DISTINGUISHING BETWEEN CLOSED AND OPEN AIRWAY APNEAS AND TREATING PATIENTS ACCORDINGLY
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Abstract
Methods and apparatus for determining the occurrence of an apnea, patency and/or partial obstruction of the airway are disclosed. Respiratory air flow from a patient is measured to give an air flow signal. The determination of an apnea is performed by calculating the variance of the air flow signal over a moving time window and comparing the variance with a threshold value. One determination of partial obstruction of the airway is performed by detecting the inspiratory part of the air flow signal, scaling it to unity duration and area and calculating an index value of the amplitude of the scaled signal over a mid-portion. Alternatively, the index value is a measure of the flatness of the air flow signal over the mid-portion. One determination of patency of the airway is performed by applying an oscillatory pressure waveform of known frequency to a patient'"'"'s airway, calculating the magnitude of the component of said air flow signal at the known frequency induced by the oscillatory pressure waveform and comparing the calculated magnitude with a threshold value. Alternatively, the air flow signal is analysed to detect the presence of a component due to cardiogenic activity.
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Citations
66 Claims
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1-38. -38. (canceled)
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39. A method for treating an airway disorder of a patient using a CPAP apparatus comprising the steps of:
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delivering an airflow directed toward the patient'"'"'s airway, determining whether air is flowing in the patient'"'"'s airway by generating a signal representing patient breathing; if air is flowing in the patient'"'"'s airway, determining whether the patient'"'"'s airway has a flow restriction; if air is not flowing in the patient'"'"'s airway, determining whether conditions point to the presence of an obstructive apnea or a central apnea; increasing the pressure of the delivered airflow in the same manner if (1) there is an airway flow restriction or (2) conditions are indicative of the presence of an obstructive apnea; and not increasing the pressure of the delivered airflow if (1) air is flowing in the patient'"'"'s airway and the airway is not determined to be flow restricted or (2) conditions point to the presence of a central apnea wherein a flow restriction or a type of apnea is detected based upon a function of said signal representing patient breathing. - View Dependent Claims (40, 41, 42, 43, 44, 45)
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46. An apparatus for treating an airway disorder of a patient comprising:
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a flow sensor for determining whether air is flowing in the patient'"'"'s airway; a processor coupled to said flow sensor; and means for delivering airflow directed toward the patient'"'"'s airway; wherein said processor is programmed (1) to determine if air is flowing in the patient'"'"'s airway by generating a signal representing patient breathing and (2) if air is flowing in the patient'"'"'s airway, to determine whether the patient'"'"'s airway has a flow restriction; (3) if air is not flowing in the patient'"'"'s airway, to determine whether conditions point to the presence of an obstructive apnea or a central apnea; (4) to increase the pressure of the delivered airflow in the same manner if (a) there is an airway flow restriction or (b) conditions are indicative of the presence of an obstructive apnea; and (5) to not increase the pressure of the delivered airflow if (a) air is flowing in the patient'"'"'s airway and the airway is not determined to be flow restricted or (b) conditions point to the presence of a central apnea wherein a flow restriction or a type of apnea is detected based upon a function of said signal representing patient breathing. - View Dependent Claims (47, 48, 49, 50, 51, 52)
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53. Using a CPAP device, a method for detecting the presence of a flow restriction or a type of apnea in the patient comprising the steps of:
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delivering an airflow directed toward the patient'"'"'s airway, determining whether air is flowing in the patient'"'"'s airway by generating a signal representing patient breathing; if air is flowing in the patient'"'"'s airway, determining whether the patient'"'"'s airway has a flow restriction; and if air is not flowing in the patient'"'"'s airway, determining whether conditions point to the presence of an obstructive apnea or a central apnea; wherein a flow restriction or a type of apnea is detected based upon a function of said signal representing patient breathing. - View Dependent Claims (54, 55, 56, 57, 58, 59)
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60. An apparatus for detecting flow restrictions and types of apneas in a patient comprising:
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means for delivering an airflow directed toward a patient'"'"'s airway; a flow sensor for determining whether air is flowing in the patient'"'"'s airway by generating a signal representing patient breathing; and a processor coupled to said flow sensor and said means for delivering an airflow; wherein said processor is programmed to detect flow restrictions and apneas and their types (1) by determining if air is flowing in the patient'"'"'s airway; (2) if air is flowing in the patient'"'"'s airway, determining whether the patient'"'"'s airway has a flow restriction; and (3) if air is not flowing in the patient'"'"'s airway, determining whether conditions point to the presence of an obstructive apnea or a central apnea; and wherein a flow restriction or a type of apnea is detected based upon a function of said signal representing patient breathing. - View Dependent Claims (61, 62, 63, 64, 65, 66)
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Specification