Acoustic detection of endotracheal tube location

• US 8,394,031 B2
• Filed: 07/01/2002
• Issued: 03/12/2013
• Est. Priority Date: 10/06/2000
• Status: Expired due to Fees

• Current Assignee: Biomedical Acoustic Research Corporation
• Original Assignee: Biomedical Acoustic Research Corporation
• Inventors: Mansy, Hansen A., Sandler, Richard H.
• Primary Examiner(s): TOWA, RENE T
• Application Number:
  US10/186,763
• Publication Number:
  US 20030018276A1
• Time in Patent Office: 3,907 Days
• Field of Search: 600/532, 600/513, 600/586, 600/550, 600508-509, 600528-529, 381/67, 381/92
• US Class Current: 600/550
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

A system and method for use in detecting an endotracheal tube location within a body electronically detects indigenous breath sounds emanating from a region of the body and processes the detected indigenous breath sounds to generate a parameter representative of an acoustic characteristic of the body associated with the endotracheal tube location within the body. The system and method generates an output indicative of the endotracheal tube location within the body based on the parameter representative of the acoustic characteristic of the body.

Claims

1. A method of detecting an endotracheal tube location within a body, the method comprising:

electronically detecting indigenous breath sounds emanating from the body, including receiving a first signal from a first acoustic sensor at a first location of the body and a second signal from a second acoustic sensor at a second location of the body;

electronically processing the detected indigenous breath sounds to calculate a first acoustic energy corresponding to the first location using the first signal and a second acoustic energy corresponding to the second location using the second signal, wherein each of the acoustic energies corresponds to substantially the same time interval;

calculating an acoustic energy ratio of the first and second acoustic energies, wherein the acoustic energy ratio is representative of an acoustic characteristic of the body associated with the endotracheal tube location within the body; and

electronically generating an output indicative of the endotracheal tube location within the body based on the acoustic energy ratio.

2. The method of claim 1, wherein at least one of the first acoustic sensor or the second acoustic sensor is disposed adjacent to one of a chest region of the body or an epigastric region of the body.

3. The method of claim 1, wherein the first acoustic sensor is disposed adjacent to a left side chest region of the body and the second acoustic sensor is disposed adjacent to a right side chest region of the body.

4. The method of claim 1, wherein the acoustic energy ratio is a spectral energy ratio.

5. The method of claim 4, wherein calculating the spectral energy ratio includes converting the detected indigenous breath sounds into digital information and using a fast Fourier transform to calculate the spectral energy ratio.

6. The method of claim 4, wherein calculating the spectral energy ratio includes dividing a first spectral energy value associated with a chest region of the body by a second spectral energy value associated with an epigastric region of the body.

7. The method of claim 1, wherein electronically processing the detected indigenous breath sounds further comprises calculating one of a mean spectral difference or a time delay.

8. The method of claim 1, wherein electronically generating the output indicative of the endotracheal tube location within the body based on the acoustic energy ratio includes comparing the acoustic energy ratio to a baseline value associated with a non-intubated condition of the body.

9. The method of claim 1, wherein electronically generating the output indicative of the endotracheal tube location within the body based on the acoustic energy ratio representative of the acoustic characteristic of the body includes generating one of a visual or an audible indication of the endotracheal tube location.

10. The method of claim 1, wherein electronically generating the output indicative of the endotracheal tube location within the body based on the acoustic energy ratio representative of the acoustic characteristic of the body includes generating an output indicative of one of a tracheal location, an esophageal location or a mainstem location.

11. The method of claim 1, further including electronically detecting ventilation cycle timing information of the body and using the ventilation cycle timing information to process the detected indigenous breath sounds.

12. The method of claim 1, wherein electronically processing the detected indigenous breath sounds to calculate the acoustic energy ratio representative of the acoustic characteristic of the body associated with the endotracheal tube location within the body includes discarding data associated with a portion of the detected indigenous breath sounds having a low signal-to-noise ratio.

13. The method of claim 12, wherein discarding data associated with the portion of the detected indigenous breath sounds having a low signal-to-noise ratio includes discarding the data based on a predetermined threshold value.

14. The method of claim 1, wherein electronically detecting the indigenous breath sounds emanating from the body includes detecting indigenous breath sounds emanating from an epigastric region of the body.

15. The method of claim 14, wherein electronically processing the detected indigenous breath sounds to calculate the acoustic energy ratio representative of the acoustic characteristic of the body associated with the endotracheal tube location within the body includes calculating a temporal characteristic of the indigenous breath sounds emanating from the epigastric region of the body.

16. The method of claim 15, wherein electronically generating the output indicative of the endotracheal tube location within the body based on the acoustic energy ratio representative of the acoustic characteristic of the body includes generating an output indicative of an esophageal location of the endotracheal tube within the body based on the temporal characteristic of the indigenous breath sounds emanating from the epigastric region of the body.

17. The method of claim 1, wherein electronically detecting the indigenous breath sounds emanating from the body includes electronically detecting indigenous breath sounds associated with a left chest region of the body and detecting indigenous breath sounds associated with a right chest region of the body.

18. The method of claim 17, wherein electronically processing the detected indigenous breath sounds includes calculating a time delay between the indigenous breath sounds associated with the left chest region and the indigenous breath sounds associated with the right chest region.

19. The method of claim 18, wherein electronically generating the output indicative of the endotracheal tube location within the body includes generating an output indicative of a mainstem location of the endotracheal tube within the body based on the time delay between the indigenous breath sounds associated with the left chest region and the indigenous breath sounds associated with the right chest region.

20. The method of claim 1, further including generating a low signal level indication in response to a determination that the detected indigenous breath sounds are below a predetermined threshold value.

21. The method of claim 1, further including generating a baseline value for comparison to the acoustic energy ratio representative of the acoustic characteristic.

22. The method of claim 21, wherein generating the baseline value includes generating the baseline value based on one of historical breath sounds data, a mask-ventilated condition of the body, or a tracheally intubated condition of the body.

23. The method of claim 1, wherein electronically processing the detected indigenous sounds to calculate the acoustic energy ratio representative of the acoustic characteristic of the body includes using an adaptive filtering technique to filter noise.

24. The method of claim 1, wherein the first signal received from the first sensor and the second signal received from the second sensor are in the same frequency band.

25. A system for use in detecting an endotracheal tube location within a body, the system comprising:

a first acoustic sensor to electronically detect indigenous breath sounds emanating from a first location of the body;

a second acoustic sensor to electronically detect indigenous breath sounds emanating from a second location of the body;

a processing unit to receive a first signal from the first acoustic sensor and a second signal from the second acoustic sensor and to electronically process the first signal and the second signal to calculate a first acoustic energy corresponding to the first location using the first signal and a second acoustic energy corresponding to the second location using the second signal, wherein each of the acoustic energies corresponds to substantially the same time interval and to calculate an acoustic energy ratio based on the first and second acoustic energies, wherein the acoustic energy ratio is representative of an acoustic characteristic of the body associated with the endotracheal tube location within the body; and

an output device to electronically generate an output indicative of the endotracheal tube location within the body based on the acoustic energy ratio.

26. The system of claim 25, wherein at least one of the first acoustic sensor or the second acoustic sensor is to be disposed adjacent one of a chest region of the body or an epigastric region of the body.

27. The system of claim 25, wherein the first acoustic sensor is to be disposed adjacent to a left side chest region of the body and the second acoustic sensor is to be disposed adjacent to a right side chest region of the body.

28. The system of claim 25, wherein the acoustic energy ratio is a spectral energy ratio.

29. The system of claim 28, wherein the processing unit is to calculate the spectral energy ratio by converting the first signal and the second signal into digital information and using a fast Fourier transform to convert the digital information into spectral information.

30. The system of claim 28, wherein the processing unit is to calculate the spectral energy ratio by dividing a first spectral energy value associated with a chest region of the body by a second spectral energy value associated with an epigastric region of the body.

31. The system of claim 25, wherein the processing unit is to further calculate one of a mean spectral difference or a time delay.

32. The system of claim 25, wherein the output indicative of the endotracheal tube location within the body is based on a comparison of the acoustic energy ratio representative of the acoustic characteristic of the body to a baseline value associated with a non-intubated condition of the body.

33. The system of claim 25, wherein the output device is to generate one of a visual or an audible indication of the endotracheal tube location.

34. The system of claim 25, wherein the output device is to generate one of an output indicative of one of a tracheal location, an esophageal location or a mainstem location.

35. The system of claim 25, further including an airflow sensor that is to electronically detect ventilation cycle timing information of the body, and wherein the processing unit is to use the ventilation cycle timing information to process the first signal and the second signal.

36. The system of claim 25, wherein the processing unit is to discard data associated with a portion of the first signal or the second signal having a low signal-to-noise ratio.

37. The system of claim 36, wherein the processing unit is to discard the data based on a predetermined threshold value.

38. The system of claim 25, wherein at least one of the first acoustic sensor or the second acoustic sensor is to electronically detect the indigenous breath sounds emanating from an epigastric region of the body.

39. The system of claim 25, wherein the processing unit is to calculate the acoustic energy ratio representative of the acoustic characteristic of the body associated with the endotracheal tube location within the body by calculating a temporal characteristic of the first signal or the second signal based on the acoustic characteristic.

40. The system of claim 39, wherein the output device is to electronically generate an output indicative of an esophageal location of the endotracheal tube within the body.

41. The system of claim 25, wherein the first acoustic sensor is to detect indigenous breath sounds associated with a left chest region of the body and the second acoustic sensor that is to detect indigenous breath sounds associated with a right chest region of the body.

42. The system of claim 41, wherein the processing unit is to calculate a time delay between the indigenous breath sounds associated with the left chest region and the indigenous breath sounds associated with the right chest region.

43. The system of claim 42, wherein the output device is to electronically generate an output indicative of a mainstem location of the endotracheal tube within the body based on the time delay.

44. The system of claim 25, wherein the output device is to electronically generate a low signal level indication in response to a determination that the first signal second signal is below a predetermined threshold value.

45. The system of claim 25, wherein the processing unit is to generate a baseline value for comparison to the acoustic energy ratio representative of the acoustic characteristic.

46. The system of claim 45, wherein the processing unit is to generate the baseline value by generating the baseline value based on one of historical breath sounds data, a mask-ventilated condition of the body, or a tracheally intubated condition of the body.

47. The system of claim 25, wherein the processing unit is to calculate the acoustic energy ratio representative of the acoustic characteristic of the body using an adaptive filtering technique to filter noise.

48. The system of claim 25, wherein the first signal and the second signal are in the same frequency band.