ADMINISTRATION OF CPAP TREATMENT IN PRESENCE OF APNEA

• US 20090038617A1
• Filed: 10/13/2008
• Published: 02/12/2009
• Est. Priority Date: 11/07/1997
• Status: Active Grant

• Current Assignee: ResMed Pty Ltd. (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: BERTHON-JONES, Michael, Farrugia, Steven Paul
• Granted Patent: US 8,220,457 B2
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• 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 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• 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 16/0875 Connecting tubes
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase

Abstract

CPAP treatment apparatus is disclosed having a controllable flow generator (34, 38, 40) operable to produce breathable gas at a treatment pressure elevated above atmosphere to a patient by a delivery tube (32) coupled to a mask (30) having connection with a patient'"'"'s airway. A sensor (44, 50, 56, 58) generates a signal representative of patient respiratory flow, that is provided to a controller (54, 62, 64). The controller (54, 62, 64) is operable to determine the occurrence of an apnea from a reduction in respiratory airflow below a threshold, and if an apnea has occurred, to determine the duration of the apnea and to cause the flow generator (34, 38) to increase the treatment pressure. In one preferred form the increase in pressure is zero if the treatment pressure before the apnea exceeds a pressure threshold. Below the pressure threshold the increase in pressure is an increasing function of the duration of the apnea multiplied by the difference between the pressure threshold and the current treatment pressure.

Claims

1-45. -45. (canceled)

46. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient, comprising the steps of:

determining the occurrence of a respiratory event in the patient'"'"'s upper airway;

if the respiratory event is an apnea and the treatment pressure is below a first predetermined value, then responding to the presence of the apnea by increasing the treatment pressure in a first manner; and

if the respiratory event is a partial upper airway obstruction and the treatment pressure is below a second predetermined value, then responding to the presence of the partial upper airway obstruction by increasing the treatment pressure in a second manner;

said first predetermined value being less than said second predetermined value.

47. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 46 wherein the presence of an apnea is determined based on a measured respiratory flow rate of air of the patient.

48. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 47 wherein the presence of an apnea is determined by the measured respiratory flow rate of air of the patient being reduced below a threshold value.

49. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 46 wherein the presence of a partial upper airway obstruction is determined by detecting the presence of snoring and/or detecting the presence of inspiratory airflow limitation.

50. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 49 wherein detecting the presence of inspiratory airflow limitation is determined by monitoring changes in shape of the inspiratory flow versus time curve of the patient.

51. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 46 wherein said first predetermined value is about 10 cmH2O.

52. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 46 wherein said second predetermined value is about 20 cmH2O.

53. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 46 wherein said first predetermined value is a pressure above which apneas are more likely to be central apneas than obstructive apneas.

54. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 46 wherein if no respiratory event is detected, the treatment pressure is gradually reduced towards a minimum pressure with a predetermined time constant.

55. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 54 wherein the predetermined time constant is between approximately ten minutes and approximately twenty minutes.

56. A method of automatically adjusting a continuous positive airway treatment pressure delivered to a patient in accordance with claim 46 further comprising the step of determining airway patency by using a forced oscillation method.

57. A method of automatically adjusting a CPAP treatment pressure to avoid stimulating the Hering-Breuer reflex comprising the steps of:

providing a supply of air or breathable gas at an automatically adjustable positive treatment pressure to an entrance of the airway of a patient in a range from a minimum pressure to a maximum pressure;

detecting the presence of patient apnea and flow-limitation using a flow-based algorithm;

increasing the treatment pressure in response to flow limitation that occurs when the treatment pressure is in the range from the minimum pressure to the maximum pressure;

increasing the treatment pressure in response to the detection of a patient apnea that occurs when the treatment pressure is below a threshold pressure, said threshold pressure being a pressure that leads to stimulation of the Hering-Breuer reflex and being a pressure less than the maximum pressure; and

leaving the treatment pressure unchanged in response to a patient apnea that occurs at a treatment pressure above said threshold pressure.

58. A method of automatically adjusting a CPAP treatment pressure to avoid stimulating the Hering-Breuer reflex in accordance with claim 57 wherein, the presence of patient apnea is detected only when the treatment pressure is below the threshold pressure.

59. A method of automatically adjusting a CPAP treatment pressure to avoid stimulating the Hering-Breuer reflex in accordance with claim 57 wherein said threshold pressure is about 10 cmH2O.

60. A method of automatically adjusting a CPAP treatment pressure to avoid stimulating the Hering-Breuer reflex in accordance with claim 57 wherein said maximum pressure is about 20 cmH2O.

61. A method of automatically adjusting a CPAP treatment pressure to avoid stimulating the Hering-Breuer reflex in accordance with claim 57 further including the step of determining a conductance of the patient'"'"'s airway and increasing the pressure only when the conductance is below a conductance threshold.

62. A method of automatically adjusting a CPAP treatment pressure to avoid stimulating the Hering-Breuer reflex in accordance with claim 61 wherein the conductance is determined by using a forced oscillation procedure at 4 Hz.

63. An automatically adjusting CPAP apparatus comprising:

a source of air or breathable gas arranged to provide an adjustable positive treatment pressure to an entrance of the airway of a patient; and

a controller that adjusts said positive treatment pressure

(a) in a first manner when the treatment pressure is in a first pressure range to respond to;

(i) indications of the presence of apnea; and

(ii) indications of the presence of inspiratory flow limitation; and

(b) in a second manner when the treatment pressure is in a second, higher pressure range to respond to indications of inspiratory flow limitation.

64. The apparatus of claim 63 wherein in accordance with the first manner the controller increases the treatment pressure to respond to indications of the presence of apnea or indications of the presence of inspiratory flow limitation.

65. The apparatus of claim 63 wherein in accordance with the second manner the controller increases the treatment pressure to respond to indications of inspiratory flow limitation.

66. The apparatus of claim 65 wherein in accordance with the second manner the controller leaves the treatment pressure unchanged in response to apneas.

67. An automatically adjusting CPAP apparatus in accordance with claim 63 wherein said first pressure range is about 4 cmH2O to about 10 cmH2O.

68. An automatically adjusting CPAP apparatus in accordance with claim 63 wherein said second pressure range is about 10 cmH2O to about 20 cmH2O.

69. An automatically adjusting CPAP apparatus in accordance with claim 63 wherein said first pressure range is a pressure range in which an obstructive apnea is more likely to occur than a central apnea.

70. An automatically adjusting CPAP apparatus in accordance with claim 63 wherein said second pressure range is a pressure range in which an open airway apnea is more likely to occur than a closed airway apnea.

71. An automatically adjusting CPAP apparatus in accordance with claim 63 wherein in the first manner and the second manner the controller also adjusts said positive treatment pressure in response to indications of the presence of snoring.

72. An automatically adjusting CPAP apparatus in accordance with claim 63 wherein said controller determines a conductance of the airway using a forced oscillation method and classifies an apnea as either an open airway apnea or a closed airway apnea using said conductance.

73. An automatically adjusting CPAP apparatus that is responsive to the presence of an apnea in accordance with a function of treatment pressure, the apparatus comprising a source of air or breathable gas arranged to provide an adjustable positive treatment pressure to an entrance of the airway of a patient;

and a controller that adjusts said positive treatment pressure according to a first procedure defined by the function when the treatment pressure is such that an obstructive apnea is more likely than a central apnea, and adjusts said positive treatment pressure according to a second procedure defined by the function when the treatment pressure is such that a central apnea is more likely than an obstructive apnea.

74. The automatically adjusting CPAP apparatus of claim 73 wherein said function gives rise to an increase in treatment pressure when an obstructive apnea is more likely than a central apnea.

75. The automatically adjusting CPAP apparatus of claim 73 wherein said function gives rise to substantially no increase in treatment pressure when a central apnea is more likely than an obstructive apnea.

76. The automatically adjusting CPAP apparatus of claim 73 wherein said controller determines that a central apnea is more likely than an obstructive apnea when the treatment pressure is above a threshold value.

77. The automatically adjusting CPAP apparatus of claim 73 wherein said threshold value is about 10 cmH2O.

78. The automatically adjusting CPAP apparatus of claim 73 wherein said controller determines a conductance of the airway using a forced oscillation method and classifies an apnea as an open airway apnea or a closed airway apnea using said conductance.

79. A continuous positive airway pressure device for treating partial or complete upper airway obstruction comprising:

a mask sealingly engaged with a patient'"'"'s face, and including an exhaust port;

a motor driven blower providing a supply of air at positive pressure to an air delivery hose;

said air delivery hose receiving the supply of air from said blower and delivering it to said mask;

a pressure sensor for sensing the pressure at an entrance of the patient'"'"'s airway;

a flow sensor for sensing the flow rate of air through said mask; and

a controller programmed (a) to detect the presence of inspiratory flow limitation in the patient by analyzing said flow rate, (b) to detect the presence of an apnea in the patient, (c) upon detection of an apnea, if the entrance pressure is less than a first pressure threshold, to operate in a first mode to cause an increase in the entrance pressure, and (d) upon detection of the presence of inspiratory flow limitation, if the entrance pressure is less than a second pressure threshold, to operate in a second mode to cause an increase in the entrance pressure;

wherein said first pressure threshold is less than said second pressure threshold.

80. A continuous positive airway pressure device for treating partial or complete upper airway obstruction in accordance with claim 79 wherein said controller is programmed to detect the presence of inspiratory flow limitation by analyzing changes in the shape of the inspiratory flow-versus-time curve.

81. A continuous positive airway pressure device for treating partial or complete upper airway obstruction in accordance with claim 79 wherein said first pressure threshold is about 10 cmH2O.

82. A continuous positive airway pressure device for treating partial or complete upper airway obstruction in accordance with claim 79 wherein said second pressure threshold is about 20 cmH2O.

83. A continuous positive airway pressure device for treating partial or complete upper airway obstruction in accordance with claim 79 wherein said controller determines a conductance of the airway using a forced oscillation method and classifies an apnea as either an open airway apnea or a closed airway apnea using said conductance.

84. A CPAP apparatus comprising:

a source of air or breathable gas to provide a positive treatment pressure to an entrance of the airway of a patient;

at least one sensor that facilitates detection of an apnea; and

a controller that in response to an apnea detection adjusts the positive treatment pressure more aggressively when the existing CPAP pressure is low and it is likely that an apnea is of the closed airway variety, and adjusts the positive treatment pressure less aggressively when the existing CPAP pressure is high and it is likely that an apnea is of the open airway variety.

85. An automatically adjusting CPAP apparatus comprising:

a source of air or breathable gas to provide a positive treatment pressure to an entrance of the airway of a patient; and

a controller that detects an apnea and in response thereto increases the positive treatment pressure in a first manner provided the pressure does not exceed a predetermined apnea pressure limit, and detects a partial upper airway obstruction and in response thereto increases the positive treatment pressure in a second manner provided the pressure does not exceed a maximum pressure limit;

wherein said apnea pressure limit is less than said maximum pressure limit.

86. An automatically adjusting CPAP apparatus in accordance with claim 85 wherein said apnea pressure limit is about 10 cmH2O.

87. An automatically adjusting CPAP apparatus in accordance with claim 85 wherein said maximum pressure limit is about 20 cmH2O.

88. An automatically adjusting CPAP apparatus in accordance with claim 85 wherein said controller determines a conductance of the airway using a forced oscillation method and classifies an apnea as either an open airway apnea or a closed airway apnea using said conductance.

89. A Continuous Positive Airway Pressure device that detects flow limitations and apneas of a patient under treatment during sleep and in response thereto auto-adjusts the treatment pressure comprising:

a breathing tube connectable to a mask for delivery of a supply of air or breathable gas at a treatment pressure to an entrance of the patient'"'"'s airway;

a motor driven blower adapted to provide the supply of air or breathable gas to the breathing tube at a controllable pressure;

a flow sensor arranged to determine a flow of air to the patient;

a controller adapted to detect flow limitations and apneas from said flow signal, and being further adapted to control the treatment pressure in accordance with an auto-adjusting algorithm;

the auto-adjusting algorithm being characterised in that;

the treatment pressure has a range defined by a minimum pressure and a maximum pressure; and

in response to flow limitations, the treatment pressure is increased to a pressure no higher than the maximum pressure; and

in response to apneas, the treatment pressure is increased to a pressure no higher than an apnea cap pressure, wherein the apnea cap pressure is a pressure that is less than the maximum pressure.

90. The device of claim 89 wherein the minimum pressure is about 4 cmH2O.

91. The device of claim 89 wherein the apnea cap pressure is about 10 cmH2O.

92. The device of claim 89 wherein the maximum pressure is about 20 cmH2O.

93. The device of claim 89 used for treatment of Obstructive Sleep Apnea or Upper Airway Resistance syndrome.

94. The device of claim 89 wherein the auto-adjusting algorithm is further characterised in that the treatment pressure is reduced towards the minimum pressure if apnea is not detected.

95. The device of claim 89 wherein the auto-adjusting algorithm is further characterised in that the treatment pressure is reduced towards the minimum pressure if flow limitation is not detected.

96. The device of claim 89 wherein the auto-adjusting algorithm is further characterised in that the treatment pressure is reduced towards the minimum pressure if apnea and flow limitation are not detected.

97. The device of claim 89 wherein the auto-adjusting algorithm is further characterised in that an increment in pressure in response to an apnea when the treatment pressure is close to the apnea cap pressure is smaller than an increment in pressure in response to an apnea when the treatment pressure is close to the minimum pressure.

98. The device of claim 89 wherein the auto-adjusting algorithm includes a leak compensation procedure.

99. The device of claim 98 wherein the leak compensation procedure comprises adjusting the flow limitation threshold if there is a large leak.

100. The device of claims 89 further adapted to distinguish open airway apneas and closed airway apneas using forced oscillation.