how good are cpap/apap machines at measuring ahi?

I talked to my sleep doc today about the possibility of replacing my Remstar Pro with a Pro 2, which measures apneas, hypopneas, etc., presumably using the same techniques as an autopap. He expressed considerable scepticism about the numbers produced by the pro 2 and discouraged me from going that route. He doesn't seem to be the (all too common) type of doctor who actually wants their patients to remain ignorant so they're easier to deal with, and I think his concern about the quality of the data produced by these machines is genuine. My question is, is his concern justified? What do we really know about how well these machines measure apneas, hypopneas, etc.? I love reading scientific journal articles, so feel free to point me towards any that are out there or any other available info (or threads on this forum that I've missed.

Thanks to all of you for all the helpful posts. The online cpap community has been a wonderful help to me as I adjust to this new way of life.

Here are some interesting links pertaining to this topic (thanks to rested gal):

"Sleep Doctor" doesn't like autopaps(5 page topic)

and

Finally slept through the whole night....(3 page topic)

I'll continue looking for more...

More: here's a study:

APAP is a useful and accurate tool that successfully titrates nasal CPAP pressures in a nonattended setting.

Here's a an excerpt from Mayo Clinic Proceedings:

Autotitrating CPAP devices can be recommended; they are perhaps most useful for patients with marked differences in pressure requirements due to body position or sleep stage. The proprietary systems within these units allow dynamic variations in delivered pressure in response to changes in pharyngeal pressure, airflow, or vibration; therefore, the lowest appropriate pressure can be administered for the given circumstance. These systems provide equivalent positive effects on sleep and breathing factors at lower mean pressures compared with standard CPAP systems and have been shown in some, but not all, studies to produce modest increases in compliance.

For entire article: Mayo Clinic Proceedings
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And this excerpt taken from another article:
http://www.medscimonit.com/pub/vol_9/no_8/3329.pdf

For the treatment of the obstructive sleep apnea syndrome,
automatic CPAP treatment on the basis of forced
oscillation technique (APAPFOT) has proved equally
as effective as constant CPAP therapy [12,13]. For the
former, a significant reduction in the mean treatment
pressure and improved acceptance in comparison with
constant CPAP have been reported.
While no relevant differences in polysomnographic data
were found between APAPFOT and bilevel treatment,
both modalities brought about an improvement in daytime
sleepiness as measured with the Epworth Sleepiness
Scale, which, however, was significant only under
APAPFOT. A further reason for the superior acceptance
of APAPFOT may concern the pressure profile under the
two modalities. Thus, despite identical efficacy, under
APAPFOT, the mean treatment pressure vs. bilevel treatment
was reduced in the overall group by a mean of
3.1±1.8 cm H2O. The maximum automatic CPAP applied
was lower than the fixed inspiratory bilevel pressure.
With APAPFOT, therefore, a substantial reduction
in pressure was possible, which was more marked than
observed in studies with CPAP in unselected patients.

Thanks for those articles, neversleeps - how did you find them?
O.

I googled auto adjusting cpap therapy.

I love to search!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Here's another:

The mean treatment pressure during APAP was significantly lower than during CPAP treatment (6.0 +/- 2.0 vs. 9.0 +/- 1.8 mbar; p < 0.001). There were no significant differences between APAP and CPAP treatment in any parameter of efficacy or acceptance. APAP treatment with this device controlled exclusively by FOT is well accepted by the patients and permits an adequate treatment of OSAS without the need for invidiual CPAP titration.

from:Biomed Tech (Berl). 2003Mar;48(3):68-72

sanctacaris wrote:... What do we really know about how well these machines measure apneas, hypopneas, etc.?

Quite a bit, actually!

The pro II isn't auto so it will only record what happened. Its dumb otherwise. Just a straight cpap with a memory. Am I wrong about this ?

Anyway, Why not get an auto and benefit from its 'wisdom' . It can actually 'do something ' about it instead of just watch it happen. And for only $15 more .

:twis ted:

Thanks for all that info, neversleeps! It'll take me a while to digest. But at first glance it sure seems like there's plenty of evidence that autopaps work, which would suggest that they're pretty good at detecting apneas and hypopneas and that the technology is more or less "there". It's depressing reading all the posts about ignorant, arrogant doctors.

Crisp,

Technically, any of these machines that have sophisticated "data storage" (whether it be a smartcard or whatever) can ONLY record "what happened". It's all "after-the-fact" information. The difference being that the APAP's have the ability to change pressures based on what is happening with your breathing, snoring, etc., but only records what it did during those events. Other than that, the REMstar Pro 2 CPAP and APAP (REMstar Auto w/Cflex) record virtually the same data (there's just more "stuff" to record with the pressure changes, etc. on an APAP). They both have CFLEX capabilities, ramp features, smartcard storage, etc.

I agree that an APAP is probably a better way to go if you NEED that kind of machine. If I had it to do over again, I MIGHT have gotten an APAP, but I don't know if my situation would warrant its use. My Pro 2 seems to be getting all of my numbers down at my particular setting.....in other words, I think it's "training" my body....slowly but surely. I doubt that I'll ever get ALL of my numbers to 0.0, but as long as I can keep them pretty close, I'll be satisfied. I also like the fact that it seems to be helping me lose weight.

Sleep tight.....and don't let the bugs bite.

Den

Now I'm mixed up. One very knowledgable person on this site contends the APAP machine DOES sense your breathing disruptions and stops the event and now someone else is saying all it does is record what happened.

Which is true?

[quote="Sleepless on LI"]Now I'm mixed up. One very knowledgable person on this site contends the APAP machine DOES sense your breathing disruptions and stops the event and now someone else is saying all it does is record what happened.

Which is true?

He did say this, which means the pressure change DOES try to cover the apnea and stop the event "The difference being that the APAP's have the ability to change pressures based on what is happening with your breathing, snoring, etc., but only records what it did during those events"

Yes, but is it changing the pressures as a result of or before the episodes start tp prevent them? That's what I'm not getting. Some say, yes, before it starts, it will pick up on the algorhythms and change the pressure to prevent, and I think now Wulfman is saying that all it does is record the data but use that data to try to prevent future episodes, not a particular event before or as it's starting.

Sometimes I feel like such an idiot when I can't understand what others are saying. I am not, and have never been, much of a scientist so maybe that's why. I work in an entirely different realm of the professional world out there having nothing to do with algorhythms and scientific data and reactions, etc. (they wouldn't let me in that area of the working world).

Lori,

You're so right!!! What was written was verrrrrry confusing!

This much I know to be true. APAP varies the pressure BOTH as a PREVENTATIVE measure, and as a CORRECTIVE measure. It is a matter of scientific fact, not a matter of opinion.

THe following is from the very definition of APAP:

CPAP is set for one continuous pressure. An AutoPAP can be set to deliver a range of low/high pressures, customizable within 4 - 20 cm H2O.

An AutoPAP differs from a CPAP in that an AutoPAP uses algorithms to sense subtle changes in the user's breathing and deliver only the amount of pressure necessary to keep the airway open.

An AutoPAP automatically varies the pressure to prevent and/or correct sleep disordered breathing events - apneas, hypopneas, air flow restrictions, and snores.

Computer software is available for AutoPAP machines, which will allow a user or clinician to download the recorded data into a PC. This data can be put in report form to track treatment results.

Let me be frank. (I know of no other way to be...) I believe Wulfman's comment was in defense of his machine, the REMstar PRO II CPAP, which chrisp pointed out was not an auto and therefore couldn't adjust treatment and could only report what happened. chrisp's statement was a fact.

So Wulfman, in defense of his machine, (and in a friendly "mincing of words" discussion with chrisp) gets into semantics:

Technically, any of these machines that have sophisticated "data storage" (whether it be a smartcard or whatever) can ONLY record "what happened". It's all "after-the-fact" information.

Which simply points out THAT ALL DATA (including a history book which records what were at one time live, malleable events) IS A RECORD OF WHAT HAPPENED. But make no mistake about it, an auto machine does make adjustments (both preventative and corrective) as an event IS ABOUT TO HAPPEN, OR HAPPENS. In the morning you download your stored data and you see what HAPPENED.

Hmmm.... I just re-read this.... Can't decide if it is clarifying or even more confusing..... Do you get what I mean about what I think Wulfman meant when he wrote what he wrote in response to what chrisp had written?

Let me ask that a different way. How much wood would a woodchuck chuck if a woodchuck could chuck wood?

Neversleeps,

No, you clarified it to the point and very well, thank you very much. And in answer to your question, a woodchuck would chuck all the would he could chuck, IF a woodchuck could chuck wood .

Thanks, NS.