Auto Versus (regular) CPAP w/CFLEX

[Guest]

Here's a link where you can access the rules for engagement (a.k.a. the patent) for the Respironics Remstar Auto (many thanks to derek):

Respironics patent


More info can be found in the following link (many thanks to Grabraham):

http://www.lickthewindow.com/remstar/

[rested gal]

Ellen, you did the PM correctly. To see if any PM's have been sent to you (one has..I sent a reply.. lol) look up at the upper righthand side of this message board page. Up in the blocks that say "FAQ Search Memberlist etc." the far righthand one says "You have 1 message" or whatever. Click that.

[rested gal]

Is there a document somewhere (PDF file?) that describes the "rules of engagement" for the AUTO? I'm VERY interested to know how this works exactly.

guessed, you asked questions I don't know the answer to. I was struggling with my "NR" explanation, trying to recall what I've read a poster nicknamed "-SWS" write about how the REMstar handles "non-responsive" events.

Probably I should have just looked for some of his old posts about NR's instead of floundering and confusing the issue myself. Sorry about that!

Still can't find exactly what I was looking for by -SWS, but this comes close (see RG flounder there, too! LOL!! ):

Feb 21, 2005 subject: Remstar Auto - Non-responsive events? Three page discussion of Remstar Auto flagging "NR" events.

[Guest]

The following is is from this link:
Respironics C-Flex, Remstar Auto with C-Flex, Remstar Pro 2 with C-Flex Interview

The REMstar Auto algorithm looks for apnea’s that are non-responsive to treatment which could indicate that these are central events. At any pressure 8 cm H2O or higher we will make three pressure increases in response to a sustained string of events. If there is no improvement after the third increase, indicated by the persistence of events, the pressure is dropped 2 cm and a constant pressure is held for several minutes. If there is snoring noted during this period of constant pressure, which would indicate obstruction, we will increase pressure and reset the non-responsive treatment, thus allowing for three more pressure increases. Apneas can potentially be treated up to the device's maximum pressure setting (20 cm H2O).

[Ric]

Thanks RG, DVL, Guest, Guessed, Guest, and Guest for all the deep answers to the deep questions, and the reference material. Also thanks doovid, ellen, twilson, and WTTM for asking all the right questions and the commentary which elicited all the deep answers. (hours of reading if you drill down on the reference material). I especially enjoyed reading (watching) the PPT about "Not Every Patient Needs to Go to the Sleep Lab". I'm convinced that APAP is revolutionizing sleep therapy. Especially considering that CPAP + PSG is actually more expensive than self-titrating APAP. Also to hear an M.D. present the notion that "inappropriate" CPAP is harmless, unlike delayed/denied "appropriate" therapy. That was very enlightening. Also "rules for engagement". Stuff my mom never taught me. Should be required reading for.... everybody.

[Darth Vader Look]

rested gal wrote:
One small clarification. On the Encore Pro data, "Non Responsive Apnea/Hypopnea Events" refers to Apneas and/or Hypopneas that do not respond to 3 small increases in pressure. In other words, the apnea or hypopnea persists despite the REMstar Auto giving it some pressure nudges to try to clear it. Couldn't clear it. The machine stops trying to use more pressure against a "non responsive" event in case it might be a central apnea.

... So after 3 test nudges of more pressure, the REMstar Auto decides to treat the event that won't respond to pressure as if it were a central.
Not seeing any "NR"'s ticked on the Encore Pro graph simply means the machine didn't run into an event for which it tried 3 little pressure nudges that accomplished nothing.

Can we assume that after it has bumped the pressure by "3 nudges", and it is still up by "3 nudges", it might detect yet another "event" and give it (as many as) 3 more nudges? Otherwise, how will the pressure ever get more than 3 nudges above the baseline? How long does it wait?

I may be confused, I'm not sure the "tick" marks you refer to are the same as the numeric data Ric was referring to in the row labeled "non-responsive events". Looking at my EncorePro detailed report, I see lots of OA and HI tick marks (on the graph), but I take those to be "compensated", or as you say, unworthy of more pressure. Whereas,
the numeric data shows a "0", which I took to mean it was successful. Are we talking the same data points?

This is good information. Is there a document somewhere (PDF file?) that describes the "rules of engagement" for the AUTO? I'm VERY interested to know how this works exactly. THANKS !!!!

Correct me if I'm wrong but the Respironics REMstar Auto patent PDF file on pages 11 and 12 spell out how the algorithm handles the sensor input for a detected hypopnea and/or apnea event. Rested gal is sort of right in her explanation of it but it goes deeper than that and is why we set up the Auto unit the way we do. The setting I like to set mine to is 3cm below and 3cm above the titrated level which I believe most of us do. People with their titrated value at or below 11cm have the added advantage of being able to set their lower pressure level at 5 to 6cm. The disadvantage here is that if your lower pressure level is set this low, your titrated level is say 10 or 11cm and the unit senses an apnea event, it may take too long to resolve the event, thus waking you up, something that you don't want to happen.

This is my interpretation of how this works and it may be missing some timing periods based on wave shaping. The Auto will upon detection of an event determine whether it is an hypopnea or apnea based on past percentages of breathing patterns. If the lower pressure level is set below 8cm and the beginning of an apnea event is sensed, the unit increases the pressure level up 1 cm increments smoothly and monitors the breathing pattern. Increases are made to the 8cm level or until some sign of clearance of the obstruction is detected, whichever is less. Once the 8cm level is reached a 3cm bumping rule comes into play. Therefore, upon reaching the 8cm level, the highest level that the unit will go to if an apnea was sensed is set to 11cm (3cm above the 8cm mark) or the high end pressure limit, whichever is less.
Just as a side note this tells me that the highest pressure level setting should really never be less than 11cm when in Auto mode.
The pressure limit will be raised smoothly from 8cm (by 1cm increments) until it hits 11cm or the obstruction is cleared, whichever is less. If the upper limit is set to less than 11cm (say 10cm) the unit will stay at that level (10cm), can't determine whether the event is a central or not due to the 3 bump rule not being carried out fully and remains at that 10cm until the obstruction clears. This is my reasoning for the high pressure level in Auto mode not being set less than 11cm. Of course if your titrated level is 11cm your high pressure limit will be set at 14cm.

Therefore, if we assume the high level setting is 14cm and the pressure goes up to the 11cm level and no clearance of the obstruction is sensed the unit will determine that the apnea event is a central and will immediately drop 2cm and hold for a period of time. If the unit detects some clearance of the apnea event at its upper limit, it will remain at that level for a period of time. Once the event is cleared the unit will drop smoothly in 1cm increments down to the lower pressure level setting or until it senses another apnea in the making. If the apnea was determined to be a central (hence the unit drops the pressure from 11cm down to 9cm) and the apnea doesn't clear but starts to get worse or a snore is sensed, the unit will bump up to 3cm again. In this case it would go to a maximum of 12cm.

Now if your titrated level is higher than 11cm, you should set your lower pressure level to no more than 3cm below that value. My reasoning here is that should the machine see an apnea event start it will smoothly increase the pressure level up only 3cm and if your titrated level happens to be higher than that, it may not clear the event without waking you up, hence what we want to prevent in the first place.

Now if your pressure level was titrated at 13cm, accordingly you would set your lower pressure limit at 10cm minimum and the higher pressure limit would be set to 16cm. An apnea event is sensed as starting to happen. The unit increases smoothly in 1cm levels until 13cm is reached or the apnea is event is cleared. At 13 the unit decides that the event is a central and immediately drops 2cm down to 11cm for a period of time.

The unit senses a snore or the apnea getting worse. The 3 bump rule comes back into effect allowing the unit to reach 14cm before determining if the apnea is a central. At 14cm and no improvement the apnea is determined to be a central and the unit drops the pressures down 2cm immediately to 12cm. This could continue until the pressure hits the upper limit of 16cm set.

Of course there are going to be other issues such as mask leakage, wave shaping and timing periods that will have an effect on the overall performance of the algorithm.

[rested gal]

I especially enjoyed reading (watching) the PPT about "Not Every Patient Needs to Go to the Sleep Lab". I'm convinced that APAP is revolutionizing sleep therapy. Especially considering that CPAP + PSG is actually more expensive than self-titrating APAP. Also to hear an M.D. present the notion that "inappropriate" CPAP is harmless, unlike delayed/denied "appropriate" therapy.

That's one of my favorites, too, Ric. We can all thank Mikesus (his nickname on this message board, "Mike" on the ASAA board) for first posting the link to that PPT presentation by Dr. Phillips.

Ideally, everyone with EDS (excessive daytime sleepiness) would simply get a full PSG sleep study done. Conducted perfectly, scored perfectly, etc. But in the real world it's not always that way. Many people with OSA cannot afford a study and will never get one...especially the uninsured.

Some who forego a full PSG study will have other sleep disorders (PLMD, for example) that will not be identified and could be disrupting their sleep in ways that no CPAP machine of any type could take care of. But the vast majority who have obvious symptoms of OSA probably do have "just" OSA and certainly could benefit from getting treatment as soon as possible. An auto-titrating CPAP (autopap) being the best way to go about treatment lacking a PSG, imho.

If the clinical signs are there and a full PSG is out of the question, then it's better to at least try a 2 pound machine than chance having a 2 ton machine go across the center line....just for lack of a little more air at night.

[NightHawkeye]

I especially enjoyed reading (watching) the PPT about "Not Every Patient Needs to Go to the Sleep Lab". I'm convinced that APAP is revolutionizing sleep therapy. Especially considering that CPAP + PSG is actually more expensive than self-titrating APAP. Also to hear an M.D. present the notion that "inappropriate" CPAP is harmless, unlike delayed/denied "appropriate" therapy.

That's one of my favorites, too, Ric. We can all thank Mikesus (his nickname on this message board, "Mike" on the ASAA board) for first posting the link to that PPT presentation by Dr. Phillips.

Ideally, everyone with EDS (excessive daytime sleepiness) would simply get a full PSG sleep study done. Conducted perfectly, scored perfectly, etc. But in the real world it's not always that way. Many people with OSA cannot afford a study and will never get one...especially the uninsured.

Don't forget about those of us who have clustered/intermittent apnea which may not show up or show up only as low AHI during PSG's. We are normally precluded from treatment using the standard protocol.

I feel kinda like a poster child for APAP. I had two PSG's done, separated by a dozen years or so, both indicating I didn't have apnea. Without any help from my sleep doc I got an oximeter to make measurements while sleeping at home, and like, "Whoa! What's this?" Upon seeing the data, my sleep doc wrote me an xPAP prescription. The machine confirmed the apnea and I've slept much better since. My general health has also improved. Some nights I don't have any apnea at all. Some nights the APAP goes up around 12 cm or so. Gotta love it.

Regards,
Bill

[Guest]

Being new to all this, I may be very ignorant of all the studies and threads that have flowed about this issue over the last decade!! I just want to be sure that I'm getting the best treatment for my sleep apnea... Can anyone point to a definitive medical study that supports their recommendation of an auto vs regular CPAP machine?? And if so, is it also safe to say that there is another report out there that recommends the opposite!!? Help!

Doovid, are you still with us? Did all the linked medical studies answer your questions? We haven't heard back from you and I'm worried you may have slipped into an information-overload-induced coma! Either that, or you're still wading through all the data. Ric is right, you've got hours of material to read. But, that's a good thing, right?

[Doovid]

I'm still here. Didn't get to visit this forum until today so was surprised (thrilled?) to see all the indo, comments, etc. I see a lot of reading ahead considering all the articles and other info provided!

This data should be very helpful in getting knowledgeable of all that surrounds APAP versus CPAP. Perhaps I shouldn't think that my sleep study is utlimate!! And when I think back to it, it can not be considered a normal night's attempt at sleep, There were too many unusual events, like all the wires, interruptions , etc. that took place.

I've been through 4 sleep lab visits over the last 4-5 months. My final sleep test was complicated due to my coming down from taking very strong dose of Oxycotin for a untreatable pinched nerve in my neck (causing high level-9 pain). In fact, when I went for my first lab, my results were quite different...I was diagnosed with high level central apnea and pressures were set at 20cm!!! I went for several other lab rests due to inconclusive results. It was not until, my doctor considered the impact of the meds on my sleep lab results that I went for another one, after slowly cutting out the pain meds! My pressure is now set at 10cm. So it's very possible that my results are still not exactly correct due to residual meds and all the other unusual things we all go through at the sleep labs...

In my case an auto CPAP may be the answer... Now to do all the reading presented to me!