Will you listen to sleep techs.., that do not know........?

[mindy]

I listen very little to what sleep doctors and techs have to say on these boards, for the most part they tell you a whole lotta NOTHING, just like a horoscope, the information is pretty much worthless in helping you resolve anything.

Usually they only stop by here to grab attention and peddle their books. There are always going to be the gullible to take the information they provide hook, line & sinker.

But when was the last time you seen:

a sleep doctor at your PSG?
a sleep doctor go over your PSG the next morning after your study?
a sleep tech going over your study data explaining what was seen?

or that you can

tell your sleep doc and the sleep lab you think you need to be titrated for UARS?

Not a doc
Not a sleep tech (don't work in sleep medicine)
Never wrote a book and don't plan to
Just a simple xPAP user

no sleep doc at my PSG
sleep doc did go over PSG in the am and later discussed other questions on phone
sleep techs not allowed to go over study data
have no idea if I could tell my sleep doc that I need to be titrated for UARS - never asked.



Mindy

[rested gal]

Hi Mindy,

Can you please show me the comparisions of the 7 machines.
Thank you.

Mckooi

I'd strongly suggest reading -SWS's comments (I agreed with him) in the topics linked below, before getting your hopes up that bench tests using artificial breathing machines instead of live patients can yield any valid comparisons between autopaps.

Jan 15, 2007 subject: An APAP Shootout (sort of) on Academic Journal Take special note of -SWS's posts starting on page 2.
viewtopic.php?t=1715


Mar 05, 2005 subject: Finally slept through the whole night.... A twelve page thread!!
viewtopic.php?t=16570

[mindy]

Some of the papers I've read have found no significant differences between CPAP and APAP in terms of compliance. In at least one study, there was an age effect ... older patients were generally more compliant than younger patients whether using CPAP or APAP.

The conclusion of the abstract below may interest Snoredog re his UARS comment. I agree these are artificial breathing machines and not live patients .... however, IMHO, they do provide a basis for evaluating the differences in the various technologies and in a more consistent manner than studies using people. The same way that "phantoms" are used to calibrate imaging equipment. When it comes to equipment, there need to be ways to objectively measure the performance other than using people.

"Bench Model To Simulate Upper Airway Obstruction for Analyzing Automatic Continuous Positive Airway Pressure Devices
Chest - Volume 130, Issue 2 (August 2006) - Copyright © 2006 The American College of Chest Physicians


Jordi Rigau PhD 1
Josep M. Montserrat MD 2
Holger Wöhrle MD 4
Diana Plattner MS 1
Matthias Schwaibold MS 1
Daniel Navajas PhD 3
Ramon Farré PhD 3
1 Science and Research, Measure, Check & Control GmbH & Co. KG, Karlsruhe, Germany;
2 Pneumologia, Hospital Clínic
3 and Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Institut d’Investigacions
Biomèdiques August Pi i Sunyer, Barcelona, Spain;
4 and Department of Internal Medicine II (Dr. Wöhrle), University Hospital, Ulm, Germany.

Background: Automatic positive airway pressure (APAP) devices are increasingly being used in patients with obstructive sleep apnea. Some APAP devices present an unstable behavior when subjected to some events or artifacts. The aims were to develop a bench model capable of reproducing real flow, snoring, and obstructive patterns and to compare
the response of APAP devices based on flow and snoring with other devices using, in addition, the forced oscillation technique (FOT).

Methods:The bench model subjected APAP devices to apneas with and without obstruction, obstructive hypopneas with and without snoring, periods of flow limitation, and artifacts such as leaks and mouth expiration.

Results: Almost all the devices increased the pressure when subjected to apneas with obstruction, but at different rates. The time required by each device to reach 10 cm H2O ranged from 2.5 to 13 min. In the presence of apneas without obstruction, all the devices based on flow and snoring increased the pressure at the same rate as during apneas with
obstruction. However, the devices using FOT did not modify the pressure. Four devices did not modify the pressure in the presence of obstructive hypopneas, and all but one device increased the pressure in the presence of snoring. Mask leaks had little effect on the response of the devices, but four devices increased the pressure during mouth expiration artifacts.

Conclusions:When, in addition to the flow and snoring signals, the measurement of the upper airway resistance is included, the accuracy of the event detection algorithms is improved."

"...We modified the patient simulator model previously described [33] by including an obstructive valve servocontrolled by a motor (HS-325BB; Hitec RCD; Powey, CA). This new model was able to reproduce not only real flow and snoring signals obtained from patients’ recordings, but also the corresponding resistance of the upper airway...
"
"During mouth expiration, the exhalation valve was opened allowing the expired air to flow through the simulated mouth route while the obstructive valve was closed. A leak valve was used for simulating leaks through the mask usually found during conventional CPAP treatment in patients"...

"A second set of five breathing patterns was used to simulate the behavior of a real patient when subjected to treatment with an APAP device ...These breathing patterns (based on previously described flow patterns [33] ) were complete events recorded in patients. Therefore, they reflect the within cycle variability found in real events (the flow amplitude and shape
progressively changed along the event..."

Machines evaluated include: PV10i, Autoset Spirit, Remstar Auto, Delphinus, Magellan, Goodknight 420E, Horizon LT Plus, Autoset Plus, SOMNOsmart 2 and AutoTREND.

There is a good deal here that I can't reproduce but hopefully the above is enough to give some idea of the thought that went into the design of this study.

m

m

[rested gal]

An excerpt from page 4 of:
viewtopic.php?t=16570

If the researchers testing is flawed I have no doubt that the medical profession and the manufacturers would be able to publish credible data explaining in a credible fashion why the research is invalid or needs refining. It took years for the R-- algorithms to be accepted as representational patterns useful in respiratory research.

I think your missing the point, Doug. Nobody has ever insinuated those R-value waves are unsuitable as standardized input. Standardized input is needed. I take absolutely no issue whatsoever with those well-designed R-value inputs. But that's where the methodology design ceases to be valid as far as I am concerned.

You are speaking as if standardized input and overall testing methodology are one in the same, Doug. You can devise the world's greatest bricks and still build a methodological structure that is not sound. Regarding this methodology with the grotesquely missing patient (or even simulated) feedback loop: just calculate the experiment's residual AHI scores across all machines, and you will see how far that methodology's results deviate from what patients with any of those machines typically attain.

If that methodology is even implicitly aimed at making overall comparative assessments of each machine's efficacy, then it's just plain-old bad methodology. It fails to encompass key design and even sleep-related trend-based operational aspects of each machine's algorithm. It measures one manufacturer's designed non-responsive (NR) algorithmic routine, then depicts that somewhat esoteric designed response as if it were a comparative failure. Yes, that's one highly flawed methodology toward overall comparison. It's a series of unfortunate and highly misleading "micro measurements" in my honest and completely unbiased opinion.

[rested gal]

An excerpt from page 6 of
viewtopic.php?t=16570

I mean, if the waveform analysis and event response of these machines is fixed, then sending in fixed signals for machine comparison is an absolutely valid methodology to analyze those characteristics. Waveform analysis really isn't that hard to do, and the major differences between machines will occur in the definition of what a flow limitation is and what the response algorithms are.

In my opinion it's valid methodology regarding only event detection itself (and then with some very major black-box qualifying/disqualifying considerations that I won't get into here). However, I don't think the approach is valid or accurate regarding either the end-to-end analysis of any APAP system or the overall efficacy of any one or group of APAP machines. And if this is not a suitable methodology for either of those two purposes, then what purpose does that methodology serve other than declaring a serious need for disclosure by manufacturers? Doug brought up the entirely valid point much earlier in this thread that this methodology also serves to make a dent in the overall problem of devising suitable efficacy related bench-testing.

But getting on to the low-level specifics once again... The biggest problem I have with this methodology as a benchmarking tool toward making overall efficacy comparisons, is that the methodology involves only flow-limitation detection and short-term algorithmic response. The methodology cannot and does not factor in certain key algorithmic-crucial events that are absolutely fundamental to the overall software architecture of any APAP system design.

As an example, snore detection is used on an entirely prophylactic basis for all the APAP algorithms sitting on that test bench. However, the testing methodology currently up for discussion does not even attempt to factor in this key prophylactic breathing signal. The methodology itself neglects what is perhaps the most important patient-based input signal. If any system's key input signal(s) are methodologically neglected, the system's design becomes inadvertently subverted, and the system's output is virtually guaranteed to become skewed. And that's exactly what happened with these system-output-oriented test results. But this is only one example of why breaking the crucial patient-to-machine feedback loop renders a methodology inadequate toward either assessing end-to-end system design or toward making overall APAP efficacy comparisons.

The methodology up for discussion also fails to factor in several other patient-based key inputs. Another example that comes to mind would be the experimental pressure-deltas that some algorithms introduce. The Respironics algorithm, for example, will occasionally drop then raise delivered pressure to gauge patient response (another missing patient-based input here) toward prophylactically calculating a new optimum therapeutic pressure. Conversely the PB algorithm will occasionally raise then drop pressure toward making similar prophylactic calculations under certain IFL configurations. Again, this bench-testing methodology cannot yield results suitable toward assessing any of these systems' designed outputs because that crucial patient-to-machine feedback loop has been broken.

[mindy]

An excerpt from page 6 of
viewtopic.php?t=16570

As an example, snore detection is used on an entirely prophylactic basis for all the APAP algorithms sitting on that test bench. However, the testing methodology currently up for discussion does not even attempt to factor in this key prophylactic breathing signal. The methodology itself neglects what is perhaps the most important patient-based input signal. If any system's key input signal(s) are methodologically neglected, the system's design becomes inadvertently subverted, and the system's output is virtually guaranteed to become skewed. And that's exactly what happened with these system-output-oriented test results. But this is only one example of why breaking the crucial patient-to-machine feedback loop renders a methodology inadequate toward either assessing end-to-end system design or toward making overall APAP efficacy comparisons.

I don't think this is the same study referred to earlier. Note that the paper I quoted *does* include snores in it's methodology and part of the testing included recorded sleep data as input to the device. I expect that this more recent paper uses an improved methodology to simulate sleep apnea to test APAPs.

There are benefits and drawbacks to both bench testing and human testing. It often requires both to provide really good data.

m

[Guest]

Hi Rested Gal and All,

After reading thru all the posted messages fom SWS, I agreed with him absolutely. In relation to the simulation test it was obiously was not tested on the 1) new model like repsronics m-series auto-pap, 2) At what pressures shoudl be tested 3) besidea teh mask issues...leaking 4)Adhenrence of all the startight cpap users that dropped out various reasons etc...It seems as the sleep docs, sleep techs, researchsers all need to re-certify timely basis on their knowledge bside need to fully understand the hardware, software algorithms for al lthe subsets of OSA patience carefully, instead of 1 big yard stick hammer all in one manner to alteh osa sufferes and this is a very serious issues...for exmaple I remebered taht in Norzy case....was in the wrong track for years due to sleep doc lask ofknowledge and wroongful recomendationd and hence wrong teratment and conseqeunces were at very high price....in fact too sad to be mentioned.

Mckooi

[rested gal]

Mindy, you're right that the old topics did deal with several past bench test studies. I think the study you're talking about was discussed in some of them, however.

As for what -SWS said about the bench test that didn't take snore detection into account, he went on to say....

But this is only one example of why breaking the crucial patient-to-machine feedback loop renders a methodology inadequate toward either assessing end-to-end system design or toward making overall APAP efficacy comparisons.

(bold emphasis mine.)

When autopaps are not receiving feedback from a live person at the other end of the hose, they are not...they cannot...perform the way they are designed to work. Even if the waveforms lobbed at the autopap have been recorded from real people, the autopap is still not receiving feedback in response to whatever action the autopap has just done. To whatever action it did (or did not) take.

Without feedback response from a live person, all the autopap can do is .... whatever it does when faced with a recording that simply plays on, oblivious to what the autopap did/did not do.

Doesn't matter how simple or complicated the recorded waveform(s) are.

Doesn't matter if they were recorded from real sleep disordered breathing people in a sleep lab.

What matters is that there is still not a live person giving that all-important feedback to the auto, in response to what the auto does/doesn't do, so that the autopap can "decide" what to do next.

That, to me, is what will always keep bench tests that use a programmed artificial breathing machine in lieu of a live person from yielding any truly meaningful comparison between brands of machines. Or even showing much, if anything, about what each machine would actually do if a live person were breathing back at it.

Unfortunately, such bench tests are apt to lead people (doctors, even! LOL ) to wrong conclusions about how this, that, or the other autopap would or would not actually behave with a live breathing human at the other end.

[mindy]

What matters is that there is still not a live person giving that all-important feedback to the auto, in response to what the auto does/doesn't do, so that the autopap can "decide" what to do next.

That, to me, is what will always keep bench tests that use a programmed artificial breathing machine in lieu of a live person from yielding any truly meaningful comparison between brands of machines. Or even showing much, if anything, about what each machine would actually do if a live person were breathing back at it.

RG,

I agree with that! What I think they accomplish is to provide a predictable way of determining how these machines work. I do not think that the comparisons of bench tests should be used to compare one machine Vs. another in terms of which one to use. That seems to be so highly individual that today there doesn't appear to yet be a good way to determine that except trial and error. I do believe that researchers are attempting to head in that direction.

I see bench tests primarily as a stepping stone in the quest to be able to match machine and parameters to the person and I'm grateful that there are folks working on it. It may be slightly analagous to using cadavers to test certain devices that can affect skeletal range of motion. Ultimately it has to be tried in real people before really useful conclusions can be drawn.

When I read a sentence like the following by SWS ("It's a series of unfortunate and highly misleading "micro measurements" in my honest and completely unbiased opinion. " my antennae go straight up. I'm sure it was an honest opinion and it may well be 100% correct (I certainly don't know enough to refute that) but I find it disturbing for anyone to claim that their opinion is "completely unbiased". We all have built-in biases no matter what. I realize that it's far too easy for any of us (myself definitely included) to come off sounding like we think we know it all ... I sometimes forget to add those crucial disclaimers that something is important or interesting or whatever "in my opinion" or "here's something I've read that I think is thought-provoking".

I do think we're a good ways from the ideal of being able to match person and the "right" machine without trial and error. Perhaps someday there will be a machine that will match itself to each person

Thanks for your thoughtful insights, RG. You keep me on my toes!

Mindy

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): auto

[rested gal]

Mindy, it helps that I've known -SWS for a number of years, through several message boards as well as having met him and his wife "in real life." I've never known anyone who can do a better job of putting aside any biases he might have (I haven't seen any, but he is a human...lol) when it comes to thinking about technical matters.

Spiced (or spliced...however one looks at little blowups) into some of the old threads are the inevitable side issues that crop up when people take umbrage at what others have said, or how they said it. Not to speak for -SWS, but I think he was emphasizing that he was looking at the bench study in a completely unbiased manner because others in that thread had raised the issue of a perceived "bias" toward Respironics machines on this message board:

And I do have to say that I am of the opinion that had this report said that the Respironics Auto was the best or had no issues, there would be none of this debate.

That fellow eventually edited out his comment, but it had already been noted and quoted by several others in the thread.

Anywayyyy... it was stuff like that which probably prompted -SWS to make clear that he was looking critically at the methodology of the bench test itself...not because of how one brand or another "performed" in it.

The man is a rigorous and brilliant scientific thinker, as well as one of the most compassionate people I've ever met. If anyone is capable of honestly setting aside any biases they might have in order to look at something scientifically from all sides as well as outside the box... he can do that.

Does my biased opinion of -SWS show?

[mindy]

Does my biased opinion of -SWS show?

Yep!

And I appreciate your putting the matter in the appropriate context. I know there are some incredibly sharp people on this forum and they enrich all of us with their knowledge and opinions. Based on what I've seen of your posts, I would certainly accept your opinion of -SWS-. It is certainly easy to miss some of the finer details.

I've had the great fortune to work with some amazingly brilliant people and the experience has been so stimulating.

Thanks!
Mindy

[Guest]

Hi Rested Gal,

It was a brillaint input from your recollection of valueable knowledge via all the brillaint brains from this forum of sws etc (sometimes i wondered why you have such a great memory? having said that one of my biggest challenge is to remember things....1. could it be the impact of years of OSA?) I kudo to you in many way...2.any help on memory capacity are welcome. On another matter on the auto-pap setting...3.why the manual from the auto-pap not event mentioned of how to set the proper pressures or at least and important strategic point of setting the min and max pressure etc. If the the docs/sleep techs/researchser ... relauctant or not welling to pass the knowledge I would be very concern.....$$$$$ wont frlow into their banks? Base on the these questions, what is the potential strategic to set the pressures on the auto-pap, straight cpap and best practices? I think of these main issues outline as simple guidance would be able to help many to understand the underlining of the treatment. Any comments are welcome?

1) Strategic approaches of pressure setting.
2) Best Parctices.
3) Adhencrences.
4) Any orthers to add?

Mckooi

[Snoredog]

I listen very little to what sleep doctors and techs have to say on these boards, for the most part they tell you a whole lotta NOTHING, just like a horoscope, the information is pretty much worthless in helping you resolve anything.

Usually they only stop by here to grab attention and peddle their books. There are always going to be the gullible to take the information they provide hook, line & sinker.

But when was the last time you seen:

a sleep doctor at your PSG?
a sleep doctor go over your PSG the next morning after your study?
a sleep tech going over your study data explaining what was seen?

or that you can

tell your sleep doc and the sleep lab you think you need to be titrated for UARS?

Not a doc
Not a sleep tech (don't work in sleep medicine)
Never wrote a book and don't plan to
Just a simple xPAP user

no sleep doc at my PSG
sleep doc did go over PSG in the am and later discussed other questions on phone
sleep techs not allowed to go over study data
have no idea if I could tell my sleep doc that I need to be titrated for UARS - never asked.



Mindy

I was responding to the subject title of this thread with my reasons why I don't believe everything I read and from suggestions made in another thread.

For example,

Someone recently sent me a link to the APAP vs CPAP for Cardiovascular benefit comparison from Chest published back in May 2007, I had already seen the study and I think we discussed it here back when that study first came out.

They wanted me to comment on it, personally, I find those studies worthless as tits on a boar (like my opinion means anything to anyone) but you guessed it the results of that study the autopap lost just as I expected it would.

But when you think about it, who does studies on efficacy of Autopaps?

Doctors and sleep labs right?

Who has a direct financial interest in the outcome of these studies? you guessed it,
Doctors & Sleep Labs.

Can we expect to see a study showing us where the autopap actually does better than CPAP like with compliance? Not on your life!!

Why is that?

Well if they (doctors and sleep labs) performed a study showing positive results from an autopap that study would NEVER get published. Afterall, they are not going to shoot themselves in the wallet publishing a study.

But the fact remains we have seen it happen here over and over, get an autopap and take over your own therapy and you don't need either one as often, that eventually hurts their pocketbook.

Remember those studies are performed by doctors and sleep labs, that is like hiring the big bad wolf to babysit little red riding hood.

Then there were studies done on Vioxx and most recently Vytorin wasn't there? Then another showing Zoloft didn't work either. Who performed those studies?
Hey they were FDA approved. As patients, aren't we led to believe that when a prescription drug becomes available that it has undergone scientific testing for efficacy and adverse side effects yet every year we find after the fact none of what we were previously told was true.

So it appears having study results and FDA approval doesn't mean didly squat. And I don't buy that hogwash you cannot self-titrate yourself with a Bipap and buy my book to find out more, that is simply more of the same hype we've seen here before and another one just protecting his/her cash cow.

[ozij]

As a matter of fact, that research showed that sending a person out for 3 months on wide open 4-15 range is not a good idea for people who have a heart condition.

And, since using a wide open range is becoming gradually more popular, that is important info.

O.

[mindy]

I have seen recent studies showing the better compliance with APAP and the fact that it may well be less expensive to use APAPs since it would reduce the number of sleep studies needed.

In some of the classes I've taken, it was clear that how much credence to put in studies depends on many factors. Among them: independent funding (e.g. not Big Pharma nor device manufacturers). It's why government funding from sources like the NIH is so crucial. If that's not available and foundation money is not available, then the main sources are the manufacturers (fox guarding the henhouse!). In addition to funding source, we also look for various other things to try to determine if a study is likely to be valid. Among them are 1) an evaluation of the methods and potential flaws, 2) reputation of the researchers, 3) reputation of the journal, 4) knowledge of the subject matter.

Good peer-reviewed journals have anonymous reviewers with substantial knowledge of a subject area review in depth those papers that even pass the first check. They often question anything and everything. The reviews (often 2-3) and the editor's comments sometimes run many pages. If the questions aren't answered satisfactorily, the paper isn't published. So what I'm trying to say is that yes, I wouldn't be surprised if poor research gets through but if we take care in selecting both journals and read papers critically, we can obtain some good information.

Because I have a heart condition, I discussed with my sleep doc the issues about APAP Vs. CPAP. My doc said that it was a huge topic among sleep docs and that (as I've read) there are no definitive answers as of yet. There has certainly been a real recognition in the literature that APAP provides better relief and can be an important factor in compliance. It's frustrating but it generally takes multiple studies to really prove or disprovev a hypothesis properly.

I don't work at the level of all of the details of shape of the air flow, etc. etc. I do browse the literature and try to keep up on what's happening and I have a fairly decent working knowledge of medical research. It's like anything else - there are some really top-notch researchers doing great work and there are some that are a little less rigorous. It's up to the reader to decide which in their own opinion. When the weight of the evidence is strong enough, change hopefully happens.

The whole area of new drugs is a completely different ballgame, IMHO.

Mindy