The Event Detection Circuit is a backup feature of the EPR algorithm. Changes in a patient's sleeping position or sleep stage (i.e., REM sleep) may cause sudden, unpredictable events to occur without the typical preceding flow limitation or snoring. When such an event is detected, EPR immediately suspends, and the treatment pressure reverts to set CPAP. EPR remains suspended until the event concludes and normal breathing resumes.

If a patient's exhalation period exceeds 15 seconds, EPR immediately suspends. The treatment pressure reverts to set CPAP and remains suspended until the next inhalation phase is detected. EPR helps patients experience the highest level of comfort and benefit from their therapy. EPR is available on ResMed’s S8 Elite^TM and the S8 AutoSet Vantage^TM flow generators

Respironics‘s C-flex Technology 

How a CPAP with C-Flex Works. C-flex tracks your breathing to lower the amount of pressure delivered at first few seconds of exhalation.  The patient has access to three C-flex setting to control how much pressure is released on exhalation. This allows the patient to choose what they feel is the right level of pressure relief for there comfort.