JPH0546413Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a blood pressure monitoring device, and more particularly, to a blood pressure monitoring device that monitors blood pressure values based on pressure pulse waves detected from arteries in peripheral parts of a living body.

Prior Art A pulse wave sensor is equipped with a pressure surface on which a large number of pressure sensitive elements are arranged and is pressed onto an artery in a peripheral part of a living body, and detects a pressure pulse wave generated from the artery. A blood pressure monitoring device that selects an optimal pressure sensing element based on the pressure pulse wave signal output from each pressure element, and sequentially determines a blood pressure value based on the pressure pulse wave signal output from the optimal pressure sensing element. is being considered.

Problems that the invention aims to solve By the way, in such a blood pressure monitoring device, if the pulse wave sensor shifts due to body movement of the living body, the optimal pressure sensing element that has been selected may no longer be located at the optimal position. As a result, the reliability of the monitored blood pressure value may be impaired. On the other hand, it is sequentially determined whether or not the optimal pressure-sensitive element is actually located at the optimal position, and if the determination is denied, the optimal pressure-sensitive element is changed to the pressure-sensitive element that is actually located at the optimal position. By switching, it is thought that even if the pulse wave sensor is deviated, the reliability of the monitored blood pressure value can be maintained.

However, in this case, if the optimal pressure-sensitive element is immediately switched after just one judgment that it is not located at the optimal position, even if the pulse wave sensor is only momentarily shifted, the optimal pressure-sensitive element will not be located at the optimal position. Pressure elements may be switched one by one, making it difficult to stably monitor blood pressure values.

The present invention was developed against the background of the above-mentioned circumstances, and its purpose is to suitably maintain the reliability of the blood pressure value being monitored even if the pulse wave sensor shifts, and to maintain a stable blood pressure value. An object of the present invention is to provide a blood pressure monitoring device that can monitor blood pressure.

Means for Solving the Problems In order to achieve the above object, the present invention provides a blood pressure monitoring device of the type described above, and as shown in the claim correspondence diagram of FIG. (b) optimal pressure-sensitive element determining means for repeatedly determining a pressure-sensitive element estimated to be located at an optimal position in response to pressure pulse waves being detected by the pressure-sensitive element; and (b) the optimal pressure-sensitive element. Sequentially determining whether or not the pressure sensing element estimated to be located at the optimal position determined by the determining means matches the optimal pressure sensing element already selected for determining the blood pressure value. and (c) a pressure-sensitive element that is estimated to be located at the optimum position when the judgment by the coincidence judgment means is negative a predetermined number of times in succession, as the optimum pressure-sensitive element. and a pressure sensitive element selection means for selecting the pressure sensitive element.

In the blood pressure monitoring device configured as described above, the optimal pressure sensing element determining means estimates that the pressure pulse wave is located at the optimal position according to the detection of pressure pulse waves by a large number of pressure sensing elements. The pressure sensing element is repeatedly determined, and whether or not the pressure sensing element estimated to be located at its optimal position matches the optimal pressure sensing element already selected for determining the blood pressure value. are sequentially judged by the coincidence judgment means,
When the judgment by the coincidence judgment means is negative a predetermined number of times in succession, the pressure-sensitive element selection means selects the pressure-sensitive element estimated to be located at the optimum position as the optimum pressure-sensitive element. Ru.

Effects of the invention As described above, according to the blood pressure monitoring device of the present invention,
Even if the pulse wave sensor shifts due to body movement, etc., the pressure sensing element is estimated to be located at the optimal position and the optimal pressure sensing element has already been selected to determine the blood pressure value. If it is determined that the pressure sensing element does not match, the pressure sensing element that is estimated to be located at the optimal position is selected as the new optimal pressure sensing element, and the blood pressure value is determined based on the new optimal pressure sensing element. is monitored, the reliability of the monitored blood pressure value can be suitably maintained. Moreover, it is determined that the pressure-sensitive element estimated to be located at the optimal position does not match the optimal pressure-sensitive element already selected for determining the blood pressure value for a predetermined number of consecutive times. When the pulse wave sensor shifts momentarily, the pressure-sensitive element that is estimated to be at the optimal position is selected as the new optimal pressure-sensitive element. can be prevented from being switched all at once, and blood pressure values can be stably monitored.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 3 is a diagram showing the configuration of the blood pressure monitoring device of this embodiment. In the figure, 10 is a rubber bag-shaped cuff that is wrapped around, for example, an upper arm 12 of a human body and presses it. A pressure sensor 14, a switching valve 16, and an electric pump 18 are connected to the cuff 10 via piping 20, respectively. The pressure sensor 14 detects the pressure inside the cuff 10 (cuff pressure P) and sends a cuff pressure signal SP representing the cuff pressure P to A/
It is output to the CPU 24 via the D converter 22. The switching valve 16 can be switched to three states: a pressure supply state, a slow exhaust state, and a rapid exhaust state. When the switching valve 16 is in the pressure supply state, pressure is supplied from the electric pump 18 to the cuff 10, and when the cuff pressure P reaches a predetermined target cuff pressure, the switching valve 16 is switched to the slow evacuation state and the cuff 10 is The inside of the cuff 10 is slowly evacuated at a predetermined speed, and after the blood pressure is measured during the slow blood pressure reduction process of the cuff 10, the switching valve 16 is switched to the rapid exhaust state and the inside of the cuff 10 is quickly evacuated. It's becoming like that.

The CPU 24 connects to the ROM via the data bus line.
26, RAM 28, and I/O port 27, and performs signal processing using the storage function of RAM 28 according to a program stored in advance in ROM 26, and drives electric pump 1 by drive circuit 30.
8 and the switching state of the switching valve 16, the cuff pressure P is adjusted as described above, and the magnitude of the fluctuation component of the cuff pressure P detected during the slow pressure reduction process within the cuff 10 is adjusted. The systolic blood pressure value is determined based on the change in . Note that the algorithm for determining the systolic blood pressure value is well known and is not necessarily necessary for understanding the present invention, so a detailed explanation thereof will be omitted.

In addition, the CPU 24 has a pulse wave sensor 32 connected to the A/
It is connected via a D converter 34. The pulse wave sensor 32 includes a large number of pressure-sensitive diodes 42 on a pressing surface 40 of a semiconductor chip, as shown in FIG. 4, for example.
are arranged in a line at predetermined intervals, and are attached to the inner surface of the band 36, which is provided with a pair of fasteners (not shown) at both ends. The pulse wave sensor 32 is arranged, for example, on the radial artery (not shown) of the wrist 37 with the arrangement direction of the pressure-sensitive diodes 42 being substantially perpendicular to the radial artery, and the band 36 is wound around the wrist 37 to bring the fasteners into close contact with each other. 10 to 10 for the radial artery
It is designed to be pressed with a constant pressure of about 100mmHg. In this embodiment, the wrist 37 corresponds to the peripheral part of the living body, the radial artery corresponds to the artery, and the pressure-sensitive diode 42 constitutes the pressure-sensitive element. Each pressure-sensitive diode 42 detects a pressure pulse wave due to pulsation of the radial artery, and sends a pressure pulse wave signal SM representing the pressure pulse wave to the CPU 24 via the A/D converter 34.
supply to.

The CPU 24 determines the relationship between the systolic blood pressure value measured by the cuff 10 and the highest value (mV) of the pressure pulse wave signal SM representing the pressure pulse wave detected by the pulse wave sensor 32, and from this relationship, the pulse wave sensor 32
While sequentially determining the systolic blood pressure value and the diastolic blood pressure value based on the pressure pulse waves sequentially detected by and continuously displaying these blood pressure values on the blood pressure display 29,
If necessary, the above relationship is updated and the optimum pressure sensitive diode 42A, which will be described later, is switched.

The operation of this embodiment will be explained below with reference to the flowchart shown in FIG.

First, when a power switch (not shown) is turned on, initial processing is executed, and it is determined whether or not a start switch (not shown) is turned on. If this judgment is affirmative, step S1 is executed. Systolic blood pressure value SYS is measured using cuff 10. Next, by executing step S2, pressure pulse wave signals SM representing pressure pulse waves are read from each pressure sensitive diode 42, and the amplitudes of each pressure pulse waves are calculated and the maximum amplitude is determined. Then, the pressure sensitive diode 42 that has detected the pressure pulse wave having the maximum amplitude is selected as the optimum pressure sensitive diode 42A. This optimum pressure-sensitive diode 42A corresponds to the optimum pressure-sensitive element of this embodiment.

Here, blood pressure value P _B and pressure pulse wave size M (mV)
For example, it has been experimentally determined that the following equation (1) holds true between . That is, the systolic blood pressure value SYS measured in step S1 and the maximum value M _nax of the pressure pulse wave detected by the optimal pressure-sensitive diode 42A selected in step S2 are respectively substituted into equation (1). Therefore, the intercept b in equation (1) is
(2).

P _B = a × M + b ... (1) b = SYS - a × M _nax ... (2) However, a: a value unique to each pressure-sensitive diode Next, when step S4 is executed, the optimum position is reached. Pressure sensitive diode 42 estimated to be located
B is determined. That is, as in step S2, the pressure pulse wave signal is output from each pressure sensitive diode 42.
As each SM is read, the amplitude of the pressure pulse wave represented by the pressure pulse wave signal SM is calculated, the maximum amplitude is determined, and the pressure sensitive diode 42 that detected the pressure pulse wave having the maximum amplitude is placed at the optimal position. It is determined that the pressure sensitive diode 42B is located at . Next steps
In S5, it is determined whether or not the optimum pressure sensitive diode 42A selected in step S2 matches the pressure sensitive diode 42B determined in step S4. In this embodiment, the pressure-sensitive diode 42B corresponds to the pressure-sensitive element that is estimated to be located at the optimal position, and
S4 corresponds to the optimal pressure-sensitive element determining means, and step S5 corresponds to the matching determining means, respectively. step
If the determination in S5 is negative, step S6 is executed to turn on a blood pressure monitor start switch (not shown) to determine whether or not blood pressure is being monitored. After step S7 is executed and the pressure sensitive diode 42B is newly selected as the optimum pressure sensitive diode 42A, steps S4 and subsequent steps are executed again.

If it is determined in step S6 that the blood pressure is being monitored, the following step S8 is executed, 1 is added to the contents of counter C that counts the number of times the determination in step S5 is negative, and step S9 is executed. Then, it is determined whether the count of the counter C has reached 3 or not. If it is determined that the count content of the counter C has not yet reached 3, step S12 is executed to determine the maximum pressure pulse wave detected by the optimal pressure-sensitive diode 42A selected in step S2. value
By determining M _nax and the lowest value M _nio , and executing step S13,
The relationship determined in step S3, that is, the above (1)
From the formula, the systolic blood pressure value H and the diastolic blood pressure value L are determined based on the maximum value M _nax and the minimum value M _nio , respectively. Next, after step S14 is executed and the blood pressure values are displayed on the blood pressure display 29, steps S4 and subsequent steps are executed again.

On the other hand, if it is determined in step S5 that the pressure sensitive diode 42B and the optimum pressure sensitive diode 42A match, step S15 is executed and it is determined whether or not blood pressure monitoring is in progress as in step S6. If the blood pressure is not being monitored, the process returns to step S4, but if it is determined that the blood pressure is being monitored, the counting contents of the counter C are cleared in the subsequent step S16, and then steps S12 to S14 are executed. The systolic blood pressure value H and the diastolic blood pressure value L are determined and displayed, and steps S4 and subsequent steps are executed again.

While the series of steps starting from step S4 are repeatedly executed, if it is determined in step S9 that the count content of counter C has reached 3, step S10 is executed, so that, for example, as shown in FIG. As shown, the highest value of the three-beat pressure pulse wave (C in Fig. 5) detected by the pressure-sensitive diode 42B after it was determined that 42A≠42B.
The moving average of M _nax and the highest value M _nax of the three-beat pressure pulse wave (D in Fig. 5) detected by the optimal pressure-sensitive diode 42A immediately before it is determined that 42A≠42B.
The relationship determined in step S3 is updated based on the moving average of the systolic blood pressure value H determined based on the respective values. Next, by executing step S11, the pressure sensitive diode 42B
is newly selected as the optimum pressure sensitive diode 42A. In this embodiment, steps S8, S9,
S11 corresponds to the pressure sensitive element selection means. In the following step S12, the highest value M _nax and the lowest value M _nio of the pressure pulse wave detected by the new highest pressure sensitive diode 42A selected in step S11 are determined, and in step S13,
The systolic blood pressure value H and the diastolic blood pressure value L are respectively determined from the relationship updated in step S10 based on the maximum value M _nax and the minimum value M _nio . After those blood pressure values are displayed on the blood pressure display 27 in step S14, steps S4 and subsequent steps are executed again.

While the series of steps starting with step S4 are repeatedly executed as described above, if the judgment in step S9 is affirmed again, the previously updated relationship is updated again in the same way as in the case described above. At the same time, the optimal pressure sensitive diode 42A is switched again and blood pressure monitoring continues.

As described above, according to this embodiment, even if the pulse wave sensor 32 is displaced due to body movement of the subject, it is estimated that the pulse wave sensor 32 is located at the optimal position in the displaced state. The pressure sensitive diode 42B that has been selected is newly selected as the optimal pressure sensitive diode 42A, and the blood pressure value is monitored based on the newly selected optimal pressure sensitive diode 42A, so the reliability of the monitored blood pressure value is favorable. will be maintained.

Furthermore, according to this embodiment, when it is determined that the pressure-sensitive diode 42B that is estimated to be located at the optimal position and the optimal pressure-sensitive diode 42A do not match, the determination that they do not match is made three times. When performed continuously, the pressure sensitive diode 42
Since B is selected as the optimum pressure-sensitive diode 42A, it is preferably prevented that the optimum pressure-sensitive diodes 42A are switched one by one in the event that the pulse wave sensor 32 momentarily deviates. This allows for stable monitoring.

Furthermore, according to the present embodiment, when the count content of the counter C becomes 3 or more in step S9, steps S10 and subsequent steps are executed. The relationship is updated and the optimal pressure sensitive diode 42A
Step S5 continues despite being switched
If the decision is again denied, the step
There is an advantage in that the decision in step S9 is immediately affirmed without waiting until the decision in step S5 is denied three times, and the relationship and the optimum pressure sensitive diode 42A can be suitably corrected.

In the above embodiment, the pressure sensitive diode 42 in which the pressure pulse wave with the maximum amplitude was detected is selected as the optimum pressure sensitive diode 42A, and the pressure sensitive diode 42 is selected as the optimum pressure sensitive diode 42A.
Although it is configured to be judged as 2B,
For example, a plurality of pressure-sensitive diodes 4 located directly above an artery among a large number of pressure-sensitive diodes 42
2 is detected, and the one located in the center of those pressure sensitive diodes 42 is selected as the optimal pressure sensitive diode 4.
It is also possible to configure it so that it is selected as 2A and determined as pressure sensitive diode 42B.

Further, in the above-described embodiment, the relationship is updated and the optimal pressure-sensitive diode 42A is switched when the judgment in step S5 is negative three times. Of course, this is a good thing.

Furthermore, in the above-mentioned embodiment, the moving average of the highest value of the three-beat pressure pulse wave detected by the pressure-sensitive diode 42B after it is determined that 42A≠42B,
The above relationship is updated based on the moving average of the systolic blood pressure values determined by the highest values of the pressure pulse waves of three beats detected by the optimal pressure-sensitive diode 42A immediately before it is determined that ≠42B. , it doesn't necessarily have to be configured that way, for example,
The highest value of the pressure pulse wave at the third beat detected by the pressure-sensitive diode 42B after it was determined that 42A≠42B, and the pressure for one beat detected by the optimal pressure-sensitive diode 42A immediately before it was determined that 42A≠42B. The relationship may be updated based on the systolic blood pressure value determined based on the maximum value of the pulse wave.

Further, in the above-mentioned embodiment, the relationship between the systolic blood pressure value P _B measured by the cuff 10 and the maximum value M of the pressure pulse wave detected by the pulse wave sensor 32 is proportional as shown in equation (1) above. However, the relationship may be non-linear.

Furthermore, in the above-mentioned embodiment, the slope a of the above equation (1) is a unique value for each pressure-sensitive diode 42 and is determined in advance, and is based on the systolic blood pressure value measured by the cuff 10 and the pulse wave sensor 32. The above relationship is determined by determining the intercept b of equation (1) based on the highest value of the detected pressure pulse wave. The above a and b may be determined together by substituting the systolic blood pressure value and the highest value of the pressure pulse wave, and the diastolic blood pressure value and the lowest value of the pressure pulse wave into equation (1), respectively.

Further, in the above embodiment, the relationship between the blood pressure value measured by the cuff 10 and the pressure pulse wave detected by the pulse wave sensor 32 is determined, and the blood pressure is determined based on the pressure pulse wave actually detected from this relationship. Although the configuration is such that the values are determined sequentially, it is also possible to configure the blood pressure value to be determined directly from the magnitude of the pressure pulse wave without determining such a relationship.

Further, in the above embodiment, the pressure sensitive diode 42
are arranged in a line, but with the aim of arranging more in the direction intersecting the artery,
They may be arranged in multiple rows so as not to overlap each other in the direction perpendicular to the arrangement direction.

Further, in the above-described embodiment, the pressure-sensitive element is composed of the pressure-sensitive diode 42, but it may also be composed of a semiconductor element such as a pressure-sensitive transistor or a pressure-sensitive resistor, or a semiconductor element. It is also possible to use other pressure sensitive elements.

Furthermore, in the above embodiments, the radial artery is used as the artery in the peripheral part of the living body, but the dorsalis pedis artery or the like may also be used.

In addition, various changes may be made to the present invention without departing from the gist thereof.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the claims of the present invention. Second
The figure is a flowchart for explaining the operation of the apparatus shown in FIG. FIG. 3 is a diagram illustrating the configuration of a blood pressure monitoring device that is an embodiment of the present invention. FIG. 4 is a diagram showing a pressure sensitive diode formed on the pressing surface of the pulse wave sensor. FIG. 5 is a diagram for explaining the flowchart of FIG. 2. 32... Pulse wave sensor, 37... Wrist (distal part of living body), 40... Pressing surface, 42... Pressure sensitive diode (pressure sensitive element).

Claims (1)

[Claims for Utility Model Registration] A pulse wave sensor having a pressing surface on which a large number of pressure sensing elements are arranged is pressed onto an artery in a peripheral part of a living body and detects a pressure pulse wave generated from the artery. , selects an optimal pressure sensing element based on pressure pulse wave signals output from each of the plurality of pressure sensing elements, and sequentially determines a blood pressure value based on the pressure pulse wave signals output from the optimal pressure sensing element. An optimal pressure-sensitive element that repeatedly determines a pressure-sensitive element that is estimated to be located at an optimal position in response to pressure pulse waves being detected by the plurality of pressure-sensitive elements. determining means; a pressure-sensitive element estimated to be located at the optimal position determined by the optimal pressure-sensitive element determining means; and the optimal pressure-sensitive element already selected for determining the blood pressure value. a coincidence determining means for sequentially determining whether or not they match; and a pressure-sensitive element that is estimated to be located at the optimal position when the determination by the coincidence determining means is negative a predetermined number of times in succession. A blood pressure monitoring device characterized by comprising: pressure sensitive element selection means for selecting the optimum pressure sensitive element.