JP3533121B2 - Non-invasive continuous sphygmomanometer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-invasive continuous sphygmomanometer, and more particularly to continuous blood pressure by applying weak vibration to a blood vessel in a living body and detecting and analyzing the vibration propagating in the blood vessel. The present invention relates to a non-invasive continuous blood pressure monitor.

[0002]

2. Description of the Related Art Conventionally, as a non-invasive and continuous method for measuring blood pressure, a method disclosed in Japanese Patent Publication No. 9-506024 is known. This is to calculate the elasticity of the blood vessel by detecting the propagation velocity of the signal in the blood vessel by utilizing the fact that the elasticity of the blood vessel changes according to the change in blood pressure.
The blood pressure is estimated from the elasticity of the blood vessel. The outline of the processing is as follows.

A blood vessel is vibrated from the body surface of a subject, and the vibration propagated on the blood vessel is detected. After converting the detected vibration into a digital signal, filtering processing and phase detection processing are performed. The phase-detected signal is I (real number) component and Q
(Imaginary number) component is separated. At this time, theoretically,
The detected signal plotted on the IQ plane draws an arc centering on a certain point, and the point on the arc seen from this center point, that is, the detected signal on the IQ plane The change in position is the change in vibration propagation velocity due to blood pressure fluctuation. The change in vibration propagation velocity represents a change in blood vessel elasticity, and the change in blood vessel elasticity represents a change in blood pressure, that is, dynamic pressure.

In the invention disclosed in Japanese Patent Publication No. 9-506024, the relative change of the blood pressure value is calculated by estimating the center point of the arc formed on the IQ plane by the detected signal. I have to. By calibrating this relative change with the measurement values of the systolic blood pressure and the diastolic blood pressure, which are separately set for the same subject, the blood pressure in the living body is measured non-invasively and continuously. The measured blood pressure waveform is displayed along with biological information waveforms such as an electrocardiogram, a respiratory curve, and oxygen saturation while sweeping on the same monitor.

[0005]

However, in the invention disclosed in Japanese Patent Publication No. 9-506024, the vibration frequency of the vibration exciter that operates well is in the human audible range, and the vibration amplitude is large. In this case, the operator and the subject may be uncomfortable. Especially, the vibration frequency is 1000
The tendency becomes stronger as the frequency becomes higher than Hz. In addition, when the vibration amplitude is large, there is a problem that the power consumption of the device increases, while on the other hand, when the vibration amplitude is too small and the vibration frequency is not appropriate, it is possible to perform blood pressure measurement correctly. There was a problem that I could not.

The present invention determines the range in which blood pressure can be measured, and adjusts the vibration amplitude or frequency of the vibration exciter manually or automatically according to the range, thereby making the operator or subject uncomfortable. And a power-saving non-invasive continuous blood pressure monitor.

[0007]

A non-invasive continuous blood pressure monitor according to the present invention comprises a vibrating means for vibrating a blood vessel, a vibration detecting means for detecting a vibration propagating through the blood vessel, and a vibration detecting means for detecting the vibration. Phase detecting means for phase detecting an electric signal obtained from the vibration, blood pressure calculating means for continuously and non-invasively measuring the blood pressure of the human body by analyzing the phase detected signal, and the vibrating means The vibration amplitude adjusting means for adjusting the vibration amplitude and the vibration frequency adjusting means for adjusting the vibration frequency of the vibration means are provided.
With this configuration, since the excitation amplitude and the excitation frequency can be adjusted within a range where blood pressure can be measured, blood pressure can be measured with a smaller excitation amplitude,
It is possible to reduce the discomfort of the operator and the subject and realize a power-saving non-invasive continuous blood pressure monitor.

In the non-invasive continuous sphygmomanometer according to the present invention, the blood pressure calculating means obtains a signal / noise ratio of the electric signal obtained by the vibration detecting means, and the non-invasive continuous sphygmomanometer further comprises the phase detection. Determining means for determining whether or not the blood pressure measurement can be correctly performed based on the phase detection signal obtained by the means and the signal / noise ratio, and the determination means for determining that the blood pressure measurement cannot be correctly performed In this case, it has a configuration including an informing unit for informing the operator. With this configuration, the fact that the blood pressure measurement cannot be performed correctly is informed, so that the operator can recognize it and always perform the blood pressure measurement correctly.

The non-invasive continuous sphygmomanometer according to the present invention is obtained from the vibrating means for giving vibration to the blood vessel, the vibration detecting means for detecting the vibration propagating through the blood vessel, and the vibration detected by the vibration detecting means. Phase detection means for phase-detecting an electric signal, and the blood pressure of the human body is continuously and non-invasively measured by analyzing the phase-detected signal, and a signal of the electric signal obtained by the vibration detection means / A blood pressure calculating means for obtaining a noise ratio, a judging means for judging whether or not the blood pressure can be correctly measured based on the phase detection signal obtained by the phase detecting means and the signal / noise ratio, and the blood pressure by the judging means. And a vibration amplitude automatic adjusting means for automatically selecting the minimum vibration amplitude within a range determined to be able to be measured correctly. With this configuration, the minimum vibration amplitude is automatically selected within the range determined to be able to correctly measure the blood pressure, so that the blood pressure measurement can always be automatically performed with the minimum vibration amplitude. Therefore, it is possible to reduce the discomfort of the operator and the subject and realize a power-saving non-invasive continuous blood pressure monitor.

The non-invasive continuous sphygmomanometer according to the present invention has a notifying means for notifying the operator when the judging means judges that the blood pressure cannot be correctly measured, and a vibration amplitude of the vibrating means. Exciting amplitude adjusting means for adjusting, and an exciting frequency adjusting means for adjusting the exciting frequency of the exciting means, knowing the state in which blood pressure measurement cannot be performed correctly by the notification of the informing means, It has a configuration for adjusting the vibration frequency. With this configuration, in addition to the automatic adjustment of the vibration amplitude, the vibration amplitude and the vibration frequency can be manually adjusted, so that the vibration amplitude and the vibration frequency are adjusted to appropriate values for blood pressure measurement. Therefore, the discomfort of the operator and the subject can be reduced, and a power-saving non-invasive continuous blood pressure monitor can be realized.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The first and second embodiments of the present invention will be described in detail below with reference to FIGS. First, the non-invasive continuous blood pressure monitor according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

FIG. 1 shows a state in which the non-invasive continuous blood pressure monitor according to the first embodiment of the present invention is mounted on the arm of a human body. In FIG. 1, a shaker 1 as a vibrating means induces vibration on an artery of a living body, and the vibration induced on the artery by the shaker 1 is a detector 2 as a vibration detecting means.
To detect. The measuring device 3 drives the vibration exciter 1 to calculate and display a continuous blood pressure value based on the signal obtained by the detector 2, and further sets the vibration amplitude and vibration frequency of the vibration exciter 1. Then, a part of the living body is pressed by the cuff band 4, and the cuff control unit 5 drives the cuff band 4 to measure the maximum, minimum, and average blood pressure in one heartbeat in a non-invasive manner.

Next, with reference to FIG. 2, the blood pressure calculation unit 24, which is one of the characteristic portions of the measuring apparatus shown in FIG. 1 particularly in the first embodiment, will be described. The blood pressure calculation unit 24
First, the vibration waveform Asin (2πft) of the frequency f is generated. Excitation waveform Asi generated by blood pressure calculation unit 24
n (2πft) is D / A converted by the D / A converter 23. The vibrator 1 induces the vibration waveform D / A converted by the D / A converter 23 on the blood vessel. The detector 2 detects the vibration that is induced by the vibrator 1 and propagates on the blood vessel wall. The vibration detected by the detector 2 is amplified by the amplification unit 21, A / D converted by the A / D conversion unit 22, and input to the blood pressure calculation unit 24 as blood pressure calculation means. The blood pressure calculation unit 24 obtains a continuous change in blood pressure from the input of the vibration signal detected by the detector 2. A specific processing procedure of the detection signal will be described.

First, the blood pressure calculation unit 24 performs a discrete Fourier transform process on the input vibration signal W (t),
The signal / noise ratio calculating unit of the blood pressure calculating unit 24 calculates the signal / noise ratio SN. Further, as shown in FIG. 3, the three-stage processing of steps S101 to S103 is executed. First, in step S101, the vibration signal W (t) is calculated by a method known as quadrature detection.
Phase detection is performed by the phase detection means in the blood pressure calculation unit 24,
Si (t) that is the real component (I component) of the phase change and Sq (t) that is the imaginary component (Q component) are calculated (t is the time).

Next, in step S102, the center point (Ci) of the arc formed on the IQ plane by the I component Si (t) and the Q component Sq (t) of the phase change obtained in step S101. , Cq) are estimated. Also, I component S
i (t), Q component Sq (t), and the center point of the arc (C
i, Cq) to calculate the radius r (t) of the circular arc by the following formula [Equation 1]
Ask from.

[0016]

[Equation 1]

In step S103, the angle θ (t) of the I component Si (t) and the Q component Sq (t) seen from the center point (Ci, Cq) of the arc as shown in FIG. It is calculated from the formula [Equation 2].

[0018]

[Equation 2]

This angle θ (t) represents a continuous change of the blood pressure value, and the angle θ (t) is measured by the cuff 4 and the cuff control unit 5 to obtain the maximum blood pressure value, the average blood pressure value and the minimum blood pressure value. The continuous blood pressure value p (t) is calculated by performing calibration using at least any two of these values (t is the time). The calculated continuous blood pressure value p (t) is swept and displayed as a time-series waveform on the blood pressure waveform display screen 51 of the measuring apparatus 3, as shown in FIG. The blood pressure waveform display screen 51 corresponds to the display unit 27 in FIG.

In FIG. 5, the vibration amplitude adjusting knob 52 corresponds to the vibration amplitude adjusting section 29 of FIG. 2. For example, when the vibration amplitude adjusting knob 52 is turned clockwise, the vibration amplitude A of the vibration exciter 1 increases. When it is turned counterclockwise, the vibration amplitude A of the vibration exciter 1 becomes smaller. Similarly, the vibration frequency adjusting knob 53 corresponds to the vibration frequency adjusting unit 28 in FIG. 2. For example, when the vibration frequency adjusting knob 53 is rotated clockwise, the vibration frequency f of the vibration exciter 1 increases, and counterclockwise. When turned, the vibration frequency f of the vibration exciter 1 becomes low. In this way, the vibration amplitude A and the vibration frequency f of the vibration exciter 1 are adjusted, and the loudness and height of the notification sound by the measurement state notification unit 26 are adjusted appropriately. The range of the excitation frequency f that can be set in the first embodiment of the present invention is approximately 50 Hz.
~ 2000 Hz.

The measurement state measuring section 25 determines whether or not the blood pressure can be correctly measured based on the calculated signal / noise ratio SN and the radius r (t) of the arc. When the signal / noise ratio SN is large, that is, when the ratio of the noise component in the input signal is small and the variation in the value of the radius r (t) of the circular arc is small, the measurement state measuring unit 25 correctly measures the blood pressure. Determine that Specifically, SN <Thresh SN Std r> Thresh Std When the condition of r 1 is satisfied, it is determined that the blood pressure measurement is being performed correctly.

In the above equation, Std r is the radius r (t) of the circular arc calculated during a certain time T, ..., r
Is the standard deviation of (t + T), and Thresh SN, T
hresh Std r is a threshold that can be set by the operator. If the measurement state measuring unit 25 determines that the blood pressure cannot be measured correctly, the measuring device 3
The buzzer 54 sounds. The buzzer 54 corresponds to the measurement state notification unit 26 in FIG.

In the non-invasive continuous blood pressure monitor of the first embodiment of the present invention, the buzzer is used as a means for realizing the measurement state informing unit 26, but as another form, the blood pressure waveform display screen 51. It is also possible to display characters and pictures on the display, and to use an LED or the like.

The non-invasive continuous sphygmomanometer according to the first embodiment of the present invention determines the range in which blood pressure can be measured, and based on the determination, the excitation amplitude adjustment knob 52 and the excitation frequency adjustment knob 53. Is adjusted to manually adjust the vibration amplitude and the vibration frequency of the vibration exciter 1, so that the discomfort of the operator and the subject can be reduced and the power consumption can be reduced. .

Next, a non-invasive continuous blood pressure monitor according to the second embodiment of the present invention will be described with reference to FIGS.

In FIGS. 6 and 7, those having the same numbers and the same names as those given in FIGS. 1 and 2 are as follows:
Since the functions are the same, the description is omitted. The measuring device 63 shown in FIGS. 6 to 8 drives the vibration exciter 1, calculates and displays a continuous blood pressure value based on the signal obtained by the detector 2, and further displays the vibration amplitude of the vibration exciter 1. Configured to adjust automatically.

As shown in FIG. 8, the measuring device 63 is provided with a vibration amplitude adjusting button 81. This corresponds to the vibration amplitude automatic adjustment unit 71 in FIG. 7, and when this button is pressed, the blood pressure calculation unit 24 gradually changes the vibration amplitude of the vibration exciter 1 within the range of Amin to Amax. Each time, the measurement state determination unit 25 determines whether or not the blood pressure can be correctly measured. In this way, the vibration amplitude automatic adjustment unit 71 sets the minimum vibration amplitude that can correctly measure blood pressure. Amin is the minimum value among the amplitudes that can be excited by the shaker 1, and Amax is the maximum value among the amplitudes that can be excited by the shaker 1.

As another embodiment of the present invention, both functions of the vibration amplitude manual adjustment function in the first embodiment and the vibration amplitude automatic adjustment function in the second embodiment are provided and appropriately provided. It is also possible to switch and use.

The non-invasive continuous sphygmomanometer according to the present embodiment determines the range in which blood pressure can be measured, and based on the determination, the excitation amplitude automatic adjustment unit 71 automatically adjusts the excitation amplitude of the exciter 1. By adjusting so that the excitation amplitude is too small to prevent correct blood pressure measurement, and by preventing the excitation amplitude from being too large to increase power consumption, Power consumption can be reduced.

[0030]

The present invention is configured as described above, and in particular, the range in which blood pressure can be measured is determined, and the excitation amplitude and the excitation frequency of the exciter are manually adjusted based on the determination. By doing so, it is possible to provide a non-invasive continuous sphygmomanometer that has an excellent effect of reducing the discomfort of the operator and the subject and reducing the power consumption.

The present invention is constructed as described above, and in particular,
Determine the range where blood pressure can be measured, and based on that determination,
By automatically adjusting the vibration amplitude of the vibration exciter, the condition that the vibration amplitude is too small to measure blood pressure correctly can be prevented, and the vibration amplitude is too large to reduce power consumption. It is possible to provide a non-invasive continuous sphygmomanometer having an excellent effect that the discomfort of the operator and the subject can be reduced and the power consumption can be reduced by preventing the increase. .

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a non-invasive continuous blood pressure monitor mounted on a living body according to a first embodiment of the present invention,

FIG. 2 is a block diagram showing the configuration of the measuring apparatus shown in FIG.

FIG. 3 is a flowchart illustrating a calculation processing procedure of a blood pressure calculation unit shown in FIG.

FIG. 4 is a diagram showing an angle θ (t) of Si (t) and Sq (t) viewed from a center point (Ci, Cq) of an arc calculated by a blood pressure calculation unit;

5 is a front view of the measuring device shown in FIGS. 1 and 2, FIG.

FIG. 6 is a diagram showing a configuration of a non-invasive continuous blood pressure monitor mounted on a living body according to a second embodiment of the present invention;

7 is a block diagram showing the configuration of the measuring apparatus shown in FIG.

8 is a front view of the measuring device shown in FIGS. 6 and 7. FIG.

[Explanation of symbols]

1 shaker 2 detector 3 Measuring device 4 cuff belt 5 cuff control unit 21 Amplifier 22 A / D converter 23 D / A converter 24 Blood pressure calculator 25 Measurement status determination unit 26 Measurement status notification unit 27 Display 28 Excitation frequency adjuster 29 Excitation amplitude adjuster 51 Blood pressure waveform display screen 52 Excitation amplitude adjustment knob 53 Excitation frequency adjustment knob 54 buzzer 63 Measuring device 71 Excitation amplitude automatic adjustment unit 81 Excitation amplitude adjustment button S101 Quadrature detection step S102 Arc center estimation step S103 Blood pressure change calculation step

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-11-318839 (JP, A) JP-A-2000-139861 (JP, A) JP-A-2000-107139 (JP, A) JP-A-9-506024 ( JP, A) Patent 2981208 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 5/02-5/03 A61B 8/00-8/12

Claims (4)

(57) [Claims] 1. A vibrating means for vibrating a blood vessel, a vibration detecting means for detecting the vibration propagating in the blood vessel, and a phase detecting means for phase-detecting an electric signal obtained from the vibration detected by the vibration detecting means. A blood pressure calculating means for continuously and non-invasively measuring the blood pressure of the human body by analyzing the phase-detected signal; a vibration amplitude adjusting means for adjusting the vibration amplitude of the vibration means; A non-invasive continuous sphygmomanometer, comprising: a vibration frequency adjusting means for adjusting a vibration frequency of the vibrating means. 2. The blood pressure calculating means obtains the signal / noise ratio of the electric signal obtained by the vibration detecting means, and the non-invasive blood pressure monitor further detects the phase detection signal obtained by the phase detecting means. Judgment means for judging whether or not the blood pressure measurement can be performed correctly based on the signal / noise ratio, and notifying means for notifying the operator when the judgment means determines that the blood pressure measurement cannot be performed correctly. The non-invasive continuous blood pressure monitor according to claim 1, further comprising: 3. A vibrating means for vibrating the blood vessel, a vibration detecting means for detecting the vibration propagating through the blood vessel, and a phase detecting means for phase detecting an electric signal obtained from the vibration detected by the vibration detecting means. And a blood pressure calculating means for continuously and non-invasively measuring the blood pressure of the human body by analyzing the phase-detected signal, and for obtaining a signal / noise ratio of the electric signal obtained by the vibration detecting means, Determination means for determining whether or not the blood pressure measurement can be correctly performed based on the phase detection signal obtained by the phase detection means and the signal / noise ratio; and a range determined by the determination means to be able to correctly perform the blood pressure measurement. A non-invasive continuous sphygmomanometer, which is provided with a vibration amplitude automatic adjusting means for automatically selecting the minimum vibration amplitude in the inside. 4. An informing means for informing an operator when the determination means determines that the blood pressure cannot be correctly measured, and an excitation amplitude adjusting means for adjusting an oscillation amplitude of the exciting means. A vibration frequency adjusting means for adjusting the vibration frequency of the vibration means is provided, and the vibration amplitude and the vibration frequency are adjusted by knowing that the blood pressure measurement cannot be correctly performed by the notification of the notification means. The non-invasive continuous blood pressure monitor according to claim 3, wherein