JPS61119240A - Continuous blood pressure measuring method - 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 improvements in methods for continuously measuring blood pressure.

Prior Art and Problems When measuring the blood pressure of a living body, a part of the living body is compressed with a cuff, and the blood pressure is measured based on the generation and disappearance of Korotkoff sounds or changes in pulse waves that occur during the process of gradually relaxing the pressure from the cuff. It is common to measure the value. However, according to such a conventional blood pressure measurement method, prior to blood pressure measurement, the cuff must be pressurized to a pressure value that is sufficiently larger than the blood pressure value to be measured, resulting in a long pressurization time. Further, after blood pressure measurement, the pressure inside the cuff is rapidly evacuated until it becomes equal to atmospheric pressure. Therefore, when monitoring trends in blood pressure values by continuously measuring the blood pressure value of a living body by repeating such pressurization and exhaustion, the measurement period becomes long and the number of measurement points per unit time becomes insufficient. Therefore, it was not possible to accurately grasp rapid changes in the blood pressure value of the living body.

Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is (1) gradually increasing the pressure of the cuff and measuring the blood pressure value during this pressure increase. Pressure increase process to be measured, (2
) After the blood pressure value is obtained, the cuff is rapidly evacuated and the blood pressure is lowered to a predetermined value lower than the blood pressure value and higher than atmospheric pressure.

In this manner, the blood pressure value is measured in the step of increasing the pressure of the cuff, and after the blood pressure value is obtained, the cuff is rapidly evacuated, so there is no need to increase the cuff pressure above the blood pressure value. In addition, in the rapid blood pressure lowering step, the cuff pressure is lowered to a predetermined value that is lower than the blood pressure value obtained during pressurization and higher than atmospheric pressure.1, the evacuation time is shorter than when the cuff is evacuated to atmospheric pressure. At the same time, for the next boosting process,
Since the pressure can be increased from a predetermined value higher than atmospheric pressure, the time required to increase the pressure of the cuff is significantly shortened.

Therefore, blood pressure values are measured very efficiently and continuously.

Other means for solving the problems and other aspects of the present invention are summarized as (1)
a pressurization step of gradually increasing the pressure of the cuff and measuring blood pressure during this pressurization; (2) the pressure of the cuff being higher than the blood pressure value obtained during the pressurization step by a predetermined constant value; gradually evacuating the cuff after reaching
(3) during the blood pressure lowering step, the pressure in the cuff is lower by a predetermined value than the blood pressure value obtained during the blood pressure lowering step; The method further includes the step of starting the step of increasing the pressure after reaching the value.

In this way, the blood pressure values are measured during the pressure increasing step and the blood pressure lowering step, and the blood pressure increasing step and the blood pressure lowering step are related to the blood pressure values obtained in the previous steps. Since the cuff pressure is started from a predetermined value determined by are significantly shortened. In addition, blood pressure values can be obtained extremely efficiently and continuously.

EXAMPLE Hereinafter, a detailed description will be given based on drawings showing an example of an apparatus to which the present invention is applied.

In FIG. 1, an air pump 10 as a pressure source is connected to a first tank 14 via a check valve 12.
Compressed air is stored in the tank 14. Note that, between the air pump 10 and the check valve 12, there is an unloading electromagnetic on-off valve 38 that reduces the start-up load of the air pump 10 by setting its output side to atmospheric pressure prior to operation of the air pump 10. is provided. The first kunk 14 includes a first electromagnetic on-off valve 16 and a noise blocking diaphragm device 1.
8. Connected to the cuff 24 via a main conduit 22 equipped with a first electromagnetic switching valve 20 in series, and connected to the first tank 1
4 and the main pipe line 22 is a sub pipe line 36 equipped with a second electromagnetic on-off valve 26, a noise prevention throttling device 28, a second tank 30, a second electromagnetic switching valve 32, and a third electromagnetic on-off valve 34. It is provided in parallel with the throttle device 18 and the first electromagnetic on-off valve 16. The expansion device 18 controls the air flow at a critical speed (
speed of sound), and prevents noise (pressure fluctuations) on the upstream side from being transmitted to the cuff 24 side. Further, the first electromagnetic switching valve 20 can be selectively switched between a communication state in which the first tank 14 or the second tank 30 and the cuff 24 are communicated, and an exhaust state in which the cuff 24 is communicated with the atmosphere.

The second electromagnetic switching valve 32 can be selectively switched between a communication state in which the second tank 30 and the cuff 24 are communicated, and an exhaust state in which the second tank 30 is communicated with the atmosphere through a throttle valve 39. .

The cuff 24 is a bag-like item made of a flexible sheet such as a rubber sheet or a vinyl chloride sheet, and is adapted to be wrapped around a part of a living body, such as the upper arm of a human body or a finger. In this embodiment, the width dimension is 2. It is a finger cuff of about CI1+ or 5 COI.

A first pressure sensor 40 is provided in the main conduit 22 between the cuff 24 and the first electromagnetic on-off valve 20 to detect the pressure inside the cuff 24 and output a pressure signal SPK representing the pressure. The pressure signal SPK is supplied to a pressure detection circuit 42 and a pulse wave detection circuit 44, respectively. The pressure detection circuit 42 is equipped with a low-pass filter, and the pressure signal SP
The static pressure of the cuff 24 is extracted by removing the vibration component contained in K, and a cuff pressure signal KP representing the pressure of the cuff 24 is supplied to the A/D converter 46. In addition, the pulse wave detection circuit 44
is equipped with a bandpass filter that passes pulse waves (pressure vibrations) generated in synchronization with the pulse of the living body, extracts the pulse waves included in the pressure signal SPK, and generates a pulse wave signal S representing the pulse waves.
M is supplied to the A/D converter 46. Further, a second pressure sensor 48 is provided in the second tank 30, and a pressure signal SPT representing the pressure inside the second tank 30 is supplied from the second pressure sensor 48 to the A/D converter 50. be done.

The controller 52 includes CPUs 54 . ROM56. RAM58. Output Portro 0. Equipped with an A/D converter 46°50, C
The PU 54 receives the input signal S while utilizing the temporary storage function of the RAM 58 according to a program stored in advance in the ROM 56.
P.T., K.P.

Processing the SM, the first electromagnetic on-off valve 16. Second electromagnetic on-off valve 2
6. Third electromagnetic on-off valve 34. Drive signals SDI, 502. to the first electromagnetic switching valve 20 and the second electromagnetic switching valve 32, respectively. SD
3. SK1. SK2 and a pump drive signal SDP to the pump drive circuit 62 to cause the pump drive circuit 62 to supply drive power to the air pump 10. Further, the CPU 54 sends the drive signal SDA to the unloading electromagnetic on-off valve 38 for a certain period of time prior to outputting the pump drive signal SDP.
and open it.

The operation of this embodiment will be explained below using the flowchart shown in FIG.

First, when a power switch (not shown) is turned on, initialization processing in step S1 is executed. In this initialization process, the release pump 10 is operated for a predetermined period of time to make the pressure in the first tank 14 higher than the critical pressure, and the pressure in the first tank 14 is, for example, 70 (ln
It is considered to be around Hg. The critical pressure is the pressure required to bring the air flow velocity to the critical velocity in the expansion device 18. Point A in Figure 4 shows this power-on state,
Further, prior to the operation of the air pump 10, the electromagnetic on-off valve 38 is opened for a certain period of time, for example, about 0.5 seconds to 1 second. This electromagnetic on-off valve 38 is always opened for a certain period of time as the air pump 10 operates, thereby reducing the start-up load on the air pump 10. Further, at the same time as the power is turned on, the second electromagnetic switching valve 32 is brought into communication, and the second electromagnetic switching valve 26 is opened to increase the pressure in the second tank 30 to a predetermined value. There is. That is, the interrupt routine shown in FIG. 3 is repeatedly executed at regular intervals, and when step SW1 is executed, the target value PL of the second tank 30 is calculated. The target value PL is the diastolic blood pressure value minus a certain value, for example 40 wHg. In the first cycle, since there is no blood pressure value, a predetermined general value, for example 40 mHg, is used. When step SW2 is executed, it is determined whether the actual pressure P2 of the second tank 30 has become larger than the target value PL, and if it has become larger, step SW3 is executed and the second electromagnetic switching valve 3 is
2 is switched to the discharge state, the second electromagnetic on-off valve 26 is closed, and the compressed air in the second tank 30 is discharged and its pressure is reduced. However, if the actual pressure P2 in the second tank 30 is not greater than the target value PL in step SW2, step SW4 is executed and exhaustion by the second electromagnetic switching valve 32 is stopped. After the blood pressure measurement starts, the pressure P2 in the second tank 30 tends to increase, so the pressure supply to the second tank 34 by the second electromagnetic on-off valve 26 is executed only in step s1.

Returning to FIG. 2, when step S2 is executed, it is determined whether or not an operation to start blood pressure measurement has been performed, in other words, whether or not the measurement start push button 64 has been operated. If it is not operated, step s2 is repeated, but if it is operated, step S3 is executed, the first electromagnetic on-off valve 16 is released, and the pressure increase of the cuff 24 is started. Fourth
Time B in the figure shows this state. At the time of starting this measurement, the first cuff, which had previously connected cuffs 2 and 4 to the atmosphere,
The electromagnetic switching valve 20 is switched to a communication state that connects the cuff 24 and the first tank 14, and the air pump 1
0 is operated for a certain period of time, for example, about 3 seconds. The operating time of the air pump 10 is to replenish the amount of air consumed to raise the pressure of the cuff 24 once, and to maintain the inside of the first tank 14 above the critical pressure. The air in the first tank 14 is supplied to the first electromagnetic on-off valve 16. Squeezing device 18. It is supplied into the cuff 24 through the first electromagnetic switching valve 20, and the pressure of the cuff 24 is gradually increased. This is the pressure increasing process.

In such a pressure increasing step, a blood pressure measurement routine in step S4 and step S5 are executed. In the blood pressure measurement routine of step S4, the pulse wave obtained during the pressurization period is read, and one of the diastolic blood pressure, systolic blood pressure, and mean blood pressure of the living body is measured based on the change in the pulse wave. It is determined whether the measurement is completed or not.

In addition, in the blood pressure measurement routine of step S4, a plurality of systolic blood pressure, diastolic blood pressure, and mean blood pressure may be measured.

When blood pressure measurement is completed in this way, step S6 is executed, the first electromagnetic on-off valve 16 is closed 1°, the third electromagnetic on-off valve 34 is opened, and the cuff 2 is closed.
4 is placed in communication with the second tank 30. Therefore, the pressure inside the cuff 24 is rapidly lowered until it becomes approximately equal to the pressure P2 inside the second tank 30. This is a rapid blood pressure lowering step of the cuff 24, and the 0 point in FIG. 4 indicates this state. As mentioned above, the pressure in the second tank 30 is maintained at about its target pressure (lower limit pressure) PL by the interrupt routine, so the pressure in the cuff 24 is, for example, 40° below the measured value.
The value is calculated by subtracting about n+Hg. The capacity of the second tank 30 is set to be sufficiently larger than that of the cuff 24. Then, step S7 is executed to determine whether or not to end the continuous measurement of blood pressure, in other words, the measurement end push button 66
It is determined whether or not has been operated, and if not operated, the steps from step 83 onward are repeatedly executed. As a result, the cuff pressure is changed in a sawtooth pattern as shown in FIG. 5, and the blood pressure value is continuously and efficiently repeatedly measured. Points T1 and T1 in FIG. 5 indicate blood pressure measurement points.

When it is determined in step S7 that the continuous measurement has ended, the termination process in step S8 is executed, the first electromagnetic switching valve 16 and the third electromagnetic switching valve 34 are closed, and the first electromagnetic switching valve 20 is placed in the exhaust state. can be switched to.

Therefore, the pressure inside the cuff 24 is rapidly discharged to the atmosphere through the first electromagnetic switching valve 20, and the pressure caused by the cuff 24 is released.

Point D in FIG. 4 shows this state.

As described above, according to this embodiment, blood pressure measurement is performed during the step of increasing the pressure of the cuff 24, and as soon as the blood pressure measurement value is obtained, rapid blood pressure reduction of the cuff is performed. In addition, since the rapid pressure drop of the cuff is a predetermined value that is smaller than the measured value by a predetermined value, that is, a value that is higher than atmospheric pressure and smaller than the measured value, the blood pressure reduction time of the cuff 24 and the next The time for increasing the pressure of the cuff 24 is shortened. As a result, the blood pressure value of the living body can be measured continuously and quickly, and detailed blood pressure monitoring can be realized.

Next, a device to which another aspect of the present invention is applied will be described. In the following description, the same parts as in the above-mentioned embodiments are given the same reference numerals and the description thereof will be omitted.

The device shown in FIG. 6 is constructed in substantially the same manner as the device shown in FIG. They differ in that they are This throttle valve 70 is used to gradually lower the pressure inside the cuff 24 when the pressure inside the second tank 30 is lowered to the pressure P2.

The operation of the apparatus shown in FIG. 6 will be described below with reference to the flowchart shown in FIG. Incidentally, after the power is turned on to the apparatus, the interrupt routine shown in FIG. 3 is periodically repeated as in the previous embodiment. In FIG. 7, the cuff 24 is pressurized by executing steps S31 to SS5, which are similar to steps S1 to S5 in the flowchart of FIG. 2, and the blood pressure is measured in this pressurization step. Then, step SS6 is executed to calculate the upper limit value P of the cuff pressure. For example, here is this. Next, in step SS7, the actual pressure P in the cuff 24 is
It is determined whether or not is larger than the upper limit value Pal, and if it is not larger, step S37 is repeatedly executed, but when it is larger, step SS8 is executed and the first electromagnetic on-off valve 16 is closed. The third electromagnetic on-off valve 34 is opened and pressure reduction of the cuff 24 is started. This is the pressure lowering process. Time point C in FIG. 8 shows this state.

During such a cuff pressure lowering step, the step S3
Steps SS9 and 5SIO similar to 4 and SS5
is executed, the blood pressure value is measured, and it is determined whether the measurement is complete. When the blood pressure measurement is completed in this way, step 5S11 is executed to calculate the lower limit value PL of the cuff pressure, which is the subtracted value. The second tank 30 is controlled to have a pressure equal to this lower limit value PL by the interrupt routine (FIG. 3). Then, step 5812 is executed to determine whether the measurement has ended, in other words, whether the measurement end push button 66 has been operated. Step 5
If it is determined in S12 that the measurement is not completed,
As shown at time E in FIG. 8, steps SS3 and subsequent steps are executed again to start increasing the pressure of the cuff, and during this pressure increasing step, the blood pressure is measured again. By repeatedly performing the above steps, blood pressure values can be measured continuously and efficiently. FIG. 9 shows changes in cuff pressure that repeatedly rise and fall as a result of execution of such steps, and T1 to T6 show measurement points measured during such rise and fall.

If it is determined in step SS2 that the measurement has ended, step S12 is executed again and the process is kept on standby until the measurement start push port 64 is operated again.

As described above, according to the present embodiment, blood pressure values are determined in the pressure increasing step and the blood pressure lowering step of the cuff 24, and the pressure increasing start point and the blood pressure decreasing start point are respectively constant values relative to the measured values. Since the value is determined at a large value or a fixed value at a small value, blood pressure measurements can be repeated extremely quickly, allowing detailed blood pressure monitoring.

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, step 34. above. SS4. In the blood pressure measurement routine in SS9, the blood pressure value is determined based on changes in the pulse wave. For example, the blood pressure value is determined based on the fingertip pulse wave detected as a change in fingertip impedance or a change in transmitted light. Cuff 2
4 is wrapped around the upper arm, the blood pressure value may be determined based on the origin or disappearance of the so-called Korotkoff sound.

Furthermore, a display device such as a printer or an image display may be provided for plotting the measured values continuously and repeatedly obtained in the above-described embodiments on a time axis. In this way, blood pressure monitoring becomes easy.

In addition, in the embodiment shown in FIG. 1, the cuff 24 is configured to be lowered to the pressure in the second tank 30 which is controlled to be lower than the measured value by a certain value, but the pressure in the second tank 30 is lowered by a predetermined value. Alternatively, the cuff pressure may be controlled to a constant value, and the cuff pressure may be lowered to the constant value.

Furthermore, although the first tank 14 and the second tank 30 are provided in the above-mentioned embodiments, these do not necessarily have to be provided as long as the pressure of the cuff 24 is controlled as described above with a pressure control valve or the like. It's good.

In addition, a pressure sensor is provided in the first tank 14, and the air pump 10
can be controlled by feedback.

The above-mentioned is merely one embodiment of the present invention, and the present invention may be modified without departing from the spirit thereof.
Various changes may be made therein.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an example of an apparatus to which the present invention is applied. 2 and 3 are flowcharts for explaining the operation of the embodiment of FIG. 1. FIG. 4 is a timing chart illustrating the operation of the embodiment shown in FIG. FIG. 5 is a diagram showing the cuff pressure changed by the operation of the embodiment of FIG. 1. 6, 7, 8, and 9 are views corresponding to FIGS. 1, 2, 4, and 5, respectively, in an apparatus to which other aspects of the present invention are applied. be. 24: Cuff Applicant Nippon Cowan Co., Ltd. Figure 2 Figure 4 Figure 5 Time Figure 8 Figure 9 Series

Claims (2)

[Claims] (1) A method of continuously measuring the blood pressure of a living body by repeatedly compressing a part of the living body with a cuff, the cuff being gradually pressurized and the blood pressure being measured during this pressurization. and a rapid blood pressure lowering step in which the cuff is rapidly evacuated after the blood pressure value is obtained, and the blood pressure is lowered to a predetermined value lower than the blood pressure value and higher than atmospheric pressure. Continuous blood pressure measurement method. (2) A method of continuously measuring the blood pressure of a living body by repeatedly compressing a part of the living body with a cuff, the cuff being gradually pressurized and the blood pressure being measured during this pressurization. step, after the pressure in the cuff reaches a value higher by a predetermined value than the blood pressure value obtained during the pressure increase step, the cuff is gradually evacuated, and the blood pressure value is measured during this pressure reduction step. and a step of starting the pressure increasing step when the pressure in the cuff reaches a value lower by a predetermined value than the blood pressure value obtained during the blood pressure lowering step. A continuous blood pressure measurement method characterized by repeatedly performing the following steps.