JPH06107B2 - Electronic blood pressure monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention detects a pulse wave amplitude in the process of compressing an artery with a cuff and changing the cuff pressure, and determines the blood pressure using this pulse wave amplitude. About electronic blood pressure monitor.

(B) Conventional Technique Generally known electronic blood pressure monitors are of the so-called arm type in which an arm band is wrapped around the upper arm to compress an artery. However, the arm-type electronic sphygmomanometer is relatively large, is inconvenient to carry, etc., and it is troublesome to roll the arm when wearing the armband, so the inventor of this application has a cuff for a finger. I have already filed a separate application for an electronic blood pressure monitor for finger compression.

This electronic blood pressure monitor for fingers detects the amplitude of a pulse wave signal for blood pressure measurement, and determines the blood pressure from the change in the pulse wave amplitude and the cuff pressure. Then, the pulse wave amplitude is detected by extracting the pulse wave from the pulse wave component output of the pulse wave sensor, calculating the difference between the maximum value and the minimum value of the pulse wave component for each pulse wave, and calculating the difference value. This is done by setting the pulse wave amplitude. In this case, the pulse wave component a (t) output from the pulse wave sensor is the fifth
As shown in FIG. 5A, in detecting the pulse wave from the pulse wave component a (t), as shown in FIG. 5 (B), the differential value a ( t) / dt is calculated, and this differential value a (t)
When / dt exceeds the threshold level TH (negative direction in the figure), it is determined that there is a pulse wave, and the period of the next pulse wave from this pulse wave is set as one beat, and the maximum and minimum values of the pulse wave component in this section are set. The difference value is used as the pulse wave amplitude.

(C) Problems to be Solved by the Invention In the above electronic blood pressure monitor for fingers, if the threshold level TH is set to a low value to detect one pulse wave, there is a problem that noise is picked up, so it cannot be made too small. However, when the threshold level TH is large, in the case of a person with a small pulse wave amplitude or a person with a gentle change in the pulse wave, the differential value does not exceed the threshold level and the pulse wave is not detected. Aj is shown in FIG. 5 (C), and a sufficient number of data cannot be obtained and accurate blood pressure measurement cannot be performed.

In view of the above, the present invention makes it possible to obtain necessary data even when the pulse wave amplitude that is often seen in women is small, or even when the pulse wave that is seen in people with abnormal blood vessels is gentle and accurate. It is intended to provide an electronic blood pressure monitor that can perform measurement.

(D) Means and Actions for Solving Problems As shown in FIG. 1, the electronic sphygmomanometer of the present invention has a cuff 1 for compressing an artery of a body to be measured, and pressurizing or depressurizing the inside of the cuff. The pressure system 2, the cuff pressure sensor 3 that detects the pressure of the cuff, the pulse wave sensor 4 that detects the pulse wave component in the pressure change process of the cuff, and the presence or absence of the pulse wave is determined by the output of this pulse wave sensor. The pulse wave presence / absence determining means 5 and the difference between the maximum value and the minimum value of the pulse wave sensor output for each pulse wave is used as the pulse wave amplitude value while the pulse wave presence / absence determining means determines the presence of the pulse wave. The pulse wave amplitude is the difference between the maximum value and the minimum value of the pulse wave sensor output at constant intervals while the pulse wave existence is not determined by the pulse wave amplitude detecting means 6 of No. 1 and the pulse wave presence / absence determining means. 2, the pulse wave amplitude detecting means 7, the cuff pressure from the cuff pressure sensor, and the first and second pulse wave amplitude detecting means. Blood pressure determining means 8 for determining the blood pressure based on the pulse wave amplitude from the step.

In this electronic sphygmomanometer, when the pulse wave is detected by the pulse wave presence / absence determining means, the pulse wave amplitude is detected by the first pulse wave amplitude detecting means for each pulse wave, and conversely, by the pulse wave presence / absence determining means. If no wave is detected, the pulse wave amplitude is detected by the second pulse wave amplitude detecting means at regular intervals, and the pulse wave amplitude data necessary for blood pressure determination is obtained from the data obtained by both pulse wave amplitude detecting means. .

(E) Examples Hereinafter, the present invention will be described in more detail with reference to Examples.

FIG. 2 is a schematic block diagram of a finger electronic blood pressure monitor in which the present invention is implemented.

In FIG. 2, the cuff 11 is formed of a rubber bag and has a cylindrical shape that allows insertion of fingers.
1 is provided with a pulse wave sensor 12, and the pulse wave signal detected by the pulse wave sensor 12 is taken into an MPU (microprocessor unit) 15 via an amplifier 13 and an A / D converter 14. Has become.

Further, the cuff 11 is connected to the pressure sensor 17 by the rubber tube 16, is also connected to the air buffer 18, and is further connected to the fine speed exhaust valve 19 and the quick exhaust valve 20. Also,
The air buffer 18 is connected to a pressurizing pump 21 via a check valve 22. The pressurizing pump 21 includes a motor (air buffer 18, quick exhaust valve 19,
A pressure system is composed of the rapid exhaust valve 20, the pressurizing pump 21, etc.).

The cuff pressure detected by the pressure sensor 17 is amplified by the amplifier 23, and is taken into the MPU 15 via the A / D converter 14.

The MPU 15 has a built-in memory for storing programs and calculated values, a function for taking in pulse wave data and cuff pressure data by switching from the A / D converter 14, a function for turning on / off the pressurizing pump 21, and a rapid exhaust. Turn valve 20 ON / OFF
Function, the function of determining the presence or absence of a pulse wave from the output of the pulse wave sensor 12 after the start of operation, the function of detecting the pulse wave amplitude of each pulse wave with the presence of the pulse wave, and the constant time (without the pulse wave) Example: 1.5
Function to detect pulse wave amplitude every second), systolic blood pressure (SYS), diastolic blood pressure (DIA) from cuff pressure and both pulse wave amplitude data
And the like for determining the blood pressure value.

Further, the determined blood pressure value, that is, the systolic blood pressure (SYS) and the like is output from the MPU 15 and displayed on the display 24,
In addition, the notification sound is output by the buzzer 2 according to a command from the MPU 15.
5 is output.

Next, the operation of the electronic blood pressure monitor of the above embodiment will be described with reference to the control flow chart shown in FIG.

Before starting the measurement, the measurer inserts the index finger into the ring of the cuff 11 and turns on a power switch (not shown) attached to the MPU 15. As a result, the operation is started. First, at step ST (hereinafter referred to as ST) 1, all display segments of all digits of the display 24 are lit for 1.5 seconds (ST2), and then the rapid exhaust valve 20 is opened (ST3). Display 2
The rapid exhaust mark of 4 blinks (ST4). continue,
It is determined whether or not the cuff pressure is 0, and if it is not 0, the process waits until it becomes 0 (ST5). When the cuff pressure becomes 0, the exhaust mark is turned off (ST6) and the preparation completion mark is turned on (ST7). This allows the measurer to know that the preparation is complete.

Here, if the start switch also attached to the MPU 15 is turned on, the determination in ST8 becomes YES and the ready mark disappears (ST9). Subsequently, an LED (not shown) indicating that the measurement is in progress is turned on (ST10), the rapid exhaust valve 20 is closed (ST1), and the cuff 11 is pressurized to the set value (ST12). The set value here means the pressurization target value set to a value 20 to 30 mmHg higher than the systolic blood pressure value of the subject. When the pressure is increased to the set value, the pressure pump 21 is turned off, and it is determined whether or not the current pressurization is repressurization (ST13). If the pressurization is the first pressurization, the process proceeds to ST15, and the slow exhaust valve 19 is used. Starts slow exhaust. After all, since the pulse wave reference is not stable immediately after pressurization,
It is determined whether or not the baseline is stable (ST16), and the process waits until the baseline is stable. If the cuff pressure falls below 40 mmHg below the set value when the baseline is not stable (ST1
7), it is judged whether or not the re-pressurization has been already performed (ST
18) If the re-pressurization corresponds to the first time, set value +
With 30mmHg as the new setting value (ST19), the re-pressurization mark blinks (ST20), and the process returns to ST12,
When the pressure is re-pressurized to the set value, and the pressure is re-pressed to the re-set value, the determination of "whether it is the re-pressurizing process" in ST13 is YES,
The re-pressurization mark is turned off (ST14).

If re-pressurization has already been performed once, and if the current re-pressurization is the second time, the determination in ST18 is NO, the LED is turned off (ST31), and then the rapid exhaust valve 20 is opened to temporarily exhaust the gas. To do. When the baseline becomes stable until the cuff pressure decreases to the set value of -40 mmHg, the determination in ST16 is YES, and the amplitude of each pulse wave is measured in the subsequent processing. That is, the pulse number j for obtaining the amplitude of the pulse wave is set to 0 (ST21), and subsequently, the sample counter i within one night is set to 1, the pulse number is set to j = 1, and the maximum value xmax of the pulse wave level is set to 0. , The minimum value xm
Let in be xsup (ST22). Here, xsup is an upper limit value that the pulse wave level x _i can take.

Then, in ST23, it is determined whether the cuff pressure is larger than 20 mmHg. If less than 20mmHg, move to ST31,
Turn off the LED, return to ST3, and quickly exhaust valve 20.
Open the exhaust mark (ST4) and wait for exhaust, but if normal, the determination in ST23 will be YES, and then
The pulse wave data x _i is read (ST24), the difference value between the previous pulse wave data x _i-1 and the current pulse wave data x _i is calculated, and it is determined whether or not this difference value is larger than the predetermined value x _t. A judgment is made (ST25). This determination is made to make the pulse wave one beat at the point where the pulse wave level changes abruptly. That is, x _i-1 −x _i indicates the output of the pulse wave sensor 12, that is, the differential value of the pulse wave level, and the differential value x
_It is checked whether _i−1− x _i is larger than the threshold level x _t , and if it is larger, the determination in ST25 is YES and the pulse wave is detected.

If the determination in ST25 is NO, the process proceeds to the next ST32, it is determined whether or not the pulse number j is not updated for 1.5 seconds, and if it is updated, then the current pulse wave data x _i and the maximum pulse wave The magnitude relationship of the value xmax is compared (ST33). If x _i > x max, the current pulse wave data x _i is updated and stored as a new pulse wave maximum value x max (ST3).
4). On the other hand, if x _i ≦ xmax, ST34 is skipped and the process proceeds to ST35. In ST35, the magnitude relationship between the current pulse wave data x _i and the pulse wave minimum value x min is compared. If x _i <xmin, the current pulse wave data x _i is updated and stored as a new pulse wave minimum value xmin (ST3).
6). On the contrary, when x _i ≧ xmin, ST36 is skipped and the process proceeds to ST37.

When the updating of the maximum value xmax and the minimum value xmin of the pulse wave data is completed in ST33 to ST36, the counter i is updated in ST37.
+1 processing is performed, and the process returns to ST23. Thereafter, x
ST32 to ST37 until _i−1− x _i > x _t ,
By repeating the processing of ST23 to ST25, the maximum pulse wave value xmax
And the updating of the minimum value xmin is continued, and the maximum value xmax and the minimum value xmin of the pulse wave in the 1.5 second interval are obtained under the condition that x _i-1 −x _i corresponding to the differential value does not exceed the threshold level x _t. . These xmax and xmin will be used later in ST27.
Is used to calculate the pulse wave amplitude Aj in the 1.5 second interval.

When it is determined in ST25 that x _i-1 −x _i is equal to or more than the predetermined value x _t , the buzzer 25 is sounded in ST26, and the pulse wave extraction, that is, the presence of the pulse wave is notified. Then, the difference value Aj between the pulse wave maximum value xmax and the pulse wave minimum value xmin, that is, the pulse wave amplitude Aj is obtained (ST27). If the pulse number j has not been updated for 1.5 seconds in ST32, it is equivalently treated as one night has elapsed and the buzzer 25 does not sound, but the pulse wave amplitude Aj is obtained (ST2
7). The obtained pulse wave amplitude Aj is stored in the memory in the MPU 15.

The detection operation of the pulse wave amplitude Aj will be supplementarily described with reference to FIG.

The pulse wave data x _i detected in ST24 of the above flow, that is, the output of the pulse wave sensor 12 is continuously shown in a time system as shown in FIG. 4 (A). Further, x _i-1 −x _i in ST25 is a differential value because it is a change amount of the pulse wave level when it is shifted by one sampling period.
In ST25, this differential value x _i-1 −x _i is shown in FIG. 4 (B).
Is compared with the threshold level x _t shown in FIG. Then, as shown in FIG. 4 (C), x _i−1 −x _i > x _t
The pulse wave amplitude Aj is calculated at intervals of 1.5 seconds in the non-period (ST32, ST27), and the pulse wave amplitude Aj is calculated for each pulse wave (one beat) in the period of x _i-1 −x _i > x _t. (ST25, ST26, ST27). Therefore, the pulse wave amplitude Aj data can obtain not only the period in which the pulse wave in FIG. 4 (B) is detected but also the equivalent pulse wave amplitude Aj in other periods, which is necessary for blood pressure measurement. Much data is available.

Following the calculation of the pulse wave amplitude Aj in ST27, blood pressure determination processing is performed using this pulse wave amplitude Aj as a parameter (ST2
8) There are various algorithms for determining the blood pressure, but for example, the cuff pressure at the time when the pulse wave starts to appear is the maximum blood pressure P _SYS.
In addition, the cuff pressure at the time when the pulse wave amplitude (difference value) becomes maximum is the average blood pressure P _MEAN, and the minimum blood pressure P _DIA is P
_MEAN = calculated from _{P DIA + (P SYS -P DIA} ) / 3 expression. Then, ST22 is performed until the minimum blood pressure P _DIA is determined.
Then, in ST22, the pulse number j is incremented by 1, and then the above-mentioned processing is repeated, and the pulse wave amplitude Aj (maximum value x
A difference value between max and the minimum value xmin) is calculated, and the blood pressure determination process is continued.

When the process of determining the maximum blood pressure and the minimum blood pressure is completed (ST2
9), these blood pressure values are displayed on the display 24 (ST3
0) After that, the LED is turned off (ST31), the process returns to ST3, the quick exhaust valve 20 is operated, and the measurement operation is ended.

(F) Effect of the Invention According to the present invention, even when a part of the pulse wave cannot be detected,
Since the pulse wave amplitude is obtained with a pseudo pulse wave at regular intervals during that period, it is possible to obtain predetermined pulse wave amplitude data even when the amplitude of the pulse wave is small, or even when the pulse wave is gentle. Accurate blood pressure measurement can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of the present invention, FIG. 2 is a block diagram of a finger electronic blood pressure monitor in which the present invention is implemented, and FIG. 3 is a view for explaining an operation of the finger electronic blood pressure monitor. And FIG. 4 are time charts for explaining the operation of the electronic blood pressure monitor for the same finger. FIG. 4 (A) is a pulse wave component waveform, and FIG. 4 (B) is the same pulse wave. The differential waveform of the component, FIG. 4 (C) is a diagram showing the extracted pulse wave amplitude, FIG. 5 is a time chart for explaining the conventional example, and FIG. 5 (A) is the pulse wave component. FIG. 5B is a diagram showing a waveform, FIG. 5B is a differential waveform of the same pulse wave component, and FIG. 5C is a diagram showing an extracted pulse wave amplitude. DESCRIPTION OF SYMBOLS 1: Cuff, 2: Pressure system, 3: Cuff pressure sensor, 4: Pulse wave sensor, 5: Pulse wave presence / absence determining means, 6: First pulse wave amplitude detecting means, 7: Second pulse wave amplitude detecting means , 8: blood pressure determination means.

Claims (1)

[Claims] 1. A cuff for compressing an artery of a body to be measured, a pressure system for pressurizing or depressurizing the inside of the cuff, a cuff pressure sensor for detecting the pressure of the cuff, and a pulse wave in the process of pressure change of the cuff. A pulse wave sensor for detecting a component, a pulse wave presence / absence determining means for determining the presence / absence of a pulse wave by the pulse wave sensor output, and a pulse wave presence / absence determining means for determining the presence / absence of a pulse wave for each pulse wave The first pulse wave amplitude detecting means that uses the difference between the maximum value and the minimum value of the pulse wave sensor output as the pulse wave amplitude value, and the interval of a fixed time interval while the presence of the pulse wave is not determined by the pulse wave presence / absence determining means. Second pulse wave amplitude detection means for setting a difference between the maximum value and the minimum value of the pulse wave sensor output as a pulse wave amplitude value, a cuff pressure from the cuff pressure sensor, and the first and second pulse wave amplitudes. An electronic sphygmomanometer comprising blood pressure determining means for determining blood pressure based on the pulse wave amplitude from the detecting means.