Airway geometry imaging

• US 5,882,314 A
• Filed: 12/17/1991
• Issued: 03/16/1999
• Est. Priority Date: 12/17/1991
• Status: Expired due to Term

• Current Assignee: Biomechanics Limited, Dhss, LLC
• Original Assignee: Biomechanics Limited
• Inventors: Louis, Bruno, Fredberg, Jeffrey J.
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US07/808,907
• Time in Patent Office: 2,646 Days
• Field of Search: 128/717, 128/718, 128/719, 128/720, 128/721, 128/722, 128/200.24, 128/204.22, 128/23, 128/207.13, 128/18, 128/773, 128/207.14, 128/600.1, 128/2, 128/7 , 128/661.3, 128/662.3, 128/774, 128/780, 600/529, 600/533
• US Class Current: 600/529
• 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 transient wave field representative of the geometry of the confined volume. 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 transient 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.

Claims

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

a conduit that provides a substantially lossless wave provagation medium 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 conduit length,

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 a reflected wave to form a wave field in said conduit representative of the geometry of said confined volume,

at least first and second 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 coupled to said first and second pressure-wave-sensing transducers for processing said first and second transduced signals to provide said output signal characteristic of the geometry of said confined volume,

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 provides as said output signal an area signal that is characteristic of the cross-sectional area of said confined volume as a function of the distance from said opening in said confined volume.

2. Apparatus as recited in claim 1 wherein said conduit is constructed and arranged so that said first end is formed to snugly engage an opening to an airway of an animal which airway comprises said confined volume.

3. Apparatus as recited in claim 2 wherein said conduit is constructed and arranged so that said first end is formed to snugly engage an opening to an airway of a human which airway comprises said confined volume.

4. Apparatus as recited in claim 2 wherein said conduit is constructed and arranged so that said first end is formed to snugly engage an opening to a pulmonary airway comprising said airway.

5. Apparatus as recited in claim 4 wherein said conduit is constructed and arranged so that said first end is formed to snugly engage an opening to a nasal airway comprising said airway.

6. Apparatus as recited in claim 4 wherein said conduit is constructed and arranged so that said first end is formed to snugly engage an opening to an oral airway comprising said airway.

7. Apparatus as recited in claim 1 wherein said conduit is less than 15 cm in length.

8. Apparatus as recited in claim 7 wherein said conduit is of the order of 10 cm in length.

9. Apparatus as recited in claim 8 wherein said first and second pressure-wave-sensing transducers are separated by of the order of 3.0 cm.

10. Apparatus as recited in claim 1 wherein said conduit is of the order of 15 cm in length.

11. Apparatus as recited in claim 10 wherein said first and second pressure-wave-sensing transducers are separated by of the order of 10.25 cm.

12. A method for imaging a confined volume comprising:

connecting an open first end of a conduit that provides a substantially lossless wave propagation medium 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 at least two spaced locations along said conduit; and

processing said transduced parameters to provide an output signal representative of said confined volume,

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 the cross-sectional area of said confined volume as a function of the distance from said opening in said confined volume.

17. A method in accordance with claim 12 wherein said output signal is representative of the cross-sectional area of said confined volume as a function of the distance from said opening in said confined volume.

13. Apparatus for providing an output signal indicative of the geometry of a confined volume comprising,

a conduit 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 conduit length,

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 a reflected wave on a wave field in said conduit representative of the geometry of said confined volume,

at least first and second 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 coupled to said first and second pressure-wave-sensing transducers for processing said first and second transduced signals to provide said output signal indicative of the geometry of said confined volume,

wherein said confined volume is coupled to said open first end through a body passage input and wherein said conduit comprises,

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

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

a conduit 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 conduit length,

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 a reflected wave on a wave field in said conduit representative of the geometry of said confined volume,

at least first and second 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 coupled to said first and second pressure-wave-sensing transducers for processing said first and second transduced signals to provide said output signal characteristic of the geometry of said confined volume,

wherein said confined volume is coupled to said open first end through a nostril having an input and wherein said conduit comprises,

a tube and a disposable device having an output end sized for snug engagement with the input of said nostril and an input end for snug engagement with said tube with good acoustic impedance matching and energy transmission.

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

a conduit that provides a substantially lossless wave propagation medium 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 conduit length,

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 a second wave traveling away from said opening toward said second end to form a wave field in said conduit representative of the geometry of said confined volume,

at least first and second 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 coupled to said first and second 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 the geometry of said confined volume.

16. A method for imaging a confined volume comprising,

connecting an open first end of a conduit that provides a substantially lossless wave propagation medium 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 to produce a first wave traveling towards said opening in said confined volume and a second wave traveling away from said opening towards said second end to form a wave field in said conduit representative of the geometry of said confined volume,

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.

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

a conduit 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 conduit length,

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 a reflected wave to form a wave field in said conduit representative of the geometry of said confined volume,

at least first and second 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 coupled to said first and second pressure-wave-sensing transducers for processing said first and second transduced signals to provide said output signal characteristic of the geometry of said confined volume,

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 provides as said output signal an area signal that is characteristic of the cross-sectional area of said confined volume as a function of the distance from said opening in said confined volume,

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

19. Apparatus in accordance with claim 18 wherein said conduit is substantially 15 cm in length.

20. Apparatus in accordance with claim 19 wherein said first and second pressure wave sensing electroacoustical transducers are separated by substantially 10.52 cm.

21. Apparatus in accordance with claim 18 wherein said conduit is substantially 10 cm in length.

22. Apparatus in accordance with claim 21 wherein said first and second pressure wave sensing transducers are separated by substantially 3.0 cm.