JPH06113B2 - Electronic blood pressure monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention is based on cuff pressure detected by a pressure sensor and pulse wave information extracted from a pulse wave component detected by a pulse wave sensor. The present invention relates to an electronic blood pressure monitor that determines blood pressure.

(B) Conventional technology An electronic sphygmomanometer pressurizes a cuff worn around the finger with a pressurizing means, and then a pulse wave component such as the amplitude of the pulse wave is detected from the pulse wave component detected by the pulse wave sensor in the subsequent depressurization process. There is one that obtains wave information and determines blood pressure such as systolic blood pressure, mean blood pressure, diastolic blood pressure, etc. based on the pulse wave information and the cuff pressure detected by the pressure sensor.
In this type of electronic blood pressure monitor, there are various specific algorithms for determining blood pressure, but in the depressurization process after pressurization, the cuff pressure and the amplitude of the detected pulse wave are shown in, for example, FIG. When the pulse wave is detected,
That is, the cuff pressure corresponding to the point where the pulse wave amplitude exceeds the threshold value TH is the systolic blood pressure SYS, the cuff pressure corresponding to the point where the pulse wave amplitude is the peak is the average blood pressure MAP, and the systolic blood pressure and the average blood pressure ( 3MAP-SA
The minimum blood pressure DIA is calculated by calculating S) / 2.

In this electronic sphygmomanometer, strictly speaking, the systolic blood pressure is determined by determining whether the output of the pulse wave sensor, that is, the output of the pulse wave component exceeds a predetermined level after the start of measurement, or the gradient (change value) of the output. ) Has exceeded a predetermined value, and if the result of the determination is YES, the pulse wave is detected, the amplitude of the pulse wave is calculated, and if the amplitude exceeds the predetermined value, the corresponding cuff is detected. The pressure was the maximum blood pressure.

(C) Problems to be Solved by the Invention In the determination of the systolic blood pressure, the average blood pressure, the diastolic blood pressure, etc. according to the above-mentioned conventional technique, the output from the pulse wave sensor pressurizes or compresses the blood vessel to obstruct the blood flow, and then depressurize. It is premised that there are only vascular pulse waves generated in the process, but in the case of electronic blood pressure for fingers, if the measurer moves the finger, the pulse wave sensor outputs other than pulse waves. Unwanted waves (artifacts) in the input signal fluctuate and the output component fluctuates. Therefore, even though the pulse wave has not been detected yet, the artifact is erroneously detected as a pulse wave and the systolic blood pressure and average blood pressure are determined to be high values. However, there is a risk that incorrect measurement results may be obtained.

In view of the above, the present invention, even if an artifact occurs,
It is an object of the present invention to provide an electronic sphygmomanometer that can perform highly accurate measurement without being affected by it.

(D) Means and Actions for Solving Problems The electronic sphygmomanometer of the present invention has an artifact that occurs in a finger electronic sphygmomanometer or the like for a period corresponding to one to several pulse wave numbers at the beginning of measurement, After that, paying attention to the fact that there is more than one pulse wave period before the true pulse wave appears,
As shown in the schematic configuration in FIG. 1, a cuff 1 for compressing a blood vessel and a pressure system 2 for pressurizing / depressurizing the cuff.
A pressure sensor 3 for detecting the pressure of the cuff, a pulse wave detecting means 4 for detecting a pulse wave component from a blood vessel, and a pulse wave detecting means for detecting the pressure in the depressurizing process after pressurizing the cuff by the pressure system. In the blood pressure determining means 5 for determining the blood pressure based on the pulse wave information and the cuff pressure detected by the pressure sensor, the next pulse wave after the pulse wave is detected by the pulse wave detecting means. Time excess determination means 6 for determining whether or not the time until detection exceeds a predetermined time, and pulse wave information invalid processing means 7 for invalidating the pulse wave information detected up to that time by the output of this time excess determination means. And are characteristically provided.

In this electronic sphygmomanometer, when a pulse wave is detected by the pulse wave detecting means, it is further determined whether or not the time from that time point to the next pulse wave detection time point exceeds a predetermined value. The pulse wave up to is not a true pulse wave and is invalid.

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

FIG. 2 is an external perspective view of an electronic blood pressure monitor for a finger in which the present invention is implemented. The electronic blood pressure monitor for a finger is composed of a main body 11 and a cuff storage portion 12, which are connected by a cord wire 13. Are combined.

On the case surface of the main body 11, a display device 14 for displaying the maximum blood pressure, the minimum blood pressure, the pulse rate, etc., a pressurization value setting device 15 for selecting a pressurization setting value, a clear key 16, a start key 1
7, a power key 18 is provided.

In addition, a cuff rubber bag 19 having a cylindrical outer shape is stored in the case of the cuff storage portion 12. Although not shown, the cuff rubber bag 19 is provided with a pulse wave sensor for detecting a finger pulse wave. The electric signal line connecting the pulse wave sensor and the main body 11 and the cuff rubber bag 19 and the main body 11 are connected to each other. The rubber pipes connecting the two are bundled and connected as a cord wire 13 between them.

FIG. 3 shows a circuit block diagram of the electronic blood pressure monitor for the finger. In the figure, a pressurization value setting switch 15a, a clear switch 16a, a start switch 17a, and a power switch 18a correspond to the pressurization value setting device 15, the clear key 16, the start key 17, and the power key 18, respectively.
It turns on when these keys are operated. The ON / OFF signals and setting signals for these switches are
The data is input to the CPU 20.

The motor drive circuit 21 turns on / off the pump motor 22 in response to a command from the CPU 20. By starting the motor 22, the cuff rubber bag 19 is pressurized.

Further, the quick exhaust valve drive circuit 23 is configured to control the opening / closing of the valve 24 according to a command from the CPU.

By driving the motor 22, air pressure is supplied to the cuff rubber bag 19 through the air tank 25, and the pressure of the cuff rubber bag 19 is converted into an electric signal by the semiconductor pressure sensor 26 and passed through the amplifier circuit 27 to the A / D converter. It is adapted to be converted into a digital signal by the converter 28 and taken into the CPU 20.

Furthermore, the LED drive circuit 29 is responsive to a command from the CPU 20 to emit a light emitting element 30 attached to the cuff rubber bag 19.
On the other hand, the signal received by the light receiving element 31 is digitally converted by the A / D converter 28 via the filter 32 and the amplifier circuit 33, and is also taken into the CPU 20. In the light emitting element 30 and the light receiving element 31,
A pulse wave sensor is configured.

Display data from the CPU 20 is displayed on the display (LCD) 14 via the LCD drive circuit 34. In addition, the buzzer 36 is driven via the buzzer drive circuit 35 according to a command from the CPU 20. Reference numeral 37 is a slow exhaust valve.

The CPU 20 executes various functions according to the program of the flowchart described later, and the above-mentioned constituent circuits are the CPUs.
Under the control of 20, the blood pressure measurement operation is executed.

Next, the function of the CPU 20 and the operation of the finger electronic blood pressure monitor will be described with reference to the flowcharts shown in FIGS. 4 to 7.

<Overall Operation> First, the overall operation of the electronic blood pressure monitor for a finger will be described with reference to the flowchart in FIG.

When the power switch 18a is turned on, the operation starts,
All display patterns of the display (LCD) 14 are displayed,
[Step ST (hereinafter referred to as ST) 1] After that, all the display patterns of the display 14 are turned off, and it is checked whether the display 14 is operating normally (ST2). Then, the ready mark () is displayed on the display 14 (ST3). The measurer who sees this ready mark knows that the ready state for measurement has been reached, inserts his / her finger, for example, the index finger of the left hand into the cuff rubber bag 19, and then the start switch 17
Turn on a. When the start switch 17a is turned on, the determination in ST4 is YES, and then the preparation completion mark is turned off (ST5). Then, the pressure process is started.

Specifically, in the pressure treatment, first, the light emitting element 30 is turned on (S
T6), the valve 24 is closed (ST7), and the motor 22 for driving the pump is turned on (ST8). As a result, the cuff rubber bag 19 is pressurized via the air tank 25. Then, the pressurization is continued until the current pressure reaches the pressurization set value set by the pressurization value setter 15, and when the cuff pressure reaches the pressurization set value (ST9), the motor 22 is turned off (ST1).
0), pressurization is completed. After that, the air pressure of the cuff rubber bag 19 is gradually exhausted through the slow exhaust valve 37, and the measurement process starts.

In the measurement process, first, a pulse wave stability check is performed (ST11), and then a blood pressure determination process for the systolic blood pressure, average blood pressure, and diastolic blood pressure is performed (ST12). This processing is important for the present invention and will be described in detail later.

When the measurement is completed, the motor 22 is turned off (ST1
3), the valve 24 is opened (ST14), and the cuff rubber bag 1
The pressure of 9 is exhausted rapidly. When the current cuff pressure becomes 20 mmHg or less (ST15), the light emission of the light emitting element 30 is stopped (ST16), and the process returns to ST3 again to wait for the next measurement.

<Blood Pressure Determining Process> Next, details of the blood pressure determining process in ST12 will be described with reference to FIG.
This will be described with reference to FIGS. 6 and 7.

When the operation enters ST12 shown in FIG. 4, ST of FIG.
As shown in FIG. 21, first, AMP _-1 , AMP _-2 , AM
P _-3 , AMP _-4 , and AMP _-5 are set to 0, PLUS _{-H is set} to 0,
PLUS _{-L is set} to 5000. Where AMP _-1 , AMP
_-2 , ..., AMP _-5 is an area for memorizing the five pulse wave amplitudes in order from the present time. These pulse wave amplitudes are later used to determine a moving average of the pulse wave amplitudes to prevent the effects of pulse wave amplitude variations due to breathing.
PLUS- _H is an area for storing the maximum value of the pulse wave component, and PLUS- _L is an area for storing the minimum value of the pulse wave component. The pulse wave amplitude is obtained by calculating the difference between the maximum value and the minimum value of the pulse wave component.

After ST21, is the clear switch 16a on (S
T22), it is determined whether the current cuff pressure Cuff- _P is 20 mmHg or less (ST23). In a normal measurement in which the pressure is increased to a predetermined value, these are determined to be NO, and then it is determined whether AMP- _F is 0 (ST24). The AMP- _F is a flag whose pulse wave is 1 when the pulse wave is detected, that is, when the gradient of the output of the pulse wave sensor becomes equal to or more than a predetermined value by an interrupt process (not shown).

At the beginning of measurement, AMP- _F is 0, so next ST2
In 5, ST26 and ST27, the current (cuff) pressure is displayed on the diastolic blood pressure display section of the display 14 every time the timer T _-1 measures 500 milliseconds, that is, every 0.5 seconds, and the procedure returns to ST22 except for the display timing. , ST22, ST23, ST24 are repeated.

When the pulse wave is detected and AMP- _F becomes 1, the determination in ST24 becomes YES, the process proceeds to ST28, AMP- _{F is set} to 0, and it is determined whether the AMP- ₁ pulse wave is 100 or less (ST2
9), if 100 or less, jump to ST31 and vice versa
If AMP _-1 exceeds 100, it is determined whether or not the previous pulse wave amplitude AMP _-2 is 100 or more (ST30), and AM
If the pulse wave amplitude of P _-2 is not 100 or more, it means that the pulse wave amplitude this time exceeded 100 for the first time, and again ST
Move to 31.

In ST31, the timer T _-BUZ is set to 200 milliseconds, the timer T _-1 is set to 1.5 seconds, the symbol of the display 14 is turned on, and the minimum blood pressure display section displays the cuff pressure at the time of the current pulse wave detection. Display Cuff _-0 . Then, the cuff pressure Cuff- ₀ is provisionally registered as the systolic blood pressure SY.

Subsequently, it is determined whether or not the clear switch is on (ST32) and whether or not the current cuff pressure Cuff- _P is 20 mmHg or less (ST33). In the normal measurement after being pressurized to the predetermined value, the clear switch 16a is not turned on, and the cuff pressure is not reduced to 20 mmHg or less. Therefore, these determinations are NO, and the process proceeds to ST34. It is determined whether or not the timer T _-1 is 0. That is, it is determined whether or not 1.5 seconds have passed since the previous pulse wave detection. When the timer T _-1 is 0, that is, when the next pulse wave is not yet detected (time excess determination means), it is determined whether the timer- _BUZ has reached 3 (ST3
6) If the timer T- _BUZ is 4 or more, return to ST32,
When it reaches 3, the timer T- _BUZ is _set to 0 and the symbol is turned off. As a result, the symbol is displayed for about 200 milliseconds (ST37).

When the next pulse wave is detected before the timer T _-1 has timed up to 0 and AMP _-F = 1 is set, the determination at ST35 becomes NO and the process returns to ST28. Then, after setting AMP _-F to 0, it is determined whether or not the new AMP _-1 is 100 or less. If it is 100 or less, the process proceeds to ST31, and the cuff pressure Cuff _-0 at the time of detecting the current pulse wave is set to the maximum. If the AMP _-1 exceeds 100 and the previous pulse wave amplitude AMP _-2 is 100 or more, it is temporarily registered again as hypertension SYS, but ST3
Go to 8.

In ST35, the timer T _-1 = 0 in ST34 until the determination of AMP _-F = 0 becomes NO, that is, the next pulse wave is detected, and 1.5 seconds have passed since the previous pulse wave detection. After the passage of time, it is assumed that the previous pulse wave is an abnormal wave due to artifacts, and this is invalidated.
Then, the reprocessing is started (pulse wave information invalid processing means). Then, the process proceeds to ST31 in the reprocessing process, and the cuff pressure Cuff- ₀ at the time of detecting a new current pulse wave is provisionally registered as SYS.

Next, the process of determining the temporarily registered SYS will be described.

In ST38, AMP- _{C is set} to 3. This AMP- _C is
It is a pulse wave counter that is counted in connection with the detection of a pulse wave, and is used to determine the temporary SYS as the SYS when the pulse wave appears three times in a row after the temporary SYS is registered. To be done.

Following ST38, AMP- _{F is set} to 0 and AMP
_-C is decremented by 1 (ST39), then the content of AMP _-C is 0
It is determined whether or not (ST40). AMP _-C = 3 in ST38
At the beginning, since AMP _-C = 2 in ST39, this determination is NO, and then the timer T _-1 is set for 1.5 seconds, and the buzzer beep is emitted for 200 milliseconds. The symbol is illuminated. And after that,
In ST42 to ST47, the same processing as ST32 to ST37 described above is executed. That is, the next pulse wave is detected by the time the timer T _-1 times up, and AMP _-F becomes 1
Then, the process returns to ST38, the AMP- _{C is} further decremented by 1 in ST39, and the pulse wave detection process is continued as it is.
By the time the timer T _-1 expires, that is, even if 1.5 seconds have passed since the previous pulse wave was detected (time excess determination means),
If the next pulse wave is not detected, the pulse wave up to that point is an abnormal wave and is invalidated (pulse wave information invalid processing means).
The process returns from ST44 to ST21.

When the next pulse wave appears within 1.5 seconds after setting AMP- _C to 3 in ST38, "AMP- _C = 0 in ST40"
The judgment "YES" is YES, and the temporarily registered SYS is displayed on the systolic blood pressure display section of the display unit 14 (ST4
8).

When the systolic blood pressure is determined, the processing shown in FIG. 6 is performed next.

First, in ST49, AMP _-MX, the Cuff _-T to 0. Here, AMP- _MX is a storage area for obtaining a moving average of five pulse wave amplitudes, and is an area for storing the sum of five pulse wave amplitudes, and Cuff- _T is a pulse wave amplitude later. It is an area for storing a cuff pressure lower by 10 mmHg from the peak point of.

After ST49, the timer T _-1 is set to 1.5 seconds (ST50). The 1.5 seconds of the timer T _-1 is for judging that an error occurs because the interval is too long when 1.5 seconds or more elapses from one pulse wave to the next pulse wave, as in ST31. .

Next, AMP _-MX becomes AMP _-1 + AMP _-2 + AMP _-3 + A
It is determined whether or not MP _-4 + AMP _-5 or less (ST5
1). This determination compares the magnitude relationship between the sum of the five pulse wave amplitudes and the pulse wave amplitude already stored in the AMP- _MX . To obtain the moving average from the five pulse wave amplitude data before the current time, AMP _-1 + ... +
Although AMP- ₅ will be further divided by 5, if AMP- _MX is also not divided by 5, the comparison judgment is the same, so division by 5 is omitted. When the pulse wave amplitude is in the process of rising, the determination is YES, and then the process proceeds to ST52, where the current AMP _-1 + ... + AMP _-5 is stored in AMP _-MX ,
The third cuff pressure Cuff _-3 (AMP _-1 , AM
Corresponding to P _-2 , ..., AMP _-5 , the corresponding cuff pressure is also C
It is stored in uff _-1 , Cuff _-2 , Cuff _-3 , Cuff _-4 , and Cuff _-5 . In addition, Cuff- ₀ stores the cuff pressure at the time of detecting the current pulse wave following Cuff- ₁ ) is stored in the average blood pressure MAP, and Cuff- _T stores the cuff pressure at the time of detecting the current pulse wave Cuff- ₀ to 10 mmHg.
Memorize the cuff pressure that has been reduced. This is 1 from the peak
The cuff pressure is 0 mmHg lower, and is used to judge a constant cuff pressure drop. Also, 2 is stored in AMP- _C .

Next, in ST53, a symbol is displayed, a buzzer called Beep is sounded for 200 milliseconds, and the cuff pressure Cuff- ₀ at the time of detecting the current pulse wave is displayed on the diastolic blood pressure display portion. Then, it is determined whether the clear switch 16a is turned on (ST
54). Normally, when the clear switch 16a is not turned on, this determination is NO, and it is further determined whether the timer buzzer T _-BUZ is 0 (ST55). When the timer buzzer T _-BUZ set to 200 milliseconds has not timed up, it waits for 200 milliseconds here, and when the timer buzzer T _-BUZ times up, the symbol is subsequently turned off (ST56), and now It is determined whether or not the cuff pressure Cuff _-P is less than 20 mmHg (ST57), and further it is determined whether or not the timer T _-1 is up to 0 (ST5).
8). At this point, the cuff pressure becomes 20 mmHg or the timer T
_{If -1} has timed up and the pulse wave does not arrive for 1.5 seconds, it is determined that there is an error, and the process proceeds to ST71.

On the other hand, in ST57, when the cuff pressure Cuff- _P is not less than 20 mmHg and the timer T _-1 is not 0, that is, 1.5 seconds have not elapsed, the clear switch 16a is not turned on yet (ST59), Furthermore, if AMP _-F is 0 (ST60), until AMP _-F becomes 1, the AMP _-F i.e. the check of the pulse wave traveling in a different interrupt processing 1
The processing of ST57 to ST60 is repeated until
When the timer T _-1 does not further time up to 20 mmHg or less and AMP _-F becomes 1 within 1.5 seconds, that is, when the pulse wave amplitude is detected, AMP _{-F is set} to 0 in ST61. , {H _B + (150 + T ₋₁ )} / 2 as new H _B
Then, the process for pulse detection is performed, and the process returns to ST50.

While the pulse wave amplitude detected this time is larger than the previous time, ST
The determination in step 51 is YES, and the above-described processing proceeds, but when the pulse wave amplitude passes the peak point and starts to fall, ST5
1 of the determination is NO, followed by a decreased 1 from AMP _-C and is stored as a new AMP _-C (ST6
2). Already since 2 AMP _-C is set, the times will be 1 is stored in the AMP _-C. Therefore, S
The judgment of "Amp _-C ≥ ₀ " at T63 is YES,
The process jumps to ST53, and the same processing as the previous time proceeds.

At the next stage, when the pulse wave amplitude starts to fall and the second pulse wave amplitude is obtained, the determination in ST51 also becomes NO, the processing of AMP- _C- 1 is performed in ST62, and a new AMP- _C is stored again. Since AMP- _C is 1 at this point, the newly stored AMP- _C becomes 0, the determination in ST63 is still YES, and the process jumps to ST53, where the series from ST53 to ST61 is the same as the previous / previous two times. Will be continued. And it returns to ST50 again and ST51
Then, the third moving average value after it starts to fall is also NO. In this case, -1 is counted as AMP _-C in ST62, so the determination in ST63 is NO.
Then, at this third time, the process first moves to ST64, where it is further judged whether "Cuff _-0 ≥ Cuff _-T ", and the current cuff pressure Cuff _-0 is set at 10 mmHg lower than the peak cuff pressure Cuff. _-Determine if it is greater than _T. If the cuff pressure Cuff _-0 at the time of detecting the current pulse wave is still larger,
The maximum value of the pulse wave amplitude up to that point is not yet determined as the peak value, the process proceeds to ST53, and the same process as the previous time is performed. For example, even though the pulse wave cycle is very fast and all three pulse wave detections tend to drop, it is dangerous to judge that the peak point is a true peak point when the cuff pressure hardly drops. Therefore, such processing will be performed.

However, if Cuff- ₀ becomes smaller than Cuff- _T in ST64, it means that the cuff pressure itself has dropped considerably in three pulse wave amplitude detections.
At 65 (see FIG. 7), the cuff pressure corresponding to the peak value of the pulse wave amplitude up to that point is determined as the average blood pressure MAP, and the minimum blood pressure DIA is determined from the average blood pressure MAP and the maximum blood pressure SYS. Calculate from the following formula.

Then, this minimum blood pressure DIA is displayed on the minimum blood pressure display section.

Thereafter, those were single split 6000 in _{H B} was stored in _{H B} (ST66), or the _{H B} over 200 (ST67),
Alternatively, it is checked whether it is 40 or less (ST68), and if any judgment is YES, error processing (ST71) is performed, but when H _B is less than 200 and 40 or more, the pulse rate is within the normal range, Make a beep sound for 1 second (S
(T69), move to ST13 and perform exhaust treatment.

In addition, ST22, ST32, ST42, ST54, ST
When the clear switch 16a is turned on at each stage of 59, the storage area H _{B is set} to 0, the systolic blood pressure display section is turned off (ST70), and after ST69, S of FIG.
It jumps to T13 and starts exhaust processing.

In ST23, ST33, ST43, and ST58, if the current cuff pressure Cuff- _P is less than 20 mmHg, ST71
Then, while H _{B is set} to 0, Er is displayed, a beeping sound is emitted for 2 seconds, and an error is reported.
Moving to ST13, exhaust processing is started.

(F) Effect of the Invention According to the present invention, when a pulse wave is detected and a predetermined time or more elapses before the next pulse wave is detected, the pulse wave detected up to that point is invalidated and the subsequent pulse wave is detected. Since the detection is continued, even if an abnormal wave due to an artifact is mixed, its influence can be removed, and highly 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 an external perspective view of an electronic blood pressure monitor for a finger according to the present invention, and FIG.
The figure is a circuit block diagram of the electronic blood pressure monitor for the same finger.
An overall flowchart for explaining the operation of the electronic blood pressure monitor for the finger, FIGS. 5 and 6 are flowcharts showing the blood pressure determination processing routine of the overall flowchart in more detail, and FIG. 8 is a cuff pressure. It is a figure which shows a change and a pulse wave amplitude change. 1: Cuff, 2: Pressure system, 3: Pressure sensor, 4: Pulse wave detection means, 5: Blood pressure determination means, 6: Time over discrimination means, 7: Pulse wave information invalid processing means.

Claims (1)

[Claims] 1. A cuff for compressing a blood vessel, a pressure system for pressurizing / depressurizing the cuff, a pressure sensor for detecting the pressure of the cuff, and a pulse wave detection for detecting a pulse wave component from the blood vessel. Means for determining blood pressure based on the pulse wave information detected by the pulse wave detection means and the cuff pressure detected by the pressure sensor in the depressurizing process after pressurizing the cuff by the pressure system. In an electronic sphygmomanometer including means, a time excess determination means for determining whether or not the time from the detection of a pulse wave by the pulse wave detection means to the next pulse wave detection exceeds a predetermined time, and the time excess determination means An electronic sphygmomanometer including pulse wave information invalidation processing means for invalidating the pulse wave information detected so far by the output of 1.