JPS6216096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present application relates to a non-invasive blood pressure measuring device, and more specifically, to a device that calculates the difference between intra-cuff arterial waves and detects the peak value to measure systolic blood pressure and diastolic blood pressure. .

Blood pressure measurement is generally divided into two types: invasive and non-invasive.

The open method involves cutting a blood vessel or inserting a needle into the blood vessel and measuring blood pressure and its fluctuations directly to a pressure gauge. Specifically, a catheter (hollow tube) or sensor filled with liquid is inserted into the measurement site, and blood pressure and its fluctuations are guided to a pressure transducer placed outside the body, and the output signal of the transducer is transmitted. Amplify, record and display.

However, blood pressure measurement using this method involves directly inserting a needle or the like into a blood vessel, which places a burden on the patient and does not allow easy measurement of blood pressure.

Therefore, except in special cases, a non-invasive method, that is, a method of measuring blood pressure indirectly from outside the body, is now widely used.

Currently, the most common indirect method is
This is a method called auscultation, and is performed according to the following steps:

First, a cuff (compression band) is wrapped around the upper arm, and the internal pressure of the cuff is increased using a pressure pump.Then, while gradually decreasing the pressure, a stethoscope is placed over the radial artery to auscultate, and the internal pressure of the cuff is increased. The systolic blood pressure and diastolic blood pressure are measured by listening to the Korotkoff sounds that occur in synchronization with the heartbeat when the cuff internal pressure matches the diastolic blood pressure value, and by confirming that the Korotkoff sounds disappear when the cuff internal pressure matches the diastolic blood pressure value.

In addition, the electric blood pressure monitors currently used apply the principle of the auscultation method described above, and after collecting Korotkoff sounds with a microphone and confirming their discrimination,
Indicate by meter etc.

However, what is particularly difficult about this sphygmomanometer is that the machine must perform the confirmation and determination of Korotkoff sounds, which are the criteria for determining maximum and diastolic blood pressure values, which is normally performed by humans. In order to determine the maximum and diastolic blood pressure values, it is necessary to confirm and judge whether the Korotkoff sounds have been detected or disappeared, but since the volume is very weak, it is difficult to detect the presence or disappearance of Korotkoff sounds. It is susceptible to skin friction noise, making blood pressure measurement difficult.

The present invention was developed to eliminate such defects in conventional blood pressure monitors, and uses a completely different principle from the previous ones, that is, it calculates the difference between arterial waves within the cuff, detects its peak value, and measures the systolic blood pressure. and devised a method for measuring diastolic blood pressure.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is a configuration diagram showing an embodiment of a blood pressure monitor according to the present invention. In the illustration, sensor 4
A pressure transducer (for example, a pressure transducer) is drawn out from the cuff 1 through a hollow tube 3. pump 2
supplies fluid to and pressurizes the cuff. In the output of the sensor, the cuff internal pressure component is amplified by the DC amplifier 5, and the intracuff arterial wave component is amplified by the AC amplifier 7. The output of the AC amplifier is sent as is, and the output of the DC amplifier is sent to an arithmetic processing circuit 8 (a microcomputer is used in the embodiment) via an A/D converter 6. Further, in the illustrated embodiment, a timer 10 and a memory 9 are provided around the microcomputer. These functions and actions will be described later.

In the illustrated embodiment, the sensor is made hollow so that the cuff is not limited to the upper arm as in conventional auscultation methods (for example, the cuff can be wrapped around a finger). The tube 3 is pulled out of the cuff, and the hollow tube 12 connecting the hollow tube, the cuff, and the cuff to the pump is filled with a liquid having the same specific gravity as blood, and the sensor can be installed at the same height as the heart. It is structured as follows. However, in the present invention, there is no problem even if the sensor is built into the cuff and the measurement is carried out by wrapping the cuff around the upper arm as in the conventional case.

Now, the pump is used to supply fluid to the cuff, pressurize it, and then gradually reduce the pressure (see Figure 2 A). Although this cuff internal pressure waveform is exactly the same as the cuff internal artery waveform shown in FIG. 2B, it is shown as a straight line for the sake of simplicity.

Next, as the cuff pressure gradually decreases, the intra-cuff arterial waveform increases sequentially and gradually decreases after reaching a certain peak value (the internal pressure of the cuff at this time corresponds to the average blood pressure (BP _av )). Next, when the difference between the intra-cuff artery waveforms is taken, the result is as shown in FIG. 2C. In the figure, positive peak values correspond to systolic blood pressure (BP _nax ), and negative peak values correspond to diastolic blood pressure (BP _nio ).

The microcomputer recognizes whether the arterial wave is detected correctly, calculates the difference in waveform energy, recognizes the two peak points of the difference as the blood pressure value, stores the pressure value at the peak point in memory 9, and performs other calculations. It has a program that controls the controls. Note that the timer 10 is for setting the measurement interval time.

The principle of blood pressure measurement according to the present invention will be explained below in comparison with measurement using conventional Korotkoff sounds.

Figure 3A shows the state in which the blood vessel 11 in the cuff 1 is crushed by the pump 2, and the blood flow (triangular wave)
collides with the pipe wall (shaded area in the figure),
The shock wave is transmitted to the sensor 4 via the fluid within the cuff and the hollow tube 3. At this time, the intra-cuff arterial waveform is small and its change is small, so almost no difference output of the arterial wave appears.

FIG. 3B shows the state when the pressurization of the pump is stopped and as the applied pressure decreases, the crushed blood vessel gradually expands and blood begins to flow. At this time, Korotkoff sounds are confirmed using conventional auscultation methods. In other words, the expansion change of the blood vessel reaches a maximum, and blood flows out, colliding with the stationary arterial blood on the distal side of the cuff.
Since the blood vessel wall shown by diagonal lines in FIG. 3B vibrates, the entire cuff that covers it vibrates, generating an arterial wave that can be clearly distinguished from the shock wave in FIG. 3B. That is, point P in FIG. 2B corresponds to this, and when viewed in FIG. 2C, which represents the difference value of the arterial wave, it corresponds to a positive peak value.

Figure 4 shows the systolic blood pressure (SBP) measured by the device of the present invention.
The actual measured values are compared with the conventional indirect method (RIVA-ROCCI method). The number of samples is 30, and the unit is mmHg. It can be seen from the figure that the actual measured values of the two coincide well.

The reason why the peak value of the difference corresponds to the diastolic blood pressure value is based on actual measurements. FIG. 5 shows actual measured values of diastolic blood pressure (DBP) using the device of the present invention in comparison with the conventional indirect method (RIVA-ROCCI method). The number of samples is
30, the unit is mmHg. As you can see from the figure,
The measured values of diastolic blood pressure using the device of the present invention are in good agreement with the values obtained using the conventional method.

The configuration and measurement principles of the blood pressure measuring device according to the present invention have been described in detail above, and the configuration provides the following unique effects.

That is, unlike the conventional method of measuring blood pressure by detecting Korotkoff sounds, the present invention requires only observation of the cuff internal pressure and arterial wave, which can be easily detected with a sensor, so the measurement conditions are relaxed, and therefore the measurement It is easy to use and is less affected by noise, so the measurement accuracy is high.

Moreover, since data is processed using a computer, blood pressure measurements over long periods of time,
Monitoring becomes possible. For example, it has become possible to measure blood pressure intermittently during sleep by controlling a timer and pump, and its uses have expanded significantly compared to conventional ones.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a configuration diagram of a measurement circuit, Fig. 2 is an explanatory diagram of a model of an observed blood pressure waveform, and Fig. 3 is an illustration of blood pressure measurement according to the present invention. Diagrams explaining the principle, Figures 4 and 5
The figure is a graph comparing the measured values between the device of the present invention and the conventional method. [Explanation of symbols of main parts], Cuff...1, Pump...2, Hollow tube...3, Sensor...4, DC amplifier...5, A/D converter...6, AC amplifier...7 , arithmetic processing circuit...8.

Claims (1)

[Claims] 1 A cuff 1, a pump 2 that supplies fluid to and pressurizes the cuff, a sensor 4 provided to the cuff or a hollow tube 3 communicating with the cuff, and amplifies the cuff internal pressure component of the output signal of the sensor. a DC amplifier 5,
an AC amplifier 7 for amplifying the intra-cuff arterial wave component;
An A/D converter 6 connected to a DC amplifier uses the output of the converter and the output of the AC amplifier 7 as input data, calculates the difference between arterial waves, detects its positive and negative peak values, and calculates the difference between the arterial waves. A non-invasive blood pressure measurement device comprising an arithmetic processing circuit 8 that detects the cuff internal pressure corresponding to the cuff pressure.