JPS61209636A - Electronic hemomanometer apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an electronic blood pressure measuring device, and particularly to an electronic blood pressure measuring device that measures blood pressure by detecting pulse wave amplitude.

(b) Conventional technology Conventionally known blood pressure measurement techniques include one based on the Rybarosoch-Korotkoff method, which is non-invasive. In an electronic blood pressure measuring device that uses the Rybarosoch-Korotkoff method, a cuff is wrapped around the arm and the cuff is pressurized to block blood flow, and then the pressure is gradually reduced until the blood begins to flow and the vascular table (Korotkoff) is used. Korotkoff sound is generated, and as the pressure is further reduced, the Korotkoff sound disappears. Blood pressure is measured by determining the cuff pressure at which the Korotkoff sound begins to occur as the systolic blood pressure, and by determining the cuff pressure at which the Korotkoff sound disappears as the diastolic blood pressure.

Other conventional blood pressure measurement techniques involve inserting a cannula into an artery to measure residual blood.

(c) Problems to be solved by the invention Among the conventional blood pressure measurement techniques described above, in the electronic blood pressure measurement device that adopts the Rybarosoch-Korotkoff method, the Korotkoff sound obtained is a minute signal, and the frequency band is 30 tl.
It is around z~15011z. This frequency band is easily generated by external noise or vibration noise, and there is a problem in that these noises often cause false detections, resulting in blood pressure measurement errors.

In addition, when measuring blood pressure using the direct method, arterial pressure is transmitted to an external blood pressure transducer using a cannula filled with physiological saline, but problems such as the length of the cannula, the inclusion of air bubbles, and zero point drift of the blood pressure transducer may occur. , resulting in an error in blood pressure. These errors can be reduced by handling, which requires skill and care, and requires considerable skill in measurement. Furthermore, the direct method has serious drawbacks in that it causes pain, discomfort, and mental tension to the subject, and there is a risk of vascular pain and bacterial infection.

In view of the above, an object of the present invention is to provide an electronic blood pressure measuring device that does not cause pain or discomfort to the person to be measured and is less susceptible to external noise, vibration noise, etc.

(d) Means and operation for solving the problems The electronic blood pressure measuring device of the present invention includes a cuff, a pressure system connected to the cuff for pressurizing or depressurizing the cuff, and a pressure system for detecting the cuff pressure. a sensor, a pulse wave sensor that detects pulse wave components in the process of changing cuff pressure, a pulse wave amplitude extraction means that extracts the amplitude of the pulse wave sequentially over time, and a pulse wave amplitude sensor that extracts the maximum value of the pulse wave amplitude. The maximum value extracting means moves the representative data through an area surrounded by an envelope of a predetermined number of data including the representative data of the pulse wave amplitude extracted time-sequentially and a straight line connecting both of the data. a first area maximum value extracting means for calculating the maximum value of the area calculated on the higher cuff pressure side than the cuff pressure corresponding to the pulse wave amplitude maximum value; second area maximum value extraction means for calculating the maximum value of the area calculated on the lower pressure side than the cuff pressure corresponding to the cuff pressure; and a cuff corresponding to the area maximum value extracted by the first area maximum value extraction means. blood pressure determination means for determining the systolic blood pressure also based on the pressure, and determining the diastolic blood pressure based on the cuff pressure corresponding to the maximum area extracted by the second area maximum value extraction means.

In this electronic blood pressure measurement device, the cuff pressure, pulse wave component, and pulse wave amplitude are each detected during the depressurization process after the cuff is pressurized by the pressure system. Then, for a predetermined number of pulse wave amplitude data, the area surrounded by the envelope of these data and a straight line connecting both data is calculated in time order. Then, the maximum area is extracted for each of the high pressure side and low pressure side of the cuff pressure corresponding to the maximum amplitude of the pulse wave, and the cuff pressure corresponding to the maximum area extracted for each of these high pressure side and low pressure side is determined,
Systolic blood pressure and diastolic blood pressure are determined based on these cuff pressures.

The pulse wave component used for blood pressure determination has a frequency band of IH.
Since it emits a very low frequency of z~19tlz, external noise and vibration noise are hardly mixed in.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a block diagram of an electronic blood pressure monitor in which the present invention is implemented. In the figure, the cuff is a rubber bag that is wrapped around the arm, and is connected to an exhaust valve 3 and a pressure pump 4 that constitute a pressure system 2 through a rubber tube 5. Further, the pressure sensor 6 is also connected to the cuff pressure through the rubber tube 5, and converts the cuff pressure into an electrical signal. The output of the pressure sensor 6 is connected to the input terminal of the amplifier 7, and the output electric signal of the pressure sensor 6,
That is, the cuff pressure signal is DC amplified by the amplifier 7. The output terminal of the amplifier 7 is connected to one input terminal of the A/D converter 8 and also to the input terminal of the bandpass filter 9. The output terminal of the A/D converter 8 is connected to CPU10,
The output of the amplifier 7 and the output of the bandpass filter 9 are respectively A/
The signal is converted into a digital signal by the D converter 8, and then taken into the CPU10.

The CPU 10 has a function of executing predetermined processing according to a built-in program and determining blood pressure values such as systolic blood pressure and diastolic blood pressure, and the determined blood pressure values are displayed on the display unit 11.

Furthermore, when a measurement start key (not shown) is operated, the CPU 10 starts operating the pressurizing pump 4 and pressurizes the cuff 1 in response to a command a, and controls the displacement of the exhaust valve 3 by the command. do. In addition, the cuff pressure from the amplifier 7,
The pulse wave component from the bandpass filter 9 is read at a predetermined sampling period according to commands c and d.

With this electronic blood pressure monitor, put the cuff pressure around your arm, operate the measurement start key to activate the pressure pump 4, pressurize the cuff 1 to a predetermined pressure, and then stop the operation of the pressure pump 4. When the exhaust valve is opened slowly, the cuff pressure gradually decreases, and the output signal of the pressure sensor 6 becomes as shown in FIG. Figure 3 (bl
It becomes as shown in .

CPU10 determines the average blood pressure, systolic blood pressure, and diastolic blood pressure from the detected cuff pressure and pulse wave amplitude (peak) value according to the flow described below. Next, the processing operation will be explained with reference to the flowchart shown in FIG.

First, when the measurement start key is pressed to start operation, the pressurizing pump 4 starts operating according to command a [step ST (hereinafter abbreviated as ST) 1], and the cuff pressure is increased until the cuff pressure is sufficient for measurement. Cuff pressure is increased (Sr2). When the cuff pressure reaches a predetermined cuff pressure, the operation of the pressurizing pump 4 is stopped and pressurization is stopped (Sr3), and at the same time, the exhaust valve 3 is evacuated at a very slow speed according to a command, and depressurization is started (Sr1). Then, according to command C, every T (example: 100m5ec),
The output of the amplifier 7, that is, the cuff pressure, is A/D converted and captured and stored (Sr1). Similarly, by command, T1
(Example: Every 10m5ec), the output of the bandpass filter 9,
That is, the pulse wave component is A/D converted by the A/D converter 8, captured, and stored (Sr1).

Next, a differential operation is performed for each point of the discrete data of the A/D converted pulse wave (Sr1). This differential calculation formula is Σ(f(r++j) −f(n−j)) X jM(n
)=□.

FIG. 11 shows the waveform obtained as described above after differential calculation and the pulse wave waveform before differentiation. The figure (a) is a differential waveform, and the same figure (bl is a pulse wave waveform).

Next, maximum value extraction processing of the differential pulse wave is performed. That is, S
Following the differential calculation of r1, it is determined whether the maximum value of the differential pulse wave has been detected (5T8), and the maximum value of the differential pulse wave is detected (Sr1) until it is detected. This process uses the current differential value,
Compare it with the highest value up to that point, and if the current value is larger, update it, and if that value is not updated within a certain period of time (for example, 3 seconds), that value is set as the maximum differential pulse value. .

Therefore, if the differential value is updated and the above-mentioned fixed time does not pass, the determination of whether the maximum jlyi of the differential pulse wave is detected by 5TIO is No, the process returns to Sr1, and the differential pulse wave maximum value detection processing is performed in real time. is repeated. When the maximum value of the differential pulse wave is detected, the determination of 5TIO becomes YES, and the maximum value of the differential pulse wave is stored (STII). And again, Sr.
The process returns to step 1, but this time the determination as to whether the maximum differential pulse wave value of Sr1 has been detected is YES, so the process moves to 5T12 and pulse wave division processing is performed.

In this pulse wave division process, the maximum differential pulse wave value α% (α: 10 to 20) extracted in Sr1 is set as the threshold level, the intersection point between this level and the differential pulse wave rise curve is found, and the process corresponding to the intersection point is determined. Points on the pulse waveform are defined as division points. 12th
TI shown in the figure (the line is the threshold level,
dl, d2, d3. ... is the dividing point.

The maximum value of the pulse wave is detected for each segment obtained by this pulse wave division (ST13). The maximum value of this pulse wave is defined as the pulse wave peak. Then, the maximum value among the pulse wave peaks obtained for each division is detected.

This pulse wave maximum value peak value detection compares the previous pulse wave peak value and the current pulse wave peak value, and if the current pulse wave peak value is large, updates and stores it to the larger pulse wave peak value, Thereafter, if the pulse wave peak value is not updated for a predetermined period of time or longer, the pulse wave peak value is stored as the pulse wave maximum peak value (ST17). The cuff pressure corresponding to this pulse wave maximum peak value is stored as the mean blood pressure CM.

When the pulse wave maximum peak value is stored, the determination as to whether the pulse wave maximum peak has been detected in 5T14 becomes YES, and then it is determined whether the pulse wave peak is less than or equal to β% (β: 40 to 60) of the maximum peak. (STlB). If it is not below β%, Sr5
Return to cuff pressure A/D conversion/memory (Sr5),
Pulse wave A/D conversion/storage (Sr1), pulse wave peak detection (Sr1)
Processes such as T14) are repeated.

When the pulse wave beat becomes less than β% of the maximum peak, 5TI8
The judgment becomes YES, and this state means that the pulse wave peak value necessary for measurement has already been measured, and then the CPU
A command is output from IO to the exhaust valve 3. As a result, the exhaust valve 3 shifts to rapid exhaust (ST19).

This completes real-time processing such as pulse wave differential calculation and pulse wave peak detection in the cuff pressure reduction process.

Thereafter, a predetermined process is executed on the pulse wave peak value obtained through this real-time process, and the process moves to blood pressure determination process for the systolic blood pressure and diastolic blood pressure. Next, the procedure of these blood pressure determination processes will be explained.

After rapid evacuation, for the data string of the extracted pulse wave peak (Pp(n)) at a higher cuff pressure than the pulse wave maximum peak (Pmax), the area surrounded by the envelope line and the straight line (a(n)l is calculated (ST20).

A specific example of calculating the area a(n) will be explained with reference to FIG.

In FIG. 13, n on the X-axis indicates the pulse wave number, and the y-axis indicates the corresponding pulse wave peak. Pulse wave number n
The area a (n) represented by is the point (n-2,0), (
n-2, Pp(n-2)), (n+2゜Pp(n-2)
), (n+2.O), from the area of the trapezoid, the point (n
-2,0), (n+2. Pp(n+2)), (n-
1, Pp(n-1)), (n, Pp(n)), (n+
l, Pp(n+1)), (n+2, Pp
(n+2)) and (n+2.0).

Points (n-2, 0), (n-2, Pp (n-2)), (
n+2. Pp(n-2)) and (n+2.0)
The area of the trapezoid made by is the point (i, O) and the point (++1.0)
If each interval of [i is from n-2 to fi+l] is h, then 1/2 ・4 h (Pp(n+2) 10Pp(n
-2)).

On the other hand, Takuchi, 0), (i, PP(+) ), (i+
1, Pp(n+1)) and (n+1.0) (i is from n-2 to n+1) The area Q(i) of the trapezoid is
Q(i) −1/2 h (Pp(i) +Pp(n+
1)). Therefore, the area a (n) is = h (4(Pp(n+2)+Pp(n-2)
)-(Pp(n-2)+Pp(n-1))+(Pp(
n-1)+Pp(n))+(Pp(n)+Pp(n
+1))+(Pp(n+1)) +Pp(n+2))
))■ -h (3(PI)(n+2)+Pp(n-2))-2
(Pp(n-1)+Pp(n) 10Pp(n+1))
) can be expressed as If h=1, a (n) is a (n
) = (Pp(n+2> + Pp(n-2)
-(Pp(n-1)+Pp(n) +Pp(n+1))
) can be calculated.

However, the points (n - 1, Pp (n - 1)), (n, Pp
(n)), (n + 1, Pp(n+1)), if at least one point (n+2. Pp(n+2)) and (n −
2, Pp(n-2)), this means that the envelope deviates from the range corresponding to the systolic blood pressure,
Assuming that the blood pressure is within the average blood pressure range, let a(n)=0.

This area a (n) is calculated for each pulse wave number by advancing the pulse wave number n of the pulse wave peak shown in FIG. 1 fb) by -1. Then, the area sequence (a
(n)) is obtained.

Next, the area sequence (from a(n)l, detect the maximum area ST2)), and the cuff pressure value corresponding to the pulse wave amplitude sequence group that gives this maximum area value is determined by CI [see Figure 1 (a+)]. ]
and the mean blood pressure value CM that has already been extracted and stored.
(From the reference color in Figure 1 (al), the systolic blood pressure value CS
is determined (Sr22).

C3=3/4 (CI-CM)+0M It has been experimentally confirmed that the systolic blood pressure calculated and determined by this formula is appropriate and practical.

Next, for the data string of the extracted pulse wave peak (Pp(n)) on the lower cuff pressure side than the pulse wave maximum peak (Pmax),
The sequence of areas (a(n)) surrounded by the envelope and the straight line is 5T
Calculate in the same manner as in case 20 (Sr23).

Next, from the area sequence (a(n)l (see the right side of Figure 1 (C)), the maximum area is detected 5T24), and the cuff pressure value CD corresponding to this maximum area value (Figure 1 (a) ) is determined as the diastolic blood pressure value (Sr25).The systolic blood pressure and diastolic blood pressure are then displayed on the display unit 11 (5T26), and the measurement is ended.

Next, specific processing of each subroutine from 5T20 to 5T25 in the main flow will be explained.

Calculation of high cuff pressure side area sequence (Sr20)> When entering 5T20 in the main flow, as shown in FIG.
(Sr12) and determine whether Nmax-n (
Sr53). Here, Nmax is Pmax - Pp(N
max ) (the cuff pressure corresponding to this N max is the mean blood pressure CM), and while 5T53 is No, area calculation is performed on the high cuff pressure side. That is, if the determination of 5T53 is NO, it is determined whether the following formulas hold true (Sr54.5T55.5
T56).

If even one of these equations holds, then pp(n)
, Pp(n-1), and Pp(n+1) exist above the straight line, so the area a(n) is set to O (Sr57). When none of the formulas hold true, a (n) = -(P p(n+2)+ P p
(n-2))-(Pp(n-1) -1-Pp(n)
+Pp(n+1)) ・・・・・・(Calculate 41 and calculate (
Sr18), return to Sr12, add +1 to n, and repeat the area calculation. When Ntnax-n is reached at 5T53, the calculation of the area a (n) on the high cuff pressure side is completed and the process returns.

Detection of the maximum area on the high cuff pressure side (Sr21)> When entering 5T21 in the main flow, as shown in FIG. ), then add +1 to n (Sr63) to determine whether N, may = n or not.
T64), until this judgment becomes YES, compare the area value a (n) without sequentially reading out the maximum area value Ama up to that point 5T65), If the read area value a (n) is small, continue reading 5T63) Returning to , if the area value a (n) is large, the area value a (n) is updated as the new maximum area value Amax (Sr66). Also, assuming that n at that time corresponds to the maximum area value An+ax,
Stored as Nantax (Sr17), Sr13
, and from then on, increase n by +1 to get the maximum area value A
The update process for x continues. When Nmax=n at 5T64, detection of the maximum area on the high cuff pressure side is completed and the process returns.

Determination of systolic blood pressure (Sr22)> When entering 5T22 in the main flow, as shown in FIG. 7, first, the cuff pressure CM at the time when the maximum value P max of the pulse wave peak is obtained is substituted into PRESSI (Sr71). .

Next, the pulse wave peak p p (N a
The cuff pressure CI at the time when max) is obtained is substituted into PRESS2 (Sr72). and (2(PRESS2)+
Calculate (PRESSI)l +3 to determine the systolic blood pressure CS (5T73) and return.

<Calculation of low cuff pressure side area (Sr23)> When entering 5T23 in the main flow, first the N
max-2 is set to n (5T81), n is further increased by 1 (Sr12), and it is determined whether n is equal to Nend -2 (Sr83). Here, N end is the number of the last extracted pulse wave. While the determination in 5T82 is No, it is determined in 5T84 to 5T86 whether or not the above-mentioned formulas 1, 2, and 3 hold true, as in the case of the high cuff pressure side product sequence calculation shown in FIG. , if even one holds true, a(n)=
O and 5T87), if neither formula holds true,
Calculate the area a (n) using formula 4.5T88), 5T
Return to 82.

After that, add +1 to n in 5T82, and n = Nend
Repeat the area calculation until . n=Nend in 5T83
When it becomes 2, the calculation of the area a (n) on the low cuff pressure side is completed and the process returns.

<Detection of maximum area on low cuff pressure side (Sr24)> When entering 5T24 in the main flow, as shown in FIG. 9, first, the maximum area value Amax is set to 0 (Sr91), and then n is set to Nmax -2. 5T92), then add 1 to n (Sr93), and judge whether n is equal to Nend 2 (Sr94). Then, increase the area value a' (n) and the maximum area value A max until this judgment becomes YES. Compare and update the maximum area value A max (Sr95.
5T96), the updated n is stored as N a max (Sr97), and the process returns to 5T93, whereupon the process of updating the maximum area value Amax is continued. When n=Nend-2 in 5T94, detection of the maximum area on the low cuff pressure side ends and returns.

Determination of diastolic blood pressure (Sr25)> When entering 5T25 in the main flow, as shown in Fig. 10, the pulse wave peak Pp (N a
The cuff pressure CD at the time when max ) is obtained is the diastolic blood pressure (
STIOI). After making a decision, return.

In the manner described above, each blood pressure can be measured from the cuff pressure and pulse wave. It has been confirmed that the maximum, minimum, and average blood pressure values determined based on the above-mentioned algorithm match the blood pressure measurement values obtained from the Korotkoff sounds.

Further, in the above embodiment, a bandpass filter is used to extract the pulse wave, but in this invention, a digital filter may be used instead, and the cuff pressure signal including the pulse wave component is The cuff pressure signal and the pulse wave component may be separated by software processing different from a digital filter.

In addition, in the above embodiment, the pulse wave is divided by calculating the pulse wave differential value in order to extract the pulse wave peak value, but in this invention, the extraction of the pulse wave peak value is not limited to this. do not have.

(F) Effects of the Invention According to the electronic blood pressure measuring device of the present invention, unlike conventional electronic blood pressure measuring devices, blood pressure is measured using cuff pressure and amplitude information of pulse waves, which are vibrations within the cuff head. Therefore, the frequency band of this pulse wave is 1) 1z to 1011z,
Since the frequency is very low, by providing a filter for that band, it is possible to remove most of the external noise and vibration noise and prevent them from entering, so the amplitude information of the pulse wave can be processed without any distortion. It is possible to perform calculations using different means, and it is possible to accurately measure blood pressure even in an environment where there is a lot of noise. In particular, blood pressure determination involves calculating the area surrounded by the envelope of the pulse wave amplitude that does not include noise components and a straight line connecting both end data of a predetermined number of data, and determining blood pressure using this partial area as a parameter. Since the difference in size of the area is noticeable, highly accurate blood pressure measurement can be performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the outline of the electronic blood pressure measuring device of the present invention, and FIG. 1 (al is a diagram showing the cuff pressure reduction process, and FIG. FIG. 1 (C) is a diagram showing a series of pulse wave peaks; FIG. 1 (C) is a diagram showing a time series distribution of the partial area surrounded by the envelope and straight line portion of pulse wave peaks; FIG. The block diagram of the electronic blood pressure monitor, Figures 3(a) and (b), are diagrams showing changes in cuff pressure and changes in pulse wave amplitude obtained during the cuff pressure reduction process in the electronic blood pressure monitor, and Figure 4 is a block diagram of the electronic blood pressure monitor. , a main flow diagram for explaining the operation of the electronic blood pressure monitor, and Figures 5 to 10 are flow diagrams specifically showing a part of the routine of the main flow. For pressure side area column calculation,
Figure 6 shows maximum area value detection on the high cuff pressure side, Figure 7 shows systolic blood pressure determination, Figure 8 shows area sequence calculation on the low cuff pressure side, and Figure 9 shows the area sequence calculation on the low cuff pressure side.
The figure is a flowchart showing the subroutine for detecting the maximum area value on the low cuff pressure side, and Figure 10 is a flowchart showing the subroutine for determining the diastolic blood pressure.
Figure 1 ta + fbl is a waveform diagram showing the differential pulse wave waveform and pulse wave waveform of the electronic blood pressure monitor, and Figure 12 (al (bl is the differential pulse wave waveform for explaining pulse wave division in the electronic blood pressure monitor). FIG. 13 is a diagram for explaining partial area calculation on the high cuff pressure side of the electronic blood pressure monitor. 1-Cuff, 2: Pressure system, 6: Pressure sensor, 7 : Amplifier, 8: A/D converter, 9: Bandpass filter, 10: cP
U, 11: Display section. Patent applicant Tateishi Electric Co., Ltd. Agent
Patent Attorney Shigeru Nakamura/-rio-7 O0

Claims (1)

[Claims] (1) A cuff, a pressure system connected to the cuff to pressurize or depressurize the cuff, a pressure sensor that detects cuff pressure, and a pulse wave sensor that detects pulse wave line segments in the process of changing cuff pressure. , pulse wave amplitude extraction means for extracting the amplitude of the pulse wave in time sequence; pulse wave amplitude maximum value extraction means for extracting the maximum value of the pulse wave amplitude; and representative data of the pulse wave amplitude extracted in the time sequence. an area calculation means for sequentially calculating an area surrounded by an envelope of a predetermined number of data including the data and a straight line connecting both end data of the number of data while moving the representative data; and a cuff corresponding to the maximum pulse wave amplitude value. a first area maximum value extracting means for calculating the maximum value of the area calculated at a higher cuff pressure than the pressure; determining the systolic blood pressure based on the cuff pressure corresponding to the area maximum value extracted by the second area maximum value extraction means and the first area maximum value extraction means; An electronic blood pressure measurement device comprising blood pressure determining means for determining the diastolic blood pressure based on the cuff pressure corresponding to the maximum area extracted.