Detection of patient interface disconnect for controlling continuous positive airway pressure therapy
Methods for detecting a patient disconnecting from a continuous positive airway pressure (CPAP) therapy device are disclosed. A cyclical pressure difference signal is derived based upon measurements from a patient interface pressure sensor and from a source pressure sensor. The pressure difference signal is integrated to generate a resultant integral signal for each respiratory cycle, which is comprised of at least one inspiratory phase and at least one expiratory phase as represented by the corresponding portions of the pressure difference signal. A pressure source of the CPAP therapy device is deactivated in response to a disconnect condition being evaluated from the integral signal. In one embodiment, the disconnect condition is the integral signal exceeding a predefined disconnect threshold. In other, it is a slope value corresponding to a rate of increase of the integral signal exceeding a predefined threshold for a predefined duration.
1. A method for terminating pressure output from a continuous positive airway pressure (CPAP) therapy device in response to a patient disconnect, the method comprising:
deriving a cyclical pressure difference signal based upon measurements from a patient interface pressure sensor in communication with the patient interface and from a source pressure sensor in communication with an output of a pressure source of the CPAP therapy device, crests of the pressure difference signal being representative of patient inspiratory phases and troughs of the pressure difference signal being representative of patient expiratory phases;
integrating the pressure difference signal to generate a resultant integral signal;
generating a slope value corresponding to a rate of increase of the integral signal; and
deactivating the pressure source in response to a disconnect condition being evaluated from the integral signal;
wherein the disconnect condition comprises the slope value exceeding a predefined threshold for a predefined duration.
2. The method of claim 1 , wherein the patient disconnect occurs prior to the disconnect condition being evaluated.
3. The method of claim 1 , further comprising:
resetting the integral signal at a minimum of the pressure difference signal for a given respiratory cycle.
4. An article of manufacture comprising a non-transitory program storage medium readable by a data processor of a CPAP therapy device, the medium tangibly embodying one or more programs of instructions executable by the data processor to perform a method for terminating pressure output from a CPAP therapy device in response to a patient disconnect, the method comprising:
deriving a cyclical pressure difference signal based upon measurements from a patient interface pressure sensor in communication with the patient interface and from a source pressure sensor in communication with an output of a pressure source of the CPAP therapy device, crests of the pressure difference signal being representative of patient inspiratory phases and troughs of the pressure difference signal being representative of patient expiratory phases;
integrating the pressure difference signal to generate a resultant integral signal;
generating a slope value corresponding to a rate of increase of the integral signal; and
deactivating the pressure source in response to a disconnect condition being evaluated from the integral signal;
wherein the disconnect condition comprises the slope value exceeding a predefined threshold for a predefined duration.
5. The article of manufacture of claim 4 , wherein the patient disconnect occurs prior to the disconnect condition being evaluated.
6. The article of manufacture of claim 4 , the method further including:
resetting the integral signal at a minimum of the pressure difference signal for a given respiratory cycle.
7. A method for detecting a patient disconnecting from a CPAP therapy device, the method comprising:
measuring a patient interface pressure and a source pressure;
deriving pressure difference values from the measured patient interface pressure and the measured source pressure;
integrating the pressure difference values to generate integral values thereof;
resetting the accumulating integral values at each minimum of the pressure difference values;
generating a slope value corresponding to a rate of increase of the integral values;
deactivating the pressure source in response to an evaluation of the slope value exceeding a predefined disconnect threshold for a predefined duration.
8. The method of claim 7 , wherein the minima of the pressure difference values correspond to patient expiratory phases and maxima of the pressure difference values correspond to patient inspiratory phases.
9. The method of claim 7 , wherein the patient disconnects from the CPAP therapy device prior to the evaluation of the slope value exceeding the predefined disconnect threshold for the predefined duration.
10. The method of claim 7 , wherein:
the patient interface pressure is measured by a first sensor in communication with the patient interface; and
the source pressure is measured by a second sensor in communication with an output of a pressure source of the CPAP therapy device.
11. The method of claim 7 , further comprising:
generating a patient disconnect indication in response to the evaluation of the slope value exceeding the predefined disconnect threshold for the predefined duration.