Experiments on RemStar Snore Detection...

[wading thru the muck!]

Most likely the only option is to increase the minimum pressure. This should not have a negative affect of your AHI. In some people I think there are other physiological conditions causing the snore that cannot be resolved totally with cpap.

[loonlvr]

Good suggestion. Would be nice to know what indices are reasonable for snores, mask leakage, ahi etc. I know they vary with each person and each nite.

[glassgal]

Hi Loonlvr,

Wader, correct me if I'm wrong here, but don't the algorithms vary with different brands of machines and some weight (and respond to) snores differently than others?

Just a thought and question?

Jane

[wading thru the muck!]

Jane,

You are correct! Although I'm sure each one of the manufacturers would claim that there machine handles snores correctly, it seems when it comes to autopaps sound people respond better to some machines. That being said, there seems to be people who have difficulties with each machine and people who have success with each machine. For the most part though most people have no trouble with any of the machines. As far as this snore topic, we are just picking nits here. Just fooling around to get the optimum therapy.

[littlebaddow]

This is a fascinating debate. As a fellow user of the Remstar, thanks derek for sharing the results of your experiment. I admire you're curiousity and persistence!

As a long term heavy snorer with a long suffering partner, we are both relieved that the quantity and volume of my snoring has been dramatically reduced by the use of APAP.

Strikes me, though, that loonlvr makes an excellent point. Does it matter if I still snore Fortunately, in my case APAP has helped with both, but given the choice I would rather have a low AHI and still snore. The short term annoyance of my wife is probably less damaging to my health than the long term effects of OSA.
Hmmm, I may want to reconsider that last point...

[Mikesus]

Well in my case I ended up raising the lower limit and the upper. It was a combo of both that lowered my ahi and my snore. From my limited understanding, when you are looking at the pressure graph, you shouldn't see the machine riding the bottom or the top line. If it is, you don't have one of the ranges set. Muck? (By doing this btw, I went from an AHI of 4.4 down to 1.8 for a 2hr nap, Hopefully it will stay that way for 8hrs. Bad part is the range is 8.5 - 16!!)

[Guest]

Since the topic of snore came up recently, I wanted to bump Derek's experiment back up to the top.... also because I missed this very neat thread altogether when I was recently on vacation. Before going on to comment more directly on the snore topic I wanted to share one interesting tidbit about my own snore on the Remstar Auto. I had one of the early Remstar Auto machines without C-Flex. It typically recorded my own snore index at under 1 or 2 per hour. A little less than a year ago that Remstar Auto developed a problem and had to be sent back to the factory for repair. That repair consisted of a new blower motor and a new main board with the latest, greatest firmware before C-Flex was ever released on the Remstar Auto. Interestingly, with that new main board and new firmware my Remstar Auto (without C-Flex) snore index all of a sudden jumped to around 8 to 12 events per hour! That was a sudden change and the only sudden delta in the equation was a machine change. Quite possibly one of those machines either under-detected snore or over-detected snore----but I suspect Respironics just may have changed their snore logging criteria. That seems to match the anecdotes we read a lot lately about the Remstar Auto leaving plenty of snore logged on the overnight Encore graphs.

I also notice my current Remstar Auto logs more snore in Encore Pro, flat-lined at my minimum pressure than the 420e does flat-lined at that same minimum pressure. So to answer the question about whether those snore tick marks in Encore Pro are as worrisome as unaddressed apneas and hypopneas: I think that they are very likely not. I do believe that the Remstore Auto does not indescriminately trigger on snore, but likely snore-triggers with criteria, which Derek's experiments bear out. Snore tick marks are snore tick marks, and if the snores corresponding to those tick marks do not cause either sleep disturbances or desats, then in my opinion elevated pressure is without basis. However, I also think it's possible for any AutoPAP to misdetect/underdetect/overdetect sleep events, and I think Derek's experiments nicely bear that out as well. So if you experience excessive snore that wakes you up, it just might be time to tweak your AutoPAP pressure range.

The other issue that I wanted to bring up about snore is that I believe there are two types of snore for patients on xPAP. The first type is what i refer to as "primary" snore. It's that snore most of us excelled at before we ever got around to positive pressure treatment. The second type of snore i refer to as "residual" snore. Those are the snores that occur despite receiving positive pressure airway support. Most of this "residual" snore would have likely manifested as more severe obstructive events (i.e. apnea or hypopnea) had we not been receiving positive air pressure. I strongly suspect that first type of snore ("primary") and even a certain amount of that second type of snore ("residual") tends to show up on your overnight charts while you are receiving minimum or lower pressures. I suspect the snores that show up while you are receiving higher pressures tend to be exclusively that second type of snore ("residual"). Primary snore is often proactively addressed by slightly raising your AutoPAP minimum pressure----but with the caveat I mentioned above (the caveat about adding pressure but perhaps accomplishing nothing relative to sleep disturbances or desats). An AutoPAP's maximum pressure might need to be raised if residual obstructive events of any type (snore includude) are unaddressed at the AutoPAP's current maximum pressure.

Last but not least Derek's experiment of rubbing the hose might even show that yet other accoustical events (including cough, sneeze, talking, grunting frequencies not represented in this experiment) can conceivably fool an AutoPAP as well. Nothing's perfect----not even AutoPAP. Sometimes choosing an xPAP platform is a matter of discovering which imperfect machine type suits our needs best. I have run two AutoPAP models now with better results than fixed pressure.

Derek's experiment was really very cool!

[-SWS]

"Guested" once again...

I had one of the early Remstar Auto machines without C-Flex. It typically recorded my own snore index at under 1 or 2 per hour. A little less than a year ago that Remstar Auto developed a problem and had to be sent back to the factory for repair. That repair consisted of a new blower motor and a new main board with the latest, greatest firmware before C-Flex was ever released on the Remstar Auto. Interestingly, with that new main board and new firmware my Remstar Auto (without C-Flex) snore index all of a sudden jumped to around 8 to 12 events per hour! That was a sudden change and the only sudden delta in the equation was a machine change.

I also wanted to mention that my factory-replaced blower is considerably noisier than my original blower... and I wonder if that highly variable noise ever gets misdetected as snore. I admittedly doubt this possibility as I think that louder blower noise is within spec, and quite tolerable. The way to find out for sure would be to run an experiment in the vein of Derek's nifty experiments: vary my own breathing while awake, avoiding all snore noises, then check the Encore report for falsely logged snore that I might attribute to blower noise. The only problem is: as fascinating as I found Derek's experiments to read, if I had to sit there and perform my own, I'd probably fall asleep and start snoring to high heaven!

[2listless]

I decided to revive this series of posts after conversing with Derek. As Rested Gal will attest, I have consistently complained about the snore index. It would be in the high 20s and low 30s. My sleep study and titration study both indicated that I had NO SNORING (which is completely against everything you read!) In using the Remstar Auto with CFLEX with a FP passover humidifier and oxygen fed into the humidifier, my snore index went off the walls. No amount of tweaking, adjusting etc helped. I finally attributed it to a very noisy oxygen concentrator which literally vibrated the floors. Concentrator was eventually replaced with a newer quieter model and snore index dropped down to low 20s after an initial drop to 8.(after discovering it was being fed in incorrectly!) The snore index still bothered me. DH keeps telling me I do not snore...figured he was lying because after 40 years he knows when to keep his mouth closed! I started to think the 2 hoses (remember passover humidifier) were rubbing together so I put up the Great Wall of China between them.....snore dropped into high teens. Eventually oxygen concentrator was removed....snore index DID NOT DROP any further. So I just let sleeping dogs lie for awhile. Well, a lightbulb went off in my head the other night while not sleeping. I took the card and looked at the download.....even the entire time I am awake, it is ticking off snore events and slowly elevating pressure. So, I thought the hose is rubbing against the edge of the furniture......so I made padding out of towels to put between the hose and all surfaces, got back in bed and tried again. Waited about 10 minutes...DH slept through all this of course....got up and downloaded again. NO CHANGE...but same event....snore index raising pressure levels. Now I am really aggravated....so I looked at the entire setup and finally thought hmmmmmmm! I disconnected the passover humidifier and fed the hose directly into the machine....removed the humidifier and extra hose from the area....left up all the padding and the Great Wall of China......and went to sleep, finally. In the morning I did the download.....did it 6 days in a row.........snore index had dropped to 7 and lower. I asked Derek if he could explain it....he was not sure other than the algorithym relies heavily on Snore Index. I do not understand the phenomenon but I do know that my pressures are being raised by the Snore Index. It does concern me however, that other people using passover humidifiers, may be elevating their pressures in an effort to lower the Snore Index. I would be interested to know if anyone else using this machine has experienced the problem or would experiment aa little to see what happens. I see the Sleep Doctor on Tuesday....trust me, I will show him the printouts and pick his brain. If this is a common phenomenon, why do they not attach a warning that a passover humidifier should not be used! I have a passover humidifier because that is ALL the DME had.......trust me, next week they will be getting it back! Now, it makes me wonder how "off" my titration levels are......they used a passover in the sleep lab but they still got a NO SNORE INDEX. So experts in CPAP land....any thoughts or suggestions/comments?!
By the way, fireworks did not elevate the snore index. I lay on the hose all the time...wonder if that affects it. I also strangle myself a lot with the hose.....would someone volunteer to do a strangulation test and see if strangulation noises affect snore index?! How about you RestedGal? You like to "play around!"

[loonlvr]

So what you are saying is that the auto not only raises pressure for apnea events, but also snores? I have never really been concerneded about the snore index, as I never thought it was that important(unless one has a bed partner of course.My main interest has always been my AHI and getting it under 10.

[fstanmyre]

Good stuff Derek. I answers a lot of my questions. Still like to know if you can get My Encore to produce a daily chart of leak vs pressure.

[IWannaSleep]

And how is that accomplished. I make adjustments with my machine to lower ahi. Thats my main concern. I m not gonna change pressures to lower snore index if it affects my ahi.

This data explains a lot. Loonlvr, if a person is using an auto, the implication is that their snores could be causing their pressure to go higher than needed. In fact, I have found the pressure to stop my snores completely is higher than the pressure that gives me the lowest AHI. I have also found that increasing my pressure above 9cm causes my AHI to begin to rise significantly. At about 14cm I start getting non-responsive apneas.

Here is what I believe happens for me. Using MyEncore and this snore data, I know it takes 10cm to stop my snores. But, My apneas are at a minimum at 9cm. The snores would cause my auto to increase pressure above my optimum of 9, and by 10 my apneas are increasing significantly. The machine tries to adjust pressure to stop my apneas, but now it's in a pressure range where my apneas are increasing significantly for each increase in pressure. The end result, for me, is the machine in effect runs away by raising pressure to the upper set limit first trying to stop snores and then trying to stop apneas.

I'm now running my REMstar as a straight CPAP, without cflex. I'm getting my lowest AHI's since starting therapy, last night was a record (for me) with an AHI of only 3.5!!!

[derek]

Iwanna,
It sounds that you are in a similar situation to me. My AHI is lowest at 10cm, my snores are almost gone at 10cm, and zonked completely at 11cm. I have settled for straight CPAP at 10cm for the reasons you outlined, and am getting much better therapy than APAP (average nightly AHI of 0.6).

I want to emphasize again that the Respironics patent states that snores are the highest priority event for changing APAP pressure (although they are handled differently above 10 cm). The simple experiments at the start of this thread demonstarte the sensitivity to snores. I don't understand why they do this, because I can find no correlation between the occurence of snores and apneas/hypopneas in my own data... maybe I'm not representative.

derek

[IWannaSleep]

Derek,

It looks like our individual data/testing results confirms the use of snores as the high priority event. I would bet the reason for this is, they are trying to be pro-active and stop an apnea/hypopnea from occurring by predicting it using the detection of a snore. From reading the literature it looks like common wisdom is the occurrance of a snore is the last detectable event before an apnea or hypopnea occurs. Reasonable logic, and maybe it's true most of the time. We're probably the lucky exceptions to the rule.


ron

[ozij]

The following quotes are taken from Resmed's (not Respironics) Three lines of Defence

Snoring occurs when the upper airway narrows. The noise is made by the vibration of the soft or floppy parts of the narrowed airway.

and

Snoring often occurs before obstruction of the airway. Typically, by responding early to snoring, AutoSet Spirit can help prevent apneas.

I would assume this physiolygical logic is what guides Respironics as well.
I wonder if the correlation has ever been checked empirically by anyone!
O.