JPS61179131A - Blood non-observing type continuous hemomanomometer - 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] lf! TECHNICAL FIELD The present invention relates to a non-invasive continuous blood pressure monitor that continuously measures blood pressure non-invasively through a finger or the like.

[Prior art and its problems] Conventional non-invasive continuous blood pressure monitor (Special Publication No. 59-5296)
Then, external pressure is continuously applied using a cuff, etc., and servo control is performed so that the external pressure at the 71111 fixed site is the same as the arterial blood pressure.
The external pressure at that time was used as the blood pressure value, and N series A111 was performed. In this case, the measurement site was squeezed with the same pressure as the arterial blood pressure, causing congestion and physical pain. Furthermore, when measuring with a finger, the arterial blood pressure changes due to blood congestion, resulting in a fixed error. Therefore, at present, the measurement must be interrupted every 10 minutes to relieve the congestion, and there is a drawback that continuous measurement for a long time of 10 minutes or more is difficult.

``Object of the Invention'' The present invention has been made in view of the above-mentioned drawbacks of the prior art, and its purpose is to continuously measure the pressure outside the measurement site by keeping it lower than the arterial blood pressure. ,
To provide a non-invasive N-series sphygmomanometer which eliminates congestion and measurement errors caused by it, minimizes measurement site restriction, and enables stable measurement over a long period of time.

SUMMARY OF THE INVENTION] In order to achieve the above object, the non-invasive M-continuous blood pressure monitor of the present invention includes a cuff attached to a site to be measured, a pressure sensor that detects the internal pressure of the cuff, and a pressure sensor that increases or decreases the internal pressure of the cuff. a volume sensor inserted between the cuff and the measurement site to detect changes in intravascular volume that vary with pulsation of the blood vessel in the measurement site; and pressure control means based on the output of the volume sensor. The servo control means detects a cuff pressure (Pc) at which the volume pulse wave amplitude of the volumetric sensor output is maximum, and further detects a cuff pressure lower than the cuff pressure (Pc). (Pd) in the cuff, the average surface of the volume sensor output is set as the servo target (II), and the pressure control means sets the volume pulse wave amplitude to a minimum based on the volume sensor output signal. is servo-controlled, the cuff pressure (Ps) at which the volume pulse wave amplitude becomes less than a predetermined value is continuously detected, and the cuff pressure (Pd) is calculated from the cuff pressure (Ps) and the cuff pressure (Pc).
) is subtracted and the sum is used as the measured blood pressure value.

Also preferably, the cuff pressure (Pd) is a cuff pressure (Pc).
One aspect of this is that the pressure is lower than the constant pressure.

Preferably, the cuff pressure (Pd) is a cuff pressure at which the volume pulse wave amplitude becomes approximately 1/2 of the maximum value.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

According to the so-called volume compensation method, the pulsating intravascular volume is
External pressure is applied from outside the body to maintain the blood pressure (
Continuous measurement of blood pressure is possible by measuring the external pressure with the blood pressure (blood pressure) in equilibrium. The operating principle of the present invention is based on this volume compensation method, and it is possible to measure N-continuous blood pressure while keeping the extracorporeal pressure (cuff pressure) lower than in conventional methods.The principle is as follows. .

According to elasticity theory, the relational expression holds true if the incompressibility of the blood vessel wall is ignored. Here, R1 = Blood vessel inner diameter R2 Two blood vessel outer diameter V: Intravascular volume Vo: No-load intravascular volume Pb: Intravascular pressure Pc: External pressure (cuff pressure) E: Complex modulus of elasticity of blood vessel. Therefore, from equation (1), when VkVO, pb%P
c, and the conventional method is to detect the external pressure Pc at this time and obtain the intravascular pressure pb. It is il atonement law.

That is, a cuff pressure Pc of the same magnitude as the intravascular pressure pb was applied to cancel the intravascular pressure pb.

Now, if we set V = Vo + ΔVc, then equation (1) = I/K (Pb - Pc)
... (2)-', Pb=KΔVc+Pc
... (3), and K
ΔVc is the load applied to the blood vessel wall. Therefore, ΔV
pb can be measured continuously from c and Pc.

In this case, when the intravascular volume change ΔV is measured while applying the average external pressure Pc, ΔV shows the maximum value ΔVmaX at the time when the average external pressure n=average intravascular pressure 9, and the average intravascular volume V at this time is unloaded. It corresponds to the intravascular volume Vo. From this point on, if the average external pressure C is further reduced by C, the average intravascular volume V increases to 0+ΔVc. That is, Pb=Pc+ΔPc...(
When the relationship is 4), v=vo+Δvc +
+ The relationship (5) holds true. Therefore, equation (3) and (4
) by comparing the expression KΔvc':: li P
I can say C. Therefore, in this state, the change in intravascular volume V Δ
If the external pressure Pc is servo-controlled to cancel V, the intravascular result V is maintained at Vo+ΔVc, and if the external pressure (cuff pressure) Pc at this time is continuously measured, Pb=Pc+Δ
Blood pressure pb can be continuously measured from Pc.

1 to 3 relate to an embodiment of the present invention, and FIG. 1 is a block diagram showing a continuous blood pressure monitor of the embodiment. In the figure, l is a cuff adapted to the shape of the finger at the measurement site, 2 is a pressure sensor that detects the pressure inside the cuff, 3 is an LED that illuminates the arterial blood flow in the finger, and 4 is the reflection from the arterial blood flow. a phototransistor that detects light or transmitted light; 5 a volume sensor that detects intravascular volume changes from the output of the phototransistor 4;
6 is a tire flamm pump that servo controls the cuff internal pressure; 7
1 is a moving coil that servo drives the tire flamm pump 6; 8 is a coil driver that drives the moving coil 7; 9 is a roller pump that increases and decreases the internal pressure of the cuff at a constant speed; 10
is a tank that stores the liquid (water) to be filled into the cuff,
11 is a motor driver that drives the roller pump 9 at a constant speed;
12 is an A/D converter that digitally converts the pressure sensor signal PC and the volume sensor signal PG; 13 is a central processing unit (CPU) that realizes an example of the control of the present invention by executing the program of the embodiment in FIG. , 14 is the CPU
13 is a D/A converter that converts the control information of the output into an analog signal, and 15 is a D/A converter that converts the control information of the output into an analog signal;
a servo amplifier that performs servo control so that o+ΔVc);
16 is a phase compensation circuit for servo control, 17 is an automatic servo gain control circuit (AGC) that adjusts the servo gain to the crosspiece when the servo lubricant is activated/deactivated, and 18 is, for example, -
A liquid crystal display that continuously displays the systolic blood pressure SYS and diastolic blood pressure DIA for each beat; 19 is a liquid crystal display that adds an offset pressure correction value ΔPc to the detected cuff pressure PC to form an actual blood pressure signal (PC+ΔPc); The circuit 20 is a blood pressure signal terminal for outputting a signal to an external recording device or the like.

FIG. 2 is a timing chart showing operation signals of the embodiment. When you insert your finger inside the cuff, the inside of the cuff is filled with a certain amount of precursor, and pressure starts to be applied by driving the roller pump 11 under the control of CP013.
). In this state, the volume sensor 5 detects the intravascular swelling of the finger artery based on the output of the phototransistor 4 configured between the inner periphery of the cuff 1 and the inserted finger. Volume signal P of volume sensor 5 output
G is input to the CPU 13 via the A/D converter 12.
be monitored. Here, the pulse wave component PGa of the volume signal PG
The average cuff pressure Pcl at the time when c reaches its maximum (for example, t4) is the average external pressure (
= mean intravascular pressure).

The CPU 13 further reduces the cuff pressure from this state.

When the predetermined average cuff pressure Pc2 is reached, the roller pump control is changed to 1.
After that, servo control is activated to maintain the pulsating intravascular volume at the target value (ts).

As a method for determining the predetermined average cuff pressure Pc2, for example, one foot pressure may be subtracted from the cuff pressure (, PCl). In this way, a cuff pressure suitable for long-term continuous measurement can be easily selected. Alternatively, the cuff pressure at which the volume pulse wave amplitude becomes approximately 1/2 of the maximum value may be used. By doing this, a valid volume pulse wave signal can still be used for servo control.
Highly accurate and reliable blood pressure measurement is 0rtrt.

In any case, from this point on, the intravascular volume signal PG is guided to the terminal f of the servo amplifier 15, and the intravascular volume signal PG sent from the CPU 13 via the D/A converter 14 is sent to the first terminal. The servo target value (Vo+ΔVc) is input. As a result, the servo amplifier 15 moves once to eliminate the pulse wave component of the intravascular volume signal PG, and in combination with the actions of the phase compensation circuit 16 and the eye motion gain control circuit (AGC) 17, the blood vessel The internal volume is maintained at almost the target constant I(j (Vo+ ΔVC) (ts)
That is, from this point on, the equilibrium state of intravascular and extravascular pressures is maintained.

The cuff pressure signal PC output from the pressure sensor 2 is also read into the CPU 13 via the A/D converter 12 and monitored. The CPU 13 calculates the average external pressure P obtained at the timing of t4.
The difference ΔPc (=Pcl - Pc2) between the average external pressure Pc2 obtained at the timing of cl and ts is obtained (ts), and after t6 when the servo is achieved, the difference ΔPc is added to the cuff pressure signal PG for each beat to calculate the subject's Systolic blood pressure SYS and diastolic blood pressure DIAt are continuously displayed digitally. Also, the difference ΔP
By outputting c to the adding circuit 19, continuous blood pressure No. 48 is formed at the blood pressure signal terminal 20.

FIG. 3 is a flowchart showing the continuous blood pressure measurement control procedure of the embodiment. After inserting a finger into the cafe, measurement starts and the main process begins. In step S1, the roller pump 9 starts rapidly pressurizing the cafe (t.

). As a result, the intravascular volume signal P G b i rises, and at the same time, the volume pulse wave component PGac due to the digital artery pressure is superimposed (tl). In step S2, changes in the amplitude of this volume pulse wave component PGac are monitored. When the force is applied, the maximum amplitude (t2) of the volume wave component PGac appears, and as the pressure is applied further, the amplitude gradually decreases. In step S3, the amplitude of the volume pulse wave component is about 172, which is the maximum value.
When the determination is satisfied, the sudden pressurization is stopped at IF, and low iR pressure (e.g. -3lllmHg/
5ec) (t3). In step S5, changes in the volume pulse wave component PGac are further monitored. Then, due to the decrease in external pressure, the maximum point of the amplitude of the first volume wave appears again (
t4). As described above, the average intracuff pressure Pc1 at this moment can be considered to be equal to the average intravascular pressure pb. Further, as described above, the average intravascular volume V1 at this time can also be regarded as the unloaded coplanar intravascular volume Vo. When the maximum point of the volume pulse wave amplitude is detected in step S6, step S
7, the average usage at that time is stored in the memory (not shown) of the CPU 13. In step S8, the amplitude 11fi change of the volume pulse wave component PGac is further monitored under cuff decompression, and in step S9, the amplitude is approximately 1/2 of its maximum value.
wait until it becomes Eventually, when the determination in step S9 is satisfied, the process proceeds to step S10, where the roller pump 9 is stopped and the average cuff pressure is maintained at the current cuff pressure Pc2.

Regarding this point, a method of detecting a point where the pressure is further reduced to a constant pressure (for example, -30 mmHg) from the average cuff pressure port may be used.

In step Sll, the decrease ΔPc in the average cuff pressure and the corresponding increase ΔVc in the intravascular volume are determined and stored in the memory. In step S12, the servo target value V2=Vo+ΔVc of the intravascular volume signal PG is output to the positive input terminal of the servo amplifier 15, and in step 313, the AGC 17 is biased +'T to form a servo loose. Also step S
At L4, the blood pressure correction value ΔPc is output to the adding circuit 19 to enable the formation of a blood pressure signal. In step 515, the amplitude change of the volume pulse wave component PGac is monitored again. In this state, the servo loop works to cancel the volume pulse wave signal based on the volume pulse wave signal. That is, the pulse wave amplitude gradually decreases and the servo drive is performed via the tire flamm pump 6 so that the intravascular volume becomes a constant value (Vo+ΔVc). In step S16, the process waits until the volume pulse wave signal amplitude becomes within a certain value (approximately O). Eventually, when the determination in step 516 is satisfied (t6), the process advances to step S17 and step 318, and the display unit 18 displays the systolic blood pressure SYS (= Pcmax + △
Pc) and diastolic blood pressure DIA (= Pcm1n + Δ
Pc) is displayed. In step S19, it is determined whether there is an external instruction to end the measurement (not shown). If there is no instruction, the process returns to step 515, and the blood pressure display for each beat is repeated in the same manner as described above. If there is a termination instruction, the process proceeds to step S20, where the AGC 17 is deenergized, and further step S2
1, the cuff 1 is rapidly decompressed by the roller pump 9.

The device of the embodiment described above can be applied to the central blood pressure measurement using the finger, the north arm, the wrist, or other locations.

[Effect of the Invention 1] As explained above, according to the present invention, a-continuous blood pressure measurement is performed by tightening the M1 foot region with a pressure lower than the arterial blood pressure, thereby reducing congestion and measurement errors caused by it. The restraint of the probe part is kept to a minimum.
It has the effect of allowing stable non-invasive long-term continuous blood pressure measurement.

[Brief explanation of the drawing]

Fig. 1 is a block configuration diagram showing a continuous blood pressure monitor according to an embodiment of the present invention, Fig. 2 is a timing chart showing operation signals of the embodiment, and Fig. 7JIj3 is a flowchart showing a continuous blood pressure measurement control procedure of an embodiment. be. Here, l...cuff, 2...pressure sensor, 3...
LED, 4... Phototransistor, 5... Volume sensor, 6... Tire flamm bomb, 7... Moving coil, 8...-Coil dry/to, 9... Roller pump, 10...・Tank, 11...Motor driver,
12... A/D converter, 13... Central processing unit (CPU), 14... D/A converter, 15... Servo amplifier, 16... Phase N18 circuit, 17. ...Automatic servo gain control circuit (AGC), 18
. . . Liquid crystal display, 19 . . . Addition circuit, 20 . . . Blood pressure signal terminal.

Claims (3)

[Claims] (1) A cuff to be attached to the part to be measured, a pressure sensor for detecting the internal pressure of the cuff, a pressure control means for increasing and decreasing the internal pressure of the cuff, and a cuff to be inserted between the cuff and the part to be measured, and a pressure sensor for detecting the internal pressure of the cuff. The servo control means includes a volume sensor that detects a change in intravascular volume that changes with the pulsation of the blood vessel, and a servo control means that servo controls the pressure control means based on the output of the volume sensor, and the servo control means controls the output of the volume sensor. Detect the cuff pressure (Pc) at which the volume pulse wave amplitude is maximum,
Further, with a cuff pressure (Pd) lower than the cuff pressure (Pc) being applied to the cuff, the average value of the volume sensor output is set as a servo target value, and the volume pulse wave amplitude is determined based on the volume sensor output signal. The pressure control means is servo-controlled so that the volume pulse wave amplitude becomes a predetermined value or less, and the cuff pressure (Ps) is continuously detected, and the cuff pressure (Ps) and the cuff pressure are A non-invasive continuous sphygmomanometer characterized in that the measured blood pressure value is the sum of the value obtained by subtracting the cuff pressure (Pd) from the pressure (Pc). (2) The non-invasive continuous sphygmomanometer according to claim 1, wherein the cuff pressure (Pd) is a constant pressure subtracted from the cuff pressure (Pc). (3) Cuff pressure (Pd) is approximately 1 when the volume pulse wave amplitude is at its maximum value.
2. The non-invasive continuous blood pressure monitor according to claim 1, wherein the cuff pressure is /2.