JPH02309927A - Electronic hemadynamometer - Google Patents

Abstract

PURPOSE:To decide the deficiency of pressurization and the degree thereof by subjecting the membership functions for the respective parameters selected by a membership function selecting means to prescribed logical operations to estimate a relative pressure and detecting the deficiency of pressurization therefrom. CONSTITUTION:The parameters, such as pulse wave pressure AMP, pulse wave integration level RAW, waveform width ratio WID, and flexion index CON, are calculated and used in order to evaluate the waveform of the pulse waves. For example, the cut port corresponds to the membership function of the relative cuff pressure Pc' to the pulse wave pressure AMP* when the pulse wave pressure AMP is actually measured and is cut by thin pulse wave pressure AMP*. Such membership function is obtainable similarly with the other parameters as well. The relative cuff pressure to the max. value of the functions obtd. by subjecting the membership functions for the respective parameters obtd. in such a manner to the prescribed logical operations at the time of multiplication and addition is determined. The degree at which the present cuff pressure deviates from the systolic pressure is known in this way and the decision of the presence or absence of the deficiency of the pressurization and the degree thereof is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an electronic blood pressure monitor capable of detecting insufficient pressurization.

(b) Conventional technology A blood pressure measurement method called the Ribarocchi method involves, for example, attaching a cuff to the upper arm, pressurizing the air in the cuff to a set value (pressurizing the cuff), and then After ischemizing the artery, the air inside the cuff is evacuated at a constant slow velocity, and the systolic and diastolic pressures are determined based on the cardiovascular information generated during this process, which is safer and easier to measure than the direct method. It features a simple procedure and is used in many automated electronic blood pressure monitors used in medical settings and at home.

Electronic sphygmomanometers employing the Rivalotchi method are known to include an oscillometric type that uses pulse waves as cardiovascular information and a Korotkoff type that uses Korotkoff sounds as cardiovascular information. In an oscillometric electronic blood pressure monitor, a pulse wave is detected during the process of slowly pumping the cuff, and, for example, changes in the amplitude of this pulse wave are captured to determine the systolic pressure.
It determines the diastolic pressure (hereinafter both are collectively referred to as blood pressure value). On the other hand, the Korotkoff electronic blood pressure monitor
During the slow evacuation process, a microphone is used to detect the Korotkoff sounds produced by the blood vessels and determine the blood pressure value.

(C) Problems to be Solved by the Invention In both types of electronic blood pressure monitors, it is necessary to increase the air pressure inside the cuff (cuff pressure) to the systolic pressure or higher before taking a measurement. If the set value is lower than the systolic pressure, the blood pressure value cannot be determined in principle.

With the oscillometric electronic blood pressure monitor described above, insufficient pressurization is not detected until the end of the measurement. Therefore, even if the pressure is insufficient, the measurement continues, and it may become clear that the pressure is insufficient only after some time has passed, and the measurement may have to be taken again.

On the other hand, with a Korotkoff-type electronic blood pressure monitor, insufficient pressurization can be determined from the presence or absence of Korotkoff sounds at the start of measurement. However, it is not possible to determine to what extent the pressure is insufficient, and even if pressurization is performed again, the pressure may still be insufficient.

Additionally, since a highly sensitive microphone is used, ambient noise may be mistaken for Korotkoff sound and unnecessary re-pressurization may be performed.

As described above, with conventional electronic blood pressure monitors that use the Noribarocchi method, subjects must carefully set the set value to avoid insufficient pressurization, which is cumbersome. There was a risk of causing pain or depression to the subject due to false detection of insufficient pressurization. Furthermore, there was also the problem that measurement efficiency decreased due to re-measurement.

The present invention has been made in view of the above, and an object of the present invention is to provide an electronic blood pressure monitor that can determine not only insufficient pressurization but also the extent to which the pressurization is insufficient.

(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 listed in the following items 1-xi.

i: a cuff worn by the subject; ii; a pressurizing means for pressurizing the air within the cuff; iii
: Exhaust means for rapidly or slowly exhausting the air in the cuff; i■: Pressure detection means for detecting the air pressure in the cuff; ■: Cardiovascular information detection means for detecting cardiovascular information of the subject. , ■1: A blood pressure value determining means for determining a blood pressure value based on the air pressure detected by the pressure detecting means and the cardiovascular information detected by the cardiovascular information detecting means, : A pulse wave detection means for detecting a pulse wave from the subject; viii : From the pulse wave detected by the pulse wave detection means,
A pulse wave parameter calculating means for calculating a plurality of parameters representing the pulse wave waveform; membership function storage means storing X: membership functions corresponding to each parameter calculated by the pulse wave parameter calculation means, respectively, from the membership functions stored in the membership function storage means. Membership function selection means to select; The present invention is characterized by comprising a pressurization shortage detection means for detecting pressurization shortage based on the pressure.

(E) Function The function of the electronic blood pressure monitor of this invention is shown in Figures 1, 2 and 7.
This will be explained with reference to the figures. It is known that the pulse wave waveform changes with cuff pressure, and it can be expected to estimate how far the current cuff pressure is from the systolic pressure, that is, the relative pressure, from the pulse wave waveform.

To evaluate the pulse wave waveform, for example, as shown in FIG. 2, the pulse wave amplitude AMP, pulse wave integral level RAV, and waveform width ratio WI are used.
Parameters such as D and curvature CON may be calculated and used. Now, considering the pulse wave amplitude AMP, Fig. 7(a) shows the pulse wave amplitude AMP obtained for a large number of subjects.
This is a dot plot of the relationship between the pulse wave amplitude ΔMP and the relative cuff pressure PC''.What is shown in FIG. , and it is possible to employ this as a membership function.

If the pulse wave amplitude AMP is actually measured, this pulse wave amplitude AMP"
When Figure 7(a) is cut at
a), which corresponds to the membership function of the relative cuff pressure p% with respect to the pulse wave amplitude AMP".Such membership functions can be obtained similarly for other parameters (in Fig. 1, (b) (c) (d) (
(a). The function obtained by performing predetermined logical calculations such as multiplication and addition on the membership function for each parameter obtained in this way is, for example, as shown in (e) in Figure 1. The relative cuff pressure corresponding to the maximum value of the function can be estimated to be the most likely one.Once the relative cuff pressure can be estimated, it is possible to know how far the current cuff pressure is from the systolic pressure. , it becomes possible to determine the presence or absence of insufficient pressurization and its degree.

(f) Example An embodiment of the present invention will be described below based on the drawings.

FIG. 3 is a block diagram illustrating the configuration of the electronic blood pressure monitor of this embodiment. A cuff 2 is attached to the upper arm of the subject, and an exhaust valve 3, a pressurizing pump (pressurizing means) 4, and a pressure sensor (pressure detecting means) 5 are connected to the cuff 2. The exhaust valve 3 and the pressure pump 4 are controlled by MPU10. After the output signal of the pressure sensor 4 (hereinafter referred to as a cuff pressure signal) is amplified by an amplifier 6, one signal is directly inputted to an analog/digital (A/D) converter 8, where it is digitally converted and taken into the MPU10. On the other hand, the cuff pressure signal is input to a bandpass filter 7, and a pulse wave signal is detected. This pulse wave signal is also digitally converted by the A/D converter 8 and taken into the MPU10.

MPU10 has a function to calculate pulse wave waveform parameters,
A function to select a membership function based on the calculated parameters, a function to perform logical operations on the selected membership function to determine insufficient pressurization, and a function to determine the blood pressure value from the change in pulse wave amplitude mJ+ during the slow exhaust process. Equipped with functions, etc.

A data table and an operation program for the membership function are stored in the memory loa in MPU10. Furthermore, a display 9 is connected to the MPU10, and the determined blood pressure value and the like are displayed.

Next, the overall operation of the electronic sphygmomanometer according to the embodiment will be described below with reference to FIG.

First, the cuff 2 is wrapped around the upper arm of the subject, and blood pressure measurement is started. First, the MPU10 closes the exhaust valve 3, turns on the pressurizing pump 4, and starts pressurizing [Step (hereinafter referred to as ST) 1].

The MPU10 takes in the cuff pressure signal from the A/D converter 8 (Sr1), and determines whether the current cuff pressure has reached the set pressure Pco (Sr1). If this determination is NO, the process branches to Sr1, and if this determination is YES, the process branches to Sr4. That is, the processes Sr1 and Sr1 are repeated until the current cuff pressure reaches the set pressure p co. The set pressure P co may be fixed, or a setting switch may be provided to allow the subject to select it, and the design can be changed as appropriate.

At Sr1, MPU10 stops the pressure pump 4.

Then, the MPU10 takes in the pulse wave Pin(t), and sets the pulse wave Pw(t) to a threshold value T1. is applied to divide the pulse wave (see (b) in Figure 2)].Then, MPU10 divides the pulse wave from the pulse wave Pw(L) at the dividing point T * L % T II h
5T7), and this judgment is N.
If O, branch to Sr5; if YES, branch to Sr1
Branch to. In other words, Sr5~ until the pulse wave lasts for one night.
Repeat the process of ST7.

In Sr1, MPUl0 is calculated from the pulse wave Pw(t) by 4, which will be described later.
Calculate two parameters. Note that in this example, one pulse wave is detected and the parameters are calculated, but if several pulse waves are detected, parameters are calculated for each, and the average value is taken, higher l, zReliability can be obtained.

Furthermore, in Sr1, MPU10 estimates the repressurization set value p c+ from the parameters obtained in Sr1.

In 5TIO, this re-pressurization set value Pct is compared with the first set value PcO, and if the re-pressurization set value Pet is larger than the set value PCO (Pcl>Pc0), it is determined that there is insufficient pressurization.
Branch to TII, if Pcl is less than PCO (pct'
≦P,. ), it is determined that the pressurization is not insufficient and branches to 5T13.

At 5TII, the MPU10 causes the display 9 to display a message indicating insufficient pressurization. In addition to this display, or in place of this display, it may be configured to notify the subject of the insufficient pressurization by voice.

At 5T12, the MPU I O operates the pressurizing pump 4 again to perform repressurization to the repressurization set value P CI.

At 5T13, MPU10 determines the blood pressure value using an oscillometric method. In this blood pressure value determination process, the exhaust valve 3 is brought into a slow exhaust state, and the pulse wave amplitude during the slow exhaust process is captured. The pulse wave amplitude increases as the cuff pressure decreases, reaches a maximum when the cuff pressure is the average value of the systolic pressure and the diastolic pressure, and then decreases again. The cuff pressure when the pulse wave amplitude is about 50% of the maximum amplitude on the increasing side corresponds to the systolic pressure, and the cuff pressure when the pulse wave amplitude is about 70% of the maximum amplitude on the decreasing side corresponds to the diastolic pressure. Therefore, for example, the blood pressure value can be determined based on this. Note that the present invention does not include the blood pressure value determination process itself as a main part, so a detailed explanation will be omitted.

Further, the blood pressure value determination process may be performed by the Korotkoff method, and the design can be changed as appropriate.

At 5T14, MP[Jlo sets the exhaust valve 3 to a rapid exhaust state, and rapidly exhausts the cuff 2 to release the subject's upper arm from compression. Furthermore, MPU10 displays the determined blood pressure value on the display 9 (STI5).

Next, the pulse wave parameter calculation process (Sr1) will be described below with reference to FIGS. 2 and 5.

The electronic blood pressure monitor of this embodiment employs four types of pulse wave parameters: pulse wave amplitude AMP, integral level RAV, waveform width ratio WID, and curvature ratio CON. Of course, the pulse wave parameters are not limited to these four.

First, MPU10 searches for the time T I, , aXs Tl1il'l at which the pulse wave Pw(t) is maximum and minimum, and
Store the pulse wave maximum value PWmax and pulse wave minimum value PWmi, 1 corresponding to m a X and T min in memory 1, respectively.
0a (STIOI, see (a) in FIG. 2).

Then, P6.7 is subtracted from P Hmax to calculate the pulse wave amplitude AMP (ST102).

Next, the integral level RAV (%), which is the value obtained by normalizing the time average of the pulse wave Pw (L) by the amplitude AMP, is calculated using the following (1).
Calculate using the formula (ST103, see (b) in Figure 2)
.

Next, the waveform width ratio WID (%) is calculated (
ST104 to 5T108, see Figure 2 (C)), this W
ID is the time from the appearance of the maximum value Pw□8 of the pulse wave Pw(t) until it decreases to a predetermined threshold TH, normalized by the pulse wave period ('r, , -'r, L). This is the converted value.

First, the threshold value TH, is set using the following equation (2).
X in this formula (2) is a constant predetermined in the range of 0-1 (ST'104).

TH+=P-si. +AMPXx...(2)
Next, let time be Tmax (5T105), add sampling width Δt to this time (ST106), and determine whether the pulse wave Pw(t) for this L has become TH or less (ST107). ). ST I O7 judgment is N
If O, branch to 5T106; if YES, branch to 5T106.
Branches to T108. At 5T108, WID is calculated using the following equation (5).

Here, T d a c is the time when Pin(t)≦TH.

Finally, calculate the curvature ratio CON [%] (ST109~
5TIII). This CON is the maximum point of the pulse wave at a point Tc 11 Fl that internally divides the time interval (T, , , T, ,) between the maximum and minimum points within one beat by a certain predetermined ratio y. It is the relative ratio between the i line of sight connecting the minimum point and the pulse wave P curvature (1).

First, calculate T c a a using the following equation (4) (
ST109). Here, y is a constant preset in the range of 0 to 1.

Tcan= TmAx + (Tan Tmax) ×
V'...(4) Next, the level Ref of reference 1jα straightness in T can is calculated by the following equation (5) (STIIO).

Ref = P w --x A M P X y
``45) Then, CON is calculated using the following equation (6).

Next, the repressurization setting value estimation process is performed as shown in FIGS. 1, 6, and 7.
This will be explained with reference to the figures.

First, in 5T201 to 204, a classification (ranking) process is performed for each of the parameters AMPSRAV and WIDXCON obtained in ST8. Since the data table of the membership function, which will be described later, is discrete, a classification process is required to accommodate this, and specifically, this is performed using the following equations (7) to θω.

R1□=AMP/I, □...(7)
-R,,v= (RAI-0,,)/I,,v...
・(8) R,, ra = (W I D O,, = a
) / I, lid ... (9) Rco, l=
CON/I con・(10)
Here, l a, %p, Ir1v ,, l wid %
l can is each rank width. Also, Or
av s 0w1d is an offset value. RAV and W
Since both of the lowest ID values are not zero, for these, the offset values Orav and Owta are subtracted, respectively, and then division is performed by the rank widths r rmv and I wid.

After ST205, the parameters ranked in this way R11+1111% Rrmv −, Rwta
, Rcon is used to estimate the repressurization set point. Before explaining the specific processing, the data table will be explained.

Figures 7 (a), (b), (C), and (d) are dot plots of the measured data of AMP, RAV, WID, , CON obtained for a large number of subjects, with relative pressure Pc' on the horizontal axis. be. What is shown in each figure is a so-called probability distribution function in which variables are variable pressure and relative pressure, and these are employed as membership functions. In younger brother 7, the pulse wave parameters are AMP", RAV", WI
D", C0NI, AMP", RAV",
If we cut each membership function at W I D" and CON", the cuts are shown in Figure 1 (
It will be as shown in a)(b)(C)(d). Figure 7 (a
)(b)(C)(d) are AMP", RAV" respectively
, WI D"1.CON" can be viewed as a selected membership function.

In the electronic blood pressure monitor of this embodiment, the parameters and the relative cuff pressure Pc° are classified into ranks, and the membership functions are discretized and stored in the memory 10a in the form of a data table.

For example, the membership function for AMP is PC'
, AMP are divided into ranks m and n, respectively, and can be expressed by the following matrix.

If AMP is calculated and its ranked value is R
If st, p, then the column-column representation corresponding to R, □ is selected from the above matrix as the membership function corresponding to the value of this AMP.

Returning to the explanation of the process of Sr105 again, in 5T205, the initial value of the pointer j of the relative cuff pressure Pc' and the variable Pnmx that stores the maximum value of the multiplied membership function is set to 0. In Sr106, the above j is incremented by 1, and in 5T207, the membership function is multiplied by the following equation (11).

P = PiMp(J+ RaMp)XPrav(J+
Rrav)XP-=a(J, RWza)XPco, (
J, Rcor, )・” (If) In ST208, Sr1
It is determined whether P calculated in step 07 is greater than or equal to P MaM. If this determination is YES, the process branches to Sr110 and N
In the case of O, the process branches to 5T209. With Sr109, L P at this time is M IIIX % P 1ll.
Put it in aX. 5T210 determines whether j is less than or equal to m, and if this determination is No, branches to Sr106,
If YES, the process branches to Sr111.

For the processing of 5T206-210, the judgment of Sr110 is YES
This is repeated until the parameters AMP, RAV, WED are set as shown in FIG.

This corresponds to a process of calculating a function P by multiplying CON by a membership function and extracting its maximum value P0.

For Sr111, the obtained M m a x and p m a
From x, the relative cuff pressure Pc' is determined according to the following equation 02).

P c's −P cffitn + (Mmax
1) X Rpc ・”02) Here, Rpc is
This is the rank width of relative cuff pressure PC'.

In Sr112, the estimated relative cuff pressure PC' is reduced from the initial set value Pco, and the re-inflation set value Pc+ is set as i.
Determine lG. If the relative cuff pressure p % is positive, the set value P co is equal to or higher than the systolic pressure, and the re-inflation set value P
al becomes less than Pco, and the above-mentioned 5TIO judgment is NO.
becomes. Conversely, if the relative cuff pressure Pc° is negative, the set value PcO is less than the systolic pressure, and the re-inflation set value Pcl
becomes larger than PcO, and the determination of 5TIO becomes YES.

In the above embodiment, repressurization is automatically performed, but if the repressurization is insufficient, the repressurization set value or repressurization amount (
The difference between the re-pressurization set value and the initial set value) may be displayed, and the subject may perform re-pressurization according to the display, and the design can be changed as appropriate.

(g) As described in detail of the invention, the electronic blood pressure monitor of the present invention includes a pulse wave detection means for detecting a pulse wave from a subject, and a pulse wave waveform detected by the pulse wave detection means. pulse wave parameter calculating means for calculating the parameters represented by the pulse wave parameter; and a membership function memory that stores, for each of these parameters, a membership function whose variables are each parameter and the relative pressure of the air in the cuff with respect to the blood pressure value. a membership function selection means for selecting a membership function corresponding to each parameter calculated by the pulse wave parameter calculation means from membership functions stored in the membership function storage means; pressurization insufficient detection means for estimating the relative pressure by performing a predetermined logical operation on the membership function for each parameter selected by the function selection means, and detecting pressurization insufficient from the estimated relative pressure; It is characterized by being prepared.

Therefore, not only can insufficient pressurization be accurately determined after the first pressurization is completed, but also the extent of the shortage can be known, and repressurization can be completed only once. Therefore, there is less need to be careful in determining the initial set value, and it is possible to prevent the subject from determining a higher set value than necessary.

Furthermore, since insufficient pressurization is detected using pulse waves, erroneous detection of insufficient pressurization due to surrounding noise can be prevented, and the risk of causing pain or depression to the subject is reduced.

Furthermore, the need for remeasurement is reduced, improving measurement efficiency.

[Brief explanation of drawings]

FIG. 1 is a diagram showing membership functions for explaining repressurization setting value estimation processing of an electronic blood pressure monitor according to an embodiment of the present invention, and FIG. 2 is a diagram showing pulse wave parameter calculation of the electronic blood pressure monitor. 3 is a block diagram illustrating the configuration of the electronic sphygmomanometer, 4 is a flow diagram illustrating the overall operation of the sphygmomanometer, and 5 is a waveform diagram illustrating the process. Electronic [
FIG. 6 is a flowchart explaining the needle pressure pulse wave parameter calculation process, and FIG. 6 is a flowchart explaining the repressurization setting value estimation process of the electronic blood pressure monitor, FIG. 7(a), FIG. 7(b) , 7th
FIG. 7(C) and FIG. 7(d) are diagrams showing actually measured data for explaining the relationship of pulse wave amplitude, integral level, waveform width ratio, and curvature ratio with relative cuff pressure, respectively. 2: Cuff, 3: Exhaust valve, 4: Pressure pump, 5: Pressure sensor, 7: Bandpass filter, IO: MPU, 10a: Memory, Pc: Cuff pressure, p%, relative cuff pressure, Piv(t) :Pulse wave,
AMPj pulse wave amplitude value, RAV: Integral level, W■
D: Waveform width ratio, CON: Curvature ratio. Patent Applicant Tateishi Electric Co., Ltd. Agent Patent Attorney Shigeru Nakamura Figure 1 Figure 2 min Figure 3 n] Ua Figure 4 Figure 5 Figure 6 Figure 7 (a) Figure 7 (b) Figure 7 (C) (SYS) Pc' Procedural Mixing Seiseki F (Spontaneous) August 31, 1989 1999 Patent Application No. 131842 2, Title of Invention Electronic Sphygmomanometer 3, Person Making Amendment Case Relationship Patent applicant address 10 Hanazono Tsuchido-cho, Ukyo-ku, Kyoto City Name (29)
4) Tateishi Electric Co., Ltd. Representative: Yoshio Tateishi 4, Agent: ◎604 Address: 5F Kyoto Muro Building, 3-1 Mibu Kayo Gosho-cho, Nakagyo-ku, Kyoto City Voluntary amendment 7, Contents of amendment (1) Specification, page 4, 16 From the line to the 17th line [re-pressurization may be required]. ” is replaced with “
Even if the pressurization value is increased by a certain amount and pressurization is performed again, the pressure may still be insufficient or the pressure may be applied more than necessary. ” he corrected. (2) On page 8, lines 2 to 4, the phrase ``probability distribution function...is possible.'' was replaced with ``probability density distribution, which can be used to The ship function can be generated.'' (3) From line 8 to line 9 of page 8, the text "corresponds to a membership function. J" is corrected to "can be used as a membership function." (4) From page 17, line 17 to line 18, “
"Probability distribution function" should be corrected to "probability density distribution." (5) Amend Figure 1 as shown in the attached sheet 8. List of attached documents (+) Corrected drawings [Figure 1] One or more copies of Figure 1

Claims (1)

[Claims] (1) A cuff to be worn on a subject, a pressurizing means for pressurizing the air within the cuff, an exhaust means for rapidly or slowly exhausting the air within the cuff, and a pressure detector for detecting the air pressure within the cuff. a cardiovascular information detecting means for detecting cardiovascular information of the subject; and determining a blood pressure value based on the air pressure detected by the pressure detecting means and the cardiovascular information detected by the cardiovascular information detecting means. An electronic sphygmomanometer comprising: a pulse wave detecting means for detecting a pulse wave from the subject; a pulse wave parameter calculation means for calculating parameters; and a membership function storage means for storing, for each of these parameters, a membership function whose variables are each parameter and the relative pressure of the air in the cuff with respect to the blood pressure value. and membership function selection means for selecting membership functions corresponding to each parameter calculated by the pulse wave parameter calculation means from among the membership functions stored in the membership function storage means; pressurization insufficient detection means for estimating the relative pressure by performing a predetermined logical operation on the membership function for each parameter selected by the function selection means, and detecting pressurization insufficient from the estimated relative pressure; An electronic blood pressure monitor characterized by: