WO2014162360A1

WO2014162360A1 - Sphygmomanometer and blood pressure value computation method

Info

Publication number: WO2014162360A1
Application number: PCT/JP2013/002374
Authority: WO
Inventors: 孝博相馬
Original assignee: テルモ株式会社
Priority date: 2013-04-05
Filing date: 2013-04-05
Publication date: 2014-10-09

Abstract

An objective of the present invention is to effect an improvement in measurement precision in a sphygmomanometer. The present invention is a sphygmomanometer, which is connected to a triple cuff, and which detects a cuff pressure in a depressurization procedure wherein a plurality of pulse wave components is superpositioned in time series, said sphygmomanometer comprising: a computation means for specifying, for each of the plurality of pulse wave components which are superpositioned in the detected cuff pressure, an amplitude peak point and a bottom point which appears in advance of the peak point, sequentially extracting a prescribed number of instances of contiguous pulse wave data between the bottom point and the peak point, computing an incline of a regression line for each instance of the extracted pulse wave data, deriving a fluctuation of the incline between the bottom point and the peak point, and computing a characteristic quantity based on a time difference between a time at which a derivative of the fluctuation is zero and the bottom point; and a determination means for determining that the cuff pressure corresponding to the pulse wave component whereat the change between pulse wave components with respect to the characteristic quantity which is computed for each of the plurality of pulse wave components reaches a maximum is a systolic blood pressure value.

Description

Blood pressure measurement device and blood pressure value calculation method

The present invention relates to a blood pressure measurement device and a blood pressure value calculation method.

In the treatment of hypertension, it is important to perform blood pressure measurement with high accuracy. For example, in an oscillometric blood pressure measurement device, conventionally, various blood pressure values based on pulse waves have been calculated with high accuracy. Proposals have been made.

Specifically, for example, in Patent Document 1 described below, a pulse wave detection air bag for selectively detecting the cuff at the peripheral side of the cuff at the central portion of the cuff where the pressure of the air bag for ischemia is most reflected. A so-called double cuff method has been proposed that improves the ability to detect a pulse wave squeezed out to the cuff peripheral side.

Furthermore, a so-called triple cuff method has also been proposed so that even when the pulse wave is small, a pulse wave struck to the cuff distal side can be detected.

In the triple cuff method, first, the maximum gradient point between the peak point of the detected pulse wave and the bottom point appearing preceding the peak point is detected, and the detected maximum gradient point and the maximum gradient point are preceded. The phase difference is extracted by dividing the time difference from the bottom point appearing by one period of the pulse wave. Then, in each pulse wave, a systolic blood pressure value (maximum blood pressure value) and / or a diastolic blood pressure value (minimum blood pressure value) is calculated by using the extracted time difference or phase difference as a feature amount (for example, the following patents) Reference 2).

JP 2005-185295 A JP 2009-101085 A

However, in the case of an oscillometric blood pressure measurement device that uses a pulse wave when calculating a systolic blood pressure value and / or a diastolic blood pressure value, pressurization interposed as a transmission medium until the pulse wave is transmitted to the pressure sensor. When the amount of air (the amount of air in the pulse wave detection system) increases, there is a problem that the measurement accuracy decreases.

This will be explained with specific examples. The amount of air in the pulse wave detection system increases, for example, to increase the amount of air in the pipe by increasing the length of the pipe that feeds air to the cuff body in order to improve user convenience. Can be mentioned. Alternatively, when the cuff used for the subject's thigh or used for the subject having an extremely thick arm is used, the amount of air in the ischemic bladder increases. Furthermore, even when the cuff is loosely attached to the subject, the amount of air in the air bag for ischemia increases.

As described above, when the amount of air in the pulse wave detection system increases for various reasons, a sudden change in the pulse wave generated on the cuff distal side when the cuff pressure becomes lower than the systolic blood pressure is attenuated. Even in a triple cuff that can attenuate a simple pulse wave, it may be difficult to detect the maximum gradient point. As a result, feature quantities such as time difference or phase difference cannot be extracted correctly, and the influence on the measurement accuracy of systolic blood pressure values and diastolic blood pressure values becomes inevitable.

Therefore, in order to improve the measurement accuracy in the blood pressure measurement device that calculates the systolic blood pressure value and / or the diastolic blood pressure value using the feature amount extracted from each pulse wave, the pulse wave detection system It is desirable to use a feature amount that can be extracted regardless of the increase or decrease of the air amount.

The present invention has been made in view of the above problems, and an object thereof is to improve measurement accuracy in a blood pressure measurement device.

In order to achieve the above object, a blood pressure measurement device according to the present invention has the following configuration. That is,
An air bag for ischemia that is laid on the side in contact with the blood pressure measurement site and compresses the entire blood pressure measurement site;
A sub-air bag that is laid on the side of the blood bag for measuring blood pressure that is in contact with the blood pressure measurement site and compresses the heart side of the blood vessel of the blood pressure measurement site;
A pulse wave detection air bag that is laid on the side of the blood bag for blood pressure measurement that is in contact with the blood pressure measurement site and detects a pulse wave at the center of the blood vessel of the blood pressure measurement site;
A blood pressure measurement device that detects a cuff pressure in a decompression process, in which a plurality of pulse wave components are superimposed in time series,
For each of the plurality of pulse wave components superimposed on the detected cuff pressure,
Identify the amplitude peak point and the bottom point that appears before the peak point,
Between the bottom point and the peak point, it sequentially extracts a predetermined number of pulse wave data, calculates the slope of the regression line for each extracted pulse wave data,
Obtain the variation of the slope between the bottom point and the peak point,
A calculating means for calculating a feature amount based on a time difference between the time point when the differential value of the fluctuation becomes zero and the bottom point;
Determining means for determining, as a systolic blood pressure value, the cuff pressure corresponding to the pulse wave component having the maximum change between the pulse wave components of the feature amount calculated for each of the plurality of pulse wave components; .

According to the present invention, it is possible to improve the measurement accuracy in the blood pressure measurement device.

Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are denoted by the same reference numerals.

The accompanying drawings are included in the specification, constitute a part thereof, show an embodiment of the present invention, and are used to explain the principle of the present invention together with the description.
FIG. 1 is a diagram showing a configuration of a blood pressure measurement device 100 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a state in which a pulse wave component is superimposed on the cuff pressure in time series in the process of reducing the cuff pressure. FIG. 3 is a longitudinal sectional view of the cuff body 101 of the blood pressure measurement device 100. FIG. 4 is a diagram schematically showing each component included in the pulse wave component PW. FIG. 5 is a diagram schematically showing how the W1-A component derived from the change in the intravascular volume under the cuff central portion A is generated and changed in the process of reducing the cuff pressure. FIG. 6A is a diagram showing a pulse wave component detected when the cuff pressure is between the systolic blood pressure value and the diastolic blood pressure value. FIG. 6B is a diagram showing a fluctuation (slope fluctuation curve) of the slope of the regression line from the bottom point to the peak point, calculated for each pulse wave component. FIG. 7A is a flowchart showing the flow of blood pressure value calculation processing. FIG. 7B is a flowchart showing the flow of blood pressure value calculation processing. FIG. 8 is a flowchart showing the flow of the slope fluctuation curve calculation process. FIG. 9 is a flowchart showing the flow of the feature amount extraction process. FIG. 10 is a diagram illustrating the relationship between the phase difference and the cuff pressure. FIG. 11 is a flowchart showing the flow of diastolic blood pressure value determination processing and systolic blood pressure value determination processing. FIG. 12 is a flowchart showing the flow of blood pressure measurement processing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

<1. Configuration of blood pressure measurement device>
FIG. 1 is a diagram showing a configuration of a blood pressure measurement device 100 according to an embodiment of the present invention. As shown in FIG. 1, the cuff body 101 includes a cloth cuff member 102 that is detachably provided to a blood pressure measurement site including the upper arm.

A male (hook type) hook-and-loop fastener 103 is disposed at the end of the cuff member 102 on the blood pressure measurement site contact side. A female (loop-type) surface fastener 104 is disposed on the surface opposite to the blood pressure measurement site contact side. The cuff body 102 is detachably attached to the upper arm portion of the subject by winding the cuff member 102 around the upper arm portion of the subject as shown in the figure and engaging the hook-and-

loop fasteners

103 and 104. The hook-and-loop fastener is merely an example, and other members may be used (for example, the cuff body may be formed in a cylindrical shape and the upper arm portion may be inserted into the cylinder).

In the cuff member 102, an air bag 108 for ischemia is laid to press the entire blood pressure measurement site. On the blood pressure measurement site contact side of the ischemic air bladder 108, a sub air bag 107 formed with a width narrower than that of the ischemic air bladder 108 is laid in order to compress the heart side of the blood pressure measurement site. A first buffer member 109 that attenuates vibration of the sub air bag 107 is provided between the sub air bag 107 and the ischemic air bag 108.

Further, on the blood pressure measurement site contact side of the ischemic air bladder 108, a pulse wave detection air bag 105 is laid that compresses the blood vessel downstream side of the blood pressure measurement site and detects a downstream pulse wave.

In addition, in order to pressurize the cuff body 101, the air bag 108 for ischemia of the cuff body 101 is connected to a pump 123 which is a pressure increasing / decreasing means via a second pipe 112, a pipe 115, and a cross-branching portion 120. Similarly, the pulse wave detection air bag 105 of the cuff body 101 is connected to the first piping 111, the fluid resistor 114 and the piping 115, and the cross-branching portion 120, and the sub air bag 107 is connected to the third piping 113, The on-off valve 116, the pipe 113a, and the cross branch part 120 are connected to the pump 123, respectively.

Furthermore, the air bag 108 for ischemia is connected to a pressure sensor 131 capable of detecting a cuff pressure signal from a pressure change via a second pipe 112 and a fluid resistor 114. The pulse wave detection air bladder 105 is connected to the pressure sensor 131 via the first pipe 111.

The first piping 111, the second piping 112, and the third piping 113 are made of soft tubes, and are configured to be detachable from the main body 130 via the connector 110.

Further, in order to reduce the pressure of the cuff body 101, a quick exhaust valve / constant speed exhaust valve 122 is further connected to the cross-branching portion 120, and the quick exhaust valve / constant speed exhaust valve 122 is connected to the control unit 148. Has been. In addition, an on-off valve 116 is connected to the pipe 113 a, and the on-off valve 116 is connected to the control unit 146.

The control unit 148 controls the opening area of the solenoid valve of the quick exhaust valve / constant speed exhaust valve 122 according to a command from the central control unit 135, and the control unit 146 opens / closes the electromagnetic on / off valve of the on / off valve 116. To control.

The pump 123 is driven based on power supply from a pump driving unit 149 connected to the motor M, and pressurizes the outside air introduced into the pump through the opening 123a. Pressurized air obtained by pressurizing the outside air is sent to the first pipe 111 to the third pipe 113, whereby each air bag is pressurized.

The rapid exhaust valve / constant speed exhaust valve 122 has a structure in which the opening area is varied according to the strength of the electromagnetic force in order to achieve a pressure reduction speed of 2 to 4 mmHg per second. A predetermined decompression speed is realized by being controlled based on the drive signal.

In the pressure sensor 131, the ischemic pressure signal from the ischemic air bag 108 in which the pulse wave component is attenuated and the pulse wave pressure from the pulse wave detecting air bag 105 including the pulse wave component are passed through the fluid resistor 114. A cuff pressure signal including the signal is detected.

The pressure sensor 131 is connected to a pressure measuring unit 132 that converts an analog electric signal, and the pressure measuring unit 132 is connected to an A / D converter 133. As a result, the cuff pressure signal is input to the central control unit 135 as a digital signal.

The central control unit 135 includes a RAM 138 that reads and writes cuff pressure signals and analysis results, a pulse wave processing unit 139 that detects a pulse wave component superimposed on the cuff pressure signal in time series, and a cuff (ischemic blood pressure). And a cuff pressure control unit 140 that pressurizes and decompresses the air bag, the pulse wave detection air bag, and the sub air bag. In addition, a blood pressure calculation unit 141 that calculates a blood pressure value from the detected pulse wave component and the ischemic pressure signal, a display control unit 137a that displays the calculated blood pressure value on a liquid crystal display unit 137 that is a blood pressure display unit, and a central control unit A ROM 136 that stores various control programs that can be read by the computer 135 is disposed. The RAM 138 also functions as a work area when various control programs are executed by the central control unit 135.

Further, the central control unit 135 includes a liquid crystal display unit 137 that displays a blood pressure value, and each drive that performs the above-described drive control (pump 123, rapid exhaust valve / constant exhaust valve 122, and open / close valve 116 drive control). Are connected.

Further, a power supply unit 143 including a dry battery is connected, and power from the power supply unit 143 is supplied to each unit via the central control unit 135 by operating the measurement start switch 142.

In the blood pressure measurement device 100 configured as described above, the central control unit 135 reads out various control programs stored in the ROM 136, and executes various processes by executing processing and determination of the entire blood pressure measurement device 100. is doing.

<2. Explanation of pulse wave component>
Next, the pulse wave component superimposed on the cuff pressure signal in time series will be described with reference to FIG. FIG. 2 is a graph showing how the pulse wave component is superimposed on the cuff pressure signal in time series during the cuff pressure depressurization process. The horizontal axis represents the elapsed time from the start of depressurization, and the vertical axis represents the respective time. It shows the cuff pressure over time. As shown in FIG. 2, the magnitude and shape of the pulse wave component change as the cuff pressure decreases.

<3. Configuration of triple cuff>
Next, the configuration of the triple cuff that is closely related to the magnitude and shape of the pulse wave component superimposed in time series on the cuff pressure signal will be briefly described. FIG. 3 is a cross-sectional view of the cuff body 101 (triple cuff) of the blood pressure measurement device 100 in the longitudinal direction (the direction in which the upper arm extends).

As shown in FIG. 3, the pressurized air bag 108 and the sub air bag 107 block the blood vessel 300 at the portion Q and suppress the blood flow from the upstream side 300a to the downstream side 300b.

The force for compressing the upper arm portion by the air bag 108 for ischemia is strongest at the center portion in the width direction of the cuff body 101 (the portion A in FIG. 3, hereinafter simply referred to as the cuff center portion A), and as it approaches the both ends. It becomes weaker and becomes almost zero at both ends. However, unlike the case of the double cuff that does not include the sub air bag 107, in the case of the triple cuff, the invasion of blood flow is prevented even in the section indicated by “B” in FIG.

The pulse wave detection air bag 105 is provided in the cuff central portion A, and best captures the intravascular pressure change (intravascular volume change) in the cuff central portion A. In the present specification, “cuff pressure” means the pressure in the air bag 108 for ischemia, but substantially the upper arm portion at the cuff central portion A in the width direction of the cuff body 101. Equal to the pressure of That is, it is also the pressure from the cuff body 101 applied to the blood vessel below the cuff central portion A in the width direction of the cuff body 101.

<4. Properties of each component constituting the pulse wave component>
Next, the shape of the pulse wave component detected by the pulse wave detecting air bag 105 under the triple cuff configuration will be described with reference to FIG. FIG. 4 is a diagram schematically showing each component included in the pulse wave component PW detected under the triple cuff configuration.

As shown in FIG. 4, the pulse wave component PW superimposed in time series on the cuff pressure signal detected by the pulse wave detecting air bag 105 is mainly derived from the blood flow from the upstream side of the cuff body 101. The component W1 (hereinafter referred to as the W1 component) derived from a direct change in cuff pressure due to a change in intravascular volume due to blood flow, and a change in cuff pressure due to a change in intravascular volume due to reflection from a blood vessel on the downstream side of the cuff body 101 It is divided into derived components W2 (hereinafter referred to as W2 components).

The W1 component is a component W1-A (hereinafter referred to as a W1-A component) derived from a pressure change (a change in volume in the blood vessel) under the cuff body 101 in the width direction, that is, the cuff center A. 3, the pressure change (intravascular volume change) under the upstream portion in the width direction of the cuff body 101, that is, the portion B in FIG. 3 (hereinafter simply referred to as the cuff upstream portion B) attenuated by the sub air bag 107. The derived component W0 and the downstream portion in the width direction of the cuff body 101, that is, the component W1-C derived from the change in the intravascular volume under the portion C in FIG. 3 (hereinafter simply referred to as the cuff downstream portion C) Hereinafter, it can be considered as a W1-C component).

In general, in the decompression process, when the cuff pressure becomes lower than the systolic blood pressure, a blood flow flows, and a phenomenon in which blood flows from the upstream side to the downstream side in the cuff body 101 is observed. When it becomes lower, the W1 component is superimposed.

Of these, the W1-A component is easier to detect than the W0 component and the W1-C component because the pulse wave detection air bag 105 is attached to the cuff central portion A, and has a great influence on the shape of the W1 component. give.

On the other hand, the W0 component is greatly reduced because the cuff edge effect of the air bag 108 for ischemia is compensated by the sub air bag 107. Further, since it originates from a pressure change (intravascular volume change) in the upstream portion of the cuff body 101 in the width direction, it appears before the W1-A component.

The W1-C component is smaller than the W1-A component because the cuff downstream portion C is located downstream of the cuff central portion A. In addition, the opening and closing of the blood vessel under the cuff downstream portion C is substantially synchronized with the opening and closing of the blood vessel under the cuff central portion A, and there is no substantial time difference with respect to the appearance of the W1-A component.

On the other hand, since the W2 component is a reflection from the blood vessel on the downstream side of the cuff body 101 with respect to the blood flow from the upstream side, an amplitude peak appears depending on the timing at which the intravascular pressure on the downstream side becomes higher than the cuff pressure. Is delayed from the appearance of the peak of the amplitude of the W1 component. In general, the influence of the shape of the W2 component on the shape of the entire pulse wave component is smaller than the influence of the shape of the W1 component (combination of the W1-A component and the W1-C component). Further, in the decompression process, when the cuff pressure approaches the diastolic blood pressure value, the intravascular pressure on the downstream side of the cuff body 101 has sufficiently recovered to the state before ischemia. Reflection is virtually eliminated. Therefore, in the pulse wave component detected when the cuff pressure is close to the diastolic blood pressure value, the W2 component is substantially eliminated.

<5. Change in W1-A component of pulse wave component during decompression process>
Next, changes in the size and shape of the W1-A component during the decompression process among the pulse wave components formed by the above components will be described with reference to FIG.

FIG. 5 is a diagram schematically showing how the W1-A component derived from the change in the intravascular volume under the cuff central portion A is generated and changed during the process of reducing the cuff pressure.

In graph 1, the horizontal axis indicates the elapsed time when the cuff pressure is reduced at a constant pressure reduction rate, and the vertical axis indicates the intravascular external pressure difference (intravascular pressure-cuff pressure). Graph 1 shows the cuff central portion A below the cuff derived from the invasive waveform (intravascular pressure change) at each time point in the elapsed time when the invasive waveform (intravascular pressure change) is simplified by a triangular waveform. It shows the change in the blood pressure difference between the blood vessels inside and outside (the same triangular waveform as the open waveform).

Graph 2 represents the change in the intravascular volume at each time point according to the change in the intravascular external pressure difference, with the vertical axis as the intravascular volume.

In addition, on the left side of the vertical axis of the intravascular / external pressure difference, the relationship between the intravascular / external pressure difference and the intravascular volume that converts the change in the intravascular external pressure difference (graph 1) into the change in the intravascular volume (graph 2) is shown. It is shown as graph 3 with the internal volume.

The relationship between the intravascular external pressure difference and the intravascular volume in Graph 3 is simplified by paying attention to the tendency of the intravascular volume to suddenly change (rapid increase or decrease) when the intravascular external pressure difference is near zero. As shown in the graph 3, in the process of increasing or decreasing the intravascular external pressure difference, the intravascular volume is between the completely closed state (intravascular volume 0) and the fully open state (intravascular volume Vmax). Bends at two points, V0 and V1. That is, the relationship between the intravascular external pressure difference and the intravascular volume is a line graph composed of a steep straight line between V0 and V1, and straight lines with gentle gradients of V0 or less and V1 or more.

This is because the blood vessel is crushed by its own weight (intravascular volume V0) at the position where the intravascular external pressure difference is 0, but when the intravascular external pressure difference changes to a positive value from this position, the intravascular volume suddenly increases. This is because after the blood vessel reaches a sufficiently open state (intravascular volume V1), it gradually increases (towards the maximum intravascular volume Vmax) with respect to the change in the intravascular external pressure difference. Also, when the intravascular external pressure difference changes from a position of 0 to a negative value, the intravascular volume gradually decreases (goes toward the intravascular volume 0).

In the graph 3, since a straight line approximates between V0 and V1 where the intravascular volume changes steeply, the rate of change of the intravascular volume is constant during this period. The ratio of the change at the position where the intravascular external pressure difference is 0 (the position of the intravascular volume V0) is maximized.

As described above, the tendency of the intravascular volume to suddenly change (sudden increase) when the intravascular external pressure difference is close to 0 depends on the degree of extensibility of the subject's blood vessels, but the tendency itself is generalized. It is considered possible.

Of the time points of the cuff pressure reduction process (elapsed time) shown in graph 1, a is the change in the internal / external pressure difference (triangle waveform) at the time when the cuff pressure is equal to the systolic blood pressure value, and b is the cuff pressure. A change in the intravascular external pressure difference at a time point approximately at the center of the systolic blood pressure value and the diastolic blood pressure value, and c indicates a change in the intravascular external pressure difference when the cuff pressure is equal to the diastole blood pressure value.

Changes in the intravascular external pressure difference (triangular waveform) a, b, c at each time point with respect to the elapsed time are the peak (peak points) of the systolic blood pressure value in the open waveform (intravascular pressure change) (i.e., It originates from the early diastole of the heart H, and the downward apex (bottom point) is in the portion of the diastolic blood pressure value (ie, early systole of the heart H) in the blood pressure waveform (intravascular pressure change) It comes from.

When the change in the intravascular external pressure difference of the graphs a, b, and c is converted into the change in the intravascular volume using the relationship between the intravascular external pressure difference and the intravascular volume in the graph 3, a ′, b in the graph 2 respectively. ', C'. In a ′, b ′, and c ′, the initial position of the heart H in the systolic period (two places before and after) is indicated by white circles. This corresponds to the downward apex (bottom point) of the open waveform (change in intravascular pressure). A component (indicated by a thick line) shown between the initial positions of the heart H in the systolic period (two locations before and after) is the W1-A component.

That is, graph 2 shows how the W1-A component changes at each point in the cuff pressure reduction process (elapsed time).

For the W1-A components (a change in intravascular volume) of a ′, b ′, and c ′, dots (black circles) indicate the positions where the intravascular external pressure difference becomes 0 preceding the amplitude peak point. In the W1-A component of a ′ (intravascular volume change), the peak point of the amplitude corresponds to the position where the intravascular external pressure difference is 0, and this position is indicated by a dot. The position where the intravascular external pressure difference indicated by the dots a ′, b ′, and c ′ is 0 is actually a portion where the intravascular volume suddenly increases (rapidly increases) (the rapid increase point in the first half of the W1-A component) And the peak point of the slope).

Furthermore, with respect to the W1-A components of a ′, b ′, and c ′, the position where the intravascular volume that occurs behind the peak point is minimized is also indicated by dots. It is known that the position where the intravascular volume that occurs after the peak point of the W1-A component is minimized is substantially equal to the position of the actual downward peak point (bottom point) of the pulse wave component. Therefore, hereinafter, the position where the intravascular volume that occurs behind the peak point of the W1-A component is minimized is referred to as the bottom point of the W1-A component.

In graph 2, it is a portion where the intravascular volume rapidly increases with the W1-A component (the rapid increase point in the first half of the W1-A component and the peak point of the inclination) [intravascular external pressure difference indicated by dots is The position that becomes 0] indicates a time (time difference) delayed from the initial position of the systole preceding the W1-A component by t, and one period of the pulse wave component by T. Here, one period T of the pulse wave component is substantially constant during the period of blood pressure measurement.

t is the time (time difference) of the delay from the bottom point of the preceding W1-A component of the rapidly increasing portion of the W1-A component of interest (the sharp increase point in the first half and the peak point of the magnitude of the slope), that is, It is considered that the time difference of appearance from the preceding bottom point (of the W1-A component) of the peak point (sudden rising point) of the magnitude of the inclination is shown.

As shown by a ′, b ′, and c ′ in graph 2, the time difference t decreases as the cuff pressure approaches the systolic blood pressure value from the systolic blood pressure value.

Here, since one cycle T of the pulse wave component is substantially constant during the period of blood pressure measurement, the phase difference 2π of the appearance from the preceding bottom point of the peak point of the slope (the rapidly rising point). Similarly, (t / T) decreases as the cuff pressure approaches the systolic blood pressure value from the systolic blood pressure value.

Then, as indicated by c ′ in the graph 2, at the time when the cuff pressure becomes equal to the diastolic blood pressure value, the preceding bottom point of the W1-A component and the magnitude of the inclination are obtained under this simplified graph. The peak point (a sudden rise point) and the early systolic period occur simultaneously, and t = 0.

From these facts, the following two features can be found for the actual W1-A component.

・ The delay from the bottom point (time difference t or phase difference 2π (t / T)) of the portion where the amplitude of the W1-A component suddenly increases (peak point of the magnitude of the inclination) causes the cuff pressure to approach the diastolic blood pressure value As it gets smaller.

The shape of the W1-A component appears when the cuff pressure becomes smaller than the pressure of the systolic blood pressure value.

<6. Characteristics of pulse wave component>
As mentioned above, the pulse wave component PW is divided into each component, and the simplified examination content about the W1-A component is shown. However, in actuality, the pulse wave component PW is separated into the W1-A component, the W0 component, and the like. Without being detected, each pulse wave component is detected via the pulse wave detection air bag 105 as a single pulse wave component.

However, as already described, the W0 component affects the rising portion, and the W1-A component greatly affects the shape of the W1 component of the pulse wave component superimposed on the cuff pressure. Further, the W2 component of the pulse wave component is generally smaller than the W1 component, and disappears when the cuff pressure approaches the diastolic blood pressure value.

Therefore, the following three characteristics can be found as the characteristics of the detected pulse wave component.

The delay from the bottom point (time difference t or phase difference 2π (t / T)) of the portion where the amplitude of the pulse wave component increases rapidly (peak point of the magnitude of the inclination) is as the cuff pressure approaches the diastolic blood pressure value. Get smaller.

・ The shape between the portion where the amplitude of the pulse wave component suddenly increases (peak point of the magnitude of the inclination) and the bottom point follows the shape from the vicinity of the peak point of the amplitude of the W0 component in FIG. 4 to the bottom point.

The portion where the amplitude of the pulse wave component increases rapidly (the peak point of the slope) is the overlapping portion of the W0 portion and the W1-A portion of FIG. 4 when the cuff pressure falls below the systolic blood pressure value. Greatly changes to the peak point side of the amplitude of the W0 component.

<7. Determination method of blood pressure value>
Therefore, by raising the cuff pressure to a value sufficiently higher than the systolic blood pressure value and then gradually reducing the cuff pressure to a value not more than the diastolic blood pressure value at a constant speed, the above-mentioned characteristics of the pulse wave component are used. The blood pressure value can be determined as follows.

-The cuff pressure at the time when the time difference between the bottom point that occurs prior to the peak point of the amplitude of the pulse wave component and the peak point (abrupt rise point) of the magnitude of the inclination becomes smaller than the predetermined threshold Th and becomes almost constant is expanded. The diastolic blood pressure value (“diastolic blood pressure value determination method 1”).

The displacement from the peak point (abrupt increase point) of the magnitude of the slope of the bottom point that occurs before or after the peak point of the amplitude of the pulse wave component (the difference in amplitude value from the bottom point to the sudden increase point) is a predetermined threshold Th The cuff pressure at which the pressure becomes smaller and almost constant is used as the diastolic blood pressure value (“diastolic blood pressure value determination method 2”).

-Check the value of the time difference between the bottom point that occurs prior to the peak point of the amplitude of the pulse wave component and the peak point of the magnitude of the slope (the sudden rise point) from the point where the cuff pressure is higher than the systolic blood pressure value, The cuff pressure value at the time when a large change having no continuity of values between pulse wave components is taken as the systolic blood pressure value (“systolic blood pressure value determination method 1”).

<8. Calculation method of peak point of sharpness (seep rise point)>
Next, a method for calculating the peak point (sudden rise point) of the magnitude of the slope to be calculated when determining the systolic blood pressure value and the diastolic blood pressure value according to the blood pressure value determining method will be described. FIG. 6A is a diagram showing a pulse wave component superimposed on a cuff pressure signal detected when the cuff pressure is between the systolic blood pressure value and the diastolic blood pressure value.

6A, Pe represents the peak point of the amplitude of the pulse wave component PW, and B1 represents the bottom point generated prior to the peak point Pe of the amplitude of the pulse wave component.

D indicates each pulse wave data constituting the pulse wave component. For example, D ₂₀ is the _20th pulse wave data among the pulse wave data between the bottom point B1 and the peak point Pe. Represents.

A indicates a regression line calculated based on a plurality of continuous pulse wave data. For example, A ₂₀ indicates three continuous pulse wave data (D ₂₀ , D including the _20th pulse wave data). ₂₁ , D ₂₂ ).

Similarly, A ₅₀ includes a regression line of three consecutive pulse wave data (D ₅₀ , D ₅₁ , D ₅₂ ) including the _50th pulse wave data, and A ₈₀ includes the 80th pulse wave data. , Regression lines of three continuous pulse wave data (D ₈₀ , D ₈₁ , D ₈₂ ) are respectively shown.

In this way, m pieces of pulse wave data between the bottom point B1 and the peak point Pe (m = 3 in the example of FIG. 6A) are sequentially extracted, the regression line is calculated, and the slope is obtained. It is possible to accurately calculate the magnitude of the inclination between the point B1 and the peak point Pe.

FIG. 6B is a diagram showing a fluctuation (slope fluctuation curve) of the slope of the regression line in each pulse wave component when the cuff pressure value is in the vicinity of the systolic blood pressure value or less. In FIG. 6B, the horizontal axis represents each pulse wave data point from the bottom point B1 to the peak point Pe, and the vertical axis represents the slope Ar of the regression line calculated at each pulse wave data point. There are a plurality of pulse wave components superimposed on the cuff pressure signal in the decompression process, and since the inclination fluctuation curves are calculated mainly for the pulse wave components of W0 and W1, the inclination fluctuation curve is the maximum inclination of the two pulse waves. (In the example of FIG. 6B, as a preferable example, five slope fluctuation curves 611 to 615 are displayed based on the pulse wave components 601 to 605. Note that the slope fluctuation curves indicate the sampling rate. Thus, it may be a curve obtained from 2 to 10 points, and may be a regression line between 10 ms and several tens of ms).

As shown in FIG. 6B, when the cuff pressure is between the systolic blood pressure value and the diastolic blood pressure value and is close to the systolic blood pressure value, there are two peak points of the slope variation curve (see 612 to 614). ). When the cuff pressure is higher than the systolic blood pressure, since the W1 component is not superimposed on the pulse wave component PW, there is only one portion where the slope rapidly increases between the bottom point B1 and the peak point Pe ( This is because when the cuff pressure becomes lower than the systolic blood pressure and the W1 component is superimposed, there are two portions where the slope rapidly increases between the bottom point B1 and the peak point Pe (see FIG. 4). This is because the W0 component appears before the W1-A component as described, and the slope rapidly increases at two points, the time when the W0 component appears and the time when the W1-A component appears. To 604). Among these points, the second peak point corresponds to the above-mentioned sudden rise point. Therefore, the time difference from the bottom point B1 of the second peak point of the slope fluctuation curve is t.

<9. Blood pressure value calculation process>
Next, the flow of blood pressure value calculation processing executed according to the blood pressure value determination method described above will be described with reference to FIGS. 7A and 7B.

In step S701, “0” is substituted for a count value p for counting the number of pulse wave components superimposed in time series on the cuff pressure signal, and the number of data points of pulse wave data constituting each pulse wave component is counted. “1” is assigned to the count value n.

In step S702, among the pulse wave data constituting the pulse wave component superimposed on the cuff pressure signal detected in the decompression process, pulse wave data D _{n + 1} to D _{n + q} (q is the pulse wave data to be processed). This is a value indicating the number of data points. For example, when the sampling interval is 4 msec, the value is greater than 50), and is stored in a pulse wave analysis buffer (not shown).

In step S703, a convex change is detected from the pulse wave data (D _{n + 1} to D _{n + q} ) stored in the pulse wave analysis buffer, and the peak point Pe is specified.

In step S704, it is determined whether or not the peak point Pe is specified in step S703 (whether or not the peak point Pe is included in the pulse wave data Dn _{+ 1} to Dn _{+ q} ), and the peak point Pe is not specified. If it is determined that, the count value n is incremented in step S708, and the process returns to step S702.

On the other hand, if it is determined in step S704 that the peak point Pe has been specified, the process proceeds to step S705, and the bottom point B1 is determined from the pulse wave data (D _{n + 1} to D _{n + q} ) stored in the pulse wave analysis buffer. Identify.

In step S706, it is determined whether or not the bottom point B1 is specified in step S705 (whether or not the bottom point B1 is included in the pulse wave data Dn _{+ 1} to Dn _{+ q} ), and the bottom point B1 is not specified. If it is determined that, the count value n is incremented in step S709, and the process returns to step S702.

On the other hand, if it is determined in step S706 that the bottom point B1 has been specified, the process proceeds to step S707, and the count value p indicating the number of pulse wave components is incremented.

In step S710, an inclination variation curve calculation process is executed for the pulse wave data group (pulse wave component) currently stored in the pulse wave analysis buffer using the specified peak point Pe and bottom point B1. Specifically, m pulse wave data consecutively extracted from pulse wave data included from the bottom point B1 to the peak point Pe, and a regression line is calculated based on the extracted m pulse wave data. Then, the slope value is stored in a slope fluctuation curve buffer (not shown). Details of the slope fluctuation curve calculation process will be described later.

In step S711, using the slope variation curve calculated in step S710 and the identified bottom point B1, the feature amount is calculated for the pulse wave data group (pulse wave component) currently stored in the pulse wave analysis buffer. Extract. Specifically, the peak point β is detected in the slope fluctuation curve from the bottom point B1 to the peak point Pe, and the time difference tp from the bottom point B1 to the peak point β is calculated. Moreover, Pp which is the cuff pressure at that time is read, and (tp, Pp) is stored as one set in a blood pressure value determination buffer (not shown). Details of the feature amount extraction processing will be described later.

In step S721 of FIG. 7B, it is determined whether or not the count value p indicating the number of pulse wave components exceeds N (N is a predetermined integer). If it is determined in step S721 that the count value p does not exceed N, the process proceeds to step S722, and a value obtained by adding the number of data q to the current count value n is substituted. Thereby, the count value n indicating the first pulse wave data of the pulse wave data group (pulse wave component) next to the pulse wave data group (pulse wave component) in which the peak point Pe and the bottom point B1 are specified this time is Will be set.

On the other hand, if it is determined in step S721 that the count value p has exceeded N, the process proceeds to step S723 to determine whether or not a systolic blood pressure value has been calculated. If it is determined in step S723 that the systolic blood pressure value has not yet been calculated, the process proceeds to step S725 to execute systolic blood pressure value determination processing.

In the diastolic blood pressure value determination process, when it is determined that the systolic blood pressure value has been reached from the feature amount extracted from the pulse wave data group (pulse wave component) currently stored in the pulse wave analysis buffer If the systolic blood pressure value is determined and it is determined that the systolic blood pressure value has not been reached, the process directly proceeds to step S727.

On the other hand, if it is determined in step S723 that the systolic blood pressure value has already been calculated, the process proceeds to step S724 to execute a diastolic blood pressure value determination process. In the diastolic blood pressure value determination process, when it is determined that the diastolic blood pressure value has been reached from the feature amount extracted from the pulse wave data group (pulse wave component) currently stored in the pulse wave analysis buffer If the diastolic blood pressure value is determined and it is determined that the diastolic blood pressure value has not been reached, the process directly proceeds to step S726.

In step S726, it is determined whether a diastolic blood pressure value has been calculated. If it is determined in step S726 that the diastolic blood pressure value has not yet been calculated, the process proceeds to step S727, and a value obtained by adding the number of data q to the current count value n is substituted. Thereby, the count value n indicating the first pulse wave data of the pulse wave data group (pulse wave component) next to the pulse wave data group (pulse wave component) in which the peak point Pe and the bottom point B1 are specified is set this time. Will be.

On the other hand, if it is determined in step S726 that the diastolic blood pressure value has been calculated, the blood pressure calculation process ends.

<10. Inclination fluctuation curve calculation process>
Next, details of the inclination fluctuation curve calculation process (step S710 in FIG. 7A) will be described. FIG. 8 is a flowchart showing the flow of the slope fluctuation curve calculation process.

In step S801, n is substituted into a count value r for counting the number of data points of pulse wave data included between the bottom point B1 and the peak point Pe.

In step S802, m points of pulse wave data used for calculating the regression line are extracted. Here, the pulse wave data of m points to be extracted are set as (D _r , D _{r + 1} ,... D _{r + m} ).

In step S803, a regression line is calculated from the m-point pulse wave data (D _r , D _{r + 1} ,... D _{r + m} ) extracted in step S802, and the slope Ar is obtained.

In step S804, it is determined whether or not the slope Ar has been obtained for all pulse wave data included between the bottom point B1 and the peak point Pe. If it is determined in step S804 that there is pulse wave data for which the slope Ar is not obtained, the process proceeds to step S805, and the count value r is incremented.

On the other hand, if it is determined in step S804 that the slope Ar has been obtained for all the pulse wave data, the process proceeds to step S806, and each pulse wave data from the bottom point B1 to the peak point Pe is taken on the horizontal axis, An inclination fluctuation curve (see FIG. 6B) having an inclination Ar on the axis is calculated, and the inclination fluctuation curve calculation process is terminated.

<11. Feature extraction process>
Next, details of the feature amount extraction processing (step S711 in FIG. 7A) will be described with reference to FIG. FIG. 9 is a flowchart showing the flow of the feature amount extraction process.

In step S901, a time point at which the differential value of the slope fluctuation curve becomes zero is extracted. In step S902, it is determined whether there are a plurality of time points extracted in step S901.

If it is determined in step S902 that there is only one point in time at which the differential value of the slope fluctuation curve becomes zero, the process proceeds to step S903. In step S903, the time point extracted in step S901 is α _r .

On the other hand, if it is determined in step S902 that there are a plurality of time points at which the differential value of the slope fluctuation curve becomes zero, the process proceeds to step S904. At step S904, the one of the plurality of time points extracted in step S901, the a second time and beta _r.

In step S905, the phase difference between the pulse wave component W1 and the pulse wave component W0 is calculated and extracted as the feature amount of the p-th pulse wave component. Specifically, the time difference t between the time point α _r or β _r extracted in step S903 or S904 and the bottom point B1 is calculated, and extracted as the feature amount of the p-th pulse wave component.

<12. Systolic blood pressure value determination process and diastolic blood pressure value determination process>
Next, details of the systolic blood pressure value determination process (step S725 in FIG. 7B) and the diastolic blood pressure value determination process (step S724 in FIG. 7B) will be described with reference to FIGS.

FIG. 10 is a diagram for explaining the systolic blood pressure value determining process and the diastolic blood pressure value determining process. The horizontal axis indicates the cuff pressure detected in the decompression process, and the vertical axis indicates the cuff pressure at each cuff pressure. It is the graph which took the feature-value (phase difference) calculated from each pulse wave component superimposed on the signal in time series.

As described above, the cuff pressure is depressurized at a constant rate during the depressurization process, and thus the depressurization is performed at a constant depressurization rate. In FIG. 1, there is a significant change (see reference numeral 1001). Therefore, the systolic blood pressure value can be determined by extracting the cuff pressure at the time point when the temporal change of the feature amount is maximized.

Also, as shown in FIG. 10, the feature quantity that has greatly changed in the systolic blood pressure value then gradually decreases as the cuff pressure is reduced, and is constant (threshold Th ( 3 ms / beat) or less) (see reference numeral 1002). Therefore, after the systolic blood pressure value is calculated, the diastolic blood pressure value can be determined by extracting the cuff pressure at the time when the feature amount first falls below the threshold value.

FIG. 11 is a flowchart showing the flow of the systolic blood pressure value determination process and the diastolic blood pressure value determination process.

As shown in 11A of FIG. 11, when the systolic blood pressure value determination process is started, in step S1101, it is determined whether or not the amount of change in the feature amount in the process of reducing the cuff pressure is greater than or equal to a predetermined value. In step S1101, it is determined that the amount of change in the feature amount of the current pulse wave component (p-th pulse wave component) with respect to the previous pulse wave component (p-1th pulse wave component) is not greater than or equal to a predetermined value. In this case, the systolic blood pressure value determination process is terminated.

On the other hand, in step S1101, if the current pulse wave component (p-th pulse wave component) is greater than or equal to a predetermined value, the amount of change in the feature amount with respect to the previous pulse wave component (p-1th pulse wave component) is greater than or equal to a predetermined value. If it is determined, the process proceeds to step S1102.

In step S1102, the cuff pressure corresponding to the current pulse wave component is read. In step S1103, the read cuff pressure is determined as the systolic blood pressure value, and then the systolic blood pressure value determining process is terminated.

As illustrated in 11B of FIG. 11, when the diastolic blood pressure value determination process is started, in step S1111, the feature amount of the current pulse wave component (p-th pulse wave component) is equal to or less than a predetermined threshold Th. It is determined whether or not.

If it is determined in step S1111 that the feature amount of the current pulse wave component is greater than the predetermined threshold Th, the diastolic blood pressure value determination process is terminated.

On the other hand, if it is determined in step S1111 that the feature amount of the current pulse wave component is equal to or less than the predetermined threshold Th, the process proceeds to step S1112 to read the cuff pressure for the current pulse wave component, and in step S1113 After the read cuff pressure is determined as the diastolic blood pressure value, the diastolic blood pressure value determination process is terminated.

<13. Blood pressure measurement process in blood pressure measurement device>
Next, the flow of the entire blood pressure measurement process in the blood pressure measurement device 100 including the blood pressure value calculation process (FIGS. 7A and 7B) will be described with reference to FIG.

FIG. 12 is a flowchart showing the flow of the entire blood pressure measurement process in the blood pressure measurement device 100. When the cuff body 101 is attached to the subject's upper arm and a measurement start switch 142 (not shown) is pressed, the blood pressure measurement process shown in FIG. 12 is started.

In step S1201, cuff pressure initialization processing is executed. Specifically, the opening area of the quick exhaust valve / constant speed exhaust valve 122 is fully opened, the on-off valve 116 is opened, each air bag is exhausted, and residual air in each air bag is exhausted. Furthermore, zero setting (initialization) of the pressure sensor 131 is performed.

When the quick exhaust valve / constant speed exhaust valve is closed by step S1201 and the preparation for pressurization to the cuff (blood-insufficing air bag, pulse wave detecting air bag, sub air bag) is completed, in step S1202, the pump 123 is turned on. The driving is started, and the driving is continued until the cuff pressure reaches a specified pressure that is about 20 to 30 mmHg higher than the expected systolic blood pressure value.

In step S1203, it is determined whether or not the cuff pressure P has reached the specified pressure. If it is determined that the cuff pressure P has reached, the process proceeds to step S1204 and the driving of the pump 123 is stopped.

In step S1205, the rapid exhaust valve / constant speed exhaust valve 122 starts constant speed exhaust. Specifically, the cuff pressure control unit 140 uses the cuff pressure signal from the pressure sensor 131 to vary the opening area of the rapid exhaust valve / constant speed exhaust valve 122 so that the decompression speed becomes 2 to 3 mmHg / sec. To reduce the pressure at a constant speed.

In step S1206, input of the cuff pressure signal from the pressure sensor 131 is started at a specified sampling rate, and sequentially stored in the work area for pulse wave analysis. In step S1207, it is determined whether or not the number of data points of the pulse wave data is stored more than a predetermined number. In step S1207, if the number of data points of the pulse wave data is equal to or less than the predetermined number, the process returns to step S1206. On the other hand, if it is determined in step S1206 that the number of data points of the pulse wave data is stored more than a predetermined number, the process proceeds to step S1208, and blood pressure value calculation processing is performed. Note that the details of the blood pressure value calculation processing have been described with reference to FIGS. 7A and 7B, and thus description thereof is omitted here.

When the blood pressure value calculation process ends in step S1207 and the diastolic blood pressure value is determined, in step S1208, the opening area of the rapid exhaust valve / constant speed exhaust valve 122 is fully opened and the on-off valve 116 is opened. The cuff body 101 is brought to atmospheric pressure.

In step S1209, the systolic blood pressure value and the diastolic blood pressure value determined in step S1207 are displayed on the liquid crystal display unit 137, and the blood pressure measurement process is terminated.

As is clear from the above description, in the blood pressure measurement device 100 according to the present embodiment, when calculating the systolic blood pressure value and the diastolic blood pressure value, the bottom point and the peak point of each pulse wave component are specified, and the bottom point The slope of the regression line of a predetermined number of pulse wave data between the peak point and the peak point is calculated. Furthermore, based on the fluctuation of the slope of the regression line from the bottom point to the peak point, the slope sharply rising point (the peak point of the magnitude of the slope, that is, the time when the slope differential value is zero) is extracted, A time difference between the slope rising point and the bottom point of the pulse wave component preceding the slope rising point is calculated, and this time difference is used as a phase difference between the pulse wave component W0 and the pulse wave component W1 to form a feature amount. did.

In this way, by calculating the regression line and calculating the slope of the regression line, the amount of air in the pulse wave detection system increases and the cuff pressure is lower than the systolic blood pressure. Even when the pulse wave generated on the cuff peripheral side at that time is attenuated, it is possible to accurately calculate the sudden rise point.

As a result, systolic blood pressure values and diastolic blood pressure values can be calculated with high accuracy.

[Second Embodiment]
In the first embodiment, the time difference tp is extracted as the feature amount. However, the present invention is not limited to this, and the delay rate obtained by dividing by one period of the pulse wave is calculated to calculate the feature amount. It is good also as a structure.

The present invention is not limited to the above embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to make the scope of the present invention public, the following claims are attached.

Claims

An air bag for ischemia that is laid on the side in contact with the blood pressure measurement site and compresses the entire blood pressure measurement site;
A sub-air bag that is laid on the side of the blood bag for measuring blood pressure that is in contact with the blood pressure measurement site and compresses the heart side of the blood vessel of the blood pressure measurement site;
A pulse wave detection air bag that is laid on the side of the blood bag for blood pressure measurement that is in contact with the blood pressure measurement site and detects a pulse wave at the center of the blood vessel of the blood pressure measurement site;
A blood pressure measurement device that detects a cuff pressure in a decompression process, in which a plurality of pulse wave components are superimposed in time series,
For each of the plurality of pulse wave components superimposed on the detected cuff pressure,
Identify the amplitude peak point and the bottom point that appears before the peak point,
Between the bottom point and the peak point, it sequentially extracts a predetermined number of pulse wave data, calculates the slope of the regression line for each extracted pulse wave data,
Obtain the variation of the slope between the bottom point and the peak point,
A calculating means for calculating a feature amount based on a time difference between the time point when the differential value of the fluctuation becomes zero and the bottom point;
Determining means for determining, as a systolic blood pressure value, the cuff pressure corresponding to the pulse wave component that maximizes the change between the pulse wave components of the feature amount calculated for each of the plurality of pulse wave components. A blood pressure measurement device characterized by that.
The calculating means includes
If there is one time point at which the differential value of the variation becomes zero, the feature amount is calculated based on the time difference between the time point and the bottom point,
2. The blood pressure according to claim 1, wherein when there are a plurality of time points at which the differential value of the fluctuation becomes zero, the feature amount is calculated based on a time difference between a second time point and the bottom point. measuring device.
3. The blood pressure measurement device according to claim 1, wherein the feature amount is a value of the time difference or a value obtained by dividing the time difference by a time of one cycle of the pulse wave component.
The determining means calculates the cuff pressure corresponding to the pulse wave component for which the calculated feature amount is initially equal to or less than a predetermined threshold among the pulse wave components after the systolic blood pressure value is determined, The blood pressure measuring device according to claim 1, wherein the blood pressure measuring device is determined as a value.
The determining means determines the cuff pressure corresponding to the pulse wave component for which the attenuation change of the calculated feature value is equal to or less than a predetermined threshold among the pulse wave components after the systolic blood pressure value is determined, The blood pressure measuring device according to claim 1, wherein the blood pressure measuring device is determined as a blood pressure value.
An air bag for ischemia that is laid on the side in contact with the blood pressure measurement site and compresses the entire blood pressure measurement site;
A sub-air bag that is laid on the side of the blood bag for measuring blood pressure that is in contact with the blood pressure measurement site and compresses the heart side of the blood vessel of the blood pressure measurement site;
A pulse wave detection air bag that is laid on the side of the blood bag for blood pressure measurement that is in contact with the blood pressure measurement site and detects a pulse wave at the center of the blood vessel of the blood pressure measurement site;
A blood pressure measurement device that detects a cuff pressure in a decompression process, in which a plurality of pulse wave components are superimposed in time series,
For each of the plurality of pulse wave components superimposed on the detected cuff pressure,
Identify the amplitude peak point and the bottom point that appears before the peak point,
Between the bottom point and the peak point, it sequentially extracts a predetermined number of pulse wave data, calculates the slope of the regression line for each extracted pulse wave data,
Obtain the variation of the slope between the bottom point and the peak point,
A calculation means for calculating a feature quantity based on a displacement of an amplitude from the bottom point of the pulse wave component at the time when the differential value of the fluctuation becomes zero;
Determining means for determining, as a systolic blood pressure value, the cuff pressure corresponding to the pulse wave component that maximizes the change between the pulse wave components of the feature amount calculated for each of the plurality of pulse wave components. A blood pressure measurement device characterized by that.
An air bag for ischemia that is laid on the side in contact with the blood pressure measurement site and compresses the entire blood pressure measurement site;
A sub-air bag that is laid on the side of the blood bag for measuring blood pressure that is in contact with the blood pressure measurement site and compresses the heart side of the blood vessel of the blood pressure measurement site;
A pulse wave detection air bag that is laid on the side of the blood bag for blood pressure measurement that is in contact with the blood pressure measurement site and detects a pulse wave at the center of the blood vessel of the blood pressure measurement site;
A blood pressure value calculation method in a blood pressure measurement device for detecting a cuff pressure in a decompression process, in which a plurality of pulse wave components are superimposed in time series,
For each of the plurality of pulse wave components superimposed on the detected cuff pressure,
Identify the amplitude peak point and the bottom point that appears before the peak point,
Between the bottom point and the peak point, it sequentially extracts a predetermined number of pulse wave data, calculates the slope of the regression line for each extracted pulse wave data,
Obtain the variation of the slope between the bottom point and the peak point,
A calculation step of calculating a feature amount based on a time difference between the time when the differential value of the variation becomes zero and the bottom point;
Determining the cuff pressure corresponding to the pulse wave component that maximizes the change between the pulse wave components of the feature amount calculated for each of the plurality of pulse wave components as a systolic blood pressure value. The blood pressure value calculation method characterized by this.
An air bag for ischemia that is laid on the side in contact with the blood pressure measurement site and compresses the entire blood pressure measurement site;
A sub-air bag that is laid on the side of the blood bag for measuring blood pressure that is in contact with the blood pressure measurement site and compresses the heart side of the blood vessel of the blood pressure measurement site;
A pulse wave detection air bag that is laid on the side of the blood bag for blood pressure measurement that is in contact with the blood pressure measurement site and detects a pulse wave at the center of the blood vessel of the blood pressure measurement site;
A blood pressure value calculation method in a blood pressure measurement device for detecting a cuff pressure in a decompression process, in which a plurality of pulse wave components are superimposed in time series,
For each of the plurality of pulse wave components superimposed on the detected cuff pressure,
Identify the amplitude peak point and the bottom point that appears before the peak point,
Between the bottom point and the peak point, it sequentially extracts a predetermined number of pulse wave data, calculates the slope of the regression line for each extracted pulse wave data,
Obtain the variation of the slope between the bottom point and the peak point,
A calculation step of calculating a feature amount based on a displacement of an amplitude from the bottom point of the pulse wave component at the time when the differential value of the variation becomes zero;
Determining the cuff pressure corresponding to the pulse wave component that maximizes the change between the pulse wave components of the feature amount calculated for each of the plurality of pulse wave components as a systolic blood pressure value. The blood pressure value calculation method characterized by this.