CPAP vs APAP - one sleep doc's view

SnoreNoMore2005 · Post by **SnoreNoMore2005** » Thu Mar 16, 2006 9:07 pm

I've been an APAP user since June of 2005. I went for a regular check-up to my sleep doc this week armed with my MyEncore reports which show an average rating of less than 2 AHI. My APAP settings are 7 - 12 with an average of 8cm.

My sleep doc suggested I switch to an 8 cm CPAP rather than using APAP. His theory is that when you use APAP your brain is constantly having to adjust your respiration to accomodate the various changes in pressure throughout the night. He says with the straight CPAP, your brain becomes accustomed to the unchanging air pressure and has to work less which is less taxing on one's sleep cycle.

I don't know if I buy that theory, but it is the first explanation I have ever heard on why a CPAP might be better than an APAP. I just wanted to share his theory with everyone.

Does anyone agree or disagree with his assumptions?

SnoreNoMore2005

Neurosurgery NP · Post by **Neurosurgery NP** » Thu Mar 16, 2006 9:16 pm

Doesn't make sense to me - it is the machine that is adjusting your respiration rather than your brain. The machine actually doesn't adjust your respiration - just your airway resistance - opens your airway. I know that I do see variations in pressure - I can see it when I download my info - if I lie on my back, I require a higher pressure to keep my airway open. If I have a few beers, I also see higher average pressures.

Goofproof · Post by **Goofproof** » Thu Mar 16, 2006 9:18 pm

[quote="SnoreNoMore2005"]I've been an APAP user since June of 2005. I went for a regular check-up to my sleep doc this week armed with my MyEncore reports which show an average rating of less than 2 AHI. My APAP settings are 7 - 12 with an average of 8cm.

My sleep doc suggested I switch to an 8 cm CPAP rather than using APAP. His theory is that when you use APAP your brain is constantly having to adjust your respiration to accomodate the various changes in pressure throughout the night. He says with the straight CPAP, your brain becomes accustomed to the unchanging air pressure and has to work less which is less taxing on one's sleep cycle.

I don't know if I buy that theory, but it is the first explanation I have ever heard on why a CPAP might be better than an APAP. I just wanted to share his theory with everyone.

Does anyone agree or disagree with his assumptions?

SnoreNoMore2005

hecate · Post by **hecate** » Thu Mar 16, 2006 11:16 pm

The studies show something different. Auto CPAP allows you keep your pressure down untill you need it. The only time your pressure is changed should be when it is needed.

Liz

Darth Vader Look · Post by **Darth Vader Look** » Thu Mar 16, 2006 11:28 pm

I would be wondering about his feeling on BiPAP machines and units that have exhalation relief like C-flex and EPR? Does his thinking still hold up on those?

Wulfman · Post by **Wulfman** » Fri Mar 17, 2006 10:39 am

SNM,

Does anyone agree or disagree with his assumptions?

Possibly.......with "qualifiers".

I can only speak from the standpoint of using a fixed-pressure CPAP, and have never used an APAP. I also qualify this as it's something I've WONDERED about. I'm not saying this is definitely my opinion or belief.

SO.....from my experiences in the last 10 months, I've WONDERED if maybe the straight CPAP might re-train a person's breathing. And, since an APAP is a REactive machine as it adjusts to a person's breathing (or lack thereof), it has less of a "training" effect on one's system.

One reason this comes to mind is when I have taken naps in my recliner (without a CPAP) since I started my therapy, my wife informs me that I hardly ever snore anymore and my breathing is very quiet (no gasping episodes anymore).

OK, all you APAP users.....don't beat me up for this.....it's just a thought I've had.

Best wishes,

Den

Goofproof · Post by **Goofproof** » Fri Mar 17, 2006 10:45 am

Wulfman wrote:SNM,

Does anyone agree or disagree with his assumptions?
Possibly.......with "qualifiers".

I can only speak from the standpoint of using a fixed-pressure CPAP, and have never used an APAP. I also qualify this as it's something I've WONDERED about. I'm not saying this is definitely my opinion or belief.

SO.....from my experiences in the last 10 months, I've WONDERED if maybe the straight CPAP might re-train a person's breathing. And, since an APAP is a REactive machine as it adjusts to a person's breathing (or lack thereof), it has less of a "training" effect on one's system.

One reason this comes to mind is when I have taken naps in my recliner (without a CPAP) since I started my therapy, my wife informs me that I hardly ever snore anymore and my breathing is very quiet (no gasping episodes anymore).

OK, all you APAP users.....don't beat me up for this.....it's just a thought I've had.

Best wishes,

Den

Wulfman · Post by **Wulfman** » Fri Mar 17, 2006 11:19 am

Goofproof wrote:I too have noticed this, and I feel rested, but I took it being I am setting in a chair instead of laying down so my airway stays open better, and I probably not sleeping as deep because it's for shorter periods.

Jim,

One night (sometime back) when I asked my wife how my nap went, she said I hadn't breathed for 3 hours......

Most of my naps HAVE been much shorter since being "on the hose".....darn!.....and I definitely don't take as many as I used to.....darn, again!
Oh well, I AM feeling much better with this therapy.

Best wishes,

Den

capt · Post by **capt** » Fri Mar 17, 2006 2:23 pm

Using your sleep doctor's logic about the power and control that the "brain" has adjusting to an apap, raises one big question. If the "brain" has so much control, why does it not prevent and control apnea in the first place?

dsm · Post by **dsm** » Fri Mar 17, 2006 3:18 pm

My 1st reaction was that "it doesn't make sense" but as I thought more about it it struck me that I may be experiencing an example of what he is talking about.

My regular mask is an Ultra Mirage F/F mask & this seems to work pretty well for me now & I seem to sleep well with it.

But, I have a Malinkrodt 'Adams Circuit' mask that I obtained & really got to like - it is so superior in comfort etc: to any other nasal pillows mask I have tried (Breeze, Swift, etc:). It has soft straps to hold it in place, I don't have trouble with my nares as I do with the others, I can sleep in almost any position.

I used this mask for 3 weeks & was I believe getting used to it, I thought I would never go back to my f/f mask, but then I began to experience increasing mouth air escapes - I am a mouth breather but thought I had this problem licked - so after 3 weeks that problem re-emerged & wouldn't go away. I had to switch back to the F/F mask.

So last night I decided to try the AC (Adams Circuit) mask again but to tape my mouth up.

During the night my wife kept leaning over & looking at me & putting her hand on my face (she is like a mother with a new baby, any time my breathing patterns change she tends to get woken up). During last night she asked what had I done to my mask as my breathing was 'all over the place' . I know she has not had a good nights sleep & I feel mine was restless.

On reflection I can say that as much as I love the AC mask, I have a lot of difficulty adjusting to it even though I like the feel of the air being injected into my nares vs the sometimes struggle to breathe when congested & using the F/F mask.

So my point here is, is my experience backing up this doctor's observations ?

I am not sure but am wondering.

Cheers

DSM

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): mirage, swift, Nasal Pillows

ozij · Post by **ozij** » Fri Mar 17, 2006 10:30 pm

The brain actually does "control" the apnea. An osbtructive apnea is the result of your relaxed muscles and tissues being affected by gravity: they sag. Whe you sleep, your brain lets go of its control of voluntary muscles, they relax, but the minute it senses you haven't got enough oxygen coming in - zap! it wakes you up enough to clear the obstruction.

Which is why without therapy, on the one hand, we don't choke to death, but, on the other hand, we don't sleep too well either.

CPAP therapy is supposed to help us sleep better by taking care of the obstructions. The doctor's point - better constant higher pressure than dynamically variable - is not unsensible. I don't know enough about the subject to say whether it is valid or not.

I read on this forum that some people respond to pressure decrease with hypopneas. Which fit in with my experience and when I narrowed the range (lowered the top in my case) I started sleeping better.

The point is that anyone with an automatic machine and software can try both ways -and nobody with a simple machine can to that.

A word about trying: unless the change is distinctly catastrophic - try for at least a week - preferrably more.

O.

roztom · Post by **roztom** » Sat Mar 18, 2006 12:59 pm

While we're on the topic consider this:

MY understanding is that with an APAP you may be able to keep lower pressure until an event is detected that the machine responds to.

With CPAP you keep a higher constant pressure.

Doesn't it seem like CPAP would be more preventative keeping a "constant" pressure to prevent the collapse of the airway while APAP only responds after events are underway?

Is the APAP more of a compromise but allows for more comfort because of the operation at lower pressure some of the times?

Tom

Guest · Post by **Guest** » Sat Mar 18, 2006 2:30 pm

I think the effectiveness of APAP vs CPAP in treating OSA depends on the particular individual's breathing patterns and how well they are interpreted by the particular manufacturer's algorithms. This is exemplified in the study derek did with his own machine and by the data he references:

derek wrote:CPAP is better than APAP (for me..)

For the past three weeks I've been doing an experiment, comparing my nightly data using CPAP wiith that from the previous three months on APAP (REMSTAR Auto with C-Flex). Although the "experiment" is still a work-in-progress, I am convinced that I get significantly better therapy from CPAP. Here's the scoop:

As most of you know, I have been plotting my data using MyEncore, and I have frequently shown the following graph showing how my AHI depends on pressure:

This curve is based on 700 hours of APAP, with the minimum pressure set between 7 and 9 cm H2O. Now the shape of this curve has always bothered me for a couple of reasons: 1) The whole basis for the APAP algorithms is that the AHI should decrease with pressure. I was concerned that if I ended up on the positive slope above 10cm, if I had some event (snore?) that raised the pressure, then I was in fact in a worse position, and would be even more likely to have another event. In other words, on the positive slope we have a positive-feedback situation which can only make things worse, and even lead to pressure runaway - which I have found a few times. 2) I wondered if this curve really represented me, and was not an artifact of the APAP pressure control algorithm.

So I decided to do a study on myself using the CPAP mode. I decided to concentrate on the central region and have been buiding up AHI performance data for pressures of 9, 10, and 11 cm. Each night I have my wife choose one of the three pressures at random, and I looks at the total results in the morning. Here is the CPAP pressure-AHI plot for three weeks worth of data:

Now compare this to the same pressure range extracted from the first chart (ie 3 months of APAP data).

The plots are almost identical indicating that, at least in this data range, the APAP AHI-pressure plot provides a good picture of my true AHI-pressure dependence.

Now here's the thing: my nightly AHI's are significantly lower on the CPAP at any of the three pressures than on APAP at 9 - 14 cm, (I know that they are already low. ) and what's more the night to night variation in AHI is much, much reduced. I don't have the statistics yet, but looking at my nightly plots it is obvious that there is much less variation. I put this down to the fact that the nightly meanderings of the APAP pressure actually are inducing apneas/hypopneas.

So here's the question. If anybody has a concave AHI-pressure plot like mine, why would they ever want to set the maximum APAP pressure above the minimum in the plot (10 cm in my case)? You are, by definition, not going to get any better treatment from higher pressures. And if you can tolerate the 10 cm pressure, why bother with the lower pressures?

Why not just set up in CPAP mode at the pressure with the lowest AHI? I'm going to stay in CPAP.
derek

So if you have an APAP, you can conduct a series of experiments in different modes to see which gives you the best treatment. It may be APAP mode, it may be CPAP mode. Just be sure to give it at least a month at each setting for statistically relevant data.

roztom · Post by **roztom** » Sat Mar 18, 2006 2:49 pm

Thanks. Great post.

Who is Guest?

Tom

roztom · Post by **roztom** » Sat Mar 18, 2006 2:57 pm

Which number is the number. Where the AHI is the lowest on the MyEncore AHI/Pressure chart or where the ENcore Plus 90% pressure is at?

Tom

CPAP vs APAP - one sleep doc's view

CPAP vs APAP - one sleep doc's view

Re: CPAP vs APAP - one sleep doc's view