JPS63311933A - Electronic hemomanometer - Google Patents

Abstract

PURPOSE:To obtain an electronic hemomanometer capable of performing accurate measurement, by correcting the blood pressure value determined by a blood pressure determining means on the basis of the preliminarily stored function showing the relation between the cuff pressure detected by a pressure sensor and the real oppressive force to the artery. CONSTITUTION:When a start switch 6 is turned ON, a motor driving circuit 25 is operated under the instruction from of an MPU 12 and a pump motor 26 is rotated to pressurize a finger cuff 2 and, when cuff pressure reaches 170mmHg, the pump motor 26 is stopped and, when a pulse wave is detected, the air pressure of a pneumatic system is gradually released by a slow speed discharge valve 29. In this process, the max. and min. pressures are determined on the basis of cuff pressure and pulse wave amplitude successively taken-in timewise. The cuff pressure Pc and oppressive force Pa have the relation of Pa=kXPc (k 0.9). The determined blood pressure value Pc displayed by adding correction become Pd=k.Pc. When measurement is finished, a valve 28 is opened to transfer to rapid discharge and a light emitting element 15 is puts out and a corrected blood pressure value is displayed on a display device 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an electronic blood pressure monitor, and particularly to an electronic blood pressure monitor that is designed to improve measurement accuracy.

(B) Conventional technology In general, an electronic finger blood pressure monitor includes a substantially cylindrical cuff for compressing the finger, an air pressure supply means such as a motor pump that supplies air pressure to the cuff, and a gradual adjustment of the air pressure to the cuff. It consists of an air pressure adjustment means such as a slow exhaust valve that changes the air pressure, a pressure sensor that detects the pressure in the cuff, a light emitting element, and a light receiving element. a photoelectric sensor that receives light from the cuff; a pulse wave extraction means that extracts a pulse wave component from the output of the light receiving element during the process of changing the air pressure of the cuff; The blood pressure determining means determines the blood pressure based on the pulse wave information stored in the blood pressure, and the display device displays the determined blood pressure value.

When measuring blood pressure with this electronic finger sphygmomanometer, with the finger inserted through the cuff, the cuff is pressurized using the air pressure supply means to compress the finger and stop blood flow, and then the cuff pressure is gradually adjusted using the air pressure adjustment means. During the slow decompression process, the cuff pressure is continuously detected by a pressure sensor, and a pulse wave amplitude data string is obtained by a photoelectric sensor and a pulse wave extraction means, and a predetermined algorithm is applied to this pulse wave amplitude data string. The blood pressure value is determined by referring to the cuff pressure and displayed on the display.

(c) Problems to be solved by the invention Whether it is the above-mentioned electronic finger blood pressure monitor or electronic blood pressure monitor for arm, a sound sensor or a pulse wave sensor is used to detect Korotkoff (K) sound as blood vessel information. Conventional electronic blood pressure monitors that compress the artery with a cuff, even those equipped with a pulse wave sensor that detects the blood pressure, detect the internal pressure of the cuff with a pressure sensor, and the cuff pressure is equal to the compression force of the artery. Blood pressure is determined as follows. Strictly speaking, however, since the width of the cuff is constant, as the cuff pressure increases, the compression force becomes weaker, and the relationship between cuff pressure and compression force is as shown in the solid line in Figure 1. = Compressive force, which deviates from the ideal characteristics shown by the broken line.

Therefore, with conventional electronic blood pressure monitors, there was a problem in that blood pressure was measured at a high level in people with high blood pressure.

An object of the present invention is to provide an electronic blood pressure monitor that can alleviate the above-mentioned conventional problems and perform accurate measurements.

(d) Means and operation for solving the problems The electronic blood pressure monitor of the present invention includes a cuff (2) for compressing an artery, an air pressure supply means (26) for supplying air pressure to the cuff,
an air pressure adjusting means for gradually changing the air pressure of the cuff (
29; and a pressure sensor (23) that detects the pressure of the cuff.
), and blood vessel information extraction means (15, 16, 19, 20,
21), blood pressure determination means (12, 5T22) for determining blood pressure based on the cuff pressure detected by the pressure sensor and blood vessel information extracted by the blood vessel information extraction means, and displaying the determined blood pressure value. function storage means (12) for storing in advance a function indicating a correlation between the cuff pressure detected by the pressure sensor and the true compressive force on the artery; and a display device (4) for determining the blood pressure. blood pressure value correction means (12, 5T23) for correcting the blood pressure value determined by the means by the function;
) to display corrected blood pressure values.

In this electronic sphygmomanometer, blood pressure determination processing is performed using cuff pressure and blood vessel information such as the K sound or pulse wave, as in conventional electronic sphygmomanometers. However, when blood pressure is high, the compression force becomes weaker than the cuff pressure, so the blood pressure determination value becomes higher. However, since a function indicating the relationship between cuff pressure and compression force is stored in advance, the blood pressure determination value is corrected using this function, and the corrected blood pressure value is displayed. Therefore, correct blood pressure is measured.

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

FIG. 2 is an external perspective view of an electronic finger blood pressure monitor showing an embodiment of the present invention. In the figure, a finger cuff 2 is attached to a main body case 1, and the finger cuff 2 is attached so that it can be opened and closed by a predetermined angle about a point 2a as a fulcrum.

When the finger cuff button 3 is operated, the tip end 2b of the finger cuff 2 separates from the main case 1 as shown in the figure, making it easier to insert a long finger into the finger cuff 2. On the surface of the main body case 1, a display 4,
It is equipped with a power switch 5 and a start switch 6. Inside the main body case 1, an electronic circuit section, a pump and a motor for driving the pump, a power source battery, etc., which will be described later, are housed.

FIG. 3 is a circuit block diagram of the electronic finger blood pressure monitor according to the embodiment. When the power switch 5 is turned on, the power supply voltage is supplied from the power supply circuit 11 to the MPU 12 and other electronic circuit sections, and the motor drive circuit 25 is operated as required under the commands of the MPU 12. , pump motor 26
Rotate to pressurize finger cuff 2, and if necessary, press MP
The rapid exhaust valve drive circuit 27 is driven under the command of U12, and the valve 28 is opened so that the pressure in the finger cuff 2 can be rapidly exhausted. Furthermore, the air pressure in the air system is gradually exhausted by the slow exhaust valve 29, and the pulse wave is measured during this slow pressure reduction process.

The MPU 12 outputs a data indicating the lighting level of the light emitting element 15.
A digital value is output, converted to an analog value by the D/A converter 13, and a predetermined voltage is input to the LED drive circuit 14, and the LED
The D drive circuit 14 is operated to light the light emitting element 15. The pressure in the finger cuff 2 is detected by a semiconductor pressure sensor 23, and an amplifier circuit 24 and an A/D converter 2
2, the data is taken into the MPUI 2 and stored. On the other hand, the output of the light receiving element 16 of the photoelectric sensor is
, a filter circuit 20, an amplifier circuit 21, and an A/D converter 22, or directly through the A/D converter 22. The output of the light receiving element 16 directly passes through the A/D converter 22 to the MP
The reason why the signal is taken into U12 is to obtain the DC component of the output of the light receiving element 16, and the MPU 12 receives this DC component and switches the lighting level of the light emitting element 15 according to the value. On the other hand, the output of the light receiving element 18 for finger detection is also
It is now being incorporated into 2.

The MPU 12 has a function of determining blood pressures such as systolic blood pressure and diastolic blood pressure based on the cuff pressure and pulse wave amplitude memorized which are taken in time sequentially during the slow evacuation process.

Further, the cuff pressure PC and the compression force P (the pressure at which the blood vessel is pressed from the outside) have the following relationship, as illustrated in FIG. 1: P=kxPc. However, kζ0.9° However, this constant is determined by the width, structure, and material of the cuff, and is actually set to an appropriate value depending on the type and model of the cuff used.

From the above relationship, the determined blood pressure value PC and the corrected blood pressure value P4 to be displayed become P, = -PC.

The MPU 12 calculates the function f (mp) = kXBP (Bp' determined blood pressure value) from the relationship between the cuff pressure Pc and the compression force P1.
is stored in memory in advance. And the MPU 12 is
It has a function of correcting the determined blood pressure value using the function and outputting the corrected blood pressure value. The corrected blood pressure value is displayed on the display (LCD) 4.

Next, the operation of measuring blood pressure using the digital finger sphygmomanometer according to the above embodiment will be described.

First, as shown in FIG. 2, the button 3 is operated to open the finger cuff 2 from the main body as shown, and, for example, the index finger is inserted into the finger cuff 2 as shown. In this state, turn on the power switch 5.

When the power switch 5 is turned on, the processing operation of the MPU 12 starts, and as shown in FIG.
(referred to as T)1]. Subsequently, all segments of the display 4 are turned off, and after checking the operation of the display 4 (Sr2), the heart (9) mark on the display 4 is turned on (Sr3). When this heart mark is lit, it indicates that the preparation of the electronic circuit section of the meter is completed, and the measurer then turns on the start switch 6 (Sr4). As a result, Sr4's determination as to whether the start switch was pressed becomes YES.
Subsequently, the heart mark on display 4 is turned off (Sr5)
. Next, it is determined whether a finger is inserted (Sr1
). This determination is made when the light emitting element 15 is turned on and the light receiving element 1 is turned on.
The determination is made based on whether or not the light entering 8 is blocked. In other words, when the measurer inserts his or her finger into the finger cuff 2, the light emitting element 1
Since the light from 5 is blocked by the finger, finger insertion is detected by this. In the state where the finger is inserted as shown in FIG. 2, this determination becomes YES and an upward arrow is lit on the display 4 (Sr7). This upward arrow is a display indicating the start of the pressurizing operation, and at the same time the valve 28 is closed (Sr8). In addition, the motor drive circuit 25
to start rotating the pump motor 26 (
Sr9), and set the maximum pressurizing time (ST10
). This pressurization maximum time is for setting the time required for pressurization. After the pressurization operation starts, 5 TII
Then, it is determined whether or not the finger has been inserted again. If the finger is still inserted, the pressurization is continued. Then, it is determined whether the cuff pressure is 170 mmHg or more (ST12). , cuff pressure is 170 mmH
If the initial pressure is not higher than gmmg, the judgment will be NO.
Then, the process moves to 5T13, and it is determined whether the maximum pressurization time is over. If the maximum pressurization time has not exceeded, the process returns to 5TII, that is, the pressurization operation continues as it is. This 170 mm is what determines whether the cuff pressure has reached 170 mmHg or higher in 5T12.
This is because Hg is set as the pressure target value.

When the cuff pressure reaches 170 numHg, the determination at 5T12 becomes YES, and the pump motor 26 is stopped (5T14), and the upward arrow on the display 4 is turned off (ST
15). This completes pressurization, and the finger cuff 2 is connected to the slow exhaust valve 2.
From 9, enter slow exhaust. Thereafter, to detect the pulse wave, turn on the light emitting element 15 (ST'16) and wait for 2 seconds (ST'16).
T17), then it is determined whether a pulse wave has been detected (ST
18). When the pulse wave is not detected, the cuff pressure is 20
Check whether it is below mmHg (ST25)
, 5T18 pulse wave detection processing is performed until it becomes 20 mmHg or less. If a pulse wave is still not detected even after the cuff pressure has decreased to 20 mm and 11 g, it is assumed that there is an abnormality and E (error) is displayed on the display 4 (Sr26).
Move on to 8. When a pulse wave is detected at 5T18, the heart mark is lit for 0.2 seconds at 5T19, and the pulse wave amplitude at that time is memorized. 5T21)
, repeat the pulse wave detection process until the pulse waves are aligned. Once the data is complete,
That is, if the determination at 5T21 is YES, the blood pressure value Bp is calculated at 5T22, and the blood pressure value is determined. and,
Correction is performed using the function formula kBp stored in advance (Sr
23), further calculate the pulse rate (Sr24), and 5T2
Move to B. There are various algorithms for blood pressure calculation (blood pressure determination). Processing such as calculating the diastolic blood pressure from the high blood pressure and the average blood pressure is performed. When the measurement is completed, Sr2
Stop the pump motor 26 with B, and similarly
8 and moves to rapid exhaust (ST30), the light emitting element 15
is turned off (ST30) and the downward arrow is turned on (ST31). This downward arrow is a display indicating rapid exhaust. Then, it is determined whether the cuff pressure has become 5rmHg or less (5T32), and when it is 5mmHg or less, the downward arrow is turned off (ST33), and it is determined whether there is a measurement result or not (5T34), indicating that it is normal rather than an error. If there is a measurement result, the blood pressure value corrected at 5T23 is displayed on the display 4 (ST36), and the process returns to Sr1. If there is no measurement result, that is, there is an error, the process returns to Sr1. , to prepare for the next measurement.

Now, for example, the systolic blood pressure value Bp determined at 5T22 is 12
If it is 0 mmHg, the displayed blood pressure value is =
As 0.9, 0.9 X120 = 108 mmHg
becomes.

Although the above embodiment has been described using an electronic finger blood pressure monitor as an example, the present invention can also be applied to a so-called electronic blood pressure monitor for the arm, which measures blood pressure by attaching a cuff to the upper arm.

(F) Effects of the Invention According to this invention, a function indicating the relationship between the cuff pressure detected by the pressure sensor and the true compressive force on the artery is stored in advance, and the blood pressure value determined by the blood pressure determining means is is corrected using the function and the corrected blood pressure value is displayed on the display, so even people with high blood pressure will not be measured lower than the actual blood pressure, and accurate blood pressure measurements can be made.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the relationship between cuff pressure and compression force.
The figure is a perspective view of the external appearance of the digital finger blood pressure monitor according to the embodiment, and FIG.
Block diagram of an electronic finger blood pressure monitor according to an embodiment of the present invention, No. 4
FIG. 4(A), FIG. 4(B), and FIG. 4(C) are flowcharts for explaining the operation of the in-phase electronic blood pressure monitor. 2: Finger cuff. 12: MP'J, 15: Light emitting element. 16: Light receiving element (for pulse wave detection). 23: Semiconductor pressure sensor 26: Pump motor, 29: Slow exhaust valve Fig. 1 Fig. 2

Claims (1)

[Claims] (1) A cuff for compressing an artery, an air pressure supply means for supplying air pressure to the cuff, an air pressure adjustment means for changing the air pressure of the cuff, a pressure sensor for detecting the pressure of the cuff, and a pressure sensor for detecting the pressure of the cuff. Blood vessel information extraction means for extracting arterial blood vessel information in the process of changing air pressure, and blood pressure determining means for determining blood pressure based on the cuff pressure detected by the pressure sensor and the blood vessel information extracted by the blood vessel information extraction means. and,
An electronic sphygmomanometer including a display device for displaying the determined blood pressure value, further comprising: a function storage means for storing in advance a function indicating a correlation between the cuff pressure detected by the pressure sensor and the true compressive force on the artery;
An electronic blood pressure monitor comprising: blood pressure value correction means for correcting the blood pressure value determined by the blood pressure determination means using the function, and displaying the corrected blood pressure value on the display device.