JPS6351837A - Blood pressure measuring method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field The present invention relates to improvements in blood pressure measurement methods.

Prior art A pulse synchronized signal wave generated from an artery of a living body is collected as the pressure on the artery is changed, and the peak value of each pulse synchronized signal wave is determined to indicate a series of peak values. After creating data and smoothing the peak value sequence of the peak value data, blood pressure is determined by using a blood pressure determination algorithm that determines the blood pressure value based on changes in the peak value sequence represented by the peak value data. Blood pressure measurement methods are known. For example, there is a method that detects the pulse sound generated from the artery as a heartbeat synchronized signal wave, that is, Korotkoff sound, and determines the arterial compression pressure when the Korotkoff sound occurs or disappears as a blood pressure value. A known method is to detect pressure vibrations of a cuff for compression, that is, pulse waves, and determine the arterial compression pressure when the magnitude of the pulse waves changes rapidly as the blood pressure value.

Problems to be Solved by the Invention However, when actually measuring blood pressure, the subject is not necessarily in a resting state, and equipment around the blood pressure measurement location may operate, causing the pulse synchronized signal wave that is the target of blood pressure determination to be affected. It is inevitable that various types of noise will be mixed in.

For this reason, the peak value sequence forms a complex envelope, so
In conventional blood pressure measurement methods, sufficient blood pressure measurement accuracy has not always been obtained.

First Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The gist of this method is to collect heartbeat-synchronized signal waves generated from arteries as the pressure on the arteries of the living body changes, determine the amplitude values of each heartbeat-synchronized signal wave, and then set the amplitude values in sequence in the order of generation. A blood pressure measurement method in which a sequence is created, the amplitude value sequence is smoothed, and then a blood pressure value is determined based on a change in the magnitude of the amplitude value sequence, the method comprising: (1) odd numbers in the amplitude value sequence; (2) a selection step of sequentially selecting a series of amplitude values; and (2) positioning an intermediate value among the odd numbered amplitude values selected in this selection step at the center of the series of odd numbered amplitude values. and a replacing step of replacing the amplitude value with the amplitude value to format the amplitude value sequence that is the target of the blood pressure determination.

Operation and Effect of the First Invention By doing this, the intermediate value among the odd numbered amplitude values selected in the selection step is changed to the amplitude located in the center of the series of odd numbered amplitude values by the replacement step. replaced with the value,
Since the amplitude value sequence that is the target of the blood pressure determination is shaped,
The envelope of the peak value sequence becomes smooth, making it easier to determine blood pressure and achieving sufficient measurement accuracy.

Second Means for Solving the Problems Another aspect of the present invention is to collect heartbeat-synchronized signal waves generated from the arteries of the living body as the compression intensity on the arteries changes. Then, determine the amplitude values of each of the heart rate synchronized signal waves to create an amplitude value sequence in the order of occurrence, smooth the amplitude value sequence, and then calculate the blood pressure value based on the change in the magnitude of the amplitude value sequence. A blood pressure measurement method that determines whether or not (1) the amplitude value exceeds a certain predetermined judgment reference range is sequentially compared, and when the amplitude value exceeds the judgment reference range, it is determined that the amplitude value is an abnormal value. (2) an interpolation step of inserting a value to replace the abnormal value by interpolating between normal values sandwiching the abnormal value; and (3) an amplitude value sequence interpolated by the interpolation step. a selection step of sequentially selecting a series of odd numbered amplitude values; and (4) a selection step of sequentially selecting a series of odd numbered amplitude values; and a replacing step of replacing the amplitude value with an amplitude value located at the center of the blood pressure, thereby shaping the amplitude value sequence that is the target of the blood pressure determination.

Operation and Effect of the Second Invention By doing this, the interpolation step interpolates between the normal values that sandwich the abnormal value determined in the abnormal value determination step, and a value to replace the abnormal value is inserted, so that the amplitude Abnormal values included in the value string are preferably removed. Here, abnormal values are removed from the amplitude value sequence in this way, but in the abnormal value determination process, relatively small fluctuation values may be determined as abnormal values, and a certain predetermined determination is made. Since a value that fluctuates significantly beyond the reference range is determined to be an abnormal value, there are relatively small irregularities in the envelope line of the amplitude value sequence. However, the intermediate value among the odd numbered amplitude values selected in the selection step is replaced by the amplitude value located in the center of the series of odd numbered amplitude values in the replacement step, and the target of the blood pressure determination is Since the amplitude value sequence is shaped, the envelope of the amplitude value sequence becomes even smoother, making it easier to determine blood pressure and achieving sufficient measurement accuracy.

Embodiment FIG. 2 shows an example of an automatic blood pressure measuring device to which the present invention is applied. , a pressure sensor 12 , a rapid exhaust valve 14 , a rate-limiting exhaust valve 16 , and an air pump 18 are connected via piping 20 . Pressure sensor 1
2 detects the pressure inside the cuff 10, and sends a pressure signal SP representing the pressure inside the cuff 0 to a cuff pressure detection circuit 22.
and is supplied to the pulse wave detection circuit 24. Cuff pressure detection circuit 2
2 is equipped with a low-pass filter for extracting the actual pressure of the cuff 10, that is, the cuff pressure, which is a static pressure component thereof, from the pressure signal SP, and sends the cuff pressure signal SK to the control circuit via the A/D converter 26. Supply to 28. Further, the pulse wave detection circuit 24 includes a bandpass filter for extracting a pulse wave, which is a vibration component synchronized with heartbeat, from the pressure signal sp, and controls the pulse wave signal SM via the A/D converter 26. Supplied to circuit 28.

The control circuit 28 includes a CPU 30, a ROM 32, and a RAM 3.
4. A so-called microcomputer including an output interface 36, the CPU 30 processes input signals according to a program stored in advance in the ROM 32 while utilizing the temporary storage function of the RAM 34, and processes the rapid exhaust valve 14, the rate-limiting exhaust valve 16, and the air pump 18, and a signal representing the blood pressure value determined by executing a predetermined algorithm is supplied to the display 3 to display the blood pressure value. Note that the start push button 40 is operated to start blood pressure measurement.

In the automatic blood pressure measuring device configured as described above, blood pressure values are automatically measured by executing a series of blood pressure measuring steps as shown in FIG. That is, in step S1, it is determined whether the startup push button 40 has been operated. If it is determined that the start push button 40 has not been operated, the system is kept on standby; however, if it is determined that the start button 40 has been operated, step S2 is executed, the rapid exhaust valve 14 and the rate-limiting exhaust valve 16 are closed, and the air pump 18 is turned on. The cuff 10 is driven to start pressurizing the cuff 10. In step S3, it is determined whether the pressure Pc within the cuff 10 has become equal to or higher than a predetermined target pressure Pm.

This target pressure Pm is set to a pressure sufficiently higher than the systolic blood pressure of the subject, for example, about 1801 ml+g.

As long as the judgment in step S3 is negative, the pressure increase of the cuff 10 is continued, but if the judgment in step S3 is affirmative, step S4 is executed and the drive of the air pump 18 is stopped and the rate-limiting exhaust valve 16 is opened, blood pressure reduction of the cuff 10 is started. In this blood pressure lowering process, the pressure in the cuff 10 is gradually changed at a rate of about 2 to 3 mm (1) g/sec, and during this time, the blood pressure value determination routine of step S5 is repeatedly executed to determine the blood pressure value. .

In step S5, the interrupt routine shown in FIG. 1 is repeatedly executed at relatively short intervals, for example, every 4 ms, so that the amplitude value sequence of the continuously occurring pulse waves is preprocessed and A blood pressure value is determined by executing a blood pressure determination algorithm based on a series of successive amplitude values. That is, in step SWI, for example, the fourth
It is determined whether the pulse wave shown in the figure has occurred.

The occurrence of this pulse wave is detected, for example, when the detection of the upper peak (top) and lower peak (trough) exceeds a predetermined determination level.

When the occurrence of a pulse wave is detected in this way, step S
In W2, the peak value of the pulse wave, that is, the amplitude value from the upper peak to the lower peak, is calculated, and the following step SW
3, it is determined whether the amplitude value is abnormal or not. This step SW3 corresponds to an abnormal value determination step, and the abnormality is determined by showing a physiologically impossible change in the amplitude value of the previous pulse wave.

For example, when the amplitude value of the current pulse wave is less than 1/2 and more than 4 times the amplitude value of the previous pulse wave in the state before mean blood pressure, or when the amplitude value of the previous pulse wave is in the state after mean blood pressure. It is determined that there is an abnormality when the value is 1/2 or less and 1.5 times or more.

If it is determined in step SW3 that the amplitude value of the current pulse wave is abnormal, the steps from step 85 onwards are executed again, but if it is determined that it is not abnormal, step SW4 is executed and the The amplitude value is stored together with the current cuff pressure value. Then, in step SW5, it is determined whether the current pulse wave is the second normal pulse wave following the pulse wave with abnormal amplitude. This step SW5
If the determination is negative, step SW6 is not executed, but if the determination is affirmative, step SW6 is executed and so-called amplifier filter processing is performed.

That is, in step SW6 corresponding to the interpolation step, as shown in FIG. 5, for example, the abnormal pulse waves IRI to TRR and the normal pulse wave (second Normal pulse wave)■□. Since up to 2 are stored, the normal pulse wave IR+-1 before the amplitude abnormal pulse wave Ill+ and the pulse wave ■□4□ are linearly interpolated, and the amplitude abnormal pulse wave IRI Pulse wave amplitude values A (1 +++) , i = 1, . . . , n, which replace I□, are determined as shown in FIG.

A ( I Processed and smoothed. That is, the amplitude values of five pulse waves adjacent to each other including the new pulse wave stored in the current cycle are selected in step SW7 corresponding to the selection step, and are replaced. Step SW8 corresponding to the process
Then, the intermediate value of these five amplitude values is taken as the amplitude value of the pulse wave located at the center of the five pulse wave sequences. For example, five amplitude values A(1-2), A (T-+
), A (IMED), A (1,I), A (I
. 2) is the amplitude value of the pulse wave selected in step SW7, in step SW8, the third value from the top of the above amplitude value, that is, the intermediate value A(I.,) is the amplitude value of the initial five pulse wave sequences. It is replaced with the amplitude value A (Tsin) located at the center and smoothed as shown in FIG.

Then, a blood pressure determination algorithm for determining the systolic blood pressure value and the diastolic blood pressure value in step SW9 is executed.

This blood pressure determination algorithm selects, for example, cuff pressures stored in response to sudden changes in amplitude values in the amplitude value series subjected to the amplifier filter processing and median processing, and converts them as necessary. The values are determined and stored as the systolic blood pressure value and the diastolic blood pressure value by correcting the mutual relationship and the relationship with the average blood pressure value.

Returning to FIG. 3, after the blood pressure value determination routine of step S5, step S6 is executed to determine whether the blood pressure value has been determined. At the beginning of the cuff pressure drop, the amplitude value sequence is not sufficiently formed, so even if the blood pressure determination algorithm of step SW9 is executed, the blood pressure value may be determined.The blood pressure value determination routine of step S5 and the subsequent steps are repeatedly executed. be done. However, when the blood pressure value is determined by executing the blood pressure determination algorithm in step SW9 while the steps from step 85 onwards are repeatedly executed, the determination in step S6 is affirmed and step S7 is executed.
The rapid exhaust valve 14 is activated to rapidly exhaust the air in the cuff 10 and release the compression, and the blood pressure value is displayed on the display 38.

As described above, according to this embodiment, before the blood pressure determination algorithm in step SW9 is executed, the amplitude value sequence used therein is subjected to the amplifier filter processing in steps SW5 and SW6 and the median processing in steps SW7 and SW8. As it is executed, outliers are removed and smoothed.

Therefore, the blood pressure value is easily determined by executing the blood pressure determination algorithm in step SW9, and the accuracy of blood pressure measurement is improved. For example, the actual amplitude value sequence (distribution of pulse wave size) shown in Fig. 9 becomes as shown in Fig. 10 by applying amplifier filter processing, and by further performing median processing. 1) As shown in figure.

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, in the above-described embodiment, even if the amplifier filter processing in steps SW5 and SW6 is removed, the effect that the blood pressure value can be easily determined can still be obtained.

Further, in step SW6 of the above-described embodiment, interpolation was performed between the second normal pulse wave following an abnormal value and the normal pulse wave before that abnormal value, but the first normal pulse wave following the abnormal value There is no problem even if interpolation is performed between the pulse wave and the normal pulse wave before the abnormal value.

Further, although five consecutive amplitude values are selected in step SW7 of the above-described embodiment, odd values such as three or seven may be used.

In addition, in the above embodiment, the cuff 1 is synchronized with the heartbeat.
Although the explanation is about the pulse wave that occurs at 0, it is possible to use a blood pressure measuring device that automatically determines the blood pressure value based on changes in the pulse sound (Korotkoff sound) that occurs in synchronization with the heartbeat. For smoothing, the median filter process or an amplifier filter process may be applied in addition to the median filter process.

Note that the above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 2 is a block diagram showing the configuration of an example of a device to which the present invention is applied. 3 and 1 are flowcharts illustrating the operation of the apparatus of FIG. 2. Figure 4 is the second
It is a figure which shows the waveform of the pulse wave collected with the apparatus of a figure. 5 and 6 are diagrams for explaining amplifier filter processing, and FIG. 5 is a diagram showing an amplitude value sequence of a pulse wave including abnormal values, and FIG. FIG. 7 is a diagram showing an amplitude value sequence after the value sequence has been subjected to amplifier filter processing. 7 and 8 are diagrams for explaining median filter processing, in which FIG. 7 is an amplitude value sequence before processing, and FIG.
The figures are diagrams each showing a sequence of amplitude values after processing. Fig. 9 is a diagram showing the actual distribution of amplitude values that change with changes in cuff pressure, Fig. 10 is a diagram showing the state where amplifier filter processing has been applied to it, and Fig. 1) is a diagram showing the actual distribution of amplitude values that change with changes in cuff pressure. It is a figure showing the state where processing was performed. Calculation 9--〇子 Igu Ueji no r no 8 Episode 8

Claims (4)

[Claims] (1) Collect the heartbeat synchronized signal waves generated from the artery as the compression strength against the artery of the living body changes, determine the amplitude values of each of the heartbeat synchronized signal waves, and create a series of amplitude values in the order of generation. and, after smoothing the amplitude value sequence, a blood pressure value is determined based on a change in the magnitude of the amplitude value sequence, the method comprising: smoothing the amplitude value sequence, and determining a blood pressure value based on a change in the magnitude of the amplitude value sequence, the method comprising: a selection step of sequentially selecting a series of amplitude values, and replacing an intermediate value of magnitude among the odd numbered amplitude values selected by the selection step with an amplitude value located in the center of the series of odd numbered amplitude values, and 1. A blood pressure measurement method comprising: a replacement step of shaping an amplitude value sequence to be determined. (2) The blood pressure measurement method according to claim 1, wherein the heartbeat synchronized signal wave is a pressure vibration wave generated in synchronization with a heartbeat in a cuff that compresses a part of the living body. (3) The blood pressure measurement method according to claim 1, wherein the heartbeat synchronized signal wave is a pulse sound generated from the artery when compressing the part of the living body. (4) Collect heartbeat-synchronized signal waves generated from the artery as the compression strength against the artery is changed, determine the amplitude values of each heartbeat-synchronized signal wave, and create a series of amplitude values in the order of occurrence. and, after smoothing the amplitude value sequence, a blood pressure value is determined based on a change in the magnitude of the amplitude value sequence, the amplitude value falling within a predetermined constant judgment reference range. an abnormal value determination step in which the amplitude value is determined to be an abnormal value when it exceeds the determination reference range by sequentially comparing whether or not the amplitude value exceeds the determination reference range; an interpolation step of inserting a different value; a selection step of sequentially selecting a series of odd numbered amplitude values from the sequence of amplitude values interpolated by the interpolation step; Blood pressure characterized by including a replacing step of replacing an intermediate value of magnitude with an amplitude value located at the center of the series of odd numbered amplitude values, and shaping the sequence of amplitude values to be the target of the blood pressure determination. Measuring method.