JPH04122238A - Oscillometric type automatic hemadinamometer - Google Patents

Abstract

PURPOSE:To measure suitably a blood pressure value even if the body moves by arranging in parallel a first filter for taking out a pulse wave component varying with the pulsation of the artery and a second filter having a passing frequency higher than that of the first filter. CONSTITUTION:Not only the maximum and minimum blood pressure values SYS1, DIA1 are determined on the basis of the variation of accompanying variation of calf pressure P having the size of an artery signal SM taken out of a pressure signal SP by a firs band pass filter 26, but also the maximum and minimum pressure values SYS2, DIA2 are determined on the basis of the variation accompanying that of calf pressure P having the size of signal SA passing through a second band pass filter 30 having about 10-20Hz of pass frequency band higher than the pass frequency band of the first band pass filter 26 and capable of suitably removing noise due to the movement of a living body or the like. Preferred blood pressure values among the maximum and minimum blood pressure values SYS1, DIA1 and SYS2, DIA2 are indicated on a blood pressure indicator 46.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in automatic blood pressure measuring devices of the oscillometric type.

Conventional technology A compression device that compresses an artery in a living body and a pressure sensor that detects the compression pressure of the compression device are provided, and the technology is based on pressure signals sequentially output from the pressure sensor as the compression pressure of the compression device changes. Oscillometric type automatic blood pressure measurement devices that determine blood pressure values using blood pressure have been conventionally provided. In this oscillometric type automatic blood pressure measuring device, usually 1
A pulse wave component that fluctuates with the pulsation of the artery is extracted from the pressure signal through a bandpass filter having a relatively low pass frequency band of about ~10 Hz, and the magnitude of this pulse wave component changes with the change in the compression pressure. The blood pressure value is determined based on the blood pressure value.

Problems to be Solved by the Invention However, in such an oscillometric automatic blood pressure measuring device, when a body movement occurs in the living body during the process of changing the compression pressure by the compression device, the frequency of this body movement usually exceeds the bandpass filter. Since the frequency is low enough to be passed through, noise caused by body movement or the like may mix into the pulse wave component, making determination of the blood pressure value inaccurate.

The present invention was made against the background of the above circumstances, and its purpose is to provide an oscillometric automatic blood pressure measuring device that can suitably measure blood pressure even when there is body movement. It is in.

Means for Solving the Problems As a result of various studies based on the above circumstances, the inventor of the present invention found that the components of the pressure signal with a frequency higher than the pass frequency band of the bandpass filter are not affected by body movements. It has been found that not only is it difficult, but also that the magnitude changes with changes in the compression pressure, substantially similar to the pulse wave component, and that the blood pressure value can be suitably determined based on this.

The present invention was made based on such knowledge, and
The gist of this is that the above-mentioned oscillometric link type automatic blood pressure measuring device has the following characteristics: (a) As shown in the claim correspondence diagram of FIG. (b) a second filter that has a pass frequency higher than the pass frequency of the first filter, is provided in parallel with the first filter, and is supplied with the pressure signal; , (C) the first
(d) a 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 filter due to a change in the compression pressure; and (d) a magnitude of the pressure signal passed through the second filter. (e) a second blood pressure determining means for determining a blood pressure value based on a change accompanying a change in the compression pressure; and (e) based on the blood pressure values respectively determined by the first blood pressure determining means and the second blood pressure determining means. Display blood pressure value determining means for determining the blood pressure value to be displayed.

Operation and Effects of the Invention According to the oscillometric type automatic blood pressure measuring device having the above configuration, the pulse wave component extracted from the pressure signal by the first filter is calculated based on the change in magnitude accompanying the compression pressure change, as in the conventional case. In addition to the blood pressure value being determined by the first blood pressure determining means, the blood pressure value is determined based on the change in magnitude of the pressure signal that has passed through the second filter, which has a passing frequency higher than the passing frequency of the first filter, due to the change in compression pressure. However, the blood pressure value is determined by the second blood pressure determination means, and the blood pressure value to be displayed is determined by the display blood pressure value determination means based on both blood pressure values determined in this way. If the pulse wave component extracted from the pressure signal contains noise due to the body movement of the living body and the blood pressure value measured using the pulse wave component becomes abnormal, it is preferable to use the noise due to the body movement. A suitable measured blood pressure value can be displayed using the signal from the second filter, which can be removed. As a result, an oscillometric automatic blood pressure measuring device is provided which can suitably measure blood pressure values even if a body movement occurs during the compression pressure change process.

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

In FIG. 2, reference numeral 10 denotes a rubber bag-shaped cuff that is wrapped around and compresses the upper arm of a living body (not shown), and constitutes the compression device of this embodiment. The cuff 10 includes a pressure sensor 12. Rapid exhaust valve 14. Rate-limiting exhaust valve with throttle 16.
and an electric pump 18 are connected to each other via piping 20.

The pressure sensor 12 detects the pressure within the cuff 10 and outputs a pressure signal SP representing the pressure to a low-pass filter 22, and also outputs the pressure signal SP to a first band-pass filter 26 via an amplifier 24. The signals are outputted to the second bandpass filter 30 through the filters. The low-pass filter 22 detects the static pressure component in the pressure signal SP and transmits the cuff pressure signal SK representing the cuff pressure P (static pressure) to the A/D converter 3.
2 to the CPU 34. The first bandpass filter 26 is a conventionally provided one.
It has a passing frequency band of about ~10 Hz, detects a pulse wave component that fluctuates with the pulsation of an artery (not shown) from the pressure signal SP, and converts the pulse wave signal SM representing the pulse wave to the A/D converter 3.
6 to CPtJ34. The second band-pass filter 30 has a frequency band of 10 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.
It has a passing frequency band of approximately 207 to 207, and supplies the passed signal SA to the CPU 34 via the A/D converter 38. Therefore, in this embodiment, the first bandpass filter 26 constitutes a first filter, and the second bandpass filter 30 constitutes a second filter. In addition,
The reason why the amplifiers 24 and 28 are provided for each band pass filter 26 and 30 is that the gain in the second band pass filter 30 is usually about 1/10 to 1/100, and the gain in the first band pass filter 26 is different from that in the first band pass filter 26. Due to its small size in comparison.

The CPtJ34 connects to the ROM40 via the data bus line.
．． RAM42. The output ink face 44 and the blood pressure display 46 are connected to each other, and the input signals are processed according to a program prestored in the ROM 40 while utilizing the memory function of the RAM 42, and the rapid exhaust valve 14. Rate-limiting exhaust valve 16. and outputs a drive signal to the electric pump 18 via the output interface 44, while executing a series of blood pressure measurement operations based on the pulse wave signal SM and signal SA sequentially collected during the pressure process in the cuff 10, for example. Blood pressure values such as the systolic blood pressure value and the diastolic blood pressure value should be determined for each pulse wave signal SM and signal SA, and should be displayed based on the two types of blood pressure values determined for each pulse wave signal SM and signal SA. Determine the blood pressure value and display the blood pressure display 4
6.

Next, the operation of the oscillometric automatic blood pressure measuring device configured as described above will be explained according to the flowchart shown in FIG.

First, by executing step Sl, it is determined whether a starting switch (not shown) has been turned on.

If this judgment is negative, step Sl is repeatedly executed and the standby state is entered, but if it is affirmative, step S2 is executed, the rapid exhaust valve 14 and the rate-limiting exhaust valve 16 are closed, and the electric pump 18 is activated. As a result, pressure increase within the cuff 10 is started. In the subsequent step S3, it is determined whether the cuff pressure P has reached a target cuff pressure Pm higher than the predicted systolic blood pressure value of the living body. Steps S2 and S3 are repeatedly executed while the target cuff pressure Pm is not yet reached, but when the target cuff pressure Pm is reached, step 4 is executed, and the operation of the electric pump 18 is stopped and the rate-limiting exhaust valve 16 is When the cuff 10 is opened, rate-limiting pressure reduction within the cuff 10 is started. Then, in this rate-limiting blood pressure lowering process, a blood pressure determination routine in step S5 is executed.

In this blood pressure determination routine, for example, the systolic blood pressure value SYS, and the diastolic blood pressure value DIA, are determined, while the systolic blood pressure value 5YS
2 and the diastolic blood pressure value DIA2 is determined. Therefore, in this embodiment, the blood pressure determination routine of step S5 corresponds to the first blood pressure determination means and the second blood pressure determination means. FIG. 4(a) and FIG. 4(C) show the pulse wave signal SM
This section shows an example of the change in the magnitude of the signal SA and the change in the cuff pressure P, respectively.

In the following step S6, the blood pressure value 5YS1. It is determined whether DIAl, 5YS2, and DIA2 have been determined. If this judgment is negative, step S5 and step S6 are repeatedly executed, but if the judgment of step S6 is affirmative, step S
7 is executed, the quick evacuation valve 14 is opened, and the cuff 10 is opened.
By rapidly discharging the pressure inside the body and executing step S8, for example, the systolic blood pressure value SYS and the diastolic blood pressure value DIA (hereinafter referred to as
blood pressure value obtained by the first band-pass filter 26), systolic blood pressure value 5Y52, and diastolic blood pressure value (i D I A z
(hereinafter referred to as the blood pressure value obtained by the second band-pass filter 30) is determined to be displayed. That is, for example, if the blood pressure value obtained by the first band-pass filter 26 and the blood pressure value obtained by the second band-pass filter 30 are substantially the same, the blood pressure value obtained 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 determined by the second band-pass filter 30 may be determined as the blood pressure value to be displayed, or if one of the blood pressure values is abnormal, the other blood pressure value may be determined as the blood pressure value to be displayed. is determined as the blood pressure value to be displayed. Note that the determination as to whether or not the determined blood pressure value is abnormal is based on, for example, whether or not the blood pressure value is physiologically out of common sense, or whether there is an abnormality in the trend of the pulse wave signal SM or signal SA. It is done on the basis of crab. Once the blood pressure values to be displayed are determined in this manner, step S9 is executed, and the systolic blood pressure value and diastolic blood pressure value determined in step S8 are displayed on the blood pressure display 46.

In this 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 calculated 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 similar to the conventional one, due to the change in the cuff pressure P. In addition to determining the diastolic blood pressure value DIA, SYS and the diastolic blood pressure value DIA, the first bandpass filter 26
The signal S passed through 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 10 to 20 Hz, which can suitably remove noise caused by body movements of a living body.
The systolic blood pressure value 5ysz and the diastolic blood pressure value DIA2 are also determined based on the change accompanying the change in the cuff pressure P of magnitude A. Then, the systolic blood pressure value SY determined in this way
S, diastolic blood pressure value DIA, and systolic blood pressure value 5YS2 and diastolic blood pressure value A2, the blood pressure value which is suitable is displayed on the blood pressure display 46. If the blood pressure value measured using the pulse wave signal SM becomes abnormal due to noise caused by the body movement of the living body, the second pulse wave signal SM, which is not easily affected by body movement, etc. Signal S from bandpass filter 30
A suitable blood pressure value measured using A can be displayed. As a result, even if body movement occurs during the process of lowering the cuff pressure P, the blood pressure value can be suitably measured. Note that FIG. 4(b) and FIG. 4(d) are diagrams each showing an example of a change in the magnitude of the pulse wave signal SM and signal SA due to a change in the cuff pressure P when body movement occurs. In FIG. 4(b) based on the first band-pass filter 26, as can be seen from a comparison with FIG. 4(a), the influence of body movement is greater (appears), whereas In FIG. 4(d) based on the band-pass filter 30, as can be seen from a comparison with FIG. 4(C), almost no influence of body movement appears.

Further, according to this embodiment, since the second bandpass filter 30 serving as the second filter has a pass frequency band of about 10 to 207, noise caused by rubbing of the cuff 10, etc. can be suitably removed. As a result, the blood pressure value can be suitably measured not only due to body movements but also due to friction of the cuff 10.

This effect can be suitably obtained up to the upper limit of the pass frequency band of the second bandpass filter 30 of about 25 Hz.

Note that in the above embodiment, the first band pass filter 26
Although it has been explained that one of the two blood pressure values obtained by the second band-pass filter 30 is displayed on the blood pressure display 46, this is not necessarily necessary, and for example, the average value of both blood pressure values may be displayed. You can also do it. In short, the blood pressure value to be displayed may be determined based on the blood pressure values respectively determined by the first blood pressure determining means and the second blood pressure determining means.

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

Furthermore, in the embodiment described above, the first hand pass filter 26
Although amplifiers 24 and 28 are provided on the input side of the second bandpass filter 30, it is not necessary (for example, an amplifier 24, 28 is provided on the output side of the first bandpass filter 26 and the second bandpass filter 30). 24
．． 28 may be provided, or an A/D converter 38 may be provided.
When the resolution of the pressure signal SP is high, the pressure signal SP is amplified by a common amplifier and the pressure signal SP is
The configuration may be such that the signals are supplied to the band-pass filter 30, respectively.Furthermore, if the resolution of both the A/D converters 36 and 38 is high, it is also possible to configure the configuration without providing an amplifier at all.

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

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram. FIG. 2 is a block diagram showing the configuration of an oscillometric automatic blood pressure measuring device that is an embodiment of the present invention. FIG. 3 is a flowchart for explaining the operation of the automatic blood pressure measuring device shown in FIG. FIGS. 4(a) and (C) show pulse wave signals S sequentially collected by the automatic blood pressure measuring device of FIG. 1 in a state of no body movement.
FIG. 6 is a diagram illustrating an example of a change in M and a signal SA as a result of a change in cuff pressure P, respectively. FIGS. 4(b) and 4(d) show examples of changes in the pulse wave signal SM and signal SA, which are sequentially collected by the automatic blood pressure measuring device shown in FIG. FIG. 10: Cuff (compression device) 12: Pressure sensor

Claims (1)

[Scope of Claims] A compression device that compresses an artery in a living body, and a pressure sensor that detects the compression pressure of the compression device, wherein the pressure sensor sequentially outputs the pressure of the compression device in the process of changing the compression pressure of the compression device. An oscillometric automatic blood pressure measurement device that determines a blood pressure value based on a pressure signal, the device comprising: a first filter that extracts a pulse wave component that fluctuates with the pulsation of the artery from the pressure signal; a second filter having a pass frequency higher than the first filter and provided in parallel with the first filter and to which the pressure signal is supplied; a first blood pressure determining means that determines a blood pressure value based on a change accompanying the change; and a second blood pressure determining means that determines a blood pressure value based on a change in the magnitude of the pressure signal that has passed through the second filter that occurs due to a change in the compression pressure. An oscilloscope comprising: a blood pressure determining means; and a display blood pressure value determining means for determining a blood pressure value to be displayed based on the blood pressure values respectively determined by the first blood pressure determining means and the second blood pressure determining means. Metric type automatic blood pressure measuring device.