JPS63242248A - Apparatus for measuring elastic characteristic of blood vessel - 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 [Field of Industrial Application] The present invention relates to a device for non-invasively measuring the elastic properties of arterial blood vessels using light.

[Conventional technology]

FIG. 4 shows a sensor section of a conventional non-invasive blood vessel elasticity measurement device. Measurement is performed by attaching the cuff 10 to a human finger as shown in the figure. As shown in FIG. 5, a light-emitting element 20 and a light-receiving element 30 are provided inside the cuff 10, and these are placed in contact with the finger via a transparent film 40, facing each other with the finger in between. . The inside of the cuff 10 is airtight, and by feeding air through the tube 50, the internal pressure is increased and the finger is compressed.

The light emitting element 20 emits near-infrared light (880 nm) with a wavelength that is more strongly absorbed by oxyhemoglobin than deoxyhemoglobin.
m ~ 940 nm) toward the inside of the finger. This light passes through the finger and reaches the light receiving element 30, where it is converted into an electrical signal. This signal has an amplitude corresponding to the amount of transmitted light, and since the light from the light emitting element 20 is absorbed by blood in the artery containing a large amount of oxyhemoglobin, it reflects the intravascular volume and volume pulse wave of the arterial system.

When air is sent into the cuff 10 and the finger is compressed, the intravascular volume and volume pulse wave of the arterial system change, and therefore the light receiving element 3
The signal from 0 also changes. The volume elastic modulus as an index of blood vessel elastic properties is calculated based on the change in this signal.

[Problem that the invention seeks to solve]

In the conventional blood vessel elasticity measurement device described above, the near-infrared light emitted by the light emitting element is also absorbed to some extent by deoxyhemoglobin. Therefore, in the process of compressing the finger with the cuff, in the low pressure region before the venous system is completely closed,
The amount of transmitted light is affected by the venous system, which contains a large amount of deoxyhemoglobin. As a result, the output signal of the light receiving element does not purely reflect the intravascular volume of the arterial system, and the intravascular volume of the arterial system is measured to be apparently large.

Therefore, in conventional blood vessel elasticity measurement devices, even if the output signal of the light receiving element accurately reflects the volume pulse wave of the young pig's vascular bed, the volume elastic modulus of the arterial blood vessel calculated based on this signal is actually is larger than the value of .

SUMMARY OF THE INVENTION An object of the present invention is to provide a blood vessel elastic characteristic measuring device that can solve such problems and obtain accurate volume elastic modulus of arterial blood vessels.

[Means for solving problems]

The present invention includes a light source that emits light toward the inside of a human finger;
A photodetector that receives the light from the light source that has passed through the human finger and outputs a signal with an amplitude corresponding to the amount of received light; a compression device that presses the human finger; and a compression device that compresses the human finger. In the blood vessel elasticity measurement device that calculates the elastic modulus of an arterial blood vessel based on the signal transmitted, the light source includes light source means for emitting two types of light with different wavelengths, and the photodetector emits the two types of light. A first method comprising a light detecting means for receiving light and outputting two signals having amplitudes corresponding to the amount of received light, and calculating the intravascular volume of the artery based on the two signals outputted by the light detecting means. 1. A second data processing means for calculating the elastic modulus of an arterial blood vessel using the intravascular volume determined by the first data processing means.

〔Example〕

Next, one embodiment of the present invention will be described.

FIG. 2 shows the sensor section of the non-invasive blood vessel elasticity measurement device of this embodiment. When performing measurements, a CAFFE compression device is attached to the human finger as shown in the figure.

As shown in FIG. 1, a light source 2 composed of two light emitting diodes and a photodetector 3 composed of two phototransistors are installed inside the cafe, and these are in contact with the finger through a transparent film 4. , placed opposite to each other with their fingers in between.

The interior of the cafe is made airtight, and air is pumped through the tube 5 to increase the internal pressure and compress the fingers.

The two light emitting diodes of the light source 2 each emit light of two types of wavelengths, which have different degrees of absorption by reduced hemoglobin and oxyhemoglobin, toward the inside of the finger. Photodetector 3
The phototransistor has a cylindrical light-receiving sensitivity for each of the two wavelengths of light emitted by the light source 2, receives the two types of light that have passed through the finger, and has an amplitude corresponding to the amount of transmitted light. Outputs two signals with light source 2
The amplitude of the two output signals of the photodetector 3 reflects the intravascular volume and plethysmography of the arterial system, since the light from the finger is absorbed by the oxyhemoglobin in the artery as it passes through the finger. However, since light with different wavelengths is used, the degree of reflection differs depending on the signal. Further, since the light from the light source 2 is also absorbed by deoxyhemoglobin, the two output signals of the photodetector 3 are affected by absorption in veins containing a large amount of deoxyhemoglobin. The degree of influence is
Because the wavelength of light is different, it differs depending on the signal.

The cuff pressure control section 6 has a near compressor, and appropriately sets the pressure inside the cuff based on a control signal from a system control section 10, which will be described later. Further, the cuff pressure control section 6 monitors the pressure within the cuff 1 and outputs the signal pc. The light amount control section 7 supplies current to the light emitting diode of the light source 2, and adjusts the amount of light emitted from it based on a control signal from the system control section 10.

As shown in FIG. 3, the signal processing section 8 includes amplification sections 81 and 82.
and filters 83 and 84. Amplifying sections 81 and 82 each amplify the two output signals of the photodetector 3 to a predetermined level and input them to filters 83 and 84, respectively.

Filters 83 and 84 filter the signals from amplifiers 81 and 82 to produce a direct current component DCI representing the intravascular volume.

It separates into DC2 and alternating current components ACI and AC2 representing the volume pulse wave, and outputs these to the data processing section 9.

The data processing unit 9 receives the direct current component DCI from the signal processing unit 8.
, DC2, AC components Act, AC2, and a signal indicating the pressure inside the cafe from the cuff pressure control unit 6 are first converted into digital data. Next, data reflecting only the absorption of light by arterial blood is calculated based on the data of the DC components DCI and DC2. As mentioned above, two different wavelengths
Since different types of light are used, the degree of absorption by arterial blood and venous blood differs depending on the light, and the degree to which the two DC components DCI and DC2 from the filters 83 and 84 reflect the absorption by these arterial and venous blood depends on the signal. It's different. Based on this difference, the data processing unit 9 obtains data that reflects only the absorption of light by arterial blood.

The data processing unit 9 then generates data reflecting only the absorption of light by this arterial blood, the AC components ACI, AC2 and the cuff 1.
Calculate vessel elastic modulus using internal pressure data. The calculation results are displayed on a display device and recorded or saved as necessary. The data processing unit 9 also calculates blood pressure and the like based on the above data, displays and records the calculation results, and stores the data in the same manner as the blood vessel elastic modulus.

The system control section 10 sends control signals to the cuff pressure control section 6 and the light amount control section 7 to control the internal pressure of the cafe and the light amount of the light source 2, respectively.

Next, the operation will be explained. When performing measurements, first, as shown in Fig. 2, a Caffe, which is a compression device, is attached to a human finger. The cuff pressure control unit 6 sends air into the cafe through the pipe 5 based on a control signal from the system control unit 10.

As a result, the pressure inside the cuff 1 gradually increases, and the finger is compressed. At this time, the cuff pressure control section 6 simultaneously measures the pressure inside the cafe and outputs a signal indicating the measurement result to the data processing section 9.

On the other hand, the light amount control section 7 supplies current to the light emitting diode of the light source 2, and adjusts the amount of light emitted from it based on the control signal from the system control section 10. As a result, the two light emitting diodes of the light source 2 each emit light of two types of wavelengths having different absorption levels by deoxyhemoglobin and oxyhemoglobin toward the inside of the finger. These lights pass through the fingers,
The light is received by the phototransistor of the photodetector 3. These phototransistors output two signals having amplitudes corresponding to the amounts of the two types of light transmitted through the finger.

The amplifying sections 81 and 82 of the signal processing section 8 each have a photodetector 3.
The two output signals are amplified to a predetermined level and output to filters 83 and 84. The filters 83 and 84 filter the signals from the amplifying section 8L 82 and separate them into direct current components DCI, DC2 representing intravascular volume and alternating current components ACI, AC2 representing volume pulse waves, and these are sent to the data processing section 9.
Output to.

The data processing unit 9 receives the direct current component DCI from the signal processing unit 8.
, DC2, AC components ACI, AC2, and a signal indicating the pressure inside the cuff 1 from the cuff pressure control section 6 are first converted into digital data. Next, data reflecting only the absorption of light by arterial blood is calculated based on the data of the DC components DCI and DC2. After that, data that reflects only the absorption of light by this arterial blood is converted to AC components C1 and AC2.
Then, the vascular elastic modulus is calculated using the data of the internal pressure of the cuff 1. The calculation results are displayed on a display device, and the data can be recorded or saved as necessary.

The data processing unit 9 also calculates blood pressure etc. based on the above data, and displays and records the calculation results as well as the vascular elastic modulus.
Save further.

〔Effect of the invention〕

As explained above, the present invention includes a light source that emits light toward the inside of a human finger, and a photodetector that receives light from the light source that has passed through the human finger and outputs a signal with an amplitude corresponding to the amount of received light. , a compression device that compresses a human finger, and a blood vessel elasticity measurement device that calculates the elastic modulus of an arterial blood vessel based on a signal obtained when the human finger is compressed by this compression device,
The light source includes light source means for emitting two types of light with different wavelengths, and the photodetector includes photodetection means for receiving two types of light and outputting two signals with amplitudes corresponding to the amounts of received light. , a first data processing means for calculating the intravascular volume of the artery based on the two signals outputted by the light detection means; second data processing means for calculating the ratio.

Therefore, according to the present invention, in the process of compressing a finger with a cuff, the intravascular volume of the arterial system can be measured without being influenced by the venous system even in a low pressure region before the venous system is completely closed. The accurate bulk modulus of elasticity can be determined.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a perspective view showing a part of the embodiment of FIG. 1, and FIG. 3 is a block diagram showing a part of the embodiment of FIG. 1. Figure 4 is a perspective view showing a part of the conventional device, and Figure 5 is a perspective view of a part of the conventional device.
FIG. 2 is a cross-sectional view of a portion of the illustrated device; 1...Cuff 2...Light source 3...Photodetector 4...Membrane 5...Tube 6...Cuff pressure control section 7... ... Light amount control section 8 ... Signal processing section 9 ... Data processing section IO ... System control section 81, 82 ... Amplification section 83, 84 ... Filter agent Patent attorney Yoshiyuki Iwasa: Figure 1 Figure 2 Figure 3 Figure 4 Photo-receiving element Figure 5 Procedural amendment 63.1.20 Showa Year Month Date

Claims (1)

[Claims] (1) A light source that emits light toward the inside of the human finger, a photodetector that receives the light from the light source that has passed through the human finger, and outputs a signal with an amplitude corresponding to the amount of received light, and presses the human finger. and a blood vessel elasticity measurement device that calculates the elastic modulus of an arterial blood vessel based on the signal obtained when a human finger is compressed by the compression device, wherein the light source emits two types of light with different wavelengths. The photodetector includes a light source means, the photodetector receives the two types of light, and the photodetector outputs two signals having amplitudes corresponding to the received amounts of the respective lights, and the photodetector outputs the above-mentioned signals. a first data processing means for calculating the intravascular volume of the artery based on two signals; and a second data processing means for calculating the elastic modulus of the arterial blood vessel using the intravascular volume calculated by the first data processing means. What is claimed is: 1. A blood vessel elastic characteristic measuring device comprising: data processing means.