Airway geometry imaging

• US 6,440,083 B1
• Filed: 07/29/1994
• Issued: 08/27/2002
• Est. Priority Date: 12/17/1991
• Status: Expired due to Term

• Current Assignee: Dhss, LLC
• Original Assignee: Bruno Louis, Jeffrey J. Fredberg
• Inventors: Louis, Bruno, Fredberg, Jeffrey J.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/283,074
• Time in Patent Office: 2,951 Days
• Field of Search: 128/720, 128/725, 128/774, 128/780, 128/660.01, 128/660.02, 128/660.07, 128/662.03, 600/437, 600/438, 600/443, 600/459, 600/533, 600/538, 600/589, 600/593
• US Class Current: 600/533
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00

Abstract

Apparatus provides an output signal characteristic of the geometry of a confined volume. There is a conduit with an open first end for exchanging acoustical energy with the confined volume. An electroacoustical transducer is coupled to the conduit for launching acoustical energy into the conduit towards the opening in the confined volume producing an incident wave and a reflected wave to form a wave field representative of the geometry of the confined volume. In one embodiment, the acoustical energy is launched into a sidewall of the tube. At least first and second pressure-wave-sensing transducers are mounted along the length of the conduit in spaced relationship for providing first and second transduced signals representative of the wave field at spaced locations in the conduit. A processor processes the first and second transduced signals to provide an output signal characteristic of the geometry of the confined volume. In one embodiment, the processor provides high-pass filtering of the impulse response.

Claims

1. Apparatus for providing an output signal characteristic of a confined volume geometry comprising,

a conduit having a predetermined length and an interior free of sound-absorbing or energy-absorbing material for exchanging acoustical energy with said confined volume,

said conduit having an open first end adapted for communication with an opening in said confined volume and a second end separated from said first end by the length of the conduit,

a launching transducer coupled to said conduit comprising means for launching acoustical energy into said conduit producing a first wave traveling towards said opening in said confined volume and the confined volume producing a second wave traveling away from said opening toward said second end in response to the first wave, the second wave having a wave field in said conduit representative of said confined volume geometry,

a plurality to pressure-wave-sensing transducers mounted along a length of said conduit in spaced relationship for providing first and second transduced signals representative of said wave field,

and a processor means coupled to said plurality of pressure-wave-sensing transducers including means for processing said first and second transduced signals in accordance with an algorithm that takes into account said first wave and said second wave to provide said output signal characteristic of said confined volume geometry.

2. A method for imaging a confined volume comprising,

connecting an open first end of a conduit having an interior free of sound-absorbing or acoustic energy-absorbing material to an opening in said confined volume,

propagating acoustical energy inside said conduit through said open first end and into said confined volume through said opening to produce a first wave traveling towards said opening in said confined volume and the confined volume producing a second wave traveling away from said opening towards said second end in response to the first wave the second wave having a wave field in said conduit representative of said confined volume geometry,

transducing acoustic wave field parameters of said wave field at at least two spaced locations along said conduit to provide first and second transduced signals representative of said wave field,

and processing said first and second transduced signals in accordance with an algorithm that takes into account said first wave and said second wave to provide an output signal representative of a characteristic of said confined volume.

3. Apparatus for providing an output signal characteristic of a confined volume geometry comprising,

a conduit for exchanging acoustical energy with said confined volume, said conduit having a predetermined length a sidewall and an open first end in communication with an opening in said confined volume,

a launching transducer coupled to launch acoustical energy through the sidewall of said conduit and produce an incident wave towards said opening in said confined volume and the confined volume producing a reflected wave in response to the incident wave, the reflected wave having a wave field in said conduit representative of said confined volume geometry,

a plurality of pressure-wave-sensing transducers mounted along the length of said conduit in spaced relationship for providing first and second transduced signals representative of said wave field, and

a processor means for providing high-pass filtering in processing said first and second transduced signals and providing, from said processing, said output signal characteristic of said confined volume geometry.

4. Apparatus for providing an output signal characteristic of a confined volume geometry comprising,

a conduit for exchanging acoustical energy with said confined volume, said conduit having:

a sidewall;

an open first end in communication with an opening in said confined volume; and

an open second end,

a launching transducer coupled to said conduit for launching acoustical energy through the sidewall of said conduit to produce an incident wave towards said opening in said confined volume and said confined volume producing a reflected wave in response to the incident wave, the reflected wave having a wave field in said conduit representative of said confined volume geometry,

a plurality of pressure-wave-sensing transducers mounted in spaced relationship along a length of said conduit for providing first and second transducers signal representative of said wave field, and

a processor means for processing said transduced signals to provide, from said processing, a signal representative of the response of the incident wave to the confined volume and for high-pass filtering the response to produce said output signal characteristic of said confined volume geometry.

5. The apparatus recited in claim 4 where the high-pass filtering has a cutoff frequency approximately 250 Hz.

6. The apparatus as recited in claim 5 wherein said output signal is characteristic of cross-sectional area of said confined volume as a function of distance from said opening in said confined volume.

7. Apparatus as recited in claim 6 wherein said confined volume comprises an airway of an animal.

8. Apparatus as recited in claim 7 wherein said confined volume comprises an airway of a human.

9. Apparatus as recited in claim 7 wherein said airway comprises a pulmonary airway.

10. Apparatus as recited in claim 9 wherein said airway comprises a nasal airway.

11. Apparatus as recited in claim 10 wherein said airway comprises an oral airway.

12. Apparatus as recited in claim 5 wherein said conduit is less than or equal to 15 cm in length.

13. Apparatus as recited in claim 12 wherein said conduit is approximately 15 cm in length.

14. Apparatus as recited in claim 13 wherein said plurality of pressure wave sensing electroacoustical transducers are separated by approximately 10.25 cm.

15. Apparatus as recited in claim 12 wherein said conduit is approximately 10 cm in length.

16. Apparatus as recited in claim 15 wherein said plurality of pressure-wave-sensing transducers are separated by approximately 3.0 cm.

17. Apparatus in accordance with claim 5 wherein said confined volume is through a body passage input wherein said conduit comprises,

a tube and a disposable device having an output end for snug engagement with said body passage input wall input end for snug engagement with said tube with good acoustic impedance matching and energy transmission.

18. Apparatus in accordance with claim 17 wherein said body passage is a nostril, ear canal, endotracheal tue or tracheostomy tube and said disposable device output end is sized for snug engagement with the input of said nostril.

19. Apparatus for providing an output signal characteristic of a confined volume geometry comprising,

a conduit having an interior free of sound-absorbing or energy-absorbing material for exchanging acoustical energy with said confined volume,

said conduit having:

a predetermined length;

a sidewall;

an open first end adapted for communication with an opening in said confined volume; and

, a second end separated from said first end by the conduit length,

a launching transducer coupled to launch acoustical energy through the sidewall of said conduit producing a first wave traveling towards said opening in said confined volume and the confined volume producing a second wave traveling away from said opening toward said second end in response to the first wave, the second wave having a wave field in said conduit representative of the geometry of said confined volume,

a plurality of pressure-wave-sensing transducers mounted along said length of the conduit in spaced relationship for providing first and second transduced signals representative of said wave field,

and a processor means coupled to said plurality of pressure-wave-sensing transducers including means for processing said first and second transduced signals in accordance with an algorithm that takes into account said first wave and said second wave to provide said output signal characteristic of said confined volume geometry.

20. Apparatus for providing an output signal characteristic of a confined volume geometry comprising,

a conduit for exchanging acoustical energy with said confined volume,

said conduit having:

a predetermined length;

a sidewall;

an open first end adapted for communication with an opening in said confined volume; and

, a second end separated from said first end by the conduit length,

a launching transducer coupled to launch acoustical energy through the sidewall of said conduit for launching acoustical energy into said conduit producing an incident wave towards said opening in said confined volume and said confined volume producing a reflected wave in response to the incident wave, the reflected wave having a wave field in said conduit representative of the geometry of said confined volume,

a plurality of pressure-wave-sensing transducers mounted along said conduit length in spaced relationship for providing first and second transduced signals representative of said wave field, and

a processor means coupled to said plurality of pressure-wave-sensing transducers for processing said first and second transduced signals to provide said output signal characteristic of said confined volume geometry,

wherein said confined volume is characterized by cross-sectional area as a function of distance from said opening in said confined volume and said processor means provides as said output signal an area signal that is characteristic of cross-sectional area of said confined volume as a function of distance from said opening in said confined volume,

wherein said conduit is less than or equal to 15 cm in length.

21. Apparatus in accordance with claim 20 wherein said conduit is substantially 15 cm in length.

22. Apparatus in accordance with claim 21 wherein said plurality of pressure wave sensing electroacoustical transducers are separated by substantially 10.52 cm.

23. Apparatus in accordance with claim 21 wherein said conduit is substantially 10 cm in length.

24. Apparatus in accordance with claim 23 wherein said plurality of pressure wave sensing transducers are separated by substantially 3.0 cm.

25. A method for imaging a confined volume comprising:

connecting an open first end of a conduit to an opening in said confined volume;

propagating acoustical energy into a sidewall of the conduit, through said open first end, and into said confined volume through said opening to establish a pressure field in said conduit representative of said confined volume; and

transducing acoustic wave field parameters of said pressure field at a plurality of spaced locations along said conduit; and

processing said transduced parameters to provide a response of the confined volume to the propagating acoustical energy and high-pass filtering the response to provide the output signal representative of said confined volume.

26. The method recited in claim 25 wherein the conduit is formed with a second end and wherein the second end of the conduit is open.

27. Apparatus for providing an output Signal characteristic of a confined volume geometry comprising,

a conduit for exchanging acoustical energy with said confined volume,

said conduit having a predetermined length and an open first end adapted for communication with an opening in said confined volume and a second end separated from said first end by the length of the conduit,

a launching transducer coupled to said conduit for launching acoustical energy into said conduit producing an incident wave towards said opening in said confined volume and the confined volume producing a reflected wave in response to the incident wave, the reflected wave having a wave field in said conduit representative of said confined volume geometry,

a Plurality of pressure-wave-sensing transducers mounted along said length of the conduit in spaced relationship for providing first and second transduced signals representative of said wave field, and

a processor means coupled to said plurality of pressure-wave-sensing transducers for processing said first and second transduced signals produced in response to the incident wave, the reflected wave and any rereflected wave from the second end to provide a signal representative of an impulse response of the geometry and to provide said output signal characteristic of said confined volume geometry,

wherein said confined volume is characterized by cross-sectional area as a function of distance from said opening in said confined volume and said processor means provides as said output signal an area signal that is characteristic of cross-sectional area of said confined volume as a function of distance from said opening in said confined volume.

28. Apparatus as recited in claim 27 wherein said conduit is less than 15 cm in length.

29. Apparatus as recited in claim 28 wherein said conduit is approximately 10 cm in length.

30. Apparatus as recited in claim 29 wherein said first and second pressure-wave-sensing transducers are separated by approximately 3.0 cm.

31. Apparatus as recited in claim 27 wherein said conduit is approximately 15 cm in length.

32. Apparatus as recited in claim 31 wherein said first and second pressure-wave-sensing transducers are separated by approximately 10.25 cm.

33. A method for imaging a confined volume comprising:

connecting an open first end of a conduit to an opening in said confined volume;

propagating acoustical energy inside said conduit, through said open first end, and into said confined volume through said opening to establish a pressure field in said conduit representative of said confined volume;

transducing acoustic wave field parameters of said pressure field at a plurality of spaced locations along said conduit to produce signals representative of both incident and reflected waves; and

processing said transduced parameters produced in response to the incident wave, the reflected wave and any rereflected wave from a second end of the conduit to provide a signal representative of an impulse response of the confined volume and providing said output signal characteristic of said confined volume geometry and providing an output signal representative of said confined volume geometry,

wherein said confined volume is characterized by cross-sectional area as a function of distance from said opening in said confined volume and said output signal is representative of cross-sectional area of said confined volume as a function of distance from said opening in said confined volume.