JPH0691883B2 - Continuous blood pressure measurement device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a continuous blood pressure measurement device, and more particularly to a continuous blood pressure measurement device that displays a provisional systolic blood pressure value before displaying a blood pressure value each time each blood pressure measurement is completed. It is a thing.

Conventional technology Pulse-synchronized waves such as Korotkoff sounds that are generated with changes in the pressure of a cuff wrapped around a part of a living body are sequentially sampled by the pulse-synchronized wave detection means, and based on changes in the magnitude of the pulse-synchronized waves. A continuous blood pressure measurement device that continuously measures the blood pressure value of a living body is known. In such a device, the systolic blood pressure value and the diastolic blood pressure value are each displayed at the end of each blood pressure measurement, but since the systolic blood pressure value among these blood pressure values is usually a more important index, It is desired to display the temporary systolic blood pressure value as early as possible without waiting until the systolic blood pressure value and the diastolic blood pressure value are finally determined and displayed.

Problems to be Solved by the Invention However, in determining the provisional systolic blood pressure value at the time of measuring each blood pressure, the maximum value of the difference between the pulse synchronization waves that is sequentially sampled the pulse synchronization waves corresponding to the provisional systolic blood pressure value. However, in this case, it is difficult to accurately detect the temporary systolic blood pressure value at one time because the maximum value of the difference is sequentially updated, so it is displayed once. In addition, the provisional systolic blood pressure value may be sequentially changed along with the subsequent collection of the pulse synchronization wave.

Means for Solving Problems The present invention has been made in the background of the above circumstances,
The gist of the invention is the continuous blood pressure measuring device as described above, wherein (a) the magnitude of the pulse synchronization wave when the pulse synchronization wave is sampled in a predetermined number or more at each blood pressure measurement. Regression straight line determining means for determining a regression straight line based on the points indicating the magnitudes of the pulse synchronization waves in the two-dimensional coordinates of the axis indicating the cuff pressure and the axis indicating the cuff pressure or time, and (b) determining the regression line. On the regression line determined by the means, an expected value determination means for determining an expected value of the magnitude of the pulse synchronization wave next to the pulse synchronization wave used for the determination of the regression line, and (c) determination of the expected value. Compare the expected value determined by means with the magnitude of the actual pulse synchronization wave,
Temporary systolic blood pressure value determining means for determining a temporary systolic blood pressure value based on the fact that the actual pulse synchronization wave exceeds the expected value,
(D) Display means for displaying the temporary systolic blood pressure value determined by the temporary systolic blood pressure value determining means prior to the true systolic blood pressure value determined thereafter.

By doing so, when the pulse synchronization wave is sampled at a predetermined number or more during each blood pressure measurement, the regression line determining means determines the magnitude of the pulse synchronization wave in the two-dimensional coordinates. The regression line is determined based on the regression line, on the regression line, by the expected value determination means,
An expected value of the magnitude of the pulse synchronization wave next to the pulse synchronization wave used to determine the regression line is determined. Then, the provisional systolic blood pressure value determining means compares the expected value with the magnitude of the actual pulse synchronization wave, and determines the provisional systolic blood pressure value based on the fact that the actual pulse synchronization wave exceeds the expected value. Along with
The temporary systolic blood pressure value is displayed by the display means prior to the true (formal) systolic blood pressure value that is subsequently determined.

EFFECT OF THE INVENTION As a result, the provisional systolic blood pressure value is determined early without waiting until the true systolic blood pressure value is displayed at each blood pressure measurement. Moreover, since the provisional systolic blood pressure value is determined based on the fact that the actual pulse synchronization wave exceeds the expected value determined on the regression line, the provisional systolic blood pressure value is determined based on the maximum value of the difference between the pulse synchronization waves. Compared to the case of determining the systolic blood pressure value, the temporarily displayed systolic blood pressure value is not changed, and a relatively reliable value is provisionally displayed.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a diagram showing a control circuit of a continuous blood pressure measuring device to which the present invention is applied, and 10 is a rubber bag-like cuff wound around the upper arm of the human body or the like. The cuff 10 has a pressure sensor 12,
An air pump 14, a throttle 16 for slow exhaust, a solenoid valve 18, and a solenoid valve 20 for rapid exhaust are connected via a pipe 22. The pressure sensor 12 supplies a pressure signal SP representing the pressure in the cuff 10 to the static pressure discrimination circuit 24. The static pressure discrimination circuit 24 is equipped with a low-pass filter, discriminates the cuff pressure signal SK representing the steady pressure included in the pressure signal SP, and outputs the cuff pressure signal SK.
It is supplied to the CPU 28 via the A / D converter 26.

A microphone 30 is provided inside the cuff 10.
The microphone 30 detects a pulse sound (Korotkoff sound, hereinafter referred to as K sound) generated from the upper arm of the person to be measured, and supplies the K sound signal SO representing the K sound to the bandpass filter 32. This K
The sound corresponds to the pulse synchronization wave of this embodiment. Bandpass filter 32
Is for passing a signal having a frequency component of, for example, 30 to 80 Hz, and supplies the passed K sound signal SO to the CPU 28 via the A / D converter 34.

The CPU 28 is connected to the ROM 36, the RAM 38, the display unit 40, and the output interface 42 via a data bus line, executes signal processing while utilizing the storage function of the RAM 38 according to a program stored in the ROM 36 in advance, and Pump 14
While controlling the solenoid valves 18 and 20, a series of blood pressure measurement operations are executed, a predetermined blood pressure value is determined based on the K sound signal SO and the cuff pressure signal SK, and the blood pressure value is displayed on the display 40. Let

The operation of this embodiment will be described below with reference to the flowchart of FIG.

When the power is turned on, the initial process of step S1 is executed. Then, by performing step S2, whether the blood pressure measurement has been started based on whether the measurement start pushbutton switch 44 has been operated or whether the timer counter provided in the starting circuit (not shown) has expired. It is determined whether or not. If this determination is negative, step S2 is repeatedly executed to enter the standby state, but if the determination of step S2 is positive, step S3 is executed, so that both solenoid valves 18 and 20 are Both are closed and the air pump 14 is started to increase the pressure in the cuff 10.
Next, in step S4, it is determined whether or not the cuff pressure P exceeds a predetermined constant target cuff pressure Pm. This target cuff pressure Pm is a pressure sufficiently higher than the systolic blood pressure value, for example, a value of about 180 mmHg. Cuff pressure P is the target cuff pressure P
When m has not been exceeded yet, steps S3 and S4 are repeatedly executed, but when the cuff pressure P exceeds the target cuff pressure Pm, step S5 is executed, whereby the air pump 14 is stopped and the solenoid valve 18 is executed. Is opened, and the gentle pressure reduction of the cuff 10 is started. Subsequent steps
In S6, the index counter i is cleared. The index counter i indicates the index of data representing the magnitude of the K sound and the cuff pressure P at that time, which will be described later. Then, when step S7 is executed,
It is determined whether or not the K sound signal SO has been collected. If this judgment is denied, step S7 is repeatedly executed, but if the judgment is affirmed, the magnitude of the collected K sound signal SO (hereinafter, simply the magnitude of the K sound) is the cuff at that time. It is stored in the RAM 38 together with the pressure P. Therefore, in this embodiment, step S7, the microphone 30, the bandpass filter 32, and the like constitute the pulse synchronization wave detection means.
In the following step S8, it is determined whether or not the flag F is 1. The flag F indicates that the provisional systolic blood pressure value has been determined when the flag F is 1, and indicates that the provisional systolic blood pressure value has not yet been determined when the flag F is 0. Step
If the determination in S8 is negative, step S9 is executed to add 1 to the index counter i, and step S10 is executed to store the volume of the K sound in the storage location corresponding to the index counter i. Data representing the cuff pressure P at that time is stored. In step S11, it is determined whether or not the index counter i is, for example, 5 or more, that is, 5 or more K sounds are sampled. If this judgment is negative, steps S7 to S11 are repeatedly executed to sequentially collect K sounds, but if the judgment of step S11 is affirmative, the following step S12 is executed, so that K sounds In the two-dimensional coordinates of the axis indicating the loudness of c and the axis indicating the cuff pressure P, the regression line is determined based on the point indicating the magnitude of the K sound. That is, assuming that K sound data is obtained as shown in FIG. 4, for example, the regression line a is calculated based on the points indicating the magnitudes of the three K sounds respectively corresponding to the index counters i-2 to i-4. Is determined. In the following step S13, on the regression line a, the K sound next to the K sound used to determine the regression line a, that is, the expected value Th1 of the volume of the K sound corresponding to the index counter i-1, and The expected value Th2 of the volume of the K sound corresponding to the index counter i is determined. In the present embodiment, step S12 corresponds to regression line determination means and step S13 corresponds to expected value determination means. Next, step S14 is executed to determine whether or not the actual volume K (i-1) of the K sound corresponding to the index counter i-1 is larger than the expected value Th1. If denied, step
S7 to S14 are repeatedly executed, but if the determination in step S14 is affirmative, the following step S15 is executed.
In step S15, the actual volume K of the K sound K (i)
Is larger than the expected value Th2, and if this judgment is affirmed, the subsequent step S16 is executed, whereby the K sound of the magnitude K (i-1) is collected. The cuff pressure P1 is determined as a temporary systolic blood pressure value. Next, in step S17, the flag F is set to 1, and step S18 is executed to display the temporary systolic blood pressure value on the display 40. Therefore, in the present embodiment, steps S14 to S16 constitute the temporary systolic blood pressure value determining means, and step S18 and the display 40 etc. constitute the displaying means.

If the determination in step S15 is negative, step S19 is executed to change the K sound volume K (i) corresponding to the index counter i to K (i-1), and Step S20 is executed to set the index counter i to i-1. As a result, the K sound data determined to be smaller than the expected value Th2 in step S15 is deleted, and steps S7 to S15 and steps S19, S are performed until the determination in step S15 is affirmed.
20 is executed repeatedly.

When the temporary systolic blood pressure value is displayed in step S18,
By executing the blood pressure value determination routine of step S21, a well-known blood pressure value determination algorithm for determining the systolic blood pressure value, the diastolic blood pressure value, etc. based on the change in the loudness of each K sound sampled. Executed, this
The maximum blood pressure value and the minimum blood pressure value are determined. In the following step S22, it is determined whether the blood pressure measurement is completed. If the blood pressure measurement is not completed, the steps S7 and S8 are executed, but since the flag F is judged to be 1 in step S8, the steps S9 to S20 are skipped. Steps S7, S8, S
21, S22 is repeatedly executed. When it is determined that the blood pressure measurement is completed in step S22, step S23
Is executed to clear the flag F. Next, when step S24 is executed, the blood pressure value is displayed on the display 40, and the solenoid valve 20 is opened as necessary to rapidly exhaust the pressure in the cuff 10. After that, the blood pressure measurement is continuously performed by performing step S2 and subsequent steps again.

Thus, according to the present embodiment, the provisional systolic blood pressure value is determined early without waiting until the true systolic blood pressure value is displayed at each blood pressure measurement. Moreover, since the provisional systolic blood pressure value is determined based on the fact that the actual K-sound loudness exceeds the expected value determined on the regression line, the maximum value of the difference between the loudnesses of each K-sound is determined. Compared with the case where the temporary systolic blood pressure value is determined based on this, the temporarily displayed systolic blood pressure value is not changed, and a relatively reliable value is provisionally displayed.

Further, according to the present embodiment, the two actual K tones K
When it is determined that both (i-1) and K (i) are larger than the expected values Th1 and Th2, the cuff pressure P corresponding to the K (i-1) is determined as a temporary systolic blood pressure value. Since it is configured, the reliability of the temporary systolic blood pressure value is further improved.

Further, according to the present embodiment, since it is not necessary to perform the smoothing process on each sampled K sound signal SO, the temporary systolic blood pressure value is determined relatively quickly.

It should be noted that in the above-described embodiment, the expected value is determined for each of the two K sounds next to and after the K sound used to determine the regression line, and the actual K sound size is determined. When both exceed the expected values, the cuff pressure P at the time when the K sound immediately after the K sound used to determine the regression line is collected is determined as the provisional systolic blood pressure value, but this is not always necessary. However, for example, when the actual K-sound loudness exceeds two or more expected values, based on the cuff pressure P when any K-sound corresponding to the second and subsequent expected values is sampled. It may be determined, or may be determined based on the average of each cuff pressure P when a plurality of actual K sounds exceeding each expected value are sampled.

In addition, in the above-described embodiment, when five or more K sounds are sampled, the regression line is determined based on the points indicating the magnitudes of the three K sounds. , It is not always necessary. If at least 3 K sounds are collected, the regression line can be determined and 4 or more K sounds can be determined.
The regression line may be determined based on the sound.

Further, in the above-described embodiment, the regression line is determined within the two-dimensional coordinates of the axis indicating the magnitude of the K sound and the axis indicating the cuff pressure P. It may be determined within two-dimensional coordinates of the axis shown and the axis showing time.

Further, in the above-mentioned embodiment, each K sound signal SO
Alternatively, the regression line may be determined after the smoothing process is performed.

Further, in the above-described embodiment, the blood pressure value determination routine is executed in accordance with the sampling of the K sound signal SO after the provisional systolic blood pressure value is determined, but this is not always necessary. Alternatively, the blood pressure value can be determined by so-called batch processing after all K sound signals SO have been collected.

Besides, the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention. FIG. 2 is a block diagram showing an embodiment of the present invention. Figure 3 is second
6 is a flowchart for explaining the operation of the embodiment in the figure. FIG. 4 is a diagram showing an example of the collected K sound signal and is a diagram for explaining a regression line and an expected value. 10: Cuff 30: Microphone 32: Bandpass filter 40: Display

Claims (1)

[Claims] 1. A pulse-synchronous wave that is generated with a change in pressure of a cuff wound around a part of a living body is sequentially sampled by a pulse-synchronous wave detecting means, and the pulse-synchronous wave is detected based on a change in the magnitude of the pulse-synchronous wave. A continuous blood pressure measuring device for continuously measuring a blood pressure value of a living body, and when each of the pulse synchronization waves is sampled in a predetermined number or more at each blood pressure measurement, an axis indicating the magnitude of the pulse synchronization wave. Regression line determining means for determining a regression line based on a point indicating the magnitude of the pulse synchronization wave in a two-dimensional coordinate with an axis indicating cuff pressure or time, and a regression line determined by the regression line determining means In the above, expected value determination means for determining the expected value of the magnitude of the pulse synchronization wave next to the pulse synchronization wave used for determination of the regression line, and the expected value determined by the expected value determination means and the actual value Compare the magnitude of the pulse sync wave, The provisional systolic blood pressure value determining means for determining a provisional systolic blood pressure value based on the fact that the actual pulse synchronization wave exceeds the expected value, and the provisional systolic blood pressure value determined by the provisional systolic blood pressure value determining means, A continuous blood pressure measuring device, comprising: a display unit for displaying the true systolic blood pressure value determined thereafter.