JPH046731Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an automatic blood pressure measuring device that measures blood pressure using the so-called oscillometric method.

Prior Art A cuff for compressing a part of a living body and a pulse wave detection means for detecting a pulse wave which is a pressure vibration of the cuff generated in synchronization with the heartbeat of the living body, 2. Description of the Related Art Automatic blood pressure measurement devices are known that automatically determine the blood pressure value of the living body based on changes in the magnitude of pulse waves and display the same on a display. In this way, the method of determining blood pressure based on changes in the size of the pulse wave that changes with the drop in cuff pressure is usually called the oscillometric method. It has the feature that it is possible to measure blood pressure even when it is difficult to generate sound.

Problems to be Solved by the Invention Incidentally, in an automatic blood pressure measuring device employing such an oscillometric method, a complicated blood pressure value determination algorithm is normally executed every time a pulse wave is detected. In order to determine the blood pressure value with high precision, this algorithm uses the average blood pressure value determined by the maximum amplitude of the pulse wave and the diastolic blood pressure value determined by the rapid change in the rate of decrease in the pulse wave size. The system is configured such that the systolic blood pressure value is finally determined in relation to the blood pressure value and the like. For this reason, the display of the final blood pressure value is performed after the cuff pressure has decreased to around the diastolic blood pressure value. The problem was the timing.

On the other hand, it is conceivable to temporarily display the cuff pressure when the maximum value of the pulse wave difference is detected as the systolic blood pressure value. However, at the beginning of the cuff pressure drop, the overall pulse wave size gradually increases, so in this method, the maximum value of the pulse wave difference is detected every time a new pulse wave is input, and the systolic blood pressure is There was an inconvenience that the displayed value was changed sequentially, making it impossible to read a relatively accurate systolic blood pressure value.

Means to Solve the Problems The present invention was developed against the background of the above circumstances, and its gist is to compress a part of the living body, as shown in the complaint correspondence diagram in Figure 1. It is equipped with a cuff for detecting the pulse wave and a pulse wave detection means for detecting the pulse wave, which is the pressure vibration of the cuff that occurs in synchronization with the heartbeat of the living body. In an automatic blood pressure measuring device that automatically determines the blood pressure value of the living body based on changes and displays it on a display, the method includes: (1) sequentially calculating a difference value in the magnitude of the pulse wave as the pressure of the cuff decreases; (2) a difference reduction start point detection means for detecting the point in time when the difference value of the pulse wave magnitude calculated by the difference calculation means first starts to decrease after reaching the maximum; ) This differential decrease start point detecting means determines a provisional systolic blood pressure value based on the pressure in the cuff at the time when the pulse wave magnitude difference value first begins to decrease, and temporarily displays it on the display. and a display control means for displaying the image.

Effects of operation and invention By doing this, when the difference value of the pulse wave magnitude calculated by the difference calculation means first starts to decrease after reaching the maximum, the difference decrease start point detection means can detect the first point of decrease. , the display control means causes the display to display a temporary systolic blood pressure value based on the cuff at that time. Therefore, a relatively reliable systolic blood pressure value is displayed temporarily at a relatively early stage without having to wait for cuff pressure to be determined near the diastolic blood pressure value. Display requirements can be met. Furthermore, since the display of the maximum blood pressure is no longer frequently changed, a relatively accurate systolic blood pressure value can be read quickly.

Embodiment In FIG. 2, a cuff 10 that is equipped with an air bag and is wrapped around an arm in a band-like manner includes a pressure sensor 12, a constant speed exhaust valve 14, a rapid exhaust valve 16,
Electric pumps 18 are connected to each other via air piping 20. The pressure sensor 12 detects the pressure within the cuff 10 and outputs a pressure signal SP representing the pressure to the pulse wave detection circuit 22 and the cuff pressure detection circuit 24. The pulse wave detection circuit 22 includes a bandpass filter in the cuff 10 that passes signals in a frequency band that constitutes a pulse wave, which is a pressure vibration generated in synchronization with the heartbeat of a living body, and includes a bandpass filter that passes signals in a frequency band that constitutes a pulse wave, which is a pressure vibration generated in synchronization with the heartbeat of the living body. Only the pulse wave that is detected is extracted and supplied to the A/D converter 26. In addition, the cuff pressure detection circuit 24 is equipped with a low-pass filter, and the cuff pressure detection circuit 24 is equipped with a low-pass filter to detect the DC
A component, that is, a signal representing the static pressure of the cuff 10 is extracted and supplied to the A/D converter 26. The A/D converter 26 converts each input analog signal into a digital signal and supplies the digital signal to the CPU 28. In this embodiment, the pressure sensor 12, pulse wave detection circuit 22, etc. function as a pulse wave sensor that detects pulse waves.

The CPU 28 constitutes a microcomputer together with the RAM 30 and the ROM 32, and uses the temporary storage function of the RAM 30 to
The input signal is processed according to the program stored in the ROM 32, and the constant speed exhaust valve 14, the rapid exhaust valve 16, and the electric pump 18 are controlled to automatically perform blood pressure measurement, and the obtained blood pressure value is A number is displayed on the display 34.

The operation of this embodiment will be explained below with reference to the flowcharts of FIGS. 3 and 4.

In FIG. 3, first, step S1 is executed to determine whether or not the start button 36 has been operated. If it is not operated, the process is repeated, but if it is determined that it has been operated, step S2 is executed. As a result, constant speed exhaust valve 1
4 and quick exhaust valve 16 are closed,
The electric pump 18 is activated and the pressure increase of the cuff 10 is started. In step S3, it is determined whether the actual pressure P of the cuff 10 has reached a predetermined target cuff pressure Pm. This target cuff pressure
Pm is set to, for example, about 180 mmHg so that it is sufficiently higher than the systolic blood pressure value of the living body.
If it is determined in step S3 that the pressure P of the cuff 10 has not reached the target cuff pressure Pm, the process is repeated; however, if it is determined that the target cuff pressure Pm has been reached, step S4 is executed and the electric pump 18 is stopped. Constant speed exhaust valve 14 is opened. This causes the pressure in the cuff 10 to gradually decrease.

In this blood pressure lowering process of the cuff 10, the fifth
As shown in the figure, the magnitude of the pulse wave changes with changes in cuff pressure, so as explained below,
A blood pressure value is determined. First, step S5 is executed to determine whether a pulse wave has been input. When it is determined that a pulse wave has been input, the blood pressure value determination algorithm of step S6 is executed.
This blood pressure value determination algorithm basically determines the pressure of the cuff 10 as the systolic blood pressure value and the diastolic blood pressure value when the magnitude of the pulse wave changes rapidly during the increasing and decreasing processes. The system is configured such that the systolic blood pressure value is finally determined with high precision in relation to the mean blood pressure value corresponding to the maximum value of the pulse wave and the diastolic blood pressure value according to various determination conditions determined. There is.

In the following step S7, the systolic blood pressure value and the diastolic blood pressure value are determined as a result of the execution of step S6, and it is determined whether the measurement is complete. Initially, it is not completed yet, so step S5, S6, S7
is repeatedly executed, but when it is determined in step S7 that blood pressure measurement is complete, step S8 is executed.
By executing this, the rapid exhaust valve 16 is opened and the compression by the cuff 10 is released, and the measured systolic blood pressure value and diastolic blood pressure value are displayed at the systolic blood pressure display location 38 and the diastolic blood pressure location 40 on the display 34. Displayed in .

During the above operation, the interrupt routine shown in FIG. 4 is executed every time a pulse wave is input. That is, by executing step SW1, the input pulse wave magnitude A() and the cuff pressure P[A()] at this time are read. Then, step SW2 corresponding to the difference calculating means is executed, and the difference DF() in the magnitude of the pulse wave is calculated according to the following equation.

DF()=A()-A(-1)...(1) However, A() is the current pulse wave size (amplitude)
, and A(-1) is the magnitude of the previous pulse wave.

In the following step SW3, it is determined whether the difference DF (-1) calculated at the time of inputting the previous pulse wave is larger than the contents of the buffer MAX which stores the maximum value of the difference up to now. This step SW3
If the judgment in step SW4 is negative, the interrupt routine shown in Fig. 4 is terminated, but if the judgment is affirmative, step SW4 is executed and the difference DF (-1) at the previous pulse wave input is within the buffer MAX. is stored and the maximum value is updated. Then, in step SW5, it is determined whether DF(-1) calculated when the previous pulse wave was input is larger than the difference DF() calculated when the current pulse wave was input. In this way, in step SW5, in a state where the difference DF (-1) at the time of the previous pulse wave input is the maximum value, the difference DF () calculated at the time of the subsequent pulse wave input this time is the difference from the previous time. DF(-1)
This is to detect a state in which the difference has decreased, that is, the start of a decrease in the difference, and corresponds to the difference decrease start point detection means in this embodiment.

If the judgment at step SW5 is negative, the difference has not yet started to decrease, so the interrupt routine of FIG. 4 is terminated, but if the judgment is affirmative, step SW6 corresponding to the display control means is is executed, and the cuff pressure P read during the previous pulse wave input whose magnitude is A(-1)
[A(-1)] is displayed at the systolic blood pressure display location 38 of the display 34 as a provisional systolic blood pressure value.
The provisional systolic blood pressure value displayed in this manner continues until the systolic blood pressure value determined by the blood pressure value determination algorithm in step S6 is displayed.

As described above, according to the present embodiment, after the cuff 10 starts lowering the blood pressure, the difference at the time of the previous pulse wave input is calculated.
When DF (-1) is at its maximum value, a state in which the difference DF () calculated during the subsequent pulse wave input this time has decreased compared to the previous difference DF (-1), that is, the point at which the difference starts to decrease is detected. By being
A provisional systolic blood pressure value is determined based on the cuff pressure at that point and is displayed temporarily, so a relatively accurate systolic blood pressure value can be obtained relatively quickly without having to wait for the determination of the diastolic blood pressure value etc. Therefore, it is possible to satisfy the request for early display in situations where the blood pressure value is urgently desired. Therefore, medical treatment can be taken quickly in cases where urgency is required. For example, while waiting for blood pressure value determination by a blood pressure value determination algorithm would require about 20 seconds, according to this embodiment, a relatively reliable systolic blood pressure value can be obtained within a few seconds. Furthermore, frequent changes in the display of the systolic blood pressure value are eliminated, and a relatively accurate systolic blood pressure value can be read quickly.

Although one embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, in the above-mentioned embodiment, the difference DF (-1) at the time of the previous pulse wave input is the maximum value, and the difference calculated at the time of the subsequent pulse wave input this time.
When a state in which DF() has decreased from the previous difference DF(-1) is detected, the cuff pressure P[A(-1)] read at the time of inputting the previous pulse wave is used as a temporary systolic blood pressure value. For example, the cuff pressure P
[A(-1)] may be appropriately corrected. In short, the provisional systolic blood pressure value may be determined based on the cuff pressure at the time when the difference starts to decrease.

The above description is merely one embodiment of the present invention, and various changes may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the claims of the present invention. Second
The figure is a block diagram showing the configuration of an embodiment of the present invention. 3 and 4 are flowcharts for explaining the operation of the embodiment of FIG. 2. FIG. 5 is a diagram showing the relationship between the magnitude of the pulse wave and the cuff pressure. 10...cuff, 34...indicator.

Claims (1)

[Claims for Utility Model Registration] A cuff for compressing a part of a living body, and a pulse wave detection means for detecting a pulse wave that is a pressure vibration of the cuff generated in synchronization with the heartbeat of the living body, In an automatic blood pressure measuring device that automatically determines the blood pressure value of the living body based on a change in the magnitude of the pulse wave that changes with the pressure drop in the cuff and displays it on a display, Difference calculation means for sequentially calculating the difference value of the magnitude of the pulse wave, and detecting the point in time when the difference value of the pulse wave magnitude calculated by the difference calculation means first starts to decrease after reaching the maximum. and determining a provisional systolic blood pressure value based on the pressure in the cuff at the time when the difference value of the pulse wave magnitude first starts to decrease by the difference decrease start point detection means. An automatic blood pressure measuring device comprising: a display control means for temporarily displaying the same on the display;