Method and apparatus for improving the accuracy with which the speed of a fluid is measured

• US 20050256408A1
• Filed: 05/06/2005
• Published: 11/17/2005
• Est. Priority Date: 10/14/1999
• Status: Abandoned Application

• Current Assignee: Gerard Hascoet, Thierry Pechoux
• Original Assignee: Gerard Hascoet, Thierry Pechoux
• Inventors: Pechoux, Thierry, Hascoet, Gerard
• Application Number:
  US11/123,856
• Publication Number:
  US 20050256408A1
• Time in Patent Office: Days
• US Class Current: 600/454
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: G01F 1/663 by measuring Doppler frequency shift
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• CPC Class Codes: G01P 5/241 by using reflection of acoustical waves, i.e. Doppler-effect
• CPC Class Codes: G01S 15/58 Velocity or trajectory determination systems; Sense-of-movement determination systems velocity measurement in imaging systems G01S15/8979

Abstract

The present invention relates to a method and associated apparatus for improving the accuracy with which the speed of a fluid, such as a liquid, in particular blood flowing in a duct, such as a blood vessel, in particular the aorta, is measured by means of a signal emitted by a Doppler transducer (4). In characteristic manner, according to the method, the Doppler transducer is associated with a programmable memory (50) which contains at least one correction data item for correcting the Doppler signal transmitted by the transducer (4) to a transducer control and computer unit (8). Said computer unit (8) incorporates said signal correction data item in its computation (at 16) of each speed measurement on the basis of each signal emitted by the Doppler transducer, and it computes the speed value while taking account of said correction data item so as to provide a corrected measurement of the speed of said fluid, thereby improving its accuracy.

Claims

1-18. -18. (canceled)

19. A method for measuring the speed of blood flowing in the aorta by means of a signal emitted by a Doppler transducer and for measuring the diameter of the aorta, the method comprising inserting an intracorporeal probe into the esophagous of a subject, wherein:

(a) a Doppler transducer for measuring the speed of blood flowing in the aorta and an ultrasound transducer for measuring the diameter of the aorta are incorporated or integrated in the intracorporeal probe, the Doppler transducer is mounted on the probe to emit an ultrasound beam at an angle relative to the longitudinal axis of the probe, and the probe comprises a programmable memory;

(b) the Doppler transducer is associated with the programmable memory, wherein the programmable memory contains at least one signal correction data item for correcting the Doppler signal transmitted by the transducer to a transducer control and computer unit; and

(c) the computer unit incorporates the signal correction data item in computing each speed measurement on the basis of each signal emitted by the Doppler transducer, and computes the speed value taking account of the signal correction data item so as to provide a corrected measurement of the speed of the blood.

20. The method of claim 19, wherein:

(a) the programmable memory also contains at least one sensitivity data item for informing the user of a loss of sensitivity to the Doppler signal;

(b) the transducer control and computer unit verifies the sensitivity data item present in the programmable memory on each measurement of the signal transmitted by the transducer in order to verify that the sensitivity actually obtained on the signal transmitted by the transducer is not too far removed from the sensitivity value present in the programmable memory; and

(c) in the event of sensitivity going beyond a specified limit value, the transducer control and computer unit issues to the user a signal indicative of a loss of sensitivity.

21. The method of claim 19, wherein the signal correction data item is obtained from tests preferably performed at the manufacturing site while performing preliminary use tests on the Doppler transducer in order to verify the reliability of its signal.

22. The method of claim 20, wherein the sensitivity data item is obtained during tests that are preferably performed at the manufacturing site while measuring the flow speed of a fluid that is flowing at a known speed.

23. The method of claim 19, wherein the signal correction data item comprises at least the angle at which the Doppler beam is emitted by the Doppler transducer relative to the axis of the probe, so that the speed value takes account of the real working angle of the beam from the Doppler transducer.

24. The method of claim 20, wherein the sensitivity data item comprises at least one average of a plurality of sensitivity measurements obtained over a corresponding number of uses of the Doppler transducer, each sensitivity measurement resulting from the amplitude of the signal received from the transducer.

25. The method of claim 20, wherein the transducer control and computer unit continuously computes the mean of a plurality of recently calculated sensitivity measurements and compares it with the sensitivity mean initially entered as sensitivity data into the programmable memory, and, beyond a certain difference relative to the initially programmed sensitivity measurement, issues a signal to the user indicative of a loss of sensitivity.

26. The method of claim 19, wherein at least one sensitivity data item concerning the ultrasound transducer for measuring the diameter of the aorta is provided in the programmable memory, so as to verify its sensitivity over time, and likewise issue a signal to the user in the event of a loss of sensitivity.

27. The method of claim 19, wherein the Doppler transducer is mounted on the probe to emit an ultrasound beam at an angle of 60 degrees relative to the longitudinal axis of the probe.

28. An apparatus for measuring the speed of blood flowing in the aorta by means of a signal emitted by a Doppler transducer and for measuring the diameter of the aorta, said apparatus comprising a Doppler transducer for measuring the speed of blood flowing in the aorta, an ultrasound transducer for measuring the diameter of the aorta, and a programmable memory containing at least one signal correction data item for correcting the Doppler signal transmitted by the Doppler transducer to a transducer control and computer unit, wherein:

(a) means are provided to enable the computer unit to incorporate the signal correction data item in computing each speed measurement on the basis of each signal emitted by the Doppler transducer, and to compute the speed value taking account of the signal correction data item so as to provide a corrected measurement of the speed of the blood; and

(b) the Doppler transducer is incorporated or integrated in an intracorporeal probe that can be inserted into the esophagus, and the Doppler transducer is mounted on the probe to emit an ultrasound beam at an angle relative to the longitudinal axis of the probe, and wherein the probe also comprises the programmable memory connected to the transducer control and computer unit, which memory is thus secured to the probe and is dedicated thereto.

29. The apparatus of claim 28, wherein:

(a) the programmable memory also contains at least one sensitivity data item for informing the user of a loss of sensitivity to the Doppler signal;

(b) the transducer control and computer unit verifies the sensitivity data item present in the programmable memory on each measurement of the signal transmitted by the transducer in order to verify that the sensitivity actually obtained on the signal transmitted by the transducer is not too far removed from the sensitivity value present in the programmable memory;

(c) signal-issuing means are provided; and

(d) in the event of sensitivity going beyond a specified limit value, the transducer control and computer unit issues a signal to the user, via the signal-issuing means, to inform the user of a loss of sensitivity.

30. The apparatus of claim 28, wherein the programmable memory contains a signal correction data item obtained from tests preferably performed at the manufacturing site while performing preliminary use tests on the Doppler transducer in order to verify the reliability of its signal.

31. The apparatus of claim 29, wherein the programmable memory contains a sensitivity data item obtained during tests that are preferably performed at the manufacturing site while measuring the flow speed of a fluid that is flowing at a known speed.

32. The apparatus of claim 28, wherein the signal correction data item comprises at least the angle at which the Doppler beam is emitted by the Doppler transducer relative to the axis of the probe, so that the speed value takes account of the real working angle of the beam from the Doppler transducer as actually created on the probe.

33. The apparatus of claim 29, wherein the sensitivity data item comprises at least one average of a plurality of sensitivity measurements obtained over a corresponding number of uses of the Doppler transducer, each sensitivity measurement resulting from the amplitude of the signal received from the transducer.

34. The apparatus of claim 29, wherein the transducer control and computer unit continuously computes the mean of a plurality of recently calculated sensitivity measurements and compares it with the sensitivity mean initially entered as sensitivity data into the programmable memory, and, beyond a certain difference relative to the initially programmed sensitivity measurement, issues a signal to the user, via the signal-issuing means, to indicate a loss of sensitivity.

35. The apparatus of claim 28, wherein the programmable memory contains at least one sensitivity data item concerning the ultrasound transducer for measuring the diameter of the aorta, so as to verify its sensitivity over time, and likewise issue, via a signal-issuing means, a signal to the user in the event of a loss of sensitivity.

36. The apparatus of claim 28, wherein the Doppler transducer is mounted on the probe to emit an ultrasound beam at an angle of 60 degrees relative to the longitudinal axis of the probe.