JP2664918B2 - Blood pressure monitoring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a blood pressure monitoring device of a type for monitoring a blood pressure value based on a pulse wave detected by a pulse wave sensor from a relationship obtained in advance.

2. Related Art and its Problems In general, when measuring blood pressure, a part of a living body is pressed with a cuff or the like to detect a pressure vibration wave (pulse wave) of the cuff generated in synchronization with the heartbeat of the living body, and the pressure is measured. A blood pressure value is determined based on a change in the magnitude of the vibration wave.

However, when such a method is used for a living body that requires continuous monitoring of blood pressure for a long time, such as a patient after surgery, a part of the living body will be continuously pressed for a long time, It causes considerable pain to the living body.

Means for Solving the Problems The present invention has been made in view of the above circumstances as an object to provide a blood pressure monitoring device in which discomfort given to a living body when monitoring the blood pressure of the living body is greatly reduced. The gist of the blood pressure value is to determine the blood pressure value of the living body based on the pulse wave detected by the pulse wave sensor from the relationship between the magnitude of the pulse wave and the blood pressure value, which is obtained in advance. A blood pressure monitoring device for monitoring a blood pressure value of a living body based on the blood pressure value determined by the blood pressure value determining means, comprising: (a) a cuff for compressing a part of a living body; Blood pressure measuring means for measuring the maximum and minimum blood pressure values of the living body from the compression pressure of the cuff at the time of generation and disappearance of the Korotkoff sound generated in the process of pressure change due to compression; and (b) determined by the blood pressure measurement means. The highest and lowest blood pressure values obtained, the maximum value and the minimum value of the pulse wave detected by the pulse wave sensor at the time when the highest and lowest blood pressure values are determined, a relationship determining means for determining the relationship, Is to include.

In this way, the blood pressure measurement means, the highest and lowest blood pressure values measured from the cuff compression pressure at the time of the occurrence and disappearance of Korotkoff sound generated in the process of pressure change due to cuff compression, The relationship between the magnitude of the pulse wave and the blood pressure value is determined by the maximum value and the minimum value of the pulse wave detected by the pulse wave sensor at the time when the maximum and minimum blood pressure values are determined.

Therefore, by using the apparatus of the present invention, for example, the actual maximum and minimum blood pressure values are measured in advance or periodically at regular intervals by the blood pressure measurement means, so that the pulse values are determined when the blood pressure values are determined. The relationship between the maximum value and the minimum value of the pulse wave detected by the wave sensor is determined, and the blood pressure value is determined from the relationship based on the pulse wave detected by the pulse wave sensor. Even when monitoring blood pressure values continuously,
Since it is not necessary to continuously compress a part of the living body to determine the blood pressure value, it is possible to prevent the blood circulation of the living body from being inhibited, and to greatly reduce the pain given to the living body. is there. Further, the relationship between the blood pressure value and the pulse wave is determined each time an actual blood pressure value is detected based on the pulse wave detected at the time when the blood pressure value is determined. The relationship is always accurately obtained, and the accuracy of the blood pressure measurement is sufficiently obtained.

Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a view for explaining the configuration of the blood pressure monitoring device of the present embodiment. In the figure, a rubber bag-shaped cuff 10 which is wound around an upper arm of a living body and presses the same has a microphone 12 inside. Is provided. A pressure sensor 14, a switching valve 16, and an electric pump 18 are connected to the cuff 10 via a pipe 19. The microphone 12 detects a pulse sound (Korotkoff sound) generated from the upper arm of the living body, and supplies a pulse sound signal SO representing the pulse sound to the band-pass filter 20. The band-pass filter 20 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 24 via the A / D converter 22. The pressure sensor 14 detects a pressure (cuff pressure P) in the cuff 10 and outputs a cuff pressure signal SP representing the cuff pressure P to the CPU 24. The switching valve 16 adjusts the cuff pressure P by switching between the cuff 10 and the electric pump 18 between a pressure supply state, a slow exhaust state, and a rapid exhaust state. That is, in the pressure supply state, the slow exhaust port and the rapid exhaust port of the switching valve 16 are closed, pressure is supplied from the electric pump 18 to the cuff 10, and the cuff pressure P reaches a predetermined target cuff pressure. Then, the state is switched to the slow exhaust state, and the inside of the cuff 10 is evacuated from the slow exhaust port provided with the throttle at a predetermined speed appropriate for the predetermined blood pressure measurement, and the blood pressure is reduced during the slow down pressure period of the cuff 10. Simultaneously with the measurement, the state is switched to the quick exhaust state, and the inside of the cuff 10 is quickly exhausted from the quick exhaust port.

The CPU 24 is connected to the ROM 26, RAM 28, I / O
The drive circuit 31 is connected to the port 27, executes signal processing using the temporary storage function of the RAM 28 according to a program stored in the ROM 26 in advance, and is connected to the electric pump 18.
The start / stop of the electric pump 18 is controlled by controlling the power supply from the drive circuit 31 to the electric pump 18 by supplying an ON / OFF signal to the control circuit 31 and a command signal is output to the switching valve 16 for switching. By performing the operation, the cuff pressure P is adjusted as described above. At the same time, the CPU 24 executes a series of blood pressure measurement operations, and determines the cuff pressure P when the Korotkoff sound is generated and disappears as the systolic blood pressure value and the diastolic blood pressure value based on the pulse sound signal SO and the cuff pressure signal SP, respectively. At the same time, the blood pressure display 29 displays the determined blood pressure value. The blood pressure display 29 has a horizontal axis 21 and a vertical axis according to the display signal supplied from the CPU 24 as shown in FIG.
A bar graph 25 in which the upper end A and the lower end B represent a systolic blood pressure value and a diastolic blood pressure value, respectively, is provided on a CRT provided with a two-dimensional chart 23 representing time and blood pressure (mmHg), respectively.
Are displayed sequentially and continuously.

Further, a pulse wave sensor 32 is connected to the CPU 24 via an A / D converter 34. As shown in FIG. 4, the pulse wave sensor 32 is attached to a band 36 provided with a pair of fasteners (not shown) at both ends thereof. By placing the band 36 around the wrist of the living body and placing the fastener in close contact with each other, the band 36 is locally pressed with a constant pressure of about 10 to 100 mmHg against the radial artery located on the radius. It has become. That is, the pulse wave sensor 32 detects a pulse wave from the radial artery, and supplies a pulse wave signal SM representing the pulse wave to the CPU 24 via the A / D converter 34. As the pulse wave sensor 32, a semiconductor strain sensor or a piezoelectric element for converting a pulse wave of an artery into an electric signal is used. The pulse wave sensor 32
Is attached to the wrist of the arm opposite to the arm on which the cuff 10 is wound. Further, a pulse signal CK having a predetermined frequency is supplied from the clock signal source 38 to the CPU 24.

FIG. 1 is a functional block diagram for explaining a main part of a control function of an arithmetic control circuit of the blood pressure monitor device of the present embodiment.
In FIG. 1, the blood pressure measuring means 50 compresses a part of the living body with the cuff 10 and calculates the biological The highest blood pressure value H and the lowest blood pressure value L are measured. The relation determining means 52 includes a systolic blood pressure value H and a diastolic blood pressure value L determined by the blood pressure measuring means 50, and a maximum value M _max and a maximum value M _max of the pulse wave detected by the pulse wave sensor 32 at the time when the blood pressure values are determined. The relationship between the magnitude of the pulse wave and the blood pressure value is determined based on the minimum value _Mmin . Blood pressure value determination means 54
Determines the blood pressure value of the living body based on the pulse wave M detected by the pulse wave sensor 32 from the relationship between the pulse wave size and the blood pressure value obtained in advance by the relation determining means 52.

Hereinafter, the operation of this embodiment will be described with reference to the flowchart of FIG.

First, when a power switch (not shown) is turned on, step S1 is executed, and it is determined whether or not a start / stop push button (not shown) is pressed, that is, whether or not a start / stop signal is supplied to the CPU 24. When the start / stop signal is output after the cuff 10 is wound around the upper arm of the living body or the like, step S2 is executed next, the count value T of the timer is reset to zero, and then supplied again from the clock signal source 38. The counting of the pulse signal CK is started. Subsequently, step S3 is executed, the switching valve 16 is switched so as to be in the pressure supply state, and the pressure fluid is supplied from the electric pump 18 to the cuff 10. Thus the cuff pressure P is increased, whether the host vehicle has reached the target cuff pressure P ₁ to the cuff pressure P is predetermined in step S4 is determined. In the target cuff pressure P ₁ is expected pressure higher than the systolic blood of a living body, for example, is set to about 180 mmHg, the cuff pressure P reaches the target cuff pressure P _1, followed by step S5 is executed You. In step S5, the electric pump 18 is stopped and the switching valve 16
Is switched to the slow exhaust state, and the cuff pressure P is gradually decreased. Then, in such a state, step S6 is executed, and it is determined whether or not a pulse wave has been detected by the pulse wave sensor 32, and if it is determined that the pulse wave has not been detected, the process waits until it is detected. However, if it is determined that a pulse wave has been detected, a series of detected pulse waves are sequentially stored in the RAM 28 in step S7.

Subsequently, the blood pressure measurement routine of step S8 corresponding to the blood pressure measurement means 50 of the present embodiment is executed, and the cuff 10 is cuffed based on the generation and disappearance of the Korotkoff sound represented by the pulse wave signal SO in the slow down period. The systolic blood pressure value H (mmHg) and the diastolic blood pressure value L (mmHg) are determined from the pressure signal SP, and the actual blood pressure values H and L are stored in the RAM 28. Next, it is determined whether or not the maximum and minimum blood pressure values are determined by executing step S9,
Once the systolic and diastolic values have been determined, step
By executing S10, the switching valve 16 is switched to the rapid exhaust state, and the inside of the cuff 10 is quickly exhausted. However, if the determination is denied, steps S6 and subsequent steps are executed again.

Followed in step S11, from among the series of pulse wave stored until then in the RAM 28, is read blood pressure H and L pulse wave M _H and M _L at the time determined pulse wave in step S8 M with a minimum value M _min of the maximum value M _max and M _L of _H is determined respectively, a relational expression for determining a systolic blood pressure value SYS and the diastolic blood pressure value DIA respectively on the basis of their maximum value M _max and the minimum value M _min SYS = _KMmax + a (1) DIA = _KMmin + a (2) The constants K and a in (2) are determined. That is, by substituting the actual blood pressure values H and L determined in step S8 into the systolic blood pressure value SYS and the diastolic blood pressure value DIA,
The constants K and a are calculated. Here, the equations (1) and (2) represent the maximum and minimum blood pressure values determined based on the occurrence and disappearance of the Korotkoff sound, the maximum value of the pulse wave at the time of occurrence of the Korotkoff sound, and the disappearance of the Korotkoff sound. It is established based on the fact that a proportional relationship is established between the time and the lowest value of the pulse wave. Therefore,
The constants K and a represent the slope and the intercept of the Y axis, respectively, when the blood pressure value is on the Y axis and the magnitude of the pulse wave is on the X axis. Since the blood pressure value is not always zero even when the magnitude of the pulse wave is zero by adding the Y-intercept a, the relationship between the blood pressure value and the pulse wave becomes accurate.

Next, in step S12, followed by whether the pulse wave is detected is determined, if it is determined to have been detected, are the following step S13 is executed, pulse M ₁ that has been detected maximum value m _max and a minimum value m _min of the pulse wave M ₁ is determined with read. In step S14, since K and a have already been determined in step S11, these maximum value m _max and minimum value m _min
Is substituted into the preceding equations (1) and (2) to estimate the systolic blood pressure value SYS and the diastolic blood pressure value DIA,
In step S15, the systolic blood pressure value SYS and the diastolic blood pressure value DIA are displayed on the blood pressure display 29. Therefore, in the present embodiment, step S14 corresponds to the blood pressure value determining means 54.

In step S16, it is determined whether the start / stop button has been operated again. If it is determined that the operation has been performed again, the process returns to step S1, but if it is determined that the operation has not been performed again, step S17 is executed, and the count T of the timer is set to the predetermined count T. _It is determined whether or not ₀ has been reached. The counting contents T ₀ is the step S11
In order to correct the correspondence determined in
And a corresponding to a time interval for re-determining a, and is set to, for example, about 5 to 10 minutes. Therefore, when the count T reaches T ₀ , the steps S2 and below are executed again.At this stage, however, the count T does not yet reach T ₀ , and the steps S12 and below are executed, and a series of pulse wave M ₂ followed by M _1, M _3, systolic blood pressure every time ...... is detected
SYS and diastolic blood pressure value DIA are estimated and displayed continuously.

As described above, in the process of repeating the operation from step S12, the count value T of the timer is set to T _{0 in} step S17.
Is reached, the steps S2 and subsequent steps are executed again, so that the actual systolic blood pressure value H and the diastolic blood pressure value L newly determined in the step S8 and the blood pressure values H and L respectively become On the basis of the maximum value and the minimum value of the pulse wave at the determined time, the constants K and a of the corresponding relational expressions (1) and (2) are calculated again in step S11, and the new corresponding relational expression (1) and The blood pressure measurement is continuously performed based on the maximum value and the minimum value of the pulse wave detected subsequently from (2), and the measured blood pressure value is displayed. Therefore, in the present embodiment, step S11 corresponds to the relationship determining means 52.

As described above, in the present embodiment, the systolic blood pressure value H measured from the cuff pressure P at the time of the generation and disappearance of the Korotkoff sound generated in the process of pressure change due to the compression of the cuff 10 at regular time intervals, and The minimum blood pressure value L, the maximum value m _max and the minimum value of the pulse wave detected by the pulse wave sensor 32 at the time when the maximum blood pressure value H and the minimum blood pressure value L are determined.
By and m _min, is the relationship between the size and the blood pressure values of the pulse wave is determined. Therefore, according to the present embodiment, the actual peak and diastolic blood pressure values are measured at regular time intervals, so that the pulse wave sensor 32
Is determined based on the pulse wave detected by the pulse wave sensor 32, and the blood pressure value of the living body is determined over a long period of time. Even when the value is continuously monitored, it is not necessary to continuously compress a part of the living body to determine the blood pressure value, and it is possible to prevent the blood circulation of the living body from being inhibited, The pain given to the living body is greatly reduced. Further, the relationship between the blood pressure value and the pulse wave is determined each time an actual blood pressure value is detected based on the pulse wave detected at the time when the blood pressure value is determined. The relationship is always accurately obtained, and the accuracy of the blood pressure measurement is sufficiently obtained.

Further, according to the present embodiment, since the systolic blood pressure value and the diastolic blood pressure value of the living body can be measured simultaneously and continuously for each pulse of the artery, there is an advantage that high-density medical information can be obtained. In the present embodiment, it is of course possible to configure so as to continuously measure only one of the systolic blood pressure value or the diastolic blood pressure value, and it is also possible to configure so as to continuously measure the average blood pressure value or the like. .

In the present embodiment, the K-tone method is adopted as a blood pressure measurement method, so that the highest and lowest blood pressure values are determined almost simultaneously with the generation and disappearance of the Korotkoff sound. There is an advantage that the correspondence relationship with is easily and quickly obtained.

Next, another embodiment of the present invention will be described. In the following embodiments, portions common to the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 6, a state in which the correspondence between the upper arm blood pressure value and the pulse wave determined in step S11 seems to be shifted, for example, a body motion of the pulse wave detector near the wrist or a change in peripheral blood flow resistance. If such is determined from the pulse wave, a step S18 for re-determining the relationship may be provided.
When the pulse wave detecting unit moves and the pressing condition of the pulse wave sensor 32 changes, or when the peripheral blood flow resistance changes due to contraction or dilation of the peripheral blood vessels, the brachial blood pressure value and the pulse wave of the radial artery are changed. This is because the correspondence relationship with the blood pressure value determined in this way is shifted. The above step S18 is provided, for example, between steps S13 and S14 in FIG. 5, and determines whether the radial pulse wave is abnormal. In this step S18, for example, regarding the body motion of the pulse wave detection unit, the amplitude of the radial pulse wave, the magnitude from the base line (for example, the zero volt line) to the peak value of the radial pulse wave within a unit time (for example, 5 seconds) It is judged as abnormal when it changes by 50% or more. Alternatively, it is determined to be abnormal when the generation time of the radial pulse wave deviates from the normal generation cycle by, for example, 30% or more.
Regarding the change in the peripheral blood flow resistance, as shown in FIG. 7, the value shown at the position of the notch (notch) with respect to the radial pulse wave (for example, the size A / An abnormality is determined when the size B) from the notch to the lower peak value changes by 30% or more within a unit time. Alternatively, it is determined to be abnormal when the rate of change (inclination) of a part of the radial pulse wave corresponding to the diastolic phase (falling part C after the notch) greatly changes. Alternatively, the difference between the blood pressure value based on the radial pulse wave and the blood pressure value based on the subsequent radial pulse wave when the relationship between the magnitude of the radial pulse wave and the brachial blood pressure values H and L is determined in step S11 is, for example, It is judged as abnormal when it changes by 40mmHg or more.

As mentioned above, although one Example of this invention was described based on drawing, this invention can be implemented suitably also in another aspect.

In the above-described embodiment, the pulse wave is collected from the radial artery near the wrist of the living body. However, since it is located relatively close to the body surface, other blood vessels from which the pulse wave can be easily collected, for example, the carotid artery and the dorsal foot artery Alternatively, a pulse wave may be detected from a finger blood vessel or the like.

In the above-described embodiment, the pulse wave sensor 32 is
It is fixed on the radial artery wave near the wrist by 36 and is pressed with a constant pressing force against the radial pulse wave, but as shown in FIG. That is, a small cuff 40 configured substantially similarly to the cuff 10 is wound around, for example, the fingers of the hand on the blood pressure measurement side and the reaction side, and a pressurized fluid is supplied from the electric pump 42 into the cuff 40 so that the inside of the cuff 40 is The pressure is increased to a predetermined pressure, and the cuff 40 is synchronized with the pulse of the living body.
The pressure vibration generated inside may be detected by a pressure sensor 46 connected to the cuff 40 through the air pipe 44. At this time, a pressure regulating valve 48 controlled by the CPU 24 is attached to the air pipe 44, and the magnitude of the pulse wave vibration output from the pressure sensor 46 to the CPU 24 in response to the pressure vibration in the cuff 40. For example, the amplitude, signal power, etc. are calculated by the CPU 24 and whether or not the magnitude is saturated is detected. When the magnitude is saturated, the pressure regulating valve 48 is controlled so that the pressure in the cuff 40 at that time is maintained. Feedback control is performed. Note that the cuff pressure is not changed so that the magnitude of the pulse wave signal is saturated.
It can be controlled so that the inside is maintained at a predetermined suitable pressure.

In addition, instead of the band 36, a fluid container that houses the pulse wave sensor 32, and a diaphragm made of rubber or the like that fixes the pulse wave sensor 32 so as to be in contact with the surface of a living body in the fluid container and seals the inside of the fluid container The fluid container and the diaphragm are fixed directly above the blood vessel on the surface of the living body, and when a pressure fluid regulated by a pressure regulating valve or the like is supplied into the fluid container, the pulse wave sensor 32 is actuated by the action of the diaphragm.
Is pressed against the blood vessel with a suitable pressing force, so that a pulse wave can be detected. In addition, the pulse wave sensor 32 is provided inside the fluid container, on the fluid container, or outside the fluid container, and by closing the contact surface of the fluid container with the living body with the diaphragm, through the fluid in the fluid container and the diaphragm. Alternatively, a pressure vibration wave corresponding to the pulse wave may be detected by the pulse wave sensor.

Also, for example, an electrode is fixed at two positions separated by a predetermined distance in a part of a living body such as a finger, and a weak current is applied to the finger to cause vibration corresponding to a pulse wave from impidus generated between the two electrodes. Waves may be detected. Furthermore, a light emitter and a light receiver are provided above and below a relatively thin part such as a finger, and light projected so as to pass through a blood vessel located at the part is received by the light receiver,
The pulsation of the blood vessel can be detected from the change in the wavelength of the received light. In the above method, when a pulse wave is detected from an arm or a hand, the pulse wave sensor is provided on the arm or hand on the side opposite to the side on which the blood pressure value is measured.

In the above-described embodiment, the correspondence between the actual blood pressure value and the magnitude of the pulse wave is determined on the assumption that the actual blood pressure value is proportional to the magnitude of the pulse wave. From a plurality of types of data maps representing the correspondence between the blood pressure value and the pulse wave magnitude, which are obtained by calculating the correspondence represented by the following formula, the blood pressure value and the pulse wave magnitude of the living body as the subject are measured. The correspondence may be obtained by other methods, such as obtaining a correspondence by selecting one data map based on the data.

In the above-described embodiment, the slope K and the Y intercept a are used in the correspondence between the blood pressure value and the magnitude of the pulse wave. However, even when only the slope K is used, the accuracy of the blood pressure measurement is sufficiently high. Is obtained. In this case, the proportional relationships between the systolic blood pressure value SYS and the maximum value of the pulse wave and the diastolic blood pressure value DIA and the minimum value of the pulse wave are different from each other, and two types of slopes K may be obtained. .

Further, in the above-described embodiment, in the blood pressure measurement unit, the blood pressure value is determined in the process of lowering the pressure of the cuff 10 based on the occurrence and disappearance of the Korotkoff sound collected by the microphone 12, but in the process of increasing the pressure of the cuff 10, It is also possible to perform a blood pressure measurement.

Further, in the above-described embodiment, the continuously measured highest and lowest blood pressure values are displayed on the CRT, but may be printed and recorded on a recording paper such as a chart at the same time, Other various display means or storage means may be employed.

The above is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit thereof.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention. FIG. 2 is a diagram for explaining the configuration of a blood pressure monitoring device according to one embodiment of the present invention. FIG. 3 is a diagram showing an example of a trend of the blood pressure value displayed on the blood pressure display in FIG. FIG. 4 is a view showing a state where the pulse wave sensor of FIG. 2 is mounted on a wrist of a living body. FIG. 5 is a flowchart for explaining the operation of the apparatus shown in FIG. FIG. 6 is a flowchart for explaining the main part of the operation of another embodiment of the present invention. FIG. 7 is a view for explaining a position corresponding to a notch position of a pulse wave or a diastole. FIG. 8 is a view for explaining the configuration of a pulse wave sensor employed in another embodiment of the present invention. 10: Cuff 32: Pulse wave sensor 46: Pressure sensor Step S8: Blood pressure measuring means Step S11: Relationship determining means Step S14: Blood pressure value determining means

Claims (1)

(57) [Claims] 1. A blood pressure value determining means for determining a blood pressure value of a living body based on a pulse wave detected by a pulse wave sensor from a previously determined relationship between a magnitude of a pulse wave and a blood pressure value. What is claimed is: 1. A blood pressure monitoring device for monitoring a blood pressure value of a living body based on a blood pressure value determined by determination means, comprising: a cuff for compressing a part of a living body; Blood pressure measuring means for measuring the maximum and minimum blood pressure values of the living body from the compression pressure of the cuff at the time of sound generation and disappearance; the maximum and minimum blood pressure values determined by the blood pressure measurement means; and the maximum and minimum blood pressure values A blood pressure monitor device comprising: a relation determining means for determining the relation based on the maximum value and the minimum value of the pulse wave detected by the pulse wave sensor at the time when is determined.