JP4641809B2 - Biological information measuring device - Google Patents

Description

  The present invention relates to a technique for measuring the viscosity state of blood flowing in an arterial blood vessel, particularly for evaluation of blood rheology indicating blood fluidity in a living body.

  As one of the examination items for judging the health condition of the human body, blood rheology measurement focusing on blood fluidity has attracted attention. As a means for measuring blood rheology, a microchannel flow analyzer has been developed that measures the time for a certain amount of blood collected from a subject to pass through a microchannel (microchannel) (see Non-Patent Document 1). . At present, the micro-channel flow analyzer is a standard machine in blood rheology measurement.

  However, it is necessary to collect blood as described above in the measurement using a microchannel flow analyzer, and the measurement can be performed only by medical institutions, and it is great for the purpose of easily checking the health condition at any time. There is an inconvenience. In addition, blood sampling has a large physical and psychological burden on the subject, and the number of times that the measurement work can be performed per day is only a few times at most, so there is a problem that continuous data cannot be obtained in time series. is there.

As one of the indicators of blood rheology, blood viscosity and in-vivo blood flow velocity are considered to have a strong correlation. That is, it is considered that when the blood fluidity is low (viscosity is high), the blood flow velocity is slow, and when the fluidity is high (viscosity is low), the blood flow velocity is high. Therefore, it is possible to indirectly know the blood viscosity by measuring the blood flow velocity in the living body. Therefore, conventionally, in order to measure a blood flow velocity strongly correlated with blood viscosity, the invention is a non-invasive invention that measures blood flow velocity from the Doppler shift of an ultrasonic wave that propagates in a living body and reflects to the blood flow in the blood vessel. A Doppler system biological information measuring device has been proposed (see Patent Document 1 or 2). In this technique, the blood flow velocity Vh measured by the Doppler method is corrected by the maximum blood pressure value Ph of the living body (human body), and the corrected blood flow velocity Vc is expressed as Vc = Vh / Ph (expression) as one index indicating blood rheology. 1)
When Vc is large, the blood fluidity is high (viscosity is low). Conversely, when Vc is small, the fluidity is low (viscosity is high).
Japanese Patent Laid-Open No. 2003-159250 “Biometric Information Measuring Device” Japanese Patent Laid-Open No. 2003-290226 “Circulation Dynamics Measurement Device, Circulation Dynamics Measurement Method, Blood Pressure Measurement Method, and Circulation Dynamics Sensor” Keiji Kikuchi “Measurement of whole blood fluidity using a capillary model” (Food Research Result Information, NO.11, 1999)

  In non-invasive Doppler blood rheology measurement that measures blood flow velocity from Doppler shift of ultrasonic wave that propagates in living body and reflects from blood flow in blood vessel, measurement data by micro-channel flow analyzer for specific subjects Data with high correlation was obtained. However, when measurement is performed on a plurality of subjects, the correlation may be reduced in comparison of data between different subjects in the conventional technique due to individual differences (individual differences) in the arterial blood vessel diameter of the living body. As a conventional technique corresponding to this problem, an apparatus for measuring a blood vessel diameter with a pulsed ultrasonic echo has been proposed (Patent Document 2). However, since the technique described in Patent Document 2 is a method for measuring a time difference between reflected pulses, it is extremely difficult to separate reflected signals when there are a plurality of blood vessels. Since it is difficult to distinguish between blood vessels, it could not be applied except for measurement of a simple tissue structure site in which only one arterial blood vessel exists in the vicinity. For example, since there are a plurality of blood vessels at the fingertip, accurate blood viscosity measurement has been impossible.

  Therefore, the invention of the present application not only collects blood but allows anyone other than an expert to easily measure an accurate blood flow velocity and enable blood rheology to be measured at low cost as well as a complicated blood vessel structure such as a fingertip. It is an object of the present invention to provide a biological information measuring device that can perform measurement at various sites and can perform measurement with excellent correlation even in data between different subjects.

  In order to solve the above problem, in the present invention, measurement is performed using a blood flow velocity sensor in which a plurality of ultrasonic sensors each including an ultrasonic transmission element and an ultrasonic reception element are combined, and a blood vessel imaging apparatus. . In general, the velocity of the viscous fluid flowing in the pipe is proportional to the pressure and the square of the pipe diameter, and inversely proportional to the viscosity. Therefore, from the above relationship, the velocity of blood flowing in the living body (in the blood vessel) is measured with an ultrasonic sensor, and the pressure is measured with a sphygmomanometer. The arterial blood vessel diameter is detected from a blood vessel image photographed by the image photographing device. Therefore, fluidity can be obtained from the above parameters.

  By using a combination of an ultrasonic sensor and an optical sensor, anyone can easily measure blood rheology without collecting blood from a subject, and by obtaining data on arterial blood vessel diameter from images, The accuracy of the device is improved.

(Embodiment 1)
First, the structure of an Example is demonstrated based on drawing. FIG. 1 is a block diagram showing the configuration of the measuring apparatus of the present invention. FIG. 2 shows a blood flow velocity sensor used in the present invention. FIG. 3 is a schematic diagram showing an outline of the principle of ultrasonic Doppler signal measurement.

The blood flow velocity sensor is a combination of two pairs of ultrasonic sensors, that is, an ultrasonic sensor 1a including a transmitting element 2a and a receiving element 3a, and an ultrasonic sensor 1b including a transmitting element 2b and a receiving element 3b. . The transmitting elements 2a and 2b and the receiving elements 3a and 3b of the ultrasonic sensors 1a and 1b are all piezoelectric vibrating elements in which an electrode thin film is formed on a piezoelectric ceramic plate. In the present embodiment, the ultrasonic frequency is 15 MHz. In the present invention, two pairs of ultrasonic sensors 1a and 1b are used and arranged on the sensor support substrate 10 so that the directions of directivity of ultrasonic emission and reception are not parallel to each other. As shown in FIG. 3, the blood flow velocity is measured by bringing a living body 71 (such as a fingertip of a subject) into contact with the blood flow sensor.
The ultrasonic wave (transmission wave 13a) emitted from the transmitting element 2a of the ultrasonic sensor 1a propagates through the living tissue and is reflected by the blood flowing through the blood vessel. The reflected wave 14a changes to a signal subjected to Doppler shift according to the blood flow speed. This reflected wave is received by the receiving element 3a. Similarly, with respect to the ultrasonic sensor 1b, the ultrasonic wave (transmitted wave 13b) emitted from the transmitting element 2b is reflected by the Doppler shift due to blood flow and is detected by the receiving element 3b, but the ultrasonic sensors 1a and 1b Then, the directivity directions in which ultrasonic waves are emitted are different. The blood flow velocity can be calculated from the angle difference α between the ultrasonic sensors 1a and 1b and the respective Doppler shift frequencies ΔFa and ΔFb obtained from the signals of the ultrasonic sensors 1a and 1b.

  The ultrasonic measurement unit 50 includes a blood flow velocity sensor including two pairs of ultrasonic sensors 1, each including two sets of detection circuits 23, a filter circuit 24, an amplification circuit 25, and an A / D converter 26. The signals of the receiving elements 3a and 3b that have received the reflected waves 79a and 79b are detected by the detection circuits 23a and 23b, and only the Doppler shift signal component from which the ultrasonic carrier component (base component) is removed is extracted. The frequency components unnecessary for the A / D conversion process are removed by the filter circuits 24a and 24b, and amplified by the amplifier circuits 25a and 25b, respectively. The Doppler shift signal is an analog signal, but is converted into digital data by the A / D converters 26 a and 26 b and temporarily stored in the buffer memory 41.

  The calculation unit 51 includes a buffer memory 41 and a calculation processing device 43. The buffer memory 41 temporarily holds measurement data from the ultrasonic measurement unit 50. The data in each buffer memory is sent to the arithmetic processing unit 43 every fixed amount. The arithmetic processing unit 43 receives data from each sensor digitized by each A / D converter via the digital input unit 44, and performs arithmetic processing by the arithmetic functions of the signal arithmetic processing unit 45 and the general-purpose arithmetic processing unit 46. The blood flow velocity from which the noise component is removed is calculated. If the arithmetic processing unit 43 operates at a sufficiently high speed with respect to the sampling rate of the measurement data, the buffer memories 41 and 42 can be omitted. The signal arithmetic processing unit 45 is a device that performs signal processing at a high speed with a special hardware configuration. If the processing speed of the general-purpose arithmetic processing unit 46 is high, the signal arithmetic processing unit 45 can be omitted.

  The main storage unit 47 holds measurement data and calculation data used when the calculation processing device 43 executes calculation. Data that needs to be stored, such as measurement data and calculation result data, is stored in the storage 48. The storage 48 is configured by a nonvolatile flash memory device or a hard disk device.

The input / output device 49 is a device having a user interface function such as a keyboard and a mouse, a device having a communication function such as an Ethernet (registered trademark) or a serial communication bus, and the like. The display device 55 is a device having a screen display function such as a CRT device or a liquid crystal display device. Furthermore, as a peripheral device, a blood pressure measuring device is connected, and data can be corrected with a blood pressure value.

As shown in FIG. 3, the blood flow velocity is measured by bringing a living body 71 (in the embodiment, a fingertip of a subject) into contact with the blood flow sensor 10. The ultrasonic wave (transmission wave 78a) emitted from the transmitting element 2a of the ultrasonic sensor 1a propagates through the living tissue and is reflected by the blood flowing through the blood vessel. The reflected wave 14a changes to a signal subjected to Doppler shift according to the blood flow velocity. This reflection is received by the receiving element 3a. Similarly, for the ultrasonic sensor 1b, the ultrasonic wave (transmitted wave 78b) emitted from the transmitting element 2b is reflected by the Doppler shift due to blood flow and detected by the receiving element 3b, but the ultrasonic wave is emitted. Directional direction is different.
The signals of the reflected waves 79a and 79b received by the receiving elements 3a and 3b are detected by the detection circuits 23a and 23b, respectively, and only the Doppler signal component from which the ultrasonic carrier component (base component) is removed is extracted. Further, high frequency components unnecessary for A / D conversion processing are removed by the filter circuits 24a and 24b, and then amplified by the amplification circuits 25a and 26b, respectively. Although this Doppler signal is an analog signal, it is converted into digital data by the A / D converters 26a and 26b, temporarily stored in the buffer memory 42, and then transferred to the arithmetic processing unit 43 to the main storage unit 47 through the digital input unit. And memorized.

  If these measurement data are not immediately analyzed, they are stored in the external storage medium via the network of the storage 48 or the input / output device 49, which is an external storage attached to the device, and the time required for the analysis processing. Just take it out.

  The digital data of the respective Doppler signals of the ultrasonic sensor 1a and the ultrasonic sensor 1b obtained by the above measurement is subjected to frequency transformation by Fourier transform (FFT) processing in the signal arithmetic processing unit 45 and the general-purpose arithmetic processing unit 46 of the arithmetic processing unit 43. The data is converted into distribution (spectrum) data, and the frequency distribution data is stored in the main storage unit 47. Assuming that the sampling frequency of A / D conversion is fs = 20 kHz and the number of FFT processes is Nf = 256, the frequency distribution data every 0.0128 seconds is Nf = 512, and the frequency distribution is every 0.0256 seconds. (However, the number of FFT processing data and the time interval of the FFT processing do not necessarily match. For example, 256 pieces of data can be processed at intervals of 0.01 seconds.) is there).

  If the frequency shift obtained from the data of the ultrasonic sensor 1a by the above method is Fa and the frequency shift obtained from the data of the ultrasonic sensor 1b is Fb, the blood flow velocity Vh can be derived by the following equation.

Vh = cFa / 2Fscosθ (Formula 2)
here,
θ = atan ((− cos α−Fb / Fa) / sin α) (Formula 3)
α is an angle formed by directivity of emission and reception of ultrasonic waves of the two ultrasonic sensors, c is a sound velocity in the living body, and Fs is a transmission frequency (drive frequency) of the ultrasonic sensors.

  In addition, since the blood is pushed by the blood pressure P of the living body and flows, the blood flow velocity Vh is considered to be affected by the blood pressure of the living body. In order to correct the influence of blood pressure, the blood flow velocity Vh is divided by the maximum blood pressure Ph measured by a blood pressure measuring device. The value of Vh / Ph is referred to as a corrected blood flow velocity Vc for convenience.

Vc = Vh / Ph (Formula 1)
If the corrected blood flow velocity Vc is large, the blood fluidity in the living body is relatively high (low viscosity), and if the corrected blood flow velocity Vc is small, the blood fluidity is low (high viscosity). is there. However, when data of a plurality of individuals (subjects) is evaluated, there is an influence of individual differences (individual differences) in arterial blood vessel diameters, and there may be cases where variations in measured values become large.

In order to measure the arterial blood vessel diameter, an image capturing device 9 shown in FIGS. 2 to 5 is used. The image capturing device 9 is a means for obtaining a blood vessel image inside the living body 71 by capturing the light emitted from the lighting device 11 and transmitted through the living body 71. In the embodiment, the light emitting element 12 is a high-intensity LED having a wavelength of 860 nm. The transmitted light passes through the water in the living body and is partially absorbed by hemoglobin in the blood vessel, so that an image is formed on the image pickup device 6 through the lens 5 as a pixel with reduced luminance of the blood vessel portion. As the image sensor 6, a CCD image sensor or a CMOS image sensor having 350,000 pixels or more is used. Image data obtained by the image sensor 6 is temporarily stored in the buffer memory 31 and transferred to the image data processing device 32. The image data is processed by the arithmetic processing unit of the image data processing device 32, and the processing device 32 extracts the blood vessel diameter 94.
The blood vessel diameter detecting means is a program executed by the arithmetic processing unit of the image data processing device 32, and performs processing such as contrast enhancement and binarization on the image data transferred from the buffer memory to the processing memory. An arterial blood vessel diameter 94 (FIG. 10) is obtained from image data 90 shown as an example. The data of the arterial blood vessel diameter 94 is sent to the arithmetic processing unit 51 and used for correction of blood fluidity data.

  Here, the blood viscosity index Rh indicating the blood fluidity is newly defined as a value obtained by further correcting by correcting the corrected blood flow velocity Vc by the square of the blood vessel diameter d as follows.

Rh = Vc / (d × d) = Vh / Ph / (d × d) (Formula 4)
That is, the larger the Rh, the higher the blood fluidity, and the smaller the Rh, the lower the blood fluidity. However, the value of the blood vessel diameter d, which is considered to be a variation factor, is measured and corrected. Therefore, Rh can more accurately indicate blood fluidity than the corrected blood flow velocity Vc. Since the actual blood vessel diameter in the finger is considered to be about 0.5 mm to 1.5 mm, if this is not corrected, the data will vary by about 9 times, but the arterial blood vessel diameter will have an accuracy of plus or minus 10%. The viscosity index Rh can be measured with an accuracy of about plus or minus 20%.

If the processing capacity of the arithmetic processing device 43 is sufficiently large, the arithmetic processing device 43 may also serve as the function of the image processing device 32 without providing the image processing device 32 separately.
(Embodiment 2)
Since near-infrared light is also absorbed by venous blood, both the arterial image and the venous image may be included in the same image data as shown in FIG. It can be. Therefore, the second embodiment provides a means for solving this problem.

In the embodiment, the light emitting element 12 of the illumination device 11 has two wavelengths using an LED having a wavelength of 680 nm in addition to the wavelength of 860 nm. As shown in FIG. 13 , the light emitting elements of the respective wavelengths are caused to emit light alternately, and imaging is performed by the imaging element 6 at each timing, thereby obtaining different image data. Since light having a wavelength of 680 nm is a wavelength that is more easily absorbed by venous blood than arterial blood, image data in which an image of only a vein as shown in FIG. 9 is obtained. By subtracting the image data of FIG. 9 from the image data of FIG. 8 , only the arterial image remains, and the image data of the arterial image as shown in FIG. 10 is obtained, and the artery blood vessel diameter can be obtained therefrom.
(Embodiment 3)
The present invention addresses the same problems as those in the second embodiment. The image data of FIG. 6 is continuously photographed and recorded at regular time intervals of 0.1 seconds or less. As shown in FIG. 10, the temporal change in the luminance (or density) of each pixel of the continuous image data is a pulsating change in the pixel luminance of the arterial image (arterial region pixel luminance 84), while the tissue transmission region. The pixel luminance 83 and the vein region pixel luminance 87 have almost no regular pulsation like an arterial image. Therefore, by leaving only the pixels whose pulsation amplitude 85 is equal to or greater than a certain value and erasing pixels where no pulsation is observed, an image of only the artery as shown in FIG. 8 is obtained, and the arterial blood vessel diameter is obtained.
(Embodiment 4)
In the third embodiment, since some fluctuation occurs in the vein or a minute signal is detected, if any pulsation occurs in addition to the pixels in the arterial region due to noise mixing, simply evaluating the amplitude 85 It is considered that extraction of arterial images becomes difficult. Therefore, as the fourth embodiment, other pixels are erased while leaving only pixels having a period 86 synchronized with the pulsation period 82 of the blood flow velocity waveform 80 obtained by the blood flow velocity sensor 10 shown in FIG. Thus, an image of only the artery as shown in FIG. 8 is obtained, and the artery blood vessel diameter is obtained.
(Embodiment 5)
5, 6 and 7 schematically show a structure for supporting the illumination device 11 in the apparatus of the present invention.

  5 and 6 are diagrams illustrating examples of configurations in which the illumination device 11 can be fixed at an arbitrary position on the rail 101. FIG. In FIG. 5, the Example provided with two or more illuminating devices 11 is shown. The rail 101 is a member having a sufficient strength fixed to the apparatus main body. As shown in FIG. 6, the lighting device 11 is connected to the rail 101 via the clamp portion 102. The rail 101 and the clamp part 102 are fixed by tightening a fixing screw 103. You may fix with a spring-like member etc. besides a screw.

  FIG. 7 is a diagram illustrating an example of a configuration in which the illumination device 11 can be fixed at an arbitrary angle. The illuminating device 11 is fixed and supported by the support arm portion 111. The support arm 111 and the shaft 112 are fixed and attached to the bearing 113. The bearing 113 is fixed to the apparatus main body. The support arm 111 can take a free angle around the axis, and is fixed by tightening a fixing screw 114.

  With the configuration as described above, the illumination device 11 can be fixed at a position suitable for blood vessel image capturing. For example, a position where the bone tissue 74 is avoided.

  The present invention is not only capable of measuring blood fluidity (ease of flow) for the purpose of medical care and health maintenance / enhancement, but also the activity state of a living body (human body) and the blood flow state in each part of the living body It can also be used in measurement to know the correlation.

It is a block diagram which shows the structure of the measuring apparatus which concerns on this invention. FIG. A is a diagram showing a configuration of a sensor according to the present invention.

B is a diagram showing a configuration of a sensor according to the present invention.
It is a figure which shows the structure of the sensor which concerns on this invention. It is a figure which shows the structure of the sensor which concerns on this invention. It is a figure which shows the structure of the sensor which concerns on this invention. It is a figure which shows the structure of the apparatus which concerns on this invention. It is a figure which shows the structure of the apparatus which concerns on this invention. It is a figure which shows the example of the transmission image data of a biological body. It is a figure which shows the example of the transmission image data of a biological body. It is a figure which shows the example of the transmission image data of a biological body. It is a figure which shows a blood-flow velocity waveform. It is the figure which showed the pixel luminance waveform of the transmission image. It is a figure which shows the drive method of the light emitting element which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Ultrasonic sensor 2a, 2b Transmitting element 3a, 3b Receiving element 4 Sensor support member 5 Lens 6 Imaging element 7 Protective glass 8 Optical filter 9 Imaging device 10 Blood flow velocity sensor 11 Illuminating device 12 Light emitting element 13 Lens 14 Optical Filter 21 Transmission circuit 23a, 23b Detection circuit 24a, 24b Filter circuit 25a, 25b Amplification circuit 26a, 26b A / D converter 27 Amplification circuit 28 Filter circuit 29 A / D converter 31 Buffer memory 32 Image data processing device 41a, 41b Buffer memory 43 Arithmetic processing unit 44 Digital input unit 45 Signal calculation unit 46 General-purpose calculation unit 47 Main storage unit 48 Storage 49 I / O device 50 Ultrasonic measurement unit 51 Calculation unit 52 Blood pressure measurement device 53 Optical measurement unit 54 Peripheral device 55 Display Device 64 Voltage (a)
65 Drive voltage (b)
66 A / D conversion timing 71 Living body (fingertip)
72 Arterial blood vessel 73 Venous blood vessel 74 Bone tissue 78 Transmitted wave 79 Reflected wave 80 Blood flow velocity waveform 81 Blood flow velocity peak 82 Pulsation cycle 83 Tissue transmission region pixel luminance 84 Arterial region pixel luminance 85 Amplitude 86 Pulse cycle 87 Venous region pixel luminance 90 image data 91 tissue permeation region 92 vein region 93 arterial region 94 arterial blood vessel diameter 101 rail 102 clamp portion 103 fixing screw 111 support arm portion 112 shaft 113a bearing portion 113b bearing portion 114 fixing screw

Claims (11)

  Blood flow velocity measuring means for detecting and outputting information on blood flow velocity of blood flowing in the blood vessel in the living body, and blood vessel image observing means for imaging the blood vessel and outputting blood vessel diameter information from the obtained captured image And calculating means for calculating a blood viscosity index of the living body using information on the blood flow velocity output from the blood flow velocity measuring means and information on the blood vessel diameter output from the blood vessel image observation means, A biological information measuring device comprising:   The blood vessel image observation means includes an illuminating device that irradiates light into the living body, an imaging device that receives the light emitted from the illuminating device and passed through the living body, and outputs information on the blood vessel diameter; The biological information measuring device according to claim 1, wherein:   The image pickup device receives the light irradiated from the illumination device and passed through the living body and outputs image information for each pixel, and the image information output from the image pickup device portion is predetermined. The biological information measuring device according to claim 2, comprising: an image data processing device that outputs the blood vessel diameter information using an image processing technique.   The image information output from the image sensor unit includes a data value obtained by converting the intensity or phase of the light received for each pixel into a numerical value representing luminance or shading for each pixel. Item 4. The biological information measuring device according to Item 3.   The illumination device is capable of emitting infrared light, and the imaging device extracts a low-luminance region from the image information as an arterial blood vessel image and outputs information on the arterial blood vessel diameter. Item 5. The biological information measuring device according to any one of Items 2 to 4.   The illumination device can emit light of a plurality of wavelengths, respectively, and the imaging device extracts an image of an arterial blood vessel by performing a calculation while comparing the plurality of image information captured at different wavelengths, 5. The biological information measuring apparatus according to claim 2, wherein pixels other than the image of the arterial blood vessel are erased and information on the diameter of the arterial blood vessel is output.   The imaging apparatus accumulates image information captured continuously at fixed time intervals, detects luminance or light / dark time change information of each pixel of the image information, and the time change information of the luminance of the pixel is a living body. A case where a frequency component associated with a pulse is extracted as an image signal of an arterial blood vessel, image signals other than the image signal of the arterial blood vessel are deleted, and information on the arterial blood vessel diameter is output. Item 5. The biological information measuring device according to any one of Items 2 to 4.   The calculation means calculates the blood viscosity index from the peak value of the blood flow velocity and the arterial blood vessel diameter at the same time as the peak value of the blood flow velocity, and 6. The biological information measuring device according to any one of 6 above.   The calculation means accumulates the blood flow velocity information output from the blood flow velocity measurement means over a predetermined time, and extracts frequency information associated with a pulse from the accumulated blood flow velocity information. The biological information measuring device according to claim 1, comprising:   The blood flow velocity measuring means includes a pair of ultrasonic sensors including a transmitting means that makes an ultrasonic wave enter the living body and a receiving means that receives the reflected wave reflected by the blood in the living body. The biological information measuring device according to claim 1, wherein two pairs are provided on the substrate at mutually different angles.   The biological information measuring device according to claim 1, wherein the illumination device is provided so as to be movable with respect to an observation target.

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