Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Reexamination Certificate
1998-09-29
2001-05-29
Kwok, Helen (Department: 2856)
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
C073S054060, C600S016000
Reexamination Certificate
active
06237398
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to the field of monitoring pressure, flow and constriction parameters of plumbing and/or blood vessels. More particularly, the present invention relates to a system and method for monitoring pressure, flow rate and constriction degree and location within plumbing and blood vessels using an acoustical approach. Most particularly, the present invention relates to a system having a device transplantable within a plumbing installation or a blood vessel, which device collects data related to the above parameters and transmits that data to a second device of the system, external to the installation or body, so as to enable real-time non-invasive monitoring of such parameters.
Availability of real-time quantitative information regarding, for example, coronary flow may be of great value for the cardiac physician. For example, following a stent insertion or graft implantation, such data may be exploited for monitoring new constrictions formed in the grafted area. Similarly, real-time information regarding, for example plumbing flow may be of great value in hard-to-reach plumbing installations, such as in nuclear installations.
Prior art methods aimed at flow rate measurements may be divided into two major groups. The first group includes methods in which a detection probe is made in direct contact with the flowing substance. Therefore, methods associated with this group are generally referred to as invasive methods. An example of an invasive method is the thermodilution method, in which an invasive temperature detection probe is made in direct contact with the flowing substance.
The invasive methods suffer two major drawbacks for application in human diagnostics and plumbing installations. The first is their invasiveness. The second is related to the fact that an in-pipe flow rate is a function of location with respect to the pipe walls, wherein flow is substantially zero close to the walls and reaches a maximum in the central region of the pipe (also known as lumen). As a result, without positional information, or alternatively prolonged probing, the measurement is inaccurate.
The second group of methods aimed at flow rates measurements include non-invasive methods, therefore, methods associated with this group are generally termed imaging methods.
Various non-invasive imaging methods were developed for different applications in human diagnostics as well as in other fields. A common feature characterizing these methods is the use of a contrast agent, which agent is being traced. Imaging methods used primarily in human diagnostics include, for example, (i) X-ray based imaging methods in which X-rays are used to detect an administrated radiopaque contrast agent (e.g., iodine) used in X-ray real-time imaging methods; and (ii) Ultrasound based imaging methods in which ultrasonic waves are used to detect an administrated contrast agent, such as micro-bubbles, used in contrast-echo. Yet, in other imaging methods employed both in medicine and in other fields, radioactive materials are employed as detectable agents, which materials may be detected, for example, by various kinds of radioactivity counters.
Thus, while using imaging methods for flow rate determinations, the flow rate of an external contrast agent provided in an upstream region is measured.
The methods described hereinabove, in which external contrast agents are traced, suffer a major drawback when employed for medical purposes, since in the course of their application, an external contrast agent, some times poisonous or with yet undetermined accumulative effects is administrated to the human body.
Another imaging method aimed at flow rate determinations is the thermoimaging method in which the flow of a thermocontrast agent is monitored using an infrared camera. When applied to human diagnostics during by-pass surgeries, this method is known as thermal coronary angiography (TCA). See for example U.S. Pat. Nos. 4,995,398 and 5,375,603. However, TCA is applicable only during open chest surgeries.
As further detailed hereinunder, in a preferred embodiment the present invention takes a particular advantage of an acoustic transducer which is described in U.S. patent application Ser. No. 09/000,553, which is incorporated by reference as if fully set forth herein, which transducer serves for receiving acoustic energy transmitted from a remote source and converting such energy into electrical power for activating an electronic circuit and for transmitting acoustic information by modulating the reflection of an external impinging acoustic wave. Thus, U.S. patent application Ser. No. 09/000,553 teaches a miniature piezoelectric transducer element comprising (a) a cell element having a cavity; (b) a flexible piezoelectric layer attached to the cell member, the piezoelectric layer having an external surface and an internal surface, the piezoelectric layer featuring such dimensions so as to enable fluctuations thereof at its resonance frequency upon impinging of an external acoustic wave; and (c) a first electrode attached to the external surface and a second electrode attached to the internal surface of the piezoelectric layer. At least one of the electrodes may be specifically shaped so as to provide a maximal electrical output, wherein the electrical output may be current, voltage or power. A preferred shape of the electrodes includes two cores interconnected by a connecting member. The transducer element may function as a transmitter. When used as a transmitter, the electrodes are electrically connected to an electrical circuit including a switching element for modulating the reflected acoustic wave by controllably changing the mechanical impedance of the piezoelectric layer according to the frequency of an electrical message signal arriving from an electronic member, such as a sensor. Third and fourth electrodes may be attached to the piezoelectric layer and the electrical circuit, such that the switching element alternately connects the electrodes in parallel and anti-parallel electrical connections so as to controllably change the mechanical impedance of the piezoelectric layer.
WO 9829030 teaches a qualitative (rather then a quantitative) approach for flow determinations employing two adjacent pressure sensors.
The present invention successfully addresses the shortcomings of the presently known configurations by providing a device method and system for non-invasively and quantitatively monitoring pressure, flow and constriction parameters, which can find uses, in for example, monitoring the functionality of blood vessels in patients and of pipes in plumbing installations
SUMMARY OF THE INVENTION
According to the present invention there is provided a method of quantifying pulsatile flow in a pipe, the method comprising the steps of (a) attaching at least two spaced pressure sensors onto inner walls of the pipe; (b) using the at least two spaced pressure sensors for recording pressure records associated with each of the at least two pressure sensors within the pipe; and (c) using the pressure records for quantifying the pulsatile flow in the pipe.
According to the present invention there is further provided a method of detecting a location of an obstruction in a pipe characterized in pulsatile flow, the method comprising the steps of (a) attaching at least two spaced pressure sensors onto inner walls of the pipe; (b) using the at least two spaced pressure sensors for recording pressure records associated with each of the at least two pressure sensors within the pipe; and (c) using the pressure records for detecting the location of the obstruction in the pipe.
According to the present invention there is further provided a method of quantifying a degree of an obstruction in a pipe characterized in pulsatile flow, the method comprising the steps of (a) attaching at least two spaced pressure sensors onto inner walls of the pipe; (b) using the at least two spaced pressure sensors for recording pressure records associated with each of the at least two pressure sensors withi
Doron Eyal
Porat Yariv
Tsaliah Yosef
Kwok Helen
Remon Medical Technologies Ltd.
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