Capnograph system with integral controller

• US 20040236242A1
• Filed: 05/22/2003
• Published: 11/25/2004
• Est. Priority Date: 05/22/2003
• Status: Abandoned Application

• Current Assignee: Perkinelmer Incorporated
• Original Assignee: Perkinelmer Incorporated
• Inventors: Graham, James E., OʼLeary, Robert K., Witz, Dennis, Vidal, David
• Application Number:
  US10/443,696
• Publication Number:
  US 20040236242A1
• Time in Patent Office: Days
• US Class Current: 600/532
• 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

Abstract

A capnograph system sensor head includes an airway adapter, a housing for receiving the airway adapter, a source of infrared radiation coupled to the housing for directing infrared radiation through the airway adapter, and a detector subsystem coupled to the housing and responsive to the infrared radiation after it passes through the airway adapter for providing an analog output. A circuit sub-assembly is integrated with the sensor head and includes a controller responsive to the analog output of the detector subsystem. The controller is configured to adjust the gain of the detector subsystem to output a digital signal representative of the amount of a particular gas flowing through the airway adapter.

Claims

1. A capnograph system sensor head comprising:

an airway adapter;

a housing for receiving the airway adapter;

a source of radiation coupled to the housing for directing radiation through the airway adapter;

a detector subsystem coupled to the housing and responsive to the radiation after it passes through the airway adapter for providing an analog output; and

a circuit sub-assembly integrated with the sensor head, the circuit sub-assembly including a controller responsive to the analog output of the detector subsystem, the controller configured to adjust the gain of the detector subsystem and configured to output a digital signal representative of the amount of a particular gas flowing through the airway adapter.

2. The sensor head of claim 1 in which the integrated circuit sub-assembly is disposed on a flex circuit folded and received by the housing.

3. The sensor head of claim 1 in which the controller is programmed to adjust the optical output level of the source in response to the output level of the detector subsystem.

4. The sensor head of claim 3 in which the circuit subassembly further includes an amplifier connected between the controller and the source.

5. The sensor head of claim 4 in which the amplifier is a field effect transistor.

6. The sensor head of claim 1 in which the controller is programmed to amplify the output of the detector subsystem in response to the output level of the detector subsystem.

7. The sensor head of claim 6 in which the detector subsystem includes an amplification circuit responsive to the controller.

8. The sensor head of claim 1 in which the controller is programmed, in response to the output level of the detector subsystem, to both adjust the optical output level of the source and to amplify the output level of the detector subsystem.

9. The sensor head of claim 1 further including a cable connected on one end to the housing for transmitting the digital signal.

10. The sensor head of claim 9 in which the circuit subassembly further includes a communications chip connected between the controller and the cable.

11. The sensor head of claim 10 in which the communications chip is configured to convert a TTL signal output by the controller to a compatible digital signal.

12. The sensor head of claim 9 in which the cable includes a distal connector.

13. The sensor head of claim 1 in which the circuit subassembly further includes a memory having calibration coefficients for the source and the detector subsystem stored therein.

14. The sensor head of claim 13 in which the memory is an EE PROM.

15. The sensor head of claim 1 in which the circuit subassembly further includes a voltage regulation circuit configured to provide a reference voltage and to protect the circuit subassembly against over voltage conditions.

16. The sensor head of claim 1 in which the circuit subassembly further includes a logic circuit connected between the detector subsystem and the controller.

17. The sensor head of claim 16 in which the logic circuit includes a channel responsive to a reference sensor of the detector subsystem and a channel responsive to the sample sensor of the detection subsystem.

18. The sensor head of claim 17 in which the controller includes a processor responsive to both channels.

19. The sensor head of claim 17 in which the controller includes an analog-to-digital converter.

20. The sensor head of claim 1 in which the detector subsystem includes:

a sample sensor,

a reference sensor, and

an integrating lens positioned to integrate collimated radiation passing through the airway adapter evenly over the sample sensor and the reference sensor so that the instantaneous field of view of the sample sensor and the reference sensor are the same to equalize any obscuration effects thereof.

21. The sensor head of claim 1 in which the source includes:

a radiation source; and

a collimating lens which forms a collimated beam.

22. The sensor head of claim 21 in which the collimating lens is positioned at a distance from the radiation source such that the radiation source is completely imaged by the collimating lens.

23. The sensor head of claim 22 in which the collimating lens has a focal length greater than the distance between the collimating lens and the radiation source.

24. The sensor head of claim 21 in which the radiation source is an infrared radiation producing filament.

25. The sensor head of claim 21 in which the collimating lens is one half of a ball lens, the flat surface of which faces the radiation source.

26. The sensor head of claim 25 in which the collimating lens is made of sapphire.

27. The sensor head of claim 20 in which the integrating lens is positioned at a distance from the sample sensor and the reference sensor such that the sample sensor and the reference sensor are both completely imaged by the integrating lens.

28. The sensor head of claim 27 in which the integrating lens has a focal length greater than the distance between the integrated lens and the sample and reference sensors.

29. The sensor head of claim 20 in which the integrating lens is one half of a ball lens, the flat surface of which faces the sample and reference detectors.

30. The sensor head of claim 29 in which the integrating lens is made of sapphire.

31. The sensor head of claim 1 in which the source includes a TO header, a filament supported above the header, a TO can mated with the TO header and including an aperture therein, and a collimating lens positioned in the can between the filament and the aperture.

32. The sensor head of claim 1 in which the detector subsystem includes a TO header having a reference sensor and a sample sensor mounted thereon adjacent each other, a filter pack above the reference and sample sensors, and a TO can mounted with the header and including an aperture therein, and an integrating lens positioned in the TO can between the aperture therein and the filter pack.

33. The sensor head of claim 1 in which the source includes a header, a filament supported above the header, a can mated with the header and including an aperture therein, and a collimating lens positioned in the can between the filament and the aperture which outputs a collimated beam of radiation across the airway adapter and wherein the detector subsystem includes a header having a reference sensor and a sample sensor mounted thereon adjacent each other, a filter pack above the reference sensor and sample sensors, a TO can mounted with the header and including an aperture therein, and an integrating lens positioned in the TO can between the aperture therein and the filter pack to integrate the collimated radiation passing through the airway adapter evenly over the sample sensor and the reference sensor so that the instantaneous fields of view of the sample sensor and the reference sensor are the same to equalize any obscurations effects thereof.

34. The sensor head of claim 1 in which the housing includes:

first and second spaced end walls,

a mortise extending from the first end wall to the second wall, and

one of a detent and a depression on at least one of said end walls.

35. The sensor head of claim 34 in which the airway adapter includes:

tubular end portions,

a tenon therebetween received in the mortise of the housing, and

at least one ear including the other of the detent and the depression for releasably locking the airway adapter in the housing.

36. The sensor head of claim 35 in which both the first and second spaced end walls of the housing include a depression on each side of the mortise.

37. The sensor head of claim 36 in which all the depressions are longer than they are wide.

38. The sensor head of claim 37 in which there are two opposing ears, one on each side of the tenon, each ear including a detent longer then it is wide.

39. The sensor head of claim 35 in which the tenon includes spaced opposing side walls.

40. The sensor head of claim 39 in which there is an ear extending outwardly from a proximal end of each side wall.

41. The sensor head of claim 39 further including a ledge extending outwardly from the top of each side wall.

42. The sensor head of claim 39 in which there is an end wall extending outwardly from the distal end of each side wall.

43. The sensor head of claim 42 in which each said end wall also includes the other of the detent and the depression.

44. The sensor head of claim 40 in which there are end walls each extending outwardly from the proximal end of each side wall, each said end wall spaced behind an ear.

45. The sensor head of claim 39 in which each side wall has an orifice therein.

46. The sensor head of claim 45 in which each orifice includes a circumferential seat.

47. The sensor head of claim 46 further including a window in each seat covering the orifice.

48. The sensor head of claim 47 in which the window is treated with an anti-fogging compound.

49. The sensor head of claim 45 in which the mortise includes spaced side walls each including an orifice aligned with the orifices in the side walls of the tenon.

50. The sensor head of claim 49 in which the junction between the side walls of the mortise of the housing and the end walls of the housing are chamfered.

51. The sensor head of claim 1 in which the airway adapter is made of a rigid plastic material.

52. The sensor head of claim 51 in which said rigid plastic material is polystyrene.

53. The sensor head of claim 1 in which the housing is made of metal.

54. The sensor head of claim 53 in which said metal is aluminum.

55. A capnograph system sensor head comprising:

a housing for receiving an airway adapter;

a source of infrared radiation coupled to the housing for directing infrared radiation through the airway adapter;

a detector subsystem coupled to the housing and responsive to the infrared radiation after it passes through the airway adapter for providing an analog output; and

a circuit sub-assembly integrated with the sensor head, the circuit sub-assembly including a controller responsive to the analog output of the detector subsystem, the controller configured to adjust the gain of the detector subsystem and configured to output a digital signal representative of the amount of a particular gas flowing through the airway adapter.

56. A capnograph system sensor head comprising:

an airway adapter;

a housing for receiving the airway adapter;

a source of radiation coupled to the housing for directing radiation through the airway adapter;

a detector subsystem coupled to the housing and responsive to the radiation after it passes through the airway adapter for providing an analog output; and

a circuit sub-assembly integrated with the sensor head, the circuit sub-assembly including means responsive to the analog output of the detector subsystem, for adjusting the gain of the detector subsystem and outputting a digital signal representative of the amount of a particular gas flowing through the airway adapter.

57. The sensor head of claim 56 in which the integrated circuit sub-assembly is disposed on a flex circuit folded and received by the housing.

58. The sensor head of claim 56 further including a cable connected on one end to the housing for transmitting the digital signal.

60. The sensor head of claim 56 in which the circuit subassembly further includes a memory having calibration coefficients for the source and the detector subsystem stored therein.

61. The sensor head of claim 60 in which the memory is a EE PROM.

59. The sensor head of claim 59 in which the circuit subassembly further includes a communications chip connected between the controller and the cable.

62. A capnograph system sensor head comprising:

an airway adapter;

a housing for receiving the airway adapter;

a source of radiation coupled to the housing for directing radiation through the airway adapter;

a detector subsystem coupled to the housing and responsive to the radiation after it passes through the airway adapter for providing an analog output, the detector subsystem including;

a sample sensor,

a reference sensor, and

an integrating lens positioned to integrate the collimated radiation passing through the airway adapter evenly over the sample sensor and the reference sensor so that the instantaneous field of view of the sample sensor and the reference sensor are the same to minimize any obscuration effects thereof; and

a circuit sub-assembly integrated with the housing, the circuit sub-assembly including a controller for processing the analog output.

63. A capnograph system sensor head comprising:

an airway adapter;

a housing for receiving the airway adapter;

a source of radiation coupled to the housing for directing radiation through the airway adapter, the source including;

a radiation source, and

a collimating lens which forms a collimated beam of radiation, the collimating lens is positioned at a distance from the radiation source such that the radiation source is completely imaged by the collimating lens;

a detector subsystem coupled to the housing and responsive to the collimated beam after it passes through the airway adapter for providing an analog output; and

a circuit sub-assembly integrated with the sensor head, the circuit sub-assembly including a controller for processing the analog output.

64. A capnograph system sensor head comprising:

an airway adapter;

a housing for receiving the airway adapter;

a source of radiation coupled to the housing for directing radiation through the airway adapter, the source including;

a header, a filament supported above the header, a TO can mated with the header and including an aperture therein, and a collimating lens positioned in the can between the filament and the aperture which outputs a collimated beam of radiation across the airway adapter;

a detector subsystem coupled to the housing and responsive to the collimated beam after it passes through the airway adapter for providing an analog output, the detector subsystem including a header having a reference sensor and a sample sensor mounted thereon adjacent each other, a filter pack above the reference sensor and sample sensors, a TO can mounted with the header and including an aperture therein, and an integrating lens positioned in the TO can between the aperture therein and the filter pack to integrate the collimated radiation passing through the airway adapter evenly over the sample sensor and the reference sensor so that the instantaneous fields of view of the sample sensor and the reference sensor are the same to minimize any obscuration effects thereof; and

a circuit sub-assembly integrated with the sensor head, the circuit sub-assembly including a controller responsive to the analog output of the detector subsystem, the controller configured to adjust the gain of the detector subsystem and configured to output a digital signal representative of the amount of a particular gas flowing through the airway adapter.

65. A capnograph system sensor head comprising:

an airway adapter;

a housing for receiving the airway adapter, the housing including;

first and second spaced end walls, a mortise extending from the first end wall to the second wall, and one of a detent and a depression on at least one of said end walls;

a source of radiation coupled to the housing for directing radiation through the airway adapter;

a detector subsystem coupled to the housing and responsive to the radiation after it passes through the airway adapter for providing an analog output; and

a circuit sub-assembly integrated with the housing, the circuit sub-assembly including a controller for processing the analog output.

66. A capnograph system sensor head comprising:

an airway adapter;

a housing for receiving the airway adapter, the housing including;

first and second end walls, a mortise extending from the first end wall to the second wall and one of a detent and a depression on at least one of said end walls,

a source of radiation coupled to the housing for directing radiation through the airway adapter, the source including;

a header, a filament supported above the header, a TO can mated with the header and including an aperture therein, and a collimating lens positioned in the can between the filament and the aperture which outputs a collimated beam of radiation across the airway adapter;

a detector subsystem coupled to the housing and responsive to the radiation after it passes through the airway adapter for providing an analog output, the detector subsystem including;

a header having a reference sensor and a sample sensor mounted thereon adjacent each other, a filter pack above the reference sensor and sample sensors, a TO can mounted with the header and including an aperture therein, and an integrating lens positioned in the TO can between the aperture therein and the filter pack to integrate the collimated radiation passing through the airway adapter evenly over the sample sensor and the reference sensor so that the instantaneous fields of view of the sample sensor and the reference sensor are the same to minimize any obscuration effects thereof; and

a circuit sub-assembly integrated with the sensor head, the circuit sub-assembly including a controller responsive to the analog output of the detector subsystem, the controller configured to adjust the gain of the detector subsystem and configured to output a digital signal representative of the amount of a particular gas flowing through the airway adapter.

67. A capnograph system sensor head comprising:

a housing for receiving an airway adapter;

a source of radiation coupled to the housing for directing radiation through the airway adapter;

a detector subsystem coupled to the housing and responsive to the radiation after it passes through the airway adapter for providing an analog output;

an integrated circuit sub-assembly disposed on a flex circuit folded and received by the housing, the circuit sub-assembly including a controller responsive to the analog output of the detector subsystem, the controller configured to adjust the gain of the detector subsystem and configured to output a digital signal representative of the amount of a particular gas flowing through the airway adapter; and

a cable connected on one end to the integrated circuit sub-assembly for transmitting the digital signal, the circuit subassembly further including a communications chip connected between the controller and the cable.