(08-25-2013 04:50 PM)charliethetuna Wrote: When using SleepyHead, which metrics are most useful to look at to see if the mask choice is effective?
I am a new ASV user, started about a month ago. Started with a FFM, but was difficult as I am a stomach sleeper. Switched about a week ago to a nasal mask. I am much more comfortable and getting more hours in with the mask, but still tired and wonder if I am opening my mouth when I sleep.
What data would I look at, besides AHI events in SleepyHead software to interpret this?
Hi charliethetuna, welcome to the forum!
I use ResScan, but SH would be much the same. I look at the plot of Leak, which in ResScan is a plot of unintentional Leak for every second of the night (the whole session). ResScan always displays the plot of unintentional Leak, but in SleepyHead I think it is an option whether you want SH to show total Leak (unintentional leak plus the designed-in or desired mask venting) or only the unintentional Leak.
For periods of high Leak, I also zoom in closely (until 1 minute or 5 minutes fills the whole screen) and look at the peaks of the High Rate Pressure waveform, to see if there are any signs that the pressure is failing to reach as high as expected during times of large Leak, which would be visible evidence that the large Leak was preventing the machine from being able to deliver as much pressure as it wanted. If the unintentional Leak gets higher than about 24 L/m the accuracy of the machine's algorithm begins to be affected. I think if the unintentional Leak plot gets much higher than 30 Liters/minute the machine may be unable to fully prevent apneas or hypopneas from occurring.
The best mask I have found so far has been the ResMed Quattro FX full face mask when worn with a RemZzz mask liner.
I suspect a chin strap would definitely be required if using a nasal mask on an ASV machine, because the pressure on ASV machines may occasionally jump really high, such as higher than 20 cmH2O.
And even a chin strap might not be enough to stop large leaks, if air escapes through your lips which might get pushed open by a high pressure pulse even if the chin strap keeps your jaw from opening.
ASV machines may need to suddenly raise the inhale pressure to be 10 cmH2O or more higher than the exhale pressure, so the machine can do all the work of breathing for you, when you have a central apnea and stop breathing on your own.
If the patient has Complex or Mixed Sleep Apnea (Obstructive Sleep Apnea in addition to Central Sleep Apnea), treating the OSA may require the exhale (EPAP) pressure to occasionally be moderately high (10 cmH2O or higher), and if a central apnea occurs when the exhale pressure is, say, 10 then the pressure may need to jump up to 20 or higher during inhale. So leaks are likely to occur. Even if your jaw stays closed, if your lips open this may prevent the inhale pressure rising enough to completely prevent central apneas.
Not saying to go back to using a Full Face Mask; only recommending you keep a close eye on your sleep data to make sure unintentional mask Leak is not interfering with your machine's ability to treat you.