Distinguishing between closed and open airway apneas and treating patients accordingly
First Claim
1. Continuous positive airway pressure apparatus for treatment of respiratory conditions of a patient comprising:
- means for determining a signal representative of patient respiratory flow;
a motor driven blower; and
a controller for detecting (i) flow limitations, (ii) apneas and (iii) hypopneas by operating on said signal indicative of patient respiratory flow; and
for controlling the motor driven blower to increase automatically a treatment pressure upon detection of any of a flow limitation, apnea and hypopnea, wherein the detection of hypopnea is based on a calculated variance of said respiratory flow, and otherwise to automatically decrease the treatment pressure.
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Accused Products
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.
189 Citations
14 Claims
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1. Continuous positive airway pressure apparatus for treatment of respiratory conditions of a patient comprising:
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means for determining a signal representative of patient respiratory flow; a motor driven blower; and a controller for detecting (i) flow limitations, (ii) apneas and (iii) hypopneas by operating on said signal indicative of patient respiratory flow; and
for controlling the motor driven blower to increase automatically a treatment pressure upon detection of any of a flow limitation, apnea and hypopnea, wherein the detection of hypopnea is based on a calculated variance of said respiratory flow, and otherwise to automatically decrease the treatment pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification