JP3058663B2 - Oscillometric type automatic blood pressure measurement device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement in an oscillometric type automatic blood pressure measurement device.

BACKGROUND ART A compression device that compresses an artery in a living body and a pressure sensor that detects a compression pressure of the compression device are provided.Based on a pressure signal sequentially output from the pressure sensor in a process of changing the compression pressure of the compression device. Conventionally, an oscillometric type automatic blood pressure measurement device that determines a blood pressure value has been provided. In this oscillometric automatic blood pressure measurement device, usually,
A pulse wave component that fluctuates along with arterial pulsation is extracted from the pressure signal through a bandpass filter having a relatively low pass frequency band of about 1 to 10 Hz, and the magnitude of the pulse wave component is caused by a change in the compression pressure. The blood pressure value is determined based on the change.

Problems to be Solved by the Invention However, in such an oscillometric type automatic blood pressure measurement device, when body movement occurs in a living body in the process of changing the compression pressure by the compression device, the frequency of the body movement is usually set by the band-pass filter. Since the frequency is low enough to allow passage, noise due to body movement or the like may be mixed into the pulse wave component, and the determination of the blood pressure value may be inaccurate.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an oscillometric type automatic blood pressure measurement device capable of suitably measuring a blood pressure value even when there is body movement. It is in.

Means for Solving the Problems The present inventor has made various studies based on the above circumstances, and as a result, of the pressure signal, a component of a frequency higher than a pass frequency band of the bandpass filter is hardly affected by body motion. In addition, it has been found that, in substantially the same manner as the pulse wave component, the magnitude changes with the change in the compression pressure, and the blood pressure value can be suitably determined based on the magnitude.

The present invention has been made based on such knowledge, and its gist is an oscillometric type automatic blood pressure measurement device as described above, as shown in the claim correspondence diagram of FIG. (A) a first filter having a pass frequency band of about 1 to 10 Hz and extracting a pulse wave component fluctuating with the pulsation of the artery from the pressure signal;
A second filter having a pass frequency band of about 10 to 25 Hz higher than the pass frequency of the first filter, provided in parallel with the first filter, and supplied with the pressure signal;
(C) first blood pressure determining means for determining a blood pressure value based on a change in the magnitude of the pulse wave component extracted by the first filter with a change in the compression pressure; and (d) passing through the second filter. A second blood pressure determining means for determining a blood pressure value based on a change in the magnitude of the pressure signal resulting from the change in the compression pressure; and (e) determined by the first blood pressure determining means and the second blood pressure determining means. Display blood pressure value determining means for determining a blood pressure value to be displayed based on the displayed blood pressure value.

According to the oscillometric type automatic blood pressure measurement device having the above-described configuration, the magnitude of the pulse wave component extracted from the pressure signal by the first filter having the pass frequency band of about 1 to 10 Hz as in the related art. In addition to the blood pressure value being determined by the first blood pressure determining means based on the change accompanying the compression pressure change of
Based on a change in the magnitude of the pressure signal passing through the second filter having a pass frequency band of about 10 to 25 Hz higher than the pass frequency of the first filter due to a change in compression pressure, the second
The blood pressure value is determined by the blood pressure determining means, and the blood pressure value to be displayed is determined by the display blood pressure value determining means based on the thus determined blood pressure values.
If the pulse wave component extracted from the pressure signal by the filter is mixed with noise due to body movement of the living body and the blood pressure value measured using the pulse wave component becomes abnormal, the noise due to the body movement etc. Can be displayed using the signal from the second filter that can preferably remove the blood pressure. As a result, an oscillometric type automatic blood pressure measurement device capable of suitably measuring a blood pressure value even when a body motion occurs in the compression pressure change process is provided.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 2, reference numeral 10 denotes a compression device of the present embodiment, which is a rubber bag-shaped cuff wound around an upper arm or the like (not shown) of the living body and pressing the same. The cuff 10 has a pressure sensor 1
2, a quick exhaust valve 14, a slow exhaust valve 16 provided with a throttle, and an electric pump 18 are connected via a pipe 20 respectively. The pressure sensor 12 detects the pressure in the cuff 10 and outputs a pressure signal SP representing the pressure to the low-pass filter 22, and outputs the pressure signal SP to the first band-pass filter 26 via the amplifier 24 and the amplifier 28. Via a second bandpass filter
Output to 30 respectively. The low-pass filter 22 detects a static pressure component in the pressure signal SP and provides a cuff pressure signal SK representing a cuff pressure P (static pressure) to the CPU 34 via the A / D converter 32. The first band-pass filter 26 is conventionally provided, has a pass frequency band of about 1 to 10 Hz, and has a pulse wave component that fluctuates with a pulsation of an artery (not shown) from the pressure signal SP. And provides a pulse wave signal SM representing the pulse wave to the CPU 34 via the A / D converter 36. The second band-pass filter 30 has a pass frequency band of about 10 to 20 Hz which is higher than the pass frequency band of the first band-pass filter 26 and higher than the frequency of normal body movement of the living body. A / D
The data is supplied to the CPU via the converter. Therefore, in the present embodiment, the first band-pass filter 26 constitutes a first filter, and the second band-pass filter 30 constitutes a second filter. The reason why the amplifiers 24 and 28 are provided for each of the band-pass filters 26 and 30 is that the gain in the second band-pass filter 30 is usually about 1/10 to 1/100 and Because it is smaller than the gain.

The CPU 34 is connected to the ROM 40, the RAM 42, the output interface 44, and the blood pressure display 46 via the data bus lines, respectively, and processes input signals in accordance with a program stored in the ROM 40 in advance while using the storage function of the RAM 42. A drive signal is output to the quick exhaust valve 14, the slow exhaust valve 16, and the electric pump 18 via the output interface 44, and a series of blood pressure measurement operations are performed to sequentially collect the blood pressure in the cuff 10, for example, during a pressure reduction process. The blood pressure values such as the systolic blood pressure value and the diastolic blood pressure value are determined for each pulse wave signal SM and signal SA based on the pulse wave signal SM and the signal SA, and are determined for each pulse wave signal SM and signal SA. The blood pressure value to be displayed is determined based on the two types of blood pressure values and displayed on the blood pressure display 46.

Next, the operation of the oscillometric type automatic blood pressure measurement device configured as described above will be described with reference to the flowchart of FIG.

First, by executing step S1, it is determined whether a start switch (not shown) has been turned ON. If this determination is denied, step S1 is repeatedly executed to enter the standby state, but if affirmed, step S2 is executed, the quick exhaust valve 14 and the slow exhaust valve 16 are closed, and the electric pump 18 When activated, the pressure rise in the cuff 10 is started. In the following step S3, the cuff pressure P is a target cuff pressure higher than the expected systolic blood pressure value of the living body.
It is determined whether Pm has been reached. While the target cuff pressure Pm has not yet been reached, Steps S2 and S3 are repeatedly executed. However, when the target cuff pressure Pm has been reached, Step 4 is executed, the operation of the electric pump 18 is stopped, and the slow exhaust valve is operated. By opening 16, the slow pressure reduction in the cuff 10 is started. Then, in such a slow pressure drop process, a blood pressure determination routine of step S5 is executed.

In this blood pressure determination routine, for example, a systolic blood pressure value SYS in accordance with a well-known algorithm based on a change in the magnitude of the pulse wave signal SM collected during the slow down period of the cuff 10 with a change in the cuff pressure P. ₁ and the systolic blood pressure value DIA ₁ are determined, and the systolic blood pressure value is similarly determined based on the change in the magnitude of SA of the signal obtained in parallel with the pulse wave signal SM with the change in the cuff pressure P. SYS ₂ and systolic blood pressure value DIA ₂ are determined. Therefore, in the present embodiment, the blood pressure determining routine of step S5 corresponds to the first blood pressure determining means and the second blood pressure determining means. FIGS. 4 (a) and 4 (c) are diagrams illustrating examples of changes in the magnitude of the pulse wave signal SM and the signal SA with the change in the cuff pressure P, respectively.

In subsequent step S6, whether the blood pressure value _{SYS 1, DIA 1, SYS 2} , DIA 2 has been determined is determined in step S5. If this determination is denied, steps S5 and S6 are repeatedly executed.If the determination in step S6 is affirmed, step S7 is executed, the quick exhaust valve 14 is opened, and the inside of the cuff 10 is rapidly reduced. And the step
By S8 is performed, for example, systolic blood pressure SYS ₁ and the diastolic blood pressure value DIA ₁ determined in step S5 (hereinafter, referred to as a blood pressure value according to the first band-pass filter 26) systolic blood pressure value SYS ₂ and minimum The blood pressure value DIA ₂ (hereinafter referred to as the blood pressure value by the second bandpass filter 30) is determined. That is, for example, when the blood pressure value by the first band-pass filter 26 and the blood pressure value by the second band-pass filter 30 are substantially the same, the blood pressure value by the first band-pass filter 26 is determined as the blood pressure value to be displayed. However, if the blood pressure values are significantly different, the blood pressure value by the second bandpass filter 30 is determined as the blood pressure value to be displayed, or if one of the blood pressure values is abnormal, The other is determined as the blood pressure value to be displayed. The determination as to whether or not the determined blood pressure value is abnormal is made, for example, as to whether or not the blood pressure value is physiologically uncommon, or whether the pulse wave signal SM or the signal SA
Is performed based on whether there is an abnormality in the trend. When the blood pressure value to be displayed is determined in this way, step S9 is executed, and the systolic blood pressure value and the diastolic blood pressure value determined in step S8 are displayed on the blood pressure display 46. In the present embodiment, the step S8 corresponds to the display blood pressure value determining means.

As described above, according to the present embodiment, the systolic blood pressure value is determined based on the change in the magnitude of the pulse wave signal SM extracted from the pressure signal SP by the first band-pass filter 26 in accordance with the change in the cuff pressure P. In addition to the SYS ₁ and the diastolic blood pressure value DIA ₁ being determined, a pass of about 10 to 20 Hz which is higher than the pass band of the first band-pass filter 26 and which can suitably remove noise due to body movements of a living body, etc. The systolic blood pressure value SYS ₂ and the diastolic blood pressure value DIA ₂ are also determined based on a change in the magnitude of the signal SA that has passed through the second band-pass filter 30 having a frequency band with a change in the cuff pressure P. Then, the blood pressure values of preferred ones of this way the systolic blood pressure SYS ₁ and the diastolic blood pressure value DIA ₁ determined by the systolic blood pressure value SYS ₂ and the diastolic blood pressure value DIA ₂ is displayed on the blood pressure display 46 Therefore, for example, when the pulse wave signal SM from the first band-pass filter 26 is mixed with noise due to body movement of the living body and the blood pressure value measured using the pulse wave signal SM becomes abnormal, It is possible to display a suitable blood pressure value measured using the signal SA from the second band-pass filter 30 that is not easily affected by body motion and the like. As a result, the blood pressure value can be suitably measured even when body movement occurs in the process of lowering the cuff pressure P. FIGS. 4B and 4D show examples of changes in the magnitudes of the pulse wave signal SM and the signal SA with a change in the cuff pressure P when a body motion occurs. In FIG. 4B based on the first band-pass filter 26, the effect of body movement appears greatly as can be seen from FIG. In FIG. 4D based on the filter 30, almost no influence of the body movement appears as can be seen from FIG. 4C.

Further, according to the present embodiment, the second filter as the second filter
Since the band-pass filter 30 has a pass frequency band of about 10 to 20 Hz, noise due to rubbing of the cuff 10 and the like can be appropriately removed, and not only body movement but also rubbing of the cuff 10 occurs. The blood pressure value can be suitably measured. This effect is obtained when the upper limit of the pass frequency band of the second bandpass filter 30 is
Suitable up to about 25 Hz.

In the above-described embodiment, the first band-pass filter 26
It has been described that one blood pressure value of both blood pressure values by the second band-pass filter 30 is displayed on the blood pressure display 46. However, it is not always necessary to display the blood pressure value. Can also. In short, the blood pressure value to be displayed may be determined based on the blood pressure values determined by the first blood pressure determining means and the second blood pressure determining means, respectively.

Further, in the above-described embodiment, the first filter and the second filter are each configured by an analog filter, but may be configured by a digital filter by software.

In the above-described embodiment, the first bandpass filter 26
And amplifiers 24, 2 on the input side of the second bandpass filter 30.
8 are provided, but are not necessarily required. For example, amplifiers 24 and 28 may be provided on the output side of the first band-pass filter 26 and the second band-pass filter 30, or the A / D When the resolution of the converter 38 is high, the pressure signal SP may be amplified by a common amplifier and supplied to the first band-pass filter 26 and the second band-pass filter 30, respectively. / D
When the resolutions of the converters 36 and 38 are both high, it is possible to configure without providing any amplifier.

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

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims. FIG. 2 is a block diagram showing a configuration of an oscillometric type automatic blood pressure measurement device according to one embodiment of the present invention. FIG. 3 is a flow chart for explaining the operation of the automatic blood pressure measurement device of FIG. FIGS. 4 (a) and (c) show the first state in a state where there is no body movement.
Pulse wave signal sequentially collected by the automatic blood pressure measurement device in the figure
It is a figure which shows an example of the change accompanying change of the cuff pressure P of SM and signal SA, respectively. FIGS. 4 (b) and 4 (d) show examples of changes in the cuff pressure P of the pulse wave signal SM and the signal SA which are sequentially collected by the automatic blood pressure measurement device of FIG. FIG. 10: Cuff (compression device) 12: Pressure sensor 26: First bandpass filter (first filter) 30: Second bandpass filter (second filter) Step S5: (First and second blood pressure determining means) Step S8 : (Display blood pressure value determination means)

Claims (1)

(57) [Claims] 1. A compression device for compressing an artery in a living body, and a pressure sensor for detecting a compression pressure of the compression device, and a pressure sequentially output from the pressure sensor in a process of changing the compression pressure of the compression device. An oscillometric type automatic blood pressure measurement device that determines a blood pressure value based on a signal, having a pass frequency band of about 1 to 10 Hz, and a pulse wave component that fluctuates with the pulsation of the artery from the pressure signal. A first filter to be taken out, a second filter having a pass frequency band of about 10 to 25 Hz higher than the pass frequency band of the first filter, provided in parallel with the first filter, and supplied with the pressure signal, First blood pressure determining means for determining a blood pressure value based on a change in the magnitude of the pulse wave component extracted by the first filter with a change in the compression pressure; and a magnitude of a pressure signal passed through the second filter. A second blood pressure determining means for determining a blood pressure value based on a change accompanying the change of the compression pressure; and a display based on the blood pressure values respectively determined by the first blood pressure determining means and the second blood pressure determining means. An oscillometric type automatic blood pressure measurement device, comprising: a display blood pressure value determining means for determining a blood pressure value.