Question about OSCAR accuracy during high leak periods

[raptosnorus]

Hi all -- newbie here, one month into CPAP life, trying my best with Airsense11, F20 & OSCAR to make adjustments to get things right with my pressure range, mask size/type/fit, sleep positions, and all the other variables...

My current question: I'm wondering how much to discount the data in OSCAR during periods when the mask is leaking significantly. It's been suggested to me that the CPAP itself may be missing AH events during such periods because the leaks can obscure things, which makes sense, but when I look at the flow levels and other info in OSCAR, nothing else suggests a gap in what's being recorded. It looks as if it's recording the leaks and also continuing to record everything else going on with respiration, flow, events, etc. 

I realize -- as the second attached OSCAR screen clearly shows -- that AHI often goes up during big leak times, but there are other high-leak times that everything else *seems* to be OK (i.e. low or zero AHI), such as between approximately 7AM-8AM, as highlighted in the first attached OSCAR screen.

Last night's data is from a (not very successful) tryout of the large size mask instead of the medium. It's more comfortable on my face but was clearly was tough to control leaks with. I'm trying to gauge whether it would be OK for me to wear it, leaks and all, if the leaks themselves aren't causing me noticeable discomfort, and *if* I could find a way to keep AHI low even with leaks above the red line. Or is the data itself unreliable-- and is living with big leaks an all-around unwise idea to consider?

Hope my question is coherent, and huge appreciation in advance for any thoughts/info/gudance!

[Crimson Nape]

Hi raptosnorus!  -  

First, OSCAR only reports the data your CPAP records.  If you are seeing large leaks, at least 2 things can occur. One is the leak is so large that your CPAP is unable to maintain proper therapy pressure.  The second is periods of large leaks inhibit the CPAP from properly detecting actual events.  We always advise to first get your leaks under control before anything else.

One other item. The Resmed uses the Flow Limitation to determine a pressure increase. Based on your current flow limitation, your CPAP will probably go your maximum set pressure.

- Red

[Sleeprider]

Turn on EPR full-time at 3 and fix your mask leak. This will get better when you ease the flow limits.

[raptosnorus]

Thank you! I went back to the medium mask and and am doing my best with it; not the most comfortable, but leaks are back to low/normal levels, so that's good. 

Also, I will give the full-time EPR a try, as you suggest. I had turned it on for ramp-only because I had read elsewhere (on myapnea.org, I think) that it's generally a bad idea for most people because (1) its effect is to lower effective CPAP pressure, potentially causing it to drop below therapeutic levels, and also (2) that it increases the amount of air you're taking in, resulting in CO2 levels dropping and a possible increase in central events. Since I'm not aware of discomfort from exhaling against the pressure, it seemed like the safer bet to turn it off. But it sounds like in your view that it could be helpful to me in terms of getting the pressure right, so I'll give it a shot and let you know how it goes!

[Gideon]

Rant: I hate the idea to not use a feature just because you might, not will, only might see something bad.

By that thinking why the h*** are you even trying CPAP therapy? You do realize that any CPAP will improve your breathing and thus might flush out too much CO2 which might cause CSA. By that standard no one should ever even try the gold standard for apnea treatment, Cpap in any of its flavors.

IMHO try it, if the results are negative then react and correct them. This based things on facts, not mights, conjecture, or guesses.

To be clear, if any of us here see an issue this something like too much flushing of CO2, we will react to it, we just don't assume it will be bad.

Ok, enough said.

[raptosnorus]

Ouch - and rant well taken. 

As I said, I do plan to try it.

In my newbie ignorance, I wrongly believed that the sole purpose of EPR was to improve comfort. Since I was not feeling any discomfort from breathing against the pressure -- and since the arguments about the allegedly modest risk of possibly lessened efficacy with EPR seemed rational to me -- I saw it as a matter of weighing a small risk against no benefit.

I stand corrected. Thanks for taking the time to help me out.

[Gideon]

The rant was not against our members here, it was against those I consider to be spreading that misinformation.

[Sleeprider]

Raptosnorus, my observation was that your 95% flow limit was 0.30 in your posted chart. That is an extraordinary airway resistance that EPR can mitigate by supporting inspiration with increasing pressure against increasing resistance. EPR makes your CPAP a functional bilevel machine with up to 3-cm of pressure support. I did not explain my rationale, but hoped you would try it. Some years ago we wrote this wiki on flow limitations that shows how EPR can quantitatively and qualitatively improve flow limitation and its consequential arousals, hypopnea and snoring. Compare these graphics and observations against some of the unsupported opinions you might have seen elsewhere. https://www.apneaboard.com/wiki/index.ph...limitation

[raptosnorus]

Thanks very much-- that makes good sense. I've got my settings EPR settings changed accordingly and am hoping for better results tonight.

[SideSleeper]

If mask leaks are a problem with the F20 cushion AirFit, have you tried the F20 Air Touch? It is foam and the seal is different. Many of us using this mask have discovered it needs to be worn quite tightly, however. I have eliminated mask leaks almost entirely with it--but can't tolerate the Air Fit.