JPH0741036B2 - Ultrasonic device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an apparatus for measuring the velocity of a pulse wave generated in a fluid in a tube. This type of device can be used, for example, to measure the velocity of a blood pressure pulse wave, and the blood pressure pulse wave is used to diagnose pulsatility.

[Background of the Invention]

The velocity of the blood pressure pulse wave propagating in the blood vessel is related to the degree of hardening of the blood vessel at each site, and is 4 m / sec to 10 m / se.
It is known to increase with the degree of curing up to about c. The blood pressure pulse wave velocity in the past has been one in which the pulse wave waveform is derived by a pressure sensor as described in Technical Report of the Institute of Electronics and Communication Engineers MBE83-37 (1983). This method is good for superficial blood vessels such as the carotid artery,
In the case of deep blood vessels such as the abdominal aorta, it is impossible to measure. In addition, it is difficult to prevent the pressure of other blood vessels around the target blood vessel from mixing in as noise, and therefore an error is likely to occur.

[Object of the Invention]

An object of the present invention is to provide an apparatus capable of accurately measuring a pulse wave velocity even from a position at a long distance.

[Outline of Invention]

As a result of carefully observing the tomographic image of the artery with the ultrasonic tomography apparatus, a change in the blood vessel diameter corresponding to the propagating blood pressure pulse wave was recognized. Focusing on this knowledge, the present invention generates information indicating a pulse wave (for example, a temporal change in the pipe diameter) by utilizing the reflection of ultrasonic waves at two points along the conduit. It is configured to obtain the time difference at which the corresponding points of the wave appear at these two points, and calculate the propagation velocity of the pulse wave based on this time difference and the distance between the two points to generate the information representing the pulse wave. For this purpose, Doppler detection means is used.
It is convenient to combine this mechanism with a tomographic imaging device.

Example of Invention

FIG. 1 shows a blood pressure pulse wave velocity meter as an embodiment of the present invention. The two ultrasonic transducers 1-1 and 1-2 are connected to the blood vessel 3
Are placed on the surface of the body at a distance of L, and are driven by drive circuits 2-1 and 2-2, respectively, to repeatedly generate ultrasonic pulses and receive their reflected waves. Then, the reflected wave signals S ₁ and S ₂ are generated. FIG. 2 is a waveform diagram in a period of almost one ultrasonic pulse. The reflection from blood is much smaller than that from other living tissues. In the waveforms S ₁ and S ₂ in FIG. ₂ , the period [a
-B] and [cd] have almost no reflected waves, and therefore these periods correspond to blood vessels, and points a, b, c, d are points A on the blood vessel wall in FIG. , B, C, D respectively.

Returning to FIG. 1, the waveform processing unit 4 detects and shapes the signals S ₁ and S ₂ , respectively, and a portion where no reflected wave exists, that is, the periods [ab] and [c-] in FIG. generate square wave signals g ₁ and g ₂ with durations T ₁ and T ₂ equal to d].
The pipe diameter measuring unit 5 gates and counts, for example, a clock pulse having an appropriate constant frequency with the signals g ₁ and g ₂ , respectively, to obtain the digital information h ₁ corresponding to the durations T ₁ and T _2.
generate h ₂ . Let d ₁ be the distance between points A and B on the blood vessel wall.
C, and the distance between D and d _2, if the velocity of ultrasound in the body is V, it is _{d 1 = VT 1/2 d} 2 = VT 2/2. Therefore, h ₁ and h ₂ corresponding to T ₁ and T ₂ can be regarded as representing d ₁ and d ₂ at each time point (that is, blood vessel diameter at each position).

The blood vessel diameters d ₁ and d ₂ (hence h ₁ and h ₂ ) change corresponding to the blood pressure pulse wave, respectively, as shown in FIG. 3, and the blood pressure pulse wave changes from the left in FIG. Proceeding to the right, the change in d ₂ lags the corresponding change in d _{1 by} a time τ, which is equal to the time it takes for the blood pressure pulse wave to travel the distance L. The time difference measuring unit 6 includes a correlator, calculates correlation counts for various combinations of h ₁ and h ₂ having different arrival time differences, and calculates the delay time τ based on the arrival time difference that gives the maximum value. decide. Speed determination unit 7
Receives the distance L between the transducers 1-1 and 1-2 from the distance measuring unit 8 and divides this L by τ from the time difference measuring unit 6 to determine L / τ, that is, the blood pressure pulse wave velocity. To do. The value of the distance L may be measured by the operator and manually given to the speed determination unit 7. The time difference measuring unit 6 and the speed determining unit 7 are
It can be replaced by a single data processing unit programmed accordingly.

Instead of the two transducers 1-1 and 1-2 in FIG. 1, a single linear electronic scanning ultrasonic probe 10 as shown in FIG. 4 may be used. This probe 10 has a group of transmitting / receiving elements 11 arranged in a line and an electronic switch section 12 for scanning them, and the output thereof provides a tomographic imaging apparatus.
A tomographic image of the living body is displayed on the 20 CRTs 21. By selecting two appropriate reflected wave reception outputs in the transmitting / receiving element group 11,
Used as signals S ₁ and S ₂ in FIG. Monitoring the tomogram facilitates proper placement of the probe on the desired vessel. Not only the linear type, but also any type such as sector, convex, radial type can be used.

By providing the Doppler detection means in the waveform processing unit 4 to discriminate the moving object (blood) and the stationary object (muscle), the blood vessel portion can be more accurately identified and measured. Also, if the movements of points A to D of the blood vessel wall are detected by Doppler detection, the change in blood vessel diameter as shown in FIG. 3 can be directly obtained. Therefore, this information is used instead of h ₁ and h _2. However, the same result can be obtained. Accuracy is increased by the use of Doppler detection means.

INDUSTRIAL APPLICABILITY The present invention is not limited to blood pressure pulse waves, and can be generally applied to a mechanism for transporting fluid by intermittent driving by a pump or the like through a flexible pipe.

〔The invention's effect〕

According to the present invention, even when a plurality of tubes are adjacent to each other, the pulse wave velocity can be accurately measured at a considerable distance. In the case of the blood pressure pulse wave, the pulse wave velocity of the aorta existing at a depth of about 10 cm can be measured.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram of each part in FIG.
FIG. 3 is a graph of the change in pipe diameter with time, and FIG. 4 is a block diagram of another embodiment of the present invention. 1-1, 1-2 ...... ultrasonic transducer, S _1, S ₂ ...... reflected wave reception signal, 4 ...... waveform processing unit, 5 ...... pipe diameter measuring unit 6 ...... time difference measuring unit, 7 ...... Speed determination unit.

Claims (4)

[Claims] 1. Means for emitting ultrasonic waves toward the conduit at two points along the conduit to detect respective reflected waves, and processing the detected reflected waves to process each of the two points. Means for generating information representative of the pulse wave at, and determining the time difference between the corresponding points of the pulse waves at the two points by processing the information to obtain the time difference and the distance between the two points. Means for determining the propagation velocity of the pulse wave based on the ultrasonic wave device, and the means for generating information representing the pulse wave has a Doppler detection means for the reflected waves detected at the two points. 2. The means for generating information representing the pulse wave according to claim 1, processing the reflected waves detected at successive time points to generate a series of data corresponding to the pipe diameter at each time point. Ultrasonic device including means for performing. 3. The ultrasonic device according to claim 1, wherein the means for generating information representing the pulse wave has means for detecting a temporal change in the pipe diameter by using the output of the Doppler detecting means. 4. An ultrasonic wave transmitting / receiving element group to be arranged along a conduit, a tomographic imaging means for displaying a tomographic image in response to a received reflected wave signal from the wave transmitting / receiving element group, and the wave transmitting / receiving element. A means for processing received reflected wave signals from two predetermined elements in the group to generate information representative of a temporal change of the pipe diameter at each corresponding position; and a means for processing the information and between the corresponding positions. Means for determining the time difference of the corresponding temporal changes in the tube diameter and determining the propagation velocity of the pulse wave based on the time difference and the distance between the two elements, the means for generating the information being the two elements. An ultrasonic device having a Doppler detection means for a reflected wave signal received from the device.