JPH01236035A - Electronic hemadynamometer - Google Patents

Abstract

PURPOSE:To correctly measure a maximum blood pressure value by extracting the sharpest positive peak in the positive peaks of pulse waves to be detected, and deciding the fluid pressure in the cuff corresponding to it to be the maximum blood pressure value. CONSTITUTION:When a maximum value PwM(n-1) of a pulse wave Pw3(i) is detected, a threshold Thbeta is executed from the PwM(n-1), and a point tU(n-1) to be crossed in the rising part of a Pw(i) and a point tD(n-1) to be crossed in the falling part are detected. A time T(n-1) from the tU(n-1) to the tD(n-1) is calculated, and it is stored. The time T(n-1) is a constant to evaluate the sharpness of the positive peak, and it indicates that the peak is sharper as the value is smaller. From Tm(1)-Tm(n-1) calculated so far, a minimum value is detected, and it is made into a TmMIN. A cuff pressure Pc(i) hourly corresponding to the TmMIN is made into a maximum blood pressure value PSYS. The maximum blood pressure value PSYS is displayed on a display 8 along with a minimum blood pressure value PDIA, a rapid exhaust value 5 is opened, and a subject above-elbow part is released from a pressurization. In such a way, the maximum blood pressure value can be correctly measured.

Description

[Detailed Description of the Invention] (a) Industrial Application Field This invention relates to an electronic blood pressure monitor that applies the vibration method. Specifically, the positive peak of the pulse wave that occurs during cardiac systole is the sharpest. The present invention relates to an electronic sphygmomanometer that uses the cuff pressure at a point in time as the systolic blood pressure value.

(B) Prior Art Conventionally, in an electronic blood pressure monitor to which the vibration method is applied, the systolic blood pressure value and the diastolic blood pressure value are measured in the following manner. First, a cuff is attached to, for example, the subject's upper arm, and the air within the cuff is pressurized using a pump or the like to compress the upper arm and temporarily ischemize the artery.

Next, when the air inside the cuff is gradually exhausted at a constant speed, the air pressure inside the cuff (hereinafter referred to as cuff pressure) increases as shown in Figure 5 (a).
), a fluctuation component appears. This fluctuating component is called a pressure pulse wave, in which changes in intravascular volume are transmitted through the soft tissue of the upper arm to the cuff, and appear as pressure changes.

This pressure pulse wave is separated by filtering processing (
5(b)], the amplitude value AP is calculated (see FIG. 5(C)). From this amplitude value A4 column, the maximum amplitude value Aax is extracted, and this maximum pulse wave amplitude value 8 is extracted. 〇.Before the appearance,
Amplitude value Apo, 70% of A P m a x
is extracted. When this AI-o, 7 appears, t. , 7 is taken as the systolic blood pressure value SYS.

On the other hand, the change point A1 when the pulse wave amplitude value A changes from a rapid decrease to a slow decrease after the appearance of the maximum pulse wave heart rate value A Pmax. is extracted. The cuff pressure PC corresponding to this A pl+ appearance time tD is taken as the diastolic blood pressure value DIA.

(c) Problems to be Solved by the Invention Since the conventional blood pressure determination method described above is purely statistical, there is a problem in that the measurement error of the systolic blood pressure value becomes large in the case of elderly people and hypertensive patients. .

This invention has been made in view of the above, and aims to provide an electronic blood pressure monitor that can accurately measure systolic blood pressure values.

(d) Means for Solving the Problems In order to solve the above problems, the electronic blood pressure monitor of the present invention has the configurations 1 to 11 listed below.

i: a cuff; 11: pressurizing means for pressurizing the fluid within the cuff; 111
: A pressure reducing means that rapidly or slowly decompresses the fluid in the cuff; iv. A pressure detecting means that detects the fluid pressure in the cuff; (2) A pulse wave detecting means that detects a pulse wave at the site where the cuff is attached. and (iii) a blood pressure value determining means for determining a blood pressure value based on the fluid pressure detected by the pressure detecting means and the pulse wave detected by the pulse wave detecting means. comprising a peak extracting means for extracting the sharpest positive peak among the positive peaks of the pulse wave detected by the pulse wave detecting means; The fluid pressure within the cuff that corresponds to the sharpest positive peak detected is determined as the systolic blood pressure value.

(E) Function The function of the electronic blood pressure monitor of the present invention will be explained below with reference to FIG.

The pressure Po of the cuff is transmitted through the soft tissue at the cuff attachment site and reaches the outer wall of the blood vessel. This pressure acts in the direction of applanating the blood vessel, whereas the intravascular pressure P acts in the direction of expanding the blood vessel. The relationship between these two forces, ie, the cuff pressure PC and the intravascular pressure P, determines the volume of the blood vessel. The relationship between the transmural pressure P, (=P8-PC1 intravascular pressure difference) and the intravascular volume ■ is shown in FIG.

The intravascular pressure P, is constantly changing, and the fluctuation changes the intravascular volume ■. This internal volume change is transmitted through the soft tissue to the cuff. At this time, since the amount of change in the cuff volume is sufficiently small compared to the intracuff volume, it is considered that the intravascular volume is proportional to the cuff pressure change. In other words, it can be said that the pressure pulse wave generated within the cuff is approximately proportional to the intravascular volume ■.

In FIG. 4, the transmural pressure P5 is plotted on the horizontal axis, and the intravascular volume ■ is plotted on the vertical axis. Transmural pressure PL
is expressed by the following equation (1) using blood pressure fluctuation component ΔP, mean blood pressure M, and cuff pressure Pc.

Pt-8P+M-PC・(1) M, PC contributes to varying the operating point of the p,-v curve.

8P is converted into a volume pulse wave by the Pt-■ curve.

This volume change can be captured as a pressure pulse wave as described above.

Now, regarding the blood vessel characteristics, as can be understood from FIG. 4, when P is zero, the change in intravascular volume (2) due to a constant change in Pt becomes maximum. In other words, transmural pressure P,
When is zero, the blood vessels are the softest.

Therefore, as shown in the intravascular pressure waveform W2, at the systolic blood pressure point (in the waveform W2, the point on the right side of the paper in FIG.
, -0, the positive peak of the intravascular volume converted by the PL-V curve, that is, the corresponding pressure pulse waveform P
The positive peak of 2 is the sharpest.

On the other hand, when the intravascular pressure waveform W1 is present, the blood vessel is mostly applanated, the intravascular volume changes little with respect to intravascular pressure fluctuations, and the pulse waveform P is positive. The peak becomes duller. Conversely, at the time of intravascular pressure waveform W6, blood is flowing within the blood vessel with relatively little resistance, and as expected, there is little change in intravascular volume with respect to intravascular pressure fluctuations, and the positive peak of pulse waveform P6 is It becomes dull.

Therefore, the cuff pressure at which the positive peak of the pulse waveform becomes the sharpest can be taken as the systolic blood pressure value.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In this embodiment, the present invention is applied to a cuff-type electronic blood pressure monitor, and FIG. 3 is a block diagram illustrating the configuration of the electronic blood pressure monitor according to the embodiment.

2 is a well-known cuff, and this cuff 2 includes a pressure sensor (pressure detection means) 3, a pressure pump (pressurization means) 4, a rapid exhaust valve (pressure reduction means) 5, and a slow exhaust valve (pressure reduction means). 6 is connected. The output signal of the pressure sensor 3 is sent to the CPU 7
is loaded into. In addition, a pressurizing pump 4, a rapid exhaust valve 5,
The slow exhaust valve 6 is controlled by the CPU 7.

The CPU 7 has a function of detecting a pulse wave from the output signal of the pressure sensor 3, a function of detecting the sharpest positive peak from the detected pulse wave, and the like.

A display 8 such as a liquid crystal display and a start switch 9 are connected to the CPU 7.

Next, the operation of this embodiment of the electronic blood pressure monitor will be explained.

First, the cuff 2 is attached to the upper arm of the subject.

Then, the start switch 9 is turned on, the pressurizing pump 4 starts operating, and pressurizing starts [Step (hereinafter referred to as ST).
)1, see Figure 3]. At Sr1, it is determined whether the cuff pressure PC has become equal to the pressurization target value Ps. If this determination is No, wait at this Sr1 and Y
If the result is ES, the process branches to Sr1.

At Sr1, the CPU 7 stops the pressurizing pump 3 and opens the slow exhaust valve 6 to start slow exhaust.

In Sr1, cuff pressure Pc(il) is sampled.

The period of this sampling is usually 10 to 50 m5ec, and 1 is the number of the sampling point.

In Sr1, the sampled P c(i) is subjected to digital sampling processing to detect the pulse wave Pwl(0,). Furthermore, in Sr1, the pulse wave P w + ti,
is differentiated to calculate the differential pulse wave Pwz+t+ (see FIG. 1).

In Sr1, it is determined whether a point Cp (.) where the differential pulse wave Pw2 (il exceeds a predetermined threshold Thα) has been detected. Cp(n) is a point that divides the pulse wave, and if this determination is NO , return to Sr1 and set the cuff pressure P c (
Continue sampling i). Sr1 judgment is YES
In this case, the process proceeds to determination of Sr1. In Sr1, Cp(
Determine whether nl is equal to C01, and this determination is Y
In the case of ES, the process returns to Sr1. This judgment is C
If there are two or more data of p (.), the processing from ST9 onward cannot be performed, so C0° is provided to determine that there are two or more data.

If the determination of Sr1 is NO, branch to Sr1 and C00
The minimum value of cuff pressure P((il) near the time of n
) Calculate the straight line Rii-1, passing between the two points. Then, from the cuff pressure waveform Pc(n-+) between Pcc(n-11 and Pec(nl), a straight line Ri-1 is subtracted to calculate the pulse wave Pw3.4. (STII).

In this way, the pulse wave P W 3 +1. , P C(n-
What is obtained by subtracting −, , according to 11 is the pulse wave P w lLi detected by digital filtering.
This is because the + value inevitably distorts the waveform and is not suitable for detecting the sharpest negative peak.

In addition, pulse wave pw3. ．． To find the cuff pressure P.

91, and the cuff pressure PeL,+ may be omitted from the straight line connecting these peak points, and the design can be changed as appropriate.

In 5T12, the maximum value Pw□7 of the pulse wave Pw, , +, + in the section sandwiched by FCC(11-11 and Pec(nl)
-1. is detected. Furthermore, in 5T13, this Pw□
From h-11, a threshold Thβ is applied, and P w
The point jll(n-1+ and the point si,].-1, which intersects at the rising part of ti) is detected.This Thβ
is usually set to 0.1 to 0.5 mmHg, but it is not an absolute value, but may be a relative value of what percentage of the wave height of each peak of the pulse wave Pw3+=+.

In the next 5T14, the time T from tp(n-n to jD(n-11, .-1) is calculated and stored. This time T(n-11 is the sharpness of the positive peak. This is a variable to be evaluated, and the smaller the value, the more sharp it is.

In 5T15, T (n-1
1 is smoothed and set as Tm(r+-l).

T1□,,=(T121+T(□-+,+T+-1
)/3...(2) This is done to reduce the influence of artifacts such as respiratory arrhythmia and body movement, since T(.-1) is affected by these artifacts.

In 5T16 and 5T17, T1, +1 <Tm(n-
21, T m+r+-11<Tm(,,-31 or not is determined respectively, and only when both of these determinations are YES, proceed to 5T18, and if either is NO, S
Return to r1.

In 5T18, T63. From ~T0°-1, the minimum value is detected and set as T, . . . MIN.

In the next 5T19, the cuff pressure Pchi) which temporally corresponds to TmMll is set as the systolic blood pressure (IPsys).Then, this systolic blood pressure value P37.
At the same time, display it on the display 8 (Sr20), open the rapid exhaust valve 5, and release the subject's upper arm from the pressurization (Sr20).
21). Note that this invention does not involve determining the diastolic blood pressure value, so a description thereof will be omitted.

In the above embodiments, a cuff-type electronic sphygmomanometer is described, but the present invention is also applicable to a finger electronic sphygmomanometer that uses photoplethysmography.

(G) As described in detail of the invention, the electronic blood pressure monitor of the present invention includes peak extraction means for extracting the sharpest positive peak among the positive peaks of the pulse wave detected by the pulse wave detection means. The blood pressure value determining means determines the systolic blood pressure value from the cuff pressure corresponding to the sharpest positive peak extracted by the peak extracting means, and has the advantage that the systolic blood pressure value can be accurately measured. have.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram illustrating pulse wave data processing in an electronic blood pressure needle according to an embodiment of the present invention, FIG. 2 is a block diagram illustrating the configuration of the electronic blood pressure monitor, and FIG. FIG. 4 is a flowchart explaining the operation of the electronic blood pressure monitor, and FIG. 5(a), FIG. FIG. 5(C) is a diagram illustrating the principle of determining blood pressure values of a conventional electronic blood pressure monitor. 2: Cuff, 3: Pressure sensor, 4 Pressure pump, 5: Quick exhaust valve, 6: Slow exhaust valve, 7: CP
U. Patent Applicant: Tateishi Electric Co., Ltd. Agent, Patent Attorney: Shigeru Nakamura Written amendment to the procedure (spontaneous) February 22, 1989 1, Indication of the case 1989 Patent Application No. 64334 2, Name of the invention Electronic Blood Pressure Old 3 , Relationship with the case of the person making the amendment Patent applicant address 10 Hanazono Tsuchido-cho, Ukyo-ku, Kyoto City Name (2)
94) Tateishi Electric Co., Ltd. Representative: Yoshio Tateishi 4, Agent: ◎604 Address: 5F Kyoto Muro Building, 3-3 Mibu Kayo Gosho-cho, Nakagyo-ku, Kyoto City Voluntary amendment 7, "Scope of claims" in the statement of contents of the amendment Correct as shown in the attached sheet. 8. List of attached documents (1) A document stating the scope of claims, at least one copy of Japanese Patent Application No. 63-64334> 2. Scope of claims (1) Cuff and pressurization for pressurizing the fluid within the cuff a pressure means, a pressure reducing means for rapidly or slowly reducing the pressure of the fluid within the cuff, a pressure detecting means for detecting the fluid pressure within the cuff, and a pulse wave detecting means for detecting a pulse wave at a site where the cuff is attached. , an electronic sphygmomanometer comprising: blood pressure value determining means for determining a blood pressure value based on the fluid pressure detected by the pressure detecting means and the pulse wave detected by the pulse wave detecting means; Among the positive peaks of the pulse wave detected by the means,
The blood pressure value determining means includes a peak extracting means for extracting the sharpest positive peak, and the blood pressure value determining means determines the fluid pressure in the cuff corresponding to the sharpest positive peak extracted by the peak extracting means as the systolic blood pressure. An electronic blood pressure monitor characterized by determining the value. With Hell as a quasi, each level is lower by a predetermined level.
Shigenobu Nakamura

Claims (1)

[Claims] (1) a cuff, a pressurizing means for pressurizing the fluid within the cuff, a pressure reducing means for rapidly or slowly reducing the pressure of the fluid within the cuff, a pressure detecting means for detecting the fluid pressure within the cuff; a pulse wave detection means for detecting a pulse wave at a site where the cuff is attached; and a blood pressure value determination means for determining a blood pressure value based on the fluid pressure detected by the pressure detection means and the pulse wave detected by the pulse wave detection means. In an electronic blood pressure monitor comprising: a positive peak of the pulse wave detected by the pulse wave detection means;
The blood pressure value determining means includes a peak extracting means for extracting the sharpest positive peak, and the blood pressure value determining means converts the fluid pressure of the cuff pressure corresponding to the sharpest positive peak extracted by the peak extracting means into the systolic blood pressure. An electronic blood pressure monitor characterized by determining the value.