Respiratory pressure treatment apparatus include automated methodologies for controlling changes to pressure in the presence of sleep disordered breathing events. In an example apparatus, various levels of expiratory pressure relief can provide different pressure reductions for patient comfort during expiration (333-A, 333-B, 333-C). The control parameters for these levels may be automatically modified based on the detection of an open airway. Similarly, in some embodiments, the levels may be automatically adjusted based on a detection of persistent obstruction. In still further embodiments, control parameters associated with a rise time of an early portion of an inspiratory pressure treatment may be automatically adjusted upon detection of flow limitation to permit a change to more aggressive waveforms from more comfortable waveforms for the treatment of sleep disordered breathing events.
