JPS6247337A - Electronic hemomanometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an improvement in means for detecting insufficient pressurization of fluid within a cuff in an electronic blood pressure monitor.

(B) Conventional technology Conventionally, as a means for detecting insufficient pressurization of fluid in the cuff of an electronic blood pressure monitor, especially an electronic blood pressure monitor that employs the vibration method, the magnitude of the pulse wave amplitude at the start of measurement has been set to a predetermined value. It is known that when the above conditions are met, the pressure is insufficient.

This principle will be explained below based on FIG.

FIG. 8 shows the relationship between the fluid pressure within the cuff (hereinafter referred to as cuff pressure) and the elapsed time of the measurement operation. When the cuff is wrapped around the upper arm of the person being measured and the cuff is pressurized, if the cuff pressure is sufficiently increased (point A in Figure 8), the subsequent cuff pressure is reduced by the decompression means at a constant tracing speed. As this progresses, a pulse wave WA occurs. This pulse wave WA is caused by the pulsation from the heart, which is applied to the blood in an attempt to cause blood to flow into the artery where the blood flow has been stopped by the tightening force of the cuff, and is transmitted to the fluid inside the cuff, reducing the cuff pressure. As the amplitude increases, it gradually occurs, reaches a maximum amplitude at a certain point, and then gradually decreases until it becomes undetectable. If the cuff pressure is initially sufficiently increased, decompression is started with a constant slow liquid and the measurement is started (A
At point ), the amplitude of the pulse wave W is extremely small.

However, if the cuff pressure is not sufficiently increased at the beginning (point B), the cuff's tightening force on the upper arm, etc. is small, and the artery is not completely stopped, so the pulse wave WB is already high when the measurement starts. The initial amplitude P of the pulse wave W is also large. Therefore, if the pulse wave amplitude at the start of measurement is larger than a certain reference value, it can be determined that the cuff pressurization is insufficient.

(c) Problems to be solved by the invention However, with this invention, the standard value for determining whether or not pressurization is insufficient is fixed, so when the pulse wave amplitude is large, such as in a hypertensive patient, However, even though the cuff is actually sufficiently pressurized, there is a risk that the insufficient pressurization detection means will operate, causing unnecessary pressurization and increasing the patient's pain. Furthermore, in cases where the pulse wave amplitude is small, such as in a person with hypotension, even if the cuff is actually insufficiently pressurized, the insufficient pressurization detection means may not operate and accurate blood pressure measurement may not be possible. .

The present invention was made in view of the above-mentioned disadvantages, and an object of the present invention is to provide an electronic blood pressure monitor that accurately detects insufficient pressurization.

(d) Means for Solving the Problems As shown in FIG. Alternatively, a pressure reducing means 3 that rapidly reduces the pressure, a pressure sensor 4 that detects fluid pressure within the cuff, a pulse wave component detecting means 5 that detects a pulse wave component included in the output signal of this pressure sensor, and a pulse wave component detecting means 5 that detects a pulse wave component included in the output signal of the pressure sensor The apparatus includes a pulse wave amplitude calculation means 6 for calculating the amplitude of a wave component, and a quantitative means 7 for quantifying a blood pressure value based on the calculated pulse wave amplitude and the output signal of the pressure sensor, wherein the pulse wave amplitude calculation means a pressure insufficiency detection means 8 which compares the pulse wave amplitude value initially obtained by the means with a reference value, and determines that the inside of the cuff is insufficiently pressurized if the pulse wave amplitude value is larger; and a reference value control means 9 for controlling the reference value according to the output value of j.

(E) Function In this electronic blood pressure monitor, at the start of measurement, the cuff pressure Q is detected by the pressure sensor, and the pulse wave amplitude P is calculated by the pulse wave amplitude calculation means. Then, the reference value control means detects the detected cuff pressure Q.
Based on this, a reference value T is determined. Next, the reference value T is determined by the insufficient pressurization detection means.

The pulse wave amplitude P is compared with the pulse wave amplitude P, and if the pulse wave amplitude P is large, it is determined that pressurization is insufficient.

When the cuff pressure Q is large, the reference value TH is also increased accordingly.
When the cuff pressure Q is small, the reference value TH is also made small accordingly. Therefore, even if the pulse wave amplitude value is the same, if the cuff pressure Q is small, it is not determined that there is insufficient pressurization, but if the cuff pressure Q is large, the base value ζ value T.

may be larger than the pulse wave amplitude value P, and it may be determined that pressurization is insufficient.

Next, the principle of employing this invention will be explained with reference to FIG.

Figure 2 shows data on systolic blood pressure and pulse pressure (difference between systolic and diastolic blood pressure) collected by the inventor of the present application, with the horizontal axis representing the systolic blood pressure (mml1g) and the vertical axis representing the pulse pressure. Value (mmHg
) is plotted as According to this figure, a certain correlation is recognized between the systolic blood pressure value and the pulse pressure value. The L line in FIG. 2 is drawn to approximate the systolic blood pressure value and the pulse pressure value in a linear relationship.

On the other hand, it is known that the pulse pressure value is in a proportional relationship with the pulse wave amplitude value, and when the systolic blood pressure value is large, the pulse wave amplitude value P also increases between the systolic blood pressure value and the pulse wave amplitude value. There is a large correlation (this is because the arterial wall pulsates due to pulse pressure, and the pulse wave is what is transmitted through the muscles and skin to the cuff).

Therefore, if we judge whether or not the pressure is insufficient based on the threshold TII, which increases in proportion to the pressure value Q when the cuff is pressurized,
For hypertensive patients with large pulse wave amplitude P, the threshold Tl
Since l is large, it will not be mistakenly determined that there is insufficient pressurization. Conversely, for hypotensive patients with small pulse wave amplitude P,
The threshold value TH becomes small, and insufficient pressurization can be accurately detected.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 3 to 7.

FIG. 3 is an external perspective view of the electronic blood pressure monitor according to the embodiment, and 11
is the main body of the blood pressure monitor, which has a built-in measurement circuit, etc. A display 21 made of a liquid crystal element, a power switch 22, and a pressure switch 23 are provided on the top surface of the blood pressure monitor main body 11.

A cuff 12 is connected to the blood pressure monitor main body 11 via a flexible tube 24 made of a material such as rubber. The cuff 12 is shaped like an air stake when expanded, and is wrapped around the subject's upper body or the like.

FIG. 4 is a block diagram of the pneumatic system and measurement circuit of the electronic blood pressure monitor according to this embodiment. The pneumatic system includes the cuff 12,
Tube 24, piping 25 to which this tube 24 is connected
a, 25b, 25c and these piping 25a, 25b, 2
Exhaust valve 15 as a pressure reducing means, pressure pump I3 as a pressurizing means, and pressure sensor 1 provided at each end of 5C
Consists of 4. The exhaust valve 15 can exhaust the air in the cafe 2 at a constant slow speed or at a rapid rate, and together with the pressurizing pump 13, it is connected to a microcomputer (MP), which will be described later.
The operation is controlled by U) 20.

As the pressure sensor 14, an appropriate device such as a diaphragm pressure transducer using a strain gauge or a semiconductor pressure transducer element can be adopted.

The measurement circuit includes an amplifier 18 that amplifies the output signal of the pressure sensor 14, a bandpass filter 16 as a pulse wave component detection means that detects a pulse wave component from the output signal of the amplifier I8, and an output signal of the amplifier 18 and the bandpass filter 16. It consists of an A/D converter 19 for converting into digital signals and a microcomputer 20. The microcomputer 20 includes a pressurization insufficient detection means and a quantification means for quantifying the blood pressure value based on the vibration method, and also controls the exhaust valve 15 and the pressurization pump 13 to determine the blood pressure value obtained by measurement. It is displayed on the display 21. In addition, the microcomputer 20 has
A power switch 22 and a pressure switch 23 are connected.

Next, the operation of this embodiment of the electronic blood pressure monitor will be explained in FIGS. 5 and 6.
This will be explained below based on the figures.

First, as a measurement preparation step, the power switch 22 is turned on and the cuff 12 is wrapped and fixed around the upper arm of the person to be measured. The microcomputer 20 determines whether the pressure switch 23 is on (step 5TI), and if it is not on, repeats step STI.

When the pressurization switch 23 is turned on, the exhaust valve 15 is closed (step 5T2), and the pressurization pump 13 starts driving (step 5T3). In the next step ST4, it is determined whether the pressure switch 23 has been turned off, and if it has not been turned off, this step ST4 is repeated.

When the measurer determines that the cuff 12 is sufficiently pressurized, the measurer turns off the pressurization switch 23.

When the pressurization switch 23 is turned off, the process proceeds from step ST4 to step ST5, where insufficient pressurization is detected.

Details of the detection of insufficient pressurization will be described later.

In the next step ST6, slow exhaustion by the exhaust valve 15 is started, and in step ST7, blood pressure measurement processing is performed.

The blood pressure values (systolic blood pressure value, diastolic blood pressure value, etc.) obtained in step ST7 are displayed on the display 21 (step 5T8).
Then, the exhaust valve 15 rapidly exhausts the air remaining in the cafe 2 (step 5T9), and the measurement operation ends.

Next, the insufficient pressurization detection means will be explained with reference to FIG.
mml1g) is read from the A/D converter 19 (step 5T52). In the next step 5T53, the threshold value Tl
l is calculated from the cuff pressure value Q based on the following formula.

T11 = 0.0020+2.2...
- (1) The constants 0.002 and 2.2 in equation (1) were determined experimentally.

In addition, as an example of a more convenient means of calculating the threshold values T and l, in the case of Q≧200 (mml1g), T11
=2.6 (mml1g), Q<200 (mml1
In the case of g), Tit can also be set to 2.4 (mmHg).

In the next step 5T54, the microcomputer 20
reads the pulse wave amplitude value P from the A/D converter 19 and compares it with the threshold value T0.
If P>Tl+, it is determined that the pressurization is sufficient and the process returns to step ST6. If P>Tl+, the pressurization is determined to be insufficient and the process proceeds to the next step 5T5G. In step STS 6, the cuff pressure value Q is set to 30 (mml1g
) is set as the re-pressurizing target value, and the driving of the pressurizing pump 13 is restarted (step 5T57).

On the other hand, the microcomputer 20
Read the digital signal of the cuff pressure value Q (step 5T).
58), step ST5 compared with the repressurization target value X.
9) If Q≧X, it is assumed that the re-pressurization target value has been achieved, and the process returns to step ST51, where it is again determined whether or not pressurization is insufficient. If Q<X, the process returns to step ST58 and repeats steps 5T58 and 5T59 until Q≧X.

In this embodiment, the blood pressure measurement process in step ST7 is performed based on the principle of the vibration method. The outline of the vibration method will be explained with reference to FIGS. 7 and 8. Only the amplitude of the pulse wave WA (which actually has a higher wave number) in FIG. 8 is extracted and plotted against the elapsed time. By connecting them with a curved line, a pulse wave amplitude curve as shown in FIG. 7 is obtained.

The pulse wave amplitude curve gradually increases from point E, sharply increases from point 8, reaches a maximum value at point M, and then rapidly decreases.
It gradually decreases from point D and reaches almost zero at point F. At this time, it is empirically known that the cuff pressure corresponding to 8 points corresponds to the systolic blood pressure value, and the cuff pressure corresponding to point D corresponds to the diastolic blood pressure value. The vibration method uses this fact to calculate blood pressure values.

In the blood pressure measurement process in step ST7, the pulse wave -
The pulse wave amplitude value is calculated for each period (one period) or for each certain time interval, and is sequentially stored along with the cuff pressure value at that point.
The aforementioned 8 points and point D are determined based on the stored data, and the cuff pressure values corresponding to the 8 points and point D are defined as the systolic blood pressure value and the diastolic blood pressure value, respectively.

Of course, the blood pressure measurement process uses the auscultation method (a method that detects the sound called Korotkoff's sound that occurs when blood tries to flow through the arteries, and uses the cuff pressure value at the time that sound occurs as the blood pressure value). You can also do it.

In this case, a microphone (not shown) is attached to the cuff 12, and recognition means (not shown) for recognizing Korotkoff sounds from its output signal is provided.

Further, in this embodiment, the pressurizing pump 13 and the exhaust valve 15 are controlled by the microcomputer 20.
Both or one of them can be done manually, and the design can be changed as appropriate. In particular, when the pressurizing pump 13 is a manual type such as a rubber bulb, a warning means is provided to notify the operator on the display 21 when insufficient pressurization is detected, and the operator is advised to reapply the pressure. Try to encourage them.

(G) Effects of the Invention The electronic blood pressure monitor of the present invention compares the pulse wave amplitude value obtained by the pulse wave amplitude calculation means with a reference value (threshold value) calculated from the cuff pressure, and Since it is equipped with a means for detecting insufficient pressurization, it is possible to accurately determine whether or not there is insufficient pressurization even in hypertensive or hypotensive patients, and it is possible to without causing unnecessary pain,
It also has the advantage of being able to accurately measure blood pressure values.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of the present invention, the second part is a diagram showing the correlation between systolic blood pressure values and pulse pressure values, and FIG. 3 is a diagram showing an electronic blood pressure monitor according to an embodiment of the present invention. 4 is a circuit block diagram of the electronic blood pressure monitor, FIG. 5 is a flow diagram explaining the operation of the electronic blood pressure monitor, and FIG. 6 is a means for detecting insufficient pressurization in the electronic blood pressure monitor. Fig. 7 is a flowchart explaining the operation of , Fig. 7 is a diagram showing the relationship between the pulse wave amplitude and the elapsed time during the measurement operation, and Fig. 8 is a diagram showing the relationship between the cuff pressure value and the elapsed time during the measurement operation. FIG. 1. cuff, 2: pressurizing means, 3: depressurizing means,
4: Pressure sensor, 5: Pulse wave component detection means, 6
: pulse wave amplitude calculation means, 7; quantitative means, 8: insufficient pressurization detection means, 9; reference value control means. Patent applicant Tateishi Electric Co., Ltd. Agent
Patent Attorney Shigeru Nakamura Fig. 1 Fig. 2 fi A fmh (X CrntnHg) Fig. 3 Fig. 4 Fig. 7 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Hoshosho (spontaneous) March 12, 1986

Claims (3)

[Claims] (1) A cuff, a pressurizing means for pressurizing the fluid in the cuff, a depressurizing means for slowly or rapidly decompressing the fluid in the cuff, a pressure sensor for detecting the fluid pressure in the cuff, and the output of this pressure sensor. A pulse wave component detection means for detecting a pulse wave component included in the signal, a pulse wave amplitude calculation means for calculating the amplitude of the detected pulse wave component, and the calculated pulse wave amplitude and the output signal of the pressure sensor. , an electronic sphygmomanometer equipped with a quantitative means for quantifying a blood pressure value, the pulse wave amplitude value initially obtained by the pulse wave amplitude calculating means is compared with a reference value, and if the pulse wave amplitude value is larger, the cuff is removed. 1. An electronic blood pressure monitor comprising: insufficient pressurization detection means for detecting insufficient pressurization; and reference value control means for controlling the reference value according to an initial output value of the pressure sensor. (2) The electronic blood pressure monitor according to claim 1, wherein the pressurizing means repressurizes based on the output of the insufficient pressurization detecting means. (3) The electronic blood pressure monitor according to claim 1 or 2, further comprising a warning means activated by the output of the insufficient pressurization detection means.