JPH0467852B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to improvements in automatic blood pressure measuring devices.

BACKGROUND ART Conventionally, automatic blood pressure measuring devices have been provided that automatically measure the blood pressure value of a living body by compressing a part of the living body with a compression device such as a cuff.
Such an automatic blood pressure measuring device generally uses a pulse sound sensor to detect pulse sounds (so-called Korotkoff sounds) generated from a part of the living body compressed by a compression device.
The K-sound method determines the blood pressure value based on the generation and disappearance of the pulse sound, or the pressure vibration wave (pulse wave) of the cuff that is generated in synchronization with the pulse of the living body is detected. An oscillometric system that determines blood pressure values based on changes in size is known.

An example of a K-sound type automatic blood pressure measuring device is the one described in Japanese Patent Application Laid-open No. 108537/1983, and an example of an automatic blood pressure measuring device using an oscillometric method is the one described in Japanese Patent Application Laid-Open No. 16730/1983. This is what is described in .

Problems to be Solved by the Invention However, as described above, in automatic blood pressure measurement devices, blood pressure values may not be obtained accurately due to noise, and blood pressure values determined based on pulse sounds or pulse waves may not be accurate. It has been difficult to obtain sufficiently high reliability of the value.

On the other hand, the inventors of the present invention have repeatedly researched blood pressure measuring devices using two methods, the K-sound method and the oscillometric method, as described above. We discovered that the nature of noise that causes a decline in blood pressure measurement accuracy differs between blood pressure measurement devices. In other words, with the K-sound method, audible sounds with relatively high frequencies, such as the rustling of the cuff or the subject's clothes, sounds generated by the joints of the living body, or noise in the measurement environment, tend to mix in as noise from the microphone. , an oscillometric blood pressure measuring device,
For example, 0.5 that occurs due to the bending of the arm of the person being measured, which affects the pressure fluctuation of the compression device.
It was discovered that pressure vibrations with a relatively low frequency of about 4 Hz are likely to be mixed in as noise.

Due to the noise that affects blood pressure measurement using the K-sound method and the noise that affects blood pressure measurement using the oscillometric method, the measurement accuracy of blood pressure measurement using the conventional K-sound method or oscillometric method alone is poor. was not obtained sufficiently.

The present invention was made based on this knowledge, and its purpose is to determine blood pressure abnormalities caused by noise specific to the K-sound method or the oscillometric method. An object of the present invention is to provide a blood pressure measuring device that can obtain high reliability regardless of noise.

Means for Solving the Problems The gist of the present invention to achieve the above object is to compress a part of a living body with a compression device, as shown in the claim correspondence diagram of FIG. An automatic blood pressure measuring device that automatically measures the blood pressure value of a living body, which (a) detects a pulse sound generated from a part of the living body, and detects the blood pressure of the living body based on the generation and disappearance of the pulse sound. (b) detecting a pressure vibration wave generated in the compression device in synchronization with the pulsation of the living body, and determining the pressure vibration value based on a change in the magnitude of the pressure vibration wave; a second blood pressure determining means for determining the blood pressure value of the living body; and (c) a blood pressure value of the first blood pressure value determined by the first blood pressure determining means and the second blood pressure value determined by the second blood pressure determining means. and a determination means for determining, based on the difference, that one of the first blood pressure value and the second blood pressure value is in an abnormal state of blood pressure value based on a pre-stored judgment reference blood pressure value difference.

In this way, the determination means determines the first blood pressure value determined by the first blood pressure determination means based on the generation and disappearance of pulse sounds, and the second blood pressure determination means based on the pressure vibration wave of the compression device. Based on the blood pressure difference between the second blood pressure value and the second blood pressure value determined in advance, it is determined that one of the first blood pressure value and the second blood pressure value is abnormal based on a pre-stored judgment reference blood pressure difference. Ru.

Effects of the Invention Since the K-sound method and the oscillometric method have different types of noise that affect blood pressure measurement, it is possible to detect whether one of two types of blood pressure values detected simultaneously in a living body is an erroneous measurement due to noise. However, the other measurement value is very often normal. In the blood pressure measurement device of the present invention, it is determined that one of the blood pressure values is abnormal based on the difference between the first blood pressure value and the second blood pressure value obtained by both blood pressure measurement methods. It becomes possible to accurately detect erroneous measurements of blood pressure values, and high reliability of the blood pressure measuring device can be obtained.

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

FIG. 2 is a diagram showing the control circuit of the automatic blood pressure measuring device of this embodiment, and 10 is the compression device of this embodiment, which is a cuff that is wrapped around the upper arm of the living body. The cuff 10 includes a pressure sensor 12 and an electric pump 1.
4. A slow exhaust valve 18 equipped with a throttle 16 and a rapid exhaust valve 20 are connected via piping 22, respectively. Pressure sensor 12 supplies a pressure signal SP representative of the pressure within cuff 10 to low pass filter 24 and high pass filter 26. low pass filter 2
4 outputs a cuff pressure signal SK representing the pressure (cuff pressure) P of the cuff 10 via the A/D converter 28 by discriminating the static pressure included in the pressure signal SP.
Supplies to CPU30. The high pass filter 26 is
For example, by passing a signal having a frequency component of about 0.1 to 10 Hz and discriminating the pulse wave signal included in the pressure signal SP, a pulse wave signal SM representing a pulse wave is generated.
is supplied to the CPU 30 via the A/D converter 32. This pulse wave is a pressure vibration wave of the cuff 10 that is generated in synchronization with the subject's heartbeat. Therefore, the pressure sensor 12 and the high-pass filter 26 constitute the pulse wave sensor of this embodiment.

On the other hand, inside the cuff 10 there is a microphone 36.
is provided. The microphone 36 detects pulse sounds (Korotkoff sounds) generated from the upper arm of the subject and supplies a pulse sound signal SO representing the pulse sounds to the band filter 38 . In this embodiment, the microphone 36 functions as a pulse sound sensor. The band filter 38 passes a signal having a frequency component of, for example, about 30 to 80 Hz, and supplies the passed pulse sound signal SO to the CPU 30 via the A/D converter 40.

The CPU 30 connects to the ROM via the data bus line.
42, RAM 44, display 46, and output interface 48, and executes signal processing while utilizing the storage function of RAM 44 according to a program stored in advance in ROM 42, Valve 18 and quick exhaust valve 20
control. Further, the CPU 30 executes a series of blood pressure measurement operations, and generates a pulse wave signal SM and a cuff pressure signal.
The blood pressure value is determined by the oscillometric method based on the SK etc., and the blood pressure value is determined by the K sound method based on the pulse sound signal SO etc., and the blood pressure values obtained by both methods are displayed on the display 46.

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

First, when a power source (not shown) is turned on, it is determined in step S1 whether or not the start button 50 is operated. If the start push button 50 is not operated, step S1 is repeatedly executed and a standby state is entered, but if it is operated, step S2 is executed and both the slow exhaust valve 18 and the rapid exhaust valve 20 are closed. At the same time, the electric pump 14 is activated. In the following step S3, the cuff pressure P is set to a predetermined constant target cuff pressure.
It is determined whether P _n has been reached. This target cuff pressure P _n is a pressure that is sufficiently higher than the systolic blood pressure value of the living body, for example, a value of about 180 mmHg. Cuff pressure P
If it is determined that the cuff pressure P has not yet reached the target cuff pressure P _n , step S3 is repeatedly executed, but if the cuff pressure P has reached the target cuff pressure P _n , step S4 is executed and the electric The pump 14 is stopped, the slow exhaust valve 18 is opened, and the pressure in the cuff 10 is gradually lowered at a predetermined rate suitable for blood pressure measurement, for example, about 3 mmHg/sec. Next, by executing the blood pressure measurement routine in step S5, in the process of lowering the cuff pressure P, the systolic blood pressure value and diastolic blood pressure value are measured by the oscillometric method, and the systolic blood pressure value and the diastolic blood pressure value are measured by the K sound method, respectively. be measured.

FIG. 4 is a flowchart showing the operation of the blood pressure measurement routine at step S5. First, step SS1 is executed to determine whether the pulse wave signal SM has been detected. If this judgment is negative, the following steps SS2 and SS3 are skipped, but if the judgment of step SS1 is affirmative, in the blood pressure value determination routine of step SS2, the magnitude of the pulse wave represented by the pulse wave signal SM is An oscillometric blood pressure determination algorithm for determining systolic and diastolic blood pressure values based on changes in blood pressure is executed, thereby determining systolic and diastolic blood pressure values. Therefore, in this embodiment, the blood pressure value determination routine of step SS2 corresponds to the second blood pressure determination means. Next, these blood pressure values are stored in the RAM 44 by executing step SS3. Next, step SS
4 is executed to determine whether the pulse sound signal SO is detected. If this judgment is denied, subsequent steps SS5 and SS6 are skipped, but if it is affirmed, in the blood pressure value determination routine of step SS5, the systolic blood pressure value and A K-sound blood pressure determination algorithm for determining the diastolic blood pressure value is executed, thereby determining the systolic and diastolic blood pressure values. Therefore, in this embodiment, the blood pressure value determination routine at step SS5 corresponds to the first blood pressure determination means. Next, these blood pressure values are stored in the RAM 44 by executing step SS6.

After the blood pressure measurement routine is executed as described above, step S6 is executed to determine whether the measurements of the systolic blood pressure value and the diastolic blood pressure value by the oscillometric method and the K-sound method have been completed. Initially, this judgment was denied and Step S
5 is repeatedly executed, and when it is determined that the measurement of the systolic blood pressure value and the diastolic blood pressure value has been completed, the rapid exhaust valve 20 is opened in step S7, and the inside of the cuff 10 is rapidly evacuated.

Subsequently, in step S8, the first oscillometric method obtained as described above is
Based on the blood pressure difference between the blood pressure value of
It is now determined that one of the blood pressure values is abnormal. That is, in step S5, the oscillometric method and K
Among the two systolic blood pressure values and diastolic blood pressure values determined by the sound method, for example, the difference ΔP between the systolic blood pressure values of both methods is calculated, and this ΔP is the systolic blood pressure value in a general stable state of the living body. For example, 10mmHg, which is determined experimentally in advance corresponding to the maximum difference between the
It is determined whether or not the degree of determination reference value α is exceeded. If it is determined that ΔP exceeds α, the difference is determined by one of the systolic blood pressure values of both methods whose difference is ΔP and the diastolic blood pressure values corresponding to those systolic blood pressure values. systolic and diastolic blood pressure values are determined to be abnormal. Therefore, in this embodiment, step S8 corresponds to the determining means. Then, the subsequent step S9 is executed, and after the abnormality is displayed on the display 46, the steps S2 and subsequent steps are executed again to re-measure the blood pressure value. In this case, abnormal values will not be displayed. Further, if it is determined in step S8 that ΔP does not exceed α, the determined blood pressure value is normal, and by executing step S10, the first blood pressure value and the first blood pressure value The systolic blood pressure value and the diastolic blood pressure value, which are predetermined one of the two blood pressure values, are displayed.

As described above, in this embodiment, the noise generated due to the movement of the living body, the rubbing of the cuff 10, etc. affects the pulse wave and/or pulse sound, so that such pulse wave and pulse sound are If the difference ΔP between the first blood pressure value and the second blood pressure value determined by the oscillometric method and the K-sound method based on is larger than the judgment reference value α, step S8
In this case, either one of the first blood pressure value and the second blood pressure value is determined to be abnormal. Therefore, according to the blood pressure measuring device of the present embodiment, it is possible to accurately detect erroneous measurements of blood pressure values due to noise, and the reliability of blood pressure values can be significantly improved.

In the above-mentioned embodiment, an abnormality in the blood pressure value was determined based on the difference between the systolic blood pressure values of the oscillometric method and the K-sound method. There is no problem even if the judgment is based on the difference.

Furthermore, the degree of discrepancy between the blood pressure values of the oscillometric method and the K-sound method may be determined statistically. That is, as shown in FIG. 5, for example, while determining a regression line A of points indicating blood pressure values of the oscillometric method and the K-sound method detected within a certain period of time in a plurality of living organisms, this regression line is Standard deviation or regression line A
Find the standard deviation σ of the surroundings, and the difference in blood pressure values between the oscillometric method and the K-sound method, or the distance between the corresponding point and the regression line A, is the standard deviation σ.
It may be determined that there is an abnormality when the value exceeds the criterion value determined based on the above.

Further, in the above embodiment, step S8
After an abnormality is determined in step S9, the blood pressure value is remeasured by displaying the abnormality in step S9 and re-executing the operations after step S2, but only the abnormality display or only the remeasurement of the blood pressure value is performed. Alternatively, when an abnormality is determined in step S9, the blood pressure value that is not abnormal among the blood pressure values determined by both formulas may be displayed. To determine the non-abnormal blood pressure value, compare the blood pressure value with the smaller change compared to the previous blood pressure value, or the statistically determined criterion value, such as the moving average value. The blood pressure value on the smaller side may be selected.

In addition, in the above-described embodiment, blood pressure was measured during the slow blood pressure lowering process using the cuff 10, but the cuff 10
A method may also be used in which the blood pressure measurement is performed during the process in which the blood pressure is gradually increased from zero at a predetermined rate.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to claims of the present invention. Second
The figure is a block diagram illustrating a control circuit of an automatic blood pressure measuring device that is an embodiment of the present invention. FIG. 3 is a flowchart illustrating the operation of the circuit of FIG. 2. FIG. 4 is a flowchart illustrating the operation of the blood pressure measurement routine of FIG. FIG. 5 is a diagram showing the correlation between blood pressure values of the oscillometric method and the K-sound method. 10: Cuff (compression device), {12: Pressure sensor,
26: High pass filter} (pulse wave sensor), 36:
Microphone (pulse sensor), step S8:
Judgment means.

Claims (1)

[Scope of Claims] 1. An automatic blood pressure measuring device that automatically measures the blood pressure value of a living body by compressing a part of the living body with a compression device, the device comprising: a first blood pressure determining means for detecting and determining the blood pressure value of the living body based on the generation and disappearance of the pulse sound; detecting a pressure vibration wave generated in the compression device in synchronization with the pulse of the living body; a second blood pressure determining means for determining the blood pressure value of the living body based on a change in the magnitude of the pressure oscillation wave; and a first blood pressure value determined by the first blood pressure determining means and determined by the second blood pressure determining means. The first blood pressure value and the second blood pressure value are calculated based on the difference between the blood pressure value and the second blood pressure value stored in advance.
An automatic blood pressure measuring device comprising: a determining means for determining that one of the blood pressure values is abnormal.