APAP Does Not Work As Good as BiPap?

[pratzert]

Hi Everyone....

I just read this information over on another Apnea Forum Board (apneasupport.org) and find it kind of contrary to whit I thought was true.

QUOTE: "By what you have posted, I believe you are using an auto adjusting machine ? There could be a situation whereby all your apnoea events are not being cleared..............this can, and does happen frequently with APAPs. There are a number of posts on the forum concerning this. I might add that a significant number of sleep doctors won't prescribe them for this reason.

Another thing that struck me..........do you have a copy of your original sleep study ? What type of events did you have.....such as apnoea/hypopnoea/obstructive/central ? Reason being..........APAPs seem to have trouble dealing with hypopnoeas (based on problem with another poster), and if you had a significant number of central events...........APAP will not help you........you might need a BiPAP.": UNQUOTE

And another one, QUOTE: "Autopap does not treat hypopnea as well as as cpap or bipap." UNQUOTE

I don't really remember reading anything like this on "THIS" froum.

What's the truth ???? If this "IS" true, I hope I did not just throw away $725 by buying my Remstar Auto instead of a BiPAP machine.

Tim

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

[NightHawkeye]

There's truth in all of this. None of these machines are perfect. Anyone who tells you otherwise is not dealing with reality. But that's not really so bad. Hey, none of us is perfect, and even folks without OSA don't necessarily sleep perfectly either.

There have been numerous, ongoing discussions here about how one brand of APAP works better for a certain individual than another. There has even been conjecture about the reasons why. (Can you spell FLAME!)

And there are some of us who have used both an APAP and a BIPAP, and find that for one reason or another we do better with a BiPAP. I've also seen where folks have tried BiPAP and then gone back to APAP, presumably because the BiPAP didn't do anything for them, or wasn't as comfortable for them, or maybe for other reasons.

QUOTE: "By what you have posted, I believe you are using an auto adjusting machine ? There could be a situation whereby all your apnoea events are not being cleared..............this can, and does happen frequently with APAPs. There are a number of posts on the forum concerning this. I might add that a significant number of sleep doctors won't prescribe them for this reason.

This can be true, particularly if you have clusters of apnea events, and also have long periods without apneas. If the APAP isn't set for a narrow range, it can't bring up pressure rapidly enough to keep the apnea from occurring. I can see that clearly in my own data. At a higher fixed pressure, the apnea event would never occur. Of course, you'd have to be able to tolerate the higher pressure all night, something that I personally couldn't do because of aerophagia.

Another thing that struck me..........do you have a copy of your original sleep study ? What type of events did you have.....such as apnoea/hypopnoea/obstructive/central ? Reason being..........APAPs seem to have trouble dealing with hypopnoeas (based on problem with another poster), and if you had a significant number of central events...........APAP will not help you........you might need a BiPAP.": UNQUOTE

Tricky area. He has stated a partial truth. I've read conflicting accounts from the experts about this. BiPAP can also increase centrals, so it's not a cure-all. BiPAP-ST is prescribed for centrals, but that is considerably more expensive than regular BiPAP. But then, it also depends on what's causing the centrals . . .

And another one, QUOTE: "Autopap does not treat hypopnea as well as as cpap or bipap." UNQUOTE

True in the same way as stated earlier for apnea. If APAP min pressure is set very low and you only have clustered apneas, then you will probably have events which are not cleared. I know I certainly saw them on a nightly basis while using APAP.

What's the truth ???? If this "IS" true, I hope I did not just throw away $725 by buying my Remstar Auto instead of a BiPAP machine.

With knowledge and choices comes responsibility and decisions. So many questions do not have simple black and white answers. My guess would be that by taking charge of your own therapy you are already doing better than you would have otherwise. I know that I certainly am. Are you getting optimum treatment? If your AHI is under 1.0, like many folks here, that might be as good as it ever gets. Mine isn't under 1.0 though, and I've still got aerophagia, too. I keep trying, and I keep making gradual improvements.

FWIW, I first got a BiPAP-auto, then later bought an APAP, and now use the BiPAP-auto again. Each change improved things for me though. Apnea is sometimes tough, and you have to work through multiple problems - a concept that hasn't fully registered in the sleep industry.

Hope this helps. Good luck with your therapy, Tim.

Regards,
Bill

[Darth Vader Look]

I don't disagree with what NightHawkeye has posted (he was very nice) but I find that a lot of this quoted stuff is just some idiot that really hasn't a clue as to how these machines work:

QUOTE: "By what you have posted, I believe you are using an auto adjusting machine ? There could be a situation whereby all your apnoea events are not being cleared..............this can, and does happen frequently with APAPs. There are a number of posts on the forum concerning this. I might add that a significant number of sleep doctors won't prescribe them for this reason.

If your APAP is not set up properly then this is a good possibility. Most DMEs and doctors don't know the Auto's well enough to set them up properly. They don't even bother to get manufacturer specific operational training on the machines. If they did we would have no need for forums like this one. Proper setup means knowing what your titrated pressure level is and having the machine pressures set up 3cm below and 3cm above that level. If the machine is setup this way you can bet that OSA will be handled just as well as a straight CPAP would or could do it. Doctors will emphazise that the DME's are the ones that are supposed to be all knowledgeable in the workings of xPAPs because that is what they are there for. How much truer can you get. DME's usual setup is leaving the unit run with a wide open span (4-20cm). Just goes to show the incompetence DMEs have. The reason sleep doctors will not prescribe them is from feed back from the evil DME. DME is not making as much profit so best get the doctor's mind off of prescribing them. You want more proof just ask a DME what the 1FL1 and 1FL2 on the P&B 420E Auto's is used for. It took a post by RG and -SWS to get to the bottom of that one.

Another thing that struck me..........do you have a copy of your original sleep study ? What type of events did you have.....such as apnoea/hypopnoea/obstructive/central ? Reason being..........APAPs seem to have trouble dealing with hypopnoeas (based on problem with another poster), and if you had a significant number of central events...........APAP will not help you........you might need a BiPAP.": UNQUOTE

Most newbies couldn't tell heads from tails what their sleep study says. Hell I likely couldn't make that determination either. That's what my sleep doctor is there for. He will tell me if I require a CPAP/APAP, BiPAP or a specific BiPAP (ST). Centrals may require a more specific BiPAP because straight BiPAPs are more so geared for people with higher pressure levels that can't breath against this high pressure. You often hear about people still having problems with CPAPs. They are still experiencing apnea events and can't for the live of them understand why. Well the CPAP is set for one particular pressure and if an apnea event can't be handled by that pressure guess what? DME says bring your machine in and we will adjust it up higher for you. An Auto set properly will handle this situation quite fine thank you very much.

QUOTE: "Autopap does not treat hypopnea as well as as cpap or bipap." UNQUOTE

Again that is just a lot of bull.

Tim, if you purchased an APAP and your doctor prescribed a BiPAP then I wonder who would sell you that with that specific prescription in hand. I am sure CPAP.com or any other online seller of xPAP equipment wouldn't do this at the risk of loosing their business and you can bet that a DME wouldn't do this. Rest assured that your doctor is not going to order a straight CPAP, APAP if a BiPAP is required.

Tim this is the forum to get the straight goods on information. Nothing is covered up, blanked out or removed other than spam and that is a good thing. .

[dsm]

I agree that allowing users to go out the door with an AUTO set 4 20 is a problem.

One thing I do believe (& will publish data on when it all turns up) is that many people are misled as to what an AUTO really does.

Some people mistakenly believe an AUTO can clear an immediate OSA blockage. Not even the manufacturers claim this.

An AUTOs great strength is its ability to prepare for blockages by sensing disturbances as they start to manifest themselves, then they slowly increase pressure in an attempt to pre-empt a blockage. This is their strength.

If AUTOs could prevent blockages in real time then no one would have Enore Pro stats showing the blockages they had.

An AUTO is not always able to anticipate a blockage that may have originated with a shift in sleeping position or some other sudden event.

The best they can do when a blockage occurs is to slowly raise the pressure in the expectation of preempting a following one.

The earlier models (that were even then 'flow-based') would actually wait for a blockage to pass before attempting to increase pressure. Manufacturers were even then aware that increasing pressure during an apnea blockage can be (and generally remains) counter productive.

The principal benefit of an AUTO is to allow a user some relief from the difficulty of exhaling against high cpap pressures combined with the difficulty in managing masks at higher pressures.

A Secondary benefit is the user being able to do their own sleep study. Autos are very good at this for most types of OSA.

DSM

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

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

[Sleepy Dog Lover]

It depends on who answered your post. If it was sleepy dave, and you had all of your results posted, it is probably accurate. Sleepy Dave runs a sleep clinic and generally gives good advice.

[DME_Guy]

IMO, saying one type of machine is better than another is non-sense. The only thing that matters is which machine is best for you for both comfort and medical need. If one type of machine was the best for everyone, I'm pretty sure 99% of the people on this forum would all have that machine. Word would get out eventually.

[Guest]

One thing I do believe (& will publish data on when it all turns up) is that many people are misled as to what an AUTO really does.

Some people mistakenly believe an AUTO can clear an immediate OSA blockage. Not even the manufacturers claim this.

An AUTOs great strength is its ability to prepare for blockages by sensing disturbances as they start to manifest themselves, then they slowly increase pressure in an attempt to pre-empt a blockage. This is their strength.

If AUTOs could prevent blockages in real time then no one would have Enore Pro stats showing the blockages they had.[/url]

I find this to be a curious statement since the manufacturers do claim to trigger on both precursor type SDB events as well as apneas. I look forward to seeing and discussing that data.

[-SWS]

The above was me accidentally logged off.

[dsm]

SWS,

Hi - this is an interesting line.

What are you meaning when you say 'trigger'.

I do believe no AUTO works fast enough to clear an in-flight blockage. Am happy to debate the point as I do greatly respect your insights on this.

I do know that the Sullivan Autoset T was a machine that waited for a blockage to pass before attempting to put pressure up.

Cheers

DSM

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

[-SWS]

The best they can do when a blockage occurs is to slowly raise the pressure in the expectation of preempting a following one.

Okay. Now I think I understand where you are coming from. Yes, I agree there is an issue regarding pressure's rate of change with respect to that static pressure required to clear any given apnea. However, the rate of pressure change will be a constant function, while the required static pressure for clearing apneas will be variable based on how "heavy" each of those "weight variable" apneas happen to be. Some apneas will require a relatively lesser pressure change and will thus be cleared quickly; comparatively "heavier" apneas will require comparatively greater pressure deltas. Those latter apneas will, of course, take much longer to clear based on that fixed rate of pressure change. That is assuming human survival physiology hasn't taken over first and cleared the apnea before the changing pressure gets a chance to clear it. I see this as a continuum of "lighter" apneas requiring a lesser pressure delta to be cleared, heavier apneas requiring a greater pressure delta (and thus more time) to be cleared, and intermediate apneas falling all along the continuum's middle.

Yes, I think it will be great to look at that data. Sounds very neat, indeed.

[-SWS]

SWS,

Hi - this is an interesting line.

What are you meaning when you say 'trigger'.

I do believe no AUTO works fast enough to clear an in-flight blocakage. Am happy to debate the point as I do greatly respect you insights on this.

I do know that the Sullivan Autoset T was a machine that waited for a blockage to pass before attempting to put pressure up.

Cheers

DSM

DSM, very interesting! Trigger being an event detection followed by a response. When an apnea event is detected the pressure response ensues. You can see from my post immediately prior how I perceive that response as a fixed rate pressure delta requiring varying amounts of time to clear an apnea---based on the starting pressure at that trigger moment and the variable weight of an apnea.

[dsm]

SWS,
Lets cut to the chase. I am sure we will both agree on all the lead up stuff re what AUTOs do in monitoring air flow and what they are designed for and their overall benefits.


What I believe will be very helpful (certainly to my understanding) is to take a real world scenario that is likely to occur and anlyse it. If ok with you lets try this one ...


1) User has an AUTO & his supplier sent him out the door with it set 4 - 20 (this happens all the time).

2) User's titration on cpap was say 12 (a seemingly typical number)

3) User is sleeping and the the AUTO has already detected some anomalies and it its intelligent way has boosted the CMS to 9

4) At this point the user rolls onto his back just as the machine hit 9cms and then an OSA incident occurs that in our hypothetical would normally have been prevented had he been on cpap of 12

So what I would like to work through is what does the AUTO do regarding this block and how fast ...

a) Can the AUTO clear this block or will the user have done it long before the AUTO gets to a CMS that will overcome the obstruction

b) Can the AUTO respond rapidly and reinflate the airway

c) Does the AUTO have to go far above our suggested 12 cms


Some givens we can work to (if agreed)

i) That the user's flow limitation is not a central

ii) That the user is a regular user & not someone with unusual breathing patters (unusual for xPAP)

Cheers

DSM

[rested gal]

IMO, saying one type of machine is better than another is non-sense. The only thing that matters is which machine is best for you for both comfort and medical need.

Well said, DME_Guy. Some machines, some masks, some combos of machine/mask are simply not going to suit some people's treatment needs or comfort needs.

Sometimes, for some people, it's just a matter of pressure and other setting(s) not being adjusted properly to suit their medical and/or comfort needs. Not to mention that individual needs can change - during the night, as well as over time.

Sometimes one type of machine, or one brand of machine, is not going to suit a few people at all. But to say that one type (or brand) of machine is "better" (or worse) across the entire apneic population is, as you said, nonsense.

[dsm]

<snip>
And another one, QUOTE: "Autopap does not treat hypopnea as well as as cpap or bipap."
<snip>

On this point there is some area for discussion.

AUTOs are great for reducing the average pressure a user is at over a night's sleep. The reduction benefit is not really to do with inhalation but with exhalation - ( the effort in breathing out and in managing masks & leaks etc:).

AUTOs are cautious about Hypopneas because studies do indicate that a flow limitation not caused by a blockage may not always benefit from the type of steady pressure increase an AUTO can deliver. I understand that this matter is a key decision point in the algorithm of most AUTOs. It has to decide what type of event is occuring. In the case of pure flow limitations caused by centrals, not even a standard (S mode) Bilevel is likely to get the person breathing again. Most Bilevels will just sit there on EPAP. In a similar situation an S/T mode Bilevel tries to 'kick' start breathing again by flipping from EPAP to IPAP after a 'timed' period, this flip sends an increased rush of air to the user and hopefully restarts them breathing.

AUTOs really are good at anticipating OSA events and upping the pressure in advance of a blockage. SWS & I are currently are exploring the scenarios of what happens when a sudden OSA event occurs.

DSM

[-SWS]

DSM, there are a lot of extremely interesting subpoints in this technical discussion that need to be discussed thoroughly. I intend to delve into each one of those as a matter of interesting subject matter in the upcoming weeks. However, for now I wanted to trade some of my own "in a nutshell" observations.

1) 4-to-20 cm settings: Very problematic for patients in general, yet an interesting topic unto itself. Interesting for several reasons: One is that manufacturer field reps have repeatedly claimed there is no reason to narrow the range. To me that implies an algorithmic design objective that was endeavored, initially believed to be met or achieved, yet in my opinion never truly achieved across a patient population with diverse SDB signal manifestations. It also implies the DME's misunderstanding in the viability of that 4-to-20 cm pressure range is probably seated in that incorrect information conveyed from the manufacturer. Also interesting because theoretically it is possible for an APAP algorithm to achieve widespread efficacy with a 4-to-20 cm range. There are some patients who can achieve satisfactory results with a 4-to-20 cm range, but far too many who cannot---very likely to the surprised dismay of some manufacturers. I would like to explore that theoretical design objective----explore when it works and why as well as why it falls short all too often. That's a big topic for a separate post.

2) APAP Response to an Apnea: this may be one area where our views currently contrast a bit. I believe an APAP's algorithmic response to apneas are crucial----that an APAP does, indeed, necessarily respond to apneas as part of an overall treatment strategy. I believe an APAP's proactive and reactive algorithmic routines are both necessary. Because there is an issue regarding pressure's fixed rate response time to variable apneas, the two points you have highlighted become key: a) heavier apneas can and do go unaddressed, and b) any APAP's algorithm must be heavily leveraged toward preventing apneas. This is another great topic that I'd like to thoroughly discuss in a separate post. While this may be the only subtopic we disagree on, it still sounds as if we currently concur on the vast majority of this topic---with the possible exception of characterizing whether that APAP algorithm can be apnea responsive versus purely proactive as I think you maintain.

3) Hypopnea Triggering: Why don't APAP's trigger on hypopneas? I think we both agree on this subtopic in it's entirety. However, I'd still like to re-explore the issue of "algorithmic caution" regarding both the detection and refrain from triggering in response to hypopneas in light of an important complex sleep disordered breathing (CSDB) study that Harvard medical researchers have very recently brought to light. I believe APAP manufacturers have contended with these CSDB sleep event distributions for quite some time, never fully realizing exactly what the effect was or why it was occurring---only recognizing the CSDB sleep event distribution as a very small yet statistically significant occurence in their own studies. I believe their very cautious algorithmic response to hypopneas reflect their own cautious attempts to cope with that CSDB effect. I'd love to explore this issue in a separate post, hoping the CPAP user group may eventually get around to asking the manufacturer's about their views of this recently discovered CSDB condition.

4) Technical Limitations: In another post I discussed how I believe probability-based SDB signal analysis was a basis for today's technical limitations. I would also like to explore the concept of yet other technical limitations that have to do with an APAP's central design strategy. Because the APAP manufacturers have each taken different algorithmic approaches to treating our SDB conditions, these manufacturer-specific differences in central design strategy will necessarily lead to key differences in "technical limitations" versus "bugs". Those technical limitations that are the result of differences in central design strategy (re: algorithms) will thus also necessarily yield different efficacy patterns across an entire SDB patient population. Those differences in central design strategy are thus precisely why brand X APAP can yield very different results for any given patient than brand Y APAP. This discussion will also underscore the caveats of generalizing the operation and treatment results of an "APAP" as if it were a hypothetical generic device.

The bad news is that my time constraints don't allow me to spend nearly as much time on the message boards as I used to. Yet I think all these topics, and yet others, warrant detailed discussion---especially in light of what I perceive to be a great opportunity regarding the new CPAP user group one day soon being able to address some of these key issues with manufacturers. I'm going to come back to this thread in the upcoming days, and open other threads for technical discussion in the upcoming weeks. My posts will not be nearly so prolific as they once were since my time constraints are absolutely terrible. Yet slow posts can be better than no posts. I think your time constraints may be more limiting with the CPAP user group work at hand. So maybe you won't mind my slow response times since you'll be busy as well.