JPH0145368B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blood pressure wave measuring device capable of non-invasively and non-invasively measuring blood pressure waveforms in superficial blood vessels and blood vessels deep within the body.

For example, a pressure transducer is generally used to noninvasively and noninvasively measure blood pressure waveforms in superficial blood vessels such as the carotid artery; Measurement is performed while applying a certain amount of pressure to the body surface of the area. For this reason, the blood vessels at the measurement site are compressed, so the blood pressure waveform obtained by the pressure transducer does not match the blood pressure waveform obtained by actually inserting a catheter into the measurement site.

To accurately measure the blood pressure waveform at the measurement site,
Although this data is extremely important for treating and predicting diseases, conventional blood pressure wave measuring devices have not been able to provide this data.

Furthermore, if blood pressure waveforms in blood vessels deep within the body can be measured, extremely important data can be obtained for the treatment and prevention of heart diseases and the like. However, using the conventional blood pressure wave measuring device as described above, it is almost impossible to non-invasively and non-invasively measure blood pressure waveforms of blood vessels deep within the body.

Accordingly, the present invention provides a blood pressure wave measurement device that can noninvasively and noninvasively measure blood pressure waveforms of superficial blood vessels and blood vessels deep within the body.

This invention focuses on the fact that the waveform indicating a change in the diameter of a blood vessel at a measurement site is extremely similar to the blood pressure waveform at that site. The discovery and proof have already been confirmed through repeated clinical experiments by the inventors.

Next, an example of the present invention will be explained in detail with reference to FIG. 1 and subsequent figures.

In this invention, ultrasound is used to realize non-invasive and non-invasive measurements.

1 is an ultrasonic probe used for this measurement.
2 is the body surface, 3 is a superficial blood vessel (in this example, the left common carotid artery), and arrow a indicates the direction of blood flow.

The ultrasonic probe 1 has a pair of wave receiving transducers 4A and 4B for measuring blood flow velocity, and a wave transmitting and receiving transducer 5 for measuring the radial displacement of the blood vessel 3.

10 is an example of a blood pressure wave measurement circuit, and an oscillator 11 is used to obtain an excitation pulse Pf to be supplied to the transducer 5 of the probe 1.
The pulse output of The natural vibration frequency of the vibrator 5 is 6MHz. 12 indicates an output amplifier.

The echo output Sc received by the vibrator 5 (C and Sf in FIG. 2 indicate transmitted pulses) is supplied to a broadband amplifier circuit 13.

In addition, during echo output Sc, transducers 4A and 4B
Output obtained by vibration of (Doppler output)
Since Sa and Sb are mixed in, this circuit 13 is provided with a circuit (not shown) for trapping these Doppler outputs Sa and Sb.

As for the echo output Sc, as shown in FIG. 2C, echo pulses Sg and Sh corresponding to each portion of the front wall 3A and rear wall 3B of the blood vessel 3 are obtained. Moreover, since each echo pulse Sg, Sh corresponds to the outer diameter walls 3Aa, 3Ba and the inner diameter walls 3Ab, 3Bb, the echo pulses Sg ₂ , Sh ₁ and The time width corresponds to the blood vessel diameter Db at the measurement site.

Therefore, the gate pulses following the echo pulses Sg ₂ and Sh ₁ associated with the inner diameter walls 3Ab, 3Bb, respectively
A radial displacement output can be formed by Pca and Pcb (D and E in Figure 2). In this example, gate pulses Pca and Pcb are formed by a special circuit called an echo tracking circuit.

10A and 10B indicate echo tracking circuits, one circuit 10A is for forming the gate pulse Pca, and the other circuit 10B is for forming the remaining gate pulse Pcb. One echo tracking circuit 10A will be explained first.

14A is a delay oscillation circuit, which is composed of a voltage comparator 15A and a monostable multivibrator 16A triggered by its output, and this multi-output is supplied as a gate pulse Pca to a phase comparator 17A that operates as a gate circuit together with an echo pulse Sc. be done. The gate pulse Pca is the echo pulse Sg ₂ corresponding to the inner diameter wall 3Ab of the front wall 3A among the echo pulses Sc.
The front is adjusted so that it occurs at the position of .

This adjustment can be performed, for example, as follows.

First, echo output (pulse echo) Sc is displayed on an oscilloscope (not shown). In this state, the echo output Sc, which is the input to the phase comparison supply 17A, is cut off, the voltage comparator 15A compares the offset voltage Va and the reference output Ec, and the comparison output is delayed for a certain period of time by the mono multivibrator 16A. Then, the delayed gate pulse Pca is displayed on the above-mentioned oscilloscope, and the offset voltage Va is adjusted so that this gate pulse Pca coincides with the echo pulse Sg ₂ related to the inner diameter wall 3Ab in the echo output Sc.

As shown in the figure, the echo tracking circuit 10A has a closed loop configuration so as to lock the phase. Therefore, once the offset voltage Va is adjusted and the echo output Sc is input to the phase comparator 17A, this echo output can be adjusted. Echo pulse Sg ₂ fluctuates following Sc.

Therefore, now echo pulse Sg ₂ and gate pulse
If the phase relationship with Pca is as shown in Figure 3 A and B, the output of the phase comparator 17A at this time
Since Sia is as shown in C in the figure, if this is smoothed by the low-pass filter 18A, its output Ea becomes zero.

This output Ea is superimposed on the offset voltage Va obtained by the offset voltage adjusting variable resistor 19A,
Its output is supplied to voltage comparator 15A. This voltage comparator 15A is supplied with a sawtooth reference output Ec as shown in FIG. 4A. 20
is a circuit for forming this reference output Ec, and is driven by the excitation pulse Pf. Therefore, since the excitation pulse Pf has a frequency of 10 KHz, this reference output Ec also has a period corresponding to this excitation pulse Pf.

Now, since the comparison voltage is Va, the reference output Ec
When they match, the comparison output is output and the multivibrator 16A is triggered, resulting in the gate pulse Pca shown in FIG. 4B for the reason described above.

Note that the pulse width of this gate pulse Pca is selected to be 1/2 of the natural vibration period of the vibrator 5.

When the echo pulse Sg ₂ changes as shown by the broken line in Figure 3A with respect to the gate pulse Pca,
The output gated by this gate pulse Pca
Since Sia becomes as shown in D in the figure, at this time it becomes a negative smoothed output Ea, and the input voltage to the voltage comparator 15A decreases. Therefore, the gate pulse Pca
moves to the position shown in Figure 4C, and when the phase difference between the gate pulse Pca and the echo pulse _Sg2 becomes zero due to this movement, the smoothed output Ea becomes zero and the PLL
The operation stops. If the echo pulse Sg ₂ moves to the right contrary to the above, the output Sia becomes E in Figure 3,
The gate pulse Pca is also shifted to the right as shown in FIG. 4D. Through such PLL control, the gate pulse Pca follows the echo pulse _Sg2 . Here, since the phase variation of the echo pulse _Sg2 is caused by the blood flow flowing through the blood vessel 3, the displacement state of the blood vessel wall appears as a phase variation of this gate pulse Pca.

Similarly, the other echo tracking circuit 1
0B, as shown in FIG. 2E, the rear wall 3
Gate pulse corresponding to displacement of inner diameter wall 3Bb of B
Pcb is formed, and if the flip-flop circuit 21 is set with the above-mentioned gate pulse Pca and reset with this gate pulse Pcb, a pulse output Pc (FIG. 2F) having a pulse width related to the blood vessel inner diameter Db can be obtained. can be formed.

Therefore, the systolic phase of blood vessel 3 is now A in FIG.
If the diastolic phase is G in the same figure, the pulse output Pc will change from F in the same figure to I in the same figure in accordance with this blood vessel pulsation. Pulse output Pc is terminal 21a
This is output to the DC amplifier circuit 2 via the smoothing circuit 22 with a cutoff frequency of 60Hz.
3. Therefore, the output is as shown in FIG. 5A. This waveform shows the blood pressure waveform (blood pressure wave signal) at the measurement site and also shows the radial displacement waveform (radial displacement signal).

Figure 6A shows the blood pressure waveform (subject is a 31-year-old female) measured by actually inserting a catheter into the left common carotid artery, and Figure 6B shows the blood pressure waveform according to the present invention shown in Figure 1. This is a blood pressure waveform Sd obtained by measuring using a measuring device. As is clear from comparing the two, the results are the same as those measured invasively. Same figure C
shows a resurge waveform when the horizontal axis is the blood vessel diameter (diameter) at the measurement site and the vertical axis is the blood pressure value. The fact that the resurge waveform is linear in this way indicates that the relationship between the two is linear, so the radial displacement waveform can be regarded as the blood pressure waveform.

Similarly, Figure 7 shows invasive blood pressure waveforms, non-invasive blood pressure waveforms, and resurgence waveforms when a 50-year-old man is the subject, and it can be seen that the same relationship as in Figure 6 exists in this case as well. I understand.

For these reasons, if you use the above-mentioned means,
It can be seen that blood pressure waveforms in superficial blood vessels can be measured extremely accurately, non-invasively, and non-invasively.

Note that FIG. 5B shows the electrocardiogram waveform Se.

Although the above describes the blood pressure waveform of superficial blood vessels, it is easy to understand that in this invention, as long as the reflected echo Sc of the ultrasound probe 1 can be obtained, the blood pressure waveform of blood vessels deep in the body can be measured in the same way. Good morning.

As explained above, according to the present invention, since the blood pressure waveform can be measured based on the reflected echo Sc obtained from the ultrasound probe 1, it is possible to measure the blood pressure waveform non-invasively and non-invasively. Since it is possible to measure not only superficial blood vessels but also blood pressure waveforms of blood vessels deep in the body, the present invention is particularly suitable for application to measuring blood pressure waveforms of blood vessels deep in the body.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a non-invasive blood pressure wave measuring device according to the present invention, FIGS. 2 to 5 are waveform diagrams for explaining the present invention, and FIGS. 6A and 7A are blood pressure waveform diagrams, Figure 6B and Figure 7B
is a diameter displacement waveform diagram, and FIGS. 6C and 7C are oscilloscope photographs showing the relationship between blood vessel diameter and blood pressure. 1 is an ultrasonic probe, 10 is a blood pressure wave measurement circuit,
10A and 10B are first and second echo tracking circuits, Sc is a reflected echo, and Sd is a blood pressure waveform.

Claims (1)

[Claims] 1. Detect radial displacement signals corresponding to the anterior and posterior walls of the blood vessel from the reflected echoes of ultrasound emitted from the ultrasound probe, and use these radial displacement signals to determine the maximum amplitude as the systolic blood pressure and the minimum amplitude as the diastolic blood pressure. A non-invasive blood pressure wave measurement device that obtains a blood pressure wave signal as a blood pressure wave signal.