JPH0369530B2 - - 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 5. There is something like that.

In the figure, 1 is the case of the blood pressure monitor, and this case 1
A mount 2 that can be folded and stored is provided inside the mount 2, and a glass tube 4 that forms a mercury column 3 by vacuum-sealing mercury is attached to the mount 2, as well as a gauge 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 in 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 line 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, in order to automatically adjust the exhaust speed to a constant level, 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.

Further, FIG. 8 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 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 air pressure in the cuff;
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. Air supply and exhaust are performed simultaneously by controlling the pressure increasing means and constant speed exhaust means to bring the speed close to the set lowering speed, and after the blood pressure measurement, the rapid exhaust means is used to rapidly exhaust the air in the cuff. This blood pressure measuring device is equipped with a calculation command means for controlling the blood pressure.

[Function] 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 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 the measurement 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, the calculation command means determines that when the rate of fall of the air pressure in the cuff due to constant-speed exhaust is faster than the above-mentioned speed, air is replenished by the pressure increase means at the same time during the evacuation to bring the rate of descent closer to the set speed, and the air pressure is lowered. When the speed is lower than the set speed, the amount of air supply is adjusted and reduced to bring the rate of descent 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,
Pressure sensor 25, microprocessor (μ-
Since the CPU 26 is almost the same as the conventional example shown in FIG. 8, the explanation of the overlapping parts will be omitted to avoid redundancy, and the different parts will be explained.

Reference numeral 27 in the figure indicates a smooth buffer container, which is located between the cuff 8 and the motor pump 21 and absorbs minute changes in air pressure to smooth and stabilize the air pressure.

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.
Set the diameter to a pressure drop rate of 3 to 4 mmHg/sec when the pressure is ~50 mmHg.

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, and the rapid exhaust valve 24 and the discharge port 30 constitute a rapid exhaust means. The pressure sensor 25 is a pressure detection means, and the microprocessor 26 is a 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 advance by the pressure increasing means A to a certain height required for blood pressure measurement in a short period of time, and then falls from that rising point over time. This part of the descending curve generally shows an attenuation curve due to natural exhaust as shown by the two-dot chain line, but according to the present invention, it shows that the air pressure is supplemented and the descending speed 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.
Since we took Hg/sec and time t on the horizontal axis, the second
The feel is different from the picture.

According to this graph, the curve represents the change in the natural rate of decrease S ₁ of air pressure during blood pressure measurement, the straight line represents the constant set rate of decrease S ₀ , and the hatched part represents the change in the rate of decrease S ₁ when the air pressure is measured. It shows the amount of air supplied by the pressure boosting means A at each point in time required to bring the speed close to _S0 . In other words, it can be seen that a large amount of air supply is required at first, but gradually a smaller amount is required.

FIG. 4 is a flowchart showing the outline of the operation flow of the same embodiment. First, the cuff is attached to the upper arm and the power is turned on to start 41. The microprocessor calculates the air pressure necessary for blood pressure measurement. initial value of
V ₀ and the rate of decrease in air pressure required for blood pressure measurement
_S0 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 initial value V ₀ of the setting is not reached due to the voltage increase (No), continue increasing the voltage until it becomes equal to V ₀ 4
4.

When the air pressure increases to the set air pressure _V0 (Yes), the constant speed exhaust valve is opened and air is exhausted from the thin tube at a constant speed (45), and when the air pressure begins to fall, blood pressure measurement is simultaneously 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,
The answer will definitely be yes.

When S ₁ is larger than the descending speed setting value S ₀ (Yes), air is supplied into the arm cuff by the motor pump.
and slow down the air pressure drop speed S ₁ to the set speed
Bring S closer to ₀ .

If S 1 is not greater than the set value S ₀ in the comparison 47 of the air pressure drop rate S ₁ and the set value S ₀ of the fall rate, if 47 _No , a further comparison is made in the next step 49 .

If the result of the comparison in step 49 is Yes, the air supply amount is too large, so the air supply is adjusted (reducing the air supply amount) (50), and the rate of air pressure drop in the cuff S ₁ is brought closer to the set speed _S0 .

If the answer in step 49 is No, this means that the air pressure drop rate _S1 is the same as the set speed _S0 , which is the object of the present invention.

In this way, accurate measurements of systolic blood pressure, diastolic blood pressure, etc. are performed while exhausting at the same speed as the target set speed S ₀ , and if the determination 51 of whether the measurement has been completed or not is No (not completed). is step 4
Steps 7 to 51 are repeated, and in the case of Yes (end), the rapid exhaust valve is opened and the unnecessary residual air in the cuff is rapidly exhausted 52 from the exhaust port, and the series of blood pressure measurement flowcharts are completed 53.

That is, the present invention is characterized in that constant-speed exhaust and air supply by increasing pressure are performed simultaneously.

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 due to exhaust air S ₁ is faster than the set speed S ₀ , air is supplied by the motor pump via the amplifier to bring it closer to the set speed S ₀ , so that the air pressure can be reduced over a wide range from high to low air pressure areas. The air pressure drop speed S ₁ becomes a linear value that approximates the preset set speed S ₀ , and both the systolic blood pressure and the diastolic blood pressure can be accurately measured in blood pressure measurement.

〔Effect of the invention〕

As described above, according to the present invention, the blood pressure measuring device is equipped with a pressure increase means, a constant speed exhaust means, a rapid exhaust means, a pressure detection means, and a calculation command means. After the pressure is increased to 1, the air pressure is increased to a constant rate, the air is exhausted at a constant speed, and air is supplied in an active manner using the pressure increasing means during the constant speed exhaust, thereby supplementing the air pressure and keeping the rate of air pressure drop in the cuff constant over a wide range. This has the effect of making it possible to measure blood pressure accurately.

[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 air pressure in the cuff of the same embodiment, Fig. 3 is an explanatory diagram of adjusting the speed of air pressure drop by the pressure increasing means of the same embodiment, and Fig. 4 is an overview of the flow of operation of the same embodiment. Flowcharts showing the above and FIGS. 5 to 8 are explanatory diagrams of conventional examples. 8... Bracelet, 25... Pressure sensor (pressure detection means), 26... Microprocessor (calculation command means), A... Pressure increase means, B... Constant speed exhaust means, C
...Rapid exhaust 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 rapid exhaust means capable of rapidly exhausting the air within the arm cuff after blood pressure measurement is completed or in an emergency; a pressure detection means for detecting the air pressure of the air pressure, and an initial value of the air pressure necessary for blood pressure measurement and a rate of decrease in the air pressure, and when measuring blood pressure, the rate of decrease in the air pressure is calculated based on the value detected by the pressure detection means, and the rate of decrease in the air pressure is calculated based on the value detected by the pressure detection means, and the rate of decrease in the air pressure is calculated based on the value detected by the pressure detection means. By comparison, air supply and exhaust are performed simultaneously by controlling the pressure increasing means and constant speed exhaust means to bring the rate of fall of the air pressure in the cuff closer to the set rate of fall, and after blood pressure measurement, the air in the cuff is A blood pressure measuring device, comprising calculation command means for controlling a rapid exhaust means to rapidly exhaust the blood pressure.