JP3626010B2 - Continuous blood pressure monitor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous sphygmomanometer that continuously measures blood pressure by applying a weak vibration to a blood vessel in a living body and detecting and analyzing the vibration propagated through the blood vessel in the field of medical instruments.
[0002]
[Prior art]
Conventionally, in this type of continuous sphygmomanometer, a method for measuring blood pressure non-invasively in real time has been proposed as disclosed in, for example, Japanese Translation of PCT Publication No. 9-506024. This method uses the fact that the elasticity of the blood vessel changes according to the change in blood pressure, calculates the elasticity of the blood vessel by detecting the speed of vibration propagating through the blood vessel, and estimates the blood pressure from the elasticity value of the blood vessel. Is.
[0003]
Hereinafter, this blood pressure measurement method will be described. First, the blood vessel is vibrated from the body surface of the subject, and the vibration propagated on the blood vessel is detected. After the detected vibration is converted into a digital signal, filtering processing and phase detection processing are performed to calculate a phase change due to blood pressure fluctuation and obtain a change in vibration propagation speed. The change in vibration propagation speed represents a change in blood vessel elasticity, and the change in blood vessel elasticity represents a change in blood pressure, that is, dynamic pressure. By calibrating this change with the measured values of the maximum blood pressure and the minimum blood pressure by a cuff sphygmomanometer for calibration separately installed on the same subject, the blood pressure in the living body is measured non-invasively in real time. In order to perform highly accurate blood pressure detection in this method, it is important to efficiently transmit vibration to a blood vessel in a living body and detect vibration propagated through the blood vessel with high sensitivity.
[0004]
In the above Japanese National Publication No. 9-506024, the method shown in FIG. 7 is disclosed as an exciter for transmitting vibrations in a living body and a method for mounting the exciter. FIG. 7 shows a cross section of the exciter attached to the forearm and the components connected thereto. The exciter 101 is an inflatable bag connected to a compressor 103 and an electric-pressure converter 104 via an air tube 102 and is fixed by a stopper 105 so as to cover the radial artery 106. The compressor 103 generates a constant pressure that allows the exciter 101 to sufficiently compress the radial artery 106, and the electric-pressure converter 104 converts an electrical signal from a processor (not shown) into air pressure, and the radial artery 106 passes through the exciter 101. Vibrate.
[0005]
In the above Japanese National Publication No. 9-506024, the method shown in FIG. 8 is disclosed as a vibration sensor for detecting vibration propagated through a blood vessel and its mounting method. FIG. 8 shows a cross section of the vibration sensor attached to the wrist. The vibration sensor 107 is fixed near the radial artery 106 by a stopper 108. The stop 108 also includes a baffle 109 for reducing noise. The baffle 109 is an air bag for pressing the sensor 107 against the radial artery.
[0006]
[Problems to be solved by the invention]
However, since the conventional exciter is a system that vibrates blood vessels by air pressure, there are many compressors for creating compressed air, transducers for vibrating compressed air, and stoppers for press-contacting arms and air bags. The components are required. In addition, an electric-converter that vibrates compressed air must generate a large pressure fluctuation at a high frequency as a pressure fluctuation. For example, when a voice coil type converter is used, a power of several watts or more is required. And power consumption is large. In addition, in order to operate continuously for a long time, it is necessary to introduce a mechanism for suppressing overheating due to a radiator or the like, resulting in a large apparatus volume. Moreover, since it is necessary to squeeze the arm with a stopper, the subject is uncomfortable.
[0007]
The conventional vibration sensor requires a baffle and a fastener for pressing the vibration sensor against the arm at a constant pressure at all times. Since the arm and sensor are pressed with a stopper, if the subject moves the arm, the sensor may press the blood vessel and deform the blood vessel, which greatly distorts the propagation path of the vibration to be measured and is stable. It is difficult to obtain a blood pressure waveform. Moreover, since it is necessary to squeeze the arm with a stopper as in the case of the exciter, the subject is uncomfortable.
[0008]
The present invention has been made in view of the above-described conventional problems, and provides a continuous blood pressure monitor capable of efficiently transmitting vibrations to the body and detecting stably propagated vibrations without causing discomfort to the patient. The purpose is to do.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention arranges the exciter so that the radial artery 5 is sandwiched between the exciter and the bulge at the lower end of the wrist rib, and the vibration sensor is arranged on the heart side of the exciter. The vibration surfaces of the container and the vibration sensor are brought into contact with the human body with an adhesive material. Accordingly, vibration can be efficiently transmitted to the body without causing discomfort to the patient, and the stably propagated vibration can be detected.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, an exciter for vibrating a blood vessel is disposed so that the radial artery is sandwiched between the distal end portion of the human wrist and the vibration surface of the exciter, and the vibration sensor is the exciter. It is disposed on the skin on the upper side of the radial artery on the heart side, and the vibration surface of the exciter and the sensor surface of the vibration sensor are attached to the human skin with an adhesive material, and the back surface of the radial artery is the lower end of the radius Therefore, the vibration of the exciter is efficiently transmitted to the radial artery. Further, the vibration and the vibration surface of the exciter and the vibration sensor are adhered to the skin by the adhesive, so that the vibration can be propagated and detected more efficiently.
[0011]
The invention according to claim 2 is the invention according to claim 1, wherein the exciter is a monomorph vibrator composed of a metal plate and piezoelectric ceramics. As a result, it is possible to realize an exciter that is light and small and consumes less power.
[0012]
The invention according to claim 3 is the invention according to claim 1, wherein the vibration sensor is rectangular or elliptical, and its major axis is at least twice the diameter of the radial artery immediately below, and the major axis is the radius. It is arranged so as to be orthogonal to the artery. As a result, both ends in the long axis direction of the sensor are fixed on the skin, and only the center of the sensor located above the radial artery bends due to vibration of the radial artery, so even slight vibration of the radial artery can be detected with high sensitivity. It becomes.
[0013]
According to a fourth aspect of the present invention, in the first aspect of the present invention, the adhesive for attaching the exciter and the vibration sensor to the human skin is a double-sided tape. Thereby, it is possible to constitute a thin and uniform adhesive on the vibration surfaces of the exciter and the vibration sensor.
[0014]
The invention according to claim 5 is the invention according to claim 4, wherein the double-sided tape is provided with a narrow slit. Thereby, the air permeability of the bonding portion between the exciter and the vibration sensor can be ensured, and even when the sensor is worn for a long time, the exciter and the sensor can be prevented from peeling off due to peeling and sweating.
[0015]
Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a state in which an exciter and a vibration sensor of a sphygmomanometer according to Embodiment 1 of the present invention are attached to a living body forearm. The exciter 1 is adhered to the radial artery of the wrist, and the vibration sensor 2 is adhered to the heart side on the same radial artery. In order to describe these attachment positions and methods in more detail, a cross-sectional view in a plane passing through a straight line l (lowercase letter L) is shown in FIG.
[0016]
In FIG. 2, the exciter 1 and the vibration sensor 2 are bonded to the skin 6 directly above the radial artery 5 with double-sided tapes 3 and 4, respectively. The double-sided tapes 3 and 4 are made of a material harder than the radial artery 5. A rib lower end bulge 7 exists at the lower end of the rib, and a radial artery 5 exists directly under the skin 6. The exciter 1 is bonded to a position where the radial artery 5 is sandwiched between the lower rib ridges 7. The distance between the exciter 1 and the vibration sensor 2 is optimally about 2 to 10 cm. If the distance is smaller than this, the vibration propagation path is short, so the vibration propagation speed cannot be obtained accurately. Since it is large, vibration with sufficient amplitude cannot be detected in the vibration sensor 2.
[0017]
The configuration of the exciter 1 will be described in more detail with reference to FIG. FIG. 3 shows the cross section of the exciter 1 attached to the skin in detail. Similarly, a circular piezoelectric ceramic 11 is attached to a circular metal plate 10 having a diameter of about 20 mm, and electrodes (not shown) are respectively provided on the metal plate 10 and the piezoelectric ceramic 11 to constitute a monomorph type diaphragm. Silicon rubber 12 is bonded to the other surface of the metal plate 10 and is covered with a case 13. The outer surface of the silicone rubber 12 is an exciter vibration surface 8 and is adhered to the skin 6 by the double-sided tape 3. The exciter 1 having the above configuration is suitable for applying vibrations having a frequency of 100 to 3000 Hz to the radial artery.
[0018]
The configuration of the vibration sensor 2 will be described in more detail with reference to FIG. As shown in FIG. 1, in the present embodiment, the vibration sensor 2 has a rectangular shape and is arranged so that the long axis intersects the radial artery 5 perpendicularly. A tomogram on a plane passing through the straight line m is shown in FIG. This is a cross-sectional view of the vibration sensor 2 in the long axis direction. The vibration sensor 2 is adhered to the skin on the radial artery 5 with a double-sided tape 4. In the present embodiment, the long axis of the vibration sensor 2 is about four times as long as the radial artery 5 directly below. The vibration sensor 2 can be divided into three regions from the positional relationship with the radial artery 5, which are a region b on the radial artery and regions a and c on both sides thereof. The region b is located immediately above the radial artery 5 and vibrates in accordance with the vibration of the radial artery 5. On the other hand, since the regions a and c are located away from the radial artery 5, they are fixed to the skin without receiving vibration of the radial artery. Therefore, the vibration sensor 2 generates a large deflection in the major axis direction, and thereby the vibration sensor 2 can generate a large voltage. As the vibration sensor 2, the monomorph type diaphragm described in the configuration of the exciter 1, a piezoelectric polymer material, or the like is suitable.
[0019]
Next, the effect of the arrangement of the exciter 1 will be described. The exciter vibration surface 8 is deformed up and down by the excitation waveform. Deformation due to vibration of the exciter vibration surface 8 is transmitted to the radial artery 5 via the double-sided tape 3. Since the radial artery 5 is supported on the back by a hard radial lower end bulge 7, all the deformation energy emitted from the exciter vibration surface 8 is used for the deformation of the radial artery 5. Therefore, vibration energy can be efficiently transmitted to the radial artery 5.
[0020]
Next, the effect of the double-sided tape 3 will be described. As described above, the exciter vibration surface 8 is deformed up and down. The downward deformation is transmitted by compressing the skin, while the upward deformation is transmitted by the adhesive force of the double-sided tape. Thereby, vibration can be efficiently transmitted to the radial artery 5 without applying the exciter 1 to the skin. The same applies to the effect of the double-sided tape 4. The vibration of the radial artery 5 can be efficiently transmitted to the vibration sensor 2 without pressurizing the vibration sensor 2 against the skin. Furthermore, since it is not necessary to press the sensor against the blood vessel with a fastener or the like, a stable blood pressure waveform can be obtained without deforming the blood vessel even when the subject moves his arm.
[0021]
As described above, according to the first embodiment of the present invention, the exciter 1 has the advantages that the configuration is much simpler, lighter and smaller than the conventional exciter. In addition, the power consumption is small, and the entire device including the drive circuit of the exciter can be miniaturized. Furthermore, by applying a sine wave having an effective voltage of about 10V to the exciter 1, sufficient vibration can be applied to the radial artery 5 directly below, and the vibration sensor 2 can sufficiently generate vibration transmitted through the radial artery 5 with sufficient sensitivity. Detection is possible. Furthermore, since the sensor is not pressed against the blood vessel with a fastener or the like, the blood vessel is not deformed even if the subject moves the arm, and a stable blood pressure waveform can be obtained even if the subject moves the arm.
[0022]
Further, according to the first embodiment, the surface that contacts the skin with the silicon rubber 12 is made of a soft material, so that the degree of adhesion with the skin can be increased and the vibration of the metal plate 10 can be efficiently transmitted to the skin 15. it can. The silicon rubber 12 also serves as an insulating material.
[0023]
(Embodiment 2)
FIG. 5 shows the configuration of the double-sided tape according to Embodiment 2 of the present invention, and is a view of the exciter with the double-sided tape attached as seen from the bottom. The double-sided tape 20 affixed to the bottom surface of the exciter 1 is provided with a narrow slit. FIG. 6 shows a cross-sectional view when the exciter 1 is attached to the arm. The exciter 1 is adhered to the skin 6 with a double-sided tape 20. The double-sided tape 20 is provided with a slit 21, which serves as an airway and allows sweating from the skin to be released to the outside air. In the above description, the double-sided tape for mounting the exciter 1 has been described, but the same configuration can be applied to the double-sided tape for mounting the vibration sensor 2.
[0024]
As described above, according to the double-sided tape according to the second embodiment of the present invention, even when the exciter 1 and the vibration sensor 2 are adhered to the arm for a long time and blood pressure is measured, the adhesive part is peeled off due to sweating and peeled off. Can be prevented, and blood pressure can be measured for a long time.
[0025]
In the second embodiment, the slit 21 has been described as being unidirectional. However, the slit may have any shape such as a shape that intersects in the vertical and horizontal directions.
[0026]
【The invention's effect】
As is clear from the above description, according to the present invention, the exciter is disposed so as to sandwich the radial artery between the rib and the exciter, and the vibration surfaces of the exciter and the vibration sensor are adhered to the skin with an adhesive. Therefore, vibration can be efficiently applied to the radial artery, and vibration transmitted through the radial artery can be detected with high sensitivity. In addition, the drive circuit for driving the exciter can be made small, and a small and lightweight continuous blood pressure system can be realized. Furthermore, since the sensor is not pressed against the blood vessel with a fastener or the like, the blood vessel is not deformed even if the subject moves the arm, and a stable blood pressure waveform can be obtained even if the subject moves the arm.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a method for attaching an exciter and a vibration sensor for a sphygmomanometer according to Embodiment 1 of the present invention. FIG. 2 shows a method for attaching an exciter and a vibration sensor for a sphygmomanometer according to Embodiment 1. FIG. 3 is a cross-sectional view illustrating the configuration of the exciter of the sphygmomanometer according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the configuration of the vibration sensor of the sphygmomanometer according to the first embodiment. FIG. 6 is a front view showing the shape of a double-sided tape attached to the exciter of the sphygmomanometer according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view illustrating the configuration of the exciter and double-sided tape of the sphygmomanometer according to Embodiment 2. FIG. 7 is a cross-sectional view showing the configuration and mounting method of a conventional sphygmomanometer exciter. FIG. 8 is a cross-sectional view showing the configuration and mounting method of a conventional sphygmomanometer vibration sensor.
DESCRIPTION OF SYMBOLS 1 Exciter 2 Vibration sensor 3 Double-sided tape 4 Double-sided tape 5 Radial artery 6 Skin 7 Raising of lower end of radius 8 Exciter vibration surface

Claims (5)

It is equipped with an exciter for vibrating a blood vessel, a vibration sensor that detects vibration propagated through the blood vessel, and a processor that analyzes an electrical signal from the vibration sensor, and continuously measures the blood pressure of the human body by measuring the vibration propagation speed. In an apparatus for measuring in a non-invasive manner, an exciter for vibrating a blood vessel is disposed so that the radial artery is sandwiched between the distal end of the human wrist and the vibration surface of the exciter, and the vibration sensor is the exciter. A continuous sphygmomanometer, which is disposed on the skin above the radial artery on the heart side, and the vibration surface of the exciter and the sensor surface of the vibration sensor are attached to the human skin with an adhesive. 2. The continuous blood pressure monitor according to claim 1, wherein the exciter is a monomorph vibrator composed of a metal plate and piezoelectric ceramics. 2. The vibration sensor according to claim 1, wherein the vibration sensor is rectangular or elliptical and has a long axis that is at least twice the diameter of the radial artery directly below and the long axis is orthogonal to the radial artery. Continuous blood pressure monitor. 4. The continuous blood pressure monitor according to claim 1, wherein the adhesive for attaching the exciter and the vibration sensor to human skin is a double-sided tape. The continuous blood pressure monitor according to claim 4, wherein a narrow slit is provided in the double-sided tape.

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