An APAP Shootout (sort of) on Academic Journal

-SWS wrote:

SAG wrote:So the question is, why aren't all the OSA patients on jet ventilators instead of CPAP machines?

Dunno! The question itself may go toward the immense number of factors that can make or break any given medical technology in the market place. And if a new or alternative technology does happen to make it to the market place, the duration of time required for that product to go through the research cycle, followed by a necessary development cycle, and finally onto a product-release date can alter radically on a product-by-product basis. However, one of many possible circumstances affecting a new product's release date (or whether the candidate technology is even pursued) is precisely what competing products, competing technologies, and even established in-house alternatives happen to be up to in the marketplace.

At least that is my initial thought as an outsider to the industry of sleep science itself. However, what do SAG and others here think regarding why patients may not be presently using pressure-oscillation treatment techniques? Is this perhaps another case of medically or financially unfeasible technology? Or is this a potentially viable technology that simply has yet to make it through the scientific and corporate gauntlets (that can be both unique and highly circumstance driven)?

As an avid researcher of medical research itself, our SAG just may have the answer for us! But in modern sleep science there are undoubtedly many more questions than answers. Talk about a challenging field...

Great observation, Doug. The original FOT-based Somnosmart came out several years ago. SAG's rhetorical question essentially restated with corporations in mind: "Why, then, aren't the other manufacturers jumping on the FOT bandwagon?" I would also note that product research, development, and roll-out decisions happen independently within each company. Corporations tend to make highly independent decisions, although they are also compelled by the same forces within their vertical market. Sometimes absolutely viable technologies fail to be universally deployed in the marketplace, especially when/if competing companies perceive that those competing technologies serve no clear revenue advantages over current product offerings.

Aside from the above business-oriented observations, there may have been at least some FOT efficacy shortcomings in the very first Somnosmart production model. If I recall correctly (this is not a safe bet unfortunately), I thought the original Somnosmart exclusively employed FOT detection---and that the current Somnosmart 2 now additionally employs traditional flow-based sensors common to traditional APAPs. If my recollection above is correct, then the other manufacturers may not even perceive FOT as being adequately compelling.

on edit: Doug, or anyone-- if you get a chance would you mind taking a peek at Somnosmart 2, to see if it does happen to include flow detection as well as FOT? Otherwise I'll check after vacation. I really need to get out of this thread for a few weeks, but it's way too interesting. Gotta go cold turkey with this thread for at least a while... I will have time in the next two or three days to lurk, though! .

SWS,

Agree - unless FOT was something of a revolutionary breakthrough (like: Cpap, Bipap, Auto, BipaAuto, Adaptive Servo), then it really is a high risk deviation & could leave the company using it somewhat isolated, but I guess some newcomers into this field could feel it worth the risks.

I wouldn't buy one just for the heck of it

DSM

I suppose there's a lot of reasons why products don't get to market, but ya gotta think the obvious.

A couple years after the dogs, another study came out, and the point was clear in the title:

Forced Oscillation Measurements Do Not Affect Upper Airway Muscle
Tone or Sleep in Clinical Studies

This group showed that

In this study, high-frequency oscillation did not result in any increase in EMGgg activity or promote resolution of upper airway obstruction. Frequency analysis of the EEG signal was carried out and no evidence of neurological activation was found. These findings are consistent with the clinical experience with FOT. Significant effects on the upper airway or the EEG produced by the use of FOT, with and without CPAP, were not observed in subjects with SAHS....This lack of effect of forced oscillation on upper airway muscle activity can be considered, to some extent, as contradictory to results from other groups. Most of these previous studies were carried out in chronically tracheostomized dogs. These experimental conditions are very different from clinical sleep studies in the human. However, Hencke and Sullivan have shown evidence of EMG activation in the sleeping human, both in healthy subjects and in patients with obstructive sleep apnoea. The presence of arousal or microarousals leading directly to upper airway muscle activation could be a possible explanation for these divergent results. In this study, trials that promoted immediate arousal were discarded, but trials in which arousal occurred shortly after stimulation were included in the analysis.

In other words, you can also generate arousal and subsequent EMG activity by standing behind a sleeping subject with a metal pot and wooden spoon.

Keeping in mind that it's the Barcelona group that appeared to be pushing the Somnosmart, what makes this article even more interesting is the authors of this study:

J.R. Badia, R. Farre´, J. Rigau, M.E. Uribe, D. Navajas, J.M. Montserrat

Buenas margaritas, is that a hoot or what?
SAG

StillAnotherGuest wrote:I suppose there's a lot of reasons why products don't get to market, but ya gotta think the obvious.

I'm a big fan of obvious. Vested interest can actually influence claims both ways.

In summary, we have shown that when the upper airway is briefly subjected to a pressure wave of 30 Hz with an amplitude of 4 cmH,O, there is an increase in the activity of some muscles of the upper airway. This occurred in normal subjects and in patients with a range of obstructive sleep apnea. In the latter, the response of the upper airway muscles can be sufficient to open the obstructed upper airway. The occurrence of similar responses in the sternomastoid and diaphragm suggests that a number of receptors are activated by the stimulus. It is possible that these responses could be utilized in developing new treatments for sleep apnea.

Speaking of obvious... Did you per chance notice that second refuting study applied only 1cm of FOT amplitude? Recall the FOT study in the quote above called for 4cm of FOT amplitude. The original study really called for 400% more FOT pressure than the refuting study used.

So where is the vested interest here? I can't conclude if it's in the original study, the pots and pans claim, or neither (second refuting study seems to refute only what they term "lower" pressure claims, at 1cm). Could be yet other undisclosed or unforeseen factors at play in either the 1cm or 4cm studies as well. I personally dunno about 4cm FOT without yet more independently verified studies that target the same treatment amplitude. So SAG, what other 4cm FOT studies do you have without the kitchenware or the kitchenware claims? Thanks for posting them all. So much for cold turkey on my part.

StillAnotherGuest wrote:I suppose there's a lot of reasons why products don't get to market, but ya gotta think the obvious.

A couple years after the dogs, another study came out, and the point was clear in the title:

Forced Oscillation Measurements Do Not Affect Upper Airway Muscle
Tone or Sleep in Clinical Studies

This group showed that

In this study, high-frequency oscillation did not result in any increase in EMGgg activity or promote resolution of upper airway obstruction. Frequency analysis of the EEG signal was carried out and no evidence of neurological activation was found. These findings are consistent with the clinical experience with FOT. Significant effects on the upper airway or the EEG produced by the use of FOT, with and without CPAP, were not observed in subjects with SAHS....This lack of effect of forced oscillation on upper airway muscle activity can be considered, to some extent, as contradictory to results from other groups. Most of these previous studies were carried out in chronically tracheostomized dogs. These experimental conditions are very different from clinical sleep studies in the human. However, Hencke and Sullivan have shown evidence of EMG activation in the sleeping human, both in healthy subjects and in patients with obstructive sleep apnoea. The presence of arousal or microarousals leading directly to upper airway muscle activation could be a possible explanation for these divergent results. In this study, trials that promoted immediate arousal were discarded, but trials in which arousal occurred shortly after stimulation were included in the analysis.

In other words, you can also generate arousal and subsequent EMG activity by standing behind a sleeping subject with a metal pot and wooden spoon.

Keeping in mind that it's the Barcelona group that appeared to be pushing the Somnosmart, what makes this article even more interesting is the authors of this study:

J.R. Badia, R. Farre´, J. Rigau, M.E. Uribe, D. Navajas, J.M. Montserrat

Buenas margaritas, is that a hoot or what?
SAG

I read SAG's implications simply as: the original 4cm FOT study is a manufacturer-related study, so buyer beware. However, SAG also points out that sensory-based arousals are thought to be the true cause of airway reaction in that second study. He thus implicitly associates that as a possible factor in the first study as well (correctly so in my opinion).

My summarized thoughts relative to SAG's above points are that: 1) sensory-based arousals just may have been better/worse controlled in either study, and that 2) there is potentially a significant therapeutic difference between FOT at only 1cm versus FOT at 4cm.

Doug, my own comment was the one that threw you. I don't think SAG implied the second study had such a great potential for vested interest. However, I said vested interest can work both ways. And that was really nothing more than a generalization on my own part. I cannot discern that there is or is not vested interest on anyone's part here. Only that it happens from time to time. And I thus agree about SAG's caveat emptor implications as a valid but general consideration.

I went to the Weinmann.de german website, selected the Somnosmart machine, then downloaded the Scientific Publications that SAG mentions, I like to read them a couple times but so far I see the FOT in the Somnosmart machine superior. I read it to use "peak" impedance. If you read the entire test (not just the abstract) you see that the Somnosmart avoided responding to central events where the other machines didn't including the AutoSet.

We have to remember if you are a autopap manufacturer coming in late in the game you have to dance around a lot of existing patents to come up with your own algorithm. Who knows, maybe they came up with something better. I wouldn't mind trying one of their autopaps they look pretty good from what I've read and they are about 4dB quieter than the nearest competitor.

Anonymous wrote:I went to the Weinmann.de german website, selected the Somnosmart machine, then downloaded the Scientific Publications that SAG mentions, I like to read them a couple times but so far I see the FOT in the Somnosmart machine superior. I read it to use "peak" impedance. If you read the entire test (not just the abstract) you see that the Somnosmart avoided responding to central events where the other machines didn't including the AutoSet.

We have to remember if you are a autopap manufacturer coming in late in the game you have to dance around a lot of existing patents to come up with your own algorithm. Who knows, maybe they came up with something better. I wouldn't mind trying one of their autopaps they look pretty good from what I've read and they are about 4dB quieter than the nearest competitor.

The machine looks promising to me as well. Then, of course, the caveat implied by SAG all along is that manufacturer web sites tend to host studies that are highly flattering to those manufacturers. Strange but true.

-SWS wrote:I read SAG's implications simply as: the original 4cm FOT study is a manufacturer-related study, so buyer beware. However, SAG also points out that sensory-based arousals are thought to be the true cause of airway reaction in that second study. He thus implicitly associates that as a possible factor in the first study as well (correctly so in my opinion).

My summarized thoughts relative to SAG's above points are that: 1) sensory-based arousals just may have been better/worse controlled in either study, and that 2) there is potentially a significant therapeutic difference between FOT at only 1cm versus FOT at 4cm.

Doug, my own comment was the one that threw you. I don't think SAG implied the second study had such a great potential for vested interest. However, I said vested interest can work both ways. And that was really nothing more than a generalization on my own part. I cannot discern that there is or is not vested interest on anyone's part here. Only that it happens from time to time. And I thus agree about SAG's caveat emptor implications as a valid but general consideration.

SWS,

Thanks for that - I can see the point clearer from your clarification.

I can understand the dilemma of any newcomer seeking to break into this market & the more I learn of the technologies, the more I think I understand why each company guards its algorithms & patents so tightly.

I am sure I can see some such battle in regard to monitoring airflow & why Respironics & Resmed appear to use quite different approaches.

The good thing that I see though (IMHO & at this stage), is that there are enough good established and different designs to keep the market healthy & not allow one manufacturer to monopolise it by locking their competitors away from some core technology.

Interesting stuff & again thanks for your clarifications.

DSM

-SWS wrote:

StillAnotherGuest wrote:I suppose there's a lot of reasons why products don't get to market, but ya gotta think the obvious.

I'm a big fan of obvious. Vested interest can actually influence claims both ways.

In summary, we have shown that when the upper airway is briefly subjected to a pressure wave of 30 Hz with an amplitude of 4 cmH,O, there is an increase in the activity of some muscles of the upper airway. This occurred in normal subjects and in patients with a range of obstructive sleep apnea. In the latter, the response of the upper airway muscles can be sufficient to open the obstructed upper airway. The occurrence of similar responses in the sternomastoid and diaphragm suggests that a number of receptors are activated by the stimulus. It is possible that these responses could be utilized in developing new treatments for sleep apnea.

Speaking of obvious... Did you per chance notice that second refuting study applied only 1cm of FOT amplitude? Recall the FOT study in the quote above called for 4cm of FOT amplitude. The original study really called for 400% more FOT pressure than the refuting study used.

No, -SWS, I didn't notice that. And I must apologize, I'm afraid that was a typo that occurred during C&P, the original character was "<1" that was read as a "4" converting the .pdf, I didn't pay attention. All the FOT's look to be <1, a 4 cmH2O wave would be like the warning bumps you hit on the way to the toll booth.

Most observant, it is clear that I need to see the obvious!
SAG

SAG wrote:And I must apologize, I'm afraid that was a typo that occurred during C&P, the original character was "<1" that was read as a "4"

We always appreciate your input, SAG. No apologies are necessary for what I shall forever think of as the "atrocities of OCR". .

To offer a little more background information before we get to the current APAP comparison (the article Bench Model To Simulate Upper Airway Obstruction for Analyzing Automatic Continuous Positive Airway Pressure Devices seems to push Somnosmart2) there are questions that will need to be addressed. Keeping in mind, however, that there is a new Somnosmart, and these comparisons are from a bit ago.

BTW, Mike and Stevie-Paul offered anectdotal comments in one of their patents in re: FOT:

This 'forced oscillation method' requires the ability to modulate the mask pressure at 4 Hz, which increases the cost of the device. Furthermore, the method does not work in the presence of high leak, and can falsely report that the airway is closed if the subject has a high nasal or intrapulmonary resistance.

Yet, did you know that AutoSet II Plus sends an impulse signal of 5Hz? Anybody got one of them?

There was prior work comparing FOT and flow-based algorithms:

Evaluation of Unattended Automated Titration To Determine Therapeutic Continuous Positive Airway Pressure in Patients With Obstructive Sleep Apnea

where the differences between AutoSet and Somnosmart results were discussed. Interesting points brought out included that

The possible causes of these discrepancy in pressures between the Autoset and Somnosmart devices could be related to four possible mechanisms: different algorithms, different signal analyses, patient characteristics, and the possible impact of FOT on upper airway collapsibility...

From the display of the pressure recordings, it ensues that the P95 may have a different signification for each device. Indeed, for the Somnosmart device, the P95 cuts the top of the pressure peaks, underestimating probably the therapeutic pressure. Furthermore, it is possible that the two devices adjust pressure differently in case of nasal obstruction or leaks. Badia et al reported that leaks and mouth expiration, which occur quite frequently during the night, are the main limitation to the use of the FOT. Moreover, an algorithm allowing prompt changes in airway pressure could also generate more sleep fragmentation by increasing arousals or microarousals...

The differences in pressures between the Autoset and the Somnosmart could also be due to different analyses of the signals. For example, in the Autoset device, snoring is derived from the vibration of the flow signal. In the Somnosmart device, snoring is defined as a variation of impedance. That means that when snoring is not accompanied by an increase of impedance, it will not been taken into consideration by the Somnosmart. In other words, only obstructive snoring will lead to increments of the CPAP pressure in the Somnosmart device though obstructive and nonobstructive snoring episodes may have the same consequences with the Autoset device. From this, it could be expected that the P95 would be higher for the Autoset than for the Somnosmart device.

And in another study:

In conclusion, the results of the present study show that a significantly better suppression of snoring is achieved by APAPfl than with APAPfot. Furthermore, AHI was lower with APAPfl than with APAPfot, although this difference was not statistically significant. The pressure profile of AutoSet device was strikingly different from the SOMNOsmart device in that AutoSet device had a higher median pressure but less pressure variability than the SOMNOsmart device. The difference in pressure profile best explains the differences in snoring and AHI observed with these two devices.

Efficacy of Flow- vs Impedance-Guided Autoadjustable Continuous Positive Airway Pressure: A Randomized Cross-over Trial

OK, but no bottom line, at least, not yet, anyway. Machine choice could end up being as individual as mask choice. Certainly in some individuals. Have to peel back a few more layers of the onion.
SAG

SAG,

More great dat - keep it flowing

Also when you say Autoset II what make/model is that ? (I may have one but nothing I have seen uses a name like that ? - I usually associate the word Autoset with Resmed brand, just like I do Bipap with Respironics, but that is because I don't know any better).

#2 Just did a quick google & saw the Farre Monsarrat study that mentioned
Resmed Spirit, then mentioned the Resmed Autoset II PLus (totally new to me).

"Three devices with detection algorithms based on the flow shape and snoring were analyzed: REMstar auto (Respironics, USA), Autoset Spirit (Resmed, Australia), PV10i (Breas, Sweden). Two additional devices, which detect also increases in airway resistance, were analyzed: SOMNOsmart 2 (Weinmann, Germany) and Autoset II Plus (ResMed, Australia)."

This Autoset II Plus device has really slipped in under my radar !


DSM

#3 More research - all resmed models (from their stock exchange data)
http://www.investor.reuters.wallst.com/ ... ticker=RMD

"The VPAP products include VPAP II, COMFORT, VPAP II ST, VPAP II ST A, VPAP MAX, Moritz S, Moritz ST, VPAP III, VPAP III ST, VPAP III STA, VPAP Adapt SV. Ventilation products include Helia 2, Eole 3 XLS, VS Serena, VS Ultra, VS Integra, Elisee 350, Elisee 150, Elisee 370 and Elisee 250. Automatic positive airway pressure devices include AutoSet CS, AutoSet T, AutoSet Spirit, Magellan, AutoSet Respond and AutoSet CS2. the CPAP products include Max II nCPAP, Mini Max nCPAP, Mini Max nCPAP, ResMed S6 series, ResMed S7 series and ResMed S8 Series."

Note there is no mention of an Autoset II PLus but I can find several references to one dating back to 2002 using Google. Like I said - this one is under my radar (note the mention of the Autoset CS2 though )

D

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, resmed, bipap, auto

-SWS wrote:I thought the original Somnosmart exclusively employed FOT detection---and that the current Somnosmart 2 now additionally employs traditional flow-based sensors common to traditional APAPs

And we'll also have to see if it constantly FOTs or only occasionally FOTs. I mean, just about everybody FOTs occasionally, but continuous FOT-ing...(sorry, too much caffeine already).

AHEM!

The only thing I can find out about the ResMed approach to FOT-ing in the above reference is that

The Autoset II Plus (Resmed) generated a small pressure oscillation (5 Hz) when no breathing flow was detected in the course of 8 s. This capability allowed the device to detect obstructions only during apneas.

and I would wonder if generating an impulse in that fashion would be like the "spoon-pot effect" and create an arousal. Or would that be academic, would you have an arousal anyway. But, in the case of CSR, a lot of folks just sleep right through centrals. Or if you're having that many centrals, you shouldn't be on an APAP anyway. But occasional centrals don't create a tear in the universe. And if they're post-arousal, there's REALLY nothing you can do, you don't even count those. Except if they were caused by a burst of FOT...

Hmm, I wonder if there was a point in there.
SAG