JPH0219141A - Blood vessel diameter measuring instrument - Google Patents

Abstract

PURPOSE:To easily measure the diameter of a blood vessel in an organism by obtaining a relation between the arrangement positions of many pressure sensitive elements of a pulse wave sensor and the minimum value of a pressure pulse wave and obtaining a pair of peak intervals to appear along the arranging direction of the pressure sensitive elements. CONSTITUTION:The pulse wave sensor have a pressing surface where many pressure sensitive elements are arranged, and it is pressed onto an artery on an organism surface so that the arranging direction of the pressure sensitive elements can be crossed to the artery. A peak interval detecting means obtains the relation between the arrangement positions of many pressure sensitive elements so as to be crossed to the artery and the minimum value of the pressure pulse wave detected from the pressure sensitive elements, respectively, and simultaneously, the means obtains a pair of intervals of the peaks to appear along the arranging direction of the pressure sensitive elements in the relation. A blood vessel diameter deciding means decides the diameter of the tery based on the peak interval obtained by the peak interval detecting means.

Description

TECHNICAL FIELD The present invention relates to a blood vessel diameter measuring device for measuring the diameter of an artery.

Prior Art Conventionally, medical information such as cardiac output, blood pressure, and blood oxygen saturation has been continuously measured in order to monitor a patient's hemodynamics during or after surgery. Instead of directly measuring cardiac output, the amount of blood flowing through blood vessels at a specific site such as the patient's wrist (this blood flow corresponds to cardiac output) is measured. There is.

In this case, for example, the blood flow velocity is detected by the so-called Doppler method by emitting ultrasonic waves from the skin surface toward the blood vessels in the living body, and the blood flow velocity is compared with a predetermined constant cross-sectional area in the blood vessel direction. A so-called ultrasonic flowmeter is known that measures blood flow based on .

Problems to be Solved by the Invention However, since the flow cross-section within a blood vessel differs from person to person, using a fixed value does not provide sufficient accuracy in measuring blood flow. On the other hand, when determining the intravascular cross-sectional area for each measurement, it is possible to determine the diameter (inner diameter) of each individual's blood vessels, but it is not necessarily easy to measure the diameter of blood vessels in a living body. Therefore, there has been a demand for a blood vessel diameter measuring device that can easily measure the diameter of blood vessels in living bodies.

First Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is to measure the diameter of an artery located near the surface of a living body. A blood vessel diameter measuring device comprising a first
As shown in the claim correspondence diagram in the figure, (a) it has a pressing surface on which a large number of pressure sensing elements are arranged, and the pressure sensing elements are arranged on the artery on the surface of the living body so that the arrangement direction thereof intersects with the artery. Determining the relationship between the pressed pulse wave sensor, (b) the array position of a large number of pressure sensing elements arranged to intersect with the artery, and the lowest value of the pressure pulse wave detected from each of the pressure sensing elements. (C) a peak interval detection means for determining the interval between a pair of peaks appearing along the arrangement direction of the pressure sensitive elements in this relationship; and (C) a diameter of the artery based on the peak interval determined by the peak interval detection means. and means for determining a blood vessel diameter.

Operation and Effects of the First Invention According to the blood vessel diameter measuring device configured as described above, the peak interval detection means detects the arrangement positions of a large number of pressure sensitive elements arranged to intersect with the arteries of the pulse wave sensor and their pressure sensitive elements. The relationship between the minimum value of the pressure pulse wave detected from each element is determined, and the interval between a pair of peaks appearing along the arrangement direction of the pressure-sensitive elements is determined. Since the diameter of the artery is determined based on the peak interval determined by the interval detection means, the diameter of the artery within the living body can be easily determined by simply pressing the pulse wave sensor onto the artery on the surface of the living body. Can be measured.

Second Means for Solving the Problems The second invention also provides a blood vessel diameter measuring device for measuring the diameter of an artery located near the surface of a living body, and the claim of FIG. As shown in the corresponding diagram, (a) it has a pressing surface on which a large number of pressure-sensitive elements are arranged, and is pressed onto the artery on the surface of the living body so that the arrangement direction of the pressure-sensitive elements intersects with the artery; a pulse wave sensor; (b) relationship detection means for determining the relationship between the arrangement positions of a large number of pressure sensing elements arranged to intersect with the artery and the amplitude of the pressure pulse wave detected from each of the pressure sensing elements; , (C) blood vessel diameter determining means for determining the diameter of the artery based on the relationship determined by the relationship detecting means.

Operation and Effects of the Second Invention According to the blood vessel diameter measuring device configured as described above, the relationship detection means detects the array positions of a large number of pressure sensitive elements arranged to intersect with the artery of the pulse wave sensor and the pressure sensitive elements. While the relationship between the amplitude of the pressure pulse wave and the amplitude of the pressure pulse wave detected from
By simply pressing the pulse wave sensor onto the artery on the surface of the living body, the diameter of the artery within the living body can be easily measured.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 3 shows an example of a blood flow measuring device that measures blood flow using the blood vessel diameter measuring device of the present invention. In the figure, reference numeral 10 denotes a container-shaped housing, which is detachably attached to the wrist 12 of a human body with a band (not shown) with its open end facing the surface 14 of the wrist 12. Inside the housing IO, a pulse wave sensor 20 is provided via a diaphragm 18 so as to be relatively movable and protrude from the open end of the housing 10, and a pressure chamber 22 is formed by the housing 10 and the diaphragm 18. ing.

In this pressure chamber 22, a pressure regulating valve 26 is connected to a fluid supply source 24.
A pressurized fluid such as pressurized air is supplied through the pressure chamber 22, whereby the pulse wave sensor 20 is pressed against the surface 14 with a pressing force corresponding to the pressure within the pressure chamber 22.

The pulse wave sensor 20 is composed of a large number of pressure sensitive elements (not shown) such as pressure sensitive diodes arranged on a pressing surface 28 of a semiconductor chip made of, for example, single crystal silicon. By being pressed so that the arrangement direction is substantially perpendicular to the radial artery 32, a pressure vibration wave, that is, a pressure pulse wave, generated from the radial artery 32 and transmitted to the surface 14 is detected. In this embodiment, the radial artery 32 corresponds to the artery. The distance between each pressure-sensitive element in the direction substantially orthogonal to the radial artery 32 is sufficiently small (set) so that a necessary and sufficient number of pressure-sensitive elements are arranged on the radial artery 32. The electrical signal output from the pressure element, ie, the pulse wave signal SM representing the pressure pulse wave, is supplied to the control device 34.

An ultrasonic transducer 36 is integrally attached to the outer peripheral surface of the side wall of the housing 10. Ultrasonic transducer 36 is fixed to housing 10 and is attached to wrist 12 when housing 10 is attached to wrist 12.
A main body 37 made of resin whose flat surface facing 2 is brought into close contact with the surface 14 of the wrist 12, and a transmitter 38 embedded within the main body 37 that emits ultrasonic waves and receives reflected waves of the ultrasonic waves. It is configured with a wave receiver 39,
By outputting a drive signal SD from the control device 34 to the oscillator 40, the wave transmitter 38 tilts toward the radial artery 32 by a predetermined angle (θ) from the downstream side to the upstream side of the radial artery 32. In this state, an ultrasonic wave having a predetermined frequency f0 is emitted, and the reflected wave of the emitted ultrasonic wave from the radial artery 32 is received by the receiver 39, and a reflected wave signal SR representing the reflected wave is transmitted via the amplifier 42. and is supplied to the control device 34.

The control device 34 includes a microcomputer and controls the pressure in the pressure chamber 22 by outputting a drive signal SD to the drive circuit 44 and controlling the pressure regulating valve 26 according to a predetermined program. The pressure pulse waves outputted from the plurality of pressure sensing elements are detected, and the relationship between the lowest value of the pressure pulse waves and the arrangement position of the pressure sensing elements is determined, and the radial artery 32 is adjusted based on the relationship. While determining the radius r within, the drive signal SD is output to the oscillator 40 to cause the ultrasonic transducer 36 to emit an ultrasonic wave toward the radial artery 32, and the frequency f0 of the ultrasonic wave and the radius r from the radial artery 32 are determined. The blood flow velocity V in the radial artery 32 is determined based on the average frequency f3 of the reflected wave, which will be described later, and the blood flow IIF in the radial artery 32 is determined from this blood flow velocity V and the radius r.
is calculated and the blood flow rate F is displayed on the display 46.

Next, the operation of the blood flow measuring device configured as described above will be explained according to the flowchart of FIG. 4.

First, when a starting switch (not shown) is operated, step S1 is executed to increase the pressure in the pressure chamber 22 at a relatively slow constant rate, and step S2 is executed to complete the rate-limiting pressure increase process. At , detection of pulse wave signals SM from the plurality of pressure sensitive elements is started. Next, step S3 is executed, and the pressure P in the pressure chamber 22 is
is a predetermined constant pressure P, (for example, 180 mm1
It is determined whether the pulse wave signal SM has reached 1 g), and if it has not reached it yet, steps S1 to S3 are repeatedly executed, and in step S2, the pulse wave signal SM is sequentially detected and recorded together with the pressure P in the pressure chamber 22. However, at a constant pressure P,
If it is determined that the pressure has been reached, the pressure inside the pressure chamber 22 is evacuated in step S4.

FIG. 5 shows the relationship between the magnitude (mV) of the pulse wave signal SM detected from, for example, one predetermined pressure sensitive element among a large number of pressure sensitive elements and the pressure P in the pressure chamber 22. It is something that Next, by executing step S5, the amplitude A of each pressure pulse wave collected from the predetermined - number of pressure sensitive elements is calculated. FIG. 6 shows the relationship between the amplitude A of each pressure pulse wave and the pressure P in FIG. 5 using a curve.

Next, by executing step S6, the pressure P in the pressure chamber 22 for measuring the radius r in the radial artery 32 is
1 is determined. This pressure P1 is the pressure when the radial artery 32 is almost crushed as shown in FIG. 7, and the amplitude is considerably small. For example, as shown in FIG. 6, the maximum amplitude A m 1/10 from a x
amplitude (0, 1A, .

) is determined as pressure P. In the following step S7, the pressure P is determined from among the pulse wave signals SM stored in step S2.

, the pulse wave signals SM detected from the plurality of pressure sensing elements are read, the minimum value of each pressure pulse wave represented by these pulse wave signals SM is determined, and the minimum value of the pressure pulse wave and the pressure sensing element are calculated. The relationship with the arrangement position of the elements is determined. FIG. 8 shows an example of this relationship using a curved line. Next, step S8 is executed to obtain the interval between a pair of peaks appearing along the arrangement direction of the pressure sensitive elements in the relationship obtained in step S7, while step S9 is executed and step The radius r within the radial artery 32 is based on the peak interval determined in S8.
is determined. That is, when the radial artery 32 is almost crushed under the pressure P as shown in FIG. 7, the width L2 inside the radial artery 32 in FIG. 7 corresponds closely to the peak interval LI. has been experimentally confirmed, and the width L2, that is, the peak interval L1, is approximately equal to πr, so the radius r is determined by the following equation (1). Therefore, in this embodiment, steps S7 and S8 correspond to the peak interval detection means, and step S9 corresponds to the blood vessel diameter determination means. Furthermore, (1)
In the formula, a is a correction constant determined in advance.

ra-a-L1/π...(1) Next, by executing step 310, an ultrasonic wave having a frequency of f0 is sent from the transmitter 38 of the ultrasonic transducer 36 toward the radial artery 32 in advance. Based on a reflected wave signal SR representing a reflected wave that is continuously emitted for a predetermined period of time, for example, 5 seconds, and is reflected by blood in the radial artery 32 and received by the delivery device 39, The average frequency r of the waves is determined. Next, by executing step Sll, the blood flow velocity V is calculated according to the following equation (2).

However, C: Speed of sound in blood θ: Ultrasonic emission angle Next, by executing step SI2, the radius r in the radial artery 32 determined in step S9 and the radius r calculated in step S11 Based on the blood flow velocity ■, the blood flow F is calculated from the following equation (3). Subsequently, by executing step S13, the calculated blood flow 31F
is displayed on the display 46, by repeating steps 310 and subsequent steps again, the blood flow velocity V is continuously detected at predetermined time intervals, and the blood flow IF is sequentially measured and displayed. becomes.

F = v The relationship between the lowest value of the pressure pulse waves detected from each pressure element is determined, and the interval between a pair of peaks appearing along the arrangement direction of the pressure sensitive elements in that relationship is determined, and the peak interval L1 Since the radius r inside the radial artery 32 is determined based on , the radius r in the radial artery 32 in the wrist 12 can be easily measured, and the blood flow rate F can also be easily measured accordingly.

Further, according to this embodiment, the ultrasonic transducer 36
is attached to a housing 10 in which a pulse wave sensor 20 is provided, and its ultrasonic transducer 3
6 toward the portion of the radial artery 32 located near the pulse wave sensor 20, the housing 10
By simply attaching it to the wrist 12, the ultrasonic transducer 36 can be placed on the radial artery 32 at the same time as the pulse wave sensor 20, and the blood flow velocity can be detected at a portion -i close to the radius measurement site of the radial artery 32. There are advantages.

In the above embodiment, the pulse wave sensor 20 is used only to determine the radius r inside the radial artery 32, but in addition, in step S4, the pulse wave sensor 20 is used to determine the radius r inside the radial artery 32.
The pressure P in the pressure chamber 22 is held at the pressure corresponding to the maximum amplitude A, X, without discharging the pressure inside, and in this state, pressure pulse waves are sequentially detected, and the detected pressure pulse waves are displayed. Alternatively, the blood pressure value may be determined and displayed based on a predetermined relationship based on the detected pressure pulse wave or the like.

In addition, in the above-mentioned example, the blood flow velocity V is detected based on the average frequency 11 of the reflected waves of ultrasound waves emitted continuously for 5 seconds, so the blood flow velocity V represents the average flow velocity. However, it does not necessarily have to be the average flow velocity, and the instantaneous blood flow velocity may be detected by instantaneously emitting ultrasonic waves.

Furthermore, in the above embodiment, the relationship between the arrangement position of the pressure sensitive elements and the lowest value of the pressure pulse wave is determined at the pressure P1 corresponding to an amplitude of 0.1 A. It is also possible to determine the above relationship at a predetermined pressure P, which is smaller than . In this case, the correction constant a in equation (1) is changed, or a relational expression between the peak interval and the radius r in the relationship determined for the pressure P is determined separately experimentally. That will happen.

Further, in the above-mentioned embodiment, the radius r inside the radial artery 32 is determined based on the relationship between the arrangement position of the pressure-sensitive elements and the lowest value of the pressure pulse wave, but it is not necessary to configure it in this way. For example, as shown in FIG. 9, steps S7 to S9 in the flowchart of FIG.
and SS2 may be provided. In step SSI, the pulse wave signals SM detected from each pressure sensitive element at the pressure P and stored in the step S2 are read, and the amplitude A' of the pressure pulse wave represented by these pulse wave signals SM is read. is obtained for each pressure-sensitive element,
Arrangement position of pressure sensitive elements and amplitude A of pressure pulse wave at pressure P1
'' is determined. FIG. 10 shows an example of that relationship as a curve. In step S82, the maximum amplitude A II M X '' behind the amplitude A' is determined, and Its maximum amplitude A a 11 X'
A pair of amplitudes obtained by multiplying by 0.1 (0, 1A, ,
The distance L3 in the pressure sensitive element arrangement direction between the two spaces L3 is determined, and the radius r is determined based on this distance in the same manner as in the previous embodiment. This interval L3 is also the width L3, similar to the peak interval LI in the above-described embodiment.
It has been experimentally confirmed that it is approximately equal to 2. In this embodiment, step SS1 corresponds to the relationship detection means, and step SS2 corresponds to the blood vessel diameter determination means.

Furthermore, in the above embodiment, the radius r inside the radial artery 32 is measured in order to measure the blood flow, but it is also possible to just measure the radius r and the diameter without measuring the blood flow. Alternatively, values other than the blood flow rate may be determined based on the radius r or diameter. In this case, it is also possible to configure the device to measure the outer diameter of the radial artery 32 instead of measuring the inner diameter of the radial artery 32.

Further, in the above-mentioned embodiments, a pressure-sensitive element such as a pressure-sensitive diode is used, but a semiconductor element such as a pressure-sensitive transistor or a pressure-sensitive resistor may be used, or another pressure-sensitive element other than a semiconductor element may be used. It may be.

Further, in the above embodiment, the radius r of the radial artery 32 and the like are measured, but it is of course possible to measure other arteries other than the radial artery, such as the carotid artery and the dorsalis pedis artery.

In addition, various changes may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIGS. 1 and 2 are claims correspondence diagrams, respectively. FIG. 3 is a circuit diagram showing an example of a blood flow measuring device that measures blood flow using the blood vessel diameter measuring device of the present invention. FIG. 4 is a flowchart for explaining the operation of the apparatus shown in FIG. FIG. 5 is a diagram showing an example of the relationship between the magnitude of the pulse wave signal output from the pressure sensing element and the pressure in the pressure chamber. FIG. 6 is a diagram showing the relationship between the amplitude of the pressure pulse wave and the pressure in the pressure chamber in FIG. 5. FIG. 7 is a diagram showing an example of a state in which the radial artery is crushed. FIG. 8 is a diagram showing an example of the relationship between the arrangement position of the pressure sensitive elements and the lowest value of the pressure pulse wave. FIG. 9 is a diagram showing a part of a flowchart showing the operation of another example of the present invention, which replaces some of the steps in FIG. 4. FIG. 10 is a diagram showing an example of the relationship between the arrangement position of the pressure sensitive elements and the amplitude of the pressure pulse wave in the embodiment of FIG. 9. 28: Pressing surface 32: Radial artery (artery) Step 37.38: (Peak interval detection means) Step S9. SS2: (Vessel diameter determining means) Step S81:
(Related detection means) Applicant Korin Electronics Co., Ltd. 14; Surface 20: Pulse wave sensor Figure 1 Figure 5 Pressure P in pressure list 22 Figure 6 Figure 7

Claims (2)

[Claims] (1) A blood vessel diameter measuring device for measuring the diameter of an artery located near the surface of a living body, which has a pressing surface on which a large number of pressure-sensitive elements are arranged, and the pressure-sensitive element is placed on the artery on the surface of the living body. a pulse wave sensor that is pressed so that its arrangement direction intersects with the artery, the arrangement positions of a large number of pressure-sensitive elements arranged so as to intersect with the artery, and the pressure pulse waves detected from each of the pressure-sensing elements. a peak interval detection means for determining a relationship with the lowest value of and determining an interval between a pair of peaks appearing along the arrangement direction of the pressure sensitive elements in the relationship; and a peak interval detection means based on the peak interval determined by the peak interval detection means. A blood vessel diameter measuring device comprising: blood vessel diameter determining means for determining the diameter of the artery. (2) A blood vessel diameter measuring device for measuring the diameter of an artery located near the surface of a living body, comprising a pressing surface on which a large number of pressure-sensitive elements are arranged, and the pressure-sensitive element is placed on the artery on the surface of the living body. a pulse wave sensor that is pressed so that its arrangement direction intersects with the artery, the arrangement positions of a large number of pressure-sensitive elements arranged so as to intersect with the artery, and the pressure pulse waves detected from each of the pressure-sensing elements. A blood vessel diameter measuring device comprising: a relationship detecting means for determining a relationship between the amplitude of and a blood vessel diameter determining means for determining the diameter of the artery based on the relationship determined by the relationship detecting means.