JPH0158978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic blood pressure measuring device that automatically measures the blood pressure of a human body, and in particular, it is capable of allowing pressure changes in a manifold during periods when there is no noise that would interfere with blood pressure measurement, and when noises that interfere with blood pressure measurement are present. The present invention relates to an automatic blood pressure measuring device that prevents pressure changes.

An indirect (non-invasive) automatic blood pressure measuring device is equipped with a valve that compresses a part of the human body, and detects blood vessel sounds that occur as pressure changes in the valve or pulse waves that appear in pressure vibrations in the valve. Blood pressure measurements are made by automatically detecting changes. In such an automatic blood pressure measuring device, blood vessel sound signals output from the blood vessel sound sensor or output from the pressure sensor that detects the pressure in the manifold are detected when the person to be measured moves or when the measuring person touches the manchette. If noise mixes into the pressure signal being measured, erroneous measurements will occur. Therefore, the blood vessel sound signal or pressure signal required for measurement and the noise are determined based on the signal level and frequency. Erroneous measurements are prevented by blocking signal input for measurement. Here, the above-mentioned noise means a voltage and current component other than a regular signal that is mixed into a regular signal such as a blood vessel sound signal or a pressure signal.

However, according to such conventional automatic blood pressure measuring devices, if noise is continuously mixed in for a certain period of time, the pressure in the manifold is changed regardless of the presence or absence of noise, so it is difficult to determine when the noise occurred. There is a drawback that automatic blood pressure measurement is impossible because the systolic blood pressure measurement timing or the diastolic blood pressure measurement timing that occurs during the pressure change process of the manifold overlaps.

On the other hand, the pressure of the valve is changed in stages in advance, the presence or absence of noise is checked at each stage, and only when there is no noise, a blood vessel sound signal or a pulse wave signal, which is pressure vibration of the valve, is collected and the pressure is changed in the next stage. An automatic blood pressure measuring device has been proposed, but with such a device, the blood pressure measurement period becomes long and the person being measured is likely to fall into a state of stasis.
Because it differs from conventional continuous pressure changes, the medical evidence for blood pressure measurements is not necessarily sufficient.
There were some inconveniences that made it impractical.

The present invention has been made against the background of the above-mentioned circumstances, and its purpose is to allow pressure changes in the manifold during times when noise that would interfere with automatic blood pressure measurement does not exist, and to An object of the present invention is to provide an automatic blood pressure measuring device that prevents pressure changes in a patient.

In order to achieve such an object, the present invention includes a manifold that changes the compression state of a part of the human body by raising or lowering the pressure when measuring blood pressure, and which measures pressure based on pulse waves expressed as pressure vibrations of the manchette. An automatic blood pressure measuring device that measures blood pressure includes: (1) a pressure sensor that detects the pressure within the manifold and outputs a pressure signal representing the pressure; and (2) a pressure fluctuation that is different from the pulse wave in the pressure signal. a noise detection device that detects noise based on the presence of the noise and outputs an abnormal signal representing the presence of the noise; (3) supplying fluid to the manchet while the abnormal signal is output; Alternatively, a pressure stop means is provided to temporarily stop the rise or fall of the pressure in the manchette by stopping the discharge of the fluid previously supplied to the manchette, and allow the pressure change in the manchette at a time when the noise is not present. It is characterized in that it prevents the pressure change when it exists.

In this way, when blood pressure is automatically measured by detecting changes in the size of the pulse wave, which is pressure oscillations in the manifold, if the subject moves or the person taking the measurement touches the manifold, When the noise detection device detects that noise is mixed into the pressure signal due to reasons such as
This avoids the overlap between the timing of noise contamination and the timing of measuring the systolic or diastolic blood pressure values that occur during the pressure change process of the pump, making it possible to automatically measure blood pressure even if noise contamination occurs continuously for a certain period of time. be. Moreover, compared to conventional automatic blood pressure measurement in which the pressure of the manifold is changed in stages, the period of compression by the manchette increases only by the period when noise is mixed in, and the pressure of the manifold can be changed continuously. , the patient's pain hardly increases, and highly reliable blood pressure measurements can be obtained.

In another embodiment, a manchet is provided which changes the compression state of a part of the human body by raising or lowering the pressure when measuring blood pressure, and the manchet An automatic blood pressure measurement device that measures blood pressure includes: (1) a blood vessel sound sensor that detects blood vessel sounds in the compressed body part and outputs a blood vessel sound signal representing the blood vessel sounds; (2) a blood vessel sound sensor that detects blood vessel sounds in the compressed body part; (3) a noise detection device that detects noise based on the fact that a different sound is included in the blood vessel sound signal, and outputs an abnormal signal representing the presence of the noise; pressure stop means for temporarily stopping the pressure rise or fall of the manchette by stopping the supply of fluid supplied to the manchette or the discharge of the fluid previously supplied to the manchette, and the noise is not present. The present invention is characterized in that the pressure change in the manifold is allowed during certain periods, and the pressure change is blocked during existing periods.

In this way, when automatically measuring blood pressure by detecting the occurrence and disappearance of Korotkoff sounds included in blood vessel sounds, it is possible to prevent the patient from moving or other equipment such as an electric scalpel operating. Due to etc.
When the noise detection device detects that noise is mixed in the blood vessel sound signal, the pressure stop means prevents the pressure change in the manifold within the detection period, so that the same effect as the above-described invention is obtained. is obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the drawings.

In FIG. 1, a pressure sensor 12, an air pump 14, and electromagnetic valves 16 and 18 are connected via conduits 20 to a rubber bag-shaped condom 10 that is wrapped around a part of the human body.

The pressure sensor 12 detects the pressure inside the apartment 10 and supplies a pressure signal SP representing the pressure to the pulse wave sensor 22 and A/D converter 24, and the pressure signal SP includes the pulse wave of the subject. is included as a vibration (alternating current) component. The pulse wave sensor 22 includes a filter that passes a signal in the frequency band of the pulse wave and an A/D converter that converts the magnitude of the passed signal into a code signal. A pulse wave signal SM representing the pulse rate is supplied to the I/O port 26. A/D
The converter 24 converts the pressure signal SP representing the pressure in the manifold 10 into a code signal and supplies the signal to the I/O port 26 as the manifold pressure signal SK.

The air pump 14 includes a drive motor,
Pump drive signal supplied from I/O port 26
Air is supplied into the passenger compartment 10 according to SA. The solenoid valve 16 is an on-off valve equipped with a port connected to the pipe line 20 and an atmospheric port 28 opened to the atmosphere, and is configured to close the pipe line according to the rapid exhaust signal SH supplied from the I/O port 26. 20 to the atmosphere. And solenoid valve 1
8 is an on-off valve inserted between the pipe line 20 and the throttle valve 30, and the pipe line 20 and the throttle valve are closed according to the exhaust stop signal SL, which is an abnormal signal supplied from the I/O port 26. 30, and constitutes a pressure stop means that prevents a pressure drop within the passenger compartment 10 when noise occurs.

The I/O port 26 is connected via the data bus line.
CPU (processing unit) 32, RAM 34 and
It is connected to the ROM 36, and the signals supplied to the I/O port 26 according to commands from the CPU 32 are supplied to the data bus line, and the signals supplied from the data bus line are transmitted to the pump 14 and the solenoid valve 1.
6, 18. The CPU 32 has ROM 36 in advance.
Execute signal processing using the temporary storage function of RAM 34 according to the program stored in the I/
A pump drive signal SA, a rapid exhaust signal SH, and an exhaust stop signal SL are outputted through the O port 26.
Therefore, CPU32, RAM34, ROM36
It is also a noise detection device that detects noise and outputs an abnormal signal.

A start switch 38 is provided that generates a start signal SS in response to a pressing operation to start blood pressure measurement, and the start signal SS is supplied to the I/O port 26. Further, a blood pressure display 40 is provided which numerically displays the blood pressure value automatically measured in accordance with the display signal SB output from the I/O port 26.

The operation of this embodiment will be explained below.

When a power switch (not shown) is turned on, power is supplied to each part of the apparatus, and the CPU 32 operates according to the flowchart of FIG. 2 showing a program stored in advance in the ROM.

First, step S1 is executed, and the operating state of the start switch 38 is determined. As long as the start switch 38 is not pressed and the start signal SS is not generated, execution of step S1 is repeated.
When the start signal SS is supplied to the I/O port 26 by the pressing operation, the next steps S2 and S3 are started.
is executed. That is, in step S2, the pump drive signal SA is supplied to the air pump 14, air is supplied from the air pump 14 into the apartment 10, and the pressure inside the apartment 10 starts to rise, and at the same time, in step S3, the air pump 14 is supplied with air. It is determined whether the operating time T _p exceeds a predetermined constant operating time T1. Here, the certain operating time T1 is the time required for the pressure in the pump 10 to reach the set pressure under normal conditions in order to determine a failure in the booster system such as damage to the pipe line 20 or the pump 10 or a failure in the air pump 14. It is set larger than , and is usually set in advance to about 30 seconds. If the operating time T of the air pump 14 exceeds a predetermined constant operating time T1, step S14, which will be described later, is executed to rapidly exhaust the air pump 10, but if it does not exceed the predetermined operating time T1, step S4 is executed. Running manchet pressure signal
It is determined whether or not the pressure P in the apartment 10, represented by SK, has reached a predetermined constant pressure P1. Here, the constant pressure P1 is set to a value that is sufficiently larger than the systolic blood pressure value of the subject. The pressure P of the pump 10 is its set pressure.
If P1 is not exceeded, step S3 is executed again, but if it is exceeded, steps S5 to S7 are executed. In step S5, as shown at time A in FIG. 3, the supply of the pump drive signal SA to the air pump 14 is stopped and the air pump 14 is
0 pressure rise is stopped and the step
At S6, the output of the exhaust stop signal SL from the I/O port 26 is blocked, the solenoid valve 18 is kept open, the air in the manifold 10 is exhausted through the throttle valve 30, and the pressure drop in the manifold 10 is reduced. Begins. Then, in step S7, it is determined whether the blood pressure measurement has been completed, that is, whether the measurement of the diastolic blood pressure value has been completed. That is,
As shown in FIG. 4, which shows an enlarged view of the alternating current component contained in the pressure signal SP, the magnitude of the pulse wave has a property of increasing and decreasing as the pressure of the manifold 10 decreases, and the magnitude of the pulse wave is pre-stored in the ROM 36. According to a blood pressure measurement program (not shown), for example, the pressure value of the manchette 10 represented by the manchette pressure signal SK at time B when the magnitude of the pulse wave represented by the pulse wave signal SM suddenly increases is set as the systolic blood pressure, and the magnitude of the pulse wave is determined as the systolic blood pressure. Mansion 1 at point C when it suddenly decreased
Blood pressure is measured using a pressure value of 0 as the diastolic blood pressure. Then, a determination is made in step S7 based on the presence or absence of a signal indicating that the measurement of the diastolic blood pressure value has been completed, and a display signal indicating the blood pressure measurement value.
SB is output to the blood pressure display 40, and the measured values of the systolic and diastolic blood pressure values are displayed. Note that the waveforms in FIG. 4 are for ease of understanding and do not represent actual pulse waves.

When the measurement of the diastolic blood pressure value is completed, step S14 is executed and the rapid exhaust signal SH is supplied to the solenoid valve 16, so that the air in the manifold 10 is discharged from the pipe 2.
0 and to the atmosphere through the solenoid valve 16, and the pressure inside the passenger compartment 10 begins to be exhausted rapidly. Point C in FIG. 3 shows this state. However, if the measurement of the diastolic blood pressure value has not yet been completed,
Steps from step S8 onwards are executed.

First, in step S8, based on the pulse wave signal SM and the valve pressure signal SK, the pressure value P of the valve 10 at that time is determined every time a pulse wave occurs.
is read (stored), and in step S9 it is determined whether the pressure value P stored this time is larger than the minimum pressure value Pmin stored before the previous time plus a constant value α. Ru. In other words, the amount of variation (P-Pmin) in the direction of pressure increase, which is the opposite direction to the direction of steady decrease in the pressure of the manchette 10, due to the movement of the person to be measured or the touch of the manchette 10 by the measuring person or the doctor undergoing surgery. If it exceeds the value α, it is determined to be noise. The value α is set slightly larger than the maximum value of the pulse wave size so that the alternating current component due to a normal pulse wave is not judged as noise, and is usually 3 to 10 mm.
A value around Hg is suitable. In addition, if the pressure value P of the manifold 10 is read for the first time in step S8 after the start of evacuation in step S6, that is, the previous minimum pressure value
If Pmin is zero, the determination at step S9 is not made.

If the amount of variation in the pressure increasing direction of the pump 10 does not exceed the value α, steps S7 to S9 are executed again, but if the amount of variation exceeds the value α and is determined to be noise, step S9 is executed. is executed, the exhaust stop signal SL is output, and the solenoid valve 18
is closed, stopping the pressure drop in the manifold 10. Time D in FIG. 3 shows this state. Then, in step S11, it is determined whether the exhaust stop time _Ts of the passenger compartment 10 exceeds a predetermined maximum stop time T2. That is,
This is determined in order to protect the person being measured from being left in a state of stasis due to some reason, and is preset at an optimal time depending on the person being measured. If the exhaust stop time _Ts exceeds the maximum stop time T2, step S14 is executed and the pressure in the manifold 10 is rapidly lowered, but if the exhaust stop time _Ts does not exceed the maximum stop time T2, step S14 is executed. , the next step S12 is executed, and it is determined whether at least two normal pulse waves have occurred consecutively. In other words, the magnitude of the preceding pulse wave signal SM is compared with the magnitude of the current wave signal SM, and if the rate of change in these magnitudes is within a certain range, it is determined that normal pulse waves are continuous. It is something that

If normal pulse waves have not yet occurred continuously, step S11 is executed again, but if they have occurred continuously, step S13 is executed, the output of the exhaust stop time SL is again blocked, and the pump 1
Zero pressure drop is resumed. Time E in FIG. 3 shows this state.

In this way, according to the present embodiment, the pressure drop in the manifold 10 is prevented during the period when noise that causes erroneous measurements is mixed in, so that the maximum pressure drop that occurs in the timing of noise incorporation and the process of pressure drop in the manifold is controlled. This avoids overlap with the measurement timing of high blood pressure values or diastolic blood pressure values, and enables automatic blood pressure measurement even if noise continues for a certain period of time. Therefore,
Since remeasurements due to noise are eliminated, this is particularly effective in automatic measurement over a long period of time to measure trends in blood pressure values. Moreover, compared to the conventional automatic blood pressure measurement that changes the pressure in the manifold in stages, the compression period of the manifold 10 only increases by the period when noise is mixed in, and the pressure in the manifold 10 is continuously lowered. As a result, the patient's pain hardly increases and highly reliable blood pressure measurements can be obtained.

Next, another embodiment of the present invention will be described.

In steps S8 and S9 in the above embodiment, noise is determined when the amount of change in the pressure increasing direction of the manifold 10 is larger than a predetermined value α; ) may be determined to be noise when it exceeds a predetermined constant value β. For example, as shown in Figure 5,
At step S8', the pressure P of the manifold 10 is read at fixed time intervals △T, and then
At S9', the previous pressure value P _o of manchet 10
It is determined whether the pressure difference △P between the current pressure value P _o+1 , that is, the amount of change (change speed) per time △T is larger than a predetermined value β, and if it is larger, the step Step S10 is executed, and if it is smaller, step S7 is executed.

According to this embodiment, there is an advantage that even if the amount of change in the pressure increase direction of the passenger compartment 10 does not reach the value α, high frequency noise can be detected, and noise that changes in the pressure decrease direction can also be detected. .

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, in the flowchart of FIG. 2, steps S8' and S9' of the other embodiments described above may be inserted between steps S9 and S10.
In such a case, noise can be determined from the rate of pressure change in the manifold 10 and the amount of pressure change in the pressure increasing direction, so there is an advantage that a more reliable blood pressure measurement value can be obtained. As a method for detecting such noise, it is determined that it is noise when the magnitude of the pulse wave signal SM is larger than a predetermined constant value or when the rate of change in the magnitude of the pulse wave signal SM exceeds a constant rate of change. You can also use the manchet pressure signal
The vibration waveform pattern included in the SK may be recognized by means such as integration, and if a vibration waveform other than the pulse wave pattern is recognized, it may be determined to be noise. In addition, the pressure reading in step S8 may be carried out for a short period of time (4 m) as necessary.
There is no problem even if the process is performed periodically (on the order of seconds).

Between steps S12 and S13 in the above embodiment,
A step may be inserted to raise the pressure again by a predetermined constant pressure before restarting the exhaust. In such a case, in order to avoid the noise generated due to the operation of the solenoid valve 18 to restart the exhaust, the pulse wave signal input when the solenoid valve 18 is activated is
Even if SM is canceled, the pressure value of the manifold 10 at the time of cancellation does not overlap with the pressure value of the manifold 10 whose pressure change was prevented in step S10, and a dead zone where blood pressure measurement is impossible is created within the blood pressure measurement range. This has the advantage of eliminating the problem that occurs.

The A/D converter 24 is driven in a time-division manner, and at certain times the pulse wave is converted into a code signal and the pulse wave signal SM is generated.
can be output. In such a case, an A/D converter within the pulse wave sensor 22 is not required, which has the advantage that the device is inexpensive.

In the above-mentioned embodiment, the blood pressure measurement is performed in the process of decreasing the pressure of the manifold 10, but the blood pressure measurement is performed in the process of increasing the pressure of the manifold 10, and when noise occurs during the blood pressure measurement, the blood pressure measurement is performed in the process of decreasing the pressure of the manifold 10. There is no problem even if the structure is such that the pressure rise in the pressure is prevented. In such a case, there is no need to increase the pressure in the manifold 10 above the systolic blood pressure value, which has the advantage of shortening the blood pressure measurement time and reducing pressure on the subject.

In the embodiments described above, the noise detection device includes:
It is composed of a CPU 32, a RAM 34, and a ROM 36.
Equipped with a comparator that determines whether the magnitude of the pulse wave included in the pressure signal SP that represents the pressure of It can be configured even if it is twisted.

In the embodiment described above, the pressure stop means is constituted by a solenoid valve 18 that prevents exhaustion.
In an apparatus that measures blood pressure when the pressure in the manifold 10 increases, driving power is supplied to the air pump 14 or a solenoid valve inserted between the air pump 14 and the conduit 20 to block the supply of air to the manifold 10. It consists of steps to prevent

In addition, the blood pressure measurement in the above-mentioned embodiment is performed at a point in time when the magnitude of the pulse wave, which is a vibration component included in the pressure signal SP, suddenly changes. The present invention is also applicable to a well-known automatic blood pressure monitor that is configured to measure the systolic blood pressure and diastolic blood pressure values based on the pressure value of the mantisfactory 10 at the same time. In such a case, instead of the pulse wave sensor 22 shown in FIG. 1, a blood vessel sound sensor such as a microphone that detects blood vessel sounds in a compressed body part and outputs a blood vessel sound signal representing the blood vessel sounds may be used. and a detection device such as a bandpass filter that discriminates and detects the pulse sound, Korotkoff sound, and noise included in the blood vessel sound signal, and detects the pulse sound representing the pulse sound, the Korotkoff sound signal representing the Korotkoff sound, and the noise representing the noise. The signals are configured to be provided to each I/O port 26 and operate according to a flowchart similar to that shown in FIG. Note that the noise occurs when the sound included in the blood vessel sound signal has a frequency different from the frequency band of the pulse sound and Korotkoff sound, and/or when the sound included in the blood vessel sound signal has a sound in the frequency band of the Korotkoff sound. is configured to be detected when the
S8 and S9 are slightly different. That is, steps S8 and S9 are executed when a noise signal is output from the noise detection device, and step S10 is executed.
When no output is generated, step S7 is changed to a step that is executed.

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.

As described in detail above, according to the automatic blood pressure measuring device of the present invention, pressure changes in the manifold are prevented during automatic blood pressure measurement during a period in which noise that would interfere with blood pressure measurement is mixed in, so that noise can be reduced. This avoids the overlap between the time of contamination and the time of measuring the systolic blood pressure value or diastolic blood pressure value that occurs during the process of pressure change in the manifold, and automatic blood pressure measurement becomes possible even if noise contamination continues for a certain period of time. Moreover, compared to conventional automatic blood pressure measurement in which the pressure of the manifold is changed in stages, the compression period by the manchette is only increased by the period of noise, and the pressure of the manifold can be changed continuously. The patient's pain hardly increases, and highly reliable blood pressure measurements can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the configuration of an embodiment of the present invention. FIG. 2 is a flowchart illustrating the operation of the embodiment shown in FIG. 3 and 4 are graphs illustrating the operation of the embodiment of FIG. 1.
FIG. 5 is a partial flowchart showing another embodiment of the invention. 10:Mansion, 12:Pressure sensor, 1
8: Solenoid valve (pressure stop means), {32: CPU, 3
4: RAM, 36: ROM} (noise detection means).

Claims (1)

[Scope of Claims] 1. An automatic blood pressure system that includes a manifold that changes the compression state of a part of the human body by raising or lowering the pressure during blood pressure measurement, and that measures blood pressure based on pulse waves that appear as pressure vibrations of the manchette. The measuring device includes: a pressure sensor that detects the pressure inside the apartment and outputs a pressure signal representing the pressure; and detects noise based on the fact that the pressure signal includes pressure fluctuations different from the pulse wave; a noise detection device that outputs an abnormal signal indicating the presence of the noise, and stopping the supply of fluid supplied to the manifold or the discharge of the fluid previously supplied to the manifold while the abnormal signal is being outputted; Accordingly, a pressure stop means is provided for temporarily stopping the rise or fall of the pressure in the manchette, so that the pressure change in the manchette is allowed when the noise is not present, and the pressure change is blocked when the noise is present. An automatic blood pressure measuring device characterized by: 2. The noise detection device outputs the abnormality signal when the amount of pressure change in the direction opposite to the pressure change direction of the manifold exceeds a predetermined constant value. automatic blood pressure measuring device. 3. The automatic noise detection device according to claim 1, wherein the noise detection device outputs the abnormality signal when the amount of pressure change in the manchet over a certain period of time exceeds a predetermined certain value. Blood pressure measuring device. 4. An automatic blood pressure measuring device that is equipped with a manifold that changes the compression state of a part of the human body by raising or lowering the pressure during blood pressure measurement, and that measures blood pressure based on Korotkoff sounds included in blood vessel sounds generated from a compressed human body. , detecting blood vessel sounds in the compressed part of the human body;
a vascular sound sensor that outputs a vascular sound signal representing the vascular sound; and a vascular sound sensor that detects noise based on the fact that a sound different from the Korotkoff sound is included in the vascular sound signal, and outputs an abnormal signal representing the presence of the noise. and a noise detection device that prevents a pressure increase or increase in the manifold by stopping the supply of fluid supplied to the manchette or the discharge of the fluid previously supplied to the manchette while the abnormal signal is being output. An automatic blood pressure measurement system characterized in that a pressure stop means for temporarily stopping the lowering is provided, and the pressure change in the manchette is allowed when the noise is not present, and the pressure change is blocked when the noise is present. Device. 5. The noise detection device detects the Korotkoff sound when the sound included in the blood vessel sound signal has a frequency different from the frequency band of the Korotkoff sound and the pulse sound, and/or when the pulse sound is not generated. 5. The automatic blood pressure measuring device according to claim 4, wherein the abnormal signal is output when the abnormal signal is a sound having a frequency in a frequency band.