JPH0369531B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a blood pressure measuring device, and more specifically, the present invention relates to a blood pressure measuring device, and more specifically, in blood pressure measurement, air is supplied into a cuff to raise the pressure to a certain height, and then at a certain speed. This invention relates to an improvement in a device that measures blood pressure while exhausting the air.

[Conventional technology]

Traditionally, blood pressure monitors measure the maximum and minimum blood pressure that appears in the arteries due to the pumping action of the heart's contraction and expansion movements, and a blood pressure monitor that has been commonly used for a long time is shown in Figure 6. There is something like that.

In the figure, 1 is the case of the blood pressure monitor, and this case 1
A mounting base 2 that can be folded and stored is provided inside the mounting base 2, and a glass tube 4 that forms a mercury column 3 by vacuum-sealing mercury is attached to the mounting base 2, and a cage 5 that displays the height of the mercury column 3. is engraved.

There is a mercury tank 6 at the bottom of the mercury column 3,
A cuff 8 to be worn on the upper arm (not shown) is attached to the mercury tank 6 via a hollow rubber tube 9, and a manual rubber pump 10 is connected to the cuff 8 via a hollow rubber tube 7. installed.

This rubber pump 10 is provided with an exhaust port 11 and an exhaust adjustment valve 12.

A stethoscope 13 for listening to blood pressure sounds is constructed by connecting a microphone 14 and a receiver 15 with a hollow rubber tube 16.

To measure blood pressure with this blood pressure monitor, first wrap the cuff 8 around your upper arm, attach the receivers 15 of the stethoscope 13 to both ears, and place the microphone 14 between the upper arm and the upper arm 8 wrapped around the upper arm. , is attached near the artery, and the rubber pump 10 at hand is manually operated to send air into the cuff 8 through the rubber tube 7.

The air sent into the cuff 8 exerts pressure on the mercury tank 6 through the rubber tube 9, changing the height of the mercury column 3 in mmHg. At this time, the height of the mercury represents the amount of air pressure inside the cuff 8.

The height of this mercury column 3 is determined in advance using the rubber pump at hand, for example, 180 mmHg or 200 mmHg (a value higher than the patient's systolic blood pressure).
Then carefully open the valve 12 of the rubber pump 10 little by little to exhaust air from the exhaust port 11.

Here, being careful means that while the height of the mercury column 3 related to the exhaust is decreasing with the exhaust,
The blood pressure sound becomes audible, and the scale of the gauge 5 at the time the sound begins is read as the systolic blood pressure.As the height of the mercury column 3 due to exhaust air further decreases, the blood pressure sound eventually becomes inaudible, and this hearing loss occurs. This is because it is necessary to read the scale of the same gauge 5 when the patient gets tired as the diastolic blood pressure.

Furthermore, if the exhaust speed from the exhaust port 11 is natural exhaust, the air pressure that is the motive force is high at first, so the exhaust speed is high, and as the air pressure gradually decreases, the exhaust speed slows down. , the damping characteristics of the air pressure and the damping appear in a curved manner as shown in FIG.

Therefore, near the systolic blood pressure, the change in air pressure is larger than near the diastolic blood pressure, and the error in reading tends to be large. Conventionally, the opening degree of the valve 12 is controlled by hand, and at the beginning of the exhaust operation, it is opened narrowly and gradually gradually removed while exhausting air. Then, the degree of opening of the valve 12 was increased, the exhaust speed was kept constant, the damping characteristic approached a linear state, and the accuracy of reading the systolic blood pressure and diastolic blood pressure was made uniform.

However, since this method requires considerable skill, as shown in FIG. A rubber tube 1 is made by sandwiching the thin wire 19 and opening the slit 18 slightly.
7 is arranged inside the exhaust port 11.

This is because when the air pressure related to exhaust in the direction of the arrow is high, the elastic member 17 receives a strong compressive force from the outside toward the center, so the opening 20 of the slit 18
becomes smaller, thus suppressing the displacement, but
As the compressive force becomes weaker as the air pressure decreases, the opening 20 of the slit 18 becomes larger due to the restoring force of the elastic member 17 itself, making it easier to exhaust air. , which automatically stabilizes the displacement.

Furthermore, the next figure, FIG. 9, is a diagram showing a conventional blood pressure monitor controlled by a microprocessor. In the figure, 8 is a cuff that is worn around the upper arm, and 21 is a pump that sends air to the cuff 8. This cuff 8 and the pump 21 are connected by a rubber tube 22, and the pump 2
1 causes air to flow through the rubber tube 22 to the cuff 2.
sent to 1.

Further, the rubber pipe 22 is branched and multi-connected to a constant speed exhaust valve 23, a rapid exhaust valve 24, and a pressure sensor 25.

Among these, the constant speed exhaust valve 23 is a valve that automatically controls the exhaust amount to a constant level in order to gradually exhaust air from a high pressure state during blood pressure measurement, and the rapid exhaust valve 24
In an emergency, or after necessary blood pressure measurements are completed, the cap is opened rapidly to quickly exhaust the remaining air and relieve the upper arm from unnecessary constriction.

Further, the pressure sensor 25 is connected to the pump 21.
Changes in the pressure of the air sent from the air to the cuff 8 and changes in the air pressure after being exhausted by the constant speed exhaust valve 23 and the rapid exhaust valve 24 are detected via the multi-connected rubber tubes 22.

26 in the diagram is a microprocessor (μ-CPU)
Information regarding air pressure is obtained from the pressure sensor 25 mentioned above, and instructions are given to drive and stop the pump 21, and to open and close the constant speed exhaust valve 23 and the rapid exhaust valve 24.

This blood pressure measuring device using the microprocessor 26 does not use a stethoscope, and the systolic blood pressure and diastolic blood pressure are displayed digitally (not shown).

To use this blood pressure measuring device, first
When you put it on your upper arm, turn on the power, and then turn on the measurement switch (not shown), the pump 21 is activated and measures a value higher than the systolic blood pressure, for example 180 mmHg,
Or send air up to 200mmHg into the cuff 8,
Based on the pressure detected by the pressure sensor 25, the microprocessor 26 stops driving the pump 21.

Next, the constant speed exhaust valve 23 automatically opens gradually to exhaust the air while keeping the exhaust amount constant.

Due to the exhaust air, while the air pressure is decreasing at a constant speed, the systolic blood pressure is detected via the pressure sensor 25.
Diastolic blood pressure is measured and the microprocessor (μ-CPU) 26 stores those measurements.

When the measurement is finished, this microprocessor (μ
-CPU) 26 rapidly opens the rapid valve 24 to rapidly expel air and release the tightness of the upper arm.

[Problem that the invention seeks to solve]

The three main conventional examples have been explained above, but all of them use a method to control the exhaust volume in order to homogenize the accuracy of blood pressure measurement, which is the driving force behind the air pressure decay curve. Since the air pressure is initially high and gradually decreases, it has been extremely difficult to expect linearity over a wide range.

An object of the present invention is to solve the problem that it is difficult to maintain uniform blood pressure measurement accuracy over a wide range only by controlling the displacement amount.

[Means for solving problems]

In order to achieve the above object, the present invention provides the following blood pressure measuring device. That is, the present invention provides a pressurizing means for increasing the air pressure by supplying air into a cuff for measuring blood pressure that is worn on the upper arm of a subject, and a pressurizing means that is capable of exhausting the air sent into the cuff at a constant speed. a constant-speed exhaust means, a constant-speed exhaust auxiliary means to assist the constant-speed exhaust means, a rapid exhaust means capable of rapidly exhausting the air in the cuff after blood pressure measurement or in an emergency, and a pressure detection means for detecting;
The initial value and rate of air pressure drop required for blood pressure measurement are set, and when measuring blood pressure, the rate of air pressure drop is calculated based on the value detected by the pressure detection means, and compared with the set value, the drop in air pressure in the cuff is determined. Calculation to control the pressure increase means, constant speed exhaust means, and constant speed exhaust assist means to bring the speed close to the set descent speed set above, and to control the rapid exhaust means to rapidly exhaust the air in the cuff after blood pressure measurement. This is a blood pressure measuring device comprising a command means.

[Effect]

In the above configuration, the pressure increasing means supplies air into the cuff to increase the air pressure within the cuff, thereby generating air pressure necessary for blood pressure measurement.

The constant speed exhaust means exhausts the air in the arm cuff at a constant speed, thereby making the rate of decrease in air pressure constant.

The constant speed exhaust means auxiliary means assists the constant speed exhaust means.

The rapid exhaust means rapidly exhausts the air in the cuff to the outside after blood pressure measurement is completed or in an emergency.

The pressure detection means detects the air pressure within the cuff and transmits it to the calculation command means.

The calculation command means sets an initial value of air pressure and an exhaust speed necessary for blood pressure measurement, and also adjusts the air pressure inside the cuff to the setting based on the numerical information of the air pressure inside the cuff detected by the pressure detection means. When the initial value is reached, the air supply to the pressure increasing means is temporarily stopped, and constant speed exhausting is started by the constant speed exhausting means, thereby making it possible to measure blood pressure.

Further, when the rate of decrease of the air pressure in the arm cuff due to the calculation command means and the constant-speed exhaust is faster than the above-mentioned rate, air is supplied by the pressure increasing means to bring the rate of descent closer to the set rate, so that the rate of descent is lower than the set rate. If it is slow, the constant speed exhaust assisting means increases the displacement to bring the descending speed closer to the set speed.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Regarding embodiments of the present invention, how the structure of the present invention is actually embodied will be described below with reference to the drawings, together with its operation.

FIG. 1 is a block diagram showing one embodiment of the present invention, which includes a cuff 8, a motor pump 21, and a rubber tube 2.
2, constant speed exhaust valve 23, rapid exhaust valve 24,
Since the pressure sensor 25 and microprocessor (μCPU) 26 are almost the same as those in the conventional example shown in FIG. 9, the explanation of the overlapping parts will be omitted to avoid redundancy, and the different parts will be explained.

27 in the figure is a smooth buffer container, which is located between the cuff 8 and the motor pump 21, and absorbs subtle changes in air pressure, smoothing it out, and stabilizing it.

Further, 28 is an amplifier located between the motor pump 21 and the microprocessor (μ-CPU) 26, and supplies the power necessary for driving the motor pump 21 according to instructions from the microprocessor (μ-CPU) 26. .

Reference numeral 29 denotes a thin tube which is formed to have a narrow diameter to increase air resistance and limit the exhaust speed, and is attached to the tip of the constant speed exhaust valve 23.

This thin tube 29 normally has an air pressure of 40°C within the cuff 8.
The diameter is set so that a pressure drop rate of 3 to 4 mmHg/sec can be obtained when the pressure is ~50 mmHg, but when using the auxiliary capillary described later, the diameter may be made smaller.

Both constant speed exhaust auxiliary valves 23a and 23b are connected in parallel with the constant speed exhaust valve 23, and opening and closing thereof are controlled by a microprocessor 26.

Both 29a and 29b are auxiliary thin tubes, and have the same diameter as the thin tube 23, but may have different diameters if necessary.

These constant-speed exhaust auxiliary valves 23a, 23b and auxiliary thin tubes 29a, 29b are designed to control the motor by more rationally adjusting the constant-speed exhaust speed when the air pressure in the cuff decreases during blood pressure measurement. This reduces the load on the pump 21.

The motor pump 21 and the amplifier 28 constitute a pressure boosting means A, the constant speed exhaust valve 23 and the thin tube 29 constitute a constant speed exhaust means B, the constant speed exhaust auxiliary valve 23a, the thin tube 29a, and the constant speed exhaust means B. The auxiliary valve 23b and the thin tube 29b constitute constant speed exhaust auxiliary means _B1 and _B2 , respectively, the rapid exhaust valve 24 and the discharge port 30 constitute a rapid exhaust means C, and the pressure sensor 25 is a pressure detection means. , the microprocessor 26 is calculation command means.

FIG. 2 is a graph showing how the air pressure changes in the cuff according to an embodiment of the present invention, with the air pressure mmHg plotted on the vertical axis and the time t plotted on the horizontal axis.

In this curve, the air pressure is first raised in a short time to a constant height necessary for blood pressure measurement by the pressure increasing means A, and then it falls from the rising point over time. This part of the descending curve is generally 2
The attenuation curve due to natural exhaust as shown by the dashed dotted line shows that according to the present invention, the air pressure is supplemented by the pressure increasing means A and the rate of descent becomes constant.

FIG. 3 is a graph showing how the pressure increasing means A adjusts the rate of fall of the air pressure in the cuff to a constant level during blood pressure measurement.
Hg/sec is plotted and time t is plotted on the horizontal axis, so the feeling is different from that shown in FIG. 2, which plots pressure on the vertical axis.

According to this graph, the curve represents the change in the natural falling speed S ₁ of air pressure during blood pressure measurement, the straight line represents a constant set falling speed S ₀ , and the hatched part shows the change in the natural falling speed S ₁ The amount of air supplied by the pressure boosting means A at each point in time is shown, which is necessary to bring the speed of descent close to the set descent speed _S0 . That is,
It can be seen that a large amount of air supply is required at first, but gradually a smaller amount is required.

Figure 4 shows pressure boosting means A and constant speed exhaust assisting means B ₁
The amount of air supply required at each point in time is indicated by a hatch when _B2 is used, and the capillary tube 29 of the constant speed exhaust means B is of a narrow diameter.

That is, at the beginning of blood pressure measurement, the air pressure inside the cuff is high, so the constant speed exhaust valve 23 and the thin tube 2
By suppressing (throttling) the exhaust amount using only the constant speed exhaust means B consisting of This makes it easier to bring the air pressure drop rate closer to the set drop rate _S0 .

Next, as the exhaust action progresses and the air pressure in the cuff becomes lower than it was initially, the amount of exhaust air naturally decreases and the speed of air pressure drop _S1 slows down.

Therefore, in addition to the constant speed exhaust means B, a constant speed auxiliary means _B1 consisting of a constant speed auxiliary valve 23a and a thin tube 29a is simultaneously evacuated in parallel to enable mass exhaust, and at the same time, the booster means A is used to supply air. Make fine adjustments and set the falling speed of the air pressure inside the cuff S ₁ to the falling speed S ₀
I'm trying to get it close to.

Then, as the exhaust action progresses further and the air pressure in the wristband decreases, the amount of exhaust air decreases further, and the air pressure drop speed S ₁ slows down, making it impossible to maintain the set drop speed S ₀ .

Therefore, in addition to the constant speed exhaust means B and the constant speed exhaust auxiliary means B ₁ , constant speed exhaust auxiliary means B ₂ consisting of the constant speed exhaust auxiliary valve 23b and the thin tube 29b can be simultaneously exhausted in parallel.

As a result, the displacement suddenly increases, so by using the booster A in conjunction with the air supply and making fine adjustments, the air pressure drop speed S ₁ approaches the set drop speed S ₀ and the linearity of the drop speed is maintained. are doing.

In this figure, the exhaust means is in three stages (B→B+B ₁
→ B + B ₁ + B ₂ ) and sequentially expands the exhaust volume immediately after the start of blood pressure measurement (only B), so the amount of air supplied to pressure boosting means A can be saved, and the air pressure required for measurement can be reduced. It is possible to quickly supplement air supply over a wide range from high to low points, and the rate of air pressure drop in the arm cuff S ₁ can be reduced.
This shows that it is possible to smoothly approach the set descent speed _S0 .

According to this method, the air supply amount can be reduced because the adjustment is finer than in the case of FIG.
Motor pumps can be made smaller because they have less load.
It can be seen that it is economical.

Figure 5 is a flowchart outlining the operational flow of the enforcement order. First, the cuff is attached to the upper arm, the power is turned on, and the microprocessor generates the air pressure necessary to measure blood pressure. initial value
V ₀ and the rate of decrease in the atmospheric pressure required for blood pressure measurement S ₀
and is set 42.

Next, the microprocessor activates the motor pump 43 via the amplifier to supply air into the cuff and rapidly raise the pressure.

If the boost does not reach the set initial value V ₀ (No), the boost is continued 44 until it becomes equal to the initial value V ₀ .

When the air pressure increases to the set air pressure _V0 , the constant speed exhaust valve is opened and air is exhausted from the thin tube at a constant speed. When the air pressure starts to drop,
At the same time, blood pressure measurement is started 46.

The air pressure drop rate value S ₁ is determined by the pressure sensor and microprocessor to the drop rate set value S ₀ of the above settings.
It is compared with 47.

Here, the purpose of this invention is to solve the problem that in the case of natural exhaust, it is difficult to accurately read the systolic blood pressure because the air pressure drop rate S ₁ is initially large. At the beginning, it is practically impossible for the descent speed S ₁ to be less than the set value S ₀ , so if you have not started the air supply,
Step 47 is always Yes.

When S ₁ is larger than the set speed of descent S ₀ (Yes), the motor pump supplies air 48 into the cuff to slow down the speed of drop S ₁ of the air pressure and bring it closer to the set speed S ₀ .

If S 1 is not larger than the set value S ₀ (No) in the comparison 47 of the air pressure drop rate S ₁ and _the set value S ₀ of the fall rate, a further comparison is made in the next step 49 .

If the result of the comparison in step 49 is Yes, the auxiliary valve ( _B1 in this case) is used to exhaust the air (50), and in parallel with the constant speed exhaust valve opening 45, a large amount of air can be exhausted. In addition, step 4
Return to 7.

In this case, in step 47, it is determined that the air pressure drop rate S ₁ has become larger than the set value S ₀ due to the large amount of exhaust gas (Yes), and air is supplied again by the motor pump (step 48), and then return.

Repeat this and at step 47 (No)
That is, when the air pressure drop speed S ₁ becomes smaller (slower) than the set drop speed S ₀ , the auxiliary valve (in this case B ₂ ) is made to be able to exhaust air again in parallel,
By evacuation of a larger amount, the air pressure drop rate S ₁ is slowed down, and together with the air supply pressure being increased 48 by the motor pump, the air pressure drop rate is brought closer to the set rate S ₀ .

If the answer in step 49 is No, this means that the air pressure drop speed S ₁ is the same as the set speed S ₀ , which is the object of the present invention.

In this way, accurate blood pressure measurement is performed while exhausting at the same speed as the target set speed _S0 , and if the determination 51 is whether the measurement has been completed or not, the steps 47 to 51 are repeated, and the steps 47 to 51 are repeated.
In this case, the rapid exhaust valve is opened to rapidly exhaust 52 the unnecessary residual air in the cuff from the exhaust port, and the flowchart for blood pressure measurement ends 53.

When the air pressure drop rate S ₁ is smaller than the set value S ₀ , the auxiliary valve is opened to exhaust the air 50 and the air pressure fall rate is increased to enable blood pressure measurement. Furthermore, if the air pressure drop speed _S1 is not smaller than the set speed, constant speed exhausting is continued.

During this time, blood pressure measurement continues, and the pressure sensor and microprocessor measure systolic and diastolic blood pressure.
It monitors whether the blood pressure measurement has been completed, and if it has not finished, it continues to monitor, and when it is determined that the blood pressure measurement has finished, the rapid exhaust valve is opened and the unnecessary residual air in the cuff is rapidly exhausted from the exhaust port 52. , the blood pressure measurement ends 53.

In this way, in this embodiment, blood pressure is measured while exhausting with a constant speed exhaust valve, and the constant speed exhaust speed S ₁ is constantly compared with the set exhaust speed S ₀ using a pressure sensor and a microprocessor. When the rate of decrease in air pressure S ₁ due to the exhaust air is faster than the set speed S ₀ , air is supplied via an amplifier and driven by a motor pump to bring the air pressure closer to the set speed S ₀ . Also, the air pressure drop rate S ₁
When the speed is slower than the set speed S ₀ , the constant speed exhaust auxiliary valve is opened at the same time to facilitate the exhaust, and in this case, the supply air pressure is also increased to bring it closer to the set speed S ₀ , so the air pressure inside the cuff is Over a wide range from high to low, the air pressure drop speed S ₁ is linear, approximating the preset speed S ₀ , and both systolic and diastolic blood pressure can be measured accurately. be.

〔Effect of the invention〕

As described above, according to the present invention, since the pressure increase means, constant speed exhaust means, rapid exhaust means, pressure detection means, and calculation command means are provided, the air pressure in the cuff is increased to a constant height required for measurement. , constant speed exhaust,
By simultaneously supplying air in an active manner using a pressurizing means during constant-speed evacuation, it is possible to supplement the air pressure and keep the air pressure drop rate in the cuff constant over a wide range, making it possible to accurately measure blood pressure. Now I can do it.

In addition, during constant-speed exhaust, the constant-speed exhaust volume is increased by constant-speed exhaust auxiliary means as necessary, and
At the same time, since the air pressure is supplemented by the pressure boosting means, the adjustment amount of the pressure boosting means is small, and the pressure boosting means only needs to have a small capacity, so it is economical.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Fig. 2 is a diagram showing changes in the air pressure in the cuff of the same embodiment, Fig. 3 is an explanatory diagram of adjusting the rate of decrease in air pressure by the pressure increasing means of the same embodiment, and Fig. 4 is a diagram showing the pressure increasing means and constant speed of the same embodiment. FIG. 5 is a flowchart showing an overview of the operation flow of the same embodiment, and FIGS. 6 to 9 are explanatory diagrams of the conventional example. 8... Bracelet, 25... Pressure sensor (pressure detection means), 26... Microprocessor (calculation command means), A... Pressure boosting means, B... Constant speed exhaust assisting means.

Claims (1)

[Claims] 1. Pressurizing means for increasing air pressure by supplying air into a cuff for blood pressure measurement worn on the upper arm of a subject;
a constant-speed exhaust means capable of exhausting the air sent into the arm cuff at a constant speed; a constant-speed exhaust auxiliary means for assisting the constant-speed exhaust means; A rapid evacuation means capable of rapidly evacuation in an emergency, a pressure detection means for detecting the air pressure in the cuff, and an initial value of air pressure necessary for blood pressure measurement and an air pressure drop rate set, and the pressure detection means detects when blood pressure is measured. A pressure increase means, a constant speed exhaust means, and a constant speed exhaust auxiliary means calculate the air pressure drop rate based on the set value and compare it with the set value to bring the rate of fall of the air pressure in the cuff closer to the set set fall speed. A blood pressure measuring device comprising calculation command means for controlling a rapid exhaust means to perform air supply and exhaust at the same time and rapidly exhaust the air pressure in the arm cuff after blood pressure measurement.