JP3940150B2 - Caffres electronic blood pressure monitor - Google Patents

Description

  The present invention relates to an electronic sphygmomanometer, and particularly to an apparatus that is ultra-compact and that is easily mounted on a wrist or finger of a subject to easily measure blood pressure.

In the conventional electronic blood pressure monitor, the oscillometric method is mainly used. In the oscillometric method, the blood vessel is compressed with a cuff wrapped around the upper arm or wrist, and the maximum blood pressure (systolic blood pressure: SBP) and the minimum blood pressure (dilated) are determined from the behavior of the cuff pressure fluctuation reflecting the vibration of the blood vessel wall depending on the arterial pressure. Blood pressure: DBP). In the slow decompression process of the cuff, this vibration waveform increases near the systolic blood pressure and becomes maximum at the mean blood pressure, and then becomes a substantially constant amplitude around the diastolic blood pressure. In general, the algorithm for determining the systolic blood pressure and the systolic blood pressure is based on the threshold value K1 of 0.5 on the high cuff pressure side, for example, 0.5 on the low cuff pressure side with respect to the maximum amplitude of the small fluctuation waveform of the cuff pressure obtained in the slow decompression process of the cuff. In this case, the threshold K2 is set to 0.7, for example, and the pressure sensor values corresponding to the threshold K2 are set to the maximum blood pressure and the minimum blood pressure. The thresholds K1 and K2 are determined so as to coincide with values of a direct method of inserting a pressure sensor into an artery and an auscultation method of listening to Korotkoff sounds, but are not based on a clear and strict principle. Further, in the conventional method using a cuff to compress a blood vessel, a pressurizing pump must be operated as a means for pressurizing the cuff, so that electric power is required and a large battery is used. Furthermore, even if the artery is crushed with a pressure corresponding to the maximum blood pressure, the artery is not completely occluded at both ends of the cuff in principle, so the pressure pulse wave of the artery propagating there is transmitted to the cuff, and the cuff pressure In the algorithm for determining the maximum and minimum blood pressure with the threshold values K1 and K2 as a minute fluctuation, it appears in the signal of the pressure sensor, and an accurate blood pressure cannot be determined because of the remaining pressure pulse wave component. In addition, because the entire upper arm or wrist is pressurized, anatomical structures such as bones and tendons can prevent the arteries from being completely tightened even if excessive pressure is applied, which can interfere with accurate blood pressure measurement. There were many. As a means of overcoming the problems of these conventional cuff pressurization methods, the position of the wrist radial artery is accurately detected by palpation, a pressure sensor is fixed at that position, and the blood vessel is pressed by the technique, so-called applanation method A method for measuring the pressure inside the blood vessel based on the above is disclosed (for example, see Patent Document 1).
JP 2001-514916 (pages 17-19, FIG. 1)

  However, since the applanation method in the prior art is inherently sensitive to the position where the blood vessel is pressed, it is possible to accurately measure the blood pressure with the conventional measurement method described in Patent Document 1. However, it was limited to doctors and nurses who were skilled in watching these pulses, and not everyone could measure blood pressure accurately and easily.

(Object of invention)
An object of the present invention relates to an electronic sphygmomanometer, and in particular, to provide a device that is ultra-compact and can be easily and accurately measured by anyone by wearing it on the wrist or finger of a subject.

In order to achieve the above object, the blood pressure monitor of the present invention employs the following means.
A caffres electronic sphygmomanometer comprising a pressure detecting unit in contact with a living body surface, a pulse wave detecting unit having a photoelectric sensor, and a blood pressure determining unit, and detecting a pulse wave of a wrist radial artery, a sphygmomanometer body, and a light / pressure sensor unit And a pressurizing unit that pressurizes the wrist radial artery with a finger through the light / pressure sensor unit, and the blood pressure determining unit uses a volume vibration method.

  The light / pressure sensor unit includes a base portion made of an elastic member, and a pressure detection unit and a pulse wave detection unit embedded in the base unit.

  The light / pressure sensor unit is provided on the ring.

  The base portion of the light / pressure sensor unit is made of an elastic member having a Young's modulus of 2 MPa to 100 MPa.

  The sphygmomanometer main body has reference pressure display means for displaying the reference pressure and detection pressure display means for displaying the detected pressure detected by the pressure detection means, and presses the wrist radial artery with a finger. The reference pressurizing force and the detected pressure are displayed simultaneously so that the reference pressurizing force can be followed.

  In addition, the sphygmomanometer body extracts the pulse rate and pulse wave amplitude from the volume pulse wave detected by the volume pulse wave detection means, determines whether it is within a predetermined value range, and reports the determination result with a buzzer It has the means.

  Further, the sphygmomanometer body is formed integrally with a ring provided with a light / pressure sensor unit.

  Further, the sphygmomanometer body is disposed in the wristwatch, and the light / pressure sensor unit is disposed in the wristwatch band.

  The light / pressure sensor unit includes transmission means for transmitting pressure waveform data and volume pulse waveform data, and the sphygmomanometer body includes reception means for receiving pressure waveform data and volume pulse waveform data. And

  Further, the blood pressure determination means averages the blood pressure values obtained by measuring in the pressure increasing process and the pressure decreasing process to determine the blood pressure.

  As described above, according to the present invention, the radial artery is directly pressurized, the volume vibration of the vascular wall of the pressurized site is directly detected optically, and the blood pressure is determined based on the volume vibration method. Anyone can measure blood pressure easily and accurately. In addition, it does not require a cuff / air pump and a large battery to drive it, it is about the size of a normal wristwatch, it can be worn at all times, and can be measured at any time, for example during exercise or bathing It has features such as

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optimal embodiment of the present invention will be described using the drawings. FIG. 1 shows an overall block diagram of an electronic blood pressure monitor according to the present invention. This electronic sphygmomanometer includes a light / pressure sensor unit 18 including a pressure detector 1 as a pressure detector and a volume pulse wave detector 2 as a pulse wave detector, an A / D converter 3, a liquid crystal display 4, and an MPU 5. A sphygmomanometer body 61 including a piezoelectric buzzer 6 and an operation unit 7.

FIG. 2 shows the structure of the light / pressure sensor unit 18. The light / pressure sensor unit 18 includes a base portion 13, a pressure sensor 11 as a pressure detecting means, a silicon gel 15, a light emitting diode 10 as a pulse wave detecting means, a photodiode 12 and a sheet 14. The pressure sensor 11 is a piezo bridge resistance type semiconductor sensor or a capacitance change detection type pressure sensor, and converts pressure into an electric signal. The light emitting diode 10 emits light in the near-infrared region having good biological permeability and absorption of hemoglobin. The emission wavelength is preferably about 800 to 900 nm. The photodiode 12 receives light that is incident on the living body from the light emitting diode 10 and is scattered and absorbed in the living body and reflected, and converts it into an electrical signal. The entire light / pressure sensor unit 18 is wrapped in a thin and strong sheet 14. The pressure receiving portion of the light / pressure sensor unit 18 is filled with a gel 15 made of silicon or urethane between the base portion 13 and the sheet 14, and the pressure sensor 11 is covered with the gel 15. When the pressure receiving portion of the light / pressure sensor unit 18 is in contact with the surface of the living body, the contact pressure (pressing force) is accurately transmitted to the pressure sensor 11 and can be detected. The base portion 13 of the light / pressure sensor unit 18 uses silicone rubber having appropriate elasticity. In order that the finger 30 senses the pulsation of the artery under the skin and detects the optimum position, it is preferable that the Young's modulus of the silicone rubber is 2 MPa or more and 100 MPa or less.

  Next, the measurement principle of the present invention will be described with reference to FIGS. FIG. 3 is a cross-sectional view of the wrist. The radial artery 21 is located on the radius 26. The radial artery 21 is usually the artery that is most easily recognized when examining the pulse rate and the like, and its position can be easily understood by touching it with a finger. The diameter of the radial artery depends on physique factors such as height, weight, and body surface area, but is generally 2.5-3.5 mm for Japanese men and 2.2-3.0 mm for women. The relationship between the pressure applied to the arterial tube (internal / external pressure difference) and the internal volume of the blood vessel has a shape that follows a generally known tube law. A volume pulse wave is a change in the internal volume of the blood vessel detected by optical means. According to the volume vibration method, the volume pulse wave has the maximum amplitude because the difference between the average blood pressure in the blood vessel and the external blood pressure is zero. The externally applied pressure at this time becomes the average blood pressure. Further, the externally applied pressure is increased, the blood vessel is blocked, the blood flow is stopped, and the externally applied pressure when the volume pulse wave disappears becomes the maximum blood pressure. In the volume vibration method, the artery is directly pressurized, the volume vibration of the pressurized blood vessel wall is optically detected directly, and the blood pressure is determined from the displacement behavior of the blood vessel, so that the accuracy of blood pressure measurement is improved.

  In the present invention, pressure is applied to the wrist radial artery 21 using the finger 30 shown in FIG. 4 via the light / pressure sensor unit 18. As described above, since the light / pressure sensor unit 18 has the base member 13 as an elastic member, the finger 30 can sufficiently sense the pulse wave of the wrist radial artery 21 even through the light / pressure sensor unit 18. . As a result, the measurement position of the artery is optimized by fully utilizing human senses and sensibilities, and the accuracy of the volume vibration method as a blood pressure determination means is taken into account, and the method according to the present invention is used. The accuracy of the blood pressure determination method is guaranteed.

  The detection of the externally applied pressure and the volume pulse wave is performed using a light / pressure sensor unit 18 comprising a pressure sensor 11, a light emitting diode 10 and a photodiode 12 as shown in FIG.

  The subject pushes his radial artery 21 with his / her finger 30 uniformly and slowly over a period of about 20 seconds. When the finger 30 can no longer feel the pulsation of the radial artery 21, the pressure is reduced over about 20 seconds. By doing in this way, the volume pulse wave waveform 51 and the externally applied pressure waveform 50 corresponding to it are obtained as shown in FIG.

  Since the pressure waveform of the radial artery 21 is superimposed on the externally applied pressure in the pressure waveform 50, a moving average process is performed to obtain the externally applied pressure. Waveform analysis is performed on the superimposed pressure pulse wave, and the applied pressure at which waveform clamping begins to occur at the lower part of the pressure pulse waveform is determined as the pressure corresponding to the minimum blood pressure, and is used as one piece of information for determining the minimum blood pressure. It can be used to improve the accuracy of blood pressure monitors.

The average blood pressure (Pa) is obtained from the externally applied pressure value at the time when the volume pulse wave shows the maximum amplitude. The maximum blood pressure (Pm) is obtained from the value of the externally applied pressure when the volume pulse wave substantially disappears. The blood pressure can be determined by either the pressurization process or the decompression process. Therefore, it is possible to perform highly accurate blood pressure determination by performing measurement in both the pressurization process and the decompression process and calculating the average value of both. The minimum blood pressure can be estimated from the maximum blood pressure (Pm) and the average blood pressure (Pa) using the fact that the volume pulse waveform and the pressure pulse waveform are similar.

  The first embodiment of the present invention will be described below. FIG. 6 shows the appearance of the present invention. The light / pressure sensor unit 18 is disposed at a position corresponding to the finger pad of the ring 60. A ring 60 integrated with the sphygmomanometer body 61 is attached to the finger 30. A maximum blood pressure 62, a minimum blood pressure 63, and an average blood pressure 64 are displayed on the liquid crystal display 4. The button 68 is a switch for starting a blood pressure acquisition operation.

  In this embodiment, a method for measuring in the step-up process will be described. The subject slowly pushes the portion of the light / pressure sensor unit 18 in which the user's finger 30 places his radial artery 21 on the ring 60 over about 20 seconds. At this time, a suitable reference pressure is displayed on the liquid crystal display 4 of the sphygmomanometer main body 61 as a detected pressure display means by a circle 65 on the circumference that makes a round in 20 seconds, and the externally applied pressure detected by the pressure sensor 11 is displayed. The detected pressure is displayed by the needle 66, and the subject is informed that the needle 66 follows the circle 65. When the volume pulse wave intensity detected at this time is within the range of the appropriate signal intensity determined in advance, although not shown in the figure, for example, a short beep is emitted from the piezoelectric buzzer provided in the sphygmomanometer body 61, and the subject is measured. Informs that is done normally. When the pulse wave intensity is less than the appropriate signal intensity, for example, a long sound is emitted as an error signal, and remeasurement is instructed. When the value indicated by the pressure sensor 11 reaches a preset maximum pressurization value, the end of pressurization is issued, for example, with a different frequency to notify the end of measurement. The time-series data of the volume pulse waveform data and the applied pressure waveform data are sequentially A / D converted by the A / D converter 3 and recorded in the memory in the MPU 5. The sampling time interval of the A / D converter 3 is preferably about 10 ms.

  After the pressurization is completed, the maximum blood pressure and the average blood pressure are determined from the volume pulse waveform data and the pressure waveform data recorded in the memory in the MPU 5 according to a known volume vibration method. The minimum blood pressure can be estimated from the maximum blood pressure (Pm) and the average blood pressure (Pa) using the fact that the volume pulse waveform and the pressure pulse waveform are similar. The obtained maximum blood pressure, average blood pressure, and minimum blood pressure are displayed on the liquid crystal display 4.

  Light-emitting diodes are used to eliminate fluctuations such as AC commercial frequency noise from fluorescent lamps and the like mixed into the photodiode 12 as stray light, low-frequency noise derived from natural external light and respiration, and temperature-dependent drift. Is pulse driven at 1 kHz. Furthermore, S / N can be further improved by detecting only the signal component using a bandpass filter that selectively transmits the frequency.

  In this embodiment, the ring 60 and the sphygmomanometer body 61 are integrated, but it is also possible to connect the ring 60 and the sphygmomanometer body 61 wirelessly and transmit the waveform data acquired by the ring 60 to the sphygmomanometer body 61. It is. In this case, the sphygmomanometer body 61 is preferably a wristwatch type.

  In this method, since the radial artery is pressurized with your finger, the amount of pressing will vary slightly at first, but most people can measure blood pressure with sufficient accuracy just by practicing a few measurements. It has been confirmed.

The above explanation was a case where the subject measured his blood pressure himself, but when a nurse or caregiver measured the subject's blood pressure in a place such as a hospital or a nursing care, It is clear that the blood pressure measurement can be performed very easily. Moreover, since it is an ultra-small blood pressure monitor, the convenience of carrying is remarkably improved, and it is very useful for nurses and caregivers.

  FIG. 7 shows the appearance of a wristwatch when the present invention is applied to the wristwatch. The light / pressure sensor unit 18 is provided at a position corresponding to the radial artery 21 of the wristwatch band 70. A blood pressure monitor main body (not shown) is disposed inside the wristwatch. The entire wristband may be made of metal, but the portion where the light / pressure sensor unit 18 is provided is a cavity 75. Both ends of the light / pressure sensor unit 18 are held by sliders 71 and 72 so that the light / pressure sensor unit 18 can slide in the cavity 75. The base part 13 of the light / pressure sensor unit 18 is made of silicone rubber having a Young's modulus of 2 MPa or more and 100 MPa or less. is there. A maximum blood pressure 62, a minimum blood pressure 63, and an average blood pressure 64 are displayed on the liquid crystal display 4. The button 68 is a switch for starting a blood pressure acquisition operation.

  In this embodiment, a method for measuring in the step-up process will be described. The subject slowly pushes his radial artery 21 with his / her finger 30 with the light / pressure sensor unit 18 provided in the band 70 over about 20 seconds. At this time, on the liquid crystal display 4 of the wristwatch body, a suitable pressurizing amount is displayed by a circle 77 on the outer periphery that makes a round in 20 seconds, and the pressure value detected by the pressure sensor 11 is displayed by a diamond 78 that moves on the outer periphery. The subject is informed that the rhombus 78 follows the circle 77. At this time, when the volume pulse wave intensity detected by the photodiode 12 is within the range of a predetermined appropriate signal intensity, although not shown in the figure, for example, it emits a sound shorter than the piezoelectric buzzer provided in the sphygmomanometer body, Inform the subject that the measurement is normal. When the pulse wave intensity is less than the appropriate signal intensity, for example, a long sound is emitted as an error signal, and remeasurement is instructed. When the detected volume pulse wave becomes substantially zero, the external pressure at that time is determined as the maximum blood pressure, and for example, a different frequency is emitted, for example, to notify the end of measurement.

It is a block diagram which shows the Example of this invention. It is sectional drawing which shows the structure of the light and pressure sensor of this invention. It is sectional drawing which shows the position of the artery of a wrist. It is a figure explaining the measuring method of this invention. It is a figure which shows the volume pulse wave waveform and pressure waveform which are obtained by this invention. It is a figure which shows the 1st Example of this invention. It is a figure which shows the 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure detection part 2 Volume pulse wave detection part 3 A / D converter 4 Liquid crystal display 5 MPU
6 Piezoelectric buzzer 7 Operation part 10 Light emitting diode 11 Pressure sensor 12 Photodiode 13 Base part 14 Coating film 15 Gel 18 Light / pressure sensor unit 21 Radial artery 22 Skin 23 Tendon 24 Ulna artery 25 Ulna 26 Radius 27 Vein 30 Finger 31 Living body Tissue 50 Pressure waveform 51 Volume pulse waveform 60 Ring 61 Sphygmomanometer main body 62 Maximum blood pressure display 63 Minimum blood pressure display 64 Average blood pressure display 65 Circle 66 Needle 67 Button 68 Button 71, 72 Slider 75 Cavity 77 Circle 78 Diamond

Claims (9)

A caffres electronic sphygmomanometer comprising a pressure detecting unit in contact with a living body surface, a pulse wave detecting unit having a photoelectric sensor, and a blood pressure determining unit, and detecting a pulse wave of a wrist radial artery, a sphygmomanometer body, and a light / pressure sensor unit And a pressurizing unit that pressurizes the wrist radial artery with a finger via the light / pressure sensor unit, and the blood pressure determining unit uses a volume vibration method,
The optical and pressure sensor unit, and the base portion made of an elastic member, wherein the to Luke Furesu electronic sphygmomanometer further comprising a pressure detecting means and the pulse wave detecting means are embedded in the base body. 2. The caffres electronic sphygmomanometer according to claim 1, wherein the light / pressure sensor unit is provided on a ring. Base unit Kafuresu electronic sphygmomanometer according to claim 1 or claim 2, characterized in that the Young's modulus is made of 100MPa or less of the elastic member than 2MPa of the light-pressure sensor unit. The sphygmomanometer main body has a reference pressure display means for displaying a reference pressure, and a detection pressure display means for displaying a detected pressure detected by the pressure detection means, and pressurizes the wrist radial artery with a finger. wherein according to claims 1, and the reference pressure as the reference pressure can follow with the detected pressure, characterized in that it is configured to be displayed simultaneously in any one of claims 3 when Caffres electronic sphygmomanometer. The blood pressure monitor main body extracts the pulse rate and pulse wave amplitude from the volume pulse wave detected by the volume pulse wave detection unit, determines whether or not it is within a predetermined value range, and notifies the determination result with a buzzer The cuffless electronic sphygmomanometer according to any one of claims 1 to 4 , characterized by comprising: Kafuresu electronic sphygmomanometer according to any one of claims 1 5, characterized in that the sphygmomanometer body said light-pressure sensor unit is formed integrally with the ring provided. The sphygmomanometer body is disposed in a wristwatch, Kafuresu electrons according to claims 1, wherein the light-pressure sensor unit, characterized in that it is arranged in the band of the wrist watch in any one of claims 5 Sphygmomanometer. The light / pressure sensor unit includes transmission means for transmitting the pressure waveform data and the volume pulse waveform data, and the blood pressure monitor main body includes reception means for receiving the pressure waveform data and the volume pulse waveform data. The caffres electronic sphygmomanometer according to any one of claims 1 to 5 , wherein: Kafuresu according to any one of claims 1 to 8, wherein the blood pressure determining means determines a blood pressure by an average blood pressure value of both obtained by measuring at the pressure reduction process and the boosting process Electronic blood pressure monitor.

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