JP3091269B2 - Surface blood flow measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blood flow measuring apparatus capable of quantitatively and noninvasively measuring the surface blood flow dynamics of a certain area of a living skin or organ.

[0002]

2. Description of the Related Art Methods for measuring the blood flow velocity and blood flow of a living body have long been developed, for example, a method of measuring an average blood flow using a measuring cylinder and a method of dye dilution. Recently, a radioisotope dilution method, an electromagnetic blood flow meter, an ultrasonic Doppler method, a thermocouple, a thermal gradient blood flow meter, a laser Doppler method, and the like have been developed.

[0003] The graduated cylinder method is a method of measuring the amount of blood flowing out by cutting a blood vessel. In this method, for example, in the case of skin, an incision is made at a certain depth using a scalpel or the like, and the amount of bleeding is measured. However, this method was not common because it would cause significant pain to the subject. The dye dilution method is a method of injecting a dye into a tissue to measure the disappearance rate, but the measurement is not always performed accurately due to the influence of adsorption of a dye to a living body or the like. This method was also not generally used because it caused a great deal of pain to the subject.

[0004] The recently developed radioisotope dilution method is similar to the dye dilution method, but is one of the methods with extremely high sensitivity. However, continuous measurement within the tracer's disappearance time is not possible. In addition, actual measurements are not often used in clinical practice except for special cases such as research purposes. The electromagnetic blood flow meter has dramatically improved the quantification of the flow rate using a square-wave-driven magnetic field, and is now often used clinically. However, it is necessary to surgically exfoliate the blood vessels of the limb for measurement and to attach a probe of a blood flow meter, and non-invasive measurement is impossible.

[0005] The above-mentioned blood flow measuring devices have different measuring principles and are superior in function, but the biggest problem is that the invasion to the living body is forced. To solve these problems, an ultrasonic Doppler method, a thermocouple, a thermal gradient blood flow meter, a laser Doppler method, and the like have been developed. The ultrasonic Doppler method has been widely used due to the development of the pulse Doppler method. Although the accuracy and resolution are inferior to those of the laser Doppler method described later, they are widely used in clinical practice because they are noninvasive and simple.

A thermocouple and a thermal gradient blood flow meter are systems for sensing the surface moving speed of heat, and have a problem that the response is rather poor and detailed data cannot be obtained, but they respond satisfactorily to changes over time. I do. The laser Doppler blood flow meter is applied only to the fundus blood flow and skin blood flow because it is limited to the area where the laser beam reaches, but it has excellent temporal and spatial resolution, no electrical obstruction, and a very excellent system It is.

[0007]

However, the measuring devices such as the ultrasonic Doppler method, the thermocouple, the thermal gradient blood flow meter, and the laser Doppler method described above have a sensor portion composed of only one element. Therefore, as long as each sensor part is fixedly attached to the same part, it responds well to changes in the time axis, but it cannot perform zero correction for changes in the blood flow velocity axis, so the quantitativeness is poor and absolute evaluation There was a problem that was not possible. Therefore, it was impossible to obtain data on changes in blood flow due to site differences between patients or within the same subject.

[0008] Some laser Doppler blood flow meters have a plurality of sensor portions, which are used only for the purpose of improving the accuracy of the measurement site, and the above-mentioned problems still exist. I do. In addition, the conventional blood flow measurement devices, the measurement site may be close to a point, often gives a large change in the output by the strength of the installation pressure at the sensor tip,
This was also one of the major reasons for lack of quantitativeness.

Accordingly, it is an object of the present invention to provide a surface blood flow measuring device capable of non-invasively measuring surface blood flow quantitatively and accurately.

[0010]

According to the present invention, there is provided a filer for incident laser light for detecting a surface blood flow of a subject and generating an output signal.
A plurality of sensor elements each comprising an optical fiber and a fiber for reflected laser light, a sensor unit in contact with the subject, a signal conversion unit for converting an output signal from the sensor element into a predetermined measurement signal, and measuring the measurement signal. The above object has been achieved by providing a surface blood flow measuring device, comprising: a display unit for displaying a value as a value.

In the surface blood flow measuring device according to the present invention, the contact surface of the sensor section with the subject may be 0.1 cm ² or more and 500 cm or more.
It is preferable that the have a contact area of ² or less.

[0012]

According to the first aspect of the present invention, an output signal is generated from each sensor element in accordance with the surface blood flow of the subject by allocating the sensor section to the subject, and the output signal converting section generates the output signal. It is converted into a predetermined measurement signal. At this time, since the sensor unit is provided with a plurality of sensor elements, a single measurement site can simultaneously or selectively measure a plurality of locations,
By averaging the fluctuation of each measured value, calibration becomes possible and quantitative and accurate measurement can be performed. In addition, even if the displacement of the sensor installation site occurs, accurate data of the area can be obtained by averaging the outputs of the plurality of sensor elements.

According to the invention described in claim 5, the sensor section
The contact surface of the subject at 0.1 cm ^TwoMore than 500cm^TwoLess than
Since the pressure is set lower, the installation pressure of the sensor
The effect on the position can be reduced. The sensor
0.1cm contact area^TwoMore than 500cm^TwoLimited to
The reason is that the area of the sensor part is 0.1cm^TwoLess than
It is not possible to obtain a sufficient effect to reduce the pressure,
500cm^TwoIf it exceeds, it is too large and simple as a device
Because it cannot function.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention. The surface blood flow measuring device 2 according to the first embodiment of the present invention uses the principle of laser Doppler, and uses an optical fiber 4 as a sensor element. The optical fiber 4 is composed of a fiber for incident laser light and a reflected laser. One end 4a is made of an optical fiber,
The other end 4b is a multi-channel 8 as a control device.
Is connected to the signal conversion unit 10 via the.

The sensor section 6 includes a plurality of optical fibers 4,
For example, one end 4a as a sensor element of five, ten, twenty, etc. optical fibers 4 is held at appropriate intervals. The installation surface of the sensor unit 6 on the subject is formed in a circular or elliptical shape, and the area thereof is set to be 0.1 cm ² or more and 500 cm ² or less, so that the installation pressure generated at the measurement site is reduced. still,
In this embodiment, the installation area of the sensor section 6 is practically formed to a size of 1.5 cm ² or more and 10 cm ² or less.

In each sensor element 4a of the sensor section, the interval between the incident light and the reflected light of the laser is preferably 0.01 to 10 mm, and the depth of the measurement site can be adjusted by finely adjusting the interval. Usually, for the purpose of measuring skin blood flow, 0.05 to 5 mm is particularly preferable. Further, the other end 4b of the plurality of optical fibers 4 is connected to the multi-channel 8, and simultaneously or sequentially selectively.
An output signal from each optical fiber 4 is taken out.

The signal converter 10 includes a laser transmitting mechanism 12 for outputting a laser beam to the optical fiber 4 connected to the multi-channel 8, and a converting mechanism 14 for changing the output from the optical fiber 4 to a predetermined measurement signal. . The laser transmitting mechanism 12 includes a pair of translucent mirrors 18a and 18b that transmit a part of the laser light output from the laser 16 and reflect the other part, and the translucent mirrors 18a and 18b.
A pair of reflecting mirrors 20a and 20b which form a rectangle with the pair b are provided, and an ultrasonic shifter 22 is disposed between the pair of reflecting mirrors 20a and 20b. With such a configuration, a part of the laser light transmitted from the laser 16 is transmitted to the multi-channel 8 through the pair of translucent mirrors 18a and 18b. On the other hand, the other part of the laser light reflected by the translucent mirror 18a is reflected by the reflecting mirrors 20a and 20b via the ultrasonic shifter 22, and then reflected by the translucent mirror 18b.
And is sent to the conversion mechanism 14. The reflecting mirror 20b
A photodetector 24a is located between the mirror 18b and the translucent mirror 18b.

The conversion mechanism 14 is adapted to be introduced into a spectrum analyzer 28 via a photodetector 24b and a differential amplifier 26 arranged on an optical path for receiving the laser beam transmitted through the translucent mirror 18b. That is,
The change in spectrum caused by the optical path difference between a part of the laser light directly introduced and the light returned as an output signal from the optical fiber 4 is measured.

The spectrum analyzer 28 is further connected to a recorder 30 as a display for displaying a measurement signal as a measurement value, and records the measurement result on a recording paper or the like. According to the surface blood flow measuring device 2 according to the first embodiment, a part of the laser light emitted from the laser 16 is sent to the multi-channel 8, where it is sequentially or selectively supplied to the predetermined optical fiber 4. I do.

Then, an output signal output using a laser as a medium is reflected by a semi-transparent mirror 18b through a multi-channel 8 in accordance with the blood flow velocity at the measurement site where the sensor section 6 is in contact. After being introduced into the conversion mechanism 14 and subjected to arithmetic processing by the spectrum analyzer 28, it is converted into a measurement signal and recorded on a recording paper or the like by the recorder 30. Then, by selecting the optical fiber 4 as each sensor element 4a in the multi-channel 8 as needed, it is possible to obtain measured values at different positions.

Specifically, the calculation processing of the reflected light laser is performed through a photodetector ultrasonic shifter, a differential amplifier, a spectrum analyzer, and the like. According to this embodiment, since the blood flow velocity at a plurality of points can be measured, quantitative measurement can be reliably performed. Further, by providing a plurality of measurement points, the measurement site can be expanded from the point to the surface, and the measurement error due to the displacement of the mounting site can be reduced.

It is also possible to analyze the output from each sensor element independently, and simply to average each output to indicate the blood flow. It is also possible to select a response sensor and output it locally. Further, the output from each sensor element can be analyzed for flow turbulence on a measurement surface together with blood flow velocity profile measurement by multi-channeling, and data can be processed into an image. [Second embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 9. Detailed description of the parts will be omitted.

FIG. 6 is a schematic structural diagram of a second embodiment of the present invention.
FIG. 9 is a plan view of a sensor unit used in the second embodiment. The surface blood flow measurement device 32 according to the second embodiment includes one laser light source 34 and seven introduction optical fibers 36a connected to the laser light source 16 and into which laser light is introduced.
A sensor section 6 that holds the sensor element 4a, which is the tip of the introduction optical fiber 36a, and abuts on the subject; and seven derivation optical fibers 36b that derive output signals from the sensor elements 4a. Each outgoing optical fiber 3
6b, a signal conversion mechanism 14 for collectively inputting the output signals derived and inputting the output signals to the photodetector 38, performing optical averaging and converting the signals into a measurement signal.

As shown in FIG.
The sensor elements 4a are arranged at substantially equal intervals, the distance L between the sensor elements 4a is set to about 5 mm in this embodiment, and the diameter R of the sensor section 6 is set to about 16 mm. Then, the laser light of about 15 mW emitted from the laser light source 34 is simultaneously distributed to the seven introduction optical fibers 36a, and each of the sensor elements 4a arranged at equal intervals in the sensor unit 6.
To irradiate the subject (output of about 1.5 mW). The reflected light from the subject passes through the optical fiber 36b for leading out the sensor element 4a, and the light receiver 38 and the analysis circuit 28
Is introduced into the signal conversion mechanism 14 comprising. In the signal conversion mechanism 14, one light receiver 38 and one analysis circuit 28 are provided. In the analysis circuit 28, the Doppler signal obtained by adding the seven reflected laser lights is output as the “added average blood flow signal”. You.

According to the second embodiment, the outputs from the respective sensor elements are added and averaged by the photodetector. Therefore, in addition to the above-described first embodiment, a value with little measurement error and high reproducibility is obtained. Obtainable. In addition, in the case of the present embodiment in which one light source is shared, it is possible to make the optical fiber extremely thin or to be distributed due to the nature of the optical fiber, and it is easy to increase the number of sensor elements 4a in the sensor unit 6. . Third Embodiment Referring to FIGS. 7 and 9, a third embodiment of the present invention will be described.
Although the embodiment will be described, the same portions as those in the first embodiment are denoted by the same reference numerals, and detailed description of those portions will be omitted.

FIG. 7 is a schematic structural diagram of a third embodiment of the present invention.
FIG. 9 is a plan view of a sensor unit used in the third embodiment. In the surface blood flow device 42 according to the third embodiment, similarly to the above-described second embodiment, laser light introduced from one laser light source 34 is distributed to seven introduction optical fibers 34a. Each of the lead-out optical fibers 34b connected to each sensor element 4a of the sensor section 6 is independently connected to a light receiver 38 and an analysis circuit 28, and each analysis circuit 28
Are connected to an averaging circuit 44.

That is, the output signal derived from each sensor element 4a is analyzed by its own light receiving element 38 and analysis circuit 28, respectively, and the measurement signal output from each analysis circuit 28 is added by the averaging circuit 44. It averages and outputs as an averaged blood flow signal. [Fourth Embodiment] Referring to FIGS. 8 and 9, a fourth embodiment of the present invention will be described.
Although the embodiment will be described, the same portions as those in the first embodiment are denoted by the same reference numerals, and detailed description of those portions will be omitted.

FIG. 8 is a schematic structural diagram of a fourth embodiment of the present invention.
FIG. 9 is a plan view of a sensor unit used in the fourth embodiment. In the surface blood flow device 52 according to the fourth embodiment, seven laser light sources 16 are provided, the introduction optical fiber 4a is connected to each laser light source 34, and the laser light is independently incident on the sensor unit 6, and the output from each sensor element 4a is output. Are connected to seven outgoing optical fibers 4b, respectively, and each outgoing optical fiber 4b is connected to one light receiver 38.

That is, in the fourth embodiment, while there are a plurality of incident laser light sources, one light receiver 38 and one analysis circuit 28 are provided, and the analysis circuit 28 outputs seven reflected laser light beams. The optically added Doppler signal is output as an “averaged blood flow signal”. [Measurement Examples 1 and 2] Hereinafter, measurement examples 1 and 2 according to the first embodiment will be described with reference to FIGS.

FIGS. 2 to 5 are graphs showing measurement results based on the first embodiment. (Measurement conditions) Laser Doppler main unit (PeriMed Periflux PF3 remodeled product) Sensor area 2 square centimeters Number of sensor elements 10 Approximately equal arrangement Measurement time 30 seconds Measurement site Measurement example 1: Human cheek center Measurement example 2: Human forearm Bending side Measurement temperature Measurement example 1: 25 degree / 60% Humidity measurement example 2: 35 degree / 60%, 20 degree / 60% (Measurement result) The measurement result under the condition of measurement example 1 is second.
This is shown in the figure and FIG. FIG. 2 shows the measurement results on the first day and FIG. 3 shows the measurement results on the same part of the human cheek on the second day.

FIGS. 4 and 5 show the measurement results under the conditions of Measurement Example 2. FIG. FIG. 4 shows the measurement results under the condition of 35 degrees / 60%, and FIG. 5 shows the measurement results at substantially the same site on the human arm. . 2 to 5, the line segments indicated by reference numerals 1 to 10 indicate the average output ± standard deviation (30 seconds) from each sensor element, and the line segments indicated by reference sign N indicate the total number of sensor elements. The output mean ± standard deviation (30 seconds) is shown.

As is clear from the results of Measurement Example 1, 1
Although the values of the sensor elements 4a provided at the zero point greatly differ from each other, stable data could be obtained by averaging ten data. On the second day, the same site was measured again under the same conditions. As a result, stable data could be obtained by averaging 10 data.

As is clear from the results of Measurement Example 2, even when the measurement condition is lowered from 35 degrees to 20 degrees, the data from the individual sensor elements are averaged to obtain stable data on the blood flow. I was able to. [Measurement Example 3] A measurement example 3 according to the third embodiment will be described below with reference to FIGS. 10 to 11 of the accompanying drawings.

FIGS. 10 and 11 are graphs showing measurement results based on the third embodiment of the present invention. Sensor part 6
The sensor element 4a to which the optical fiber 36a for introduction and the optical fiber 36b for derivation are connected is placed at one place in the center and arranged at 6 points around the periphery at 5mm intervals, so that a total of 7 sensor elements 4a are arranged. I have.

The measurement was performed at approximately the center of the forehead of a human and at five points 5 mm above, 5 mm left, 5 mm right and 5 mm below the center. The measurement was performed by moving the sensor unit 6. The results are shown in FIG. 10 and FIG. 10 and 11
Each of the measurement graphs shown in Fig. 7 shows the output value of each sensor element 4a. That is, the vertical columns indicate the respective sensor elements 4a, and the horizontal columns indicate the measurement sites. Therefore, each graph shows the relationship between the output of each sensor element 4a at each measurement site and the time, with the vertical axis representing the output and the horizontal axis representing time.

The lowermost row of each of FIGS. 10 and 11 is a graph showing the calculated average of the values obtained by the seven sensor elements 4a. The measurement time at each site is 4 minutes.
As is clear from the graph, the blood flow waveforms output from the individual sensor elements 4a are different from each other. Typical examples are, for example, center, 5 mm above, 5 mm
Blood flow waveforms such as right, 5 mm down, etc. These individual data show the blood flow waveform itself from the conventional single sensor element without any correction, and understand how the reproducibility of the data could not be obtained by shifting the measurement points with the conventional measurement equipment it can.

On the other hand, by electrically adding and averaging these individual data, a stable output could be obtained as shown at the bottom. That is, approximately the center of the forehead of the measurement site and 5 mm above, 5 mm left, 5 mm right, 5 mm
It was found that the average value of the lower skin blood flow hardly changed. Note that the same measurement as in the above-described measurement example 3 was performed on the second and fourth examples, and a result similar to the graph of the averaging of the above-described measurement example 3 was obtained.

The present invention is not limited to the above-described embodiments and measurement examples, but can be variously modified without departing from the gist of the present invention. For example, the reflected light derived from each derived optical fiber is not limited to scanning at the same time, and may be scanned sequentially. After averaging and calibrating the output from each sensor element, it is also possible to perform a baseline correction of the output from the arbitrarily selected sensor element to pursue a highly quantitative blood flow change over time. .

It is also possible to record the output from each sensor element over time, perform a frequency analysis of the waveform by Fourier transform or the like, and obtain a power spectrum.
This has made it possible to sense partial disturbances in surface blood flow, and to quantify changes in blood flow. Furthermore, in the above-described embodiment, an example in which laser Doppler is used as a measurement principle has been described. However, the present invention is not limited to this , and the present invention is not limited to this embodiment.
Incidentally, according to the laser Doppler method, it is possible to simplify the structure when increasing the number of sensor elements for using an optical fiber, preferred.

[0040]

According to the first aspect of the present invention, a fiber for incident laser light and a fiber for reflected laser light are provided in the sensor portion .
Since a plurality of sensor elements made of fibers are provided, the surface blood flow can be quantitatively and accurately measured. According to the invention as set forth in claim 5, since the contact area with the subject in the sensor section is set to 0.1 cm ² or more and 500 cm ² or less, the installation pressure of the sensor section is relaxed, and the measurement error caused by the installation pressure is reduced. Thus, the surface blood flow can be quantitatively and accurately performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention.

FIG. 2 is a graph showing measurement results based on a first example of the present invention.

FIG. 3 is a graph showing measurement results based on the first example of the present invention.

FIG. 4 is a graph showing measurement results based on the first example of the present invention.

FIG. 5 is a graph showing measurement results based on the first example of the present invention.

FIG. 6 is a schematic configuration diagram of a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a third embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a fourth embodiment of the present invention.

FIG. 9 is a plan view of a sensor unit used in the second to fourth embodiments.

FIG. 10 is a graph showing measurement results based on a third example of the present invention.

FIG. 11 is a graph showing measurement results based on a third example of the present invention.

[Explanation of symbols]

 2, 32, 42, 52 Surface blood flow measuring device of the present invention 4 Optical fiber (sensor element) 6 Sensor unit 8 Control device 10 Signal conversion unit 30 Recorder (display unit)

Continuation of front page (56) References JP-A-57-25835 (JP, A) JP-A-63-21035 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 5 / 00-5/03

Claims (5)

(57) [Claims] 1. A fiber for incident laser light for detecting a surface blood flow of a subject and generating an output signal, and a fiber for reflected laser light.
A sensor unit provided with a plurality of sensor elements made of fibers, which comes into contact with the subject; a signal conversion unit that converts an output signal from the sensor element into a predetermined measurement signal; and a display unit that displays the measurement signal as a measurement value And a surface blood flow measuring device. 2. A control device, wherein the plurality of sensor elements are connected between the sensor section and the signal conversion section, and the control apparatus selectively controls extraction of an input signal and an output signal to each sensor element. The surface blood flow measuring device according to claim 1, further comprising: 3. The surface blood flow measuring apparatus according to claim 1, wherein the apparatus is a laser Doppler blood flow measuring mode. 4. The surface blood flow measurement device according to claim 1, wherein the signal conversion unit includes an analysis device that performs arithmetic processing on the measurement signal and performs image analysis. 5. A front Symbol sensor unit has a contact surface with the subject 0.
Surface blood flow measuring apparatus according to claim 1, characterized in that it has a contact area of 1 cm ² or more 500 cm ² or less.