Non-invasive, miniature, breath monitoring apparatus

• US 6,599,253 B1
• Filed: 06/25/2001
• Issued: 07/29/2003
• Est. Priority Date: 06/25/2001
• Status: Expired due to Term

• Current Assignee: Oak Crest Institute Of Science
• Original Assignee: Oak Crest Institute Of Science
• Inventors: Baum, Marc M., Lord, Harry C.
• Primary Examiner(s): Look; Edward K.
• Assistant Examiner(s): Fristoe, Jr.; John K
• Application Number:
  US09/891,106
• Time in Patent Office: 764 Days
• Field of Search: 600/528,532 73/23.3 422/84 356/302,303,319,326
• US Class Current: 600/532
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/0813 Measurement of pulmonary parameters by tracers, e.g. radioactive tracers
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: G01N 2021/3129 Determining multicomponents by multiwavelength light
• CPC Class Codes: G01N 2021/3137 with selection of wavelengths after the sample
• CPC Class Codes: G01N 2021/3166 using separate detectors and filters
• CPC Class Codes: G01N 2021/398 CO2 laser
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath

Abstract

A rugged, miniature, spectroscopic gas analyzer apparatus for rapid, non-invasive, multi-component breath monitoring and analysis and subsequent determination of Q or other medical diagnostic applications. The system is comprised of one or more IR emitters focussed by optical elements through a low volume sample cell receiving a sample input of a patient'"'"'s breath for analysis. The patient either at rest or during exercise, inhales C₂H₂—SF₆ mixtures (balance of oxygen and nitrogen) which is subsequently monitored upon exhalation for CO₂, H₂O, C₂H₂, and SF₆ which can be employed to determine Q directly and accurately. Measurements are performed in real-time or via post-processing of stored original data. Due to its small size, ruggedness, and low power consumption, the monitor can conveniently be employed in the field or data can also be retrieved remotely using telemetry. The miniature analyzer operates on the principle of infrared absorption spectroscopy and allows very precise concentration measurements of the analytes of interest, without any bias or interference from other matrix components.

Claims

1. A method of monitoring a subject'"'"'s breath for diagnostic analysis comprising;

delivering a sample gas mixture to a subject;

collecting a low volume breath sample from said subject;

delivering said low volume breath sample from said subject to a miniature sample cell;

projecting one or more collimated beams of radiation through said miniature sample cell;

isolating a narrow spectral region corresponding to at least two selected frequency components centered at different wavelengths;

analyzing said selected frequency components of said collimated beam with one or more spectrometers;

storing each output from said one or more spectrometers;

converting said outputs from each spectrometer to concentration readings;

whereby said outputs can be processed to produce diagnostic information.

2. The method according to claim 1 in which said gas mixture is a mixture of C₂H₂ and SF₆ balance of oxygen and nitrogen.

3. The method according to claim 2 in which said step of analyzing selected frequency component comprises isolating the spectral windows corresponding to an absorption signature of predetermined target gases;

and continuously monitoring the amount of radiation passing through said cell.

4. The method according to claim 3 in which said step of isolating said spectral windows comprises passing said beam through a plurality of narrow bandpass optical filters.

5. The method according to claim 3 in which said plurality of narrow bandpass optical filters comprises four narrow bandpass optical filters for isolating spectral windows of at least three gases.

6. The method according to claim 5 in which said at least three gases are selected from the group consisting of CO₂, H₂O, SF₆, CH₄, C₂H₂, N₂O and CO.

7. The method according to claim 6 including a reference channel spectrometer having a reference gas.

8. The method according to claim 6 in which said at least three gases comprise CO₂, SF₆, and C₂H₂.

9. The method according to claim 6 in which said at least three gases comprise CO₂, CH₄, and N₂O.

10. The method according to claim 6 in which said at least three gases comprise CO₂, CH₄, and CO.

11. The method according to claim 2 in which said gas mixture includes O₂.

12. The method according to claim 1 in which said exhaled sample from said subject is a low volume sample.

13. The method according to claim 12 in which said low volume sample is less than about 1.25 mL.

14. The method according to claim 1 in which said collimated beam is a collimated beam of IR radiation.

15. The method according to claim 14 including modulating said IR radiation at a frequency to produce a rapid response time.

16. The method according to claim 15 in which said IR radiation is modulated at a frequency greater than 50 Hz.

17. The method according to claim 16 in which said IR radiation is modulated at a frequency of approximately 2000 Hz.

18. The method according to claim 14 in which said IR radiation is combined radiation from a plurality of emitters.

19. The method according to claim 18 in which said IR radiation is combined radiation from two emitters.

20. The method according to claim 19 in which said two emitters comprise a CO₂ laser and a broadband thermal element.

21. The method according to claim 1 in which said sample cell is a light tube.

22. The method according to claim 1 in which said step of collecting an exhaled sample from said subject comprises filling an anesthetic bag with said sample gas mixture;

connecting said anesthetic bag to a flow control valve;

placing a breathing tube with said valve in the mouth of a subject; and

connecting said breathing tube to said miniature sample cell.

23. The method according to claim 22 in which said flow control valve connects said subject to said container to rebreathe said mixture of gases.

24. The method according to claim 22 in which said flow control valve connects said subject to said container to inhale said mixture of gases from said container and exhale to said sample cell and ambient air.

25. The method according to claim 22 in which said sample cell is integral with said breathing tube for in situ monitoring.

26. The method according to claim 1 including filtering spectral interferences from said analyzer.

27. The method according to claim 26 in which said step of filter spectral interferences comprises inserting an optical chamber downstream from said sample cell;

filling said optical chamber with a gas having the spectral interference to be removed.

28. The method according to claim 27 in which said optical cell is filled with water vapor.

29. The method according to claim 27 in which said optical cell is filled with carbon dioxide.

30. The method according to claim 1 in which said subject rebreathes said sample gas mixture.

31. The method according to claim 1 in which said subject breathes said sample gas mixture and exhales to said sample cell and ambient air.

32. The method according to claim 6 including a reference channel spectrometer.

33. A method of monitoring a subject'"'"'s breath for diagnostic analysis comprising;

delivering a sample gas mixture to a subject;

collecting a breath sample from said subject;

delivering said breath sample from said subject to a miniature sample cell;

projecting collimated beams of IR radiation from a CO₂ laser and a broadband thermal element through said miniature sample cell;

analyzing selected frequency components of said collimated beam with one or more spectrometers;

storing each output from said one or more spectrometers;

converting said outputs from each spectrometer to concentration readings;

whereby said outputs can be processed to produce diagnostic information.

34. A method of monitoring a subject'"'"'s breath for diagnostic analysis comprising;

delivering a sample gas mixture to a subject;

collecting a breath sample from said subject;

delivering said breath sample from said subject to a miniature light pipe sample cell;

projecting one or more collimated beams of radiation through said miniature sample cell;

analyzing selected frequency components of said collimated beam with one or more spectrometers;

storing each output from said one or more spectrometers;

converting said outputs from each spectrometer to concentration readings;

whereby said outputs can be processed to produce diagnostic information.

35. A method of monitoring a subject'"'"'s breath for diagnostic analysis comprising;

delivering a sample gas mixture to a subject;

collecting a breath sample from said subject;

said step of collecting a breath sample from said subject comprises filling an anesthetic bag with said sample gas mixture, connecting said anesthetic bag to a flow control valve, placing a breathing tube with said valve in the mouth of a subject, and connecting said breathing tube to said miniature sample cell;

delivering said breath sample from said subject to a miniature sample cell;

projecting one or more collimated beams of radiation through said miniature sample cell;

analyzing selected frequency components of said collimated beam with one or more spectrometers;

storing each output from said one or more spectrometers;

converting said outputs from each spectrometer to concentration readings;

whereby said outputs can be processed to produce diagnostic information.

36. The method according to claim 35 in which said flow control valve connects said subject to said container to rebreathe said mixture of gases.

37. The method according to claim 35 in which said flow control valve connects said subject to said container to inhale said mixture of gases from said container and exhale to said sample cell and ambient air.

38. The method according to claim 35 in which said sample cell is integral with said breathing tube for in situ monitoring.

39. A method of monitoring a subject'"'"'s breath for diagnostic analysis comprising;

delivering a sample gas mixture to a subject;

collecting a breath sample from said subject;

delivering said breath sample from said subject to a miniature sample cell;

projecting one or more collimated beams of radiation through said miniature sample cell;

filtering spectral interferences from said analysis by inserting an optical chamber downstream from said miniature sample cell, filling said optical chamber with a gas having the spectral interference to be filtered;

analyzing selected frequency components of said collimated beam with one or more spectrometers;

storing each output from said one or more spectrometers;

converting said outputs from each spectrometer to concentration readings;

whereby said outputs can be processed to produce diagnostic information.

40. The method according to claim 39 in which said optical cell is filled with water vapor.

41. The method according to claim 39 in which said optical cell is filled with carbon dioxide.

42. A method of monitoring a subject'"'"'s breath for diagnostic analysis comprising;

delivering a sample gas mixture to a subject, said subject rebreathing said sample gas mixture;

collecting a breath sample from said subject;

delivering said breath sample from said subject to a miniature sample cell;

projecting one or more collimated beams of radiation through said miniature sample cell;

analyzing selected frequency components of said collimated beam with one or more spectrometers;

storing each output from said one or more spectrometers;

converting said outputs from each spectrometer to concentration readings;

whereby said outputs can be processed to produce diagnostic information.