Sound velocity for lung diagnosis

• US 6,383,142 B1
• Filed: 10/06/2000
• Issued: 05/07/2002
• Est. Priority Date: 11/05/1998
• Status: Expired due to Term

• Current Assignee: Isonea Limited
• Original Assignee: Karmel Medical Acoustic Technologies Ltd. (Noam Gavriely, MD)
• Inventors: Gavriely, Noam
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): Mallari, Patricia
• Application Number:
  US09/647,890
• Time in Patent Office: 578 Days
• Field of Search: 600/529, 600/561, 600/586, 600/438
• US Class Current: 600/529
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: G01L 11/04 by acoustic means

Abstract

A method and apparatus for determining the air pressure in a lung comprises making a determination of the velocity of sound in the lung and estimating the pressure within the lung based on the determined velocity. The method also includes determining a difference in phase for sound between two positions with respect to the lung.

Claims

1. A method of determining air pressure in the lung, comprising:

determining a difference in phase for sound between two positions with respect to the lung; and

estimating the pressure within the lung based on the determined phase difference.

2. A method according claim 1, and including determining a difference in phase separately and estimating the pressure separately for each lung.

3. A method according to claim 1, wherein the phase is determined at a single frequency at which sound travels preferentially within the gas in the lung.

4. A method according to claim 1, wherein the difference in phase is determined over a range of frequencies and including:

determining a relationship between phase and frequency in a portion of the range.

5. A method according to claim 4, wherein the range of frequencies is characteristic of sound that travels preferentially in the air in the lung.

6. A method according to claim 4, wherein the pressure is estimated based on a determined rate of change of phase with frequency.

7. A method according to claim 1 wherein the sound is a multi-frequency sound signal.

8. A method according to claim 7, wherein the sound is injected into the body of a person being tested.

9. A method according to claim 8, wherein the sound is a swept sound signal.

10. A method according to claim 8, wherein the sound is noise.

11. A method according to claim 9 wherein the sound is band limited to include only frequencies of sound that travel preferentially through the lungs.

12. A method according to claim 7, wherein the sound is a sound generated by a person being tested.

13. A method according to claim 12 wherein the sound is a snore.

14. A method according to claim 12 wherein the sound is a tracheal sound.

15. A method according to claim 1 wherein the sound is measured between an upper portion of a lung and a lower portion of a lung.

22. A method according to claim 1 and including determining the velocity and estimating the pressure separately for a second lung.

23. A method according to claim 1 wherein making a determination comprises:

determining a difference in phase for a sound traveling between two positions with respect to the lung.

24. A method according to claim 23 and including determining a difference in phase separately and estimating the pressure separately for each lung.

25. A method according to claim 23, wherein the phase is determated at a single frequency at which sound travels preferentially within the gas in the lung.

26. A method according to claim 23 wherein the phase is determined over a range of frequencies and including:

determining a relationship between phase and frequency in a portion of the range.

27. A method according to claim 26 wherein the range of frequencies is characteristic of sound that travels preferentially in the air in the lung.

28. A method according to claim 26 wherein the pressure is estimated based on a determined rate of change of phase with frequency.

29. A method according to claim 1 wherein the sound is a multi-frequency sound signal.

30. A method according to claim 29 wherein the sound is injected into the body of a person being tested.

31. A method according to claim 30 wherein the sound is a swept sound signal.

32. A method according to claim 30 wherein the sound is noise.

33. A method according to claim 31 wherein the sound is band limited to include only frequencies of sound that travel preferentially through the lungs.

34. A method according to claim 29 wherein the sound is a sound generated by a person being tested.

35. A method according to claim 34 wherein the sound is a snore.

36. A method according to claim 34 wherein the sound is a tracheal sound.

37. A method according to claim 1 wherein the sound is measured between an upper portion of a lung and a lower portion of a lung.

16. Apparatus for measuring air pressure in at least one lung comprising:

a) a first sensor operative for measuring a first phase of a sound at a first locality in a body when placed at said first locality;

b) a second sensor operative for measuring a second phase of a sound at a second locality in a body when placed at said second locality; and

c) calculation circuitry that estimates the pressure or a change thereof based on a difference in the measured first and second phases.

17. Apparatus according to claim 16 wherein

a) said first sensor is adapted to be placed near the upper portion of a lung; and

b) said second sensor is adapted to be placed near a lower portion of the lung.

18. Apparatus according to claim 16, and including a sound generator adapted to be placed outboard of said first sensor, such that the first and second sensors determine said phase of a signal traveling between the generator and the second sensor.

19. Apparatus according claim 16 and comprising a third sensor adapted to measure a third phase of sound when placed at a third locality with respect to a lung.

20. Apparatus according to claim 19 wherein said second locality is adjacent to one lung and said third locality is adjacent to a second lung.

21. A method of determining the air pressure in a lung, comprising:

making a determination of the velocity of sound in the lung; and

estimating the pressure within the lung based on the determined velocity.