Apparatus and methods for ventilatory treatment
A ventilatory treatment system is configured to treat respiratory disorders, such as obstructive sleep apnea, Cheyne-Stokes respiration, and/or the like. The system can identify and respond to different types of flow limitations, such as M-shaped inspiratory flow limitation, reverse-chair inspiratory flow limitation, and/or the like. The system can adjust Expiratory Positive Airway Pressure (EPAP) based on real-time measurements of a patient's airflow, ventilation patterns, and/or the identified flow limitation. The system can compute a measure of typical recent ventilation such that a rate of adjustment of the measure of typical recent ventilation is reduced as a measure of recent uncompensated leak increases. The system can compute a target ventilation from a product of the measure of typical recent ventilation and a target fraction, wherein the target fraction is dependent on the recent pressure support. Other embodiments may be described and/or claimed.
1 . An apparatus for treating a respiratory disorder comprising a controller of a therapy device, the apparatus being configured to:
compute a measure of M-shaped inspiratory flow limitation,
compute a proportion of maximum increase in expiratory positive airway pressure (EPAP) as a function of the measure of the M-shaped inspiratory flow limitation,
adjust the proportion of maximum increase in EPAP dependent on a ratio of breathwise ventilation to typical recent ventilation,
increase an EPAP value according to the adjusted proportion of maximum increase in EPAP; and
control, with the controller and the therapy device, delivery of pressure based on the EPAP value.
2 . The apparatus of claim 1 , wherein the apparatus is further configured to decay the EPAP value toward a minimum EPAP value if the computed measure of M-shaped inspiratory flow limitation is zero.
3 . The apparatus of claim 1 , wherein the apparatus is further configured to, if inspiratory duration is greater than a threshold, decay the EPAP value to a minimum EPAP value.
4 . The apparatus of claim 1 , wherein the proportion of maximum increase in EPAP generally decreases as the ratio increases.
5 . The apparatus of claim 1 , wherein the M-shaped inspiratory flow limitation comprises an inspiratory flow waveform having two local peaks, one local peak at a leading edge of the inspiratory flow waveform, and one local peak at a trailing edge of the inspiratory flow waveform, and a relatively flat portion or a dip between the two local peaks.
6 . The apparatus of claim 1 wherein the controller is configured with the therapy device to control delivery of the pressure, wherein the therapy device comprises a motor-driven blower.
7 . A method for treating a respiratory disorder, the method comprising:
computing a measure of M-shaped inspiratory flow limitation,
compute a proportion of maximum increase in expiratory positive airway pressure (EPAP) as a function of the measure of the M-shaped inspiratory flow limitation,
adjust the proportion of maximum increase in EPAP dependent on a ratio of breathwise ventilation to typical recent ventilation,
increasing an EPAP value according to the adjusted proportion of maximum increase in EPAP; and
controlling, with a controller and a therapy device, delivery of pressure based on the EPAP value.
8 . The method of claim 7 , further comprising decaying the EPAP value toward a minimum EPAP value when the computed measure of the M-shaped inspiratory flow limitation is zero.
9 . The method of claim 7 , further comprising decaying the EPAP value to a minimum EPAP value when inspiratory duration is greater than a threshold.
10 . The method of claim 7 , wherein the proportion of maximum increase in EPAP generally decreases as the ratio increases.
11 . The method of claim 7 , wherein the M-shaped inspiratory flow limitation comprises an inspiratory flow waveform having two local peaks, one at a leading edge of the inspiratory flow waveform, and one at a trailing edge of the inspiratory flow waveform, and a relatively flat portion or a dip between the two local peaks.
12 . The method of claim 7 further comprising controlling a motor-driven blower of the therapy device to deliver the pressure.
13 . A non-transitory computer readable storage medium comprising stored processor control instructions configured to control a processor of a respiratory apparatus for treating a respiratory disorder, wherein the stored processor control instructions, when executed by the processor, cause the processor to:
compute a measure of M-shaped inspiratory flow limitation,
compute a proportion of maximum increase in expiratory positive airway pressure (EPAP) as a function of the measure of the M-shaped inspiratory flow limitation,
adjust the proportion of maximum increase in EPAP dependent on a ratio of breathwise ventilation to typical recent ventilation,
increase an EPAP value according to the adjusted proportion of maximum increase in EPAP, and
control delivery of pressure based on the EPAP value.
14 . The computer readable storage medium of claim 13 , wherein the stored processor control instructions are further configured to decay the EPAP value toward a minimum EPAP value if the computed measure of M-shaped inspiratory flow limitation is zero.
15 . The computer readable storage medium of claim 13 , wherein the stored processor control instructions are further configured to decay the EPAP value to a minimum EPAP value if inspiratory duration is greater than a threshold.
16 . The computer readable storage medium of claim 13 , wherein the proportion of maximum increase in EPAP generally decreases as the ratio increases.
17 . The computer readable storage medium of claim 13 , wherein the M-shaped inspiratory flow limitation comprises an inspiratory flow waveform having two local peaks, one at a leading edge of the inspiratory flow waveform, and one at a trailing edge of the inspiratory flow waveform, and a relatively flat portion or a dip between the two local peaks.
18 . The computer readable storage medium of claim 13 wherein the stored processor control instructions are further configured to produce output to control a therapy device comprising a motor-driven blower to deliver the pressure.
19 . An apparatus for treating a respiratory disorder, the apparatus comprising a controller of a therapy device, the apparatus being configured to:
compute a measure of M-shaped inspiratory flow limitation,
compute a plurality of separate pressure components for an increase in expiratory positive airway pressure (EPAP), wherein a pressure component of the computed plurality of separate pressure components is a proportion of a maximum increase in expiratory positive airway pressure (EPAP) that is due to the measure of M-shaped inspiratory flow limitation,
adjust the pressure component that is the proportion of maximum increase in EPAP, dependent on a ratio of breathwise ventilation to typical recent ventilation, and
increase an EPAP value with the pressure component that is the adjusted proportion of maximum increase in EPAP
control, with the controller and the therapy device, delivery of pressure based on the EPAP value.