JPH0353935B2 - - Google Patents

Description

[Detailed description of the invention] (b) Industrial application fields This invention relates to improvements in electronic blood pressure monitors.

(b) Conventional technology Conventionally, electronic blood pressure monitors that measure blood pressure at the finger of the human body have been designed to obstruct blood flow in the blood vessels of the finger with a cuff that presses against the finger. The pulsation of changes in the deposition of blood is optically detected as a pulse wave by shining light from the pulse wave sensor installed in the cuff, and blood pressure values (systolic blood pressure value, diastolic blood pressure value, etc.) are determined based on the amplitude of this pulse wave. ) is known as a photoelectric electronic blood pressure monitor.

(C) Problems to be Solved by the Invention Since the above-mentioned conventional electronic blood pressure monitor is equipped with only a single blood pressure value determining means, the amplitude of the pulse wave detected and collected to determine the blood pressure value is There is an inconvenience that an error occurs in the determined blood pressure value when the value data contains an abnormal value due to an artifact (disturbance of the pulse wave caused by moving the arm or the like).

In addition, the same electronic blood pressure monitor can be used to measure blood pressure in the finger and arm sequentially, and compare the two values to improve measurement accuracy, or to select the desired part of the user to measure the blood pressure. If you want to use a different type of cuff, such as when you want to perform measurements, you can use a cuff that is equipped with both a photoelectric type blood pressure value determination means and a blood pressure value determination means for the vibration method, which is used in an arm blood pressure monitor. This resulted in the inconvenience of increased costs.

This invention was made in view of the above-mentioned disadvantages, and it is possible to eliminate abnormal values in pulse wave data and to measure blood pressure at different sites using different cuffs using a single blood pressure value determining means. The purpose is to provide an electronic blood pressure monitor.

(d) Means for Solving the Problems As a means for solving the above-mentioned problems, the electronic blood pressure monitor of the present invention, as shown in FIG. A pressurizing means 3 that pressurizes the cuff 1, a depressurizing means 4 that depressurizes the cuff 1 very slowly or rapidly, a pressure sensor 5 that detects the pressure of the fluid in the cuff 1 (hereinafter referred to as cuff pressure), and an output of the pressure sensor 5. A pulse wave component detection means 6 that detects the pulse wave included in the signal, a pulse wave sensor 2 that is attached to the cuff 1 and that detects the vascular pulse wave by photoelectric conversion, and a time differential of the output signal of the pulse wave sensor 2. pulse wave amplitude values of the output signals of the differentiating means 7, the pulse wave component detecting means 6, and the output signals of the differentiating means 7;
The pulse wave amplitude value calculating means 8 that calculates A _P , A _O compares these pulse wave amplitude values A _P , A _O , and when the difference between these two amplitude values is less than a predetermined value, both amplitude values A _P , A _O is determined to be normal, and normal pulse wave amplitude values A _P and
Based on the pulse wave amplitude value A _P or A _O selected by the normal value judgment and selection means 9, the blood pressure value (systolic blood pressure value/diastolic blood pressure value) _is determined from the cuff pressure P _C. The blood pressure value determining means 10 determines the blood pressure value, etc.), and the display 11 displays the blood pressure value obtained by the blood pressure value determining means.

(E) Function The function of the electronic blood pressure monitor of the present invention will be explained below based on FIG. 5a, FIG. 5b, FIG. 5c, FIG. 6a, and FIG. 6b.

5a shows the waveform of the pulse wave (hereinafter referred to as pressure pulse wave) included in the output signal of the pulse wave component detection means 6, and FIG. 5b shows the pulse wave included in the output signal of the pulse wave sensor 2. (hereinafter referred to as photoplethysmogram), and it is recognized that the waveforms are different between the two. On the other hand, Fig. 5c shows the time-differentiated photoplethysmogram (hereinafter referred to as differential photoplethysmogram).
It is recognized that the waveform is similar to that of the pressure pulse wave shown in FIG. 5a. In addition,
t in FIG. 5a, FIG. 5b, and FIG. 5c is time.

Therefore, it is inferred that there is a similar relationship between the time differential of the photoplethysmogram and the temporal change of the pressure pulse wave, and the similar relationship was confirmed by the experiment of the inventor of the present application. FIG. 6b shows normalized amplitude values of a pressure pulse wave and a differential photoplethysmogram sampled at the same period. In addition,
As before, t represents time.

Now, if an abnormality occurs due to an artifact or the like at time _t1 , the degree of influence of the abnormality on the pressure pulse wave and the degree of influence on the photoplethysmogram and the differential photoplethysm wave should be different from each other. This is because the pressure pulse wave is a change in pressure, while the photoplethysmogram is a change in blood vessel volume, and they capture different reductions. Therefore, when an abnormality occurs, different amplitude values are taken as shown with * in FIGS. 6a and 6b.

By the way, when the amplitude values of the normalized pressure pulse wave and the differential photoplethysm wave are compared and the difference between the two values becomes large, it can be estimated that an abnormality has occurred. In the electronic blood pressure monitor of the present invention, the normal value determination and selection means 9 compares the amplitude value A _P of the pressure pulse wave and the amplitude value A _O of the differential photoplethysmogram, and determines that both values A _P ,
If A _O is significantly different, it is assumed that an abnormality has occurred and is excluded from the pulse wave data for blood pressure determination, and based on the pulse wave amplitude value A _P or A _O that is considered to be a normal value. , the blood pressure value determination means 10 determines the blood pressure value based on the blood pressure value determination theory generally employed in the vibration method.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 2 to 4.

FIG. 2 shows an external perspective view of the electronic blood pressure monitor 12 according to the embodiment of the present invention. 13 is a cuff case 13b provided with an opening 13a on the front surface through which a finger is inserted;
This is a cuff formed by rolling up and storing an air bag 13c. On the inner surface of the air bag 13c, a light emitting element 14a such as an LED light emitting element that irradiates light to the inserted finger;
A pulse wave sensor 1 comprising a light receiving element 14b that receives reflected light transmitted through the skin of a finger and reflected from a blood vessel.
4 is provided.

The cuff 13 and the main body case 15 are made up of a tube 1 which is made up of a bundle of lead wires connected to the pulse wave sensor 14 and a small diameter tube connected to the air bag 13c.
6 and connector 17. On the top surface of the main body case 15, there is a display 18 consisting of an LCD display element etc. that displays blood pressure values, etc., and a power switch 1.
9. Mode switch 20 and start switch 2
1 is provided.

Next, the circuit configuration of the electronic blood pressure monitor 12 of this embodiment will be explained below with reference to FIG.

The air bag 13c of the cuff 13 includes the tube 16, the connector 17, and the conduit 2 inside the main case 15.
2a, 22b, and 22c are connected to a pressure pump 23, an exhaust valve 24 for slowly or rapidly exhausting the air in the air bag 13c, and a pressure sensor 25, respectively. The pressurizing pump 23 and exhaust valve 24 are
It is controlled by an MPU (microcomputer) 29, which will be described later.

The output signal of the pressure sensor 25 is sent to an amplifier 26.
One of its outputs is directly amplified by an analog/digital (A/D) converter 28, and the other output is amplified by a bandpass filter (BPF) for detecting pressure pulse waves.
27, are input to the A/D converter 28, converted into digital signals, and sent to the MPU 29.
be taken into account.

On the other hand, the light emitting element 14a of the pulse wave sensor 14 is
LED driver 3 that operates according to instructions from MPU29
0 and emits light, and the output of the light receiving element 14b is amplified by the amplifier 31, inputted to the A/D converter 28, converted into a digital signal, and taken into the MPU 29.

The MPU 29 has a function of controlling the pressurization pump 23 and the exhaust valve 24, receives a pressure pulse wave signal, a cuff pressure value signal, and a photoplethysmogram signal from the A/D converter 28, and performs time differentiation and calculation of the photoplethysmogram signal. Its amplitude value A _O ,
A function to calculate the amplitude value A _P of the pressure pulse wave and a cuff pressure value P _C , a function to compare the amplitude values A _O and A _P and eliminate abnormal values of the amplitude values o and A _P , and an amplitude value A _O
It also includes functions such as determining blood pressure values from _AP . In addition, the display 18, the power switch 19,
Mode switch 20 and start switch 21
is connected to this MPU29.

Next, the operation of this electronic blood pressure monitor 12 will be explained below with reference to FIG.

First, when the power switch 19 is turned on, flags FA and FB are set to zero [step (hereinafter referred to as
In the next ST2, it is determined whether or not the mode switch 20 is turned on. If it is turned on, the process proceeds to ST3 and sets the flag Fa to 1 (if FA is zero). If it is not turned on, proceed directly to ST4. The flag FA is set to zero when comparing the amplitudes of the pressure pulse wave and the differential photoplethysmogram, and is set to zero when the cuff is a vibration method cuff (regardless of finger type or arm type) that does not include the pulse wave sensor 2. 1 in some cases
is set. In ST4, start switch 21
It is determined whether or not it is turned on, and if it is turned off, the process returns to ST2 and ST2 to ST4 are repeated until the start switch 21 is turned on.

When the start switch 21 is turned on in ST4, the process proceeds to ST5, and based on the command from the MPU 29,
The pressurizing pump 23 starts, and the air bag 13 of the cuff 13
c is pressurized and expands, presses against the finger that has been inserted into the cuff 13 in advance, and stops the blood flow in the blood vessels of the finger.
In ST6, the MPU 29 reads the cuff pressure value P _C from the A/D converter 28, and in the next ST7, determines whether or not this P _C has reached a predetermined value _. , ST6 and ST7 are repeated.

In ST7, if the cuff pressure value P _C reaches the predetermined value,
The pressurizing pump 23 is stopped, the exhaust valve 24 is caused to perform slow exhaustion, and the pressure in the air bladder 13c of the cuff 13 is lowered at a constant rate (ST8). In the next ST9, a timer _T2 is started to set the sampling period for calculating the amplitude values _AP and _AO of the pressure pulse wave and the differential photoplethysmogram.

In the next ST10, in order to calculate the amplitude values A _P and A _O , in ST11, a timer T ₁ is started for setting the sampling period to collect the level values of the pressure pulse wave and the differential photoplethysm wave. Timer T
If the time-up occurs, the MPU 29 reads the pressure pulse wave level α _P from the A/D converter 28 (ST12).

In ST13, it is determined whether the value of the flag FA is zero, and if FA=0 (when comparing the differential photoplethysmogram amplitude value A _O and the pressure pulse wave amplitude value A _P ), the process proceeds to ST14, and the FA If ≠0 (when blood pressure is measured using only the pressure pulse wave amplitude value _AP ), the process directly proceeds to ST16.

In ST16, the MPU 29 reads the level α _O of the photoplethysmogram from the A/D converter 28, performs a differential operation in ST16, and calculates the level α _O ′ of the differential photoplethysmogram.
In the next ST17, it is determined whether or not the timer _T2 has timed up. ST10 to ST15 are repeated until the timer _T2 has timed up, and the amplitude values A _P and
Collect data at levels α _P and α _O ′ for calculating A _O.

If it is determined in ST16 that timer T ₂ has timed up, the process advances to ST17 and the pressure pulse wave amplitude value A _P
, the data string of the collected and stored pressure pulse wave level α _P is calculated. Next, in ST18, it is determined whether FA=0 or not. If FA≠0, the process directly proceeds to ST21; if FA=0, the process proceeds to ST19, and from the collected data string, the differential photoplethysm wave amplitude is determined. The value A _O is calculated.

In the next ST20, the amplitude values A _P and A _O are compared based on the following equation (1), and it is determined whether A _P and A _O are abnormal values.

A _P −nA _O <Ath …(1) Here, n is a constant that normalizes the amplitude value A _O ,
Ath is a preset threshold.

If the above equation (1) is not satisfied, the process returns to ST9 and the next new data string of pressure pulse wave level α _P and differential photoplethysm wave level α _O ′ is collected. If the above formula (1) is satisfied, proceed to ST21 and calculate the cuff pressure value.
Load _PC . Furthermore, in ST22, the pressure pulse wave amplitude value A _P
and the cuff pressure value P _C read in ST21 are stored in association with each other.

In the next ST23, it is determined whether the amplitude value A _P (or A _O ) has increased compared to the previous amplitude value.
If the amplitude value A _P is increasing, return to ST9,
Continue collecting data of amplitude values A _P and _AO . When the amplitude value _AP stops increasing, the process proceeds to ST24, and it is determined whether the flag FB is zero or one. Flag FB
If ≠0, proceed directly to ST28 and set the flag
If FB=0, proceed to the next ST25.

In ST25, the amplitude value A _P (or
A _{P MAX} corresponding to 0.5 times A _P MAX is extracted in _the next ST26. 5
Further extract this _AP . The cuff pressure value P _C corresponding to 5 is stored as the systolic blood pressure (SYS) value. Then, set FB to 1 (ST27).

In ST28, it is determined whether the current amplitude value A _P is less than or equal to 0.7 times the maximum value A _P MAX extracted in ST25,
If A _P > 0.7A _P MAX, return to ST9 and collect data of amplitude values A _P and A _O (however, ST25
~ST27 is not performed). On the other hand, A _P ≦0.7A _P MAX
If so, proceed to ST30 and find the amplitude value A _{P .} that is closest to 0.7 times A _P MAX. 7 and extract this A _P . 7
The blood pressure value P _C corresponding to is stored as the diastolic blood pressure value (DIA). Next, the SYS value and DIA value are displayed on the display 18 (ST30), and the exhaust valve 24 is
The air bag 13c of the cuff 13 is
Remove the air inside the chamber and complete the blood pressure measurement.

In the above embodiment, a photoelectric finger cuff is shown as the cuff 13, but a vibration method finger cuff without a pulse wave sensor or an arm cuff may also be used as the cuff. can.

In addition, in the above embodiment, there are a mode in which a differential photoplethysmogram and a pressure pulse wave are used together, and a mode in which only a pressure pulse wave is used. It can also be provided together with or in place of other modes.

(G) Effects of the Invention The electronic blood pressure monitor of the present invention includes a cuff, a pressurizing means for pressurizing the fluid in the cuff, a depressurizing means for slowly or rapidly reducing the pressure of the fluid in the cuff, and a fluid pressure monitor in the cuff. a pressure sensor that detects a pulse wave component; a pulse wave component detection means that detects a pulse wave component included in an output signal of the pressure sensor; a pulse wave sensor attached to the cuff that detects a vascular pulse wave by photoelectric conversion; A differentiating means for time-differentiating the pulse wave signal from the pulse wave sensor, and a pulse wave amplitude value A _P from the pulse wave obtained by the pulse wave component detecting means, and an amplitude value of the output signal of the differentiating means.
Pulse wave amplitude value calculation means for calculating A _O respectively;
Compare the pulse wave amplitude value A _P and the amplitude value A _O obtained by this pulse wave amplitude value calculation means, and when the difference between these two amplitude values is less than a predetermined value, both amplitude values A _P and A _O are normalized. normal value determination and selection means that determines that the pulse wave amplitude value A _P and amplitude value A _O are normal; and a pulse wave amplitude value that is selected by the normal value determination and selection means.
Since it is equipped with a blood pressure value determining means that determines a blood pressure value based on A _P or an amplitude value A _O , and a display that displays the blood pressure value obtained by this blood pressure value determining means, artifacts etc. , it has the advantage of being able to effectively prevent measurement errors, and it also has the advantage of being able to arbitrarily select and use different types of cuffs, ie, cuffs with a pulse wave sensor and cuffs for vibration methods.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the concept of this invention, Figure 2 is a diagram explaining the concept of this invention.
3 is a circuit block diagram of the electronic blood pressure monitor, FIG. 4 is a diagram explaining the operation of the electronic blood pressure monitor, and FIG. 5a is a diagram showing the waveform of the pressure pulse wave, FIG. 5b is a diagram showing the waveform of the photoplethysmogram, FIG. 5c is a diagram showing the time differential waveform of the pressure pulse wave, and FIG. FIG. 6a is a diagram showing the change in photoplethysmogram amplitude value over time, and FIG. 6b is
FIG. 3 is a diagram showing changes over time in the amplitude value of the time derivative of a photoplethysmogram. 1, 13: Cuff, 2, 14: Pulse wave sensor, 3:
Pressurization means, 23: Pressure pump, 4: Pressure reduction means, 2
4: exhaust valve, 5, 25: pressure sensor, 6: pulse wave component detection means, 27: band filter, 7: differentiation means, 8: pulse wave amplitude value calculation means, 9: normal value determination and selection means, 10: blood pressure Value determining means, 11, 18: Display device.

Claims (1)

[Claims] 1. A cuff, a pressurizing means for pressurizing the fluid in the cuff, a depressurizing means for slowly or rapidly decompressing the fluid in the cuff, a pressure sensor for detecting the fluid pressure in the cuff, and an output signal of this pressure sensor. a pulse wave component detection means for detecting a pulse wave component contained in the cuff; a pulse wave sensor attached to the cuff that detects a vascular pulse wave by photoelectric conversion; a pulse wave amplitude value calculating means for calculating a pulse wave amplitude value A _P of the pulse wave obtained by the pulse wave component detecting means and an amplitude value A _O of the signal output from the differentiating means; The pulse wave amplitude value A _P and the amplitude value A _O obtained by the wave amplitude value calculation means are compared, and when the difference between these two amplitude values is less than a predetermined value, both the amplitude values A _P and A _O are determined to be normal. It is determined that there is
A normal value determination and selection means for selecting normal pulse wave amplitude values A _P and amplitude values _AO , and a blood pressure value based on the pulse wave amplitude values A _P or amplitude values _AO selected by the normal value determination and selection means. An electronic sphygmomanometer comprising a blood pressure value determining means and a display device displaying the blood pressure value obtained by the blood pressure value determining means.