JPH0349573B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to blood pressure monitors. More specifically,
The present invention relates to a blood pressure monitor that maintains a constant amount of pressure reduction, that is, a displacement amount for each beat, even if the pulse rate varies from person to person.

Description of the Prior Art Blood pressure monitors are generally used to monitor the health status of patients or healthy people. This blood pressure monitor wraps the cuff (or cuff) around the patient's arm, supplies air into the cuff to pressurize it until blood circulation stops, and then gradually exhausts the air inside the cuff. When blood pressure begins to flow, a special sound called Korotkoff sound is detected and determined, and this is taken as the systolic blood pressure value. Here, the Korotkoff sound is when the cuff pressure is between the systolic blood pressure value and the diastolic blood pressure value, that is, while the blood vessels are distorted by the cuff pressure.
A special sound that can be heard when a stethoscope is placed over an artery as it pulsates. Note that in the following explanation, the Korotkoff sound will be abbreviated as the K sound. Then, when the air inside the cuff is further evacuated and the pressure is reduced, the K sound can no longer be heard or the sound quality suddenly drops, and the pressure value at that time is taken as the diastolic blood pressure. In this way, systolic blood pressure and diastolic blood pressure are measured.

By the way, it is empirically known that the appropriate rate of exhaustion during measurement with a blood pressure monitor is a rate of descent of 2 to 3 mmHg per beat of the person being measured. However, conventional blood pressure monitors either exhaust the air inside the cuff at a constant exhaust speed regardless of the pulse cycle or pulse rate of the person being measured, or manually operate the cuff in advance to find the ideal exhaust speed. It was set by.

By the way, another prior art related to this invention is disclosed in Japanese Unexamined Patent Publication No. 55-29304. This bulletin states that the pressure value is read every time the pulse of the person being measured is detected, and the pressure difference (number indicating pressure drop) in one beat period is displayed on the display, and the measurer or person can read the pressure value on the display. A sphygmomanometer is disclosed that adjusts a leakage valve to a prespecified value based on the sphygmomanometer. However, this publication does not disclose anything about controlling the valve for leaking the air sealed in the air sac (cuff).

Of the two prior art techniques mentioned above, in the former, even though the pulse period differs from person to person, when exhausting at a constant pumping speed, the rate of pressure drop per beat varies from person to person. There was a problem with poor measurement accuracy. In addition, although the latter allows the exhaust speed to be set according to the pulse rate, the valve must be adjusted manually, which tends to cause overresponses, and the exhaust speed must be set to an appropriate value. It takes a long time to do so. Therefore, in order to perform the above settings prior to blood pressure measurement, it is necessary to set the pressure value at the time of starting decompression to a value sufficiently higher than the systolic blood pressure value. There were problems in that not only congestion was likely to occur, but also the measurement time was long.

Summary of the Invention In summary, the present invention detects the pulse cycle of a subject and makes the displacement per beat constant based on the pulse cycle of the subject. For this purpose, the storage means stores data for changing the control amount in the displacement adjusting means so that the displacement per pulse is constant for each pulse cycle. The control amount of the displacement adjusting means is changed based on the control amount data corresponding to the detected pulse cycle.

According to this invention, the exhaust volume can be automatically adjusted and made constant in relation to the pulse cycle of the person to be measured, and the exhaust volume per beat can be made uniform, so it is possible to Blood pressure can always be measured with high accuracy regardless of differences in blood pressure.

In addition, the control amount data corresponding to the pulse cycle that has been set and stored in advance is read out, and the displacement adjustment means is controlled using this control amount data, so the desired appropriate value can be set in a short time and the control is automatically controlled. As a result, a stable pumping speed can be obtained from the start of pumping without overresponsiveness, so congestion does not occur and the measurement time can be shortened.

In a preferred embodiment of the present invention, during decompression, it is determined whether the displacement per beat is correlated with the control amount data, and if it is not correlated with the control amount data, the displacement is automatically adjusted within a minute range. Fine adjustments can be made to further improve detection accuracy.

Therefore, an object of the present invention is to automatically control and keep the displacement per beat (or pressure drop rate) constant regardless of the difference in the pulse cycle of the subject, without causing congestion. It is an object of the present invention to provide a blood pressure monitor capable of measuring blood pressure with high precision in a short time.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of a blood pressure monitor 10 according to one embodiment of the present invention. In the configuration, the blood pressure monitor 10 of this embodiment includes a central processing unit (hereinafter referred to as CPU) 11. The CPU 11 includes work register areas (hereinafter simply referred to as registers) 11a to 11d. The register 11a is loaded with the pressure value Pn for the period of one beat measured this time. The register 11b stores the detected pressure value in the immediately preceding one-beat period.
Load Pn _-1 . The register 11c is loaded with the pressure change value ΔP (=Pn−Pn ₋₁ ) for one beat. The register 11d loads the control amount data x.

A setting switch 12 and a setting table 20 are connected to the CPU 11 . Setting switch 12
The control amount data for controlling the rate of pressure drop per beat set in the setting table 20 selects either a 1 mmHg drop per beat or a 2 mmHg drop per beat. It is. The setting table 20 is
For example, a read-only memory (ROM) is used, the details of which will be described in FIG. 2 below.

The control amount data (digital value) output from the CPU 11 is given to a digital/analog (hereinafter referred to as D/A) converter 13 . The D/A converter 13 converts the control amount data into an analog value, which is supplied via the amplifier 14 as a control signal for the opening degree of the solenoid valve 15, which is an example of the displacement adjusting means. The solenoid valve 15 is
It is provided in connection with the exhaust passage of the cuff (or cuff) 16, and the exhaust speed (i.e. 1
This is to adjust the displacement per beat). Air is supplied to the cuff 16 from a pressurizing pump 17, which is an example of pressurizing means. A pressure sensor 18a, which is an example of pressure detection means, is provided in connection with the exhaust passage of the cuff 16. The pressure sensor 18a detects the pressure within the cuff 16 and provides its detection output to the CPU 11.
Further, in relation to the cuff 16, a K sound sensor 18b is provided. The K-sound sensor 18b is used to detect the pulse rate or pulse cycle when increasing the pressure inside the cuff 16, and detects the pulse and K-sound when the air inside the cuff 16 is exhausted and depressurized. used for. The output of the K sound sensor 18b is sent to the amplifier 1.
9 to the CPU 11.

FIG. 2 is a diagram schematically showing data set and stored in the setting table 20. As shown in FIG. In the figure, a setting table 20 presets and stores the displacement amount (that is, the pressure drop value) in one pulse period for each pulse period or a certain range of pulse numbers per unit time. For example, if the pressure value that should drop per beat is 1 mmHg for each range of 10 pulse rates per minute, then the pulse rate is 31 mmHg per minute.
9 to 40, a voltage of 9 volts is applied to the coil of the solenoid valve 15, and thereafter, the voltage value is set lower by 0.5 volts every time the pulse rate increases by 10 per minute. More preferably, for each predetermined range of pulse rate per unit time, the pressure value to be depressurized per night is set to two or more levels: a first pressure value (1 mmHg) and a second pressure value (for example, 2 mmHg). Set in stages. By making the pressure drop per beat different and selecting it with the setting switch 12, you can switch between when you want to measure blood pressure accurately and when you want to measure it quickly without worrying about accuracy. It has the advantage of being able to be measured.

FIG. 3 is a diagram showing the relationship between the voltage applied to the electromagnetic valve 15 and the pumping speed. In the figure, when the horizontal axis is the applied voltage (V) to the coil of the solenoid valve 15 and the vertical axis is the pumping speed (mmHg/sec), the cuff 16
When the air capacity inside is 500c.c., the applied voltage and pumping speed are inversely proportional as shown in the figure. That is, the electromagnetic valve 15 works so that the higher the applied voltage, the smaller the valve opening, and the lower the applied voltage, the larger the valve opening.

FIG. 4 is a flowchart for explaining the operation of one embodiment of the present invention. Next, the specific operation of this embodiment will be explained with reference to FIGS. 1 to 4.

Prior to the blood pressure measurement operation, the cuff 16 is wrapped around the arm or predetermined region of the subject. Thereafter, in step 1, the pressurizing pump 17 is driven to supply air to the cuff 16, thereby starting a pressurizing operation. In step 2, the CPU 11 measures the pulse rate per unit time (for example, one minute) based on the output of the K sound sensor 18b. In step 3, the CPU 11
The pressure within the cuff 16 is measured based on the output of the pressure sensor 18a. Subsequently, in step 4, it is determined whether the measured pressure value exceeds a set value (a pressure value greater than the systolic blood pressure value).
If the detected pressure value is less than the set value, proceed to step 2~
The operation of step 4 is repeated.

When the detected pressure value exceeds the set value, the pressurizing pump 17 is disabled in step 5 to stop the pressurizing operation. In step 6, the falling pressure value per beat set by the setting switch 12 is read. In step 7, the setting table 20 is searched based on the pulse rate per unit time measured in step 2 and the pressure drop value per beat read in step 6. For example, if the pulse rate per unit time is 60 to 70 and the pressure drop value is 1 mmHg,
7.5V control amount data is read. Step 8
At , the control amount data x is given to the D/A converter 13 . The D/A converter 13 converts the control amount data x into an analog value and applies it to the coil of the electromagnetic valve 15 via the amplifier 14. Depending on the solenoid valve 1
5 adjusts the opening degree of the valve based on the control amount data so that the pressure drop value per beat is 1 mmHg.

In step 9, blood pressure is measured based on the output of pressure sensor 18a. In step 10, it is determined that the blood pressure measurement operation has not been completed. In step 11, pulse detection is performed. In step 12, it is determined whether there is a pulse. If it is determined that there is no pulse, that is, the period of one beat has not elapsed,
The operations of steps 9-12 are repeated. One of these days,
When there is a pulse, that is, one beat period has elapsed, the process advances to step 13. In step 13, the detected pressure value (Pn) is loaded into register 11a. At this time, the register 11b contains the pressure value (Pn _-1 ) detected during the immediately preceding one beat period.
is loaded. In step 14, the pressure value Pn detected this time is subtracted from the pressure value Pn _-1 measured in the immediately preceding period of one beat to obtain the value of pressure change (ΔP) in one beat. This ΔP is loaded into the register 11c. In step 15, the contents of the register 11a (Pn) are transferred to the register 11c and loaded as the previous detected pressure value (Pn _-1 ).In step 16, the drop per beat set by the setting switch 12 is The pressure value (or displacement) is read.
In step 17, ΔP reaches the set value (1 mmHg/
It is determined whether or not there is a beat). If the pressure within the cuff 16 drops by the set value during one beat, the process returns to step 8, and steps 8 or 8 described above are performed.
The operation of step 17 is repeated. On the other hand, if ΔP is not equal to the set value, proceed to step 18. In step 18, it is determined whether ΔP is smaller than a set value. If it is determined that ΔP is smaller than the set value,
In other words, when the falling pressure value per beat is smaller than 1 mmHg, it is necessary to decrease the control amount data (x) by a minute amount Δx to increase the falling pressure value per beat. Therefore, in step 19, the contents (x) of the register 11d are changed to a minute amount (Δx).
will be subtracted. Here, Δx is the amount of change per rank in pulse rate per unit time (0.5V)
is chosen to be much smaller than (for example, 0.01). After this, the operations of steps 8 to 17,
Alternatively, by repeating steps 8 to 19, the pressure drop per beat can be adjusted to the set value (1 mm
Hg).

On the contrary, in step 18 mentioned above,
If it is determined that ΔP is larger than the set value, it is necessary to increase the control amount data (x) by a minute amount to reduce the falling pressure value per beat. Therefore, in this case, in step 20,
The minute control amount data (Δx) is added to the contents (x) of the register 11d. Then step 8 as mentioned above.
Steps 8 to 27 or steps 8 to 18 and 20 are repeated.

As described above, according to this embodiment, the falling pressure value per beat (that is, data correlated to the exhaust speed) is registered in the setting table for each predetermined range of the number of pulses per unit time, that is, the cycle of one beat. When the pressure inside the cuff is reduced based on the pulse cycle during pressurization, the pressure drop value (or displacement) per beat is automatically adjusted, so it can be used for people with high or low pulse rates. Regardless of the situation, blood pressure can be measured with a constant pressure drop value, which has the advantage of improving blood pressure measurement accuracy. In addition, the control amount data corresponding to the pulse cycle set and stored in advance is read out, and the displacement adjustment means is controlled by this control amount data.
The desired and appropriate value can be set in a short time, and control is performed automatically, so there is no overresponse and a stable pumping speed can be obtained from the start of pumping, so there is no congestion and the measurement time is shortened. It is also short. Furthermore, if you set the drop pressure value per beat to at least two levels, you can freely switch between when you want to measure blood pressure with high precision and when you want to measure relatively quickly without worrying about accuracy. There is also the advantage of being able to

As described above, according to the present invention, the displacement per beat (or pressure drop rate) can be automatically controlled and kept constant regardless of the difference in the pulse cycle of the subject, thereby preventing congestion from occurring. A blood pressure monitor capable of measuring blood pressure with high precision in a short time without any problems can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a blood pressure monitor according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing the storage area of the setting table. FIG. 3 is a diagram showing the relationship between the voltage applied to the coil of the solenoid valve and the pumping speed. FIG. 4 is a flowchart for explaining the operation of one embodiment of the present invention. In the figure, 10 is a blood pressure monitor, 11 is a CPU which is an example of a control means, 12 is a setting switch, and 13 is a D/
A converter, 14 and 19 are amplifiers, 15 is a solenoid valve,
16 is a cuff, 17 is a pressure pump, 18a is a pressure sensor, 18b is a K sound sensor, and 20 is a setting table.

Claims (1)

[Scope of Claims] 1. A cuff that is wrapped around a predetermined part of a person whose blood pressure is to be measured; air is supplied to the cuff to increase the pressure within the cuff to a predetermined set value that exceeds the systolic blood pressure of the person being measured; a pressurizing means for pressurizing the cuff; a pressure detecting means for detecting the pressure within the cuff; a period detecting means for detecting the period of the subject's pulse; a displacement adjusting means for adjusting the displacement when reducing the pressure within the cuff. , storage means for presetting and storing control amount data for determining the control amount of the displacement adjusting means for each of a plurality of pulse cycles in each predetermined range, and the pressure detection means detecting the pressure of the predetermined set value. control means for reading control amount data corresponding to the period of the output of the period detection means from the storage means and automatically controlling the displacement of the displacement amount adjusting means according to the control amount data; A blood pressure monitor with 2. The storage means includes a storage area for storing control amount data for each pulse cycle for at least two stages of exhaust speed, and the control amount data has a relationship inversely proportional to the exhaust speed for the same pulse cycle. The sphygmomanometer according to claim 1, wherein the sphygmomanometer is selected such that: 3. The control means detects that the output of the pressure detection means exceeds a certain pressure reduction range when controlling the displacement of the displacement adjustment means based on the control amount data read from the storage means. The sphygmomanometer according to claim 1 or 2, further comprising fine adjustment means for finely adjusting the control amount, as appropriate. 4. The fine adjustment means controls the displacement of the displacement adjustment means by a minute amount using data of a minute control amount that is relatively smaller than the control amount every time the period detection means detects a certain period. The blood pressure monitor according to claim 3.