JPS6198235A - Hemomanometer apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a blood pressure measuring device that automatically measures the blood pressure of a subject, and particularly relates to a blood pressure measuring device that measures blood pressure based on Korotkoff sounds generated from arteries due to compression by a cuff. This paper relates to improvements in measuring devices.

Prior Art A cuff for compressing a part of a living body and a Korotkoff sound sensor installed on the cuff for detecting Korotkoff sounds, based on the Korotkoff sounds generated from arteries due to compression by the cuff. Specifically, blood pressure measuring devices have been widely known that measure blood pressure using the cuff pressure at the time of occurrence and disappearance of Korotkoff sounds associated with changes in cuff compression pressure as systolic blood pressure values and diastolic blood pressure values.

By the way, blood pressure is an important indicator of the state of physical health and is one of the basic information for medical decisions.
The measuring device is required to have high reliability. For this reason,
The above-mentioned blood pressure measuring device is usually equipped with a noise removal means such as a band-pass filter, which removes vibrations of frequency components different from the Korotkoff sound from the signal detected by the Korotkoff sound sensor, such as those caused by the body movement of the subject. The measurement accuracy of the device is improved by removing the noise generated during the measurement.

Problems to be Solved by the Invention However, such noise removal means cannot be installed.
Even in conventional blood pressure measuring devices, if noises similar to the frequency components of the Korotkoff sounds 11 are mixed into the signal detected by the Korotkoff sound sensor, these noises will be lost even though noise removal means are provided. There was a risk that the noise would be processed as a Korotkoff sound and the systolic blood pressure value and diastolic blood pressure value would be incorrectly determined.

First Means for Solving the Problems In order to solve the problems, the first invention provides a blood pressure measuring device comprising the cuff and the Korotkoff sound sensor,
A blood flow sound sensor that detects the blood flow sound generated from the artery is provided at a position upstream of the artery than the Korotkoff sound sensor of the cuff, and the blood flow sound sensor opens and closes in synchronization with the signal detected by the blood flow sound sensor. The present invention is characterized in that a gate means is provided for allowing the signal detected by the Korotkoff sound sensor to pass only during a certain period during which the Korotkoff sound is expected to occur.

Effect of the First Invention In the blood pressure measuring device configured as described above, the blood flow sound generated in accordance with the pulsation of the artery is detected by the blood flow sound sensor provided upstream of the artery than the Korotkoff sound sensor. The gate means is detected prior to the Korotkoff sound detected by the sound sensor and is opened only for a certain period during which the Korotkoff sound is scheduled to be generated in synchronization with the generation or disappearance of the blood flow sound represented by the detected signal. he,
The signal detected by the Korotkoff sound sensor is allowed to pass. Then, only the signals that have passed within the certain period of time are processed by a computer or the like, and based on this, the systolic blood pressure value and the diastolic blood pressure value are determined. Therefore, even if noise due to body movement etc. mixes into the signal output from the Korotkoff sound sensor, it will be reliably removed by the gate means, improving the measurement accuracy of blood pressure values and ensuring the reliability of the device. It will be done.

Second Means to Solve the Problem Furthermore, in order to solve the problem, a second invention detects pulse waves generated from an artery in a blood pressure measuring device equipped with the cuff and a Korotkoff sound sensor. A pulse wave sensor is provided, and by opening and closing in synchronization with the rise of the pulse wave represented by the signal detected by the pulse wave sensor, the Korotkoff sound is detected by the Korotkoff sound sensor only for a certain period during which the Korotkoff sound is expected to occur. The present invention is characterized in that a gate means is provided for allowing passage of the signal.

Effect of the Second Invention In the blood pressure measuring device configured as described above, the pulse wave sensor detects the pulse waves generated with the pulsation of the artery, and the pulse wave that precedes the Korotkoff sounds detected by the Korotkoff sound sensor is detected by the pulse wave sensor. The gate means is opened only for a certain period of time during which the Korotkoff sound is expected to occur in synchronization with the rise of the wave, allowing the signal detected by the Korotkoff sound sensor to pass through. Then, the systolic blood pressure value and the diastolic blood pressure value are determined based only on the signals that have passed within the certain period.

Note that although Korotkoff sounds occur in synchronization with the generation of pulse waves, the rise of the pulse waves is detected prior to the generation of Korotkoff sounds. It becomes possible to provide it at a certain position.

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

FIG. 1 is a block diagram showing an example of a blood pressure measuring device according to the first invention. In the figure, reference numeral 10 denotes a rubber bag-shaped cuff that is wrapped around the upper arm of the subject.
A pressure sensor 12.0 detects the pressure of the cuff lO. Electric pump 1 that supplies gas into the cuff 10 and increases its pressure
4 and an exhaust valve device 16 that exhausts gas within the cuff 10 to lower the pressure of the cuff 10. The exhaust valve device 16 is composed of, for example, an on-off valve for rapid evacuation, a throttle valve for slow evacuation, and an on-off valve. The cuff 10 can be switched between three states: a rate-limited evacuation state in which the gas in the cuff 10 is gradually ejected, and a rapid evacuation state in which the gas in the cuff 10 is rapidly ejected. The pressure sensor 12 also includes an amplifier, and after amplifying the detected pressure, supplies a pressure signal SP representing the pressure to the low-pass filter 18. The low-pass filter 18 removes vibration components such as pulse waves from the pressure signal SP, and
A cuff pressure signal SC representing a static pressure of 0 is supplied to the A/D converter 20.

The cuff 10 also has a portion located above the artery when it is wrapped around the upper arm, etc., and microphones 22 and 24 are disposed at the upstream and downstream ends of the cuff 10, respectively. .

Each of the microphones 22 and 24 detects the vibration sound generated by blood flow from the artery and outputs sound signals SSI and SS2 representing the vibration sound.The output sound signals SSI and SS2 are respectively After being amplified by amplifiers 26.28, the signals are supplied to bandpass filters 30.32. The bandpass filter 30 filters blood flow sound components (for example,
It extracts only the vibration component of about 150 Hz and removes the other vibration components, and together with the microphone 22 and the amplifier 26, it constitutes a blood flow sound sensor (
A blood flow sound signal SB representing blood flow sound is supplied to the A/D converter 20. Furthermore, the band-pass filter 32 filters a so-called Korotkoff sound component (for example, 10
The microphone 2
4 and an amplifier 28 constitute a Korotkoff sound sensor, and supply a sound signal SK representing the Korotkoff sound to the A/D converter 20.

The A/D converter 20 then converts the supplied cuff pressure signal SC, blood flow sound signal SB, and sound signal SK into digital codes to generate a cuff pressure signal SCD and a blood flow sound signal S, respectively.
After converting the sound signal to BD and SKD, it is supplied to the I10 port 34. I10 port 34 also has a push button PB.
A start signal SA is supplied from the start signal SA.

The I10 port 34 connects the CPU 36. which constitutes the microcomputer via the data bus line. It is connected to RAM38 and ROM40, and CPU36 is connected to RAM38 and ROM40.
The drive signal MP and the exhaust valve device 1 operate the electric pump 14 by processing the supplied signal according to the program stored in advance in the ROM 40 while utilizing the temporary storage function of the ROM 40.
6 to I10 port 3 respectively.
Output from 4. Further, a display signal DD is supplied to the display device 42 so that the systolic blood pressure value and the diastolic blood pressure value are displayed numerically. Note that the CPU 36 is supplied with a pulse signal CK of a predetermined frequency from a clock signal source 44.

Next, the operation of this embodiment will be explained based on the flowcharts of FIGS. 2 and 3 and the time charts t,'= of FIG. 4.

In FIG. 2, first, when a power switch (not shown) is turned on, an initialization step (not shown) is performed, and then step S1
is executed, and it is determined whether or not the push button 10PB has been operated, in other words, whether or not the activation signal SA is being supplied to the I10 boat 34. When the activation signal SA is supplied, step S2 is then executed, in which the exhaust valve device 16 is closed and the electric pump 14 is activated, and the actual pressure in the cuff 10 represented by the cuff pressure signal SCD is predetermined. The pressure is increased until the target pressure reaches or exceeds the target pressure, which is higher than the patient's systolic blood pressure value. When the pressure in the cuff 10 reaches the target pressure, the electric pump 14 is stopped, the exhaust valve device 16 is switched to the rate-limiting exhaust state, and the pressure in the cuff 10 is gradually lowered. During this process, a blood pressure value determination routine in step S3 is executed.

In the blood pressure value determination routine, the state of hemostasis in the artery is released by gradually relaxing the compression state by the cuff 10, and the cuff pressure signal SCD at the time when the Korotkoff sound was first detected is determined based on the K sound signal SKD. cuff 1
While the pressure of 0 is taken as the systolic blood pressure value, the pressure of the cuff 10 further decreases, the compression state by the cuff 10 is relaxed, and the cuff pressure signal SCD is obtained when the Korotkoff sound can no longer be detected based on the K sound signal SKD. The pressure in the cuff 10 represented by is determined as the diastolic blood pressure value. Blood pressure (if both the systolic blood pressure value and the diastolic blood pressure 1 positive value are determined in the value determination routine, then steps S4 and S5
is executed, the exhaust valve device 16 is switched to the rapid exhaust state, the gas in the cuff 10 is rapidly exhausted, and the systolic blood pressure value and the diastolic blood pressure value are numerically displayed on the display device 42.

On the other hand, in parallel with the blood pressure value determination routine in step S3, the interrupt routine shown in FIG. The sound signal SKD is allowed to pass through.

That is, first, in step R1, the blood flow sound signal S
It is determined whether blood flow sound is detected based on the BD,
If no blood flow sound is detected, step R1 is repeated, but if blood flow sound is detected, then step R2 is performed.
is executed. Time ti in FIG. 4 shows the state at this time. Note that at this time, the counting time T of the timer that counts the pulse signal CK supplied from the clock signal source 44 is reset.

In step R2, the time Tm1n from when the blood flow sound is detected until the gate is opened is calculated. This Tm1n
, calculates the time difference Δt n-1 between the previously detected blood flow sound and the Korotkoff sound, and schedules this time as the delay time from when the blood flow sound is detected this time until the Korotkoff sound is generated, It is calculated by subtracting a certain period of time (half of the gate opening time, for example, about 150 fflsec) from the time Δt n-1. In this case, the time difference between the previous blood flow sound and the Korotkoff sound cannot be calculated while the compression pressure of Cuffe 0 is high and the Korotkoff sound is not detected.
A predetermined setting value is used as Tm1n.

Subsequently, step R3 is executed, and the counting time T of the timer is
It is determined whether or not Tm1n has been reached. The execution of step R3 is repeated until the counting time T reaches Tm1n, but when the counting time T reaches Tm1n, step R4 is executed, the gate is opened, and the K sound signal S
Passage of KD is allowed.

Time t2 in FIG. 4 shows the state at this time.

Next, step R5 is executed, and it is determined based on the K sound signal SKD whether or not a Korotkoff sound has been detected. If the Korotkoff sound is detected, step R7 is subsequently executed, and the gate is closed to prevent the passage of the sound signal SKD. However, since the Korotkoff sound is usually not detected immediately after the gate is opened, Step R6 is executed and it is determined whether the timer count T has reached Tmax. This 7'max is the time difference Δt
71-1 plus a certain time (half of the gate opening time, for example, about 150 m5ec), and when the counting time T is Tmax or less, the above step R5 is performed.
The execution of R6 is repeated and the gate is opened.

Therefore, the gate that restricts the passage of the K-sound signal SKD is set around the time when the Korotkoff sound is expected to occur.
They are opened for a certain period of time (approximately 150 msec) each before and after, and Korotkoff sounds are usually detected during this period and used as sampling data for determining blood pressure values. Time t3 in FIG. 4 shows the state at this time. In addition, in the unlikely event that the Korotkoff sound cannot be detected, the counting time T of the timer is
At time t4 in FIG. 4, which exceeds max, the gate is closed. Note that the actual time difference Δtn between the current blood flow sound and the Korotkoff sound is defined as the delay time Δt n−+ from when the next blood flow sound is detected until the Korotkoff sound is generated in step R8, and the next gate It is used as a reference for calculating opening and closing times.

As described above, according to the blood pressure measuring device of the present embodiment, by executing the interrupt routine that constitutes the gate means, the sound signal SKD is allowed to pass only during a certain period during which the Korotkoff sound is expected to occur, and the sound signal SKD is allowed to pass during that period. Since the Korotkoff sounds detected based only on the sound signal SKD are used as sampling data for determining the blood pressure value, for example, as shown by the dashed line in Fig. Even if the noise N gets mixed into the sound signal SKD,
Since it is not signal-processed as a Korotkoff sound, there is no risk that the blood pressure value will be erroneously determined due to such noise N, and the reliability of the blood pressure measuring device is improved.

, 1 1 In addition, in this example, the time difference Δt n-1 between the previously detected blood flow sound and the Korotkoff sound is calculated, and this time is set as the time when the Korotkoff sound is expected to occur. Even if the time from when the blood flow sound is detected until the Korotkoff sound is generated varies due to individual differences in the blood flow or changes in the pressure of the cuff 10, the scheduled time for the Korotkoff sound to occur will be changed to follow the variation. This has the advantage that the period during which the gate is open can be shortened and measurement accuracy can be further improved.

Next, an embodiment corresponding to the second invention will be described.

In the following description, parts common to those in the embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 5, the cuff 10 is located on the artery when it is wrapped around the upper arm, and a microphone 50 is disposed at the downstream end of the cuff 10. The microphone 50 detects the vibration sound generated from the artery and outputs a sound signal SS3 representing the vibration sound.
It is capable of detecting not only audible sound but also vibrational sound with a lower frequency. For example, a displacement microphone, an acceleration microphone, etc. are preferably used. The output sound signal SS3 is amplified by an amplifier 52. After that, it is supplied to band-pass filters 54 and 56. The band-pass filter 54 extracts only the pulse wave component (for example, a vibration component of about 10 to 50 Hz) generated in conjunction with the pulsation of the artery from the sound signal SS3. The microphone 50 and the amplifier 52
Together, they form a pulse wave sensor and supply a pulse wave signal SM representing a pulse wave to the A/D converter 20. Furthermore, the bandpass filter 56 is the bandpass filter 3 in the embodiment described above.
Similarly, only the Korotkoff sound component generated as the cuff 10 is compressed is extracted from the sound signal SS3. Together with the microphone 50 and the amplifier 52, the Korotkoff sound sensor is configured, and the sound signal SK is used to represent the Korotkoff sound. is supplied to the A/D converter 20. Then, the pulse wave signal SM and the sound signal S supplied to the A/D converter 20 are
K is each digitally encoded pulse wave signal SMD
and after being converted into sound signal SKD, I10 port 3
4 is output.

The blood pressure measuring device configured in this way uses the K sound signal SKD.
except that the opening and closing of the gate that restricts passage of the second pulse wave signal SMD is performed in synchronization with the rise of the pulse wave represented by the pulse wave signal
It is operated according to the flow chart shown in FIG. That is, instead of determining whether blood flow sound has been detected in step R1, it is determined whether a pulse wave rising point has been detected.

When detecting the rising point of this pulse wave, for example, as disclosed in Utility Application No. 15595/1987, previously filed by the present applicant, a certain range is detected on the near side of the maximum inclination angle portion of the pulse wave. 45 to 85 in the waveform within that range.
It is sufficient to detect a portion of a preset inclination angle within a range of .degree. as a rising point.

In the blood pressure measuring device of this embodiment, in addition to obtaining the same effects as in the first embodiment, pulse waves and Korotkoff sounds are both detected by the 11-piece microphone 50. , there is an advantage that the device can be easily constructed.

Although the embodiments of the present invention have been described above based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the above embodiment, the opening/closing time Tm1n and Tmax of the gate that limits the passage of the sound signal SKD.

is determined by calculation from the previous time difference Δt n-+, but it is also possible to set it to a constant value in advance, taking into consideration individual differences among subjects. In this case, the set value may be corrected depending on the blood flow velocity of the artery or the pressure of the cuff 10.

Further, in the above embodiment, the gate means is incorporated into the microcomputer as an interrupt routine, but only during a certain period when the Korotkoff sound is scheduled to be generated in synchronization with the generation of blood flow noise or the detection of the rising point of the pulse wave. It is also possible to configure the gate means using hard logic, such as by providing a gate circuit that allows the sound signal SKD to pass between the bandpass filter 32 or 56 and the A/D converter 20.

Further, in the embodiment described above, the blood pressure value is measured during the step of lowering the blood pressure of the cuff 10, but the blood pressure value may be measured during the step of increasing the pressure of the cuff 10.

Furthermore, in the first embodiment, the gate is opened and closed in synchronization with the generation of blood flow sound, but the gate may be opened and closed in synchronization with the disappearance of blood flow sound.

Further, in the second embodiment, both the pulse wave and the Korotkoff sound are detected by one microphone 50, but a microphone for detecting the pulse wave may be provided separately from the microphone 50. Alternatively, the configuration may be such that the pulse wave is detected from the pressure vibration of the cuff 10 detected by the pressure sensor 12, or the pulse wave is detected from the vibration of the arterial surface wall using an ultrasonic interference needle. It is possible.

Although other examples are not given, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

Effects of the Invention As detailed above, according to the blood pressure measuring device of the present invention,
A gate means that opens and closes in synchronization with the rise of blood flow sounds or pulse waves allows the passage of signals detected by the Korotkoff sound sensor for a certain period during which Korotkoff sounds are expected to occur, and only the signals that have passed during that period are allowed to pass. Since the signal is processed as sampling data for determining the blood pressure value, noise caused by body movement etc. is reliably removed from the sampling data, improving the measurement accuracy of the blood pressure value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the configuration of a blood pressure measuring device that is an embodiment of the first invention. 2 and 3 are flowcharts illustrating the operation of the apparatus of FIG. 1. FIG. 4 is a time chart showing the opening and closing of the gate in accordance with the execution of the flowchart in FIG. 3, together with the occurrence of blood flow sounds and Korotkoff sounds. FIG. 5 is a block diagram illustrating the configuration of a blood pressure measuring device that is an embodiment of the second invention. 10: Cuff applicant Nippon Kolin Co., Ltd. Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) Equipped with a cuff for compressing a part of a living body and a Korotkoff sound sensor installed on the cuff to detect Korotkoff sounds, the blood pressure is determined based on the Korotkoff sounds generated from the arteries as a result of compression by the cuff. In the blood pressure measuring device for measuring blood pressure, a blood flow sound sensor for detecting blood flow sound generated from the artery is provided at a position upstream of the artery than the Korotkoff sound sensor of the cuff, and a blood flow sound sensor that detects blood flow sound generated from the artery is provided. A blood pressure measuring device comprising: a gate means that opens and closes in synchronization with the Korotkoff sound sensor to allow passage of the signal detected by the Korotkoff sound sensor only during a certain period during which the Korotkoff sound is expected to occur. (2) Equipped with a cuff for compressing a part of the living body and a Korotkoff sound sensor installed on the cuff to detect Korotkoff sounds, blood pressure is calculated based on the Korotkoff sounds generated from the arteries as a result of compression by the cuff. In a blood pressure measuring device for measuring blood pressure, a pulse wave sensor is provided to detect a pulse wave generated from the artery, and the pulse wave sensor is opened and closed in synchronization with the rise of the pulse wave represented by the signal detected by the pulse wave sensor. A blood pressure measuring device comprising a gate means for allowing the signal detected by the Korotkoff sound sensor to pass only during a certain period during which the Korotkoff sound is expected to occur.