JP3223415B2 - Electronic sphygmomanometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic sphygmomanometer characterized by blood pressure determination.

[0002]

2. Description of the Related Art A method of non-invasively measuring blood pressure using a cuff has been generally used. As a non-invasive electronic sphygmomanometer, for example, a cuff is attached to a living body part, the air pressure in the cuff is pressurized by a pump or the like, and gradually increased until the artery stops bleeding. Alternatively, in a gradual decompression process after rapid pressurization, the waveform information of the pulse wave in the blood vessel is extracted, while the pressure sensor detects the cuff pressure in each change process, and a predetermined waveform parameter is extracted from the extracted waveform information. In some cases, a blood pressure value such as a systolic blood pressure or a diastolic blood pressure is determined from the cuff pressure corresponding to the waveform parameter.

[0003]

In non-invasive blood pressure measurement, blood vessels are hardened during the process of gradually increasing the pressure of the measurement cuff to close the blood vessel or to resume the blood flow by gradually reducing the pressure after the cuff is pressurized. Affected. For example, when the systolic blood pressure is exceeded during the gradual pressurization process, the blood vessel is closed. However, if there is an increase in blood vessel hardness due to arteriosclerosis or aging, a pressure higher than the pressure (systolic blood pressure) originally required to close the blood vessel is required, and it is necessary to determine a blood pressure higher than the arterial blood pressure measured by the direct method. The following problems occur. Further, in the blood pressure measurement on the distal side from the upper arm, in addition to the effect of the blood vessel hardness, due to the effect of contraction of the peripheral blood vessels due to narrowing and obstruction of the blood vessel diameter due to the progress of arteriosclerosis, cold or stress, etc.
A blood pressure measurement error may occur with the upper arm blood pressure value.

[0004] The present invention provides a method for determining a reliable arterial blood pressure value in a non-invasive blood pressure measurement and a blood pressure measurement on the distal side of the upper arm by using arterial stiffness, aging , and the like based on extracted pulse wave waveform information . And blood vessels due to climate, stress, load, etc.
Detecting a change in, eliminating blood pressure measurement error between the upper arm value in their blood pressure measurement error in non-invasive blood pressure measurement using, and blood pressure measurement in peripheral side of the upper arm.

[0005]

According to the first aspect of the present invention, there is provided:
The electronic sphygmomanometer has a cuff for compressing an artery, a cuff pressure detecting means for detecting a pressure in the cuff, and pulse wave waveform information for detecting pulse wave waveform information in a process of pressurizing or depressing the cuff. a detecting means, in which comprises a waveform parameter extraction means for extracting a predetermined waveform parameters from the detected waveform information, and blood pressure determining means for determining a blood pressure based on the extracted parameters and the detected cuff pressure, to the pulse Wave
The pulse waveform information detected by the shape information detecting means is based on the pulse waveform base.
Of the sharpness of the part (when the flatness of the base of the pulse wave disappears)
Point), and the pressure side sufficiently lower than the diastolic blood pressure (blood vessels
Uncompressed state) and the waveform parameter
The parameter extracted by the meter extracting means is the minimum blood pressure.
On the lower pressure side (in a state where blood vessels are not compressed)
The sharpness is determined by the maximum value of the sharpness of the pulse waveform base (the pulse waveform base).
Divided by the sharpness at the time when the flatness of the part disappears)
It is characterized by that. The electronic blood pressure according to claim 2.
The meter measures the cuff to compress the artery and the pressure inside the cuff.
Cuff pressure detection means to output and cuff pressurization process or decompression
In the process, a pulse wave waveform information detector that detects the pulse wave waveform information
And a predetermined waveform parameter is extracted from the detected waveform information.
Extracted waveform parameter extraction means and extracted parameters
Blood pressure to determine blood pressure based on and cuff pressure detected
Means for detecting the pulse wave waveform information
The pulse wave waveform information detected by the
In the separated pulse wave, the absolute value of the first positive inflection point is large.
And the magnitude of the absolute value of the first negative inflection point, and the second
The magnitude of the absolute value of the inflection point on the negative side
The parameter extracted by the parameter extracting means is
The magnitude of the absolute value of the inflection point on the negative side of
The value obtained by dividing the absolute value of the curved point by the magnitude of the second negative
The magnitude of the absolute value of the inflection point on the positive side is calculated as the inflection point on the first positive side.
Is the value divided by the magnitude of the absolute value of
You.

[0006]

Embodiments of the present invention will be described below. First, the features of this embodiment will be briefly summarized.
As shown in FIG. 8, the volume pulse wave obtained in the cuff pressurizing process or the depressurizing process in the non-invasive blood pressure measurement using a cuff or the like is based on the change in the arterial pressure (pressure wave), as shown in FIG. It is extracted reflecting the characteristics. A change in blood vessel hardness and a state of blood circulation can be detected from the waveform information of the pulse wave reflecting the characteristics of the blood vessel. Therefore, the present invention provides a pulse wave base that is not affected by pulse pressure and can characteristically capture the characteristics of blood vessels, a rising part of a pulse wave that corresponds to a rise in pressure associated with systolic blood ejection, and a peripheral part. Attention was paid to the re-rising pressure wave part generated by the reflected pressure wave from. For the former, the maximum value of the sharpness of the pulse waveform base (the sharpness at the time when the flatness of the pulse waveform base disappears) is A, and the sharpness on the sufficiently low pressure side (the state where the blood vessel is not compressed) than the diastolic blood pressure. Degree B, ratio B
/ A as a parameter (FIG. 5). When the blood vessel is hard, the volume fluctuation of the blood vessel due to the change in the arterial pressure at a pressure sufficiently lower than the diastolic blood pressure is small, and the volume pulse wave is distorted to reduce B, and as a result, B / A decreases. The latter used a pulse wave obtained by secondarily differentiating the volume pulse wave waveform in order to clarify the feature amount of the pulse wave. The magnitude of the absolute value of the first inflection point on the positive side is a, the magnitude of the absolute value of the first inflection point on the negative side is b, and the magnitude of the absolute value of the second inflection point on the negative side Is d, and b / a and d / a are parameters (FIG. 7). If the blood vessels become harder or the blood vessel diameter narrows due to pulse wave stiffening, aging, or vasoconstriction, and blood circulation worsens, the volume pulse wave becomes dull and a becomes smaller, so the parameter b / a becomes larger. Also, when the reflected pressure wave d from the periphery increases due to an increase in the peripheral resistance, etc.,
The parameter d / a increases. Generally, it has been reported in many papers and conferences that the second-order differentiated pulse wave is correlated with age. In addition, B / A and b /
a and d / a were well correlated with changes in blood pressure.

The details will be described below. FIG. 1 is a block diagram showing a hardware configuration of an electronic blood pressure monitor according to an embodiment of the present invention. The electronic sphygmomanometer, rises with pressing an artery (for example, a finger of the artery), a cuff 1 for internal vascular volume sensor 15 in the light-emitting element LED and made of light-receiving elements PT _r, to pressurize the cuff 1 (internal air pressure Drive) a pressure pump 2, a semiconductor pressure sensor 3 that detects the air pressure of the cuff 1 and converts it into an electric signal, a differential amplifier 4 that amplifies an output signal of the semiconductor pressure sensor 3, and drives a light emitting element LED. bandpass filter 6 for outputting the LED driving circuit 5, the light receiving signal of the light receiving element PT _r, only the pulse wave component for
An amplifier 7 for amplifying the output signal, and an A / D for converting a cuff air pressure signal (cuff pressure) output from the differential amplifier 4 by switching or a pulse wave signal output from the amplifier 7 to a digital signal. A converter 8, a quick exhaust valve 9 for releasing the cuff 1 to the atmosphere and rapidly reducing the air pressure of the cuff 1, a pressurizing pump 2, an LED driving circuit 5, an A / D
The converter 8 and the quick exhaust valve 9 are controlled, and the pulse wave component is chronologically acquired in the course of the change of the cuff pressure, and the processing for determining the blood pressure such as the systolic blood pressure and the diastolic blood pressure from the obtained cuff pressure is executed. And a display 11 for displaying the obtained blood pressure value, a power supply circuit 12, a power switch 13, and a start switch 14. However, the hardware configuration of this electronic sphygmomanometer is a general one and is not a feature of the present invention.

A feature of the present invention resides in a blood pressure determination processing method described below. Next, this point, that is, a blood pressure determination processing method in the electronic sphygmomanometer according to the present embodiment will be described with reference to flowcharts shown in FIGS. 2, 3, and 4. With the power switch 13 turned on, the start switch 1
When the switch 4 is turned on, the pressurizing pump 2 is turned on, and the cuff 1 is pressurized until the cuff pressure reaches a predetermined value. Then, pressurizing pump 2
Is turned off, and the cuff pressure is gradually reduced [Step S
T1]. For the gradual decompression, the rapid exhaust valve 9 may have its function coexisting, or a slow exhaust valve may be provided separately.

In the gradual decompression process, the pulse wave component W _f (t) is extracted (ST2), and every time data for one beat is obtained,
Calculating a pulse wave amplitude _{A mp (t) (ST3)} , the pulse wave amplitude A _mp
For each calculation of (t), the corresponding cuff pressure P (t) at that time
Is read and stored (ST4). Further, as shown in FIG. 6, the sharpness ΔV (t) of the base of the pulse wave waveform is calculated from the slope of the pulse wave before a predetermined time (ΔT) from the rise of the pulse wave (ST5). Also, the first waveform information parameter P _ar 1
(T) is calculated (ST6). This calculation formula is, as shown in the figure, P _ar 1 (t) = b / a, d / a. This calculation process will be described later in detail. When the processing of ST6 is completed, it is determined whether or not the blood pressure can be determined, that is, whether or not data necessary for calculation has been obtained (ST7), and the process returns to ST2 until the blood pressure can be determined, and ST2,.
The process of ST7 is repeated. When the blood pressure can be determined in ST7, a second waveform information parameter _Par2 is calculated (ST8). This calculation formula is, as described with reference to FIG.
_ar 2 = B / A. This calculation process will be described later in detail.

When the first waveform information parameter P _ar 1 (t) or the second waveform information parameter P _ar 2 is obtained,
A blood pressure calculation process is performed using these parameters (ST
9) The blood pressure is displayed on the display 11 (ST10), the air is rapidly exhausted (ST11), and the measurement is terminated. In the blood pressure calculation process in ST9, as shown in FIG. 5, the cuff pressure PCs corresponding to the point in time when the pulse wave component is first detected in the decompression process.
Is the systolic blood pressure, and the cuff pressure PCd at the time when the flat portion of the pulse wave waveform base disappears (the maximum value of the sharpness) is set to the diastolic blood pressure (Japanese Unexamined Patent Application Publication No.
Provisionally determined that these PCs, P
Cd and waveform information parameters B / A, b / a , d / a are
Coefficients α1, α statistically obtained in advance from data of multiple people
2, β1, β2, γ1, γ2 and constants δ1, δ2 Final determined systolic blood pressure SYS = PCs + (α1 * B / A) + (β1 * b / a) + (γ1 * d / a) + δ1, Final determined The diastolic blood pressure DIA = PCd + (α2 * B / A) + (β2 * b / a) + (γ2 * d / a) + δ2 is calculated. Here, (α1 * B / A) + (β1 * b / a) + (γ1 * d / a) + δ1 and (α2 * B / A) + (β2 * b / a) + (γ2 * d / a ) + Δ2 is for correcting the blood pressure value .

In the calculation of the first waveform information parameter P _ar 1 (t) in ST6, when entering ST6, the pulse wave W _f (t) for one beat obtained in ST2 is secondarily differentiated (for example, FIG. 7). This is stored as dW _f (t) (ST61). Next, the first peak on the positive side of dW _f (t) obtained in ST61 is detected and stored as a (ST6).
2). Subsequently, the first negative peak of dW _f is detected,
b (ST63). Similarly, the second peak on the negative side of dW _f is detected and stored as d (ST6).
4). From the thus obtained a, b, and d, b / a,
d / a is stored as the first parameter P _ar 1 (t).

Next, the calculation of the second waveform information parameter P _ar 2 in ST8 will be described. In step ST8, first, the minimum blood pressure, that is, the flattening of the pulse wave
The maximum value that is V (t) is stored as A (ST81),
Next, ΔV (t) at a pressure sufficiently lower than the diastolic blood pressure (for example, at the time when the pressure drops by 30 mmHg) is stored as B (ST8).
2), these A, stores the ratio B / A of B as the second waveform information parameters P _ar 2 (ST83).

In the electronic sphygmomanometer shown in FIG. 1, the cuff pressure at the time when a plethysmogram was generated during the gradual decompression process was set as the systolic blood pressure. FIG. 9 shows the correlation coefficient (R) between auscultation and finger blood pressure and the standard deviation (SD) of the error after using this parameter. Here, the error is (finger blood pressure value-auscultation value).

[0014] Thus, arteriosclerosis and aging, and more the degree of vasoconstriction due to load, stress, etc., the changes in the blood vessel by using the waveform information of the pulse wave, can reduce a measurement error factor by the blood pressure determined And improved accuracy.

[0015]

According to the present invention, the structure can be determined based on pulse wave waveform information, such as arteriosclerosis and aging , climate and stress.
Since captures changes in blood vessels by the load or the like to correct the blood pressure value, you can remove the measurement error factor in the blood pressure measurement using the cuff, to determine the reliable arterial blood pressure in non-invasive blood pressure determination method it can. Also, a highly reliable arterial blood pressure can be determined in blood pressure measurement on the peripheral side from the upper arm.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a hardware configuration of an electronic blood pressure monitor according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the overall operation of the electronic blood pressure monitor of the embodiment.

FIG. 3 is a flowchart illustrating a routine for calculating a waveform information parameter P _ar 1 in the flowchart.

FIG. 4 is a flowchart illustrating a calculation processing routine of a waveform information parameter P _ar 2 in the flowchart.

FIG. 5 is a diagram showing a change in cuff pressure, a change in blood vessel volume, and a sharpness of a plethysmogram in the course of relaxation from arterial compression by the cuff.

FIG. 6 is a diagram showing an original waveform of an extracted vascular plethysmogram.

FIG. 7 is a diagram showing a second derivative waveform of the extracted vascular plethysmogram.

FIG. 8 is a diagram illustrating a relationship between a pressure difference between a blood vessel and a volume pulse wave for detecting a pressure wave from the heart based on a volume characteristic of an artery.

FIG. 9 is a diagram showing a correlation coefficient between auscultation and finger blood pressure, and a standard deviation of an error.

[Explanation of symbols]

W _f (t) pulsation waveform dW _f (t) pulsation waveform of the secondary differential waveform a waveform dW _f (t) of the first positive peak b waveform dW first negative peak of the _f (t) d waveform dW _f ( t) 2nd negative peak ΔV (t) Sharpness of pulse wave waveform base A Maximum value of ΔV (t) B ΔV at sufficiently lower pressure (constant) than diastolic blood pressure
(T) value

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-319708 (JP, A) JP-A-7-246192 (JP, A) JP-A-6-296591 (JP, A) JP-A-1 195847 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 5/02-5/0295

Claims (2)

(57) [Claims] 1. A cuff for attaching to a predetermined part of a living body to compress an artery, a cuff pressure detecting means for detecting a pressure in the cuff, and a waveform of a pulse wave in a process of pressurizing or depressing the cuff. Pulse wave waveform information detecting means for detecting information, waveform parameter extracting means for extracting a predetermined waveform parameter from the detected waveform information, and blood pressure determining means for determining blood pressure based on the extracted parameters and the detected cuff pressure. In the electronic sphygmomanometer comprising, the pulse waveform information detected by the pulse waveform information detecting means,
The maximum value of the sharpness of the pulse waveform base (the flatness of the pulse waveform base is
Sharpness at the time of disappearance) and the pressure side sufficiently lower than the diastolic blood pressure
(In a state where blood vessels are not compressed)
The parameters extracted by the waveform parameter extracting means are
Low enough pressure than the diastolic blood pressure (the blood vessels are not compressed)
State) is defined as the maximum value of the sharpness of the pulse waveform base.
(Sharpness at the time when the flatness of the pulse waveform base disappeared)
Is a value Tsu, electronic blood pressure meter, characterized in that. 2. Attachment to a predetermined part of a living body to compress an artery
Cuff for detecting the pressure inside the cuff
Pulse waveform during step and cuff pressurization or depressurization
Pulse wave waveform information detecting means for detecting information, and a detected waveform
Waveform parameters that extract specified waveform parameters from information
Data extraction means, extracted parameters and detected cuff pressure
Blood pressure determining means for determining blood pressure based on the
In the child sphygmomanometer, the pulse wave waveform information detected by the pulse wave waveform information detecting means,
The first positive side of the pulse wave obtained by second derivative of the volume pulse wave waveform
And the absolute value of the inflection point of
The magnitude of the log value and the magnitude of the absolute value of the second negative inflection point
And the parameters extracted by the waveform parameter extracting means.
Parameter is the magnitude of the absolute value of the first negative inflection point.
Divided by the magnitude of the absolute value of the first inflection point on the positive side
And the magnitude of the absolute value of the second inflection point on the negative side
Is the value obtained by dividing the absolute value of the first positive inflection point.
An electronic sphygmomanometer characterized in that: