Determining endotracheal tube placement using acoustic reflectometry

• US 20030034035A1
• Filed: 08/14/2002
• Published: 02/20/2003
• Est. Priority Date: 08/14/2001
• Status: Abandoned Application

• Current Assignee: The Alfred E. Mann Institute For Biomedical Engineering At The University Of Southern California (University of Southern California)
• Original Assignee: University of Southern California
• Inventors: Raphael, David T.
• Application Number:
  US10/218,480
• Publication Number:
  US 20030034035A1
• Time in Patent Office: Days
• US Class Current: 128/207.14
• CPC Class Codes: A61M 16/0411 with means for differentiating between oesophageal and tracheal intubation
• CPC Class Codes: A61M 16/0488 Mouthpieces; Means for guiding, securing or introducing the tubes guiding or introducing with laryngoscopes A61B1/267; holding devices on the body A61M25/02
• CPC Class Codes: A61M 2205/3375 Acoustical, e.g. ultrasonic, measuring means
• CPC Class Codes: A61M 2209/02 Equipment for testing the apparatus

Abstract

Determining the placement of an endotracheal tube in a patient. The invention evaluates discontinuities in the medium surrounding the endotracheal tube, such as the airway, as a function of distance past an end of the endotracheal tube. Using a loudspeaker to generate sound waves, the sound waves propagate through a coiled wavetube, a connecting adapter, and an endotracheal tube, into the area of interest. With a processing system, reflected sound waves which return from the cavity back to a microphone within the wavetube are analyzed and an area-distance curve of the area in interest is constructed.

Claims

1. A method for determining the position inside of a patient of an endotracheal intubation using an endotracheal tube having a proximal and a distal end comprising:

a) inserting the distal end of the endotracheal tube through the mouth or nose of a patient;

b) sending sound waves through a wavetube in acoustic communication with the endotracheal tube and with the body cavity of the patient;

c) receiving reflections of the sound waves within the wavetube;

d) transforming the reflections into data representative of the cross-sectional area of the body cavity in the patient throughout a range of distances beyond the distal end of the endotracheal tube;

e) displaying an image of the cross-sectional area of the body cavity in the patient throughout the range of distances; and

f) examining the display to determine the position of the distal end of the endotracheal tube within the patient.

2. The method of claim 1 wherein said transforming the reflections includes applying a Gopillaud-Ware-Aki algorithmic calculation.

3. The method of claim 1 wherein the distal end of the endotracheal tube at the time of receiving is near the carina and wherein the image includes a length of constant cross-sectional area of the body cavity followed by a length of rapid increase in the area.

7. The method of claim 1 wherein the distal end of the endotracheal tube at the time of the receiving is in the bronchus and wherein the image includes a length of constant cross-sectional area of the body cavity, followed by a length of a moderate decrease of approximately 50 % or more of the total area on the area-distance profile relative to an area image when the endotracheal tube is in the trachea.

8. The method of claim 7 further comprising at least partially removing the endotracheal tube from the bronchus, and re-inserting the endotracheal tube in the trachea to the area above and near the carina.

9. The method of claim 1 further comprising connecting the endotracheal tube and the wavetube with a connecting adapter.

10. The method of claim 9 wherein the endotracheal tube has an endotracheal tube adapter on one end and the connecting adapter is frictionally fitted onto the endotracheal tube adapter.

11. The method of claim 10 wherein said sound waves include acoustic pulses less than two milliseconds in length.

12. The method of claim 1 wherein said sound waves include a series of pulses.

13. The method of claim 1 wherein said sound waves include a series of reflected pulses and wherein said transforming includes averaging the reflected series of pulses.

14. The method of claim 1 wherein said sending sound waves includes delivering the sound waves via a loudspeaker.

15. The method of claim 1 wherein a single microphone is used for said receiving reflections of the sound waves.

16. The method of claim 1 wherein two microphones are used for said receiving reflections of the sound waves.

17. The method of claim 1 further comprising disposing of the wavetube after using the wavetube with just one patient.

18. The method of claim 1 further comprising disposing of the endotracheal tube after using the endotracheal tube with just one patient.

19. The method of claim 1 wherein a sound receiver is used during said receiving and further comprising disposing of the sound receiver after using the sound receiver with just one patient.

20. The method of claim 1 further comprising ventilating the patient through the wavetube and the endotracheal tube.

21. The method of claim 1 wherein the endotracheal tube and the wavetube are a single tube.

22. The method of claim 21 further comprising ventilating the patient through the single tube.

4. The method of claim I wherein the distal end of the endotracheal tube at the time of the receiving is in the esophagus and wherein the image includes a length of constant cross-sectional area of the body cavity followed by a length with a decrease in the area to approximately zero.

5. The method of claim 4 further comprising at least partially removing the endotracheal tube after said examining and re-inserting the endotracheal tube in the trachea.

6. The method of claim 4 further comprising delivering oxygen through the endotracheal tube after determining proper positioning of the endotracheal tube in the patient.

23. An instrument for performing an endotracheal intubation in a patient comprising:

a) an endotracheal tube having a proximal and a distal end, wherein the distal end is inserted through the mouth or nose of a patient;

b) a wavetube for acoustic communication with said endotracheal tube;

c) a sound generator for generating sound for delivery through said wave tube and said endotracheal tube;

d) a sound receiver for receiving reflections of the sound within the wavetube and the body cavity;

e) a processor in communication with said sound receiver for transforming the reflections into data representative of the cross-sectional area of the body cavity in the patient throughout a range of distances beyond the distal end of the endotracheal tube; and

f) a display in communication with said processor for displaying an image of the cross-sectional area of the body cavity in the patient throughout the range of distances.

24. The instrument of claim 23 wherein said wavetube is made of silicon.

25. The instrument of claim 23 wherein said sound generator includes a loudspeaker.

26. The instrument of claim 23 wherein said sound receiver includes only one microphone.

27. The instrument of claim 26 wherein said microphone is hermetically-sealed.

28. The instrument of claim 23 wherein said sound receiver includes two microphones.

30. The instrument of claim 28 wherein said microphones are hermetically-sealed.

32. The instrument of claim 23 further comprising a connecting adapter for connecting said wavetube to said endotracheal tube.

33. The instrument of claim 32 wherein said endotracheal tube has an endotracheal tube adapter on one end and said connecting adapter is frictionally fitted onto said endotracheal tube adapter.

34. The instrument of claim 23 wherein said display is attached to said wavetube in a manner that is easy for the user to detach.

35. The instrument of claim 23 further comprising a battery for providing power.

36. The instrument of claim 23 wherein said wavetube has an internal diameter of approximately 7.0-7.5 mm and is adapted for imaging a body cavity in an adult human patient.

37. The instrument of claim 23 wherein said wavetube has an internal diameter of approximately 3.0-3.5 mm and is adapted for imaging a body cavity in a pediatric human patient.

38. The instrument of claim 23 wherein said wavetube has an inner cross-sectional area of no more than 0.5 square centimeters and is adapted for imaging an area in an adult human patient.

39. The instrument of claim 23 wherein said wavetube has an inner cross-sectional area of no less than 0.07 square centimeters and is adapted for imaging an area in a pediatric human patient.

40. The instrument of claim 23 wherein said wavetube is coiled.

41. The instrument of claim 40 wherein said wavetube is coiled in a helical configuration.

42. The instrument of claim 40 wherein said wavetube is coiled in a serpentine configuration.

43. The instrument of claim 23 wherein said endotracheal tube and said wavetube are a single tube.

44. Apparatus for use with an acoustic reflectometer comprising:

a) a coiled wavetube for communicating acoustic signals;

b) a sound generator in communication with said coiled wavetube for generating sound waves in said coiled wavetube; and

c) a sound receiver in communication with said coiled wavetube for receiving reflections of the sound waves within said coiled wavetube.

45. The apparatus of claim 44 wherein said sound generator includes a loudspeaker.

46. The apparatus of claim 44 wherein said sound receiver includes only one microphone.

47. The apparatus of claim 44 wherein said sound receiver includes two microphones.

48. The apparatus of claim 44 further comprising a processing system in communication with said sound receiver for processing the reflected sound.

49. The apparatus of claim 44 further comprising a display in communication with said processing system.

50. The apparatus of claim 44 wherein said coiled wavetube has a proximal end and wherein said display is positioned adjacent to said proximal said end.

51. The apparatus of claim 44 further comprising a battery for providing power.

52. The apparatus of claim 51 wherein said coiled wavetube, sound generator, sound receiver, processing system, display and battery are encased together.

53. The apparatus of claim 44 wherein said coiled wavetube is substantially helical in shape.

54. The apparatus of claim 44 wherein said coiled wavetube is substantially serpentine in shape.

55. The apparatus of claim 44 wherein said coiled wavetube has a distal end configured to attach to an endotracheal tube.

56. The apparatus of claim 44 wherein said coiled wavetube has a distal end that is integral to an endotracheal tube.

57. A wavetube for an acoustic reflectometer comprising a tube for conducting sound waves within it that is shaped in a coil.

58. An integrated and miniaturized acoustic reflectometer comprising:

a) a wavetube having a proximal and a distal end;

b) a sound generator in acoustic communication with said wavetube;

c) a sound receiver in acoustic communication with said wavetube;

d) a microprocessor-based processing system in communication with said sound receiver; and

e) a display in communication with said processing system,

f) wherein said wavetube, sound generator, sound receiver, processing system and display form an integral unit.

59. The relectometer of claim 58 wherein said display is adjacent to the proximal end of said wavetube.

60. The relectometer of claim 58 wherein said sound receiver includes a microphone attached to said wavetube.

61. The relectometer of claim 58 wherein said wavetube is coiled.

62. The relectometer of claim 61 wherein said wavetube is coiled in a serpentine configuration.

63. The reflectometer of claim 61 wherein said wavetube is coiled in a helical configuration.

64. The reflectometer of claim 58 wherein said processing system and said display are configured to cause the display of an image representative of the cross-sectional area of the surroundings throughout a range of distances beyond the distal end of said wavetube.

65. The reflectometer of claim 58 further comprising a battery within said integral unit for providing power.

66. Apparatus for use in an acoustic reflectometer comprising:

a) a wavetube;

b) a microphone attached to said wavetube; and

c) a hermetic seal on said microphone to protect said microphone.