JP2898779B2 - Automatic blood pressure measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic blood pressure measuring device for measuring blood pressure in the process of reducing a compression pressure, and more particularly to a technique for determining a target pressure increase value of the compression pressure.

[0002]

2. Description of the Related Art Conventionally, an automatic blood pressure measurement device of the type in which a living body is compressed by a compression device such as a cuff and a blood pressure value is measured based on a pulse wave or a Korotkoff sound sequentially obtained in the process of decreasing the compression pressure has been provided. The compression pressure of the compression device is usually increased to a relatively high target compression pressure (for example, a pressure of about 180 mmHg) before the pressure reduction.

[0003]

However, in the conventional automatic blood pressure measuring device, when the subject's systolic blood pressure value is higher than the predetermined target compression pressure, the measurement becomes impossible and the blood pressure measurement must be performed again. On the other hand, when the subject's systolic blood pressure value is significantly smaller than the predetermined target compression pressure, the burden imposed on the subject by the compression becomes unnecessarily large or the measurement time becomes unnecessarily long. There were drawbacks.

[0004] On the other hand, for example, a temporary systolic blood pressure value is determined in accordance with a normal oscillometric blood pressure value determining algorithm based on a pulse wave signal sequentially obtained in a process of increasing the compression pressure of the compression device. If the target compression pressure is determined so as to be higher by a predetermined amount than the provisional systolic blood pressure value, it is considered that the above-described disadvantages can be solved. Since the reliability is relatively low, it is difficult to appropriately determine the target compression pressure according to the systolic blood pressure value of the subject.

The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the compression pressure of a compression device to a target compression pressure and then reduce the blood pressure value in the process of decreasing the compression pressure. In the automatic blood pressure measurement device of the type that measures the target pressure, the target compression pressure can be suitably determined based on the systolic blood pressure value of the subject based on the pulse wave signal obtained in the pressure-increasing process. It is an object of the present invention to provide an automatic blood pressure measurement device that can preferably prevent measurement and can appropriately prevent a measurement subject from unnecessarily increasing burden and measurement time due to an excessive target compression pressure.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the gist of the present invention is to provide a compression device for compressing a living body, and a pressure signal indicating the compression pressure by detecting the compression pressure of the compression device. An automatic blood pressure measurement device comprising a pressure sensor that outputs a pressure signal, and after increasing the compression pressure of the compression device to a predetermined target compression pressure, measures a blood pressure value in the process of decreasing the compression pressure, (A) pulse wave discriminating means for discriminating a pulse wave signal that is a vibration component of the pressure signal,
(b) Provisionally determining a plurality of types of provisional blood pressure values including a systolic blood pressure value based on a change in the amplitude of a pulse wave represented by a pulse wave signal sequentially obtained by the pulse wave discriminating means in the process of increasing the compression pressure. Blood pressure value determining means, (c) fuzzy number determining means for determining the plurality of fuzzy numbers indicating the height of the blood pressure value based on the plurality of temporary blood pressure values, and (d) the plurality of kinds of temporary blood pressure values. Target compression pressure determining means for determining the target compression pressure by inference based on fuzzy numbers.

[0007]

In the automatic blood pressure measurement apparatus having the above-described structure, the pulse wave signal, which is the vibration component of the pressure signal sequentially output from the pressure sensor in the process of increasing the compression pressure of the compression device, is determined by the pulse wave discrimination means. The plurality of types of provisional blood pressure values including the systolic blood pressure value are determined by the provisional blood pressure value determination means based on a change in the amplitude of the pulse wave represented by the pulse wave signal. The fuzzy number determining means determines a plurality of fuzzy numbers indicating the height of the blood pressure value based on the plurality of temporary blood pressure values, and the fuzzy number determining means determines the plurality of fuzzy numbers. The target compression pressure is determined by the inference based on the number, and the pressure is increased to the determined target compression pressure. In this case, even if the reliability of each of the plurality of temporary blood pressure values including the systolic blood pressure value is relatively low, a plurality of fuzzy numbers corresponding to the plurality of temporary blood pressure values including the systolic blood pressure value are obtained. By determining the target compression pressure by inference based on the target compression pressure, the target compression pressure can be suitably determined according to the systolic blood pressure value of the subject. As a result, the target compression pressure can be appropriately determined according to the systolic blood pressure value of the subject based on the pulse wave signal obtained in the process of increasing the compression pressure of the compression device, and remeasurement due to lack of the target compression pressure can be performed. Provided is an automatic blood pressure measurement device that can preferably be prevented and can be preferably prevented from unnecessarily increasing a burden and a measurement time due to compression of a subject due to an excessive target compression pressure.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing an example of the configuration of an oscillometric automatic blood pressure measuring apparatus to which the present invention is applied.
In the figure, reference numeral 10 denotes a rubber bag-shaped cuff wound around the upper arm of the human body, etc., constituting a compression device of the present invention. The cuff 10 includes a pressure sensor 12, an air pump 1
4 and an exhaust valve 16 having a variable throttle are connected via a pipe 22. The pressure sensor 12 supplies a pressure signal SP representing the pressure in the cuff 10 to the static pressure discrimination circuit 24 and the pulse wave discrimination circuit 26, respectively. The static pressure discriminating circuit 24 includes a low-pass filter, and the pressure signal SP
And discriminates the cuff pressure signal SK representing the steady pressure included in the control device 29 through the A / D converter 28. The pulse wave discrimination circuit 26 includes a band pass filter, discriminates a pulse wave signal SM which is a vibration component of the pressure signal SP, and supplies the pulse wave signal SM to the control device 29 via the A / D converter 32. . This pulse wave signal S
The pulse wave represented by M is a pressure vibration wave generated from the brachial artery or the like and transmitted to the cuff 10 in synchronization with the heartbeat of the subject.
In this embodiment, the pulse wave discriminating circuit 26 constitutes a pulse wave discriminating means.

The control unit 29 includes a CPU 30, a ROM 3
4, a so-called microcomputer including a RAM 36, an output interface 40, and the like. C
The PU 30 outputs a drive signal from the output interface 40 by executing signal processing using the storage function of the RAM 36 according to a program stored in the ROM 34 in advance, and outputs the drive signal via the drive circuit (not shown).
4 and the exhaust valve 16 to control the cuff pressure P, and the provisional systolic blood pressure value based on the change in the amplitude of the pulse wave represented by the pulse wave signal SM sequentially obtained in the process of rapidly increasing the pressure in the cuff 10. , An average blood pressure value, and a diastolic blood pressure value, respectively, and based on each provisional blood pressure value, three types of fuzzy numbers indicating the height of the blood pressure value are determined for each provisional blood pressure value, and the three types are determined. The target cuff pressure Pm (target compression pressure) is determined based on the synthesis of the fuzzy number membership function, and the cuff pressure P is increased to the target cuff pressure Pm. The fuzzy number is a regular, convex, piecewise continuous fuzzy set having a set of real numbers as a base set. In the present embodiment, the control device 29 constitutes provisional blood pressure value determining means, fuzzy number determining means, and target compression pressure determining means.
In addition, the CPU 30 determines the systolic blood pressure value based on the change in the amplitude of the pulse wave represented by the pulse wave signal SM sequentially obtained in the process of gradually lowering the inside of the cuff 10 from the target cuff pressure Pm according to a program stored in the ROM 34 in advance. , The average blood pressure value, and the diastolic blood pressure value, and the determined blood pressure values are displayed on the display 38.

Next, the operation of the thus configured automatic blood pressure measuring apparatus will be described with reference to the flowchart shown in FIG.

When the power is turned on, an initial process (not shown) is executed, and then step S1 is executed to determine whether or not a start switch (not shown) has been turned ON. If this determination is denied, the standby state is set. If the determination is affirmed, step S2 is executed,
The exhaust valve 16 is closed, and the air pump 14 is driven to start rapid pressure increase at a predetermined pressure increase speed in the cuff 10. Next, step S3 is executed to execute the pulse wave signal SM.
Is read, and step S4 is executed to determine whether one pulse has been detected. Step S4
If the determination in step S3 is negative, steps S3 and S4 are repeatedly executed. If the determination is positive, the blood pressure value determination routine in step S5 is executed. In this blood pressure value determination routine, a provisional systolic blood pressure value, an average blood pressure value, and an average blood pressure value are determined in accordance with an oscillometric blood pressure value determination algorithm based on a change in the amplitude of the pulse wave sequentially detected in the pressure increasing process. You. That is, the amplitude is the cuff pressure P at which the maximum pulse wave was detected is determined as the mean blood pressure value MEAN ₁ provisional the mean blood pressure ME
The cuff pressure P at the inflection point of the pulse wave amplitude on the lower pressure side than AN ₁ is determined as the provisional diastolic blood pressure value DIA ₁ , and the inflection of the pulse wave amplitude on the higher pressure side than the mean blood pressure value MEAN _1. is the cuff pressure P is determined as the systolic blood pressure value SYS ₁ provisional at point. Next, by performing step S6, it is determined whether the blood pressure measurement has been completed.
If not yet completed, steps S3 to S6 are repeatedly executed.

When the blood pressure measurement is completed and the determination in step S6 is affirmed, step S7 is executed to determine whether or not the pressure in the cuff 10 is increasing. At the time when the provisional blood pressure value is measured, the blood pressure is being increased, so the determination in step S7 is affirmed, and step S8 is executed.
In step S8, the provisional systolic blood pressure value SYS ₁ and the average blood pressure value MEAN determined in step S5 are determined.
_1, and based on the diastolic blood pressure DIA _1, for example from a predetermined relationship as shown in FIG. 3, the fuzzy number indicating the height of the blood pressure value is three determined for each blood pressure values of the provisional.
In FIG. 3, the fuzzy number indicates the median value at which the grade of the membership function is the largest, and the median value 5
Fuzzy number is systolic blood pressure value SYS ₁ , mean blood pressure value MEA
N ₁ or the diastolic blood pressure value DIA ₁ is high, and the fuzzy number of the central value 4 is that those blood pressure values are slightly high.
A fuzzy number of median 3 indicates that their blood pressure values are normal, a fuzzy number of median 2 indicates that their blood pressure values are slightly lower, and a fuzzy number of median 1 indicates that their blood pressure values are lower. Each is represented. This allows, for example,
When the systolic blood pressure value SYS ₁ , the mean blood pressure value MEAN ₁ , and the diastolic blood pressure value DIA ₁ are 160, 140, and 89, respectively, the systolic blood pressure value SYS ₁ is a fuzzy number having a central value of 4, and the mean blood pressure value MEAN ₁ the center value is the fuzzy number of 5, diastolic blood pressure DIA ₁ becomes the center value is converted respectively to the fuzzy number of 3.

The above three types of fuzzy numbers have, for example, a membership function μA (x) shown in Equation 1. Number 1
Where α is the center value of the membership function and c
Is a value indicating the spread of the membership function from the center value α. Here, when the value of c is determined to be, for example, 2, the fuzzy number center value of the systolic blood pressure value SYS ₁ is 4, the fuzzy number center value of the mean blood pressure value MEAN ₁ is 5, and the diastolic blood pressure value DIA _{1 is as described above.} If the central value of the fuzzy number is 3, the systolic blood pressure value SYS ₁ and the average blood pressure value MEAN
₁ and each fuzzy number corresponding to the diastolic blood pressure value DIA ₁ is a membership function μA (x) shown in Equations 2 to 4.
_SYS , μA (x) _MEAN and μA (x) _DIA . Their membership function μA (x)
_SYS , μA (x) _MEAN and μA (x) _DIA are shown by broken _lines in FIG.

(Equation 1)

(Equation 2)

(Equation 3)

(Equation 4)

Next, by executing step S9, the membership functions of the three types of fuzzy numbers determined in step S8 are synthesized by the minimax operation, and the minimum value of the three types of membership functions is calculated. _Are calculated, and a composite membership function μA (x) _CONP is obtained. For example, when the membership function shown in Equation 2 to Equation 4, the synthetic membership function μA (x) _CONP shown by the solid line obtained in FIG. 4, this composite membership function μA (x) _CONP by number 5 expressed.

(Equation 5)

Next, step S10 is executed, and the composite membership function μA obtained in step S9 is obtained.
(X) The center value of the grade of the _CONP having the maximum grade is determined, and the step S11 is executed. Based on the center value of the composite membership function μA (x) _CONP , for example, as shown in FIG. The target cuff pressure Pm is determined from the predetermined relationship. When the composite membership function μA (x) _CONP is _represented by the above equation 5, the central value is 4, and the target cuff pressure Pm is determined to be 200 mmHg from the relationship shown in FIG.

When the target cuff pressure Pm is determined in this way, step S12 is executed to determine whether the cuff pressure P has reached the target cuff pressure Pm.
If the target cuff pressure Pm has not yet been reached, step S12
Is repeatedly executed, and the pressure increase in the cuff 10 is continued. However, if the target cuff pressure Pm has been reached, the determination in step S12 is affirmed and the step S13 is executed, whereby the air pump 14 is stopped. In addition, the exhaust valve 16 is set to the slow exhaust state at a predetermined speed, and the slow down of the pressure in the cuff 10 is started. Thereafter, the above steps S3 and subsequent steps are executed again. As a result, the blood pressure is measured in the slow blood pressure decreasing process in the same manner as in the blood pressure measurement in the pressure increasing process, and the systolic blood pressure value SYS ₂ , the average blood pressure value MEAN ₂ , and the diastolic blood pressure value DIA ₂ are determined. If it is determined in S6 that the blood pressure measurement has been completed, step S7 is executed to determine whether or not the cuff 10 is under pressure. At this time, since the gradual pressure decrease is being performed, the determination in step S7 is denied and step S14 is executed, whereby the systolic blood pressure value SYS ₂ , the average blood pressure value MEAN ₂ , and the diastolic blood pressure value DIA ₂ are displayed on the display 38. Is displayed, and the execution of step S15 causes the exhaust valve 1
After the cuff 10 is opened and the pressure in the cuff 10 is rapidly exhausted, the operation is terminated.

As described above, according to the present embodiment, the provisional systolic blood pressure value SYS ₁ , the average blood pressure value MEAN ₁ , and the diastolic blood pressure value are based on the pulse wave signal SM sequentially obtained during the rapid pressure increase process in the cuff 10. DIA ₁ is determined, and three fuzzy numbers indicating the height of the blood pressure value are determined based on the three temporary blood pressure values. Three triangular members representing the three fuzzy numbers are determined. The target cuff pressure Pm is determined from a predetermined relationship based on the center value having the maximum grade of the combined membership function obtained by combining the ship functions by the minimax operation. In this case, since the rate of increasing the cuff pressure P is high, the provisional systolic blood pressure value SYS ₁ , the average blood pressure value MEAN ₁ ,
And the individual reliability of the diastolic blood pressure value DIA ₁ is relatively low, but the inference based on the three kinds of fuzzy numbers corresponding to those tentative blood pressure values makes it possible to obtain the target cuff pressure P as described above.
By determining m, it can be suitably determined according to the target cuff pressure Pm in systolic blood pressure value SYS ₂ of the subject. As a result, the target cuff pressure Pm can be suitably determined according to the systolic blood pressure value of the subject based on the pulse wave signal SM obtained in the step of increasing the pressure in the cuff 10, and the target cuff pressure P
Automatic blood pressure measurement device that can appropriately prevent re-measurement due to shortage of m and can also prevent unnecessary increase in burden and measurement time due to compression of the subject due to excessive target cuff pressure Pm. Is provided.

In the above embodiment, the pulse wave discriminating means is constituted by the pulse wave discriminating circuit 26, but may be constituted by software in the ROM 34 of the control device 29.

Further, in the above embodiment, three types of provisional blood pressure values, a systolic blood pressure value, an average blood pressure value, and a diastolic blood pressure value, are determined, but they are not necessarily required. Even when two types of blood pressure values, or two types of systolic and diastolic blood pressure values are determined as temporary blood pressure values, it is possible to obtain a prima facie effect of applying the present invention. is there.

Further, in the above embodiment, a composite membership function consisting of a minimum of three types of fuzzy number membership functions is determined, and a center value of the composite membership function with the highest grade is determined. Although the target cuff pressure Pm is determined on the basis of this, it is not always necessary. For example, a composite membership function obtained by connecting the maximum values of the membership functions of the above three types of fuzzy numbers is obtained and the composite membership function is determined. May be configured to determine the target cuff pressure Pm based on obtaining the center of gravity of.

In the above embodiment, the predetermined relationship between the fuzzy number for determining the fuzzy number corresponding to the provisional blood pressure value and the blood pressure value is such that the magnitude of the blood pressure value is divided into five levels. Although it is configured stepwise, it may be configured continuously according to the magnitude of the blood pressure value.

Further, in the above embodiment, the predetermined relationship between the central value of the combined membership function and the target cuff pressure is defined by a two-dimensional graph having the central value and the target cuff pressure as the vertical and horizontal axes. It may be constituted by a function determined in coordinates.

In the above embodiment, the central value of the membership function of the fuzzy number is determined to be 5-1.
This is not always necessary. For example, the center value may be determined at 250, 200, 180, 160, and 140 representing the target cuff pressure. In this way, the target cuff pressure can be directly determined from the composite membership function.

In the above embodiment, the case where the present invention is applied to an oscillometric automatic blood pressure measuring apparatus has been described. However, it is needless to say that the present invention can also be applied to an automatic blood pressure measuring apparatus of the Korotkoff sound type. It is.

In addition, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of an automatic blood pressure measurement device to which the present invention has been applied.

FIG. 2 is a flowchart showing the operation of the apparatus of FIG.

FIG. 3 is a diagram showing an example of a predetermined relationship between a fuzzy number (center value) and provisional systolic, average, and diastolic values used in the flowchart of FIG. 2;

4 is a diagram showing an example of membership functions of three types of fuzzy numbers determined in the flowchart of FIG. 2 and their combined membership functions.

FIG. 5 is a diagram showing an example of a predetermined relationship between a center value of a combined membership function used in the flowchart of FIG. 2 and a target cuff pressure.

[Explanation of symbols]

Reference Signs List 10 cuff (compression device) 12 pressure sensor 26 pulse wave discrimination circuit (pulse wave discrimination means) 29 control device (temporary blood pressure value determination means, fuzzy number determination means, target compression pressure determination means)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) A61B 5/0225 A61B 5/022

Claims (1)

(57) [Claims] 1. A compression device for compressing a living body, and a pressure sensor for detecting a compression pressure of the compression device and outputting a pressure signal representing the compression pressure, wherein the compression pressure of the compression device is predetermined. After raising the pressure to the target compression pressure, an automatic blood pressure measurement device of the type that measures the blood pressure value in the process of reducing the compression pressure, pulse wave discrimination means for discriminating a pulse wave signal that is a vibration component of the pressure signal, Provisional blood pressure value determination for determining a plurality of types of provisional blood pressure values including a systolic blood pressure value based on a change in the amplitude of a pulse wave represented by a pulse wave signal sequentially obtained by the pulse wave discriminating means in the process of increasing the compression pressure Means, fuzzy number determining means for determining the plurality of fuzzy numbers indicating the height of the blood pressure value based on the plurality of temporary blood pressure values, and the target compression by inference based on the plurality of fuzzy numbers. Eye to determine pressure An automatic blood pressure measurement device comprising: a target compression pressure determining means.