JPH078274B2 - Electronic blood pressure monitor for fingers - Google Patents

Description

TECHNICAL FIELD The present invention relates to a finger electronic blood pressure monitor, and more particularly to a means for preventing damage to a cuff due to a finger being pulled out of the cuff during blood pressure measurement. Is.

(B) Conventional technology In general, an electronic blood pressure monitor for fingers compresses the finger with a cuff for the finger,
The photoelectric pulse wave sensor attached to this finger cuff detects changes in the arterial volume by finger compression and the pressure inside the cuff (hereinafter referred to as the cuff pressure) is detected by the pressure sensor to reduce the cuff pressure. It is known that the blood pressure value is determined based on the pulse wave and the cuff pressure obtained in.

(C) Problems to be Solved by the Invention In the conventional electronic blood pressure monitor for a finger described above, if the measurement is interrupted during blood pressure measurement and the user wants to remove the finger from the cuff, the clear switch is turned on to quickly increase the cuff pressure. It is configured to reduce the pressure.

However, there are cases where the person to be measured forcibly pulls his / her finger out of the cuff in the pressurized state during measurement (hereinafter referred to as “pullout”) without turning on the clear switch because of sudden work. In this case, the restriction due to the presence of a finger on the cuff is released, and the cuff expands to a volume equal to or larger than that in a normal use state (hereinafter referred to as overexpansion). With the currently used cuff material (rubber, etc.), if the above-mentioned over-expansion was repeated several times, the cuff would crack, causing air leakage, and the electronic blood pressure monitor for fingers could not be used. . In particular, this inconvenience was remarkable in the electronic blood pressure monitor for home use.

In addition, in order to prevent damage to the cuff due to the above-mentioned inflation,
If the film thickness of the rubber film forming the cuff is large, the cuff pressure is not correctly transmitted to the finger, which causes a problem that accurate blood pressure measurement is difficult.

The present invention has been made in view of the above inconvenience, and an object thereof is to provide an electronic blood pressure monitor for a finger that can prevent the cuff from being destroyed while maintaining the accuracy of blood pressure measurement.

(D) Means for Solving the Problems The electronic blood pressure monitor for a finger of the present invention has a cuff 1 for pressing a finger and a cuff 1 up to a predetermined set value as shown in the schematic configuration of FIG. Pressurizing means 2 for pressing, depressurizing means 3 for depressurizing the pressure of the cuff 1, a pressure sensor 4 for detecting the pressure of the cuff 1, and a pulse wave attached to the cuff 1 for detecting a pulse wave from the finger. A pulse wave sensor comprising: a sensor 5; and a blood pressure determining means 6 for measuring blood pressure based on the pulse wave detected by the pulse wave sensor 5 and the pressure of the cuff 1 detected by the pressure sensor 4. Characteristically, there is provided finger withdrawal detection means 7 for detecting the withdrawal of the finger from the cuff 1 based on the baseline fluctuation of the pulse wave from 5.

(E) Operation The operation of the electronic blood pressure monitor for a finger of the present invention will be described below with reference to FIGS. 5 (a) and 5 (b).

FIG. 5 (a) shows a pulse wave detected by the pulse wave sensor 5 in the process of pressurizing the cuff 1 to a pressure higher than the systolic blood pressure of the subject, pressing the finger, and then depressurizing the depressurizing means 3 at a constant slow speed. Shows the temporal transition of. FIG. 5 (a) shows a normal state in which there is no finger withdrawal during blood pressure measurement, the baseline B is stable at a substantially constant level, and the pulse wave is periodically generated on the baseline B. appear.

On the other hand, FIG. 5 (b) shows the pulse wave when the finger is pulled out by the cuff 1 during the measurement. The level of the baseline B greatly changes due to the finger withdrawal, and the finger withdrawal detection means 7 detects this variation of the baseline B by setting a threshold value and comparing it with the level of the pulse wave, In response to the detection of the finger withdrawal, the decompression means 3 can take appropriate cuff damage prevention means such as rapidly decompressing the cuff 1.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 2 to 4 and 5 (b).

FIG. 2 is an external perspective view of a finger electronic sphygmomanometer in which the present invention is implemented. The finger electronic sphygmomanometer is composed of a main body 11 and a cuff housing portion 12, which are connected by a cord wire 13. Has been done.

On the case surface of the main body 11, a display device 14 for displaying the maximum blood pressure, the minimum blood pressure, the pulse rate, etc., a pressurizing value setting device 15 for selecting a pressurizing set value, a clear key 16, a start key 17, a power key 18 are provided.

A cuff rubber bag 19 having a cylindrical outer shape is stored in the case of the cuff storage portion 12. Although not shown, the cuff rubber bag 19 is provided with a pulse wave sensor for detecting a finger pulse wave, and an electric signal line connecting the pulse wave sensor and the main body 11 and the cuff rubber bag 19 and the main body 11 are provided. The rubber pipes connecting the two are bundled together and connected as a cord wire 13 between them.

FIG. 3 shows a circuit block diagram of the electronic blood pressure monitor for the finger. In the figure, pressurization value setting switch 15a, clear switch 16a, start switch 17a and power switch
18a respectively correspond to the pressurization value setting device 15, the clear key 16, the start key 17, and the power key 18, and are turned on when these keys are operated. The on / off signals and setting signals of these switches are input to the CPU 20.

The motor drive circuit 21 is adapted to turn on / off a motor (pressurizing means) 22 of a pressurizing pump in response to a command from the CPU 20. The cuff rubber bag 19 is pressurized by the start of the motor 22.

The quick exhaust valve drive circuit 23 is configured to open / close the valve (pressure reducing means) 24 in response to a command from the CPU 20.

By driving the motor 22, air pressure is supplied to the cuff rubber bag 19 via the air tank 25, and the pressure of the cuff rubber bag 19 is converted into an electric signal by the semiconductor pressure sensor 26 and passed through the amplifier circuit 27 to the A / D converter. Converted to digital signal at 28, CPU
It is designed to be incorporated into 20.

Furthermore, the LED drive circuit 29 drives the light emitting element 30 attached to the cuff rubber bag 19 in response to a command from the CPU 20, while the signal received by the light receiving element 31 is passed through the filter 32 and the amplifier circuit 33. , A / D converter 28 performs digital conversion and is also taken in by the CPU 20. The light emitting element 30 and the light receiving element 31 constitute a pulse wave sensor.

Display data from the CPU 20 is displayed on the display (LCD) 14 via the LED drive circuit 34. Further, in order to notify an error or the like, a buzzer 36 is driven via a buzzer drive circuit 35 by a command from the CPU 20. Reference numeral 37 is a slow speed exhaust valve (pressure reducing means).

The CPU 20 executes various functions according to the program of the flowchart described later, and the above-mentioned constituent circuits execute the blood pressure measurement operation under the control of the CPU 20.

Next, the operation of the electronic blood pressure monitor for a finger according to this embodiment will be described in a fourth step.
The description will be made below mainly with reference to FIG. 5 and FIG.

First, when the measurer presses the power key 18 and turns on the power switch 18a, input / output and display initialization processing (initialization) of the LCD 14 is performed [step (hereinafter referred to as ST)].
1]. Then, it waits in ST2 until the start switch 17a is turned on.

Next, the operator operates the pressurization value setting device 15 to select a setting value suitable for himself, for example, insert the index finger of the left hand into the cuff rubber bag 19, and turn on the start switch 17a, and from ST2 to ST3. Then, the CPU 20 gives a command to the motor drive circuit 21, the motor 22 is driven, the cuff rubber bag 19 is pressurized to the value set by the pressurization value setter 15, and the finger is pressed.

When the cuff rubber bag 19 is pressurized to the set value in ST3, the CPU 20 stops the motor 22 and starts the fine speed exhaust from the slow speed exhaust valve 37 (ST4).

In ST5, the CPU 20 takes in the pulse wave level xi detected and amplified by the light receiving element 31 from the A / D converter 28 and samples it. In ST6, the pulse wave level xi sampled in ST5 is
The maximum blood pressure, average blood pressure, minimum blood pressure, etc. are determined based on There are various algorithms for calculating the maximum blood pressure, the average blood pressure, and the minimum blood pressure. For example, the systolic blood pressure is the cuff pressure when the pulse wave amplitude of the pulse wave calculated from the sampled pulse wave level xi data string exceeds a predetermined level, and the cuff pressure at the maximum pulse wave amplitude is averaged. Blood pressure is calculated from these maximum blood pressure and average blood pressure (3 x average blood pressure-
The maximum blood pressure) / 2 determines the minimum blood pressure. However, since the present invention does not mainly include the blood pressure determination process, detailed description thereof will be omitted.

In the next ST7, it is determined whether the maximum blood pressure, the average blood pressure, the minimum blood pressure, etc. have been determined in the blood pressure determination process (ST6). If the blood pressure has been determined, proceed to ST8, if the blood pressure has not been determined. Goes to ST10.

In ST10, the latest pulse wave level x sampled in ST5 x
It is determined whether i is larger than the upper limit threshold Th ₁ . The upper limit threshold value Th ₁ is set to be equal to or higher than the maximum value of the normal pulse wave level as shown in FIG. 5B for the pulse wave, and the pulse wave level xi exceeds the upper limit threshold value Th ₁ . If it is, it can be determined that there is a level fluctuation of the base line B ′ and there is a finger pull P. Therefore, if xi> Th _1, it is determined that the finger has been removed, and the process proceeds to ST12.

On the other hand, if it is determined in ST10 that xi ≦ Th ₁ , the process proceeds to ST11, and the pulse wave level xi is compared with the lower threshold Th ₂ . The lower limit threshold value Th ₂ is set to be equal to or lower than the maximum value of the normal pulse wave level as shown in FIG.
If the level of the pulse wave base line B ′ changes and xi ≦ Th ₂ , it can be determined that the finger has been withdrawn. Therefore, if xi> Th _2, it is determined that the finger movement is not detected, and the process returns to ST5 to continue the sampling of the pulse wave level xi and the blood pressure determination process (ST6). Xi ≦ T
If it is h _2, it is determined that the finger has been withdrawn, and the process proceeds to ST12.

In ST12, the CPU 20 gives a command to the LCD drive circuit 34, and the LCD 14
To display an error. At the same time, the buzzer 36 is also sounded to notify the operator of the fact that an error has occurred. Next, in ST9, the CPU 20 gives a command to the quick exhaust valve drive circuit 23, opens the valve 24, depressurizes the cuff rubber bag 19,
Stop blood pressure measurement.

If there is no finger pullout during blood pressure measurement, ST5, ST6, ST
7, ST10, ST11 are repeated to determine the maximum blood pressure, average blood pressure, minimum blood pressure, etc. When it is determined in ST7 that these blood pressures are determined, the process proceeds to ST8, and the obtained measurement results of the maximum blood pressure, the minimum blood pressure, etc. are displayed on the LCD 14. Then the S
Proceed to T9, perform rapid evacuation, depressurize the cuff rubber bag 19, and finish the measurement.

It should be noted that in the above embodiment, the degree of fluctuation of the baseline level of the pulse wave is determined by using two threshold values, the upper threshold value Th ₁ and the lower threshold value Th ₂ , so that the movement of the finger is detected. However, only one of the upper limit and the lower limit threshold may be set, and can be appropriately changed.

Further, in the above-described embodiment, the finger withdrawal detection is performed while the cuff is being slowly exhausted (during blood pressure determination processing).
Even during the process of pressurizing the cuff, this finger withdrawal detection can be performed as soon as the baseline level of the pulse wave is stable, and can be changed appropriately.

(G) Effect of the Invention The electronic sphygmomanometer for fingers of the present invention is characterized by a finger withdrawal detection means for detecting the withdrawal of the finger from the cuff based on the fluctuation of the baseline of the pulse wave from the pulse wave sensor. In preparation for
When a finger is pulled out from the cuff during blood pressure measurement, there is an advantage that damage to the cuff can be prevented by taking appropriate countermeasures such as rapid depressurization of the cuff and operation of a notification means such as a buzzer.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of the present invention, and FIG. 2 is an external perspective view of an electronic blood pressure monitor for a finger according to an embodiment of the present invention.
FIG. 3 is a circuit block diagram of the electronic blood pressure monitor for the same finger, FIG. 4 is a diagram for explaining the operation of the electronic blood pressure monitor for the same finger, and FIGS. 5 (a) and 5 (b) are It is a figure explaining operation of an invention. 1: cuff, 2: pressurizing means, 3: depressurizing means, 4: pressure sensor, 5: pulse wave sensor, 6: blood pressure determining means, 7: finger withdrawal detecting means.

Claims (2)

[Claims] 1. A cuff for pressing a finger, a pressurizing means for pressurizing the cuff to a predetermined set value, a pressure reducing means for reducing the pressure of the cuff, and a pressure for detecting the pressure of the cuff. A sensor, a pulse wave sensor attached to the cuff for detecting a pulse wave from the finger, and a blood pressure determination based on the pulse wave detected by the pulse wave sensor and the pressure of the cuff detected by the pressure sensor. In a finger electronic blood pressure monitor including a blood pressure determining means for performing, a finger withdrawal detection means for detecting withdrawal of a finger from the cuff based on a variation of a baseline of a pulse wave from the pulse wave sensor is provided. Characteristic electronic blood pressure monitor for fingers. 2. The electronic blood pressure monitor for a finger according to claim 1, wherein said decompression means responds to said finger withdrawal detection means to rapidly reduce the pressure of said cuff.