JP2675824B2 - Pulse wave monitor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a pulse wave monitor that detects and continuously displays a pulse wave of a living body.

Prior art By fixing the pulse wave sensor etc. on the artery because it is relatively close to the epidermis such as the radial artery on the surface of the living body, and pressing the pulse wave sensor against the artery with an appropriate pressing force, A pulse wave monitor device of a type that detects a pressure pulse wave generated as an artery expands / contracts in synchronization with a heartbeat and continuously displays the pressure pulse wave has been considered. In this way, the pressure pulse wave detected by pressing the pulse wave sensor against the artery is relatively close to the pulse wave detected directly from the artery, so that the state of the living body can be accurately grasped. Therefore, it is desirable to continuously monitor such pressure pulse wave.

However, in such a pulse wave monitoring device, when the living body falls into a shock state during surgery, for example, the pressure pulse wave detected by the pulse wave sensor has an extremely small amplitude. Therefore, there is a problem in that the state of the heartbeat cannot be accurately grasped from such a pressure pulse wave display.

Means for Solving the Problems The present invention has been made in the background of the above circumstances, and the gist thereof is to obtain the pulse wave in order to continuously monitor the pulse wave of the living body. A pulse wave monitoring device for continuously displaying on a display device, comprising: (a) an electrode attached to the epidermis of the living body, which continuously detects impedance in a portion to which the electrode is attached, Impedance pulse wave detecting means for generating an impedance pulse wave signal representing impedance; and (b) a pressure pulse wave signal representing the pressure pulse wave detected by detecting the pressure pulse wave generated in the artery by being pressed by the artery of the living body. Pressure pulse wave detection means for generating
(C) The pressure pulse wave detected by the pressure pulse wave detecting means is constantly displayed on the display, but when the pressure pulse wave detection by the pressure pulse wave detecting means becomes abnormal, the pressure pulse wave is detected. And a control means for displaying the impedance pulse wave detected by the impedance pulse wave detection means.

In this way, the control unit normally displays the pressure pulse wave detected by the pressure pulse wave detection unit on the display, but when the pressure pulse wave detection becomes abnormal, The impedance pulse wave detected by the impedance pulse wave detecting means is displayed instead of the pressure pulse wave. Therefore, according to the present invention, for example, when the pressure pulse wave detected when the living body is in a shock state or the like is very small, it is determined that the control means is abnormal, and the indicator indicates the shock state of the living body. However, since the impedance pulse wave whose pulsation is relatively clear is displayed, it is possible to obtain an effect that an accurate pulse wave is always displayed.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram for explaining the configuration of the pulse wave monitoring device of this embodiment. A pulse wave detection probe 12 is mounted on the artery 10 located on the radius of the wrist of one arm of the living body. The pulse wave detection probe 12 is designed to be fixed on the artery 10 by the support band 14 being wound around the wrist and fastened, and as shown in detail in FIG. High rectangular container-shaped housing 16 and pulse wave sensor housed in the housing 16 so as to contact the epidermis of a living body.
18, an annular diaphragm 20 made of rubber or the like that is interposed between the side wall of the housing 16 and the pulse wave sensor 18 to support the pulse wave sensor 18 with respect to the housing 16 and seal the opening surface of the housing 16. It consists of

An electric pump 24 is installed in the housing 16 through a pipe 22.
A pressure fluid is supplied from the pressure control valve 26 through the pressure control valve 26. That is, when the pressure fluid is supplied from the electric pump 24 into the housing 16, the diaphragm 20 expands toward the surface of the living body as the pressure P ₁ inside the housing 16 rises. Artery 10
Is pressed against. The pulse wave sensor 18, which is composed of a semiconductor pressure detecting element and the like, expands the artery 10 synchronized with the pulsation of the heart by being pressed against the living body.
Detecting a pressure pulse wave generated with the shrinkage, and outputs a pressure pulse wave signal SM _P representing the pressure pulse wave with respect to CPU30 through a band-pass filter 27 and A / D converter 28. Therefore, in this embodiment, the pulse wave sensor 18 functions as a pressure pulse wave detecting means.

The pressure regulating valve 26 is for regulating the pressure fluid from the electric pump 24, and is a rapid pressurizing state in which the pressure P ₁ in the housing 16 is rapidly increased until a predetermined lower limit value P _{L of} about 20 mmHg is reached, Gradually increasing pressure P ₁ from its lower limit value P _L to a predetermined upper limit value P _{H of} about 80 mmHg at a predetermined speed of about 5 to 6 mmHg / sec which is suitable for pulse wave detection. , A rapid exhaust pressure state in which the inside of the housing 16 is rapidly exhausted, and a pressure maintaining state in which the inside of the housing 16 is maintained at a constant pressure. Also, the housing 16
A pressure sensor 32 is connected in a pipe 22 between the pressure regulating valve 26 and the pressure regulating valve 26, and outputs a pressure signal SP ₁ representing the pressure P in the housing 16 to the CPU 30 via the A / D converter 3.

Further, in the forearm of the arm on the side where the pulse wave sensor 18 is attached, a pair of electrodes 36 and 38 are respectively attached at predetermined two positions separated by a predetermined distance and connected to the differential amplifier 40. Has been done. Electrodes 44 and 46 connected to an AC constant-current power supply 42 are attached in proximity to these electrodes 36 and 38, respectively. Therefore, a constant weak current is made to flow between the electrodes 44 and 46, and a voltage is supplied from the electrodes 36 and 38 to the differential amplifier 40. The impedance developed between the electrodes 36, 38 is detected, not least because the voltage at is reduced. Then, from the differential amplifier 40, an impedance pulse wave signal SM ₁ representing the impedance between the electrodes 36 and 38 is output to the band pass filter 48, and the impedance pulse wave filtered by the band pass filter 48 is also output. Signal SM ₁ is A / D
It is supplied to the CPU 30 via the converter 50 and sequentially stored in the RAM 70 described later. Therefore, in this embodiment, the differential amplifier 40 functions as impedance pulse wave detecting means.

In addition, a bag-like cuff 52 is wound around the upper arm of the other arm of the living body. A pressure fluid is supplied from the electric pump 56 into the cuff 52 through a pipe 54 through a pressure regulating valve 58, and the pressure in the cuff 52 (cuff pressure) P ₂
The upper arm is pressed by raising. A pressure sensor 60 is connected in the pipe 54 between the cuff 52 and the pressure regulating valve 58, and a pressure signal SP ₂ representing a pressure fluctuation in the cuff 52 is supplied from the pressure sensor 60 to the pulse wave detection circuit 62. And to the cuff pressure detection circuit 64. The pulse wave detection circuit 62 discriminates the pulsating component in the pressure signal SP ₂ and supplies the pulse wave signal SM to the CPU 30 via the A / D converter 66. The cuff pressure detection circuit 64 discriminates the static pressure component in the pressure signal SP ₂ , that is, the cuff pressure component, and supplies the cuff pressure signal SP _C to the CPU 30 via the A / D converter 68. Further, the pressure regulating valve 58 has a cuff pressure P ₂ of 180 m, which is expected to be higher than the maximum blood pressure of the living body.
Rapid increase in pressure to a predetermined target cuff pressure P _m of about mHg, and a cuff pressure P ₂ is gradually reduced at a predetermined speed of about 3 to 4 mmHg / sec, which is suitable for blood pressure measurement. The cuff pressure P ₂ is adjusted by switching to a gradual pressure reduction state and a rapid pressure reduction state in which the cuff pressure P ₂ is rapidly lowered.

The CPU 30 constitutes a so-called microcomputer together with the RAM 70 and the ROM 72, uses the storage function of the RAM 70, processes an input signal according to a program stored in the ROM 72 in advance, and executes a blood pressure measurement operation. That is, the CPU 30 has the drive circuit 73 connected to the electric pump 56.
An ON / OFF signal is supplied via the output interface 76 to control the electric power supply from the drive circuit 73 to the electric pump 56, thereby controlling the start and stop of the electric pump 56, and via the output interface 76. By supplying a command signal to the pressure regulating valve 58 by increasing the cuff pressure P ₂ to the target cuff pressure P _m , the cuff pressure P ₂ is gradually decreased at the predetermined speed, and the magnitude of the pulse wave generated in the slow depressurization period is increased. The actual maximum blood pressure value H and the minimum blood pressure value L are determined from the cuff pressure SP ₂ represented by the cuff pressure signal SP _C based on the change of
It is stored in 0.

Further, the CPU 30 has a drive circuit 7 connected to the electric pump 24.
The ON / OFF signal is supplied to the electric pump 24 via the output interface 76 to control the electric power supply from the drive circuit 74 to the electric pump 24, thereby controlling the start and stop of the electric pump 24 and the output interface 76. By supplying a command signal to the pressure regulating valve 26 via FIG.
As shown in (b) and (b) respectively, after the pressure P ₁ in the housing 16 is rapidly increased to the lower limit value P _L , the pressure P ₁ is maintained as it is for a period A of about 2 seconds, and then gradually increased at the predetermined speed. Speed up. During the gradual boosting period B, the pressure pulse wave detected by the pulse wave sensor 18 and the pressure sensor
The pressure P ₁ detected by 32 is sequentially stored in the RAM 70, the magnitude of the pressure pulse wave is calculated, and the housing 16 when the maximum pressure pulse wave M _Pmax having the maximum magnitude is generated.
The internal pressure P _1max is determined, and the pressure regulating valve 26 is switched to the rapid exhaust pressure state and the pressure maintaining state so that the pressure P _1max is maintained and operated by feedback control.
Incidentally, the lower limit value P _L and the upper limit value P _H is experienced that the pressure P _1max in the housing 16 when the pressure pulse wave becomes maximum is within a predetermined range of approximately 20~80mmHg through individual measured person From the above, it is about 20 mmHg and
It has been determined to be 80 mmHg. By setting the lower limit value P _L and the upper limit value P _H as described above and determining the maximum pulse wave M _Pmax , the pressure _rising period in the housing 16 is relatively shortened to about 10 seconds, so that the pressure P _1max is There are advantages that the time required for the calculation is shortened and the discomfort given to the person to be measured is reduced.

Further, the CPU 30 has the housing 1 determined as described above.
The pressure pulse wave detected in the state where the pressure P _{1max in} 6 is maintained is sequentially stored in the RAM 70, and based on the pressure pulse wave, a predetermined correspondence relationship between the pressure pulse wave and the blood pressure value is determined. The blood pressure value is continuously determined from and displayed on the blood pressure display 78. As shown in FIG. 4, the blood pressure indicator 78 has a horizontal axis 80 and a vertical axis 82 on the cathode ray tube provided with a two-dimensional chart showing time and blood pressure (mmHg), respectively, according to the display signal supplied from the CPU 30. A bar graph 84 showing the systolic blood pressure value and the diastolic blood pressure value at the lower end B are successively and successively displayed.

Further, the CPU 30 supplies a command signal to the waveform display 88 via the output interface 76, so that the horizontal axis 92 and the vertical axis 94 in the waveform display 88 respectively indicate time and pulse as shown in FIG. The waveform of the pressure pulse wave (shown by the solid line) normally detected by the pulse wave sensor 18 is normally and continuously displayed on a CRT provided with a two-dimensional diagram showing the wave amplitude. However, when the CPU 30 determines that an abnormality has occurred in the pressure pulse wave detection by the pulse wave sensor 18, the impedance pulse wave waveform represented by the impedance pulse wave signal SM ₁ from the differential amplifier 40 (shown by a broken line). Is displayed instead of the pressure pulse waveform, and at the same time, when determining the blood pressure value continuously from the correspondence relationship between the pressure pulse wave and the blood pressure value as described above, the CPU 30 The blood pressure value is continuously determined by using the impedance pulse wave instead of the pressure pulse wave, based on the previously determined correspondence between the wave and the impedance pulse wave. Therefore, in this embodiment, the waveform display 88 functions as a display, and when the pressure pulse wave detection becomes abnormal, the CPU 30 for displaying the impedance pulse wave in place of the pressure pulse wave, the RAM 70, RO
M72 constitutes the control means. The CPU 30 is supplied with two types of pulse signals CK ₁ and CK ₂ of a predetermined frequency from the clock signal source 90.

The operation of the pulse wave monitoring apparatus of this embodiment will be described below with reference to the flowchart of FIG.

First, when a power switch (not shown) is turned on, step S1 is executed to determine 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 30. After the pulse wave detection probe 12 is attached to the wrist of one arm of the living body and the cuff 52 is attached to the upper arm of the other arm, and each electrode 36, 38, 44, 46 is attached to the forearm, respectively. When the start / stop signal is supplied, the pressure pulse wave detection routine of step S2 is then executed.

In the pressure pulse wave detection routine, as shown in FIG. 7, first, step SS1 is executed to start the operation of the electric pump 24, and at the same time, the pressure regulating valve 26 is switched to the rapid pressurization state, so that the pulse wave detection probe is activated. The pressure in the housing 16 of 12 is rapidly increased. Housing 1 in step SS2
It is determined whether the pressure P _{1 in} 6 has reached the lower limit value P _L. Initially, the pressure P ₁ does not reach the lower limit value P _L , so that the pressure P ₁ is made to wait and the pressure P ₁ is further rapidly increased. However, if it is determined that the pressure P ₁ has been reached, the subsequent step SS3 is executed. In step SS3, first, after the pressure P ₁ is maintained at the time lower limit value P _L corresponding to the period A, the pressure regulating valve 26 is switched to the gradually increasing pressure state so that the pressure P ₁ is gradually reduced at the predetermined speed. Boosted. During the period A, immediately after the pulse wave detection probe 12 is attached, the pressing surface of the pulse wave sensor 18 may not be brought into close contact with the artery 10 just above the artery 10, and noise or the like may be mixed. This is a waiting time for preventing normal pressure pulse wave detection from being hindered by noise or the like, and may be removed as necessary. In the subsequent step SS4, such housing 1
During the gradual boosting period B within 6, it is determined whether or not the pressure pulse wave is detected, and the process is kept waiting until the pressure pulse wave is detected. When it is determined that the pressure pulse wave is detected, the following step SS5 is executed, and the detected pressure pulse wave and the pressure P ₁ in the housing 16 at the time when the pressure pulse wave is generated are stored in the RAM 70. . In step SS6, whether the pressure P ₁ has reached the upper limit value P _H is determined. When still it is determined not to have reached, but step SS4 below is executed again, the pressure P ₁ in the course of the slow speed boosting upper limit value P _H
If it is determined that the following has been reached, the following step SS7 is executed. In step SS7, the pressure P _1max in the housing 16 at the time when the maximum pressure pulse wave M _Pmax, which is the largest pressure pulse wave among the pressure pulse waves detected in the gradual pressure increase period B, is determined, In the following step SS8, the pressure regulating valve 26 is switched to the pressure maintaining state after being brought into the rapid exhaust pressure state, and the pressure in the housing 16 is maintained at P _1max . Then, in this way, the pressure in the housing 16 is P
_The pressure pulse wave detected by the pulse wave sensor 18 is sequentially stored in the RAM 70 _while being maintained at _1max .

Returning to FIG. 6, in step S3, the counting content T _{1 of one} timer is reset and at the same time counting of _one pulse signal CK ₁ is started. In step S4,
When the operation of the electric pump 56 is started, the pressure regulating valve 58 is switched to the rapid pressure increasing state, and the pressure inside the cuff 52 is rapidly increased. Subsequently, step S5 is executed to determine whether or not the cuff pressure P ₂ has reached the target cuff pressure P _m , and if it is determined that the target cuff pressure P _m has not yet been reached, step S4 is executed again,
If it is determined that the arrival has been reached, the following step S6 is executed.
In step S6, the pressure inside the cuff 52 is gradually lowered at the predetermined speed, and in the next step S7, the cuff 52 is reduced.
It is determined whether or not the pressure vibration wave, that is, the pulse wave generated in the cuff 52 during the slow depressurization period is detected, and the process waits until it is detected. When it is determined that a pulse wave has been detected,
The pulse wave detected in the subsequent step S8 is stored in the RAM 70, and the blood pressure measurement routine of step S9 is executed. In the blood pressure measurement routine, the actual systolic blood pressure value H and the actual diastolic blood pressure value L are determined from the cuff pressure P ₂ based on the change in the magnitude of the pulse wave sequentially stored in the RAM 70, and the blood pressure values H are also determined. And L are stored in RAM 70. The blood pressure determination algorithm in step S9 is determined for example cuff pressure P ₂ at which the amplitude suddenly changes of the successive obtained pulse wave train, or the cuff pressure P ₂ at which the maximum value of the difference occurs in their amplitudes , to determine the systolic blood pressure value H and the diastolic blood pressure value L based on the relationship between the pre-cuff pressure P ₂ and blood pressure value determined on the cuff pressure P _2. Then, step S10 is executed to determine whether or not both the maximum and minimum blood pressure values H and L have been determined in step S9. Initially, the number of pulse waves required for blood pressure measurement has not been obtained, so steps S7 and below are executed again,
If it is determined that the blood pressure measurement has been completed, the next step
S11 is executed.

In step S11, the pressure pulse wave having the maximum amplitude that is sequentially detected and stored by the pulse wave sensor 18 being pressed against the artery 10 at the maximum pressure P _1max determined in step S2, It is determined whether or not the living body is abnormal due to a shock or the like. That is, the pressure pulse wave, when the living body receives a relatively large shock during surgery or the like to be in a shock state, since its amplitude becomes extremely small during the duration of the shock state, In step S11, a predetermined number N of pressure pulse waves generated within a time period corresponding to a period normally expected to continue the shock state are kept waiting in the RAM 70 until they are sequentially stored. At the time when the pressure pulse wave is stored, the average value of the amplitude value of the pressure pulse wave is calculated, and at the same time, the average value of the amplitude value of the series of impedance pulse waves in which a predetermined number N of pieces are similarly stored in the RAM 70 is calculated. Is calculated and the average value of the two is compared to determine the abnormality of the pressure pulse wave. That is, since the impedance pulse wave is not related to the shock state of the living body, when the difference obtained by subtracting the average value of the impedance pulse wave from the average value of the pressure pulse wave exceeds a predetermined allowable value α. It is determined that the pressure pulse wave is abnormal. As a result, step S12 is executed when it is determined that the pressure pulse wave is abnormal, and step S13 is executed when it is determined that the pressure pulse wave is normal.

In step S13, together with the pressure pulse wave M _P1 is read to be detected following a predetermined number of pressure pulse wave is determined to be normal in step S11, the maximum value m _Pmax and the minimum of the pressure pulse wave M _P1 The value m _Pmin is determined respectively, and the relational expression for obtaining the systolic blood pressure value SYS and the diastolic blood pressure value DIA based on the maximum value m _Pmax and the minimum value m _Pmin respectively: SYS = K · m _Pmax + a ( 1) DIA = K · m _Pmin + 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 S9 for the systolic blood pressure value SYS and the diastolic blood pressure value DIA,
The constants K and a are calculated. Here, these equations (1) and (2) are proportional to the maximum and minimum blood pressure values and the maximum and minimum blood pressure values of the pressure pulse wave, which are determined based on the change in the magnitude of the pulse wave, respectively. It is established based on the relationship. Therefore, the constants K and a
Indicates the slope and the intercept of the Y axis 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 does not always become zero even when the magnitude of the pulse wave is zero, the relationship between the blood pressure value and the pulse wave becomes accurate by adding the Y-intercept a.

Next, in step S14, it is determined whether or not the pressure pulse wave is detected following the pressure pulse wave M _P1, and if it is determined that the pressure pulse wave is detected, the following step S15 is executed and the detection is performed. Pressure pulse wave M _P2 is read and pressure pulse wave M
The highest value m _Pmax ′ and the lowest value m _Pmin ′ of _P2 are determined.
Then, in step S16, since the constants K and a have already been determined in step S13, by substituting the maximum value m _Pmax ′ and the minimum value m _Pmin ′ into the above equations (1) and (2), , Systolic blood pressure value SYS and diastolic blood pressure value DIA are determined. In step S17, while displaying the waveform of the pressure pulse wave M _{P2 on} the waveform display 88,
The blood pressure display 78 displays the blood pressure values SYS and DIA determined in step S16.

In the following step S18, it is determined whether or not the start / stop push button has been operated again. If it is determined that the re-operation has been performed, the process returns to step S1 again, but if it is determined that the re-operation has not been performed, step S19 is executed and the count content T _{1 of one} timer is predetermined. Count content
It is determined whether T ₀ has been reached. The count content T ₀ corresponds to the time interval for redetermining K and a in order to correct the correspondence determined in step S13, and is set to, for example, about 5 to 10 minutes. Therefore, when the count content T ₁ reaches T ₀ , steps S3 and subsequent steps are executed again, but since the count content T ₁ has not yet reached T ₀ at this stage, steps S14 and subsequent steps are executed. , A series of pressure pulse waves M _P3 , M _P4 , ... following M _P2
The systolic blood pressure value SYS and the diastolic blood pressure value DIA are determined each time when is detected, and the blood pressure value and the pulse wave shape are continuously displayed.

When it is determined in step S19 that the count content T _{1 of one} timer has reached T ₀ in the process in which the operations of step S14 and subsequent steps are repeatedly executed as described above, step S3 and subsequent steps are performed again. , The actual systolic blood pressure value H and diastolic blood pressure value L newly determined in step S9
And the maximum and minimum values of the pressure pulse wave read in step S13, the constants K and a of the corresponding relational expressions (1) and (2) are obtained again, and the new corresponding relational expression (1) is obtained. The blood pressure measurement is continuously performed based on the highest and lowest values of the pressure pulse wave detected subsequently from (2) and the measured blood pressure value and the pressure pulse wave shape are displayed.

Here, when the living body falls into a shock state during the operation as described above, the amplitude value of the pressure pulse wave detected by the pulse wave sensor 18 becomes extremely small during the shock state. Therefore, in step S11, the difference between the average value of the amplitude value of the pressure pulse wave and the average value of the amplitude value of the impedance pulse wave exceeds the allowable value α, and it is determined that the pressure pulse wave is abnormal, The blood pressure determination routine of step S12 is executed.

In the blood pressure determination routine, as shown in FIG.
In SR1, the count content T ₂ of the other timer that counts the pulse signal CK ₂ is reset and counting of the pulse signal CK ₂ is started. In the next step SR2, the differential amplifier 40
From this, it is determined whether or not the impedance pulse wave is detected, and the process is kept waiting until it is detected. If it is determined that the impedance pulse wave is detected, the following step SR3
Is executed and the detected impedance pulse wave M _I1 is
The maximum value m _Imax and the minimum value m _Imin are stored as well as stored in 70.

In step SR4, the blood pressure value is calculated based on the equations (1) and (2) from the previously obtained correspondence relationship between the impedance pulse wave and the pressure pulse wave as shown in the following equations (3) and (4), respectively. Are continuously determined. That is: m _Pmax = K ₁ · m _Imax (3) m _Pmin = K ₂ · m _Imin (4) However, since K ₁ and K ₂ are constants, these equations (3) and Step in equation (4)
By substituting the maximum value m _Imax and the minimum value m _Imin determined in SR3, the maximum value m _Pmax and the minimum value m _Pmax of the pressure pulse wave
_Pmin is _calculated, and the maximum value m _Pmax and the minimum value m _Pmin
By substituting in the above equations (1) and (2) respectively, the systolic blood pressure value SYS and the diastolic blood pressure value DIA are calculated. Then, by executing the next step SR5, the blood pressure value SYS determined in step SR4 and
DIA and the impedance pulse wave detected in step SR2 are displayed respectively.

Next, in step SR6, similarly to step S11, the impedance pulse wave is made to wait until N pieces are stored in the RAM 70, and the average value of the amplitude values of these N impedance pulse waves is set in the same manner. Whether or not the difference between the N amplitude values stored in the RAM 70 and the average value of the amplitude values of the pressure pulse wave exceeds the allowable value α, that is, whether the pressure pulse wave has recovered to a normal value. To be judged. If it is determined that the pressure pulse wave is normal, step S1 of the main routine shown in FIG.
4 and below are executed again, but if it is determined that the pressure pulse wave has not yet recovered to the normal state, the subsequent step SR7 is executed, and the counting content T ₂ of the other timer is predetermined. It is determined whether or not the count content T ₀ ′ has been reached. This count content T ₀ ′ corresponds to the time interval for correcting the correspondence relationship determined in step S13 when it is determined that the pressure pulse wave is abnormal, and is used to recover the living body from the shock state. It is set for a relatively long time that is expected to take. Therefore, when the count content T ₂ reaches T ₀ ′, steps S3 and subsequent steps are executed again, but since T ₀ ′ has not yet been reached at this stage,
SR2 and below are executed and a series of impedance pulse waves M ₁₂ , M
Each time ₁₃ ... is detected after execution of step SR6, the systolic blood pressure value SYS and the diastolic blood pressure value DIA are determined, and these blood pressure values are continuously displayed on the blood pressure value display 78, and the impedance is The pulse wave shape is continuously displayed on the waveform display 88. If the determination in step SR7 is affirmative in the process of repeatedly performing the operations in step SR2 and subsequent steps as described above, steps S3 and subsequent steps in the main routine are executed again to find the correspondence relationship between the pressure pulse wave and the blood pressure value. To be fixed.

As described above, in the pulse wave monitoring device of the present embodiment, in the state where the pressure pulse wave is normally detected from the pulse wave sensor 18, the pressure pulse wave shape is displayed on the waveform display 88, and in advance. From the correspondence between the obtained pressure pulse wave and blood pressure value,
Although the systolic blood pressure value SYS and the diastolic blood pressure value DIA are determined based on the actual blood pressure values H and L determined based on the pulse wave detected by the pressure of the living body by the cuff 52 and the pressure pulse wave, respectively. If the pressure pulse wave detected from the pulse wave sensor 18 is determined to be abnormal in step S11 due to, for example, falling into a shock state, the step
The impedance pulse wave detected from the operational amplifier 40 in the blood pressure determination routine of S12 is displayed on the waveform display 88, and based on the impedance pulse wave, the blood pressure value is continuous from the correspondence relationship between the blood pressure value and the pressure pulse wave. It is decided. Therefore, according to the present embodiment, when an abnormality occurs in the pressure pulse wave, the impedance pulse wave in which the pulsation is relatively clear is detected and displayed even in the shock state of the living body, so that the accurate pulse is always obtained. It is possible to obtain the effect that the wave display is performed and the heartbeat can be accurately grasped.

Hereinafter, another embodiment of the present invention will be described with reference to the drawings. In this embodiment, the same parts as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 9 is a flow chart showing a part of the operation of the present embodiment, which is a subroutine that is executed at predetermined intervals in the course of repeatedly executing the main routine shown in FIG. In step ST1, the latest pressure pulse wave detected by the pulse wave sensor 18 is read, and in step ST2, the latest impedance pulse wave detected by the differential amplifier 40 is read. next,
When step ST3 is executed, the peripheral vascular resistance is calculated from the relationship shown in the following expression (5).

(A _P / A _I ) ・ K ₃ ∝R ・ ・ ・ (5) where A _P : amplitude value of pressure pulse wave A _I : amplitude value of impedance pulse wave K ₃ : predetermined constant R: peripheral blood vessel Resistance Then, step ST4 is executed, and the calculated peripheral blood vessel resistance is additionally displayed on the blood pressure display 78 or the waveform display 88, or displayed on a separately provided display. By doing this, peripheral vascular resistance can be detected relatively easily without providing a special device,
There is an advantage that information about a living body can be obtained in more detail. An embodiment of the present invention has been described above with reference to the drawings, but the present invention can be suitably implemented in other modes.

In the above-described embodiment, the abnormality of the pressure pulse wave when the amplitude of the pressure pulse wave becomes extremely small due to the shock state of the living body, for example, is detected. By adopting the standard, the pressure pulse wave abnormality occurring in different situations may be detected. For example, the change direction of the pressure pulse wave detected this time from the previous pressure pulse wave is compared with the change direction of the impedance pulse wave detected this time from the previous impedance pulse wave, and these change directions do not match. In this case, it is determined that the pressure pulse wave has been abnormally detected due to the displacement of the device of the pulse wave sensor 18 or the change in the peripheral blood flow resistance.

Further, in the above-described embodiment, a step for detecting abnormality of the impedance pulse wave may be provided. For example,
If the electrodes 36, 38 or the electrodes 44, 46 fixed to the living body are removed, or if any abnormality occurs in the living body itself,
The impedance pulse wave is disturbed or the pulse wave becomes abnormally small due to the influence of external noise.
In order to detect the abnormality of the impedance pulse wave,
In the blood pressure determination routine shown in the figure, for example, an abnormality determination step is inserted after step SR2 so that the amplitude of the impedance pulse wave and the magnitude from the baseline (for example, the zero volt line) to the peak value of the impedance pulse wave can be measured in a unit time (for example, 5 50) or more within 50 seconds, or when the impedance pulse wave generation time is 30 times longer than the normal generation cycle, for example.
When it deviates by more than%, it is judged as abnormal. If this determination is affirmative, steps S3 and subsequent steps of the main routine are executed again, the correspondence between the actual blood pressure values H and L and the pressure pulse wave is obtained again, and the pressure pulse wave is abnormal. It is determined whether or not.

Further, in the above-mentioned embodiment, the pulse wave was taken from the artery 12 which is a radial artery located on the radial bone near the wrist of the living body, but the pulse wave is located relatively close to the epidermis of the living body. It may be collected from other arteries which are easy to collect, such as carotid artery and dorsalis pedis artery.

If the pressure pulse wave detected by the pulse wave sensor 18 is determined to be abnormal by controlling the CPU 30 by connecting an alarm device or the like, the alarm device displays an alarm with an alarm sound or the like. It may be so arranged that the measurer or the like is informed of the abnormality of the pressure pulse wave detection.

Further, in the pulse wave monitoring device of the above-described embodiment, based on the correspondence between the pressure pulse wave detected by the pulse wave sensor 18 and the actual blood pressure values H and L detected by the compression of the cuff 52. Although the blood pressure value was continuously determined and displayed, such blood pressure measurement and display need not be performed in particular, and therefore, the steps for blood pressure measurement / display operation,
And the components such as the cuff 52 and the blood pressure indicator 78 required for it can be omitted.

Further, in the above-described embodiment, the cuff 52 is the pulse wave sensor 18
Although it is attached to the other arm from the one to which the is attached, it can be attached to the same arm as the pulse wave sensor 18.

Furthermore, in the above-mentioned embodiment, the so-called oscillometric method for determining the blood pressure value based on the change in the magnitude of the pulse wave generated by changing the compression pressure on the living body of the cuff 52 is adopted as the blood pressure measuring method. However, instead of this, a microphone method or an ultrasonic method that determines the blood pressure value based on the occurrence and disappearance of the pulse sound generated in the cuff 52 in the process of changing the compression pressure of the cuff 52 is adopted. Is also good. Further, the blood pressure value may be determined based on the pulse wave generated in the cuff 52 during the depressurizing and boosting period.

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 illustrating the configuration of a pulse wave monitoring device that is an embodiment of the present invention. FIG. 2 is a front sectional view showing the configuration of the pulse wave sensor of FIG. 1 in detail. FIGS. 3 (a) and 3 (b) are time charts showing changes in pressure in the housing of the pulse wave detection probe of FIG. 1 and changes in the magnitude of the pressure pulse wave detected by the pulse wave sensor, respectively, over time. It is a chart. FIG. 4 is a diagram showing an example of a trend of the blood pressure value displayed on the blood pressure display in FIG. FIG. 5 shows the first
It is a figure which shows an example of the waveform displayed on the waveform indicator in a figure. FIG. 6 is a flow chart for explaining the operation of the apparatus shown in FIG. FIG. 7 and FIG. 8 are flowcharts for explaining a part of the operation of FIG. 6 in detail. FIG. 9 is a flow chart for explaining a part of the operation of another embodiment of the present invention. 12: Artery 18: Pulse wave sensor (pressure pulse wave detection means) 30: CPU 36, 38: Electrode 40: Differential amplifier (impedance pulse wave detection means) 70: RAM, 42: ROM 88: Waveform display (display) )

Claims (1)

(57) [Claims] 1. A pulse wave monitoring device for continuously monitoring a pulse wave of a living body, the pulse wave being obtained and continuously displayed on a display, the electrode being attached to the epidermis of the living body. Provided, continuously detecting the impedance in the portion where the electrode is attached,
Impedance pulse wave detection means for generating an impedance pulse wave signal representing the impedance, and detecting a pressure pulse wave generated in the artery by being pressed by the artery of the living body, and generating a pressure pulse wave signal representing the pressure pulse wave. The pressure pulse wave detection means for causing the pressure pulse wave detection means to constantly display the pressure pulse wave detected by the pressure pulse wave detection means, but when the pressure pulse wave detection by the pressure pulse wave detection means becomes abnormal, A pulse wave monitoring device comprising: a control unit that displays the impedance pulse wave detected by the impedance pulse wave detecting unit in place of the pressure pulse wave.