Methods and systems for quantitative colorimetric capnometry

• US 10,175,254 B2
• Filed: 07/16/2014
• Issued: 01/08/2019
• Est. Priority Date: 07/16/2013
• Status: Active Grant

• Current Assignee: Freespira Incorporated
• Original Assignee: Palo Alto Health Sciences, Inc.
• Inventors: Mace, Leslie E., Siegelman, Elizabeth K., Reisenthel, Debra L., Thomas, Simon W. H.
• Primary Examiner(s): Kuhlman, Catherine B
• Application Number:
  US14/902,075
• Publication Number:
  US 20160245830A1
• Time in Patent Office: 1,637 Days
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/082 Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath A61B5/083, A61B5/091 take precedence
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices
• CPC Class Codes: A61B 5/1032 Determining colour for diagnostic purposes measuring colour in general G01J3/46
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/486 Bio-feedback A61B5/375 takes precedence
• CPC Class Codes: A61B 5/7415 Sound rendering of measured values, e.g. by pitch or volume variation A61B5/741 takes precedence
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 2021/0027 by the hearing sense
• CPC Class Codes: A61M 2021/0088 modulated by a simulated respiratory frequency
• CPC Class Codes: A61M 21/02 for inducing sleep or relaxation, e.g. by direct nerve stimulation, hypnosis, analgesia for massage A61H; electrotherapy A61N, e.g. applying alternating or intermittent electric currents for producing anaesthesia A61N1/36021
• CPC Class Codes: A61M 2205/3303 Using a biosensor
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 2205/582 by tactile feedback
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)
• CPC Class Codes: G01N 2021/7773 Reflection
• CPC Class Codes: G01N 21/3151 : using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence
• CPC Class Codes: G01N 21/78 : producing a change of colour
• CPC Class Codes: G01N 21/783 : for analysing gases
• CPC Class Codes: G01N 2201/0231 : Thermostating
• CPC Class Codes: G01N 2201/062 : LED's
• CPC Class Codes: G01N 2201/1211 : for temperature
• CPC Class Codes: G01N 33/84 : involving inorganic compounds or pH
• CPC Class Codes: G16H 20/30 : relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising
• CPC Class Codes: G16H 20/40 : relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture
• CPC Class Codes: G16H 40/40 : for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: G16H 40/63 : for local operation
• CPC Class Codes: G16H 40/67 : for remote operation
• CPC Class Codes: G16H 50/20 : for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: H04M 1/72412 : using two-way short-range wireless interfaces

Abstract

Quantitative colorimetric carbon dioxide detection and measurement systems are disclosed. The systems can include a gas conduit, a colorimetric indicator adapted to exhibit a color change in response to exposure to carbon dioxide gas, a temperature controller operatively coupled to the colorimetric indicator and configured to control the temperature of the colorimetric indicator, an electro-optical sensor assembly including a light source or sources adapted to transmit light to the colorimetric indicator, and a photodiode or photodiodes configured to detect light reflected from the colorimetric indicator and to generate a measurement signal, and a processor in communication with the electro-optical sensor assembly. The processor can be configured to receive the measurement signal generated by the electro-optical sensor assembly and to compute a concentration of carbon dioxide based on the measurement signal. Methods for using the systems are also disclosed including providing a breathing therapy to a patient or user.

Claims

1. A quantitative colorimetric carbon dioxide detection and measurement system comprising:

a gas conduit;

a colorimetric indicator adapted to exhibit a color change in response to exposure to carbon dioxide gas;

a temperature sensor configured to measure a temperature of the colorimetric indicator;

an electro-optical sensor assembly comprising a light source or sources adapted to transmit light to the colorimetric indicator, and a light detection element configured to detect light reflected from the colorimetric indicator and to generate a measurement signal;

a processor in communication with the electro-optical sensor assembly, the processor configured to;

receive the measurement signal generated by the electro-optical sensor assembly and the temperature of the colorimetric indicator, and

compute a concentration of carbon dioxide based on the measurement signal and the temperature of the colorimetric indicator; and

a device configured to electronically receive the computed carbon dioxide concentration and execute a breathing therapy program comprising a set of tone patterns adapted for guiding a user'"'"'s breathing technique to modulate the carbon dioxide to a level between about 37 mmHg and 43 mmHg.

2. The system of claim 1, wherein the processer is further configured to compute a respiration rate based on the measurement signal, and wherein the device is further configured to electronically receive the computed respiration rate.

3. The system of claim 2, wherein the device comprises a display, wherein the processor is configured to transmit the computed concentration of carbon dioxide and Respiration Rate to the display and the display is configured to display the computed concentration of carbon dioxide and Respiration Rate.

4. The system of claim 2, wherein the processor is further configured to apply a temperature correction to the measurement signal based on the temperature of the colorimetric indicator.

5. The system of claim 1, wherein the processor is within a housing of the quantitative colorimetric carbon dioxide detection and measurement system.

6. The system of claim 1, wherein the system comprises a display, wherein the processor is further configured to transmit the measurement signal to the device and the device is configured to compute a concentration of the carbon dioxide and a respiration rate based on the measurement signal.

7. The system of claim 6, wherein the system is configured to display a target respiratory rate and a target carbon dioxide level.

8. The system of claim 7, wherein the system is configured to measure and display a baseline level of the user'"'"'s respiratory rate and carbon dioxide level before any tone patterns are generated.

9. The system of claim 1, further comprising a pump configured to move a sample of gas in the gas conduit into contact with the colorimetric indicator.

10. The system of claim 9, wherein the pump is upstream of the colorimetric indicator.

11. The system of claim 9, wherein the pump is downstream of the colorimetric indicator.

12. The system of claim 1, wherein the gas conduit includes a separate disposable tube containing the colorimetric indicator, the disposable tube configured to removably engage with and couple to the electro-optical sensor assembly.

13. The system of claim 1, further comprising a display in communication with the processor, the display configured to display a user interface for operating the system.

14. The system of claim 1, further comprising a sensor cable coupling the electro-optical sensor assembly to the processor.

15. The system of claim 1, wherein the system is wearable.

16. The system of claim 1, wherein the system is configured to measure a user'"'"'s exhaled air during breathing.

17. The system of claim 16, wherein the processor is configured to provide a guided breathing maneuver to thereby alter the amount of carbon dioxide measured from a user'"'"'s exhaled air.

18. The system of claim 16, wherein the processor is configured to provide visual and/or audio cues to guide the user'"'"'s breathing.

19. The system of claim 16, wherein the processor is configured to provide the user a guided breathing maneuver based on the quantity of carbon dioxide measured from the user'"'"'s exhaled breath.

20. The system of claim 16, wherein the processor is configured to provide the user a guided breathing maneuver based on a respiration rate measured from the user'"'"'s exhaled breath.

21. The system of claim 1, further comprising a nasal and/or oral cannula adapted for collecting a sample of a user'"'"'s exhaled breath for exhaled carbon dioxide measurement, wherein the cannula is configured to be in fluid communication with the gas conduit.

22. The system of claim 1, wherein the gas conduit includes a nasal and/or oral cannula adapted for collecting a sample of a user'"'"'s exhaled breath for exhaled carbon dioxide measurement.

23. The system of claim 22, wherein the gas conduit includes the colorimetric indicator and nasal and/or oral cannula, wherein the gas conduit, colorimetric indicator, and nasal and/or oral cannula are configured for a single use.

24. The system of claim 1, wherein the processor is configured to measure a respiration rate.

25. The system of claim 1, wherein the tone patterns correspond to a total breath time, an inhalation time, an expiration time, a first pause time between inhalation to exhalation, and a second pause time between exhalation and inhalation.

26. The system of claim 25, wherein the tone patterns provide silence for the first and second pause times.

27. The system of claim 1, wherein the device is configured to record the user'"'"'s information.

28. The system of claim 1, wherein the device is configured to visually display a goal line corresponding to a target end-tidal CO₂ level on an end-tidal CO₂ graph.

29. The system of claim 1, wherein the device is a mobile device.

30. The system of claim 1, wherein the electro-optical assembly includes one photodiode and two alternating light sources.

31. The system of claim 1, wherein the electro-optical assembly includes two photodiodes and two light sources.

32. The device of claim 1, further comprising a temperature controller operatively coupled to the colorimetric indicator and configured to control the temperature of the colorimetric indicator.

33. The system of claim 32, wherein the processor is configured to control the temperature controller to maintain the colorimetric indicator at a pre-determined temperature.

34. The system of claim 33, wherein the pre-determined temperature is from 20°

C. to about 50°

C.

35. The system of claim 32, wherein the temperature controller is further configured to control a temperature of the electro-optical sensor.

36. The system of claim 32, wherein the temperature controller includes a heater.

37. The system of claim 1 wherein the light detection element includes a photodiode or photodiodes.

38. The system of claim 1, wherein the device is a mobile display device.

39. The system of claim 1, further comprising a pressure sensor configured to measure a pressure of a gas sample, wherein the processor is configured to receive the pressure measurement and to compute a concentration of carbon dioxide based on the measurement signal and the temperature of the colorimetric indicator and the pressure of the gas sample.

40. A quantitative colorimetric carbon dioxide detection system comprising:

a colorimetric indicator adapted to change color in response to exposure to a quantity of carbon dioxide gas;

a temperature sensor configured to measure a temperature of the colorimetric indicator;

an electro-optical sensor assembly coupled to the colorimetric indicator, the electro-optical sensor assembly comprising light sources adapted to transmit a first wavelength and a second wavelength to the colorimetric indicator, wherein the first wavelength is configured to be sensitive to an indicator color change and the second wavelength is configured to not be as sensitive to an indicator color change, and a light detection element configured to detect a first reflected light based on the first wavelength and a second reflected light based on the second wavelength, and to generate a first electrical signal based on the first reflected light and a second electrical signal based on the second reflected light;

a processor in communication with the electro-optical sensor assembly and temperature sensor, the processor configured to receive the electrical signals generated by the electro-optical sensor assembly to compute the concentration of carbon dioxide exposed to the indicator; and

a device configured to electronically receive the computed carbon dioxide concentration and execute a breathing therapy program comprising a set of tone patterns adapted for guiding a user'"'"'s breathing technique to modulate the carbon dioxide to a level between about 37 mmHg and 43 mmHg.

41. The system of claim 40, wherein the electro-optical sensor assembly is configured to alternately transmit the first and second wavelengths.

42. The device of claim 40, further comprising a temperature controller coupled to the colorimetric indicator and configured to control a temperature of the colorimetric indicator.

43. A method for quantitatively measuring carbon dioxide, the method comprising:

passing a sample gas through a gas conduit;

contacting a colorimetric indicator with the sample gas, the colorimetric indicator adapted to exhibit a color change in response to exposure to carbon dioxide gas;

measuring a temperature of the colorimetric indicator with a temperature sensor while contacting the colorimetric indicator with the sample gas;

transmitting light to the colorimetric indicator with an electro-optical sensor assembly comprising a light source or sources while contacting the colorimetric indicator with the sample gas;

detecting light reflected from the colorimetric indicator with a light detection element;

generating a measurement signal from the light detection element based on the reflected light;

sending the measurement signal to a processor;

computing the concentration of carbon dioxide in the sample gas with the processor based on the measurement signal and the temperature of the colorimetric indicator; and

executing a breathing therapy program comprising a set of tone patterns adapted for guiding a user'"'"'s breathing technique to modulate the carbon dioxide to a level between about 37 mmHg and 43 mmHg.

44. The method of claim 43, wherein computing the concentration of carbon dioxide with the processor is based on the color change of the colorimetric indicator.

45. The method of claim 43, further comprising moving the sample gas in the gas conduit into contact with the colorimetric indicator using a pump.

46. The method of claim 43, further comprising displaying a user interface for operating the system.

47. The method of claim 43, further comprising continuously measuring a user'"'"'s exhaled air during breathing.

48. The method of claim 47, further comprising providing a guided breathing maneuver to the user with instructions to alter the amount of carbon dioxide measured from the user'"'"'s exhaled air.

49. The method of claim 47, further comprising providing visual and/or audio cues to guide the user'"'"'s breathing.

50. The method of claim 43, further comprising measuring the breathing rate of a user'"'"'s breathing.

51. The method of claim 43, further comprising electronically sending the computed CO₂ concentration to a device and executing a breathing therapy program comprising a set of tone patterns for guiding a user'"'"'s breathing pattern while monitoring the user'"'"'s CO₂ levels with the device.

52. The method of claim 51, wherein the device is a mobile device with a display.

53. The method of claim 51, wherein the device includes a display.

54. The method of claim 53, further comprising visually displaying on the device a goal line corresponding to a target end-tidal CO₂ level on an end-tidal CO₂ graph.

55. The method of claim 51, wherein the tone patterns are based on the computed CO₂ levels and a respiration rate that is computed from the measurement signal.

56. The method of claim 51, wherein the tone patterns correspond to a total breath time, an inhalation time, an expiration time, a first pause time between inhalation to exhalation, and a second pause time between exhalation and inhalation.

57. The method of claim 56, wherein the tone patterns provide silence for the first and second pause times.

58. The method of claim 51, further comprising recording the user'"'"'s information with the device.

59. The method of claim 43 further comprising controlling the temperature of the colorimetric indicator with a temperature controller coupled to the colorimetric indicator while contacting the colorimetric indicator with the sample gas.

60. The method of claim 59, further comprising maintaining the colorimetric indicator at a pre-determined temperature with the temperature controller.

61. The method of claim 60, wherein the pre-determined temperature is from about 20°

C. to about 50°

C.

62. The method of claim 43, further comprising:

measuring a pressure of the sample gas;

sending the pressure measurement to the processor; and

computing the concentration of carbon dioxide in the sample gas with the processor based on the measurement signal and the temperature of the colorimetric indicator and the pressure of the sample gas.