JPS5855778B2 - Korotkoff sound selection method in blood pressure measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electronic blood pressure measurement device that can distinguish Korotkoff sounds from noise and reliably capture systolic blood pressure values and diastolic blood pressure values without being affected by the noise. This relates to a sound selection method.

As previously described in Japanese Patent Publication No. 39-13980, in the process of gradually increasing (or decreasing) the cuff pressure, the blood pressure at which blood vessel sounds can be detected for the first time is defined as the diastolic blood pressure value (or systolic blood pressure value). A device has been invented that detects the blood pressure at which blood flow stops due to an increase in cuff pressure and blood vessel sounds disappear as the systolic blood pressure value (or diastolic blood pressure value).

According to the above invention, the sawtooth wave generating circuit is provided so that even if a personal connection caused by an arrhythmia occurs, it is possible to prevent an erroneous operation.

However, in the conventional device described above, if noise is input before the first blood vessel sound obtained under normal conditions, a sawtooth wave will be generated at the time the noise is input, resulting in an incorrect blood pressure value being displayed. If no input is detected within a certain period of time following the noise, the systolic blood pressure value will be displayed as the same value as the diastolic blood pressure value, and the next time a normal Korotkoff sound arrives, However, it also had the disadvantage that it did not function normally.

The present invention eliminates the drawbacks of the above-mentioned conventional devices and ensures the best performance.
The purpose of this invention is to provide a method for selecting Korotkoff sounds that can detect diastolic blood pressure values.To achieve this purpose, the present invention detects vascular sounds that occur during the process of changing cuff pressure. a detection means, a means for invalidating a signal generated within a predetermined time period after the detection of a blood vessel sound by the detection means; and a means for monitoring whether or not the detection signal is obtained, and is configured to determine that the detection signal obtained within this predetermined time is a Korotkoff sound.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In order to simplify the explanation, a device that measures blood pressure while reducing the pressure in the cuff will be described.

In Fig. 1, reference numerals 1, 2, and 3 are retrigger type monostable multi-by-breaks, and the input tricycle of the first monostable multi 1 is turned on by a signal, and its time constant τ1 is approximately 2.
sec (2 to 3 normal heartbeats),
Also, the time constant τ2 of the second monostable multi 2 is approximately 300 m5
It is set to about eC.

The values of the time constants τ1 and τ2 above are examples of the intervals between the least number of pulses detected from the pulse test subject (30 times per minute) and the highest number of pulses detected from the subject (200 times per minute). It is not limited to these values.

Also, the time constant τ3 of the third monostable multi 3 is approximately 10m5ec
The output of the third monostable multi 3 is input to the second monostable multi 2 and the first monostable multi 1.

The output of the second monostable multi 2 is introduced into the third monostable multi 3, and the operation of the third monostable multi 3 is prohibited when the second monostable multi 2 is on.

The start signal is applied to terminal X, and the Korotkoff sound is applied to terminal Y to which the sensor is connected.

The input signal applied to the terminal X is inverted and inputted to the first gate 4 consisting of an AND gate, and simultaneously inputted to the reset terminal of the flip-flop 5, and an inverted output ζ of the flip-flop 5 is derived.

In addition to the start signal S, the output signals of the first monostable multi 1 and the third monostable multi 3 are input to the first gate 4, and the flip-flop 5 is set by the signal output from the first gate 4. Transition to state.

That is, the first gate 4 keeps the flip-flop 5 in a reset state from the application of the start signal S until the first monostable multi 1 operates, and then outputs a signal according to the output of the third monostable multi 3 to reset the flip-flop 5. Set step 5.

The inverted output of the flip-flop 5 is input to the second gate 6, and the set signal is input to the systolic blood pressure display circuit 8 and the diastolic blood pressure display circuit 9, and is further input to the control timing signal generation circuit 11 to generate a timing signal, which will be described later. control the formation of

The second gate 6 is an or gate 6a as shown in FIG.
and an AND gate 6b, and an OR gate 6a.
, the inverted output Q of the flip-flop 5 and the output of the first monostable multi 1 are inputted to the AND gate 6b, and the output of the OR gate 6a and the Korotkoff sound detected at the terminal Y are input to the amplifier 10. The detection sound amplified to this level is input.

The control timing signal generation circuit 11 receives the output of the third monostable multi 3 and the inverted output Q of the flip-flop 5, and receives timing signals from the systolic pressure latch 12, counter 14, and diastolic pressure latch 13). is being entered.

That is, the control timing signal generating circuit 11 receives the output signal of the third monostable multi-layer 3, and after the trailing edge of the signal, the systolic pressure and diastolic pressure launch signals r as shown in FIG. 3 are generated.

and counter clear signal q.

, the systolic pressure launch 12 and the diastolic pressure latch 13
A launch signal is input to the counter 14, and a clear signal is input to the counter 14.

In addition to the above-mentioned timing signal, the counter 14 also receives the third gate 7.
A pulse signal output from
Input the detection signal to.

Here, the third gate 7 is a gate circuit into which the output of the third monostable multi 3 and the output of the A/D converter are input, and a pulse signal based on the pressure applied to the wristband by the voltage controlled oscillator is generated. The pulse signal is inputted via the third gate 7 to the period counter 14 with a time constant τ3 set by the third monostable Fulci 3, and a signal corresponding to the pressure applied to the cuff is formed, causing contraction. It is output to the phase pressure latch 12 and the diastole latch 13.

That is, the third gate 7 is configured to input a signal having a frequency corresponding to the pressure value to the counter 14 for a period of time determined by the output of the third monostable multi 3.

The pressure applied to the arm cuff is detected by the number of pulses counted within a certain time τ3 as in the above embodiment, or by keeping the pulse interval constant and varying the pulse counting time depending on the arm cuff and pressure. It can also be detected.

Next, the operation of the above configuration will be explained in detail using the time chart of FIG.

Pressure is gradually applied to the cuff, and the pressurization operation is stopped when the systolic blood pressure value is exceeded and the Korotkoff sounds disappear.

After this stop signal, a start signal S is input to terminal X.

The start signal S is generated using a compressor stop signal during pressurization or other manual switches.

The flip-flop 5 is reset by the start signal S, and the inverted output Q becomes S'111. Since the output of the amplifier 10 is also introduced into the second gate 6, the output of the amplifier 1
With the output of 0, the third monostable Fulci 3 is in a state where it can generate pulses.

After the start signal S is given, the detection signal K becomes so-called noise.

A case will be explained in which the signal is generated as the output signal of the amplifier 10.

Detection signal K.

The third monostable multi 3 forms a pulse signal 3° with the pulse signal of Form.

The third gate 7 is opened by the pulse signal 3° generated by the third monostable multi 31, and even if the pulse signal 3° is a signal based on noise, the number of pulses corresponding to the pressure applied to the arm cuff in that state is A pulse signal is input to the counter 14.

The count contents of the counter 14 are determined by the timing signal generation circuit 1.
Timing signal r output from 1.

It is transferred to both latch circuits 12 and 13 in parallel in synchronization with .

The contents stored in the latch circuits 12 and 13 are transferred to the display circuits 8 and 9 with the set signal of the flip-flop 5 being input, and are displayed after being converted into a signal suitable for display.

However, since the flip-flop 5 is currently in a reset state, no display is made.

The above timing signal r. is timing signal generation circuit 1
1, the trailing end of the pulse signal 3° of the third monostable multi 3 is detected, and the signal is formed according to the output of each third monostable multi 3.

The contents of the counter 14 are the timing signal r. The counter clear signal q is generated by the timing signal generation circuit 11 by the rear end of the counter clear signal q.

will be erased by

Since the output of the second monostable multi 2 is now input to the third monostable multi 3, the operation of the third monostable multi 3 is prohibited during the period τ2, and the signal input within an extremely short period of time inhibits the operation of the third monostable multi 3. Prevent it from working.

On the other hand, since the first monostable multi 1 is set to τ1: 2 sec, the pulse signal 1° continues to pulse for about 17 seconds even after the pulse signal 2° of the second monostable multi 2 turns off. Continue signal.

The above detection signal K.

is noise, within a normal period the amplifier 10
The next detection signal is not generated.

Therefore, since the next pulse signal is not formed from the third monostable multi 3, the first gate 4 remains cut off during the period τ1, and the flip-flop 5 continues to be in the reset state.
Previous detection signal K.

is determined to be noise.

That is, the detection signal K.

The pressure on the arm cuff is detected by the counter 14 and input to the launch circuits 12 and 13 through the counter 14, but since the flip-flop 5 is in the reset state, the display circuits 8 and 9 remain inactive and do not display anything. .

Next, a case will be described in which a signal is obtained from the sensor Y by blood vessel sounds detected at relatively limited intervals, that is, a case in which normal operation without noise is performed.

After the start signal S is given, the operation in response to the signal detected at the terminal Y is caused by the noise K described above.

Exactly the same operation as in the above case is performed, and a signal corresponding to the detected blood pressure value is stored in both latch circuits 12 and 13.

In a normal test state, based on the detection signal 1, 2 is detected at the next Korotkoff sound within a period set by time constants τ1 and τ2.

In response to the detection signal, 2 opens the second gate 6 to operate the third monostable multi 3, forms a pulse signal 32, and generates the next τ3.
Set.

The first monostable multi 1 receives a pulse signal 1. When the output is obtained from the third monostable multi 3, the first gate 4 is opened and the flip-flop 5 changes to the set state.

By forming the pulse signal 3□, both the first and second monostable multis 1 and 2 are retriggered, and the period t is set again.

By setting the flip-flop 5, this set signal f is input to the display circuits 8 and 9, and the contents stored in the launch circuits 12 and 13 when the detection signal is 1 are displayed.

That is, the first detection signal is 1 and the next detection signal is 2.
At the start end of , the content of 1 is displayed on the previous detection signal.

The second gate 6 has an inverted output Q of 110'' when the flip-flop 5 is set, but it is opened in a state where an output is obtained from the first monostable multi 1, and the amplifier 1
Detect the detection signal obtained at 0.

As a result of setting the flip-flop 5, the contents of the systolic pressure latch 12 and the diastolic pressure latch 13 are displayed on the display circuit 8 and the display circuit 9 by the set signal.

In this embodiment, since the blood pressure is measured while reducing the pressure in the cuff, the above display content indicates the systolic blood pressure value.

In this state, both the display circuit 8 and the display circuit 9 are displaying the same value.

If 3 is given to the third detection signal within the period retriggered by 2 to the detection signal, the same operation as in the case of 2 to the detection signal is performed.

By the third detection signal 3, a pulse signal 33 is formed from the third monostable multi 3, and the blood pressure value based on the third detection signal 3 is the signal r generated at the rear end of the signal 3.

is transferred from the counter 14 to the latch 13 and displayed at the same time.

However, according to the timing signal given from the control timing signal generation circuit 11 to the systolic pressure latch 12, the systolic blood pressure value of 1 is stored in the first detection signal, but its contents are retained and are not updated by subsequent count signals. .

On the other hand, the contents of the diastolic pressure latch 13 are sequentially updated in synchronization with the pulse signal of the third monostable multi 3 by a signal from the timing signal generation circuit 11.

If the pressure in the cuff decreases and no Korotkoff sounds are detected within a period of time, the third monostable multi 3 will no longer operate and the first monostable multi 1 will therefore not be retriggered.

Since the Q output of the flip-flop 5 is already in the off state and the output of the first monostable Maruna 1 cannot be obtained, the Q output of the third monostable multi 3
operation is prohibited, and the content of the counter 14 obtained at the last pulse signal of the third monostable Maruna 3 is determined to be a signal of diastolic pressure.

The contents of the diastolic pressure latch 13 have been updated by the output pulse of the third monostable multi 3 up to that point, so it displays the pressure at which the last pulse of the third monostable multi occurred.

The present invention can be similarly applied when detecting the diastolic blood pressure value and the systolic blood pressure value in the process of increasing the pressure in the cuff.

As described above, the present invention provides a predetermined short time (τ2) after detecting blood vessel sounds.
Noise and systolic pressure Korotkoff sounds are distinguished from noise based on whether the next detection signal is not obtained within a predetermined period of time (
1) Discriminate the obtained detection signal as a Korotkoff sound, and confirm the diastolic pressure when the last detection signal of which consecutive detection signals have been obtained within a certain period of time is obtained, and then Malfunctions due to noise can be prevented by prohibiting the input of the signal. Therefore, it is possible to eliminate the influence of noise by separating the detected signal, which is a Korotkoff sound, from the noise that occurs before and after the detection of the signal, with an extremely simple configuration. can.

Further, according to the present invention, a predetermined period of time (
If the next detection signal is obtained within τ2), this signal is invalidated, so there is no misclassification of Korotkoff sounds by f4J due to short-time interval noise, and there is no possibility of misclassifying the f4J of Korotkoff sounds. ``The Korotkoff sound can be identified without error even for double-strike (abnormal continuous occurrence) C.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device embodying the present invention, FIG. 2 is a detailed block diagram of the main parts of the device, and FIG. 3 is a time chart illustrating the operation of the device. 1.2.3... Monostable multibibreak, 4
゜6.1...Gate, 5...Flip-flop, 8゜9...Display circuit, 11...
...Control timing signal generation circuit, 12.13...
...Latch circuit, 14...Counter.

Claims (1)

[Scope of Claims] 1. Detection means for detecting blood vessel sounds generated in the process of changing cup pressure; and a predetermined period of time (τ2) after detection of blood vessel sounds by the detection means.
and means for monitoring whether or not a detection signal is obtained from the detection means within the next predetermined time (1) after the elapse of the predetermined short time (τ2). , A blood pressure system characterized in that the signal generated within the predetermined short time (τ2) is invalidated, and the detection signal obtained within the predetermined time (1) is determined to be a Korotkoff sound. Korotkoff sound selection method in measuring equipment.