Gas supply device for sleep apnea
First Claim
1. A method for providing air to an airway of a patient, comprising:
- supplying an inspiratory flow of air at a first pressure during a respiratory cycle of a patient;
determining whether the respiratory cycle is a valid respiratory cycle, including,(a) measuring a rate of the inspiratory flow of air,(b) measuring a volume of the inspiratory flow of air,(c) measuring a duration of the inspiratory flow of air,(d) measuring a duration of the respiratory cycle,wherein the respiratory cycle is determined as valid when the rate of the inspiratory flow of air is greater than an inspiratory flow rate threshold, the volume of the inspiratory flow of air is greater than an inspiratory volume threshold, the duration of the inspiratory flow is within an inspiratory duration interval and the duration of the respiratory cycle is within a respiratory cycle duration interval;
incrementing a respiratory cycle counter when the respiratory cycle is determined as valid;
setting a problem appearance indicator, including,(e) determining a sinusoidal curve equivalent to a curve of the inspiratory flow of air during the respiratory cycle,(f) calculating a correlation criterion between the inspiratory flow rate curve and the equivalent sinusoidal curve,(g) calculating a surface criterion proportional to the ratio of an area delimited by the inspiratory flow rate curve to an area delimited by the equivalent sinusoidal curve,(h) setting the problem appearance indicator to a problem absence state or setting the problem appearance indicator to a problem appearance state when the calculated correlation criterion is less than a correlation criterion threshold or when the calculated surface criterion is less than a surface criterion threshold;
incrementing a problem appearance counter when the problem appearance indicator changes from the problem absence state to the problem appearance state; and
increasing the pressure of the inspiratory flow of air above the first pressure when the respiratory cycle has been determined to be a valid respiratory cycle, when the respiratory cycle counter is greater than a respiratory cycle threshold and when the problem appearance counter is greater than or equal to a problem appearance threshold.
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Accused Products
Abstract
An apparatus is provided for controlling air supplied under pressure to a patient suffering from sleep disorders such as apnoea. The apparatus measures and/or calculates the inspiratory air flow, volume and pressure to the airway. Controlled pressurized air is supplied to the patient'"'"'s upper anatomical airway, wherein the apparatus measures the air flow and pressure to the airway. The apparatus determines whether to increase or decrease the pressure to the patient'"'"'s airway based on a determination of one or more factors, such as the occurrence of hypopnoea, hyperventilation, obstructive or central apnoea, air leakage and acoustical vibrations. Occurrences of events representing a sleep problem may be stored by the apparatus and retrieved by a clinician at a later date.
218 Citations
20 Claims
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1. A method for providing air to an airway of a patient, comprising:
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supplying an inspiratory flow of air at a first pressure during a respiratory cycle of a patient; determining whether the respiratory cycle is a valid respiratory cycle, including, (a) measuring a rate of the inspiratory flow of air, (b) measuring a volume of the inspiratory flow of air, (c) measuring a duration of the inspiratory flow of air, (d) measuring a duration of the respiratory cycle, wherein the respiratory cycle is determined as valid when the rate of the inspiratory flow of air is greater than an inspiratory flow rate threshold, the volume of the inspiratory flow of air is greater than an inspiratory volume threshold, the duration of the inspiratory flow is within an inspiratory duration interval and the duration of the respiratory cycle is within a respiratory cycle duration interval; incrementing a respiratory cycle counter when the respiratory cycle is determined as valid; setting a problem appearance indicator, including, (e) determining a sinusoidal curve equivalent to a curve of the inspiratory flow of air during the respiratory cycle, (f) calculating a correlation criterion between the inspiratory flow rate curve and the equivalent sinusoidal curve, (g) calculating a surface criterion proportional to the ratio of an area delimited by the inspiratory flow rate curve to an area delimited by the equivalent sinusoidal curve, (h) setting the problem appearance indicator to a problem absence state or setting the problem appearance indicator to a problem appearance state when the calculated correlation criterion is less than a correlation criterion threshold or when the calculated surface criterion is less than a surface criterion threshold; incrementing a problem appearance counter when the problem appearance indicator changes from the problem absence state to the problem appearance state; and increasing the pressure of the inspiratory flow of air above the first pressure when the respiratory cycle has been determined to be a valid respiratory cycle, when the respiratory cycle counter is greater than a respiratory cycle threshold and when the problem appearance counter is greater than or equal to a problem appearance threshold. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for providing air to an airway of a patient, comprising:
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supplying an inspiratory flow of air at a first pressure during a respiratory cycle of a patient; detecting the presence of an apnoea during the respiratory cycle; measuring a first amplitude of the inspiratory flow of air; measuring a second amplitude of the inspiratory flow of air; identifying the occurrence of a central apnoea when the first amplitude is greater than a first central apnoea threshold and when the second amplitude is less than the first central apnoea threshold; determining a sum of the occurrence of central apnoeas during a time period; and increasing the pressure of the inspiratory flow of air above the first pressure when the presence of an apnoea is detected and the sum of the occurrence of central apnoeas is not greater than a second central apnoea threshold. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for providing air to an airway of a patient, comprising:
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supplying an inspiratory flow of air at a pressure during a respiratory cycle of a patient; determining a flow rate of the inspiratory flow of air during a current respiratory cycle; determining an amplitude of the flow rate; determining a mean amplitude of a flow rate of the inspiratory flow of air during a predetermined number of respiratory cycles; incrementing a hypopnoea time counter when the amplitude of the flow rate during a current respiratory cycle is less than the mean amplitude of the flow rate multiplied by a hypopnoea factor; increasing the pressure of the inspiratory flow of air by a first pressure increase value when the hypopnoea time counter is greater than or equal to a first hypopnoea time threshold; after increasing the pressure of the inspiratory flow of air, reducing the pressure of the inspiratory flow of air by a first pressure reduction value when the pressure of the inspiratory flow of air is less than a comparative pressure value; and after increasing the pressure of the inspiratory flow of air, reducing the pressure of the inspiratory flow of air by a second pressure reduction value when the pressure inspiratory flow of air is greater than or equal to the comparative pressure value. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification