What is the REMStar Auto really doing?

That's very interesting SWS, I hadn't noticed the NR apnea. It's doing what Respironics says - starts to climb at the onset of the dense apneas, the NR event drops the pressure and holds it constant for a while, and then the pressure rises again. It seems as if an NR event takes precedence over everyything elese. I wonder if the higher pressure stopped the apnea burst?
Loonlvr - thanks for posting these charts. It has certainly helped me understand more.
derek

Well, thanks for posting it. I thought it might be good for eveyone to see what severe case of OA looks like. I ll do some tweaking with pressure to see the best way to lower AHI. I m gonna raise my low end first for a few days then go with straight pressure of 11. If anything interesting comes of it I d like you to post it.

What an informative discussion!
I'ld like to suggest a slight change in perspective though.

Derek wrote:"It seems as if an NR event takes precedence over everyything elese"

An NR is not a clinical event. It is a sequence of events defined by Respironics. The following is a quote from respironics, presented so as to emphasise the sequence aspect of it. For the sake of clarity, I did drop 6 words from the last sentence.
1. At any pressure 8 cm H2O or higher we will make three pressure increases in response to a sustained string of events.
2. If there is no improvement after the third increase, (indicated by the persistence of events)
3. the pressure is dropped 2 cm and a constant pressure is held for several minutes.
4. If there is snoring noted during this period of constant pressure, which would indicate obstruction, we will increase pressure
5. … thus allowing for three more pressure increases.

Respironics' machine is basically instructed to go slow as it raises pressure above 8, and use snores as an indication of obstruction. The deal is, as Derek already noted: "You snore, we raise the pressure, because it indicates the obstruction we're here to remove. You don't snore, we wait".

If you look at the snore indicators, underneath loonlvrs two apenea sequences, you can see how they correlate with pressure raises. This is actually very clear in his first chart, starting at hour 4. I would guess that some of those snores (e.g. the one just near the 5th hour in chart two), coincided with the machine's instruction to lower pressure, and that instruction took precedence.
This of course raise the questions of
Timing: how long is "several minutes" of constant pressure, and is there a bottom limit in which snores will not affect it?
Precedence: when a snore and an instruction to lower pressure come together, is the snore given precedence (as is should be?)
Mechanics: once the machine starts lowering pressure , how soon can it switch to raising the pressure, because it got new("here's a snore, therefore this is an obstruction") information?

Loonlvr -

You said you are using the Mirage FF mask. Are you really cranking the straps down?

I noticed that my AHI went WAY up (from 2-3 to 7-9) if I OVER tightened the bottom of the mask. I theorized it was due to pushing my jaw inward causing more apnea events. Might want to look at that also...

Facinated Guest, -SWS or anyone else that might know,

How does Respironics define "no improvement" in response to the thre pressure increases?

Is the NR term synonomous with the term central apnea? If so how did loonlver have several central apneas sandwiched in the middle of a dense cluster of obstructive apneas? Can I assume that he began with a full obstruction which was opened by the air splint but, even though his airway was open he did not make an effort to breathe? Or could another explanation be that the cluster of OAs were caused by his airway spasming open and closed with no effort to breathe during the open periods that were long enough to be considered NRs? I guess what I'm getting at is that I'm agreeing with derek's characterization of the Respironics algorithm as being NR dependent. My suposition is that the REMstar auto is missing treatment of loonlvr's OA because he is not responding during treatment with respiratory effort.

Fascinated wrote: An NR is not a clinical event. It is a sequence of events defined by Respironics.

Yes, Fascinated. Thanks for pointing that out! Indeed, an NR is not a clinical event---but is a Respironics defined sequence. However, I believe two perspectives are actually needed to properly view an NR, depending on the stage of analysis. During that first stage of NR analysis, the NR is best thought of as a string of events (with a long single event even being possible). That NR sequence will consist of the initially detected event and any other pressure unresponsive events that happen to occur until that three-increment limit (above 8 cm) is finally reached. I suspect this just may be a single apnea event, but will very likely be several. That is the analysis stage in which NR should be thought of as potentially several sleep events. A single NR tick mark is laid down by the Remstar Auto after the NR recognition threshold has been met. One NR tick mark is registered, yet all apneas immediately prior were really non-responsive as you and the Respironics rep well point out.

The second stage of NR analysis regards scoring, or the final index. The perspective changes: at this point the NR is tallied as if it were a single event, whether it was or not. This numerical treatment is reflected in the final NR index.

On the subject of snore. One interesting observation can be taken from loonlvr's first overnight chart. The fact that there was little intervening snore between scored NR events likely accounts for the relatively long durations before which normal treatment was resumed. Had there been ample snore immediately after the NR threshold had been met, loonlvr likely would have resumed "normal" obstructive treatment sooner. I surmize the purpose of algoritmically refraining from pressure increases would be to avoid pressure-inducing runaway central apneas. Despite the algorithm's attempt at central apnea avoidance there is fair chance that loonlvr still managed to experience a succession of central apneas for nearly an hour-and-a-half during that night corresponding to his first presented chart. That is why I think loonlvr should get back to his prescribed 11 cm fixed pressure and consult with his doctor regarding any data he collects at his PSG titrated pressure.

Wader, NR would imply that patient air flow (breath) measurements failed to meet Rrespironic's criteria---likely very little or no increase in patient-sourced airflow detected (my own speculation).

-SWS,

Do we know if the lack of patient air flow is caused by obstruction or lack of respiratory effort? If in loonlvr's case this circumstance is caused by lack of respiratory effort switching back to a fixed pressure may cause preesure induced centrals. If the lack of flow is obstructuve in nature and the lab correctly titrated his 11cm pressure requirement then the 11cm fixed pressure sould resolve most of his events. Failing that I think he is a candidate for BiPAP therapy.

One side note in this regard, If he switches the machine to a fixed pressure will it still record NRs? If not, would is do so if the machine was left in hte auto mode with the min and max pressures both set at 11cm?

wading thru the muck! wrote:-SWS,

Do we know if the lack of patient air flow is caused by obstruction or lack of respiratory effort? If in loonlvr's case this circumstance is caused by lack of respiratory effort switching back to a fixed pressure may cause preesure induced centrals. If the lack of flow is obstructuve in nature and the lab correctly titrated his 11cm pressure requirement then the 11cm fixed pressure sould resolve most of his events. Failing that I think he is a candidate for BiPAP therapy.

One side note in this regard, If he switches the machine to a fixed pressure will it still record NRs? If not, would is do so if the machine was left in hte auto mode with the min and max pressures both set at 11cm?

Wader, lack of respiratory effort toward distinguishing central apneas is not measured---hence the three-increment pressure limit imposed by the Remstar algorithm. Any autopap model's algorithm (Remstar included) will clearly prove unsuitable for a certain percentage of patients---as with any pharmaceutical or other prescription device for that matter.

If the Remstar Auto is set at fixed pressure, then I personally do not see how the algorithm would be able to log any apneas as NR. I suspect they will all be logged as OA at fixed pressure for lack of a suitable means of distinction. I don't think the algorithm is looking for open-throat cardiac oscillation, but I could be wrong.

Since the etiology and epidemiology of central apneas are challenging to say the least----and not clearly understood by sleep science----we don't second guess their treatment as lay persons. The AutoPAP pressure delta's just may induce loonlvr's central apneas for all we know. Loonlvr needs to get treated by medical professionals versus us head-scratching second-guessing amateurs in my opinion. He is not an easy case of tweaking good therapy to make even better therapy. His treatment should be out of our hands altogether and in the hands of a doctor.

-SWS wrote:Loonlvr needs to get treated by medical professionals versus us head-scratching second-guessing amateurs in my opinion. He is not an easy case of tweaking good therapy to make even better therapy. His treatment should be out of our hands altogether and in the hands of a doctor.

This is what I said in my very first post regarding loonlvr's data.

My concern in his regard is that in those hugh clumps of OAs his O2 saturation may be going dangerously low for quite a long period of time. This is why I said he should seek advice from a qualified sleep specialist. This does not stop us though, from using this experience to discuss the issues involved and come to a better understanding of the auto-pap algorithm process.

SWS, I wondered if it was my eyes deceiving me, but I thought I also saw the NR tickmark hiding in the dotted line.

I know that the prudent recommendation from message boarders would always be to consult the doctor - especially about such heavily apneic results. But who knows if the doctor will really understand them. (Cynical me, I know, I know.)

Without trying to play doctor - but tossing out more food for thought when loonlvr consults the doctor.... SWS, wouldn't this possibly be a case where the PB 420E would be a better autopap of choice for dealing with this specific patient's obstructives? The 420E being the only autopap that allows for raising the default of 10 for "maximum command on apnea" in its advanced settings. Perhaps a trial on a 420E with some judicious tweaking, could reveal more about what is really going on and what kind of machine loonlvr needs. I don't know if a doctor would understand the way the various brands of machines work well enough, though.

Yes, Wader. Good point. These discussions are key to our own learning experience. It's important during these discussions to re-emphasise the words you have just highlighted in your prior post.

I just get worried that some patients here expect to be treated by a committee of their peers!

Thanks again for pointing out your precautionary words of wisdom!

-SWS
I thoroughly agree:

loonlvr should get back to his prescribed 11 cm fixed pressure and consult with his doctor regarding any data he collects at his PSG titrated pressure.

And also about the two pespectives: 1. understanding what happens, and 2. understanding how it is identified and reported

Wader - and -SWS
Neither the remstar, nor any of us can know for sure why any specific apnea did not respond to the pressure - that's why they put that belt around our chests in the PSG: to report muscular effor (of lack of it) during the apnea. All we do know is that loonvr didn't snore within the time interval Respironics set for raising pressure. For all we know, he could have spent that time struggling valiantly to breathe through an obstruction. An apnea could be central, it could be pressure induced central, and to my mind it makes sense that it could just as well be the result of lack of pressure (educated guess, not knowlege).

I would therefore paraphrase -SWS slightly: "loonvr managed to experience a succuession of untreated apneas - and didn't snore within the remstars "time to treat" interval, and parts of this sequence were tagged by the remstar as NRs, prior to a further raising of pressure." So far, the description. As for interpreation: since the pressure finaly continued to rise, and apneas were less on higher pressures, I would say the hypothesis of "pressure too low to open airways in a person with severe apnea" is at least as probable as "central".
And that is why I think -SWS is right: loonlvr should get back to his prescribed 11 cm fixed pressure and consult with his doctor regarding any data he collects at his PSG titrated pressure

Loonvr - you have a table of numbers, below the graphs, telling you at what pressures you had your non responsive apneas. If you still feel like sharing , could you let us know the pressures reported for the NR in those two charts? On the charts it looks like the NR did not occur at maximum pressure, but rather, so to speak, on the way there.

Rested Gal, the big burning question is whether these are central apneas and if so, whether they are pressure induced. They just may be heavy obstructive apneas, in which case setting the 420e with a command-on-apnea higher than its default of 10 cm might have provided loollvr better therapy. If they really are central apneas, on the other hand, the central question becomes whether those central apneas are pressure induced. If so, raising the command-on-apnea higher than 10 cm just may prove counter-productive.

Bottom line: there's no way to easily tell whether loonlvr would fare better on the 420e with those "NR" apneas short of actually trying it in my opinion. I suspect that loonlvr would be a candidate for the 420e

Fascinated wrote:An apnea could be central, it could be pressure induced central, and to my mind it makes sense that it could just as well be the result of lack of pressure.

Yes, Fascinated. I agree. I have highlighted the above words in bold for the sake of our own clarity. Thanks for bringing that out!

Far be it from me to feel I need to get credit for anything that is being attributed to someone else, but since I'm one of the frequent posters who gets critisized for suggesting that people tweak they're own therapy, I'll point out that I was the first on this thread to suggest that loonlvr switch to a fixed pressure therapy.

wading thru the muck! wrote:I agree Loonlvr should show this charts to a qualified sleep specialist. In the interim, could he set his auto to a fixed pressure at 12 or 12.5cm (based on his 90% number) and see if that brings his AHI to an acceptable level.

OK, now you can all roll your eyes at the guy who thinks he's so important.