JPS60198128A - Blood pressure measuring apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] ru II Ro / 7) #;irr A @ 1 The present invention directly measures the passage time of blood between two points, and increases blood flow velocity, blood passage time to organs, etc. The present invention relates to a blood flow measuring device that can accurately measure blood flow.

[Technical Preface to the Invention] Generally, when attempting to measure the velocity of blood flow or a value related thereto, an ultrasonic Doppler blood flow meter or the like that utilizes the Doppler effect is used. Ultrasonic Doppler blood flow meter
An ultrasound beam is incident on a blood vessel at an angle other than 90°, and its reflected or transmitted beam is detected to determine the frequency change due to the Doppler effect. It measures the flow velocity of blood flow, and has attracted attention in recent years because it allows the measurement of blood flow velocity in a non-invasive manner. However, in this case, the ultrasonic beam must be correctly incident on the blood vessel to be measured, and the angle of incidence must also be adjusted to ensure accurate measurement.

For this reason, a so-called ultrasonic diagnostic device is usually used in conjunction with the measurement, and measurements are made by setting the emission position and angle of the blood flow velocity measurement beam while looking at ultrasound tomographic images near the area where blood flow is to be measured. I have to.

However, even with this method, it is not easy to correctly direct the measurement beam to the position of blood vessels or small blood vessels that exist deep inside the body, or to correctly set the angle between the curved blood vessel and the measurement beam. Therefore, in this ultrasonic Doppler blood flow meter, measurement errors based on the above-mentioned position and angle errors are large, and highly accurate measurement is almost impossible.

A laser Doppler blood flow meter uses a principle similar to that of the ultrasonic Doppler blood flow meter, but because the principle is similar, it has had almost the same problems as described above.

On the other hand, in addition to these means using the Doppler effect, there is an electromagnetic blood Wt meter using the principle of a so-called electromagnetic flowmeter, which is mainly used in animal experiments and special surgeries. This method detects and measures the flow velocity using electromagnetic induction by attaching a detection unit consisting of a coil, electrode, etc. directly to the blood vessel, but since it is a measurement using electromagnetic induction, S/N is originally low.
The ratio (signal-to-noise ratio) is not very good, and on top of that,
There is also the problem that the state of attachment of the detection unit to the blood vessel greatly affects the measurement sensitivity, and that noise is likely to be generated due to the influence of surrounding air equipment.

Furthermore, in any of these means, the blood flow velocity is determined indirectly by utilizing phenomena such as the Doppler effect or electromagnetic induction caused by the blood flow at the measurement point, and therefore accuracy beyond a certain level cannot be expected.

On the other hand, knowing the organ transit time of blood is extremely effective in diagnosing the functions and disorders of organs, especially the liver, but it is impossible to determine this organ transit time using each of the above-mentioned methods. Ta.

[Objective of the Invention] An object of the present invention is to provide a blood flow measuring device that enables direct blood flow measurement with a simple configuration and can measure blood flow with high precision.

[Summary of the Invention] The present invention includes a pair of light sources and a light detection unit, which are attached to the blood vessel of a subject at a distance from each other, and are connected to the blood vessel directly or via an optical system. first and second detection sections that form a reflected or transmitted optical path to detect a value corresponding to the light absorption of the tissue surrounding the blood vessel, the blood, and a specific dye administered into the blood, and output it as an electrical signal; and a means for receiving the respective outputs of the first and second detection sections and determining the start timing of fluctuation of each detected value by the specific dye, and measuring the time difference between the two determination timings by this means to detect the rain. The present invention is characterized by comprising means for determining the passage time between sections, and an output device for displaying or recording the results of the tightening obtained by this means.

[Embodiments of the invention] FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, 1 and 2 are first and second detectors, respectively, which have basically exactly the same configuration. 1st
The detector 1 uses a narrow band semiconductor light such as a semiconductor laser or a light emitting diode, for example, each having an emission wavelength range corresponding to the absorption wavelength range of the specific dye [1a; For example, a light projection optical system 1C using a photodetector such as a first silicon cell, and a photodetector 1b.
It consists of a light-receiving optical system 1d using an optical fiber etc. that guides light from the blood vessel.
A transmission optical path is formed between the light emitting end of C and the light receiving end of the light receiving optical system 1d with blood IB interposed therebetween.

Specifically, as shown in FIG. 2, the first detector 1 is provided with a deflection prism PP for deflecting the direction of the received light beam by 180 degrees at the light receiving end of the light receiving optical system 1d, and a light source 1a. , the photodetector 1b, the light emitting optical system 1C, and the light receiving optical system 1d are housed in a container 1f having a U-shaped groove-shaped recess 1e formed at the tip side as shown in the figure, and the light emitting optical system 1 is housed in the recess 1e.
The light projecting surface of C and the light receiving surface of the deflection prism PP of the light receiving optical system 1d may be configured to face each other. In this case, the blood vessel 8 can be easily positioned within the transmitted optical path simply by engaging the blood vessel B with the distal end recess 1e of the container 1f.

The second detector 2 includes a light source 2a, a light detector 2a, and the first detector 2a.
The structure is exactly the same as that of the detection unit 1, and when it is attached to a blood vessel, a transmitted light path is formed with a blood vessel B interposed between the light emitting end of the light transmitting optical system 2G and the light receiving end of the light receiving optical system 2d. form.

The outputs of these first and second detectors 1 and 2, that is, the outputs of photodetectors 1b and 2b, are current signals called photocurrents, and are used for first and second I/V conversion (current-voltage conversion), respectively. ) converters 3 and 4 into voltage signals. In addition, in many cases, the photocurrent output of the photodetectors 1b and 2b has a relationship that is not proportional to the absorbance of the portion through which the light passes, such as an exponential relationship. By adding a logarithmic conversion function to the I/V converter 3 and 4, an output proportional to the absorbance is obtained. For example, the above case can be easily realized by using a current/voltage output type logarithmic amplifier as the r/V converter 3.4.

The outputs of the I/V converters 3 and 4, which have a proportional relationship to the absorbance thus obtained, are respectively guided to first and second DC component removal circuits 5.6, and the DC component of the detection signal, i.e. Non-variable components are removed.

These DC component removal circuits 5 and 6 are, for example, sample-and-hold circuits that hold the level at a certain point in time and extract the fluctuation component by taking the difference between this hold level and subsequent input and output levels, or low-cut filters. (reduction removal filter) etc. Further, the outputs of the first and second direct current component removal circuits 5.6 are respectively connected to the first and second DC component removal circuits 5.6 each consisting of a band elimination filter (band elimination filter) using an active filter, for example.
A frequency component corresponding to the pulse wave is removed by the pulse wave removal circuits 7 and 8, and is supplied to first and second A/D converters (analog-to-digital converters) 9 and 10, where it is converted into a digital signal. It is given to the arithmetic processing unit 11.

The arithmetic processing device 11 includes first and second A/D converters 9
．． In response to the output of 10, the fluctuation start point tl and t2 of the output of both cars is detected, that is, the falling point in the case of a change in the negative direction, and the rising point in the case of a change in the positive direction, and the time difference between the two, that is, the elapsed time, is detected. The time Tp is determined, and the blood flow velocity V is calculated from the measurement point interval input and set separately in advance using the operation input unit 12 and the time difference Tp. Then, the arithmetic processing unit 1111 outputs the value of the paralyzed blood flow velocity V and, if necessary, the values used in the calculation process, such as the measurement point interval 1 hour Tp, to the output device 13 consisting of a display or printer for display. Or print it out.

Note that the output device 13 may have a built-in data recorder or the like for recording data, or may be connected to the outside.

In this case, the specific dye mentioned above is indocyanine green (1ndocyanine green), which is used for blood loss rate (hepatic blood flow index) measurement and circulatory function tests for liver examination diagnosis.
anine green (hereinafter abbreviated as rICGJ). This ICG has no side effects on living organisms, and is a dye that can be easily measured for absorbance in blood, making it ideal for this measurement. When ICG is used, the maximum absorption wavelength in a protein-containing solution such as blood is 805 nm, and the maximum absorption wavelength in a solution containing proteins such as blood is 805 nm.
．． A semiconductor laser with an emission wavelength of 800 nm or 8
A light emitting diode that emits light in a narrow wavelength range near oom is optimal. Of course, at this time, the photodetectors 1b and 2b have sufficient sensitivity to the same wavelength range, and the optical system IC,
Id, 2c, and 2d are also configured to reduce attenuation in the same wavelength range.

Next, specific operations and effects of blood flow measurement using such a configuration will be explained.

Here, we are considering an example in which blood flow is measured in an animal experiment or in a human body during surgery.

First, the first and second detectors 1.2 are respectively attached to two locations on the portion of the blood vessel B of the subject to be measured.

At this time, as shown in FIG. 1, the first detector 1 is placed on the upstream side, and the second detector 2 is placed on the downstream side. Then, the distance between both detectors 1-2 is measured, and the distance between the measurement points 11iD is entered into the arithmetic processing unit 11 from the operation input section 12 and set, and measurement is started. In this state, ICG, which is the above-mentioned specific dye, is administered to one subject by, for example, intravenous injection.

After this static movement, the first IC at the position of both detectors 1 and 2
The arrival timing of G is detected, and the blood flow velocity is measured based on the time difference between these two points and the distance between the two points.

The arithmetic processing unit 11, which is the central part of this processing, can be realized by software processing using a configuration such as a microcomputer, and the details of the processing in this arithmetic processing unit 11 will be explained with reference to the flowchart shown in FIG. .

First, the outputs of the first and second A/D converters 9 and 10 based on the outputs of the first and second detectors 1.2 are respectively captured at predetermined time intervals and stored separately in memory. (Pl). A series of data stored in the memory on the first detector 1 side is read out and the amount of variation over time, that is, the magnitude of the slope in the signal waveform is differentiated (specifically, for example, the series of data is The difference between each adjacent piece of data or every set of data at intervals of a certain number of pieces of data may be sequentially calculated, etc.), and this is compared with a preset reference value to detect the starting point t1 of fluctuation in the input signal. (P2). Similarly, a series of input data stored in the memory on the second detector 2 side is read out, the amount of variation over time is determined by differential processing, etc., and compared with the above reference value, the variation in the input signal is determined. Detect starting point t2〈
P3). These two fluctuation starting points t1. From t2, for example, the elapsed time MTp between the two is calculated by setting Tp = t2 - tl (P4).

The blood flow velocity v=D/Tp is calculated based on this elapsed time Tp and the measurement point interval input and set separately in advance (P5). The blood flow velocity V obtained above and, if necessary, the measurement point interval D and the elapsed time Tp are outputted from the output device 13 (P6).

In this way, the blood flow velocity V of the subject can be easily and extremely accurately measured.

Further, when measuring the organ transit time of blood, the measurement is performed by attaching the first and second detectors 1 and 2 to a blood vessel flowing into the target organ and a blood vessel flowing out from the target organ, respectively. In such a case, the measurement point interval is generally unknown and there is no need to calculate the blood flow velocity V, so the measurement point interval is not input. Then, the elapsed time T+1 between measurement points may be output by the same measurement process as described above.

In this way, the passage 118 of blood through the organ can also be easily measured.

In this case, by using semiconductor elements as described above for the light sources 1a, 2a and photodetectors 1b, 2b of the detector 1.2, and using optical fibers for the optical systems 1c, ld, 2c, 2d, the detector 1.2 can be made smaller, lighter, and more accurate, and as a result, it can be easily attached to blood vessels and the burden on living organisms can be relatively reduced, making it easier to perform measurements not only in animal experiments but also in surgeries.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings (and can be implemented with various modifications without changing the gist thereof.

For example, in the embodiment described above, the arithmetic processing unit 11
1.7-Paris n type 5
It can also be easily realized by using a bird sieve hII ware.

That is, the inputs from the A/D converters 9 and 10 are respectively given to a differentiator to take the differentiation, and the differentiated signals are each compared with a reference value by a comparator to detect the fluctuation start point. When the timing device is started by the fluctuation start point detection signal from the second detector 1 side, and the time measurement by the clock device is stopped by the fluctuation start point detection signal from the second detector 2 side, and the time taken for blood to pass through the organ is determined. If you want to measure the blood flow velocity, give the time measurement result to the output device 13 as it is, and if you want to measure the blood flow velocity, give the above time measurement result to a divider, divide it by the measurement point interval that is input and set separately, and then give it to the output device 13. good. If this is done by analog processing, the A/D converters 9 and 10 are of course unnecessary.

Further, the DC component removal circuits 5, 6, pulse wave removal circuits 7, 8, etc. shown in the same embodiment are provided to easily and reliably detect the fluctuation starting point. When using a dye that exhibits a significant change in absorbance, such as (because the detection signal of detectors 1 and 2 varies greatly due to administration to the subject), there are often practical problems even if the above parts are omitted as appropriate. It can be implemented. Furthermore, when using a dye with a large change in absorbance, the linearity of the detection signal with respect to absorbance is not very important, so 1. /V converter 3
．． Logarithmic correction, etc. at 4th magnification becomes unnecessary.

Of course, if a semiconductor laser or a light emitting diode with a narrow emission band is not used as the light sources 1a and 2a in the detectors 1 and 2, a passband with a narrow band is used between the light source and the blood vessel or between the blood vessel and the photodetector. Just insert a narrow filter. Of course, in the embodiment shown in FIG. 1, a filter similar to that described above may be provided between the blood vessel B and the photodetector 1b.

Furthermore, as shown in FIG. 4, a detector in which the detection optical path is formed by a reflected optical path may be used.

That is, the detectors 21 and 22 shown in FIG.
light 111a, 2a of detector 1.2 and photodetector 1b,
Light source 218.22a and photodetector 21b similar to 2b
, 22b and a light projection optical system 21 using an optical fiber or the like.
c, 22c, light receiving optical system 2 similarly using optical fiber etc.
1d and 22d, and allows the inflow of a specific dye to be detected by detecting light absorption characteristics due to reflection in the blood vessel B.

In this case, since detection is performed on the reflected optical path, the detector 21.
22 does not necessarily have to be in direct contact with the blood vessel B, but can be measured by contacting from the body surface with the tube passing portion of a region where the blood vessel B is located near the body surface, such as near the wrist or near the joint between the elbows. is possible. Therefore, this method can be easily used not only during surgery and animal experiments, but also for regular clinical tests.

In addition, in any of the above-mentioned embodiments, the light emitting and light receiving optical systems may be provided as necessary, and the light source and photodetector may be of a large size or whose characteristics are easily affected by body temperature, etc. In some cases, it is desirable to provide this to reduce the effects of heat or to downsize the entire detector, but if a sufficiently small light source and photodetector are used, or where the detector should be installed for measurement. If the detector is not narrow (if the overall size of the detector can be increased to some extent), it is often unnecessary to provide a light emitting and receiving optical system. Of course, the light projecting and light receiving optical system may be configured using not only optical fibers, prisms, etc., but also condensing lenses and reflecting mirrors.

Furthermore, if it is necessary to measure the distance between measurement points, one detector may be fixed to one end of a flexible scale such as a so-called flexible chamber 3!1, etc., in order to facilitate measurement. , the other detector may be movably attached to this scale, or a flexible tape measure-shaped measuring instrument may be attached to one detector and the tip of the measuring section (pull-out end) of this measuring instrument may be attached.
Alternatively, the other detector may be attached to the other detector.

Note that in cases where the pulsating flow valve is large, such as in an artery, the blood flow velocity at a specific location changes from time to time, so a simple measurement between two points may not provide sufficient accuracy. This tendency is remarkable when the distances between two measurement points are similar. To deal with such a case, simply make the distance between the measurement points sufficiently long to reduce the influence of the error. In addition, if the distance between the measurement points cannot be long enough, or if you want to obtain even higher accuracy, a large number (at least several) of detection units are arranged at minute intervals near the start and end points of the measurement section. Then, the speed distribution in each short section is determined by multi-point measurement, and the speed state (
What is necessary is to obtain the velocities between the points having the same phase). For this second method, it is desirable to specially manufacture and prepare a detector equipped with a plurality of sets of detection sections for multi-point measurement. [Also, it goes without saying that if there is no need to display output or print data and it is sufficient to simply record, it is sufficient to use only a data recorder as the output device.

Once the blood flow velocity is known, the blood flow volume can be easily calculated from that and the vessel diameter. This calculation may be processed by the arithmetic processing unit 11 or the like.

[Effects of the Invention] According to the present invention, it is possible to provide a blood flow measuring device that enables direct blood flow measurement with a simple configuration and can measure blood flow with high precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a specific configuration of a detector in the same embodiment, and FIG. 3 is a block diagram showing the configuration of a detector in the same embodiment. FIG. 4 is a flowchart for explaining an example of a specific process of the thread processing apparatus, and is a diagram that does not schematically show the configuration of the main part in another embodiment of the present invention. 1.2.21.22...Detector, 3.4...I/''
V (current-voltage) converter, 5.6... DC component removal circuit, 7.8... Pulse wave removal circuit, 9, 10... A, /D
<ana [] good digital) converter, 11... arithmetic processing unit, 12... operation input section, 13... output device H0
Applicant's agent Patent attorney Takehiko Suzue 3rd Fj! JI 4th drawing

Claims (1)

[Claims] each having a pair of light sources and a light detection unit, each of which is attached to a blood vessel of a subject at a distance from each other to form a reflected or transmitted optical path through the blood vessel directly or via an optical system; first and second detection sections that detect a value corresponding to the absorption of the tissue surrounding the blood vessel, blood, and a specific dye administered into the blood and output it as an electrical signal, and the first and second detection sections means for receiving each output and determining the start timing of fluctuation of each detection value by the specific dye, and means for measuring the time difference between the two determination timings by this means to calculate the transit time between the rain detection parts; A blood flow measuring device characterized by comprising an output device for displaying or recording calculation results obtained by this means.