JPS5923204B2 - electronic blood pressure monitor - Google Patents

Description

Detailed Description of the Invention The present invention relates to an electronic blood pressure monitor that measures and records systolic blood pressure and diastolic blood pressure, and particularly relates to an electronic blood pressure monitor that measures and records pulse waves as well as systolic blood pressure and diastolic blood pressure on the same recording paper. It is.

The currently commonly used blood pressure measurement method is a non-invasive blood pressure measurement method, in which a vascular compression cuff is wrapped around the subject's upper armpit to compress the blood vessels, resulting in the appearance of Korotkoff sounds. Systolic and diastolic blood pressures are indirectly measured by measuring the cuff pressure at the time of extinction using a mercury manometer or the like.

In other words, during the process of increasing cuff pressure to temporarily stop arterial blood flow, and then gradually lowering the pressure, a Korotkoff sound appears, its intensity changes to that of a yamabushi, and at a certain point the Korotkoff sound disappears. The point at which the Korotkoff sound appears is called the Swan's first point, and the cuff pressure at this point is the systolic blood pressure, and the point at which the Korotkoff sound disappears is called the Swan's fifth point, and the cuff pressure at this point is the diastolic blood pressure.

An electronic blood pressure monitor is an automated version of the above method, which physically and electrically detects Korotkoff sounds and at the same time notifies the person measuring the cuff pressure value at that time on an analog or digital display.

Detection of Korotkoff sounds in such electronic blood pressure monitors is an important function that determines their performance, and therefore a method for electrically sampling Korotkoff sounds and a method for determining systolic and diastolic blood pressure from this signal is required. Various ideas have been proposed.

However, the Korotkoff sound, especially its appearance point, is an extremely faint low sound, and the Korotkoff sound intensity rises slowly as the cuff pressure falls, so the detection signal of the Korotkoff sound sensor is very small.

This minute signal is affected by external sounds and other factors, making it difficult to detect the correct point of appearance of the Korotkoff sounds, which causes errors in systolic blood pressure measurements.

In view of the above, this invention solves the problem that it is difficult for conventional electronic blood pressure monitors to accurately detect the appearance point of Korotkoff sounds, which causes errors in systolic blood pressure measurements.
With simple operations, it is possible to accurately detect not only the appearance point of Korotkoff sounds but also their extinction point, and it is possible to obtain systolic and diastolic blood pressure values with the same accuracy as when a doctor measures them using a stethoscope. The purpose is to provide a device that can measure and record both.

That is, a cuff is wrapped around the upper arm of the subject, the cuff pressure is changed, and the change in the Korotkoff sound at that time is detected as an electrical signal. Frequency discrimination is performed on the sound component and the pulse wave component, and this pulse wave signal is further superimposed as a polarity signal opposite to the Korotkoff sound signal on a superimposed product of the cuff pressure and the Korotkoff sound signal, and this superimposed signal is guided to a recorder. By superimposing the Korotkoff sound signal and the pulse wave signal on the cuff pressure change curve in opposite directions, the pulse wave signal can be used as a recognition signal for the appearance and extinction points of the Korotkoff sound, and the pulse wave can also be used. This is related to an electronic blood pressure monitor that records measurements in parallel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram showing the blood pressure monitor of this embodiment. 1 is a cuff attached to the upper arm of the subject, and the inside has a width of about 12 cI.
A rubber bag with a length of rL% longer than 22 mm and a sensor D for detecting Korotkoff sounds are incorporated.

The Korotkoff sound sensor D is a piezoelectric transducer or the like.

When air is injected into the rubber bag through a rubber hose 2 using a rubber pressurizer 2, it compresses the brachial artery and temporarily stops blood circulation at a certain pressure.

This pressure varies depending on the subject, but it is 150 to 200 ii
It is Hg.

The detection signal from the Korotkoff sound sensor D passes through an impedance converter 3 and is guided to a bypass filter circuit 4 and a low-pass filter circuit 5.

That is, in the bypass filter circuit 4, the frequency is approximately 30 Hz.
The above frequency components are passed to extract the Korotkoff sound component, and the low-pass filter circuit 5 passes the frequency components of about 30 Hz or less to extract the pulse wave component.

They are then input to 8 recorders via 6.7 amplifiers, respectively.

On the other hand, the pressure in the rubber bag of the cuff 1 is input to a pressure/electricity converter 10 via a two-way valve 9 via a rubber hose.

The output of this pressure/electricity converter is input to a recorder 8.

The remaining one of the three-way valves 9 is opened to the atmosphere via a valve 11.

12 Measurement □ The start switch starts the recorder 8 and opens the valve 11 at the same time as the start of measurement.

Note that the impedance converter 3 to measurement start switch 12
are installed in a single box for easy operation.

The configuration of this device has been described above, and its operation will now be explained with reference to FIG. 2 and the subsequent drawings.

Now, the pressure inside the rubber bag (cuff pressure) is 150 to 200 as above.
When rn1fHg, blood circulation is temporarily stopped and the Korotkoff sound sensor D does not generate a signal.

By closing the measurement start switch 12, the recorder 8 is started and the valve 11 is opened, normally 3 miHg/sec.
At this point, the pressure in the rubber bag inside the cuff 1 decreases, and a pressure drop curve C as shown in FIG. 2 begins to be recorded on the recording paper of the recorder 8.

On this recording paper, the vertical axis is pressure P1, and the horizontal axis is time t.

When the cuff pressure decreases, blood begins to flow from Pl in FIG. 2, and a signal is output to the Korotkoff sound sensor D of the cuff 1.

It is well known that the Korotkoff sound is synchronized with the pulse wave and occurs at its cycle, and the signal from the Korotkoff sound sensor D contains both the Korotkoff sound component and the pulse wave component. .

The signal from the Korotkoff sound sensor D is divided into two systems via an impedance converter 3.

One is guided to a bypass filter circuit 4 where only the frequency components of the Korotkoff sound are extracted and become a Korotkoff sound signal, and the other is guided to a low-pass filter circuit 5 where only the frequency components of the pulse wave are extracted and become a pulse wave signal. .

Both signals are transmitted to a recorder 8 to which the cuff pressure signal from the pressure-to-electrical converter 10 is led via amplifiers 6 and 7, respectively.
and the signals of the three parties are superimposed.

Therefore, the Korotkoff sound signal and the pulse wave signal can be used as signals of opposite polarity, for example, the positive side signal of the Korotkoff sound signal is taken out, and the negative side signal of the pulse wave signal is taken out and superimposed on the cuff pressure signal. For example, on the output side of the recorder 8, a blood pressure measurement curve as shown in FIG. 2 is recorded on the recording paper 13.

As shown in Fig. 2, the blood pressure measurement curve has a waveform in which the Korotkoff sound signal Sk and the pulse wave signal Sp are superimposed vertically on the pressure drop curve (pressure change curve) C, and the cuff pressure is the diastolic blood pressure P'z.
Below, the Korotkoff sound disappears, so the pulse wave signal S
Only the waveform p is superimposed on the pressure drop curve C.

Since the pulse wave is recorded superimposed on the pressure change curve along with the Korotkoff sound, the pressure P1 at the point where the Korotkoff sound appears, that is, the systolic blood pressure value, which is difficult to judge with conventional blood pressure recording, is measured on the scale of the recording paper, and if it is blank, it is measured on a special scale. Therefore, it can be determined accurately without being affected by noise signals.

Furthermore, the diastolic blood pressure value can also be accurately read using a scale or a dedicated scale, which is the pressure P2 at the vanishing point of the Korotkoff sound signal Sk.

Furthermore, since pulse waves are recorded on the blood pressure measurement curve recorded on the recording paper 13 at intervals below the pressure P1 at the point where the Korotkoff sound appears, if there is an arrhythmia, it can be easily discovered due to the intervals.

In the embodiment, pressurization is performed manually, but the pressurizer 2 may be a pressurizing pump to automate blood pressure measurement.

As described above, according to the present invention, both the Korotkoff sound signal and the pulse wave signal are recorded on the cuff pressure change curve on the recording paper, and both signals are displayed in opposite directions, so that the recorded results are Since the appearance and extinction points of the Korotkoff sounds can be accurately detected without being affected by noise signals, accurate systolic and diastolic blood pressures can be obtained, and even after the Korotkoff sounds have disappeared, the cuff pressure change curve continues. Since the pulse wave signal is recorded, pulse wave conditions such as arrhythmia of the subject can also be monitored, which is useful for diagnosis.

The output of a single sensor is guided to a filter circuit to obtain the Korotkoff sound signal and pulse wave signal, so the detector layer is easy to use, and it is possible to simultaneously measure blood pressure and pulse wave with a simple configuration. It is possible to provide a blood pressure monitor that can record measurements.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram of a blood pressure measurement curve recorded by the apparatus shown in FIG. 1: Cuff, 2: Pressurizer, 3: Impedance converter, 4
: Bypass filter circuit, 5: Low-pass filter circuit, 6, 7: Amplifier, 8: Recorder, 9: Three-way valve, 10:
Pressure/electrical transducer, 11: Balf-12 = measurement start switch, 13: recording paper, D: Korotkoff sound sensor, C: pressure drop curve, Sk: Korotkoff sound signal, Sp: pulse wave signal.

Claims (1)

[Claims] 1. In a blood pressure monitor that electrically detects Korotkoff sounds during the cuff pressure change process and records them superimposed on the cuff pressure change curve, the output signal of the detector that detects the Korotkoff sounds is sent to a filter circuit to generate a pulse wave signal. At the same time, the pulse wave signal and the Korotkoff sound signal are converted into signals of opposite polarity, and both signals of opposite polarity are led to a recorder to which the cuff pressure signal is supplied, so that they appear on the cuff pressure change curve. An electronic blood pressure monitor characterized by superimposed recording.