Methods and apparatus for supplying clean breathable gas

• US 20040112381A1
• Filed: 01/22/2004
• Published: 06/17/2004
• Est. Priority Date: 02/16/2001
• Status: Active Grant

• Current Assignee: ResMed Pty Ltd. (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Drew, Joanne Elizabeth, Berthon-Jones, Michael, Ujhazy, Anthony John, Wright, Jonathan Caldwell
• Granted Patent: US 8,622,057 B2
• Time in Patent Office: Days
• US Class Current: 128/204.18
• CPC Class Codes: A61M 15/00 Inhalators drug delivery in endotracheal tubes A61M16/04
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/0611 with a gusset portion
• CPC Class Codes: A61M 16/0633 with forehead support
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 16/14 by mixing different fluids, one of them being in a liquid phase
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 2205/707 Testing of filters for clogging

Abstract

The invention features methods and apparatus for the treatment of asthma patients. A controlled supply of breathable air delivered to a patient interface or mask (4) is controlled for patient comfort to maintain a steady pressure level in a range 2 to 4 cm H2O to accommodate patient respiration. The breathable air is cleaned by a high efficiency particulate arresting filter (10) to remove allergens from the air supply. The apparatus may be programmed to automatically detect asthma-related symptoms such as an asthma attack by analyzing the respiratory flow of the patient. In response to the detection of such an attack, the apparatus may provide an audible warning or if configured with a treatment delivery module (14A, 14B), the device may administer a therapeutically effective dose of a drug or substance, for example, a broncho-dilator, to alleviate the patient'"'"'s breathing difficulty. Preferred mask designs allow for proper CO2 washout to accommodate the low pressures supplied to the mask and prevent asphyxia.

Claims

1. An apparatus for the delivery of treatment for a patient with asthma, particularly during sleep, comprising:

a blower to generate a flow of breathable gas under pressure, with an inlet for receiving breathable gas to said blower,

a patient interface to provide said flow of breathable gas to the respiratory system of a patient,

a conduit between said interface and said blower to lead said flow of breathable gas to said interface,

a flow meter to generate a flow signal representative of flow to the patient,

a controller to control said blower'"'"'s generation of said flow of breathable gas based in part on said flow signal, and

a cleaning device to clean said breathable gas to substantially prevent allergen particulates from reaching the patient.

2. The apparatus of claim 1 wherein said cleaning device is a filter.

3. The apparatus of claim 2 wherein said filter is a high efficiency particulate arresting filter.

4. The apparatus of claim 3 wherein said filter includes activated carbon.

5. The apparatus of claim 2 wherein said patient interface is a porous mask to insure CO₂ washout at low pressures that covers the patient'"'"'s nose openings and has a sealing membrane thickness in the range of 0.1 mm to 0.3 mm.

6. The apparatus of claim 5 wherein said controller controls said blower so as to vary said flow of breathable gas in response to the patient'"'"'s respiration to maintain a relatively constant pressure at the patent interface.

7. The apparatus of claim 5 wherein said filter is replaceable and wherein said controller is adapted to monitor said blower to assess the filter'"'"'s condition and to generate a warning when the assessment indicates that said filter should be changed.

8. The apparatus of claim 7 wherein said controller detects the number of hours of use of said blower.

9. The apparatus of claim 7 wherein said controller detects the impedance of said filter to assess the filters condition as a function of signals from said flow meter.

10. The apparatus of claim 9 wherein said impedance is determined by the controller from the power of said blower in relation to pressure and flow from the blower.

11. The apparatus of claim 10 where said warning is an alarm.

12. The apparatus of claim 7 wherein said controller is configured to control said blower to generate a range of pressure from 1.75 to 2.5 cm H₂O at the mask.

13. The apparatus of claim 2 wherein said controller includes a processor programmed with instructions for controlling an analysis of data from said flow signal to detect a symptom of asthma.

14. The apparatus of claim 13 wherein said analysis of data is a determination of a flow pattern including the steps of:

calculating a shape index from said data; and

comparing said index to a predetermined threshold.

15. The apparatus of claim 14 wherein said shape index is an indicator of the flatness of an inspiratory portion of patient flow.

16. The apparatus of claim 14 wherein said shape index is an indicator of the roundness of an inspiratory portion of patient flow.

17. The apparatus of claim 14 wherein said shape index is an indicator from an expiratory portion of patient flow.

18. The apparatus of claim 1 further comprising a controlled means for delivering a therapeutic substance to supplement said flow of breathable gas to the patient.

19. The apparatus of claim 18 wherein said controller controls said means for delivering the therapeutic substance to limit delivery of the substance during the patient'"'"'s inspiratory cycle.

20. The apparatus of claim 19 wherein said therapeutic substance is a bronchodilator.

21. The apparatus of claim 20 wherein said controlled means for delivering a therapeutic substance administers said therapeutic substance at said patient interface.

22. The apparatus of claim 13 further comprising a controlled means for delivering a therapeutic substance to supplement said flow of breathable gas to the patient.

23. The apparatus of claim 22 wherein said controller is further programmed with instructions for controlling a delivery of the therapeutic substance by said controlled means in response to a detection of a symptom of asthma.

24. The apparatus of claim 23 wherein said therapeutic substance is a bronchodilator.

25. The apparatus of claim 23 wherein said therapeutic substance is a gas.

26. The apparatus of claim 25 wherein said gas is oxygen.

27. An apparatus for the delivery of treatment for a patient with asthma, particularly during sleep, comprising:

a blower with an inlet to supply breathable gas to a patient interface,

a transducer to generate a flow signal representative of flow of the patient,

a transducer to generate a pressure signal representative of pressure supported by the blower,

a processor to receive data from said flow signal and said pressure signal with programmed instructions for controlling said blower and to detect an asthma symptom from an analysis of said data, and

a filter to substantially remove allergen particulates from the breathable gas flow.

28. The apparatus of claim 27 wherein said filter is a high efficiency particulate arresting filter.

29. The apparatus of claim 28 wherein said filter includes activated carbon.

30. The apparatus of claim 28 wherein said processor controls said blower so as to vary said flow of breathable gas in response to the patient'"'"'s respiration to maintain a relatively constant pressure at the patient interface.

31. The apparatus of claim 29 wherein said patient interface is a porous mask to insure CO₂ washout at low pressures that covers the patients nose openings and has a sealing membrane thickness in the range of 0.1 mm to 0.3 mm.

32. The apparatus of claim 31 wherein said processor is further programmed with instructions to assess filter status and to generate a warning when said assessment indicates that the filter should be changed.

33. The apparatus of claim 27 further comprising a controlled means for delivering a therapeutic substance to supplement said flow of breathable gas to the patient.

34. The apparatus of claim 33 wherein said processor is further programmed with instructions for controlling a delivery of the therapeutic substance by said controlled means in response to a detection of a symptom of asthma.

35. The apparatus of claim 34 wherein said therapeutic substance is a bronchodilator.

36. The apparatus of claim 34 wherein said therapeutic substance is a gas.

37. The apparatus of claim 36 wherein said gas is oxygen.

38. A method for treating a patient with asthma, particularly during sleep, comprising the steps of:

delivering a controlled supply of breathable air to a patient,

providing a patient interface that substantially limits the patient'"'"'s breathable air to the controlled supply of breathable air when it is being supplied through the interface,

cleaning said breathable air in conjunction with the delivery of said breathable air to the patient to substantially remove allergen particulates from said air before said patient inhales said allergen particulates,

monitoring air flow of the patient, and

analyzing said air flow to detect a symptom of asthma.

39. The method of claim 38 wherein said patient interface is a porous mask to insure CO₂ washout at low pressures that is adapted to cover the patient'"'"'s nose openings.

40. The method of claim 38 wherein said patient interface permits a breathable flow of ambient air when said controlled supply of breathable air ceases.

41. The method of claim 39 wherein said controlled supply of breathable air varies in response to the patient'"'"'s respiration to maintain a relatively constant pressure at the patient interface.

42. The method of claim 41 wherein said controlled supply of breathable air is varied in a range of pressure from 1.75 to 2.5 cm H₂O at the mask.

43. The method of claim 42 wherein saidfilter is a high efficiency particulate arresting filter.

44. The method of claim 43 wherein said filter includes activated carbon.

45. The method of claim 41 further comprising the step of administering a therapeutic substance to the patient through the patient interface in response to said detection of a symptom of asthma.

46. The method of claim 44 wherein said therapeutic substance is a broncho-dilator.

47. The method of claim 45 wherein said therapeutic substance is a gas.

48. The method of claim 47 wherein said gas is oxygen.

49. The method of claim 43 further comprising the step of assessing the condition of the filter to determine whether the filter should be changed.

50. The method of claim 49 wherein said step of assessing involves calculating the impedance of the filter.

51. The method of claim 50 wherein said impedance is a function of the blower'"'"'s power consumption.

52. The method of claim 43 wherein said step of analyzing said air flow to detect a symptom of asthma includes the sub-steps of:

calculating a shape index from data representing a portion of said air flow; and

comparing said index to a predetermined threshold.

53. The method of claim 52 wherein said shape index is an indicator of the flatness of an inspiratory portion of patient flow.

54. The method of claim 52 wherein said shape index is an indicator of the roundness of an inspiratory portion of patient flow.

55. The method of claim 52 wherein said shape index is an indicator of the flatness of an expiratory portion of patient flow.

56. The method of claim 52 wherein said shape index is an indicator of the roundness of an expiratory portion of patient flow.

57. An apparatus for the delivery of treatment for a patient with asthma, particularly during sleep, comprising:

a blower to generate a flow of breathable air under pressure, with an inlet for receiving breathable gas to said blower,

a patient interface to provide said flow of breathable air to the respiratory system of a patient,

a conduit between said interface and said blower to lead said flow of breathable air to said interface,

a cleaning device to clean said breathable air to substantially prevent allergen particulates from reaching the patient,

wherein said patient interface includes (1) a shield portion to direct a curtain flow to the patient, (2) a sealing membrane to prevent said flow to the patient'"'"'s upper face and (3) an open cavity to permit a sufficient transfer of ambient air to the patient to prevent asphyxia when said blower ceases generating said flow of breathable air,

58. The apparatus of claim 57 wherein said cleaning device is a filter.

59. The apparatus of claim 58 wherein said filter is a high efficiency particulate arresting filter.

60. The apparatus of claim 59 wherein said flow of breathable air is supplied in an approximate range of pressure from 1.75 to 2.5 cm H₂O.