JPH1094527A - Bloodstream data measuring apparatus and rheometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the bloodstream of a limited tissue as desired. SOLUTION: A light emitting surface of a light emitting part 3a at a photodetecting means 3 and a photodetecting surface of a photodetecting part 3b are close contacted with a tissue of a living being and a logarithmic conversion part 4a of a bloodstream data detection means 4 is given an output V(t) of the photodetecting part 3b and a set value V0 to output log V0/V(t)}. An amplifying part 4b of a bloodstream data detection means 4 multiplies the output by 680/(ε.da.a.b)}. The values in the parenthesis are previously determined as follows: ε represents a molar extinction coefficient at an isosbestic point, da an average optical path length to the photodetecting surface from the light emitting surface in the tissue of the living being, (a) the concentration of hemoglobin of blood and (b) the density of the tissue. Thus, the amount of bloodstream can be obtained by determining changes in the output of the bloodstream data detection means 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring data on blood volume of a living tissue and blood flow.

[0002]

2. Description of the Related Art Conventionally, there is a venous occlusion method as a method for measuring a blood flow in a living body. This measurement is performed, for example, as follows. First, mercury or the like is put into a thin silicon tube, electrodes are attached to both ends, and a resistor, a so-called rubber strain gauge, is wound around a finger, a foot, an arm, or the like. A circuit is formed by using the rubber lane gauge as one side of the bridge by, for example, a Wheatstone bridge. Next, when the central side of the wound part is compressed with a cuff at a pressure of about 40 to 50 mmHg, the vein is compressed and blood from the artery is accumulated in the tissue. For this reason, the area around which the rubber lane gauge is wound becomes thick, and the tube of the gauge extends, so that the resistance value increases as shown in FIG.
This change in the resistance value is plotted on a graph, the maximum slope of the rise is obtained, and the blood flow is obtained from the slope by a constant calculation.

[0003]

However, when the measurement is performed by such a method, an average tissue blood flow of a finger, a foot, or an arm including all skin, muscles, and nerves is obtained. However, it is not possible to determine the blood flow of each limited tissue such as skin, muscle, nerve, and the like.
The present invention has been made in view of such a conventional drawback, and an object of the present invention is to provide a device capable of determining a desired limited tissue blood flow.

[0004]

According to a first aspect of the present invention, there is provided a blood volume data measuring apparatus comprising: a light emitting portion having a light emitting surface which is in close contact with a living tissue; and a light receiving surface which is in close contact with the living tissue. A light detecting unit having a light receiving unit that converts the received light into an electric signal, and a length da of an average optical path in the living tissue from a light emitting surface of the light emitting unit to a light receiving surface of the light receiving unit; Around the average optical path in the living tissue based on the value determined in advance with reference to each value of the blood hemoglobin concentration a and the density b of the living tissue, and the output of the light receiving unit of the light detecting means. And a blood volume data detecting means for obtaining data relating to the blood volume.

According to a second aspect of the present invention, in the first aspect, the light emitting surface of the light emitting portion and the light receiving surface of the light receiving portion are oriented in the same direction.

The device according to claim 3 is the device according to claim 1 or 2
In the apparatus described above, the light detecting means is means for generating light of one wavelength whose light emitting portion is equally absorbing to both oxygenated hemoglobin and reduced hemoglobin, and the blood volume data detecting means Is a logarithmic conversion unit that calculates log (V0 / V) from the output value V of the light receiving unit and the set value V0, and multiplies the output of this logarithmic conversion unit by α / (da ・ a ・ b) (α; constant) And an amplifying unit.

According to a fourth aspect of the present invention, in the device according to any one of the first to third aspects, the light detecting means is means for emitting light of two wavelengths, and the light quantity detecting means is a blood volume data detecting means. Is obtained from two output values VA, VB and two set values VA0, VB0 of the light receiving section corresponding to the two types of wavelengths A, B.
g (VA0 / VA), log (VB0 / VB) logarithmic converter and two outputs of this logarithmic converter are βA / (daA · a · b)
The sum of the two outputs of this amplifier and the amplifier that doubles, βB / (daB · a · b) times (βA, βB; constant, daA, daB; da for each of the wavelengths A and B) An adder is provided.

According to a fifth aspect of the present invention, there is provided a blood flow meter having a light emitting portion having a light emitting surface closely contacted with a living tissue, and a light receiving surface closely contacted with the living tissue, and converting the light received by the light receiving surface into an electric signal. A light-detecting unit having a light-receiving unit for conversion; an average optical path length da in the living tissue from a light-emitting surface of the light-emitting unit to a light-receiving surface of the light-receiving unit; and a hemoglobin concentration of blood of the living body.
a and a value determined in advance with reference to each value of the density b of the living tissue, and data on the blood volume around the average optical path in the living tissue based on the output of the light receiving unit of the light detection means. And a data processing means for calculating a blood flow rate around a portion where the light emitting surface and the light receiving surface are attached from a change in data relating to the blood volume detected by the blood volume data detecting device. .

A blood flow meter according to a sixth aspect is characterized in that, in the blood flow meter according to the fifth aspect, the light emitting surface of the light emitting unit and the light receiving surface of the light receiving unit are oriented in the same direction.

In a blood flow meter according to a seventh aspect of the present invention, in the blood flow meter according to the fifth or sixth aspect, the light detecting means has a light-emitting portion which is equally absorbed with respect to both oxygenated hemoglobin and reduced hemoglobin. The blood volume data detecting means includes a logarithmic converter for calculating log (V0 / V) from the output value V of the light receiving unit and the set value V0, and a logarithmic converter for calculating the log (V0 / V). And an amplifier for multiplying the output of the unit by α / (da · a · b) (α; a constant).

[0011] The blood flow meter according to claim 8 is the fifth to seventh embodiments.
In any of the blood flow meters described above, the light detecting unit is a unit whose light emitting unit generates light of two wavelengths, and the blood volume data detecting unit is a light receiving unit corresponding to the two wavelengths A and B. From the two output values VA, VB and two set values VA0, VB0, a logarithmic converter that calculates log (VA0 / VA) and log (VB0 / VB), and two outputs of the logarithmic converter βA / (daA
a ・ b) times, βB / (daB ・ a ・ b) times (βA, βB; constant, daA, d
aB; an amplifier for performing da) for each of the wavelengths A and B, and an adder for summing two outputs of the amplifier.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the first embodiment of the present invention will be described. FIG. 2 shows the light absorption characteristics of oxygenated hemoglobin and reduced hemoglobin in blood. As shown in this figure, both have characteristic patterns and intersect at some points. These points are called isosbestic points, and the extinction coefficients of oxygenated hemoglobin and reduced hemoglobin are equal at light at the wavelength of this isosbestic point, for example, λ2.

As shown in FIG. 3, the light having the wavelength of the isosbestic point and having the intensity I0 is applied to the point (a) on the tissue surface of the living body. In tissue, light is strongly scattered by cells and the like, and the straightness is completely lost. Let I (t) be the intensity of light received at point (b), which is d away from the point (a) on the tissue surface. Absorbance of the whole tissue as A (t), of which Absorbance by blood Ab
(t) If the absorbance of only the tissue excluding blood is Ar, the following equation holds according to Lambert-Beer's law. A (t) = log {I0 / I (t)} = Ab (t) + Ar (1)

As shown in FIG. 3, the light incident from the tissue surface is scattered in the tissue and travels on average on the average optical path length to reach (b) at a distance d from the point of incidence on average. The average optical path length is da [cm], and the molar extinction coefficient at the isosbestic point is ε.
[L / (cm · mM)] (L; liter, the same applies hereinafter), and the sum of oxygenated hemoglobin and reduced hemoglobin, that is, the concentration per tissue of total hemoglobin (the amount of hemoglobin per unit tissue) is represented by C (t) [g / L], the expression (1) is expressed as follows. A (t) = log {I0 / I (t)} = ε · C (t) · da + Ar (2)

It has been clarified by Wray et al. That the average optical path length da in a living tissue has a certain relationship with the distance d between the incident point on the tissue surface and the measurement point (Biochimica B).
iophysica Acta 933 (1988) pages 184-192). That is,
da = c ・ d (c; constant), so if d is known,
da can be easily sought. If equation (2) is solved for C (t), the following is obtained. C (t) = {1 / (ε ・ da)} ・ A (t)-{1 / (ε ・ da)} ・ Ar (3)

By dividing C (t) by the hemoglobin concentration a [g / dL] of the blood, the blood volume in the tissue (blood volume per unit tissue) can be obtained. The molecular weight of hemoglobin is 6800
Since it is 0, 1 [mM] is 68 g. The density of the tissue is b [g /
mL], equation (3) becomes as follows. C (t) / (a ・ b) = {680 / (ε ・ da ・ a ・ b)} ・ A (t)-{680 / (ε ・ da ・ a ・ b)} ・ Ar [mL / 100g] (4)

Equation (4) represents the amount of blood per 100 g of tissue. Here, the first term on the right side of equation (4) is {680 / (ε · da
・ A ・ b)} ・ A (t) = F (t) is measured. The apparatus used for this measurement is as follows.

First, this apparatus comprises a light detecting means 3 and a blood volume data detecting means 4 as shown in FIG. A light-emitting unit 3a having a light-emitting surface disposed so as to be in close contact with the living tissue and emitting light having a wavelength of equi-absorption to both oxygenated hemoglobin and reduced hemoglobin; And a light receiving unit 3b that has a light receiving surface disposed so as to be in close contact with the light receiving unit 3b and converts given light into an electric signal.

In the blood volume data detecting means 4, an electric signal V0 corresponding to the intensity I0 of the light emitted from the light emitting section 3a is preset, and this V0 and the intensity I (t) of the light received by the light receiving section 3b are set. Log {V0 / V (t)} from the sensor output V (t) corresponding to the logarithmic conversion unit 4a, and log {V0
/ V (t)} by {680 / (ε · da · a · b)}. log {V0 / V (T)} = log {I0 / I (t)}, and (2)
Since A (t) = log {I0 / I (t)} as shown in the equation, the output of the blood volume data detecting means 4 is F (t) = {680 /
(ε ・ da ・ a ・ b)} ・ A (t).

With this apparatus, F (t) is continuously measured, and the result is recorded. In this case, the cuff is wrapped around the central part from the measurement site, and after the start of the measurement, congestion is caused in a portion including the measurement site. At this time, the blood volume data detecting means 4
Are as shown in FIG. From equation (4), F (t) = C (t) / (a · b) + {680 / (ε · da · a · b)} · Ar (5), and C (t) / (a B) is the blood volume per 100 g of tissue as described above, and Ar is considered to be constant for a short time,
The change in F (t) is the change in blood volume per 100 g of tissue.
Therefore, if the maximum slope of the rise of F (t) is obtained after the start of congestion, that value is the blood flow per unit time. For the sake of explanation, the value of V0 is a value corresponding to the intensity I0 of the light emitted from the light emitting unit, but finally, F (t) = k ·
log {V0 / V (t)}, that is, the change of F (t) = klogV0-klogV (t) is observed, so the value of V0 corresponds to the intensity I0 of the light emitted from the light emitting part. The value does not have to be a value, and if it is a constant value, an appropriate value that makes it easy to observe the graph may be used.

As a method of obtaining the maximum slope of the rise from the graph of F (t), first, a straight line portion at the time of the rise is obtained on the graph, and if the slope of the straight line is obtained, the blood flow is obtained.

That is, this rising portion is represented by a straight line F1 (t) =
Assuming that Bt + D (B, D; constant), from equation (5), C (t) / (a · b) = Bt + D + {680 / (ε · da · a · b)} · Ar Therefore, the amount of change per unit time of the blood volume C (t) / (a · b) per 100 g of tissue is B 2. Therefore, if B is determined, its value is the blood flow.

As another method, as shown in FIG.
If the approximate straight line F1 (t) is drawn on the graph of (t), from equation (5), {C (t2) -C (t1)} / {(a · b) · (t2-t1)} = {F1 (t2) -F1 (t1)} /
(t2-t1), the difference between the values F1 (t2) and F1 (t1) at two points on the straight line and 2
By determining the difference t2-t1 at the time, the blood flow can be determined.

An apparatus created based on the above principle will be described. As shown in FIG. 5, this device comprises a blood volume data measuring device 1 and a data processing device 2. The blood volume data measuring device 1 includes a light detecting unit 3 and a blood volume data detecting unit 4.
Consisting of The light detecting means 3 includes a sensor 7 including a light emitting optical fiber 5a, a light receiving optical fiber 5b, and a holding portion 6 for holding the distal end surfaces thereof in the same direction in the same direction. A laser module 8 for supplying a laser beam having an isosbestic point wavelength of 810 nm to oxygenated hemoglobin and reduced hemoglobin at one end of the light emitting optical fiber 5a.
A driving circuit 9 for driving the laser module 8;
A photodiode 10 for converting light from one end of the light receiving optical fiber 5b of the sensor 7 into a current, and a current / voltage converter 11 for converting an output of the photodiode 10 into a voltage
And an amplifier 12 for amplifying the output of the current / voltage converter 11. The light detecting means 3 and the blood volume data detecting means 4 excluding the sensor 7 are integrated and housed in one housing.

The blood volume data detecting means 4 obtains log {10V1 / V (t)} from the output V (t) of the amplifier 12 and the set voltage V1, and outputs the log {10V1 / V (t)}. A voltage setting unit 13a for providing a set voltage V1;
And an amplifier 14 for amplifying the output of. log amplifier 1
10 in the output log {10V1 / V (t)} of 3 is to be 1 [V] when V1 = V (t). log amplifier 13
And a voltage setting unit 13a correspond to the logarithmic conversion unit 4a shown in FIG. 1, and the amplifier 14 corresponds to the amplification unit 4b shown in FIG.

The amplifier 14 has a function of adjusting the amplification factor by operation. The amplifier 14 has a distance between the tip of the light emitting optical fiber 5a and the light receiving optical fiber 5b of the sensor 7 (strictly speaking, the distance between the centers of the tip surfaces). ) D, the amplification rate is 68 according to the value of the hemoglobin concentration a of the subject's blood and the density b of the tissue.
It is set to be 0 / (ε · da · a · b) times.
Here, da = 4.3d (see the above-mentioned Wray article) is used.

The data processing device 2 has an A / D converter 1 for converting the output of the blood volume data detecting means 4 into a digital signal.
6 and a digital computer 17 for processing the output signal of the A / D converter 16. The digital computer 17 has an input interface 18 for receiving a signal from the A / D converter 16, a ROM 19 in which a processing program and data necessary for the processing are written, and data necessary for the processing. RAM 20 that is rarely or read out, CPU that performs data processing based on a program written in ROM 19 and general control of each unit
21, a display controller 22, a printer controller 23, a keyboard controller 24 controlled by the CPU 21, and these controllers 22, 23, 24
25, printer 26, keyboard 2 controlled by
7 The ROM 19 stores a program as shown in FIG.

Next, a description will be given of a case where the blood flow of the subject is measured by using the apparatus configured as described above. As shown in FIG. 7, the blood volume data measuring device 1 is used for this measurement.
A cuff 31 and an air supply / exhaust device 32 for supplying / exhausting air to / from the cuff 31 are prepared in addition to the data processor 2 and the data processor 2. In the figure, reference numeral 33 denotes an air supply / exhaust changeover switch, reference numeral 34 denotes a display section of a pressure gauge, reference numeral 35 denotes a power switch, and reference numeral 36 denotes a pressure control knob.

First, the operator sets the voltage V1 of the log amplifier 13
Is set, and the position of the output of the blood volume data detecting means 4 is determined.

Next, as shown in FIG. 7, the operator wraps the cuff 31 around the center of the measurement site of the subject. In this case, if the measurement site is the fingertip of the hand, the cuff 31 is wrapped around the arm,
The sensor 7 is attached to the fingertip. Next, the operator operates the air supply / exhaust device 32 to set the internal pressure of the cuff 31 to 40 to 50 mmHg. As a result, the veins are compressed, and the peripheral side becomes congested.

Thus, the blood volume data detecting means 4 outputs the same blood volume data as that shown in FIG. This blood volume data is provided to the digital computer 17 via the A / D converter 16. The processing performed by the CPU 21 of the digital computer 17 will be described with reference to the flowchart of FIG.

First, blood volume data given from the A / D converter 16 is taken in for a predetermined time and stored in the RAM 20 (step 101). Next, the blood volume data F shown in FIG.
From the relationship between (t) and t, an equation of a straight line having a maximum gradient at the time of rising is obtained (step 102). Next, the inclination value of the straight line is displayed on the display unit 25 and printed by the printer 26 (step 103). This slope value is the blood flow to be obtained.

In the present embodiment, the apparatus performs the process up to obtaining the blood flow. However, the output of the blood volume data measuring device 1 is recorded by a recorder or a computer, and the data of the blood volume is analyzed by a person to start up. A straight line of time may be obtained, and the blood flow may be obtained from this.

In this case, the values F1 (t2), F1 at two points on the straight line
(F1 (t2) -F1
(t1)} / (t2-t1) can be calculated to determine the blood flow. If the difference t2-t1 at the two time points is taken as 1 minute, F1 (t2) -F1
The blood flow per minute can be obtained only by obtaining (t1).

As the sensor 7, optical fibers 5a, 5b
A light-guiding type was used. However, if the distance between the light-emitting surface and the light-receiving surface can be long, the same effect can be obtained even if a light-emitting device such as an LED and a photodiode are directly provided on the sensor. The effect is obtained.

In the present embodiment, since the light emitting surface and the light receiving surface are arranged on the same side of the measurement site, it is only necessary that a part of the surface of the target biological tissue appears. It is not necessary to take out so that the surroundings appear. For this reason, pain and damage to the subject can be reduced. On the other hand, if the periphery of the tissue to be measured is present, as shown in FIG.
a and 41b so that the tip surfaces of the holding members 42a and 41b face each other.
May be used. Also in this case, the average optical path length is da = 4.3d.

Next, a second embodiment will be described. First, the principle will be described. As shown in the absorption characteristics of oxygenated hemoglobin and reduced hemoglobin in FIG. 2, the measurement is performed using light of two different wavelengths λ1, λ3 different from the isosbestic point wavelength λ2. In this case, the following equation is established in the same manner as the above equation (2). A ₁ (t) = log {I0 ₁ / I ₁ (t)} = ε _{x 1} · C _x (t) · da ₁ + ε _{y 1} · C _y (t) · da ₁ + Ar ₁ (6) A _{3 (t) = log {I0} 3 / I 3 (t)} = ε x 3 · C x (t) · da 3 + ε y 3 · C y (t) · da 3 + Ar 3 (7)

Here, A ₁ (t); absorbance of the whole tissue in the light of wavelength λ _{1 I} 0 ₁ ; intensity of light of the wavelength λ 1 irradiated on the tissue surface I ₁ (t); linear distance d from the irradiation point Intensity of light of wavelength λ1 on a distant tissue surface ε _{x 1} ; molar extinction coefficient of oxygenated hemoglobin at light of wavelength λ1 C _x (t); concentration of oxygenated hemoglobin per tissue (oxygenation per unit tissue) hemoglobin) da _1; mean path length in the tissue of light of wavelength λ1 ε _{y 1;} molar extinction coefficient of reduced hemoglobin at light wavelength λ1 C _y (t); per concentration (unit organizations per tissue deoxyhemoglobin Amount of reduced hemoglobin) Ar ₁ ; Absorbance of only tissue excluding blood in light of wavelength λ1 A ₃ (t); Absorbance of whole tissue in light of wavelength λ3 I0 ₃ ; Intensity of light of wavelength λ3 irradiated on tissue surface is I ₃ (t); on the tissue surface apart linear distance d from the irradiation point Kicking the light of wavelength [lambda] 3 strength epsilon _{x 3;} the reduced hemoglobin at light wavelength [lambda] 3; mean path length epsilon _{y 3} of the light of wavelength [lambda] 3 within the tissue; wavelength [lambda] 3 oxygenation molar extinction coefficient da ₃ of hemoglobin in the light Molar extinction coefficient Ar ₃ ; Absorbance of tissue excluding blood at light of wavelength λ3

From equations (6) and (7), C _x (t), C
_y (t), the sum of them, C _T (t) = C _x (t) + C _y (t) (8) If C _T (t) is obtained, this C _T (t) is the concentration of total hemoglobin per tissue ( (Total amount of hemoglobin per unit tissue). If the hemoglobin concentration of blood (weight per unit volume) is a and the density of tissue is b, C _T (t) / (a · b) = {C _x (t) + C _y (t)} / (a · b) (9) represents the amount of blood per unit volume of tissue.

From the equations (6), (7), (8) and (9), the following equation is established. C _T (t) / (a · b) = K1 A ₁ (t) + K2 A ₃ (t) + K3Ar ₁ + K4Ar ₃ (10) where K1, K2, K3, and K4 are a, b , da ₁ , da ₃
Is a constant determined by Two wavelengths λ1, λ3
Can be regarded as da ₁ = da ₃ = da, so that K1, K2, K3, and K4 are as follows, respectively. K1 = (ε _{y 3} -ε _{x 3} ) / {(a ・ b) ・ (ε _{x 1}・ ε _{y 3} -ε _{x 3}・ ε _{y 1} ) ・ da} (10A) K2 =-(ε _{y 1-} ε _{x 1} ) / {(a ・ b) ・ (ε _{x 1}・ ε _{y 3} -ε _{x 3}・ ε _{y 1} ) ・ da} (10B) K3 =-(ε _{y 3} -ε _{x 3} ) / {( a ・ b) ・ (ε _{x 1}・ ε _{y 3} -ε _{x 3}・ ε _{y 1} ) ・ da} (10C) K4 = (ε _{y 1} −ε _{x 1} ) / {(a ・ b) ・ (ε _{x 1 · ε y 3 - ε x} 3 · ε y 1) · da} is denoted by (10D) (10) of the right side of the equation _{K1 a 1 (t) + K2} a 3 (t) and f (t). That is, the _{f (t) = K1 A 1} (t) + K2 A 3 (t) (11), A 1 (t), by measuring A ₃ (t) is determined the curve of f (t). A ₁ (t) and A ₃ (t) measure log {I0 ₁ / I ₁ (t)} and log {I0 ₃ / I ₃ (t)} as shown in equations (6) and (7). Then you can ask. That is,

The search of f (t) = K1 · log {I0 1 / I 1 (t)} + K2 · log {I0 3 / I 3 (t)} (12), a curve of f (t). At this time, blood pressure is applied to the central part of the living tissue from the measurement site, thereby causing congestion. Due to this congestion, the curve of f (t) rises sharply. If a straight line having the maximum slope at the time of rising is obtained, the slope of this straight line is the blood flow to be obtained. Because this line is f1 (t) = Et + F (E, F; constant), the equation (10) becomes
C _T (t) / (a ・ b) = Et + F + K3Ar ₁ + K4Ar ₃ , K3Ar ₁ + K
4Ar ₃ can be considered constant in the short term, so C
_{This is because T} (t) / (a · b) is a straight line having a slope of E, and the change in blood volume per unit time is E.

Next, an apparatus based on such a principle will be described. As shown in FIG. 9, the apparatus comprises a blood volume data measuring device 51 and a data processing device 52. The blood volume data measuring device 51 includes a light detecting unit 53 and a blood volume data detecting unit 54. The light detecting means 53 includes a holding unit 5 that holds the light emitting optical fiber 55a and the light receiving optical fiber 55b so that their tip surfaces face the same direction on the same surface.
And two wavelengths λ 1, which are different from the isosbestic point wavelength for oxygenated hemoglobin and reduced hemoglobin at one end of the light emitting optical fiber 55 a of the sensor 57.
a laser module 58 capable of selectively supplying a laser beam of .lambda.3, a drive circuit 59 for driving the laser module 58, and a light receiving optical fiber 55 of a sensor 57.
photodiode 6 for converting light from one end of b into a current
0, a current / voltage converter 61 for converting the output of the photodiode 60 into a voltage, and a current / voltage converter 61
The multiplexer 62 for distributing the output of the laser module 58 and the laser module 58 so that the laser beams of the wavelengths λ1 and λ3 are generated alternately, and further, the output of the photodiode 60 is distributed according to the generation timing of each laser beam. It comprises a drive circuit 59 and a control circuit 63 for outputting a timing signal to the multiplexer 62.

The blood volume data detecting means 54 obtains log {VA0 / VA (t)} from one output VA (t) of the multiplexer 62 (corresponding to the light of the wavelength λ1) and the set voltage VA0 and outputs it. The log amplifier 64 and the set voltage VA
0, an amplifier 65 for amplifying the output of the log amplifier 64, and the other output VB (t) of the multiplexer 62 (corresponding to light of wavelength λ3) and the set voltage VB0.
A log amplifier 66 that obtains log {VB0 / VB (t)} and outputs it
A voltage setting unit 66a for applying the set voltage VB0 to the log amplifier 66; an amplifier 67 for amplifying the output of the log amplifier 66; and an adder 68 for adding the outputs of the amplifiers 65 and 67.
Consisting of

The amplifiers 65 and 67 have a function of adjusting the amplification factor by operation. The distance between the tip of the light emitting optical fiber 55a and the light receiving optical fiber 55b of the sensor 57 (strictly speaking, the distance between the center of the tip surface and the center of the sensor 57). Distance) d and the values of the hemoglobin concentration a of the subject's blood and the density b of the tissue, the respective amplification rates are K1 times and (1
0B) is set to be K2 times as shown in the equation.
Here, da = 4.3d (see the above-mentioned Wray article) is used.

The data processing device 52 has the same configuration as the data processing device 2 shown in the first embodiment.

Next, the operation of the above-configured device will be described. The mode of use of this device is the same as in the first embodiment. That is, the operator attaches the sensor 57 to the measurement site of the subject and presses the central side from the installation site to cause congestion. At this time, the laser module 58
, Light having wavelengths λ1 and λ3 is generated alternately and emitted from the sensor 57 to the living tissue. On the other hand, light from the living tissue is received by the photodiode 60 and converted into electric current. This current is converted into a voltage by the current / voltage converter 61.
The output of the current / voltage converter 61 reaches a multiplexer 62, where it is divided into a signal corresponding to the light of wavelength λ1 and a signal corresponding to the light of wavelength λ3 under the control of the control circuit 63. The respective signals reach amplifiers 65 and 67, where they are multiplied by K1 and K2. The outputs of the amplifiers 65 and 67 are added by an adder 69. Therefore, the adder 69 outputs f (t) shown in Expression (12). The data processing device 52 obtains the blood flow based on the output of f (t) in the same manner as in the first embodiment.

According to the present embodiment, in the manufacture of the laser module 58 for generating a laser beam, an element used generates a specific wavelength, such as a wavelength that is an isosbestic point for oxygenated hemoglobin and reduced hemoglobin. Therefore, the range of component selection is wide.

[0048]

According to the present invention, since the average optical path length is determined by the distance d between the center of the light emitting surface of the light emitting unit and the center of the light receiving surface of the light receiving unit, d is a value corresponding to a desired area. Thus, the tissue blood flow in that region can be obtained. Therefore, it is possible to determine the blood flow of limited tissues such as skin, nerve, and muscle.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration according to a first embodiment of the present invention.

FIG. 2 is a diagram showing light absorption characteristics of oxygenated hemoglobin and reduced hemoglobin.

FIG. 3 is a diagram showing a path of light applied to a living tissue.

FIG. 4 is a diagram showing output data of a blood volume data detection unit.

FIG. 5 is a diagram showing an overall configuration of the first embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of the device shown in FIG. 5;

FIG. 7 is a view for explaining a use state of the device shown in FIG. 5;

FIG. 8 is a diagram showing a modified example of the sensor in the device shown in FIG.

FIG. 9 is a diagram showing an overall configuration of a second embodiment of the present invention.

FIG. 10 is a view showing measurement results when blood volume is measured using a rubber lane gauge.

[Explanation of symbols]

 1, 51 blood volume data measuring device 2, 52 data processing device 3, 53 light detecting means 3a light emitting part 3b light receiving part 4, 54 blood volume data detecting means 4a logarithmic conversion part 4b amplifying part

Claims (8)

[Claims] 1. A light emitting unit having a light emitting surface closely contacted with a living tissue, and a light receiving unit having a light receiving surface closely contacted with the living tissue and converting light received by the light receiving surface into an electric signal. Light detection means, and each value of an average optical path length da in the living tissue from the light emitting surface of the light emitting unit to the light receiving surface of the light receiving unit, hemoglobin concentration a of the biological blood and density b of the biological tissue Blood data detection means for obtaining data relating to the blood volume around the average light path in the living tissue based on the value determined in advance with reference to and the output of the light receiving section of the light detection means. To measure blood volume data. 2. The blood volume data measuring device according to claim 1, wherein the light emitting surface of the light emitting unit and the light receiving surface of the light receiving unit are oriented in the same direction. 3. The light amount detecting means is a means for generating light of one wavelength whose light emitting portion is equally absorbing to both oxygenated hemoglobin and reduced hemoglobin. Is the output value V of the light receiving section and the set value V0
, A logarithmic converter for calculating log (V0 / V), and an amplifier for multiplying the output of the logarithmic converter by α / (da ・ a ・ b) (α; a constant). The blood volume data measuring device according to claim 1 or 2. 4. The light detecting means has a light emitting section for generating light of two wavelengths. The blood volume data detecting means has two light receiving sections corresponding to the two wavelengths A and B. Output value VA, VB and two set values VA0, VB
From 0, a logarithmic converter for calculating log (VA0 / VA) and log (VB0 / VB), and two outputs of the logarithmic converter are βA / (d
aA ・ a ・ b) times, βB / (daB ・ a ・ b) times (βA, βB; constant,
4. An apparatus according to claim 1, further comprising: an amplifier for performing da) for each of the wavelengths A and B; and an adder for obtaining a sum of two outputs of the amplifier. An apparatus for measuring blood volume data according to claim 1. 5. A light emitting unit having a light emitting surface closely contacted with a living tissue, and a light receiving unit having a light receiving surface closely contacted with the living tissue and converting light received by the light receiving surface into an electric signal. Light detection means, and each value of an average optical path length da in the living tissue from the light emitting surface of the light emitting unit to the light receiving surface of the light receiving unit, hemoglobin concentration a of the biological blood and density b of the biological tissue A blood volume data detection unit that obtains data on a blood volume around the average optical path in the living tissue based on a value determined in advance with reference to and a light output unit of the light detection unit; A blood flow meter comprising: a data processing unit that obtains a blood flow rate around a portion where the light emitting surface and the light receiving surface are mounted from a change in data regarding the blood volume detected by the volume data detecting unit. 6. The blood flow meter according to claim 5, wherein the light emitting surface of the light emitting unit and the light receiving surface of the light receiving unit are oriented in the same direction. 7. The light amount detecting means is a means for generating light of one wavelength whose light emitting portion has equal absorption to both oxygenated hemoglobin and reduced hemoglobin. Is the output value V of the light receiving section and the set value V0
, A logarithmic converter for calculating log (V0 / V), and an amplifier for multiplying the output of the logarithmic converter by α / (da ・ a ・ b) (α; a constant). The blood flow meter according to claim 5. 8. The light detecting means has a light emitting unit for generating light of two wavelengths, and the blood volume data detecting means has two light receiving units corresponding to the two wavelengths A and B. Output value VA, VB and two set values VA0, VB
From 0, a logarithmic converter for calculating log (VA0 / VA) and log (VB0 / VB), and two outputs of the logarithmic converter are βA / (d
aA ・ a ・ b) times, βB / (daB ・ a ・ b) times (βA, βB; constant,
8. An optical amplifier according to claim 5, further comprising: an amplifier for performing da) for each light of wavelengths A and B; and an adder for obtaining a sum of two outputs of the amplifier. A blood flow meter as described.