What is EPR?

by john

If you use a ResMed S8 CPAP Machine you may be wondering what the EPR option is. I’ve been having a little trouble with my CPAP Nasal mask being comfortable and I decided to read the user manual to see if there were some airflow settings I could change and I found that there was – EPR!

EPR is a ResMed feature that stands for Expiratory Pressure Relief. It is only available on the ResMed S8 version of their CPAP machine. Here is how ResMed describes it:

EPRâ„¢ (expiratory pressure relief) is an effective alternative to continuous positive airway pressure (CPAP) therapy. It features several options that enable you to reliably and predictably control patient therapy while delivering a higher level of patient comfort.

It seems a little weird to me that it is described as an alternative to CPAP therapy because to me it more seems to augment the existing therapy. There are 4 possible settings for EPR on an S8 machine:

OFF
Setting 1 = mild comfort (1 cm H20)
Setting 2 = medium comfort (2 cm H20)
Setting 3 = maximum comfort (3 cm H20)

When I looked at my machine it was set to setting 1. In the interest of experimenting to see if I could get additional comfort I moved the setting to 2 last night and it did seem to be a little bit better where I didn’t feel like I was sucking against as much pressure, however it wasn’t really a good test because I also bumped up the humidity and I set it too high so I was awakened with water in my breathing tube. I’ll try again tonight.

One of the interesting things about EPR is that it offers some control to turn itself off if certain events happen. For example, changes in a patient’s sleeping position or sleep stage (ie, 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.

There is also a timeout period based on exhalation. 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.

The writing is still on the wall for me as to whether this setting will improve my own comfort (I’ll test setting 3 if setting 2 doesn’t seem to work) and I would encourage you to try this feature out yourself.

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