Very Interesting Article(Long!)

[DoriC]

http://www.sleepreviewmag.com/issues/ar ... -09_02.asp

I don't know if I should be worried but I can't believe I actually read this whole article and understood a lot of it. It answered many questions about the different machines. I used to wonder about people who posted these articles here. Don't they have a life? : Your eyes may glaze over but you'll learn a lot if you stay with it.

[Muse-Inc]

Great article Dori, thanks for posting the link! Explains the APAP algorithm differences nicely and let's us read how each of these mfg presents 'their' APAP.

[ozij]

Thanks, Dori!

Sandman, and S8 units all increased pressure above 10 cm H2O, suggesting a pressure response to other nonapneic events present in the signal. The intelliPAP (DeVilbiss) unit responded less quickly, achieving a maximum therapy pressure of 5.5 cm H2O by the end of the 30-minute apnea session.

The reason for the DeVilbiss's lack of response is that - ironically - the apnea signal selected by the researchers is one of close to 100% reduction in flow, which happens to fall withing the DeVilbiss's "oh my gosh, this is a central apnea, I'm not responding to that" category.

I know this, because in their previous reports, the authors showed the signals.
The breathing pattern thrown at the machines can be seen here "Created Unequal" McCoy and Eiken 2006 - a previous version of the benchmarks, but the breathing patterns were not changed:





This actually the first such benchmark comparison in which the authors take into a account a point made by -SWS years ago: The mahcines in this simulation are not getting any response from the mechanical device connected to them. And this is the first time (IIRC) that the results are analysed withing this proper context.

Science is finally catching up with members of this forum...

[KatieW]

Thanks Dori, I am printing it so I can read it. Only a few months ago, I knew nothing about sleep apnea, and now I'm fascinated by articles like this one.

[rested gal]

Thanks for posting the link to that article, Dori.

Two of the authors, Robert McCoy, RRT; Todd Eiken, RPSGT, do seem to like to "bench test" autopaps and write at length about the "results."

Before anyone gets tooooo impressed by the "COMPARATIVE BENCH TESTING OF FIVE APAP DEVICES" section of that article, please read what one of our cpaptalk members ( -SWS ) has written about the value (or lack thereof) of that kind of artificial comparative testing -- with the machines getting no feedback from live persons.

Topics discussing APAP comparison studies that use an artificial breathing machine:

In several of the topics, take special note of -SWS's criticism of any study purporting to "compare" autopap responses to recorded waveforms generated by an artificial breathing machine. Meaningless when there is no live "patient" in the loop to provide feedback to the autopap.
-SWS understands the workings of all these machines the best of anyone on the forum, imho...and better than most doctors understand them.

Mar 05, 2005 subject: Finally slept through the whole night (topic started by day for night)
viewtopic.php?t=1715
Within that topic:
viewtopic.php?p=11889#p11889 (post by Mikesus)
viewtopic.php?p=11894#p11894 (-SWS points out the flawed design of a study trying to compare APAPs while using an artificial breathing machine.)
New link to the Bliss- Eiken paper (Mikesus's link was broken):
http://www.resmed.com/en-us/dealers/med ... hite-paper. pdf (this forum won't let me post a message with a URL to a PDF in it... but even if you take out the space I put in, the link won't go to the pdf.

But you can get to it this way:
http://www.resmed.com/us
Click: "clinicians"
Click: "research"
Click: "Farrell's Favorites"
then scroll wayyyyy down to this one:
Bliss P, Eiken T, McCoy R. Performance of auto-adjust nasal CPAP devices in a simulation of varied breathing. (white paper, 2003)
_______________________________________

Topic started in Feb. 2005 by a Guest: How AutoPAP works
viewtopic.php?p=7275#p7275

Many links in the posts are broken now. A few statements had been copied:
viewtopic.php?p=7275#p7275
(I quote a self serving question by ResMed's then CEO Peter Farrell to get Sleep Review to name the machines used in the Bliss - Eiken "comparison study.")

_______________________________________

Jan 15, 2007 subject: An APAP Shootout (sort of) on Academic Journal (topic started by SamCurt)
viewtopic.php?t=16570

Within that topic:
viewtopic.php?p=140004#p140004 (my post criticizing the "artificial breathing machine" APAP comparisons.)
viewtopic.php?p=140063#p140063 (-SWS talks about "broken patient feedback loop.")

___________________________

Jan. 25, 2008 subject: Will you listen to sleep techs.., that do not know........?
Topic started by mckooi:
viewtopic.php?t=27954

Within that topic:
viewtopic.php?p=240936#p240936 (my post about not getting hopes up about "comparison" tests of autopaps having any useful meaning.)
viewtopic.php?p=120965#p120965 (in my reply to snoregirl):
But more to the point of your surmise, I agree that resmed is probably aggressively courting the doctors. If they can convince doctors to specify "that company's name" on the Rx....

I wouldn't be surprised if one of resmed's most effective (and misleading) tactics with doctors might be to pull out a fancy chart or two based on those #@$% artificial breathing machine "studies." Even smart doctors might be impressed by those artificial tests, not fully realizing how utterly meaningless they are when feedback breathing from a live human is not in the loop.
________________________________

Later, in an interview with Sleep Magazine, a ResMed representative was bragging about the AutoSet's performance in "APAP comparison bench studies."
That interview is no longer available in Sleep Magazine's online issues.

________________________________


Farre, Montserrat, et al, comparison study (2002):


Response of automatic continuous positive airway pressure devices to different sleep breathing patterns: a bench study.

Farré R, Montserrat JM, Rigau J, Trepat X, Pinto P, Navajas D.


Abstract:

http://www.ncbi.nlm.nih.gov/pubmed/1218 ... t=Abstract


Full version:

http://ajrccm.atsjournals.org/cgi/conte ... /166/4/469

[Muse-Inc]

Thanks RG! So nice you present certain caveats to these articles for those of us still self-educating 'cause we need all the help we can get

[kteague]

You're right on 3 counts, Dori. Yes it was interesting, yes it was long, and yes my eyes glazed over.

I just erased a real long commentary because my eyes were glazing over again, and If I've lost interest in my own ramblings, surely others will too. So I'll just leave it at I'm sure the info on the timing and effectiveness of an apap not set to start at 4 would not be as scary as quoted in the article. My heart goes out to those who think they are protected and are using an apap set wide open.

Thanks for the read.

Kathy

[cinco777]

Thanks for posting the article. I printed a copy and highlighted the most interesting info. My copy is now covered with light blue streaks. I was disappointed that the included charts had such low resolution (272 x 200 or 272 x 180) that they didn't permit a closer study and comparison of the graphs of the five machines.

It was refreshing for the authors to be so blunt in their conclusions such as the paragraph that started with "APAP devices are considered a commodity by many clinicians" and ended with "Unlikely!"

This article reinforces my belief that the knowledgeable and experienced members of this forum, after receiving and analyzing detailed information from a user, will collectively provide a more beneficial machine recommendation than a clinician. Most Sleep Drs, DMEs, and clinicians limit our machine choice to their preferred brand whereas here on CPAPTalk, all available brands compete based on outcomes not just features, reputations, and marketing hype.

[rested gal]

Well, pooh. My "But you can get to it this way" steps won't open the PDF at ResMed's site either.

Maybe it takes being a DME who has a password to get to it nowadays... oh well.

[ozij]

This paper is better that the older ones -- I actually think these benchmark result over the years forced the compaies to reveal their algorithms. The researchers were complaining bitterly about not having that info.

This actually the first such benchmark comparison in which the authors take into a account a point made by -SWS years ago: The mahcines in this simulation are not getting any response from the mechanical device connected to them. And this is the first time (IIRC) that the results are analysed withing this proper context.

Science is finally catching up with members of this forum...

Farrell's Favorites (I knew I saw them recently!)
http://www.resmed.com/int/clinicians/re ... nc=dealers

[cinco777]

I waded through the links that Rested Gal posted. The end result of these earlier "How to test an APAP" discussions among very knowledgeable and experienced members like SWS was that an APAP design needed to be tested using real people with Sleep Disordered Breathing. Period. The mechanical lung breathing simulators just don't have what it takes to simulate a real live person with SDB. A real live person with SDB responds to stimuli (like a pressure increase) - the mechanical simulators didn't and still don't.

Guess what? The members of this CPAPTalk community do real live APAP testing every day, week, month, and year. They test all the different APAP brand machines and then post their detailed graphs, numbers, experiences, comments, critiques, successes, questions, etc. for others to review. They often request help in interpreting their sleep data. We learn from these member experiences and informational exchanges, and this new information helps us make more informed decisions on what will work best for us. The many success stories reported on this forum are a testament to how successful this process is working.

[Curious2]

Very interesting article. I wish, though, the researchers had drilled into the recording and reporting capabilities of the machines--the only significant advantage of APAPs, as far as I am concerned. I long ago came to the conclusion that, for me, at least, a fixed pressure (or very small range, presently set to 10-12) worked best. I suspect one of the reasons I manage best without pressure variation is that way I experience fewer mask leaks, which were once a serious issue for me.

(I use the P-B Silverlining software with the 418p, 420e and 420s. With the 418p and 420e, which are both APAPs, it records detailed information. Some nights, I also use a recording oximeter, to make sure O2 and pulse are ok.)

[ozij]

Siverlining is great.
You can view results by date
You can view resutlts by settings
You can view the per session.
For the 420e you can export 24 hour periods to excel, and you can also export sessions.

I've tried Respironics' software, DeVilbiss's software, ResMed's software. None has the versatility of Silverlining.
ResMed let's you drill down to 10 second periods -- but you can't (well, I couldn't...) focus on the results for a specific setting, nor can you focus on session details.


O.

[Wulfman]

Thanks for posting the link to that article, Dori.

I don't have much to add to what's already been said......just reiterating that it's good from the standpoint of pointing out to those who may prescribe these machines that there ARE differences in the way they function......of course that depends on whether any of the people who prescribe them ever read the article.

Den

[rested gal]

Farrell's Favorites (I knew I saw them recently!)
http://www.resmed.com/int/clinicians/re ... nc=dealers

I went there just now, but don't see a link associated with:
Bliss P, Eiken T, McCoy R. Performance of auto-adjust nasal CPAP devices in a simulation of varied breathing. (white paper, 2003)

There was a link there last night, but clicking it just took a person back to the homepage.

Oh well.