Apparatus and method for controlling the administration of CPAP treatment
First Claim
1. A method for determining an occurrence of an apnea in a patient, the method comprising the steps of:
- measuring respiratory air flow from a patient as a function of time;
determining a variance of said measured air flow; and
determining from said variance that an apnea is occurring.
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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.
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Citations
63 Claims
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1. A method for determining an occurrence of an apnea in a patient, the method comprising the steps of:
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measuring respiratory air flow from a patient as a function of time;
determining a variance of said measured air flow; and
determining from said variance that an apnea is occurring. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for controlling the administration of CPAP treatment to the airway of a patient by means controllable to supply breathable air to the patient'"'"'s airway continually at a selectable pressure elevated above atmospheric pressure, the method comprising the steps of:
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determining a presence or absence of an apnea, and (a) if an apnea is occurring then;
determining whether the airway is patent, and if not patent then increasing the CPAP treatment pressure;
else(b) if an apnea is not occurring then;
determining a presence and a magnitude of partial obstruction, and if there is partial obstruction then increasing the CPAP treatment pressure as a function of the magnitude of the partial obstruction, else if there is no partial obstruction, reducing the CPAP treatment pressure. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
measuring respiratory air flow from the patient;
detecting an inspiratory part of said air flow; and
determining an index value of a mid-portion of said inspiratory part as a measure of partial obstruction.
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11. The method of claim 10, whereby said mid-portion is a middle half of said inspiratory part.
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12. The method of claim 10, whereby said index value is determined from an amplitude of said mid-portion of said inspiratory part.
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13. The method of claim 12, whereby said index value is determined as an arithmetic mean value of said amplitude in said mid-portion.
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14. The method of claim 12, whereby said index value is determined from a flatness of said mid-portion of said inspiratory part.
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15. The method of claim 14, whereby said index value is determined as a root mean square (RMS) deviation of said inspiratory part in said mid-portion with respect to unity.
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16. The method of claim 14, wherein said index value is a ratio of a mean of said mid-portion of said inspiratory part to a mean of said inspiratory part.
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17. The method of claim 8, whereby the magnitude of the pressure increase is a decreasing function of an existing treatment pressure.
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18. The method of claim 8, whereby the magnitude of the pressure increase is a decreasing function of the extent of mask or mouth leak.
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19. The method of claim 8, whereby the pressure increase in response to an apnea is performed at the end of the apnea.
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20. Apparatus for controlling administration of CPAP treatment to the airway of a patient comprising:
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air supply means controllable to supply breathable air to a patient'"'"'s airway continually at a selectable pressure elevated above atmospheric pressure; and
controlling means, coupled to the air supply means, operable to cause a change in the CPAP treatment, pressure by determining the presence or absence of an apnea, and (a) if an apnea is occurring then;
determining whether the airway is patent, and if not patent then causing an increase in the CPAP treatment pressure;
else(b) if an apnea is not occurring then;
determining a presence and a magnitude of partial obstruction, and if there is partial obstruction then causing an increase in the CPAP treatment pressure as a function of the magnitude of the partial obstruction, else if there is no partial obstruction, causing a reduction in the CPAP treatment pressure. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A method for controlling the administration of CPAP treatment to the airway of a patient by controlling the supply of breathable air at a selectable pressure elevated above atmospheric pressure, the method comprising the step of commencing or increasing CPAP treatment pressure to a patient when an apnea is detected only if the patient'"'"'s airway is not patent, wherein said airway is determined to be patent by:
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applying an oscillatory pressure waveform of known frequency to the patient'"'"'s airway;
measuring respiratory air flow from the patient; and
determining if the airway is patent by detecting a component of said air flow at said known frequency induced by said oscillatory pressure waveform. - View Dependent Claims (33, 34, 35)
measuring respiratory air flow of the patient over time; and
determining the variance of said air flow as an indication that an apnea is occurring.
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34. The method of claim 33 further comprising the step of commencing or increasing CPAP treatment pressure if there is partial obstruction of the airway determined by the steps of:
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measuring respiratory air flow from the patient;
detecting the inspiratory part of said air flow; and
determining an index value of a mid-portion of said inspiratory part as a measure of partial obstruction.
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35. The method of claim 34 further comprising the step of reducing CPAP treatment pressure if:
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(a) there is no apnea occurring and there is no partial obstruction;
or(b) there is an apnea occurring but the airway is patent.
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36. A method for controlling the administration of CPAP treatment to the airway of a patient by controlling the supply of breathable air at a selectable pressure elevated above atmospheric pressure, the method comprising the step of commencing or increasing CPAP treatment pressure to a patient when an apnea is detected only if the patient'"'"'s airway is not patent, wherein said airway is determined to be patent by:
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measuring respiratory air flow from the patient; and
determining if the airway is patent by detecting a presence of cardiogenic air flow from said respiratory air flow. - View Dependent Claims (37, 38, 39)
measuring respiratory air flow of the patient over time; and
determining the variance of said air flow as an indication that an apnea is occurring.
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38. The method of claim 37 further comprising the step of commencing or increasing CPAP treatment pressure if there is partial obstruction of the airway determined by the steps of:
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measuring respiratory air flow from the patient;
detecting the inspiratory part of said air flow; and
determining an index value of a mid-portion of said inspiratory part as a measure of partial obstruction.
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39. The method of claim 38 further comprising the step of reducing CPAP treatment pressure if:
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(a) there is no apnea occurring and there is no partial obstruction;
or(b) there is an apnea occurring and the airway is patent.
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40. Apparatus for control of the administration of CPAP treatment to the airways of a patient, the apparatus comprising:
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a mask for the provision of breathable gas to a patient'"'"'s airways;
a conduit connected with said mask;
a controllable flow generator to supply said breathable gas to said conduit at a controlled pressure elevated above atmospheric pressure;
a pressure transducer responsive to the patient'"'"'s respiration to output a signal representative of respiratory airflow; and
a processor to process said airflow signal and to control said flow generator wherein said processor;
calculates a variance of said airflow signal;
increases the controlled pressure if a comparison between said variance with a threshold indicates an apnea is occurring. - View Dependent Claims (41, 42, 43)
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44. A method for detecting partial obstruction of the airway of a patient, the method comprising the steps of:
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measuring patient respiratory airflow over time;
determining air flow values from the measure of respiratory air flow during the course of a breath;
identifying inspiratory values from said air flow values; and
determining a measure of partial obstruction which is a ratio of a mean of a mid-portion of said inspiratory values to a mean of said inspiratory values. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51)
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52. Apparatus for detecting partial obstruction of the airway of a patient comprising:
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sensor means responsive to a patient'"'"'s respiration to output a signal representative of respiratory airflow; and
processor means, coupled to the sensor means, to receive said signal, wherein said processor means;
determines air flow values from said signal during the course of a breath;
identifies inspiratory values from said air flow values; and
determines a measure of partial obstruction which is a ratio of a mean of a mid-portion of said inspiratory values to a mean of said inspiratory values. - View Dependent Claims (53)
air supply means controllable to supply breathable air to the patient'"'"'s airway continually at a selectable pressure elevated above atmospheric pressure, wherein said processor means causes said air supply means to commence or increase continuous positive airway pressure when said measure of partial obstruction is less than a threshold.
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54. An apparatus for detecting partial obstruction of the airway of a patient comprising:
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a pressure transducer responsive to the patient'"'"'s respiration to output a signal representative of respiratory airflow; and
a processor to process said airflow signal and wherein said processor;
determines air flow values from said signal during the course of a breath;
identifies inspiratory values from said air flow values; and
determines a measure of partial obstruction which is a ratio of a mean of a mid-portion of said inspiratory values to a mean of said inspiratory values. - View Dependent Claims (55)
a mask for the provision of breathable gas to a patient'"'"'s airways;
a conduit connected with said mask; and
a controllable flow generator to supply said breathable gas to said conduit at a controlled pressure elevated above atmospheric pressure, wherein said processor causes said air supply means to commence or increase continuous positive airway pressure when said measure of partial obstruction is less than a threshold.
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56. A method for determining a degree of obstruction of the airway of a patient receiving continuous positive airway pressure (CPAP) treatment by apparatus for supplying CPAP to the patient'"'"'s airway, the method comprising the steps of:
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measuring respiratory air flow from a patient to give an air flow signal which may include a snore component;
predicting an expected flow signal; and
subtracting said expected flow signal from said air flow signal to yield a snore component signal as a measure of a degree of obstruction of the airway. - View Dependent Claims (57, 58, 59)
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60. An apparatus for detecting partial obstruction of the airway of a patient comprising:
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a mask for the provision of breathable gas to a patient'"'"'s airways;
a conduit connected with said mask;
a controllable flow generator to supply said breathable gas to said conduit at a controlled pressure elevated above atmospheric pressure;
a pressure transducer in sound communication with the patient'"'"'s respiratory system to generate a flow signal;
a tachometer for said flow generator to give a speed signal; and
a processor to process said flow signal from said transducer and said speed signal from said tachometer and to control said flow generator, wherein said processor;
predicts an expected flow using said flow signal and said speed signal; and
subtracts said expected flow from said flow signal to yield a snore signal as a measure of a degree of obstruction of the airway. - View Dependent Claims (61)
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62. An apparatus for detecting partial obstruction of the airway of a patient comprising:
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air supply means controllable to supply breathable air to a patient'"'"'s airway continually at a selectable pressure elevated above atmospheric pressure;
a flow sensor means to generate a flow signal representative of respiratory airflow and patient snoring;
a speed sensor means for said air supply means; and
a processor means to process a flow signal from said flow sensor and a speed signal from said speed sensor and to control said air supply means, wherein said processor;
predicts an expected flow using said flow signal and said speed signal; and
subtracts said expected flow from said flow signal to yield a snore signal as a measure of a degree of obstruction of the airway. - View Dependent Claims (63)
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Specification