JP2975741B2 - Peripheral circulation status detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus capable of detecting a peripheral circulation state of a living body.

[0002]

2. Description of the Related Art Since the color or temperature of the skin of a living body reflects the state of peripheral circulation, the skin or the skin of the patient is regularly examined to determine whether there is a shock condition such as a sudden drop in blood pressure during the operation. Anesthesiologists and the like perform sensory examination of color and temperature of limbs. However, such a method is intuitive, requires skill and varies at the same time, and it takes a long time to judge using a measured value by a sphygmomanometer.

On the other hand, reflected light from the skin obtained by using a reflection type pulse wave meter (press simograph, for example, US Pat. No. 3,679,974) originally designed for measuring the pulse rate is used. It is conceivable to detect the peripheral circulatory state based on the change, that is, the change in the volume pulse wave. Since the vascular network in the dermis below the epidermis contracts in relation to the occurrence of a shock state, the shock state of the living body is determined based on the decrease in the magnitude of the plethysmogram. is there.

[0004]

By the way, in the above-mentioned reflection type pulse wave meter, reflected light of light emitted from the light emitting element toward the skin is detected by a light receiving element arranged at a fixed interval from the light emitting element. When a plethysmogram signal is obtained and a shock state of a living body is detected based on a change in the magnitude of the plethysmogram signal, other factors such as a change in air temperature, a change in irradiation light, and a mental state of the patient. Therefore, the shock pulse state of the living body could not be accurately determined because the volume pulse wave signal also changed. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a peripheral circulatory state detecting device capable of accurately detecting a shock state of a living body.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the gist of the present invention is to provide a peripheral circulating state for detecting a peripheral circulating state of a living body, as shown in the claim correspondence diagram of FIG. A detection device, comprising: (a) a reflection-type pulse wave detection means including at least two pairs of light-emitting elements and light-receiving elements, which are arranged so as to face the skin of the living body and have different intervals from each other; Attenuation coefficient calculating means for calculating respective attenuation coefficients from the intensities of the first reflected light and the second reflected light from the light emitting element detected by the respective elements;
(c) peripheral circulation state determining means for determining the peripheral circulation state of the living body based on the attenuation coefficient ratio calculated by the attenuation coefficient calculating means.

[0006]

With this arrangement, at least two pairs of the light-emitting element and the light-receiving element have different intervals in the reflection-type pulse wave detecting means, so that the light-receiving element is located at a different depth from the epidermis of the living body. The first reflected light and the second reflected light are respectively received. The attenuation coefficient is calculated from the intensities of the first reflected light and the second reflected light by the attenuation coefficient calculation means, and the peripheral circulation state is determined by the peripheral circulation state determination means based on the attenuation ratio.

[0007]

Here, the attenuation ratio calculated from the intensity of the first reflected light and the intensity of the second reflected light by the attenuation coefficient calculating means is the value of the main reflection position of the first reflected light and the second reflected light. It corresponds to the degree of light absorption and scattering, ie the blood volume. For this reason, the ratio of the light attenuation coefficient at different depth positions from the display indicates the relative difference in blood volume at those different depth positions, and changes in air temperature, irradiation light, and patient It is not affected by factors that change the blood volume at different depth positions, such as mental states. Therefore, according to the present invention, even if both the first reflected light and the second reflected light change due to other factors such as a change in temperature, a change in irradiation light, and a mental state of the patient, the ratio of the attenuation coefficient is not affected. However, since the attenuation ratio changes due to the occurrence of vasoconstriction from the peripheral side that occurs when the living body is in a shock state, the shock state of the living body can be accurately determined.

[0008]

A second aspect of the present invention is directed to a peripheral circulatory state detector for detecting a peripheral circulatory state of a living body, as shown in the claim correspondence diagram of FIG. An apparatus, (a) a reflection-type pulse wave detection means including at least two pairs of light-emitting elements and light-receiving elements, which are arranged so as to face the skin of the living body and have different intervals from each other,
(b) attenuation coefficient calculating means for calculating respective attenuation coefficients from the intensities of the first reflected light and the second reflected light from the light emitting element detected by the light receiving element, and (c) the attenuation coefficient calculating means. And means for displaying a change in the ratio of the calculated attenuation coefficient.

[0009]

With this arrangement, at least two pairs of the light-emitting element and the light-receiving element have different intervals in the reflection-type pulse wave detecting means, so that the light-receiving element is located at a different depth from the epidermis of the living body. The first reflected light and the second reflected light are respectively received. The attenuation coefficient is calculated from the intensity of the first reflected light and the intensity of the second reflected light by the attenuation coefficient calculation means, and the change in the attenuation ratio is displayed by the attenuation coefficient ratio display means.

[0010]

Therefore, according to the present invention, it is also possible to accurately determine the shock state of a living body based on the change over time of the attenuation ratio displayed by the attenuation coefficient display means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 3, the reflection type pulse wave sensor 1
Numeral 0 is mounted on the skin 12 of the living body by a fixing means (not shown) such as a band or a double-sided adhesive sheet. The reflection type pulse wave sensor 10 includes a sensor main body 14 having a concave portion on the contact surface of the skin 12, and light emitting chips 16 sequentially arranged at predetermined intervals in the concave portion of the sensor main body 14 so as to correspond to the skin 12. , The first light receiving chip 18,
The second light receiving chip 20 and the third light receiving chip 22, and the first light shielding wall 24 disposed between the light emitting chip 16, the first light receiving chip 18, the second light receiving chip 20, and the third light receiving chip 22, respectively. , The second shading wall 26, and the third
The light shielding wall 28 and the transparent resin 30 filling the space between the light shielding walls 28
And the light emitting chip 1 reflected in the skin 12
6 from the first light receiving chip 18 and the second light receiving chip 2
0 and the third light receiving chip 22 respectively. In this embodiment, the light emitting chip 16 and the first
Between the light receiving chip 18, the second light receiving chip 20, and the third light receiving chip 22, three pairs of light emitting chips and light receiving chips are substantially arranged.

The skin 12 has a thickness of about 0.1 to 0.3 mm and has a keratinous epidermis 32 and a subcutaneous skin below the epidermis 32.
The dermis 34 is composed of a dermis 34 having a thickness of about 3 to 2.4 mm and a fat-filled subcutaneous tissue 36 located under the dermis 34. Generally, the border between the dermis 34 and the subcutaneous tissue 36 is not clear. The artery forms a network of arteries at the boundary between the subcutaneous tissue 36 and the dermis 34 and in the dermis 34, enters the nipple as capillaries, bends like a snare, and moves to the vein. The veins form a network of veins within the dermis 34 and at the border between the dermis 34 and the subcutaneous tissue 36, some into deep veins along arteries and some into cutaneous veins. As shown in FIG. 3, reflected light from the inside of the skin 32 shown at a point A in FIG.
The reflected light from the inside of the dermis 34 indicated by a dot is
The light-emitting chip 16, the first light-receiving chip 18, the second light-receiving chip 20, and the third light-receiving chip so that the reflected light from the subcutaneous tissue 36 shown at the point C in FIG. 22 and the first light shielding wall 2
4. The shapes and positions of the second light shielding wall 26 and the third light shielding wall 28 are determined.

The light-emitting chip 16 has a wavelength that is apt to be scattered by red blood cells in blood, for example, red light or infrared light having a wavelength of 660 nm or more, especially a band that is hardly changed by blood oxygen saturation.
That is, the LED chip outputs infrared light of about 805 nm. The first light receiving chip 18 and the second light receiving chip 2
0 and the third light receiving chip 22 are, for example, well-known photodiode chips or phototransistor chips.

The light emitting chip 16 includes an arithmetic and control unit 40
The light is emitted by the drive current supplied from the drive circuit 44 in accordance with the command signal from the output port 42. Signals output from the first light receiving chip 18, the second light receiving chip 20, and the third light receiving chip 22 respectively pass through an amplifier (not shown), a multiplexer 46, and an A / D converter 48 to the CPU 50 of the arithmetic and control unit 40. Supplied. The arithmetic and control unit 40 processes the input signal according to a program stored in the ROM 54 in advance while using the temporary storage function of the RAM 52, and causes the display 56 to display the arithmetic result and the like.

The operation of the arithmetic and control unit 40 will be described with reference to the flowchart of FIG. Step S1 in FIG.
In this case, the light emitting chip 16 is turned on, and the signals output from the first light receiving chip 18, the second light receiving chip 20, and the third light receiving chip 22 are read. In the following step S2, the read signals, that is, the reflected light intensity I _R1 received by the first light receiving chip 18, the reflected light intensity I _R2 received by the second light receiving chip 20, and the light received by the third light receiving chip 22 Based on the reflected light intensity I _R3 obtained,
From Equations 1, 2, and 3 shown below,
2 of attenuation coefficients K _1, the attenuation coefficient K _2, and the attenuation coefficient K ₃ of the subcutaneous tissue 36 of the dermis 34 is calculated. In Expressions 1, 2, and 3, I ₀ is the irradiation light intensity of the light emitting chip 16 and a predetermined constant value is adopted.

[0016]

## EQU1 ## K ₁ = I _R1 / I ₀

[0017]

K ₂ = (I _R2 / I ₀ ) / (I _R1 / I ₀ ) ²

[0018]

K ₃ = (I _R3 / I ₀ ) (I _R1 / I ₀ ) ² / (I _R2 / I ₀ ) ²

In step S3 of FIG. 4, the ratio K ₂ / K ₃ of the attenuation coefficient K ₂ of the dermis 34 and the attenuation coefficient K ₃ of the subcutaneous tissue 36 obtained from the above equations 2 and ₃ is calculated. Next, at step S4, the above-mentioned damping coefficient ratio K ₂ /
K predetermined time before _3, the amount of change from the value before several seconds for example Δ
R is calculated, and the peripheral circulation state is determined based on the change amount ΔR from the relationship shown in FIG. 5, for example. In step S5, the trend of the actual attenuation coefficients K ₁ , K ₂ , K ₃ and the ratio K ₂ / K ₃ of the attenuation coefficient, and the determination result in step S4 are displayed on the display 56.

FIG. 6 shows a display example of the display 56. In the figure, a trend of attenuation coefficient K ₁ , K ₂ , K ₃ and a ratio of attenuation coefficient K ₂ / K ₃ is displayed at trend display location 58, and an abnormal display of peripheral circulation occurs at abnormal display location 60. Displayed with time. In addition, the mark “時点” indicates the time point of determination of peripheral circulation.

As described above, according to the present embodiment, in the reflection-type pulse wave sensor 10, the light emitting chip 16 and the light receiving chip 20 and the light emitting chip 16 and the light receiving chip 22 have different distances from each other. The chip 20 and the light receiving chip 22 have different depth positions from the surface of the skin 12.
The first reflected light and the second reflected light from points B and C are received, respectively. The intensity I of the first reflected light and the second reflected light is determined by step S2 corresponding to the attenuation coefficient calculating means.
_The damping ratio K ₂ / K ₃ is calculated based on _R2 and I _R3 , and a step S corresponding to the peripheral circulation state determining means is performed.
4, the peripheral circulation state is determined based on the change amount ΔR of the attenuation ratio, and the determination result is displayed at the abnormal display location 60. Step S5 corresponding to the attenuation coefficient ratio display means.
In variation width W of the damping ratio K ₂ / K ₃ by the damping ratio K ₂ / K ₃ is displayed trend, that is, the change amount from the starting point of the change is displayed.

Here, the attenuation ratio K calculated from the intensities I _R2 and I _{R3 of} the first reflected light and the second reflected light, respectively.
₂ / K ₃ corresponds to the degree of absorption and scattering of light at the main reflection position of the first reflected light and the second reflected light, that is, the blood volume. For this reason, 2 different depth positions from the surface
Light attenuation coefficients K ₂ and K at points B and C
The ratio K ₂ / K ₃ of ₃ represents the relative difference in blood volume in their point B and point C, changes in temperature, changes in illumination light, different depth positions, such as mental state of the patient location Are not affected by the factors that together change the blood volume.
Therefore, according to the embodiment, even if both the first reflected light and the second reflected light change due to other factors such as a change in temperature, a change in irradiation light, and a mental state of the patient, the ratio of the attenuation coefficient is not affected. However, since the attenuation ratio changes due to the occurrence of vasoconstriction from the peripheral side that occurs when the living body is in a shock state, the result is displayed by viewing the determination result displayed at the abnormal display location 60 or at the trend display location 58 by attenuation ratio K ₂ / K ₃ variation width W is displayed, it is possible to accurately determine the shock of a living body.

Next, another embodiment of the present invention will be described. In the following description, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The pulse wave sensor 70 in the embodiment of FIG. 7 includes a first light-emitting chip 72, a second light-emitting chip 74, and a third light-emitting chip 76 that output light having the same wavelength as the light-emitting chip 16, and the light emitted from them. A common light receiving chip 78 for receiving the reflected light, and three first light shielding walls 80 provided between the first light emitting chip 72, the second light emitting chip 74, the third light emitting chip 76, and the light receiving chip 78, respectively. , A second light-shielding wall 82, and a third light-shielding wall 84. As in the previous embodiment, the reflected light from inside the epidermis 32 shown at point A in FIG. 7, the reflected light from inside the dermis 34 shown at point B in FIG. 7, and the inside of the subcutaneous tissue 36 shown at point C in FIG. The first light-emitting chip 72, the second light-emitting chip 74, the third light-emitting chip 76, and the light-receiving chip 7 so that the reflected light
8, the first light shielding wall 80 and the second light shielding wall 8
The shape and position of the second and third light shielding walls 84 are determined.

The driving circuit 86 of the present embodiment includes the first light emitting chip 72, the second light emitting chip 74, and the third light emitting chip 76.
The drive current is sequentially output in accordance with a command signal from the arithmetic and control unit 40 in order to perform time-division driving for sequentially and selectively emitting light. Therefore, the light receiving chip 78 sequentially receives three types of reflected light having different depth positions, and a signal representing the intensity of the three types of reflected light is supplied to an amplifier (not shown) and A / A
The data is input to the CPU 50 via the D converter 48. By the same operation as in the above-described embodiment, the display shown in FIG. 6 is obtained on the display 56, and the same effect as in the above-described embodiment is obtained.

In this embodiment, the first light emitting chip 72, the second light emitting chip 74, and the third light emitting chip 76
, The intensity of the reflected light of the irradiating light received by the light receiving chip 78 is represented by I ₀₁ , I ₀₂ , and I _{o3.
Let R1} , _IR2 and _IR3 be the epidermis 32, dermis 34,
And the attenuation coefficients K ₁ , K ₂ and K of the subcutaneous tissue 36
₃ is calculated from Equations 4, 5, and 6 shown below.

[0026]

## EQU4 ## K ₁ = I ₀₁ / I _R1

[0027]

K ₂ = (I ₀₂ / I _R2 ) / (I ₀₁ / I _R1 ) ²

[0028]

K ₃ = (I ₀₃ / I _R3 ) (I ₀₁ / I _R1 ) ² / (I ₀₂ / I _R2 ) ²

The embodiment shown in FIG.
It is provided with a pair of light emitting chip and light receiving chip.
In the figure, a pulse wave sensor 90 includes a first light emitting chip 92 and a second light emitting chip 92 that output light of the same wavelength as the light emitting chip 16.
A light-emitting chip 94, a common light-receiving chip 96 for receiving reflected light of light emitted therefrom, and the first light-emitting chip 9
2, a first light-shielding wall 98 and a second light-shielding wall 100 provided between the second light-emitting chip 94 and the light-receiving chip 96, respectively. In this embodiment, as shown at a point B ′ in FIG. 8, the reflected light from inside the dermis 34 or the epidermis 32 and the dermis 34, and as shown at a point C ′ in FIG. The first light-emitting chip 92, the second light-emitting chip 94, the arrangement position of the light-receiving chip 96, and the first light-shielding wall 9 so that the reflected light from the tissue 36 is received by the common light-receiving chip 96.
8 and the shape and position of the second light shielding wall 100 are determined.

In this embodiment, the irradiation light intensity of the first light emitting chip 92 and the second light emitting chip 94 is I ₀₁ ′,
_{Assuming that} I ₀₂ ′ and the reflected light intensities of the irradiation light received by the light receiving chip 96 are I _R1 ′ and I _R2 ′, the attenuation coefficients K ₁ ′ and K ₂ ′ at different depths in the skin 12 are as follows. The attenuation coefficient ratio K ₁ ′ / K ₂ ′ is calculated from Equations 7 and 8 shown below. Also in this embodiment,
Similarly, the display shown in FIG.

[0031]

K ₁ '= (I ₀₁ ' / I _R1 ')

[0032]

K ₂ ′ = (I ₀₂ ′ / I _R2 ′) / (I ₀₁ ′ / I _R1 ′) ²

While the embodiment of the present invention has been described with reference to the drawings, the present invention can be applied to other embodiments. For example, in the above-described embodiment, by providing the common light emitting chip 16 or the light receiving chip 78, three pairs of the light emitting chip and the light receiving chip having a relationship different from each other are constituted by four elements. The pulse wave sensor 10 or 70 may be constituted by three pairs of the chip and the light receiving chip and composed of a total of six elements.

The ratio of the damping coefficient in the above-described embodiment is K
₂ / K ₃ that have been defined but no problem even K ₃ / K _2.

Further, in the above-described embodiment, the change amount ΔR or the change width W of the damping coefficient ratio may be numerically displayed on the display 56, or the ratio of the damping coefficient K ₂ / K _{3 in} the trend may be displayed. The inclination may be calculated, and the inclination value of the trend may be displayed.

In step S4 described above, the determination is made in two stages, that is, the normal range or the abnormal range of the peripheral circulation, based on the variation ΔR of the attenuation coefficient ratio. May be done.

Further, in the above-described embodiment, the description is made such that the reflected light intensity I _R3 obtained by the light receiving element having the largest distance from the light emitting element is the reflected light from the point C in the subcutaneous tissue 36. However, it is not always necessary to be inside the subcutaneous tissue 36. In short, any reflected light from a depth position different from point B may be used.

Further, in the above-described embodiment, in order to obtain reflected light from different depth positions, the distance between the light emitting element and the light receiving element forming a pair is arranged so as to be different from each other, and a light shielding wall is provided therebetween. 24, 26, 28, 80, 82, 84
Are provided, but these light shielding walls are not necessarily required. That is, for example, in U.S. Pat. No. 4,867,557 (Japanese Patent Application No. 62-87468), column 5, line 7 to line 30
Photon diffusion theory (Photon Diffution T
This is because, as shown in heory), the depth of the light path through which the light passes through the skin is different due to the difference between the light emitting element and the light receiving element.

The above is merely an example of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to the claims of the first invention.

FIG. 2 is a diagram corresponding to claims of the second invention.

FIG. 3 is a diagram illustrating the configuration of an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a control operation of the arithmetic and control unit in FIG. 3;

FIG. 5 is a diagram showing a relationship used for peripheral circulation abnormality determination in the operation shown in FIG. 4;

6 is a diagram showing a display example displayed on a display by the operation shown in FIG. 4;

FIG. 7 is a diagram corresponding to FIG. 3, showing another embodiment of the present invention.

FIG. 8 is a diagram corresponding to FIG. 3, showing another embodiment of the present invention.

[Explanation of symbols]

 10, 70 reflection type pulse wave sensor 16 light emitting chip (light emitting element) 18 first light receiving chip (light receiving element) 20 second light receiving chip (light receiving element) 22 third light receiving chip (light receiving element) 72 first light emitting chip (light emitting element) 74 Second light emitting chip (light emitting element) 76 Third light emitting chip (light emitting element) Step S2 Damping coefficient calculating means Step S4 Peripheral circulation state determining means Step S5 Damping coefficient ratio displaying means

Claims (2)

(57) [Claims] 1. A peripheral circulatory state detecting device for detecting a peripheral circulatory state of a living body, comprising at least two pairs of light-emitting elements and light-receiving elements which are arranged so as to face the skin of the living body and have different mutual intervals. Reflection pulse wave detection means; attenuation coefficient calculation means for calculating respective attenuation coefficients from the intensities of the first reflected light and the second reflected light from the light emitting element detected by the light receiving element, respectively; A peripheral circulatory state determining device for determining the peripheral circulatory state of the living body based on the attenuation coefficient ratio calculated by the means. 2. A peripheral circulatory state detecting device for detecting a peripheral circulatory state of a living body, comprising at least two pairs of light emitting elements and light receiving elements which are arranged to face the skin of the living body and have different intervals. Reflection pulse wave detection means; attenuation coefficient calculation means for calculating respective attenuation coefficients from the intensities of the first reflected light and the second reflected light from the light emitting element detected by the light receiving element, respectively; And a damping coefficient ratio display means for displaying a change in the ratio of the damping coefficients calculated by the means.