frustrated re: lack of improvement w #'s

RG wrote:Velbor posted an interesting chart about the differing definitions for three of the manufacturers:

Yet, according to that graph, the definitions for hypopnea are actually the same- >50% flow reduction.

Further, Velbor's chart does not mention that A10 also looks for flow limitation and /or associated snoring, so on the surface it would seem that the Respironics algorithm would report out more events than A10.

RG wrote:

Muffy wrote:Has a comparison actually been done?

Not any formal scientific comparison with live people that I know of. It's purely anecdotal.

Then could it not be possible that A10 is, in fact, accurate, and that the correct assessment is that the Collective Mind of the Forum simply could not solve the problem?

I would think that those events that are arbitrarily dismissed in the A10 HI bucket need at least some sort of explanation. I mean, the machine went out of it's way to say that there has been a change in breathing. To say that "Well, half of those events are benign" without at least some explanation why that might be could be bypassing some important clues to potential improvement opportunities.

Now, it may very well be that in at least some of these cases, A10 has overscored (and it could just as easily be all of the hypopneas, if there is indeed, a "loophole" of sorts). And while I do believe that such a loophole exists, I don't believe that it occurs in all ResMed users.

So, before going any further, the first question to ask of RM is:

"Are you satisfied with your sleep right now?"

Muffy

RG wrote:

Muffy wrote:Has a comparison actually been done?

Not any formal scientific comparison with live people that I know of. It's purely anecdotal.

Although I have not addressed algorithmic issues, see my recent post
viewtopic.php?f=1&t=42646&p=394522#p394522
for a detailed discussion of respiratory event index comparisons between ResMed and Respironics machines.

Mr. Velbor.

I have recently had the opportunity to observe a patient with highly erratic breathing noted on NPSG, that when placed on a ResMed unit, exhibited a relatively high HI (and AI, for that matter). Arguably, there were few "scorable events" in NSPG, as well as confounding wake and sleep transition. Close examination of the defining window(s) for the determination of the calculation of "baseline" (key to hypopnea identification) is pending.

However, I believe that "erratic breathing" is the key as to why some ResMed users exhibit higher relatively high(er) HI when compared to Respironics. I am hypothesizing that it is the Variable Breathing Controller in the Respironics algorithm that acts as a filter for erratic breathing. As I understand the operation of the VB Layer, event scoring is suspended. Without this filter, events are scored, as would be seen in A10.

If this theory is correct, then patients with HI Respironics < HI ResMed will also have a significant degree of Variable Breathing. Interestingly, as you had noted before in:

viewtopic/p394843/viewtopic.php?f=1&t=3 ... ng#p374873

it appears that your VB% ranges from at least moderate to occassionally very severe.

Muffy

I have a similar problem. I've been on CPAP about 3 months. No matter what I try I still have a poor AHI. About a week ago I managed to have a night with AHI of 4 then 5. The last two nights with the same mask my AHI was 16.5. My doctor suggested iron supplements for my PLMD. I also tried tonic water to see if quinine works. During my sleep study my AHI was only 21. I'm using a Devillbiss Intellipap. I don't have the software only the readings from the Smart Code. It's pretty depressing.

Muffy wrote: I am hypothesizing that it is the Variable Breathing Controller in the Respironics algorithm that acts as a filter for erratic breathing. As I understand the operation of the VB Layer, event scoring is suspended. Without this filter, events are scored, as would be seen in A10.

This is a truly fascinating hypothesis!

Other than from occasional posts on this forum, I have absolutely no information about Variable Breathing. The impression which I had gathered was that "Variable Breathing" was a "concept" with which Respironics had been working, that they had a construct for "measuring" its occurrence, but that they otherwise did nothing (at least not in the conventional xPAP machines) with that information. Encore software provides a total time in Variable Breathing, but otherwise displays nothing regarding it. The .xml file time-stamps the occurrence of VB in their usual 30-second window format, as for other events.

I was under the impression that there was no VB "controller" or VB "layer". The notion that recording of other events is "disabled" during times of Variable Breathing is new to me. [EDIT: I've seen this described in one of the Respironics patents, but had never before encountered evidence that this had in fact been implemented.]

I typically simply ignore VB data in the .xml file. On the basis of you suggestion, I randomly chose a recent file (8/10/09). During that night, on a Respironics M-Series Auto, in auto mode with limits of 10 and 20, I re-looked at my data. AHI was 2.4, comprised of AI 1.4 (11 events) and HI of 1.0 (8 events). In addition, Flow Limitation index was 0.6 (5 events) and Vibratory Snore index was 3.2 (26 events). Variable breathing was reported as occurring for 2:37:00 out of a total blower time of 8:01:48, or 32.6% of the night.

A review of the event time-stamps revealed that NO apneas, NO hypopneas, and NO flow limitations were recorded in the same time windows as Variable Breathing. (These events were frequently noted immediately before or after VB notations.) Overlap was seen with Vibratory Snore: of the 26 recorded events, 5 of them were coincident with Variable Breathing reports.

[EDIT: I've since also reviewed my VB data from last night. Roughly the same large-scale patterns. Again, NO apnea or hypopnea or FL coincident with VB; but several short breaks in long strings of VB's with apneas or hypopneas poking their heads through.]

My fast and informal review of a single "randomly chosen" night of data is supportive of your suggestion. I will try to develop some tools to look more closely at this matter. If you are correct, if Respironics machines "ignore" other events during Variable Breathing, many of us will all need to re-think how we think about Respironics reporting conventions. The "standard" may not change, but the meaning underlying it may change significantly.

If you have additional documentation regarding how Respironics identifies or uses Variable Breathing, I would be grateful if you could share it, publically or privately. I would also ask other "tech-savvy" members to weigh in on this matter.

Thank you, Muffy, for sharing your valuable knowledge and insight. Blessings, Velbor

While the Variable Breathing Control Layer was discussed in the early RIC patents, in March 2007 there appeared Patent US 7,186,221:

Positive Airway Pressure System and Method for Treatment of Sleeping Disorder in Patient

This Rapoport-Norman patent recognizes the existence and importance of "troubled wakefulness". This certainly represents the progression of the Variable Breathing concept. While it does not say specifically that Encore Pro is not going to report out events during state iv, I think this lends strong support that that may be in fact what is occurring.

Muffy

Muffy wrote:While the Variable Breathing Control Layer was discussed in the early RIC patents, in March 2007 there appeared Patent US 7,186,221:

Positive Airway Pressure System and Method for Treatment of Sleeping Disorder in Patient

Here's a patent for RIC issued 1/30/07 for an APAP that mentions 'variable breathing' multiple times: http://www.patentstorm.us/patents/7168429/claims.html

Interesting topic!

To prevent this important topic of Variable Breathing from potentially being lost in this thread, I have initiated a new thread:

viewtopic/t44325/ResMed-vs-Respironics- ... thing.html

which I would recommend for continuation of this discussion.

With great gratitude to Muffy. Velbor