JPH10151118A - Electronic blood pressure gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce infrlence of an error in reference blood pressure more than when single reference blood pressure is used, and measure blood pressure with higher accuracy by calculating and storing new reference blood pressure by using separately inputted plural reference blood pressures. SOLUTION: An electronic blood pressure gauge 10 has a pulse wave detecting part 1 and an electrocardiogram detecting part 3, and these detecting signals are inputted to a CPU 6 through amplifiers 2 and 4 and an A/D converter 5, and a found result is displayed on a display part 7. A communication part 8 is provided to perform transmission and reception between it and an external blood pressure measuring means 20 to measure blood pressure on the basis of a separate blood pressure measuring method. Input of reference blood pressure is demanded from the CPU 6, and the reference blood pressure detected by the blood pressure detecting means 20 on the basis of its indication, is read in the CPU 6 as calibrating blood pressure. Input of this reference blood pressure is performed three times, and reference blood pressures equivalent to three times are additively averaged, and it is stored. Parameter values are also additively averaged, and afterwards, only a characteristic quantity of an electrocardiogram-pulse wave signal is measured, and a blood pressure value is calculated from the reference blood pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic sphygmomanometer requiring calibration using another blood pressure measuring device, and more particularly to an improvement in the calibration.

[0002]

2. Description of the Related Art There is an electronic sphygmomanometer based on the principle and method of measuring only a change in blood pressure instead of directly measuring an absolute value of blood pressure. For example, a sphygmomanometer that captures the speed at which a pulse wave travels in an artery (pulse wave propagation speed), heart rate, characteristic amounts of a pulse wave waveform, and converts them into parameters, converts the change into a change in blood pressure, and displays the change. There is. In principle, this type of system can calculate the blood pressure from one pulse of electrocardiogram or pulse wave signal, thus realizing a sphygmomanometer that performs continuous blood pressure measurement non-invasively or measures in a very short time. There are features that can be done.

[0003] On the other hand, since these parameters rarely have a close relationship with the blood pressure value because there are individual differences in these parameters, this type of sphygmomanometer uses:
The relative blood pressure, that is, only the blood pressure fluctuation value can be calculated using the relationship between the fluctuation values of the parameter and the blood pressure. This is conceptually illustrated as shown in FIG. In FIG. 5, the origin of the graph is a reference point, and both the blood pressure fluctuation value on the horizontal axis and the parameter fluctuation value on the vertical axis are represented by relative values from the reference point. That is, with a certain point as a reference, an increase or decrease (relative change) from the reference value correlates with a relative change in blood pressure.

Therefore, it is necessary to input and store the absolute value of blood pressure (reference blood pressure) obtained by other blood pressure measuring means in the blood pressure monitor by any method (manual input or communication means) Is simply called calibration). Then, in the measurement performed after the calibration, the absolute value is indirectly obtained by adding the blood pressure fluctuation amount and the reference blood pressure value. This can be summarized as follows. 1) A feature amount is detected, and a difference from the reference value is calculated as a feature amount change amount. 2) The blood pressure change amount is calculated from the relationship between the parameter change amount and the blood pressure change amount stored in advance. 3) The reference blood pressure value stored at the time of calibration is added to the blood pressure change amount obtained in (2) to obtain an absolute value of blood pressure.

[0005]

The following three points can be considered as error factors of this type of blood pressure monitor. There is an individual difference in the relationship between the parameter change amount and the blood pressure change amount (inclination of distribution), and an error caused by not completely one-to-one correspondence. Measurement and calculation errors on parameters. Calibration sphygmomanometer error.

[0006] Among these errors, the slope of the relationship between the blood pressure and the parameter variation is increased by increasing the types of parameters and using a calculation formula integrating a plurality of relational expressions, or by performing calibration by varying the blood pressure. A method has been devised, such as directly requesting. The error can be dealt with by improving the measurement accuracy by obtaining the parameters for the waveforms of a plurality of beats and obtaining the average value.

However, since the error is a problem specific to the calibration sphygmomanometer, it has not been solved so far. This calibration sphygmomanometer is generally assumed to be a commercially available cuff type sphygmomanometer, but its error range may be up to ± 20 mmHg depending on conditions.
Also, if body movement occurs due to inexperience of the user or the like, the error may be larger.

In this case, since a reference blood pressure value including an error is input to this type of sphygmomanometer, the error always appears as it is in the measurement result every time subsequent measurement is performed. This is because this type of sphygmomanometer calculates a measurement value by adding a reference blood pressure value to a blood pressure fluctuation value obtained each time. Accordingly, the present invention has been made in view of such a problem, and an object of the present invention is to provide an electronic sphygmomanometer that eliminates an error in a reference blood pressure value and obtains a highly accurate measurement value.

[0009]

In order to achieve the above object, an electronic sphygmomanometer according to claim 1 of the present invention comprises: a pulse wave detecting means for detecting a pulsating component from a blood vessel obtained in synchronization with a heartbeat; A waveform feature value calculating means for quantifying a waveform feature value for a part or a plurality of parts of the pulse wave, and a reference feature value for storing an absolute value of the waveform feature value obtained by the pulse wave detecting means as a reference feature value A storage unit, a waveform feature change amount calculating unit that calculates a change in the waveform feature amount by subtracting the waveform feature amount obtained from the waveform feature amount calculation unit and the reference feature amount, and a waveform feature change amount and a blood pressure. A blood pressure change calculating means for calculating a blood pressure change by associating the change with a change; and a blood pressure value obtained by the blood pressure measuring means for performing blood pressure measurement based on a blood pressure measuring method other than the above, as a standard blood pressure input and storage. Storage means for obtaining the reference characteristic amount in the measurement at the beginning of use or during use, associating the reference characteristic amount with the reference blood pressure obtained by the reference blood pressure input / storage means, and performing the measurement performed thereafter. Detecting only the waveform characteristic change amount obtained from the waveform characteristic change amount calculation means, and calculating the blood pressure fluctuation by inputting the waveform characteristic change amount to the blood pressure fluctuation calculation means; In an electronic sphygmomanometer in which a blood pressure value is calculated by adding a reference blood pressure stored in a storage means, the reference blood pressure input / storage means can sequentially input a plurality of reference blood pressure values, and A new reference blood pressure calculated using a plurality of reference blood pressures is stored.

In this sphygmomanometer, a new reference blood pressure is calculated and stored using a plurality of separately input reference blood pressures.
As compared with the case where one reference blood pressure is used, the influence of the error of the reference blood pressure is reduced, and more accurate blood pressure measurement can be performed. The electronic sphygmomanometer according to claim 4 is a pulse wave detecting means for detecting a pulsating component from a blood vessel obtained in synchronization with a heartbeat, and digitizes a waveform feature value for a part or a plurality of parts of the pulse wave. A waveform feature value calculation unit, a reference feature value storage unit that stores an absolute value of the waveform feature value obtained by the pulse wave detection unit as a reference feature value, and a waveform feature value obtained from the waveform feature value calculation unit. A waveform feature change amount calculating unit that calculates a change in a waveform feature amount by subtracting the reference feature amount, and a blood pressure change calculating unit that calculates a blood pressure change by associating the waveform feature change amount with a change in blood pressure,
Reference blood pressure input / storage means for inputting and storing a blood pressure value obtained by a blood pressure measurement means for performing blood pressure measurement based on a blood pressure measurement method other than the above as a reference blood pressure, wherein the reference characteristic is used in measurement at the beginning of use or during use. In addition to obtaining the amount, the reference blood pressure obtained by the reference blood pressure input / storage means is made to correspond to this reference characteristic amount, and in the measurement performed thereafter, only the waveform characteristic change amount obtained from the waveform characteristic change amount calculation means is used. Detecting and calculating the blood pressure fluctuation by inputting the waveform characteristic change amount to the blood pressure fluctuation calculating means, and adding the reference blood pressure stored in the reference blood pressure input / storage means to the blood pressure fluctuation, thereby obtaining the blood pressure value. In the electronic sphygmomanometer which calculates the reference measurement, the reference measurement requesting the user to perform the reference measurement so that the reference measurement is performed at least twice or more. It includes a request unit, the reference blood pressure input and storage means, and to store the new reference blood pressure calculated using the plurality of reference blood pressure entered at the request of the reference measurement request means.

In this sphygmomanometer, a new reference blood pressure is calculated and stored using a plurality of separately input reference blood pressures.
As compared with the case where one reference blood pressure is used, the influence of the error of the reference blood pressure is reduced, and more accurate blood pressure measurement can be performed. In addition, since the plurality of reference blood pressures are requested to the user by the reference measurement requesting means, it is easy to determine whether or not the reference measurement is required.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a block diagram showing a device configuration of the electronic sphygmomanometer according to the embodiment. The electronic sphygmomanometer 10 includes a pulse wave detecting section 1, an amplifier 2 for amplifying an output of the pulse wave detecting section 1, an electrocardiographic detecting section 3, and an electrocardiographic detecting section 3.
, An A / D converter 5 and a CP
A communication unit (communication) for transmitting and receiving between a U (microcomputer) 6, a display unit 7, and an external blood pressure measurement unit (for example, an electronic sphygmomanometer) 20 for performing blood pressure measurement based on another blood pressure measurement method Means 8). Another blood pressure measurement means 20 is connected to the electronic sphygmomanometer 10 via the communication unit 8.

The pulse wave detector 1 continuously detects a pulsation component (pulse wave) resulting from a change in arterial volume at a measurement site such as a fingertip. The electrocardiogram detection unit 3 attaches an electrode to an arbitrary part of the body surface and detects a potential change as an electrocardiogram signal. The pulse wave and the electrocardiographic signal are input to the A / D converter 5 via the amplifiers 2 and 4, respectively, are converted into digital signals, and are input to the CPU 6. In CPU 6,
Waveform processing, blood pressure calculation processing, and the like, which will be described later, are performed, and the result (blood pressure value) is displayed on the display unit 7.

The overall operation of the electronic sphygmomanometer 10 will be described with reference to the general flow charts of FIGS.
However, various parameters used for blood pressure calculation can be considered,
Here, a case will be described in which some of the most widely known pulse wave propagation velocities and features on the pulse wave waveform are used. But,
It is also possible to calculate only the waveform of the pulse wave, and the present invention does not particularly limit the feature amount.

The overall operation is an operation during calibration (flow chart in FIG. 2) and an operation after calibration (normal measurement operation, flow chart in FIG. 3).
, And will be described below in order. <Calibration Operation> In the flowchart of FIG. 2, the processing of steps (hereinafter abbreviated as ST) 1 to 3 is repeatedly executed each time the pulse wave signal and the electrocardiographic signal are read into the CPU 6.
First, in ST1 and ST2, the pulse wave / electrocardiographic signal is A / D converted at a sampling cycle of, for example, 5 msec, and read into the CPU 6. In ST3, a pulse wave is recognized for each pulse in a series of pulse wave signals, and the time of the starting point is stored (breakpoint). Details of this recognition processing will be described later.

In ST4, the R wave of the electrocardiogram waveform (electrocardiogram signal) fetched by the electrocardiogram detecting section 3 is detected, and its appearance time is stored. The R-wave is a peak-like feature point that appears in the electrocardiogram signal every beat, and its detection method is widely applied in the field of electrocardiogram, and is not particularly novel, so a detailed description is omitted here. . In ST5, it is determined whether or not a break point is detected at that time in the break processing. If detected, the process proceeds to the following ST6 and subsequent steps. If not, the processing of ST1 to ST4 is repeated. .

In ST6, parameters relating to the pulse wave waveform and the pulse wave propagation velocity are calculated for the beat at which the breakpoint is detected, and stored in the storage means. Details of this processing will be described later. When the parameter storage process of ST6 is performed,
Next, in ST7, the user is requested to input a reference blood pressure. In this embodiment, the display unit 7 of the electronic sphygmomanometer 10
A notification indicating that the reference measurement is required is displayed on the display or a sound of a buzzer, and an instruction signal indicating that the reference measurement is required is output from the communication unit 8 to the external blood pressure measurement unit 20. The instruction includes a display on the display unit of the blood pressure measurement unit 20, a sound by a buzzer, and the like. The user measures the blood pressure value serving as the reference blood pressure with the blood pressure measuring means 20 based on the instruction. The reference blood pressure obtained by the blood pressure measuring means 20 is input to the CPU 6 via the communication unit 8 as a calibration blood pressure. Instead of inputting the reference blood pressure via the communication unit 8, the user may manually input the reference blood pressure measured by the blood pressure measuring means directly to the electronic sphygmomanometer 10. Also in this case, the request for the reference measurement may be notified by a display on the display unit 7 or a sound from a buzzer.

When the reference blood pressure is input, it is recognized in the next ST8. Each time the reference blood pressure is entered,
In ST9, it is determined whether or not the input of the reference blood pressure has been performed three times. When the reference blood pressure is input less than three times, the user is notified that the next reference measurement is required, as described above, and the reference blood pressure is input. Then, returning to ST1, the next measurement is further performed, and the processing up to ST8 is repeated to input the reference blood pressure corresponding thereto.

When the reference blood pressure input is executed three times, ST9 is executed.
To ST10. In ST10, the three reference blood pressures are added and averaged, and the average value is stored in the storage means (ST11). Instead of the reference blood pressure averaging process in ST10, for example, an averaging of three reference blood pressure values is obtained, and the relative allowable range of the reference blood pressure value calculated based on the averaging value (for example, ± 10% of the average value) ), An average of only the reference blood pressure values within the allowable range may be obtained again, and the average value may be stored in the storage means.

Next, in ST12, addition averaging is performed on the parameter values, and the resulting averaged parameter is stored (ST13). Finally, the display unit 7 displays that a series of calibration operations has been completed (ST1).
4) Complete all operations. <Operation after calibration> In the operation after calibration (normal measurement operation), only the feature of the electrocardiogram / pulse wave signal is measured, and the blood pressure value is calculated based on the reference blood pressure and the reference feature obtained at the time of calibration. Do.

In the flow chart of FIG.
The processing contents from ST21 to ST25 relating to knowledge are described above.
The processing is the same as the processing of ST1 to ST5 in the flowchart of FIG.
The description is omitted. In ST26, a breakpoint is detected.
Parameters related to pulse waveform and pulse wave velocity
Calculate the meter and calculate the difference from the reference feature value stored during calibration.
To obtain a parameter difference value (ST27). here,
Since not only one parameter is used,
Data difference value to S₁, S_Two, ..., S_n(N is the number)
You. In ST28, a coefficient by which each parameter is multiplied (parameter
Data coefficient) to K₁, K_Two, ..., k _nThen, the next predetermined
Equation, BP = K₁・ P₁+ K_Two・ P_Two+ ... + K_n・ P_n+
BP_s To calculate the blood pressure value. Where BP_sIs the reference blood pressure
Value. Finally, in ST29, the blood pressure calculation result (blood pressure
Value) is displayed, and all processing is completed.

The separation process between ST5 and ST25 in the flowcharts of FIGS. 2 and 3 will be described. Although various types of pulse wave separation processing can be considered, the most common method is shown in FIG.
As shown in (1), a pulse wave signal (a series of pulse wave data) is passed through a high-pass filter (for example, a cutoff frequency of 1 Hz) that allows only a relatively high frequency component to pass therethrough, and the intersection of the output waveform with the baseline is set to the start of each beat. This can be realized by setting the start point, that is, the break point.

A description will be given of the waveform parameter calculation process in ST26 in the flowchart of FIG. Although various waveform features related to the blood pressure fluctuation can be considered, here, the calculation process will be described using two types of parameters as representative examples. First,
The most widely used parameter, pulse wave velocity (P
WV) will be described. The PWV is obtained from the time difference between the R wave appearance time and the pulse wave appearance time at the peripheral part (for example, the fingertip). The R wave is seen when the heart starts pumping blood, and its appearance time can be approximately the time when the pulse wave appears near the heart, and this and the pulse wave in the peripheral part such as a finger. By calculating the difference from the detection time, that is, the time difference from the detection of the R wave of the electrocardiogram signal to the detection of the breakpoint of the pulse wave in the peripheral part, the time required for the pulse wave to propagate from the heart to the peripheral part is calculated. I can do it. Since the distance between the heart and a specific peripheral portion can be constant in an individual, the reciprocal of the pulse wave propagation time is an amount proportional to the pulse wave propagation velocity.

As parameters other than the PWV, the following features on the pulse waveform are considered to indicate changes in the cardiovascular system, and are considered to change when blood pressure changes. (1) Heart rate: can be calculated as the reciprocal of the time interval between the start point of the R wave or the pulse wave. (2) Rise time: the time difference between the pulse wave starting point and the peak point of each pulse. (3) Rise / fall slope ratio: The maximum value of the rising speed of the signal between the starting point and the peak point and the minimum value of the falling speed of the signal between the peak point and the starting point of the next beat. ratio.

In this embodiment, the personal sphygmomanometer is used. However, when there are a plurality of subjects, the individual I
The reference blood pressure value may be stored together with the D number, and the reference blood pressure value may be read using the personal ID number at the time of measurement. In addition, the parameter coefficient used for calculating the blood pressure may be optimally corrected according to the blood pressure fluctuation factor (during exercise, during cold weather, etc.). The corrected parameter coefficients may be stored for each factor in a storage means (ROM) incorporated in the CPU 6 together with the computer program, and may be selected according to the blood pressure variation factor.

[0026]

As described above, according to the electronic sphygmomanometer of claim 1 (and claims 2 and 3), a new reference blood pressure is calculated and stored using a plurality of separately input reference blood pressures. Therefore, as compared with the case where one reference blood pressure is used, the influence of the error of the reference blood pressure is reduced, and more accurate blood pressure measurement can be performed.

According to the electronic sphygmomanometer of claim 4 (and claims 5, 6, and 7), a new reference blood pressure is calculated and stored using a plurality of separately input reference blood pressures. The effect of the error of the reference blood pressure is reduced as compared with the case of using, and more accurate blood pressure measurement can be performed.
In addition, since the plurality of reference blood pressures are requested to the user by the reference measurement requesting means, it is easy to determine whether or not the reference measurement is required.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an electronic sphygmomanometer according to one embodiment.

FIG. 2 is a flowchart illustrating an operation during calibration in the overall operation of the electronic sphygmomanometer according to the embodiment.

FIG. 3 is a flowchart illustrating a post-calibration operation in the overall operation of the electronic sphygmomanometer of the embodiment.

FIG. 4 is a waveform chart for explaining pulse wave division in the overall operation of the electronic sphygmomanometer of the embodiment.

FIG. 5 is a graph showing a correlation between a blood pressure change and a parameter change.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulse-wave detection part 2, 4 Amplifier 3 Electrocardiogram detection part 5 A / D converter 6 CPU 7 Display part 8 Communication part (communication means) 10 Electronic sphygmomanometer 20 Blood pressure measurement means

Claims (7)

[Claims] 1. A pulse wave detecting means for detecting a pulsating component from a blood vessel obtained in synchronization with a heartbeat, and a waveform characteristic amount calculating means for quantifying a waveform characteristic amount for a part or a plurality of parts of the pulse wave. Reference feature value storage means for storing the absolute value of the waveform feature value obtained by the pulse wave detection means as a reference feature value;
A waveform feature change amount calculating unit that calculates a change in a waveform feature amount by subtracting the waveform feature amount obtained from the waveform feature amount calculating unit and the reference feature amount, and associates the waveform feature change amount with a change in blood pressure. Blood pressure fluctuation calculating means for calculating the blood pressure fluctuation, and a reference blood pressure input / storage means for inputting and storing a blood pressure value obtained by the blood pressure measuring means for performing blood pressure measurement based on a blood pressure measurement method other than the above as a reference blood pressure. In the measurement at the beginning of use or during use, the reference characteristic amount is obtained, and the reference characteristic amount is associated with the reference blood pressure obtained by the reference blood pressure input / storage means. By detecting only the waveform characteristic change amount obtained from the change amount calculation means and inputting the waveform characteristic change amount to the blood pressure fluctuation calculation means, the blood pressure change is calculated. The reference blood pressure input /
An electronic sphygmomanometer in which a blood pressure value is calculated by adding a reference blood pressure stored in a storage means, wherein the reference blood pressure input / storage means can sequentially input a plurality of reference blood pressure values. An electronic sphygmomanometer characterized by storing a new reference blood pressure calculated using the reference blood pressure. 2. The electronic sphygmomanometer according to claim 1, wherein the reference blood pressure input / storage means calculates a new reference blood pressure using an average of a plurality of input reference blood pressure values. 3. The reference blood pressure input / storage means calculates an average value of a plurality of input reference blood pressure values, sets an allowable range of the reference blood pressure input value calculated based on the average value, and sets the allowable range. 3. The electronic sphygmomanometer according to claim 2, wherein the averaging is performed using the reference blood pressure input value within the range. 4. A pulse wave detecting means for detecting a pulsating component from a blood vessel obtained in synchronization with a heartbeat, and a waveform characteristic amount calculating means for quantifying a waveform characteristic amount for a part or a plurality of parts of the pulse wave. Reference feature value storage means for storing the absolute value of the waveform feature value obtained by the pulse wave detection means as a reference feature value;
A waveform feature change amount calculating unit that calculates a change in a waveform feature amount by subtracting the waveform feature amount obtained from the waveform feature amount calculating unit and the reference feature amount, and associates the waveform feature change amount with a change in blood pressure. Blood pressure fluctuation calculating means for calculating the blood pressure fluctuation, and a reference blood pressure input / storage means for inputting and storing a blood pressure value obtained by the blood pressure measuring means for performing blood pressure measurement based on a blood pressure measurement method other than the above as a reference blood pressure. In the measurement at the beginning of use or during use, the reference characteristic amount is obtained, and the reference characteristic amount is associated with the reference blood pressure obtained by the reference blood pressure input / storage means. By detecting only the waveform characteristic change amount obtained from the change amount calculation means and inputting the waveform characteristic change amount to the blood pressure fluctuation calculation means, the blood pressure change is calculated. The reference blood pressure input /
An electronic sphygmomanometer that calculates a blood pressure value by adding a reference blood pressure stored in a storage unit, wherein a reference measurement request for requesting a user to perform the reference measurement so that the reference measurement is performed at least twice or more. An electronic sphygmomanometer, comprising: means, wherein the reference blood pressure input / storage means stores a new reference blood pressure calculated using a plurality of reference blood pressures input in response to a request from the reference measurement requesting means. 5. A communication system for transmitting and receiving data to and from the blood pressure measurement means, wherein the reference measurement request means requests a user to perform reference measurement, and the communication means transmits the reference measurement to the blood pressure measurement means. The electronic sphygmomanometer according to claim 4, wherein an instruction signal for requesting is output. 6. The reference blood pressure input / storage means obtains an average of a plurality of input reference blood pressures and waveform feature amounts associated therewith, and stores them as a representative reference blood pressure and a representative waveform feature amount. 5. The method according to claim 4, wherein
Electronic blood pressure monitor as described. 7. The reference blood pressure input / storage means obtains an average value of each of a plurality of input reference blood pressures and waveform feature amounts associated therewith, and calculates a reference blood pressure and a calculated reference blood pressure based on the average values. 7. The electronic sphygmomanometer according to claim 6, wherein an allowable range of the waveform feature amount is set, and the averaging is performed using the reference blood pressure and the waveform feature amount within the allowable range.