ADAPTIVE CYCLING FOR RESPIRATORY TREATMENT APPARATUS

• US 20130152934A1
• Filed: 08/25/2011
• Published: 06/20/2013
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: ResMed Pty Ltd. (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Mulqueeny, Qestra Camille, Tassaux, Didier
• Granted Patent: US 9,636,474 B2
• Time in Patent Office: Days
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2230/46 Resistance or compliance of the lungs
• CPC Class Codes: A61M 2230/60 Muscle strain, i.e. measured on the user

Abstract

A controller or processor (s) implements detection of respiratory related conditions that may serve as control logic to synchronize pressure treatment delivery with a patient'"'"'s respiratory cycle. Based on data derived from sensor signals associated with the respiratory treatment, a monitoring device, detector or respiratory treatment apparatus may evaluate flow measures from a flow sensor and distinguish flow attributable to the respiratory treatment apparatus and flow attributable to patient respiratory muscles. The determination may serve as a basis of synchronization criteria that controls pressure levels from a pressure treatment apparatus, such as by evaluating the determined patient generated flow or a relationship between total flow and apparatus flow. In some embodiments, data for the cycling conditions is determined in preliminary treatment cycles during which synchronized pressure changes are controlled according to other cycling criteria. The new cycling conditions are then automatically initiated for control of synchronization in subsequent cycles.

Claims

1. An automated processing method for adapting cycling of a respiratory treatment apparatus that controls a delivery of a synchronized respiratory treatment, the method comprising:

controlling generation of inspiratory pressure and expiratory pressure over a first plurality of cycles with a processor, wherein the setting of the expiratory pressure is based on a first cycling criteria; and

controlling generation of inspiratory pressure and expiratory pressure over a second plurality of cycles subsequent to the first plurality of cycles with the processor, wherein the setting of the expiratory pressure is based on a second cycling criteria, the second cycling criteria being different from the first cycling criteria and being initiated for operation subsequent to the first plurality of cycles.

2. The method of claim 1 wherein the second cycling criteria comprises a function of a first inspiratory flow measure and a second inspiratory flow measure, the second inspiratory flow measure attributable to the respiratory treatment apparatus.

3. The method of claim 2 wherein the first cycling criteria comprises comparing an instantaneous flow measure to a threshold proportion of a peak flow.

4. The method of claim 1 wherein the control of the first plurality of cycles comprises a learning period that is configured for determining and storing values for control of treatment in a plurality of subsequent treatment sessions.

5. The method of claim 1 wherein the control of the first plurality of cycles comprises a learning period that is initiated in each treatment session.

6. The method of claim 1 further comprising determining values of the second cycling criteria during the control of the first plurality of cycles.

7. The method of claim 6 wherein the determined values of the second cycling criteria comprise an inspiratory time constant.

8. The method of claim 7 wherein the inspiratory time constant is a function of a determined slope of an expiratory portion of a measured flow from the first plurality of cycles.

9. The method of claim 8 wherein the inspiratory time constant is a mean of a plurality of determined slopes of expiratory portions of a measured flow from the first plurality of cycles.

10. The method of claim 7 wherein the inspiratory time constant is a measured time for a proportion of a tidal volume to be delivered to the patient'"'"'s respiratory system in a cycle of the first plurality of cycles.

11. The method of claim 10 wherein the inspiratory time constant is a mean of measured times for a proportion of a tidal volume to be delivered to the patient'"'"'s respiratory system in the first plurality of cycles.

12. The method of claim 7 wherein a determination of the inspiratory time constant comprises a multiple linear regression process to fit pressure, flow and volume data for determining a measure of resistance and compliance.

13. The method of claim 2 wherein the function of the first inspiratory flow measure and the second inspiratory flow measure comprises an equality of the first inspiratory flow measure and the second inspiratory flow measure.

14. The method of claim 2 wherein the function of the first inspiratory flow measure and the second inspiratory flow measure comprises a calculated difference of the first inspiratory flow measure and the second inspiratory flow measure.

15. The method of claim 2 wherein the second inspiratory flow measure is a function of a determined flow peak, a calculated respiratory resistance and a pressure treatment setting.

16. A respiratory treatment apparatus for cycling synchronized respiratory pressure treatment, the apparatus comprising:

a patient interface to direct a breathable gas;

a flow generator coupled with the patient interface to generate the breathable gas in inspiratory and expiratory pressure cycles through the patient interface;

a flow sensor to provide a signal indicative of flow through the patient interface;

a processor, coupled with the flow generator and the flow sensor, the processor configured to control;

generation of inspiratory pressure and expiratory pressure over a first plurality of cycles, wherein the setting of the expiratory pressure is based on a first cycling criteria; and

generation of inspiratory pressure and expiratory pressure over a second plurality of cycles subsequent to the first plurality of cycles, wherein the setting of the expiratory pressure is based on a second cycling criteria, the second cycling criteria being different from the first cycling criteria and being initiated for operation subsequent to the first plurality of cycles.

17. The apparatus of claim 16 wherein the second cycling criteria comprises a function of a first inspiratory flow measure from the flow sensor and a second inspiratory flow measure attributable to the respiratory treatment apparatus.

18. The apparatus of claim 17 wherein the first cycling criteria comprises comparing an instantaneous flow measure to a threshold proportion of a peak flow.

19. The apparatus of claim 16 wherein the control of the first plurality of cycles comprises a learning period that is configured for determining and storing values for control of treatment in a plurality of subsequent treatment sessions.

20. The apparatus of claim 16 wherein the control of the first plurality of cycles comprises a learning period that is initiated in each treatment session.

21. The apparatus of claim 16 further comprising determining values of the second cycling criteria during the control of the first plurality of cycles.

22. The apparatus of claim 21 wherein the determined values of the second cycling criteria comprise an inspiratory time constant.

23. The apparatus of claim 22 wherein the inspiratory time constant is a function of a determined slope of an expiratory portion of a measured flow from the first plurality of cycles.

24. The apparatus of claim 23 wherein the inspiratory time constant is a mean of a plurality of determined slopes of expiratory portions of a measured flow from the first plurality of cycles.

25. The apparatus of claim 22 wherein the inspiratory time constant is a measured time for a proportion of a tidal volume to be delivered to the patient'"'"'s respiratory system in a cycle of the first plurality of cycles.

26. The apparatus of claim 25 wherein the inspiratory time constant is a mean of measured times for a proportion of a tidal volume to be delivered to the patient'"'"'s respiratory system in the first plurality of cycles.

27. The apparatus of claim 22 wherein the inspiratory time constant is calculated as a function of resistance and compliance values determined by a multiple linear regression process with pressure, flow and volume data.

28. The apparatus of claim 17 wherein the function of the first inspiratory flow measure and the second inspiratory flow measure comprises an equality of the first inspiratory flow measure and the second inspiratory flow measure.

29. The apparatus of claim 17 wherein the function of the first inspiratory flow measure and the second inspiratory flow measure comprises a calculated difference of the first inspiratory flow measure and the second inspiratory flow measure.

30. The apparatus of claim 17 wherein the second inspiratory flow measure is a function of a determined flow peak, a calculated respiratory resistance and a pressure treatment setting.

31. An automated processing method for cycling a respiratory treatment apparatus that controls a delivery of a synchronized respiratory treatment, the method comprising:

determining a first flow measure with a flow sensor;

determining a second flow measure attributable to the respiratory treatment apparatus; and

evaluating, with a processor, a cycling criteria as a function of the first flow measure and the second flow measure.

32. The automated method of claim 31 wherein the evaluation of the cycling criteria is a further function of a tolerance coefficient.

33. The method of claim 31 wherein the determining of the second flow measure attributable to the respiratory treatment apparatus comprises calculating the second flow measure as function of an inspiratory resistance value and an inspiratory time constant value.

34. The method of claim 33 further comprising calculating the inspiratory resistance value.

35. The method of claim 34 wherein the calculating of the inspiratory resistance value comprises a function of airway pressure and flow.

36. The method of claim 35 wherein the airway pressure comprises a difference of a positive end expiratory pressure and an airway pressure following a peak in a measure of respiratory flow.

37. The method of claim 33 wherein the calculating the second flow measure is a further function of a ventilator time constant.

38. The method of claim 37 wherein the calculating the second flow measure is a further function of a pressure support setting.

39. The method of claim 31 wherein the evaluation of the cycling criteria comprises assessing an equality of the first flow measure and the second flow measure

40. The method of claim 31 wherein the evaluation of the cycling criteria comprises calculating a difference of the first flow measure and the second flow measure.

41. The method of claim 40 wherein the evaluation of the cycling criteria further comprises comparing the difference to a threshold.

42. The method of claim 41 wherein the threshold is zero.

43. The method of claim 31 further comprising setting an expiratory pressure based on the evaluation of the cycling criteria.

44. The method of claim 31 wherein the expiratory pressure comprises a positive end expiratory pressure.

45. The method of claim 31 further comprising:

controlling generation of inspiratory pressure and expiratory pressure over a first number of cycles, wherein the setting of the expiratory pressure is based on a first cycling criteria;

during the first number of cycles, determining an inspiratory time constant as a function of flow measures;

setting a second cycling criteria as a function of the determined inspiratory time constant, the second cycling criteria for controlling generation of expiratory pressure over a second number of cycles subsequent to the first number of cycles.

46. The method of claim 45 wherein the determined inspiratory time constant comprises a slope of an expiratory part of a curve represented by the flow measures.

47. The method of claim 46 wherein the determined inspiratory time constant comprises a mean slope.

48. The method of claim 45 wherein the first cycling criteria comprises a threshold proportion of flow and the second cycling criteria comprises the cycling criteria of the function of the first flow measure and the second flow measure attributable to the respiratory treatment apparatus.

51. The apparatus of claim 31 wherein the determination of the second flow measure attributable to the respiratory treatment apparatus comprises calculating the second flow measure as function of an inspiratory resistance value and an inspiratory time constant value.

52. The apparatus of claim 51 wherein the processor is further configured to calculate the inspiratory resistance value.

53. The apparatus of claim 52 wherein the calculation of the inspiratory resistance value comprises a function of airway pressure and flow.

54. The apparatus of claim 53 wherein the airway pressure comprises a difference of a positive end expiratory pressure and an airway pressure following a peak in a measure of respiratory flow.

55. The apparatus of claim 54 wherein the calculation of the second flow measure is a further function of a ventilator time constant.

56. The method of claim 55 wherein the calculation of the second flow measure is a further function of a pressure support setting.

49. A respiratory treatment apparatus for cycling synchronized respiratory pressure treatment, the apparatus comprising:

a patient interface to direct a breathable gas;

a flow generator coupled with the patient interface to generate the breathable gas in inspiratory and expiratory pressure cycles through the patient interface;

a flow sensor to provide a signal indicative of patient flow through the patient interface;

a processor, coupled with the flow generator and the flow sensor, the processor configured to control;

a determination of a first flow measure from the flow sensor;

a determination of a second flow measure attributable to the respiratory treatment apparatus; and

an evaluation of a cycling criteria as a function of the first flow measure and the second flow measure.

50. The apparatus of claim 49 wherein the evaluation of the cycling criteria is a further function of a tolerance coefficient.

57. The apparatus of claim 49 wherein the evaluation of the cycling criteria comprises an assessment of an equality of the first flow measure and the second flow measure.

58. The apparatus of claim 49 wherein the evaluation of the cycling criteria comprises a calculation of a difference of the first flow measure and the second flow measure.

59. The apparatus of claim 58 wherein the evaluation of the cycling criteria further comprises comparing the difference to a threshold.

60. The apparatus of claim 59 wherein the threshold is zero.

61. The apparatus of claim 49 wherein the processor is configured to set an expiratory pressure based on the evaluation of the cycling criteria.

62. The apparatus of claim 49 wherein the expiratory pressure comprises a positive end expiratory pressure.

63. The apparatus of claim 49 wherein the processor is further configured to:

control generation of inspiratory pressure and expiratory pressure over a first number of cycles, wherein the setting of the expiratory pressure is based on a first cycling criteria;

during the first number of cycles, control a determination of an inspiratory time constant as a function of flow measures;

set a second cycling criteria as a function of the determined inspiratory time constant, the second cycling criteria to control generation of expiratory pressure over a second number of cycles subsequent to the first number of cycles.

64. The apparatus of claim 63 wherein the determined inspiratory time constant comprises a slope of an expiratory part of a curve represented by the flow measures.

65. The apparatus of claim 64 wherein the determined inspiratory time constant comprises a mean slope.

66. The apparatus of claim 63 wherein the first cycling criteria comprises a threshold proportion of flow and the second cycling criteria comprises the cycling criteria of the function of the first flow measure and the second flow measure attributable to the respiratory treatment apparatus.

67. An automated processing method to determine a signal indicative of patient respiration for synchronization of a respiratory treatment apparatus, the method comprising:

determining a first inspiratory flow measure with a flow sensor;

determining a second inspiratory flow measure; and

determining, with a processor, a patient respiration measure as a function of the first inspiratory flow measure, the second inspiratory flow measure and an estimate of resistance and compliance derived from an expiratory portion of a flow measure of the flow sensor, the patient respiratory measure representing patient respiratory muscles effort; and

determining a timing for switching a pressure treatment based on the respiration measure.

68. The method of claim 67 wherein the second inspiratory flow measure is a measure of flow attributable to the respiratory treatment apparatus.

69. The method of claim 68 further comprising calculating a resistance value for the estimate.

70. The method of claim 69 wherein the calculating of the resistance value comprises a function of airway pressure and flow.

71. The method of claim 70 further comprising calculating a compliance value for the estimate.

72. The method of claim 71 wherein the calculating the resistance and compliance values comprises multiple linear regression processing of an expiratory breath data portion, the expiratory breath data portion beginning with expiration and ending before a next inspiration.

73. The method of claim 72 wherein the ending before the next inspiration comprises a percentage of the tidal volume expired.

74. The method of claim 68 further comprising calculating a difference of the first inspiratory flow measure and the second inspiratory flow measure.

75. A monitoring apparatus to determine a signal indicative of patient respiration for synchronization of a respiratory treatment, the apparatus comprising:

a controller having at least one processor to access data representing a measured flow of breathable gas from a flow sensor, the controller being further configured to;

determine a first inspiratory flow measure with the data;

determine a second inspiratory flow measure; and

determine a patient respiration signal as a function of the first inspiratory flow measure, the second inspiratory flow measure and an estimate of resistance and compliance derived from an expiratory portion of a flow measure of the flow sensor, the patient respiratory signal representing effort attributable to patient respiratory muscles; and

determine a timing for switching a pressure treatment based on the respiration measure.

76. The apparatus of claim 75 wherein the controller is further configured to calculate a resistance value for the estimate.

77. The apparatus of claim 76 wherein the calculation of the resistance value comprises a function of airway pressure and flow.

78. The apparatus of claim 77 wherein the controller is further configured to calculate a compliance value for the estimate.

79. The apparatus of claim 77 wherein the calculation of the resistance and compliance values of the estimate is performed by the controller in multiple linear regression processing of an expiratory breath data portion, the expiratory breath data portion beginning with expiration and ending before a next inspiration.

80. The apparatus of claim 75 wherein the ending before the next inspiration comprises a percentage of the tidal volume expired.

81. The apparatus of claim 75 wherein the controller is further configured to calculate a difference of the first inspiratory flow measure and the second inspiratory flow measure.

82. An automated processing method for cycling a respiratory treatment apparatus that controls a delivery of a synchronized respiratory treatment, the method comprising:

determining a flow measure with a flow sensor;

determining a pressure measure with a pressure sensor;

determining, with a processor, an estimate of muscle effort as a function of the flow measure and pressure measure; and

deriving, with the processor, a cycling control signal as a function of the estimate of muscle effort.

83. The method of claim 82 wherein the determining the estimate is a further function of an estimate of respiratory resistance and compliance.

84. The method of claim 83 wherein the estimate of respiratory resistance and compliance is determined as a function of a portion of patient expiration.

85. The method of claim 84 wherein the estimate is derived from pressure, flow and volume measures taken during the portion of patient expiration.

86. The method of claim 85 wherein the derived estimate is produced by multiple linear regression processing of the pressure, flow and volume measures taken during the portion of patient expiration beginning at patient expiration and ending when approximately ninety percent of a tidal volume has been expired.

87. The method of claim 82 further comprising determining a peak value of the control signal.

88. The method of claim 87 further comprising cycling the respiratory treatment apparatus as a function of a proportion of the peak value and the control signal.

89. The method of claim 88 wherein deriving the control signal comprises setting the control signal to equal the estimate of muscle effort if the estimate of muscle effort is increasing.

90. The method of claim 89 wherein deriving the control signal comprises setting the control signal to zero upon detection of inspiration or if the estimate of muscle effort is decreasing.

91. A respiratory treatment apparatus for cycling synchronized respiratory pressure treatment, the apparatus comprising:

a patient interface to direct a breathable gas;

a flow generator coupled with the patient interface to generate the breathable gas in inspiratory and expiratory pressure cycles through the patient interface;

a flow sensor to provide a signal indicative of patient flow through the patient interface;

a pressure sensor to provide a signal indicative of pressure at the patient interface;

a processor, coupled with the flow generator, the pressure sensor and the flow sensor, the processor configured to control;

a determination of a flow measure with the flow sensor;

a determination of a pressure measure with the pressure sensor;

a determination of an estimate of muscle effort as a function of the flow measure and pressure measure; and

a derivation of a cycling control signal as a function of the estimate of muscle effort.

92. The apparatus of claim 91 wherein the determination of the estimate is a further function of an estimate of respiratory resistance and compliance.

93. The apparatus of claim 92 wherein the estimate of respiratory resistance and compliance is determined as a function of a portion of patient expiration.

94. The apparatus of claim 93 wherein the estimate is derived from pressure, flow and volume measures taken during the portion of patient expiration.

95. The apparatus of claim 94 wherein the derived estimate is produced by multiple linear regression processing of the pressure, flow and volume measures taken during the portion of patient expiration beginning at patient expiration and ending when approximately ninety percent of a tidal volume has been expired.

96. The apparatus of claim 91 wherein the processor further controls a determination of a peak value of the control signal.

97. The apparatus of claim 96 wherein the processor further controls cycling the respiratory treatment apparatus as a function of a proportion of the peak value and the control signal.

98. The apparatus of claim 97 wherein the derivation of the control signal comprises setting the control signal to equal the estimate of muscle effort if the estimate of muscle effort is increasing.

99. The apparatus of claim 98 wherein the derivation of the control signal further comprises setting the control signal to zero upon detection of inspiration or if the estimate of muscle effort is decreasing.

100. A respiratory treatment apparatus for switching synchronized respiratory pressure treatment, the apparatus comprising:

a patient interface to direct a breathable gas;

a flow generator coupled with the patient interface to generate the breathable gas in inspiratory and expiratory pressure cycles through the patient interface;

an electro-optical sensor for non-invasively measuring diaphragmatic muscle activity; and

a processor, coupled with the flow generator and the sensor, the processor configured to control;

a determination of muscle effort signal with the sensor; and

a derivation of a switching control signal as a function of the muscle effort signal.

101. The apparatus of claim 100 wherein the processor further controls a determination of a peak value of the control signal.

102. The apparatus of claim 100 wherein the processor further controls cycling the respiratory treatment apparatus as a function of a proportion of the peak value and the control signal.

103. The apparatus of claim 102 wherein the derivation of the control signal comprises setting the control signal to equal the muscle effort signal if the muscle effort signal is increasing.

104. The apparatus of claim 103 wherein the derivation of the control signal further comprises setting the control signal to zero upon detection of inspiration or if the muscle effort signal is decreasing.

105. The apparatus of claim 100 wherein the processor further controls cycling a pressure treatment controlled by the apparatus is a function of the switching control signal.

106. The apparatus of claim 100 wherein the processor further controls triggering a pressure treatment controlled by the apparatus is a function of the switching control signal.