Using ResMed S8 AutoSet II Stats to Track CPAP Effectiveness


If you really want to know how to change/access your settings on a ResMed S8 AutoSet II or an S8 Elite then you can find the instructions on the Change CPAP Pressure Settings page at However, I recommend that you first read my comments on this in my Living with a CPAP (Obstructive Sleep Apnea Treatment) page.

A couple of weeks ago I started tracking how I felt after a night of sleep using a calendar. I’ve since graduated to maintaining an Excel spreadsheet that logs this information using a scale of zero to five (zero = severe fatigue, five = well rested). A couple of days ago I started checking the morning’s effectiveness stats and recording that in the same spreadsheet.

My device provides pressure, leak rate (l/s), AHI, AI, and HI. You can find more information about what these stats mean over at OSA and several other resources.

Since I don’t have access to the ResScan software I can’t view historical details, just averages and the stats for the last time the device was used. For now, I’m entering each night’s stats into an Excel spreadsheet.

I just changed from a ResMed Mirage Quattro Full Face Mask over to a Fisher and Paykel Forma Full Face Mask. I’ve only used it one night but, unless it was a fluke, it already seems to have improved my treatment.

Here are stats from the night before, when I used the Quattro, followed by the first night using the Forma:

Wednesday Night (Quattro)

Leak (L/s): 0.06
AHI: 5.1
AI: 0.3
HI: 4.8

Thursday Night (Forma)

Leak (L/s): 0.44
AHI: 3.3
AI: 0.1
HI: 3.2

Going from 5.1 down to 3.3 may not seem like much of a change just by looking at the numbers, especially if one compares them to stats that would appear when not using a CPAP. However, I feel significantly better. On Thursday I felt moderately rested. On Friday I felt well rested. It’s a huge improvement and one that will improve my overall energy levels, if I can maintain or improve these numbers.

Note the higher leak rate. This may not be a negative indicator. I’ve changed masks so it probably has a different, expected leak rate than the Quattro (I may need to adjust a setting in the CPAP itself to account for this within the mask type settings, though the Quattro is probably similar in this respect – I probably won’t change it). Also, it was only the first night that used the mask.

I think I have the ability to improve these numbers. For one, it took me a while to actually fall asleep while I was using the mask. Also, since it’s a new mask I haven’t fully adjusted to it. Even though I did wake up to a high leak alarm for the first time in months the treatment was still more effective than those of the past couple of nights that I’ve recorded the stats for.

Numbers aren’t everything. They can serve as good guides but they’re not absolute indicators of treatment effectiveness. I’ve read several posts that stating that ResMed machines report numbers slightly higher than other machines. Some posts have mentioned that the ResMed machines may be more sensitive to events than other machines.

Regardless, one of the most common pieces of advice that I’ve read countless times in the forums is to consider how you feel as being one of the most important indicators of how well a CPAP is working.

Updated 05/20/2012: I added a new post about the limitations of relying solely on CPAP machine stats to gauge treatment effectiveness.

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