JPH0779802B2 - Electronic blood pressure monitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronic sphygmomanometer.

(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 by the pulse wave and the cuff pressure obtained in.

As shown in FIG. 5 (a), the pulse wave is gradually generated as the cuff pressure is reduced, takes a maximum amplitude value, and then attenuates. To determine the systolic blood pressure, average blood pressure, and diastolic blood pressure from the pulse wave and the cuff pressure, for example, the cuff pressure corresponding to the start of the pulse wave [point S in FIG. Of the pulse waves, the one with the maximum upward peak (or the maximum amplitude) [M point in Fig. 5 (a)] is the cuff pressure at the time of delivery, and the minimum blood pressure is calculated from these maximum blood pressure and average blood pressure (3 × Mean blood pressure-maximum blood pressure) / 2. The upward peak refers to the maximum value of the pulse wave level in one cycle of the pulse wave.

(C) Problems to be Solved by the Invention In the above-mentioned conventional electronic blood pressure monitor for a finger, the minimum blood pressure is calculated from the maximum blood pressure and the average blood pressure. When a measurement error occurs in at least one of the systolic blood pressure and the average blood pressure due to a disturbance such as the disturbance of the pulse wave caused by moving the blood pressure, there is a disadvantage in that the diastolic blood pressure also has an error.

Further, depending on the person to be measured, as shown in FIG. 5 (b), the largest upward peak of the pulse wave does not clearly appear, and the mean blood pressure is erroneously determined. As a result, this erroneous mean There is an inconvenience that an error occurs in the minimum blood pressure calculated using blood pressure.

This invention has been made in view of the above inconvenience, and even when it is difficult to specify the maximum upward peak in the pulse wave of the person to be measured or disturbance such as an artifact, an electronic blood pressure capable of accurate blood pressure measurement The purpose is to provide a total.

(D) Means for Solving Problems As shown in the schematic configuration of FIG. 1, the electronic sphygmomanometer of the present invention has a pulse wave obtained from the living body when the cuff 1 is decompressed and the pressure of the cuff 1 by the pressure sensor 4. And a pulse wave downward peak detecting unit 7 for detecting a downward peak of the pulse wave. The blood pressure determining unit 6 includes the pulse pressure determining unit 6 for detecting the downward peak of the pulse wave. The wave downward peak detecting means 7 is configured to determine the pressure value at or near a time point at which the downward peak value of the pulse wave is detected as a minimum blood pressure around a predetermined time.

(E) Operation The operation of the electronic sphygmomanometer of the present invention will be described with reference to FIGS.
This will be described below with reference to FIG.

Depending on the person to be measured, the appearance of the maximum upward peak of the pulse wave may be unclear as described above, but even in that case, the minimum of the downward peak of each pulse wave Things appear clearly and it is easy to identify them (5th
(Xmin point in figure (b)). Here, the downward peak means the minimum value in one cycle of the pulse wave.

On the other hand, from the data collected by the inventor of the present application, it is recognized that there is a certain temporal relationship between the time when the maximum downward peak appears and the time when the cuff pressure becomes equal to the minimum blood pressure. Therefore, if the cuff pressure at the same time as the maximum downward peak detection or around a predetermined time around the peak detection time (with little error) is the minimum blood pressure, the minimum blood pressure is determined regardless of whether the maximum blood pressure and the average blood pressure are determined. Blood pressure can be accurately determined.

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

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 14 for displaying the maximum blood pressure, the minimum blood pressure, etc., a pressurization value setting device 15 for selecting a pressurization set value, a clear key 16, a start key 17, and a power key 18 are provided. Has been.

A cuff rubber bag 19 having a cylindrical outer shape is stored in the case of the cuff storage portion 12. Although not shown in the figure, 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 tubes connecting the two are bundled 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 LCD drive circuit 34. Further, in order to notify an error or the like, the buzzer 36 is driven via the 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.
A description will be given below with reference to the drawings.

First, when the power key 18 is pressed and the power switch 18a is turned on, the input / output and the display on the LCD 14 are initialized (initialization) [step (hereinafter referred to as ST) 1], and the start switch 17a is turned on. Until ST2.

Next, the person to be measured inserts the index finger of the left hand into the cuff rubber bag 19, and the start key 17 is pressed to start the switch.
When 17a is turned on, the process proceeds from ST2 to ST3, the CPU 20 gives a command to the motor drive circuit 21, drives the motor 22, pressurizes the cuff rubber bag 19 up to the set value selected by the pressurization setting switch 15a, and measures. Squeezes the person's finger.

When the cuff rubber bag 19 is pressurized to the set value, the CPU 20 stops the motor 22 and starts the fine speed exhaust from the slow speed exhaust valve 37 (ST4). Although not shown in FIG. 4, the CPU 20 thereafter sets the light receiving element 31 at a predetermined sampling cycle.
The pulse wave level detected by is taken in from the A / D converter 28.

Next, in ST5, the appearance of the first pulse wave is detected based on the sampled pulse wave level data, and the cuff pressure at this time is set as the systolic blood pressure (SYS) and stored.

In ST6, first, the pulse wave counter C that counts the number of pulse waves, the minimum xmin of the pulse wave downward peak values, and the downward peak value x _m of each pulse wave are set to zero. The CPU 20 detects one cycle of each pulse wave based on the sampled pulse wave level fetched from the A / D converter 28 and calculates the downward peak value x _m . During this period, the process stands by at ST7, one cycle of the pulse wave is detected, and if the downward peak value x _m is obtained, the process proceeds to ST8.

In ST8, compares the downward peak value x _m downward peak value obtained so far x _1, x _2, ......, and x _min the minimum value of the x _m-1 is substituted, x _{If m} is less than or equal to x _min , the pulse wave downward peak value continues to decrease, and the process proceeds to ST14, where the CPU 20 sets the pulse wave counter C to zero (reset),
The current cuff pressure P is taken in from the A / D converter 28 and used as a temporary minimum blood pressure D. Then proceed to ST15, and the minimum downward peak value x
After updating _min to the current downward peak value x _m , the process returns to ST7 to prepare for the next pulse wave detection.

On the other hand, in ST8, when x _m is determined to be larger than x _min (x _m > x _min ), the minimum downward peak value is already obtained,
The pulse wave counter C is incremented by 1 (ST9). Next, in ST10, it is determined whether or not the pulse wave counter C is equal to 3, and if they are equal, the process returns to ST11, and if they are not equal, returns to ST7 to prepare for the next pulse wave detection. As described above, when the above determination is performed for the pulse wave counter C, the temporal transition of the downward pulse value of the pulse wave is not necessarily smooth and there is some variation.
For the time being, after the pulse wave downward peak value that seems to be the minimum is obtained,
A pulse wave downward peak value larger than this pulse wave downward peak value is 3
This is to prevent the blood pressure measurement error due to the variation in the downward peak value by determining that the downward peak value of the minimum pulse wave is the true minimum value if continuously obtained.

In ST11, the provisional diastolic blood pressure D obtained in ST14 is used as diastolic blood pressure.
DIA, and in ST12 this DIA and SYS obtained in ST5 above
Displayed on LCD14, at the last ST13, CPU20 gives a command to quick exhaust valve drive circuit 23, opens valve 24, cuff rubber bag
The air inside 19 is rapidly exhausted, and the blood pressure measurement is completed.

Here, the measurement data by the electronic sphygmomanometer of the present invention is shown in FIG. The measurement method is one in which one person simultaneously measures with an arm and a finger and two times per person, and the result is plotted as ◯. The upper arm auscultation method was used for the arm measurement, and the electronic blood pressure monitor of the present invention was used for the finger measurement. In FIG. 6, N represents the number of samples, and R represents the correlation coefficient by the least square method. According to the measurement data shown in FIG. 6, the correlation coefficient of the measurement result is R = 0.906, which shows that there is a high correlation with the upper arm auscultation method, and the time point at which the downward peak value is detected or a predetermined time near it It is understood that the pressure value before and after may be determined as the diastolic blood pressure.

In the above embodiment, the cuff pressure at the time when the minimum pulse wave downward peak value is obtained is the minimum blood pressure, but the invention is not limited to this, and for example, at the time of detecting the minimum pulse wave downward peak value. The cuff pressure with little error before or after a predetermined time may be set as the minimum blood pressure, or the like, and may be appropriately changed to meet the use condition.

(G) Effect of the Invention The electronic sphygmomanometer of the present invention has pulse wave downward peak detecting means for detecting the downward peak of the pulse wave, and the blood pressure determining means is
Since the pulse wave downward peak detection means determines the pressure value around the time when the downward peak value of the pulse wave is detected or around the predetermined time as the diastolic blood pressure, the error caused by the disturbance such as an artifact or the This has an advantage that the blood pressure determination error caused by the difficulty in identifying the pulse wave of the measurer having the maximum upward peak value (or maximum amplitude value) can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the outline of the configuration of the present invention, FIG. 2 is an external perspective view of an electronic blood pressure monitor for a finger according to an embodiment of the present invention, and FIG. 3 is an electronic blood pressure monitor for the same finger. Circuit block diagram of
FIG. 4 is a flow chart for explaining the operation of the electronic blood pressure monitor for the finger, and FIGS. 5 (a) and 5 (b) are pulse diagrams for explaining the problems of the prior art and the operation of the present invention. FIG. 6 is a diagram showing a time transition of a wave, and FIG. 6 is a diagram showing measurement data by the electronic sphygmomanometer of the present invention. 1: cuff, 2: pressurizing means, 3: depressurizing means, 4: pressure sensor, 5: pulse wave sensor, 6: blood pressure determining means, 7: pulse wave downward peak detecting means.

Claims (1)

[Claims] 1. An electronic sphygmomanometer equipped with blood pressure determining means for determining blood pressure using a pulse wave obtained from a living body and a pressure value of the cuff obtained by a pressure sensor when decompressing the cuff, wherein a downward peak of the pulse wave. The pulse wave downward peak detecting means for detecting, the blood pressure determining means, the pressure value before and after a predetermined time at or near the time when the pulse wave downward peak detecting means detects the downward peak value of the pulse wave. An electronic sphygmomanometer characterized in that is determined as the minimum blood pressure.