JPS63286135A - Electronic hemomanometer - Google Patents

Abstract

PURPOSE:To realize the miniaturization of a meter while making it possible not only to detect and remove an abnormal pulse wave but also to smooth a pulse wave envelope by a simple means, by mounting a pulse wave envelope smoothing means setting the value other than the max. and min. values among an odd number of pulse wave amplitude data, to which median filter processing is applied, to a median value. CONSTITUTION:A CPU 9 takes in the output signal, which is converted to a digital value by an A/D converter 7, of a pressure sensor 5 at a definite cycle. A band-pass filter 8 extracts the pulse wave component appearing on a cuff pressure signal and the CPU 9 takes in this pulse wave signal. The CPU 9 calculates a pulse wave amplitude value to determine the min. blood pressure value and the max. blood pressure value from the obtained pulse wave amplitude and cuff pressure values and applies median filter processing to an odd number of the obtained pulse wave amplitude data to realize the detection and removal of an abnormal pulse wave and the smoothing of the envelope of pule wave amplitude. By this method, the abnormally large amplitude value (due to body motion or arm motion) in a pulse wave amplitude train is removed and substituted with an amplitude value estimated in usual manner.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention is a vibration method electronic blood pressure monitor, which detects and removes Tatsumi ordinary pulse wave amplitude and smooths the pulse wave envelope line. Regarding electronic blood pressure monitors.

(b) Conventional technology The vibration method electronic blood pressure monitor detects the DC component of the cuff pressure signal during the slow evacuation stage after pressurizing the cuff, and extracts the pulse wave component contained in the cuff pressure signal. .

For example, find the maximum amplitude for each beat of this pulse wave line segment, and use this maximum pulse wave as a parameter to create a time series (or cuff pressure series).
Arrange it to get the envelope line. Then, the blood pressure value is determined from this envelope and the cuff pressure DC. The algorithm for determining blood pressure is, for example, the cuff pressure corresponding to the maximum value point of a parameter (envelope line) is the average blood pressure, the cuff pressure on the high pressure side corresponding to the parameter corresponding to 50% of the maximum value point is the systolic blood pressure, and the maximum value is The cuff pressure on the low pressure side corresponding to the parameter corresponding to 70% of the points is determined to be the diastolic blood pressure.

By the way, in a vibrating electronic blood pressure monitor, if the pressure sensor is in a normal position relative to the upper chamber, and this normal position is maintained, a normal variation (normal parameter distribution corresponding to cuff pressure changes) will occur. However, if artifacts (artificial products) such as arm movement or body movement occur during measurement, the variation distribution becomes abnormal, and the blood pressure is determined by applying the normal algorithm, and the measurement results are not correct. This will result in a large error.

Therefore, conventionally, due to artifacts (body movements),
If an abnormality occurs in the pulse wave amplitude distribution, an abnormality detection means that compares the pulse wave amplitude sequences and the difference value between the pulse wave amplitude value sequences is used, and an algorithm is applied by ignoring the abnormal amplitude value. In order to perform blood pressure measurement or to smooth the envelope drawn by the pulse wave amplitude value sequence, smoothing processing such as moving average processing is performed on the pulse wave amplitude value sequence. A method has been adopted in which blood pressure determination logic (algorithm) is applied to the smoothed envelope to perform blood pressure measurement.

(c) Problems to be Solved by the Invention" According to the conventionally adopted methods, it is possible to detect and detect abnormal pulse wave amplitude by each means (abnormality detection means or envelope smoothing cuff means). Subtraction and envelope smoothing operations may be accomplished.

However, the former method requires calculation means such as comparing pulse wave amplitude sequences and comparing difference values between pulse wave amplitude value sequences, whereas the latter method is a method of calculating the moving average value of the pulse wave amplitude value sequence. can be,
In either method, since the calculation means is a double controller, there is a disadvantage that the processing time is long. Moreover, these calculation means are performed by separate means, that is, the abnormal pulse wave detection means and the pulse wave envelope smoothing means are achieved by separate means. Therefore, if these functions are combined with functions other than the abnormal pulse wave detection means and the pulse wave envelope smoothing means, the means will become even more complicated, and there will be disadvantages such as not being able to achieve miniaturization. was there.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic sphygmomanometer that can detect and remove abnormal pulse waves and smooth the pulse wave envelope line simultaneously by simple means, and that can realize miniaturization of the instrument.

(d) Means and operation for solving the problem In order to achieve this object, the electronic blood pressure monitor of the present invention has the following configuration.

The electronic blood pressure monitor includes a cuff, a pressurizing means for pressurizing the cuff, a depressurizing means for reducing the pressure inside the cuff, a pressure horn detecting means for detecting the fluid pressure inside the cuff, and an output signal of the pressure detecting means. pulse wave component detection means for detecting a pulse wave component included in the pulse wave component; pulse wave amplitude value calculation means for calculating a pulse wave amplitude value from the pulse wave component detected by the pulse wave component detection means; and blood pressure value determining means for determining a systolic blood pressure value and a diastolic blood pressure value based on the output signal of the calculating means and the output signal of the pressure detecting means, the electronic blood pressure monitor comprising: The method is characterized in that it performs median filter processing on the odd number of pulse wave amplitude data, and uses a value that is neither the maximum value nor the minimum value among the odd number of pulse wave amplitude data as the median value. We are prepared.

In an electronic blood pressure monitor having such a configuration, a smoothing means is applied to a plurality of (odd number) obtained pulse wave amplitude sequences. The smoothing means uses a median filter. That is, every time an odd number (for example, +, +: 3) pulse wave amplitude sequences are obtained, the median filter is applied to these three numerical value (pulse wave amplitude value) sequences. Here, the median filter is a numerical value sequence obtained as shown in Fig. 2, for example, ra (
n), a(n-1-1), aCn+2)], then this numerical sequence is converted into (b (n), b
(n-1), b('n-2)). Here, the fixed rules are a (n), a (
n-1) and a(n2), which is neither the maximum value nor the minimum value, is set as me (median value). Also, if there are two maximum values in three numerical sequences, then for one column, a (n) = a (n+1) > a
(n-1-2), the minimum value is mP, and b
(n) -a(n), b(n-1-1) = m,,
, b (n+2) = a (ni-2). In other words, b (n)≦b(nt-1)≦b(n-
1-2), or b(n-1-2)≦b(n-1
-1)≦b(n).

The smoothing process by this median filter is performed using an odd number (
Each time a pulse wave amplitude sequence (3) is obtained, a median filter is applied to these three numerical value sequences. As a result, as shown in Figure 5, if an abnormally large amplitude value (abnormal amplitude value due to body movement, arm movement, etc.) exists in the pulse wave amplitude sequence that is expected to be normally obtained, this large amplitude The value is removed by applying a median filter and replaced by the normally expected amplitude value. Therefore, an odd number of pulse wave amplitudes (amplitude number sequence)
By passing the signal through a melodian filter, it becomes possible to detect and remove abnormal amplitude and smooth the pulse wave envelope simultaneously with one means.

(E) Embodiment FIG. 3 is a block diagram showing a specific embodiment of the air system and measurement circuit of the electronic blood pressure monitor according to the present invention.

A pressurizing pump (pressurizing means) 4, an exhaust valve (exhausting means) 3, and a pressure sensor (pressure detecting means) 5 are connected to the cafe via a tube 2.

The exhaust valve 3 is composed of two types of valves: a rapid exhaust valve and a slow exhaust valve. Further, the pressure sensor 5 uses, for example, a diaphragm transducer using a strain gauge. The pressurizing pump 4 and the exhaust valve 3 are connected to a CPU which will be described later.
(Central Processing Unit) 9.

The output signal (analog quantity) of the pressure sensor 5 is amplified by an amplifier 6 and converted into a digital value by an A'/D converter 7. The CPU 9 takes in the output signal of the pressure sensor 5, which is converted into a digital value by the A/D converter 7, at regular intervals. Further, the output signal of the pressure sensor 5 is passed through an amplifier 6 to a band pass filter 8.
Then, the pulse wave component appearing on the cuff pressure signal is extracted, and the CPU 9 takes in this pulse wave signal (pulse wave component).

C, P U 9 has a function of calculating a pulse wave amplitude value and a function of determining a diastolic blood pressure value and a systolic blood pressure value from the rubbed pulse amplitude value and cuff pressure value. The CPU 9 also stores the obtained odd number (for example, three) pulse wave amplitude data (pulse wave amplitude string).
It has the function of performing median filter processing on the pulse waves, detecting and removing abnormal pulse waves, and smoothing the envelope of pulse and wave amplitudes. Here, median filter processing refers to an odd number (
For example, each time a series of pulse wave amplitudes (for example, three) is obtained, a median filter is applied to the series of three numerical values (pulse wave amplitude values). Here, the median filter is a numerical value string obtained as shown in FIG. 2, for example, [a(n), a(n+1
), a (n +2) ), then this numerical sequence is 1 □
According to the given rules, (b(n'), b(n+1),
b(n+2)]. Here, the fixed rules are a (n), a (n+1), a'
The value of (n+2) that is neither the maximum value nor the minimum value (in the example of FIG. 2, a(n+2)) is set as me (median value). In other words, by applying median filter processing to these three number sequences, □, a (n) becomes b (
n), and a(n+1) changes to b(nt1). That is, b(n+1) here means a(n+2). The rule is that a(n+2) changes to b(n+2). Also, if there are two maximum values in three numerical sequences, for example, a (n) = a (n+ 1) > a
(n+2), in this case the minimum value is mQ (median (direct), b(n) = a(
n) ,b(n+1)=m, ,b'(n+2)'=
It is to replace it with a(n+'2).

In other words, b (n) ≦b (n+1) ≦ b (n+2)
, or a rule that sets the relationship b(n+2)≦b(n+1)≦b(n').

The smoothing process by this median filter is performed using an odd number (
Each time three (3) pulse wave amplitude sequences are obtained, median filter processing is applied to the three numerical value sequences in sequence. As a result, as shown in Figure 5, if an abnormally large amplitude value (abnormal amplitude value due to body movement, arm movement, etc.) exists in the pulse wave amplitude sequence that is expected to be normally obtained, this large amplitude The value is removed by applying a median filter and replaced by the normally expected amplitude value. Therefore, by passing an odd number of pulse wave amplitudes (amplitude number sequence) through a melodian filter, it is possible to detect and remove abnormal amplitudes and smooth the pulse wave envelope simultaneously with one means.

Furthermore, the CPU 9 displays the systolic blood pressure value and the diastolic blood pressure value on the display 1.
It has a function to display 0.

FIG. 4 is a flowchart showing specific processing operations of the electronic blood pressure monitor according to the embodiment.

When the operation starts, the pressurization pump 4 is driven by a signal from the CPU 9, and pressurization of the cuff 1 is started [step (
(hereinafter referred to as rsTJ)■]. When the cuff pressure reaches a predetermined value due to this pressurization, the CPU 9 recognizes that the cuff pressure has reached the set value (5T2), stops the pressurization pump 4 (Sr1), and ends the pressurization. After this, the exhaust valve 3 starts exhausting at a slow speed according to a signal from the CPU 9 (5T4)
, the process moves to the following blood pressure determination process.

First, variables n and Hmax are each initialized to O (
Sr1). Here, the variable n is a pulse wave counter that is incremented every time the CPU 9 recognizes one pulse wave,
Hmax is a variable that holds the maximum pulse amplitude value in order to recognize the maximum pulse wave amplitude value.

Next, set the variable i, Pmax and Pm1n to O
(Sr1). Here, j is CPU9 A/
It is a counter for cuff pressure data A (+) and pulse wave data P (i) read from the D converter 7, and Pmax, Pm
1n is a variable that holds the maximum value and minimum value of the pulse wave, respectively, in order to calculate the pulse wave amplitude value for each beat.

Furthermore, after that, increment the variable n by 1 (5T7)
, i is also incremented (Sr8), pulse wave data P
(i) is read from the A/D converter 7.

Then, the value of this pulse wave data P(t) is compared with Pmax (5TIO), and if P(i) is larger than Pmax, the value of P(i) is substituted into Pmax at 5TII and P After updating the maxO value, proceed to the next step 5T12. However, in other cases, directly from 5TIO, 5
Move to T12.

In 5T12, P(i) is compared with Pm1n, and P(i)
If the value of is smaller than Pm1n, the value of P(i) is assigned to Pmin in 5T13, Pm1n is updated, and then the process moves to 5T14. However, in other cases 5
Transition directly from T12 to 5T14.

At 5T14, a break point of the pulse wave data is detected and it is determined whether it is one or more. Here, a breakpoint is a point at which the pulse wave data P (i) is at a certain threshold level (reference line).
This is the point where the pulse wave intersects in the rising process, and it gives a break between each beat of the pulse wave.

If the pulse wave breakpoint is detected, proceed to the next 5T15, but if not detected, proceed to S for the next pulse wave data.
Repeat the processes from r8 to 5T14.

Now, if the breakpoint of the pulse wave is detected, Pmax and P
m1n, and calculate this difference value as the pulse wave amplitude value G (n
) (ST15).

Here, a median filter is applied to the sequence of G (n) (pulse wave amplitude value sequence) which is the main part of this invention, but unless n≧3, that is, the number n of pulse wave amplitudes obtained is 3 or It cannot be applied unless there are an odd number of 3 or more. Therefore, 5T16
Then, it is determined whether three or more pulse wave amplitude numbers n are detected, that is, whether median filter processing can be applied. If the number n of pulse wave amplitudes is 3 or less, '
The determination in S T 16 is NO, and the subsequent median filtering process of 5T17 is not performed, and the process skips to 5T1B. Conversely, if the pulse wave amplitude number n is 3, 5T1
6 is YES, and in 5T17, a melodian filter process, which will be described later, is performed, and the result is set as H(n), and a pulse wave envelope smoothing process is performed.

Then, the cuff pressure data is read from the A/D conversion RF, 7, and the cuff pressure 4Fi, A corresponding to the pulse wave amplitude value G (n) is read.
(n) (STlB).

In the next 5TI9, the pulse wave amplitude 4fi H(n) is Hma
It is determined whether or not it is larger than x. H(n) is Hma
If it is larger than After assigning and storing, Sr1
The process returns to step Sr1 to Sr1 to 5T20 for the next pulse wave amplitude value. If the pulse wave amplitude value has not yet reached the maximum pulse wave amplitude point and is in the upper bound process, H(n) is always greater than Hmax, so this process is repeated.

Now, assuming that the pulse wave amplitude value H(n) has become smaller than Hmax, the determination in 5T19 is No, and in 6ST21, which moves to ST21, the pulse wave amplitude value H(n) is 0.7 H.
It is determined whether or not it is smaller than max.

That is, it is determined whether the pulse wave amplitude value has passed the maximum pulse wave amplitude point and entered a downward process, and has reached 70% of the maximum pulse wave amplitude value N value. Here, the pulse wave amplitude value that is 70% of the maximum pulse wave amplitude value refers to the cuff pressure that is set as the diastolic blood pressure value.

If the pulse wave amplitude value is greater than 70% of the maximum pulse wave amplitude value, the determination in Sr11 becomes No, the process returns to Sr1, and the processes from Sr7 to Sr11 are repeated. Now, if the pulse wave amplitude value is 70% of the maximum pulse wave amplitude value, Sr
11 becomes YES, and the cuff pressure A (n
) is the diastolic blood pressure value (Sr22). After this, 5T23
The systolic blood pressure value is determined, for example, the cuff pressure corresponding to the pulse wave amplitude value corresponding to 50% in the rising process of the maximum pulse wave amplitude value is determined as the maximum surface pressure value, and the cuff 1 is rapidly evacuated (5T24). The systolic blood pressure value and the diastolic blood pressure value are displayed on the display 10 (5T25), and the measurement is completed.

FIG. 1 is a main flowchart showing a specific processing operation of the median filter processing executed at 5T17 of the main flow (FIG. 4).

This median filter processing consists of a process to find the maximum value of three numbers 4Fi (pulse wave amplitude values) G(n), G(n-1), G(n-2), a process to find the minimum value, and a median filter. The process of calculating the value, and the median value (result value)
(n). Further, G1, G2, and G3 used in this flowchart are variables that store the maximum value, median value, and minimum value, respectively.

Median filter processing first begins with Sr11 to 5T3.
5 and three numbers, G (n), G (n-1), G(
Find the maximum value of n-2). In Sr11, G(n
) is the maximum value (hereinafter referred to as "G1").

In Sr12, this maximum value Gl [Here, G1 is G(n)] and G(n-1) are compared, and G1 is C(n-1).
1) Determining whether it is smaller than Now, assuming that 01 is smaller, the determination of Sr12 becomes YES, and in the next 5T33, G(n 1) is updated to Gl.

Conversely, if 01 is larger than G(n-1), Sr12
The determination becomes NO, and the process moves to Sr14. In 5T34, G1 is compared with G(n-2), and G1 is C,(n-2).
2) Determining whether the value is smaller than the value. If G1 is smaller, the determination of 5T34 will be YES, and the next 5T3
5, change C(n-2) to Gl. Conversely, if G1 is larger than G(n-2), the determination for Sr14 is NO.
Then, the process moves to 5T36. As a result of this series of processing,
Gl has three numbers, G (n), G (n-1),
The maximum value of G(n 2) is stored (corresponds to a(n+1) in FIG. 2).

Next, three numerical values G (n) from 5T36 to Sr10,
Find the minimum value of G(n-1) and G(n2). 5T
In 36, it is assumed that G (n) is the minimum value (hereinafter referred to as rG3.l).

For Sr17, the minimum value G3 [here, G3 is G(n)
) and G(n=1) to determine whether G3 is larger than G(n 1). Suppose that G3 is G(n
-1), the judgment of this 5T37 is YE
S, G31 is applied to G(n-1) (ST3B). Conversely, if G3 is smaller than G(n 1), the determination at 5T3B is No, and the process moves to Sr19. In Sr19,
Compare G3 and G(n-2), G3 is G(n 2)
It is determined whether the

If G3 is larger than G(n-2), then 5T3
9 becomes YES and G'(n-2) is set to 63 (Sr40). Conversely, if G3 is smaller than G(n-2), the judgment of Sr19 becomes No and the process moves to 5T41. As a result of this series of processing, G3 has three numbers,
The minimum value of G, (n), G (n-1), and G (++-2) is stored [corresponds to a (n) in FIG. 2]. After this, processing for calculating the median value is started using Sr11 to Sr17.

In Sr11, it is determined whether G (n) is not larger than Gl (maximum value), and in 5T42, G (n) is determined to be G3 (
It is determined whether the value is smaller than the minimum value). That is, it is determined by Sr11 and Sr12 whether G(n) is the median value (hereinafter referred to as "G2"). If G (n) is 61 or less and 03 or more, the determinations of both Sr11 and S T 42 become YES, and G (n) is stored as a median value in G2 (Sr1, 3). This corresponds to a(n+2) in FIG. Then, let this G2 be H(n) in Sr1 B. However, if G (n) is not 02, that is,
If the condition of G2 is not satisfied (the condition of being smaller than Gl and larger than G3), the determination of Sr11 or 5T42 becomes NO, and the process moves to Sr14.

In Sr14, it is determined whether G(n 1) is not larger than 01, and in Sr15, it is determined whether C, (n-1) is not smaller than 63. In other words, Sr1.4
and Sr15, it is determined whether G(n-1) is 62 or not. If G(n-1) is 61 or less and G3 or more, the determinations of Sr14 and Sr15 are both YES, and G(n-1) is adopted as 02 and stored (Sr46).

However, if G(n-1) does not satisfy the condition 62,
That is, if G(n-1) is greater than 61 or smaller than G3, the determination of Sr14 or Sr15 is NO, and G(n) is determined to be G2 (Sr47). In this way, the determined (adopted) G2 is stored in H(n) (
ST4B).

The above median filter processing is performed sequentially for every three p number sequences. As a result, as shown in FIG. 5, in the first process (A), three pulse wave amplitude values ■■■ are processed, and ■' is obtained, and in the second process (13), three pulse wave amplitude values are obtained. Median filter processing is performed on the pulse wave amplitude values ■°■■, and ■゛ is obtained. Furthermore, the third treatment (C
) is executed for three pulse wave amplitude values ■“■■, and ■°
is obtained. In this way, similar processing is repeated one after another. In this way, a smoothed pulse wave envelope is obtained.

Therefore, an abnormal pulse wave amplitude is detected and corrected at the same time, and a smoothed pulse wave envelope line is obtained.

(f) Effects of the Invention In the present invention, as described above, by performing median filter processing for each odd number of pulse wave amplitude values, it is possible to obtain a smoothed envelope of the pulse wave amplitude.

Therefore, detection and removal of abnormal pulse wave amplitude and smoothing of the envelope line can be simultaneously realized by a single envelope smoothing means called a median filter.

Therefore, the complicated calculation means required to detect the abnormal pulse wave amplitude as in the past is unnecessary, and correction of the abnormal pulse wave amplitude and smoothing of the envelope can be achieved simply and with a single means. This invention not only meets the demand for miniaturization of instruments, but also has excellent effects in achieving the purpose of the invention, such as eliminating disadvantages such as stopping measurement due to detection of abnormal pulse wave amplitude as in the prior art.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the main parts of a specific processing operation for calculating the median value of the electronic blood pressure monitor according to the embodiment, and Fig. 2 shows how odd-numbered pulse wave amplitude data is passed through a median filter to perform median processing. FIG. 3 is a block diagram showing an example of the air system and circuit configuration of the electronic blood pressure monitor of the embodiment. FIG. 4 is a flow chart showing the processing operation of the electronic blood pressure monitor of the embodiment. FIG. 3 is an explanatory diagram showing a smoothed envelope obtained by median filter processing. 1: Cuff, 5: Pressure sensor, 8: Bandpass filter, 9: CPU0 Patent applicant Tateishi Electric Co., Ltd. (Baka1
given name)

Claims (1)

[Claims] (1) A cuff, a pressurizing means for pressurizing the cuff, a depressurizing means for reducing the pressure inside the cuff, a pressure detecting means for detecting the fluid pressure inside the cuff, and a signal included in the output signal of the pressure detecting means. A pulse wave component detection means for detecting a pulse wave component; a pulse wave amplitude value calculation means for calculating a pulse wave amplitude value from the pulse wave component detected by the pulse wave component detection means; and a blood pressure value determining means for determining a systolic blood pressure value and a diastolic blood pressure value based on an output signal and an output signal of the pressure detecting means, wherein an odd number of pulses obtained by the pulse wave amplitude value calculating means is provided. An electronic device characterized by comprising means for smoothing a pulse wave envelope by performing median filter processing on wave amplitude data and using a value that is neither the maximum value nor the minimum value among the odd number of pulse wave amplitude data as the median value. Sphygmomanometer.