What is the REMStar Auto really doing?

[rested gal]

My comment really doesn't have anything to do with what you all are talking about - I'd be the world's worst at trying to correlate "this" with "that" on data charts.

When it comes to wondering if there's much point in having an autopap if a person needs to raise the bottom pressure up pretty close to their titrated pressure to get good treatment, I think Wader made an excellent point:

The auto will still provide the ability for the machine to prevent obstuctions that require pressure higher than our titrated pressure.

Again and again we read of people who didn't feel good during their first months on cpap until their doctor (in a guesstimate, really) upped their pressure a notch or two. Or people who had been feeling good on cpap beginning to have the old sleepy symptoms creep back in over a period of several months. And people who were sent back for yet another expensive titration night at the sleep clinic just to find the pressure needed to be raised a bit more.

Those things alone still make an autopap the way to go, imho. Just because an autopap can be set for a wide range doesn't mean setting it "as low as we feel comfortable breathing at while awake" is ideal for all of us. The real value of an autopap, especially when coupled with the software to monitor our results, is in being able to tailor the treatment to each person. Some might do fine with a very wide range, some might need a very tight range. Some might need the lower pressure kept up close to titrated pressure but can have the top "wide open", others might find the reverse to work better.

Autopap, software, and most of all (imho) the feedback from our own bodies in the morning, can help us work out good treatment. I know that for awhile I'd get so intent on comparing my AHI of 3.0 on one night with an AHI of 1.0 on another night, trying to pin down the reason... I often forgot to take into consideration, "How did I feel that morning and the rest of that day?"

Perhaps others do have significant differences in how they feel depending on whether their AHI is 1.0 or 3.0. For me, I end up feeling the same - good - as long as the AHI is well below 5.0. Some nights there will be a lot of tick marks, a lot of pressure changes...other nights not much showing up on the graphs. Unless I woke up not feeling as rested as usual, or saw something extremely unusual beyond what I think of as normal variations in the data, I won't worry about why the data often looks different from one night to another.

Nonetheless, even after a year, I still like to look at it often. And am very interested in reading how others interpret their data. I do love learning.

[derek]

Excellent points Rested Gal, I agree with you one hundred percent on it's all about how you feel. However to take up Wader's point,

The auto will still provide the ability for the machine to prevent obstuctions that require pressure higher than our titrated pressure.

if (and only if ) my conjecture that the REMStar does not respond to isolated events is true, then if we set the minimum pressure to a value that treats most events, the remainder will be so few and far between that the Auto will not respond - and we are back at cpap again

Now if Respironics would just come out and tell us what is going on inside the magic box...

[-SWS]

An observation about my own hypopneas relative to the RemStar Auto (without C-Flex) and the 420e. Both machines seem to trigger very conservatively on my hypopneas that are not concomitant with any other type of obstructive event (if they even trigger at all---I will have to go back and take a look to see if they ever trigger on non-concomitant hypopneas now). I suspect this conservative approach to non-concomitant hypopneas has to do with how difficult central hypopneas would be for any AutoPAP to discern. My RemStar Auto with the new firmware version seems to log more snore than the 420e and it seems to trigger more frequently on my snore than the 420e. Yet, before the RemStar Auto firmware change, the two AutoPAP models seemed to log snore and trigger on snore in a very similar manner. It seems that the RemStar Auto is now a more snore-agressive machine than it has been in the past.

Yet, despite the more agressive detection and trigerring, I now end up with a higher snore index on my new RemStar Auto than I currently do with my 420e or than I ever did with the old Remstar Auto firmware. My snore and pressure response on the new RemStar Auto firmware is very similar to Derek's chart with the higher snore index and the higher pressure response. My old RemStar firmware level never behaved that way.

[Hugh Jass]

if (and only if ) my conjecture that the REMStar does not respond to isolated events is true, then if we set the minimum pressure to a value that treats most events, the remainder will be so few and far between that the Auto will not respond - and we are back at cpap again

Bingo.

My AHI was around 3-4 between APAP pressures of 4-16 (90% was around 5-6)

Since I bumped it up to 9-16 (Doctors suggestion), my 90% is average 9-10 (sometimes goes up to 13 for a few minutes) and my AHI is between .7 and 1.5. On top of that, I'm sleeping better. (Still fatigued though )

My opinion: The minimum pressure is key to appropriate treatment. And my experience has been that the APAP will not always determine what is the best pressure for you to PREVENT apneas/hypopneas. It may be good at RESPONDING, but sometimes it's too late and you've been awakened. It's something that needs tweaking..

[rested gal]

Well, I'm not sure if this helps or not... this graph of one of my nights on the Remstar Auto (not my current with with C-flex) seems to show triggering on every event except the first apnea shown. Prior to that one, it was triggering on quite a few things that it apparently dealt with successfully?

Perhaps SWS and Derek can tell better (I'm not good at trying to correlate events on a graph, even holding up a straight edge!) it looks to me like the machine was triggering on each of the last three flow limitations, perhaps preventing them from progressing into hypopneas? However, is there any way to know if the machine actually was triggering on the flow limitations at those three points, or if it was really dealing with something else it had on its little brain right then?

[-SWS]

Here's a neat trick for visually lining up sleep events and pressure response to see if they are on the same vertical line (hence a likely trigger response): Use the mouse scrolling function to move the sleep event up to the top of your web browser window, so that the sleep event tick mark touches a web browser tool bar. Make a mental note of where that tick mark touches or projects upward. Now scroll the mouse so that the resultant pressure graph is also touching that same tool bar. Much easier to to figure out how horizontal graphs correspond to each other on a vertical-line "cause-effect" basis.

Rested Gal, you had no hypopneas, and hypopneas seem to be AutoPAPs achilles heel regarding trigger. I suspect an AutoPAP's algorithm will try to leverage as much of its hypopnea treatment toward proactive techniques as possible.

I see the first apnea produced no pressure response---hence no trigger. The first four flow limitations each triggered pressure increases. The third and forth apneas produced no pressure increases either. The fifth and sixth flow limitations each produced a slight pressure increase. The last flow limitation accounted for a slightly higher presure increase. The one and only snore produced no pressure increase.

[derek]

So many questions, so few answers. One of the problems is that the events shown are (I think) the ones that "got away" - that is they were not stopped by the "pro-active" algorithms. I don't think that the pro-active blips in the pressure show up on the chart. So maybe the triggers for the pressure increase ar not evident on the chart...

A question from Rested's chart: could it be that the mask leak triggered the rise, or was the mask leak increase caused by the pressure rise? Chickens and eggs. The striking difference in the leak pattern makes me wonder if a leak developed, which then caused the pressure jump.
derek

[wading thru the muck!]

Derek & -SWS,

My question regarding the chicken-egg leak question is do we know based on the flow volume if the rise in the leak graph only correlates to the increased flow relative to the increased pressure rather than mask leaks.

The reason this occured to me is that in the manual for the new aura I have, they have included a graph showing the vent flow rate curve relative to pressure.

My point is do we know if the "Leaks" are not just increased vent flow due to increased pressure?

[-SWS]

...do we know based on the flow volume if the rise in the leak graph only correlates to the increased flow relative to the increased pressure rather than mask leaks.

The reason this occured to me is that in the manual for the new aura I have, they have included a graph showing the vent flow rate curve relative to pressure.

The vent leak rate will increase with pressure. A couple comments or observations, though. The increased leak rate that results from heightened pressure should be a smooth increase with a magnitued that is taken directly from that chart or graph that documents the mask's specs. When you see an unaccountable increase in leak magnitude that may or may not be accompanied by leak-rate oscillation (such as the leak oscillation on RG's chart), then you can suspect that a blow-out or breech has occured because of that pressure hike. If you see a nice smooth increase to leak that is commensurate to the machine's pressure hike, then you see the design characteristics of the exhaust port manifested nicely on your overnight leak chart.

[derek]

Wader,
The flow rate of air through an orifice (which we can assume models the exhaust vent) is approximately proportional to the square root of the pressure.
On Rested's chart the pressure went from 10 to 14 cm, so we would expect the vent flow (baseline 25 LPM) to rise to
flow at 14 cm pressure = 25 x sqrt(1.4) = 29.6 LPM
If you look at her chart you will see a small pedestal in the increased flow to approx. 30 LPM, (which I think is the increased flow) underneath the wild excursions.

So there is something else going on here!!
derek

[loonlvr]

Can someone explain how to import a page from my encore software to show you all a one nites results into this forum.. My ahi is almost never under 10. It could be a good learning experience for me and others. You may have to e-mail me and do it step by step as I m not quite so computer literate.

[derek]

loonlvr,
You somehow have to put the page on a web server. I'll PM you with my email address, then if you can save the report as a pdf file and send it to me I'll put it on my server and tell you how to link to it.
derek

[Guest]

Thanx derek.So u want me to e-mail it to u as an attachment then u will post it?

[rested gal]

I don't mean to jump in and speak for Derek, but yes, that's what he wants you to do. While you're in Encore looking at one of your reports, click the word File at the top and save it as a "PDF" file. Be sure to note what folder it gets saved to. Then email that PDF file to Derek as an email attachment.

[rested gal]

I don't think I'll post any more of my charts since "the wild excursions" (as Derek says, LOL!!) show up so clearly!

That was, NO DOUBT, when an edge of tape flopped loose.

Darn, I think I'm making it worse.