitted by the antenna unit 50 is transmitted to the receiving device 70 disposed near the subject via the antenna unit 60 and processed and stored.

  The measurement work performed in the pulse oximeter 1 having the above configuration is, for example, shown in the flowchart of FIG. Further, when the pulse oximeter 1 is placed on a charger (not shown) and charging of the secondary battery 10 is started, the charge monitoring voltage rises. Therefore, the rise of the charge monitoring voltage is detected to detect the pulse oximeter 1. Stop the measurement function at. Further, when charging is completed and the pulse oximeter 1 is separated from the charger, the charge monitoring voltage is lowered, so that the measurement function started from step 100 is enabled by detecting the decrease in the charging monitoring voltage. To do.

  In the measurement operation started from step 100, the finger insertion recognition process is first executed. In this finger recognition process, the infrared LED of the light emitting unit 6 is caused to emit light (step 110), and the infrared light is received by the light receiving unit 8 (step 120). Then, in step 130, the amount of infrared light received by the light receiving unit 8 is determined. Since it is clear that there is no obstacle, it is determined that the finger has not been inserted (step 140). Further, in the determination of step 130, it is clear that an obstacle (finger) exists between the light emitting unit 6 and the light receiving unit 8 when the received light amount is small (when the attenuation is large with respect to the emitted light amount). Since there is, finger insertion is determined (step 200).

  If it is determined in step 140 that a finger has not been inserted, the measurement function is stopped (measurement OFF) in step 150, and it is determined in step 160 whether or not a predetermined time (β seconds) has elapsed. Then, the light receiving unit 8 detects the amount of received light without causing the light emitting unit 6 to emit light, and detects this as the external light level. If the external light level is larger than the amount of received light when the light emitting unit 6 is caused to emit light in step 180, the process proceeds to step 190 to increase the light emission amount of the light emitting unit 6 to be larger than the external light level ( In step 190), the process returns to step 110, and the finger recognition process is executed every predetermined time.

  If it is determined in step 200 that the finger is inserted, the infrared LED of the light emitting unit 6 is caused to emit light for a predetermined time in step 210, and the infrared light is received in the light receiving unit 8 in step 220. In step 230, the red LED of the light emitting unit 6 is caused to emit light for a predetermined time, and in step 240, the light receiving unit 8 receives red light.

  The measurement principle of the pulse oximeter 1 is that a two-wavelength LED light source of infrared light and red light is irradiated transcutaneously, and the ratio is calculated based on the difference in the absorption spectrum of oxyhemoglobin and reduced hemoglobin. The saturation% Sp02 is obtained. Basically, oxyhemoglobin does not absorb red light very much and absorbs infrared light strongly, and reduced hemoglobin does not absorb much infrared light and absorbs red light strongly. It can be seen that the amount of oxygenated hemoglobin is large when the amount of reduced hemoglobin is large and the pulsation of infrared light is large. For this reason, if there is much red light, oxygen saturation will be low, and if there is much infrared light, oxygen saturation will be high.

  Therefore, first, at step 250, the absorbance is detected. This absorbance is the difference between the bottom (diastolic) and peak (systolic) waveform of one pulse wave waveform as the AC (alternating current) component, the value obtained when each LED is extinguished as the DC component, The ratio of the AC component is detected as the relative absorbance of each wavelength.

  Further, in step 260, the oxygen saturation% Sp02 is measured by the relational expression represented by% SpO2 = f (r) · R / Ir. In this relational expression, R is a pulse wave amplitude due to red light, Ir is a pulse wave amplitude due to infrared light, and F (r) is oxygen saturation based on a ratio r / Ir of red light and infrared light. It is a function to determine% SpO2.

  Furthermore, in step 270, the peak interval of each pulse wave by infrared light is obtained and converted to a heart rate per minute, and the pulse rate of the subject is measured.

  In step 280, the measurement is started and recorded in the storage unit 41 every time the measurement value is updated. Further, in step 290, an appropriate measurement result (air oxygen saturation and pulse rate) is telemetry transmitted as binary data every time the measurement value is updated. When transmission is completed, all data may be erased.

  As described above, in the pulse oximeter 1 of the present invention, the ring type can be attached to the subject's finger root or the second finger joint, and the light emitting portion and the light receiving portion are opposed to each other with the finger interposed therebetween. Since it is arranged at a position displaced from the finger, it can be detected by optically measuring the finger plethysmogram while avoiding the bone of the finger even if it is worn on the finger.

  Further, since the light emission amount of the light emitting unit is adjusted according to the external light level, finger insertion recognition can be reliably performed.

DESCRIPTION OF SYMBOLS 1 Pulse oximeter 2 Display part 3 Measuring device main body 4 Detection part 5 Light emission side arm 6 Light emission part 7 Light reception side arm 8 Light reception part 9 1st belt part 10 2nd belt part 80 Power supply

Claims (4)

A measuring instrument body that houses a control board on which a power source and an electronic circuit driven by the power source are mounted, and that displays information processed by the electronic circuit, and a detection unit that is mounted on the measuring instrument body In a pulse oximeter composed of
The detector includes a light emitting side arm that extends from the measuring instrument main body to one side and contacts light emitting means to one side of the subject's finger, and extends from the measuring instrument main body to the other side of the subject. A light receiving side arm for contacting the light receiving means to the other side of the finger, and extending from one side of the light emitting side arm or the light receiving side arm to the other side so that the measuring device body is a finger base or a second finger of the subject's finger A pulse oximeter comprising a belt portion for fixing to a joint portion.   2. The pulse oximeter according to claim 1, wherein the light receiving means is arranged at a position deviated by a predetermined angle from a position facing the light emitting means with a finger of a subject to be worn as a center.   3. The pulse oximeter according to claim 1, wherein the light receiving unit detects an external light amount by natural light, and increases an emitted light amount by the light emitting unit to be greater than the external light amount.   The light emitting means is caused to emit light every predetermined time. When the amount of light received by the light receiving means is small, it is determined that the finger is inserted. When the amount of received light is large, it is determined that the finger is not inserted, and the finger is inserted. The pulse according to any one of claims 1 to 3, wherein the measurement is started when it is determined that the finger is not detected, and the measurement is turned off when it is determined that the finger is not inserted. Oximeter.

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