JPH0889485A - Blood pressure meter - Google Patents

Abstract

PURPOSE: To provide a blood pressure meter capable of accurately measuring average blood pressure and diastolic blood pressure by reducing variation of blood pressure by pulse wave height value fluctuation by obtaining a smooth continuous curve passing adjacency of a pulse wave height value. CONSTITUTION: Discrete wave height value data obtained together with increasing and decreasing cuff pressure detected by a pressure sensor 2 of this blood pressure meter and stored in RAM 13c are processed by CPU 13b with spline function and creates smooth continuous curve data passing adjacency of the discrete pulse wave height value. By this processing, variation of pulse wave height values can be reduced. Furthermore, diastolic blood pressure is measured by inflection points of the continuous curve data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blood pressure measuring device for measuring blood pressure from a continuous line connecting detected pulse wave peak values.

[0002]

2. Description of the Related Art Conventionally, a sphygmomanometer captures a pulse wave caused by a pulsation of an artery as, for example, vibration in a cuff, and measures systolic blood pressure, diastolic blood pressure, and average blood pressure based on this vibration. .

Various methods for measuring blood pressure with respect to changes in cuff pressure have been proposed. For example, Japanese Patent Laid-Open No. Sho 62
As disclosed in Japanese Patent Laid-Open No. 72317/1990, an “improved automated diastolic blood pressure monitor with data enhancement” is known. In this publication example, the detected pulse wave crest value that monotonically increases or decreases monotonically. It is used for the calculation, and the average value of the cuff pressure having the peak values of 69% and 55% of the maximum peak value is taken as the diastolic blood pressure required for blood pressure measurement.

[0004]

However, in the above-mentioned blood pressure measuring device of the conventional example, since the peak value of the detected pulse wave is monotonically increased or monotonically decreased, the peak value of the pulse wave is continuous. It is difficult to obtain a smooth continuous line that corrects the peak value and connects the peak values. Furthermore, in the above-mentioned conventional example, the diastolic blood pressure was empirically obtained such that the average value of the cuff pressure having the peak values of 69% and 55% of the maximum peak value is set as the diastolic blood pressure necessary for blood pressure measurement. In some cases, the blood pressure value of the diastolic blood pressure value cannot be accurately measured because it is calculated by using numerical values.

The present invention solves the problems in the prior art as described above. A smooth continuous line passing near the peak value of the pulse wave is obtained, and the pulse wave peak value with respect to the change of the cuff pressure is obtained. It is an object of the present invention to provide a blood pressure measurement device capable of reducing fluctuations in blood pressure value due to variations in.

Further, as another object, the inflection point of the continuous line is obtained as the diastolic blood pressure from the average blood pressure having the maximum value of the pulse wave peak value and the continuous line passing near the pulse wave peak value. Provided is a blood pressure measurement device capable of more accurately measuring diastolic blood pressure.

[0007]

In order to achieve the above object, a blood pressure measuring apparatus according to claim 1 comprises a pulse wave detecting means for continuously detecting a pulse wave of a living body, and a pulse wave detecting means from the pulse wave detecting means. Holding means for holding the continuous pulse wave data, and the discrete pulse wave peak value data held by the holding means is read and processed by the spline function, and smooth continuous line data is obtained from the discrete pulse wave peak values. And a spline function processing means for generating.

According to another aspect of the blood pressure measuring apparatus, a pulse wave detecting means for continuously detecting a pulse wave of a living body and a holding means for holding continuous pulse wave data from the pulse wave detecting means. Means, and a spline function processing means for reading the data of the discrete pulse wave peak value held by the holding means and processing it with a spline function, and generating smooth continuous line data from the discrete pulse wave peak value, And a detecting means for detecting a cuff pressure giving an inflection point of continuous line data from the spline function processing means as a diastolic blood pressure value.

A blood pressure measuring apparatus according to a third aspect of the present invention comprises weighting means for weighting discrete crest value data of the pulse wave from the pulse wave detecting means before the spline function processing means processes the spline function. The blood pressure measurement device according to claim 1 or 2, further comprising: It is configured.

[0010]

With the blood pressure measuring device having the above-mentioned structure according to the first and third aspects, the pulse wave of the living body is continuously detected and the data thereof is held. Then, by weighting the data of the crest value of the discrete pulse wave held, further processed by the spline function, to generate the crest value of the pulse wave obtained discretely into smooth continuous line data. There is. Therefore, the pulse wave crest value is corrected, a smooth continuous line passing near the actually measured pulse wave crest value is obtained, and fluctuations in the blood pressure value due to variations in the pulse wave crest value due to changes in the cuff pressure are reduced.

In the blood pressure measuring device according to the second and third aspects, similarly to the first aspect, the crest value of the pulse wave is processed into smooth continuous line data by processing with the spline function, and the continuous line data The cuff pressure that gives an inflection point is detected as the diastolic blood pressure value. Therefore, the average blood pressure of the cuff pressure having the maximum pulse wave peak value and the diastolic blood pressure which is the cuff pressure at the inflection point of the continuous line passing near the pulse wave peak value are accurately measured.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the blood pressure measuring device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a sphygmomanometer to which the blood pressure measurement device of the present invention is applied. In FIG. 1, this sphygmomanometer has a cuff 1 attached to the upper arm of a person to be measured, a pressure sensor 2 for detecting an air pressure in the cuff 1, and a pressure of the cuff 1 to a value indicated by a control signal C1. And a pump 3 of.
Further, after the cuff 1 is pressurized, a solenoid valve 4 for gradually exhausting the pressure according to the instruction value of the control signal C2 to reduce the pressure, and a DC amplification circuit 6 for amplifying the DC pressure signal (S1) from the pressure sensor 2 And are provided.

Further, an A / D conversion circuit 7 for converting the pressure signal (S1) from the DC amplification circuit 6 into a digital signal.
And the pressure signal (S1) from the DC amplifier circuit 6 is amplified,
An AC amplifier circuit 8 that outputs a blood pressure pulse wave signal (S2) is provided. Further, an A / D conversion circuit 9 for converting the blood pressure pulse wave signal (S2) from the AC amplification circuit 8 into a digital signal.
A pump control circuit 11 for controlling the delivery of air from the pump 3 and a solenoid valve drive circuit 12 for controlling the exhaust of the solenoid valve 4 are provided.

Further, this blood pressure monitor has a pressure signal (S1) from the A / D conversion circuits 7 and 9 and a blood pressure pulse wave signal (S).
2) is taken in to perform a smoothing spline process which will be described in detail later, a diastolic blood pressure is calculated after this process, the pump 3 is controlled by the pump control circuit 11, and the cuff is controlled by the solenoid valve drive circuit 12. The control circuit 13 has a control circuit 13 that performs control to exhaust the compressed air in 1 to reduce the pressure. Further, a key panel 14 for instructing the start of measurement and performing various operations, and a liquid crystal display (LCD) 15 for displaying processing contents and processing waveforms on the screen are provided.

The control circuit 13 takes in the pressure signal S1 and the blood pressure pulse wave signal (S2) from the A / D conversion circuits 7 and 9 and sends the control signals to the pump control circuit 11 and the solenoid valve drive circuit 12. I / O port 13a and CPU
13b, a working RAM 13c, and a ROM 13d storing a control program for this apparatus.

Next, the operation of this embodiment will be described. FIG. 2 shows the overall operation of the sphygmomanometer shown in FIG. 1 (blood pressure measurement).
6 is a flowchart showing the processing procedure of FIG. 1 and 2
In, the pump 3 is controlled by the control circuit 13 in FIG.
The cuff 1 is pressurized by being controlled to a value set in advance by the key panel 14, and the solenoid valve 4 is controlled by the control circuit 13 to depressurize the cuff 1 step by step. The pressure signal (S1) indicating the reduced pressure is sent to the 1/0 port 13a through the pressure sensor 2, the DC amplification circuit 6 and the A / D conversion circuit 7.
It is taken in by the CPU 13b of the control circuit 13 via.

At the same time, the blood pressure pulse wave signal (S2) is sent to the control circuit 13 through the pressure sensor 2, the DC amplification circuit 6, the AC amplification circuit 8 and the A / D conversion circuit 9 and the 1/0 port 13a.
Is taken in by the CPU 13b (step (indicated by S in the figure) 10). The CPU 13b searches for the maximum value point of the pulse wave waveform from the blood pressure pulse wave signal (S2) and determines it (steps 11, 1).
2). Further, the rising point of the pulse wave waveform is determined (step 13). Next, the crest value of the pulse wave waveform is determined, and it is determined whether or not the pulse wave height of the blood pressure pulse wave signal S2 during the depressurization process of the cuff 1 satisfies a predetermined termination condition (step 14, 15). As the termination condition, in this embodiment, the pulse wave peak value of 50% to 70% of the maximum peak value is 1 or less.
~ Set the case where 4 beats are detected. If not satisfied (step 15: No), the next cuff 1
The pressure is reduced (step 16) and the process returns to step 10 to repeat the above-described processing.

When the pulse wave crest value of the blood pressure pulse wave signal (S2) in the depressurizing process of the cuff 1 is determined in step 15 (step 15: Yes), the control circuit 13 causes the solenoid valve drive circuit 1 to operate.
Fully open the solenoid valve through 2. The data so far are stored in the RAM 13c of the control circuit 13, and thereafter, the peak value of the pulse wave with respect to the pressure reduction of the cuff 1 calculated by the control circuit 13 is weighted (step 17). In other words, the peak value of the pulse wave, suddenly large value when the subject suddenly moves during blood pressure measurement, or suddenly small value, so the error of the peak value of the pulse wave is reduced by weighting. To do.

There are various methods for this weighting.
For example, once the pulse wave peak value itself is temporarily subjected to smoothing spline processing, and after correcting the pulse wave peak value,
The weighting coefficient is varied depending on what percentage of the measured pulse wave crest value is different from the corrected pulse wave crest value. When the difference is within 10% of the actually measured pulse wave crest value, the weighting coefficient is set to 1, and when the difference is within 30%, the weighting coefficient is set to 0.5.

Next, the control circuit 13 shown in FIG. 1 (2) is used to obtain a smooth continuous line passing near the crest value of the pulse wave using the weighted coefficients thus obtained.
M-1) The next smoothing spline process is performed (M: natural number) (step 18). The smoothing spline processing is a kind of spline processing, and in this embodiment, the (2M-1) th order spline processing is performed among the processing methods. The smoothing spline processing is a processing method for fitting a smooth curve closest to discrete data. The smoothed approximation curve does not necessarily have to pass through the data points on the graph, so that the difference between the smoothed approximation curve and the data is the smallest as a whole, and the smoothed approximation curve itself This is a method of adjusting the smoothness of and obtaining the smoothed approximated curve. FIG. 3 is a diagram showing a smooth continuous line in which the crest value of the pulse wave with respect to the cuff pressure is corrected by smoothing spline processing. That is, in FIG. 3, the CPU 13b processes the data of the crest value of the discrete pulse wave obtained with the rise and the decompression of the pressure of the cuff 1 stored in the RAM 13c in FIG. Data of a smooth continuous line that passes near the peak value of a pulse wave is generated. This continuous line data is stored in the RAM 13c. From the curve of the peak value of the corrected pulse wave for the cuff pressure that has been subjected to smoothing spline processing in this way,
Fluctuations in blood pressure values due to variations in pulse wave crest values can be reduced.

Next, smoothing spline processing is performed, and a mean blood pressure value is calculated from the obtained smooth continuous line (step 1).
9). FIG. 4 is a diagram showing a calculation state of the average blood pressure value.
The smooth continuous line data shown in FIG. 3 is read from the RAM 13c, and the CPU 13b performs first-order differentiation. The cuff pressure having a differential value of zero is stored in the RAM 13c as a mean blood pressure value.

Next, the diastolic blood pressure value is calculated from the smooth continuous line shown in FIG. 3 (step 20). FIG. 5 is a diagram showing a calculation state of the diastolic blood pressure value. In FIG.
The smooth continuous line data shown in FIG. 3 is read from the RAM 13c, and the CPU 13b performs second-order differentiation. The cuff pressure at which the second-order value becomes zero is set as the diastolic blood pressure value in the RAM 13c.
To memorize. That is, it is possible to accurately find the inflection point of a smooth continuous line passing through the vicinity of the actually measured peak value by the second derivative, and to calculate the diastolic blood pressure based on the principle.

[0023]

As is apparent from the above description, according to the blood pressure measuring device of the first and third aspects, the pulse wave of the living body is continuously detected, and the data of the peak value of the discrete pulse wave is obtained. Are further weighted and processed with a spline function to correct the discrete pulse wave crest values into smooth continuous line data, so a smooth continuation that passes in the vicinity of the actually measured pulse wave crest value. A line is obtained, and the fluctuation of the blood pressure value due to the variation of the pulse wave crest value with respect to the change of the cuff pressure can be reduced. That is, there is an effect that an accurate mean blood pressure value and diastolic blood pressure value can be measured.

According to the blood pressure measuring device of the second and third aspects, the cuff value is processed by the spline function to generate the peak value of the pulse wave into smooth continuous line data, and the cuff which gives the inflection point of the continuous line data. Since the pressure is detected as the diastolic blood pressure value, there is an effect that the diastolic blood pressure based on the principle can be accurately measured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a sphygmomanometer to which a blood pressure measurement device of the present invention is applied.

FIG. 2 is a flowchart showing a processing procedure of overall operation of the sphygmomanometer shown in FIG.

FIG. 3 is a diagram showing a smooth continuous line in which the crest value of a pulse wave with respect to the cuff pressure is corrected by a smoothing spline process in the embodiment.

FIG. 4 is a diagram showing a calculation state of a mean blood pressure value in the embodiment.

FIG. 5 is a diagram showing a calculation state of a diastolic blood pressure value in the embodiment.

[Explanation of symbols]

 1 Cuff S1 Pressure signal S2 Blood pressure pulse wave signal 2 Pressure sensor 3 Pump 4 Electromagnetic valve 6 DC amplification circuit 8 AC amplification circuit 11 Pump control circuit 12 Electromagnetic valve drive circuit 13 Control circuit 14 Liquid crystal display (LCD)

Claims (3)

[Claims] 1. A blood pressure measuring device having a blood pressure calculating means for calculating a blood pressure from a pressure pulse wave caused by a pulsation of an artery, a pulse wave detecting means for continuously detecting a pulse wave of a living body, and the pulse wave detecting means. Holding means for holding continuous pulse wave data from the means, the blood pressure calculating means, the discrete pulse wave peak value data held by the holding means is read and processed by a spline function, smooth continuous A blood pressure measuring device comprising: a spline function processing means for generating line data; and a blood pressure calculating means for calculating blood pressure from the continuous line data. 2. The blood pressure calculating means is provided with a detecting means for detecting a cuff pressure which gives an inflection point of the continuous line data from the spline function processing means, as a diastolic blood pressure value. The blood pressure measurement device described. 3. A weighting means for weighting discrete pulse wave crest value data from the pulse wave detecting means before the spline function processing means processes the spline function. The blood pressure measurement device according to 1 or 2.