CPAP making AHI go up?

[budleigh]

Hi there,

I was diagnosed with mild OSA a while ago (AHI of 7-8), and even though it was mild, my day-to-day life was significantly impacted. I was prescribed a CPAP machine, and all signs were positive after my first sleep study with it. When I got it home, however, things started to go wrong.

The Phillips Respironics model I have has feedback info like AHI and leak - the AHI to me being the crucial number. On the first night, my AHI was 7.8. The next night it was above 8. The next it was 10, then 11..I stopped there. I would revisit it occasionally after mask adjustments or pressure adjustments (I was prescribed a pressure of 7, and went to an auto pressure of 6-10), but the AHI would remain always above 7.8.

There was one glimmer of hope when I got my mask readjusted by a Stanford sleep technician during a third study, after which my AHI went down to 4.0 for a few days. It then started to go back up, and is now hovering around 8 and 9.

The only advice I've heard is 'increase the pressure', but surely a prescribed pressure of 7 would not be as far off as more than 3. What is going on here? I'm all for wearing the mask, but if it isn't improving my AHI, what's the point?

[Budleigh]

Just a quick followup:

my docs have seen all the reports and have said nothing about central apneas. The mask has 0 leaks.

[DreamOn]

My initial thought was that your leak rate may be high, but then you added the followup post where you said that your mask has zero leaks, so that doesn't appear to be the problem.

You mentioned that your machine is currently set at auto pressure of 6-10 and that your prescribed pressure was 7. Have you tried CPAP pressure at 8 for a while? I'd try that for at least a few days (a week would be better), and see if your results are any different. Many of us do better at set CPAP pressure. The other possibility is that your prescribed pressure was way off. What is your machine-reported 90% pressure?

It would help us to know exactly which Phillips Respironics machine you have, and which mask also. Does your machine have A-Flex or C-Flex, and are you using that?

[Julie]

What's going on may be that having any Cpap air being blown in results in your mouth opening when asleep (unless it did that prior to Cpap anyhow) and all the air getting lost that way. Try taping x 1-2 nights to see if it helps and, if so, consider getting a full face mask. If you already have one though, then obviously something else is happening, but see if that makes a difference.

[DreamOn]

I agree with Julie. I had assumed that your machine was reporting no problem with leaks, since you mentioned that it has that capability. If you are losing therapy air from either your mask or mouth, that can definitely affect your therapy. And keep in mind that you could be sleeping right through leaks and never know it.

[budleigh]

thanks for the replies.

I did sleep with a chin strap for a few nights with the same results. The machine's 90% pressure number is 7.5, which I'm not sure how to interpret :\

[Budleigh]

I saw some interesting threads on the humidifier affecting AHI reported by the machine - I'll try having that turned off tonight. I'm usually on 1-3 and, to be honest, I find it pretty uncomfortable with rainouts and whistling.

[GumbyCT]

Hi there,

I was diagnosed with mild OSA a while ago (AHI of 7-8), and even though it was mild, my day-to-day life was significantly impacted. I was prescribed a CPAP machine, and all signs were positive after my first sleep study with it. When I got it home, however, things started to go wrong.

The Phillips Respironics model I have has feedback info like AHI and leak - the AHI to me being the crucial number. On the first night, my AHI was 7.8. The next night it was above 8. The next it was 10, then 11..I stopped there. I would revisit it occasionally after mask adjustments or pressure adjustments (I was prescribed a pressure of 7, and went to an auto pressure of 6-10), but the AHI would remain always above 7.8.

There was one glimmer of hope when I got my mask readjusted by a Stanford sleep technician during a third study, after which my AHI went down to 4.0 for a few days. It then started to go back up, and is now hovering around 8 and 9.

The only advice I've heard is 'increase the pressure', but surely a prescribed pressure of 7 would not be as far off as more than 3. What is going on here? I'm all for wearing the mask, but if it isn't improving my AHI, what's the point?

Several questions -
Which mask make/model? It should be on a label on the headgear.
What size mask?

Which model machine? The machine model should be written right across the top of it.

Is this machine used? Or a loaner? How many hours on it?

Where are you getting this leak rate number from?

The AHI number is a 7/30 day average - being an average could it go up as you use it?

What is your sleeping position?

[DreamOn]

I did sleep with a chin strap for a few nights with the same results. The machine's 90% pressure number is 7.5, which I'm not sure how to interpret :\

From Respironics:

"90% Pressure is defined as the pressure at which the device spent 90% of the session time at or below. For example, if the device recognized airflow for 10 hours, and 9 hours were spent at or below 11 cm H20, and 1 hour was spent above 11 cm H20, then the 90% Pressure would be 11 cm H2O. This screen displays the average of these individual nightly values of 90% Pressure over a 7 day and 30 day time frame."

I assume that your 90% Pressure number of 7.5 was the 7-day average (you didn't say), and that you were using auto pressure of 6-10 during that entire time. I would try set CPAP pressure at 8 for a week or so and see what your results are.

But, more important, you need to make sure that you're not leaking air from your mask or mouth. Chin straps definitely do not work for everyone, and some are much more effective than others too. You may need to tape your mouth, at least temporarily, in order to rule out that mouth leaks are a problem. There's some good info on mouth leaks, taping, etc., here: viewtopic.php?t=8011. Or, you may need to try a full-face mask. If you are losing therapy air from either mask or mouth, then that lost air isn't doing its job of keeping your airway open, which can result in higher AHI numbers. Also, if your leak rate is excessively high, it can make your other results numbers (AHI) inaccurate. You may be sleeping through mask leaks too.

Can you give us some idea of your System Leak numbers? Also, it will help if you would answer Gumby's questions regarding machine and mask. I'm not very familiar with the Respironics machines myself, but there are others here that can help you with that.

I just wanted to comment on your AHI during your sleep study too. That was just a snapshot of one night, so it may or may not have been an accurate representation of your typical sleep at home. Are you feeling any better during the day since beginning therapy? And how long have you been using the machine? Do you have a copy of your sleep study results? Was there any problem with central apneas noted? Did you have obstructive apneas or mostly/all hypopneas? Were there excessive limb movements or arousals noted?

[Janknitz]

The problem with Philips Respironics machines is that you do not get enough information on the LED screen to be able to really adjust anything. You get ONLY 7 and 30 day averages for AHI, no information on what is going into the AHI score (the score adds up obstructives, hypopneas, and centrals but you have no idea which of these is part of the score), and the "large leak" means a blast like a jet plane for a very long time to even show on the screen. 0 leaks on the LED screen means nothing.

In order to understand why your scores are what they are, you need the software--Encore Viewer 2.0. That will show you exactly what is going on. It's the only way to really tell if leaks are a problem, if you are perhaps having pressure-induced centrals, or if something else entirely. You may be having "clusters" of events during REM sleep, your mask may be leaking like a seive when the pressure goes up, or there could be a whole host of other reasons you are not getting ANY benefit from the therapy.

my docs have seen all the reports and have said nothing about central apneas.

You probably can't rely on the doctors--even the venerable Stanford Sleep Center doctors--to check the minutiae of YOUR therapy. That's your job if you want to be certain you're getting effective therapy for all of your time, effort, and expense.

It would also help if you would post what mask you are using, because if leaks turn out to be the problme (I suspect they are) we can help.

[Budleigh]

Hey all, thanks for the help. I'm at work at the moment but I'll wander back and get all the model names at lunch. I also suspect something like centrals or leaks are happening even though the machine isn't telling me, but I've been barred from accessing the data in memory so I could see a more detailed report, and my doctors say I'm unable to change settings like pressure or cflex to aflex because of some locked 'admin mode' that only the doctors and technicians can use. Am I being duped here as well? I'd love to have that level of involvement with this, I think my remoteness is making me less inclined to continue treatment.

[Budleigh]

@DreamOn, as far as my sleep study reports go, the events are mostly hypopneas with I think 5 total apneas during the night out of 45 events. No movements, slight teeth clenching and 100% supine.

I know that on my first study with the cpap at the clinic my AHI measured by them was 2.1. I felt great. So I think it has everything to do with the mask, it's fit, leaks and how I'm wearing it..is that a reasonable conclusion to draw?

[DreamOn]

Budleigh, when you're able to give us the exact model of machine and mask that you're using, we can give you more specific suggestions.

I'm going to have to leave any machine-specific discussion to those more familiar with the Respironics machines. Once we know which exact model you're using (and whether it's a newer System One or an older Respironics version), then someone here can send you the information you need to access the machine data, but you'll need to register first (it's free), so you can receive a Private Message (PM).

But, as Janknitz said, the Respironics machines can't give you the detail that you really need on the LCD screen. It's my understanding that the System Leak number on the LCD screen only tells you if there were leaks that were so large that it affects your statistics -- and that's not reported night-by-night either, only over 7- or 30-day periods. The software will give you more information than you can get from the machine's LCD screen. Once we know which specific Respironics machine you have, then someone can confirm which software you need to purchase.

If leaks are your problem, they could be coming from either your mask or your mouth -- or both. It's also possible that you may do better using a slightly higher set CPAP pressure rather than APAP. It would be helpful to see what's happening via the software reports.

[Julie]

Duped? Well... depends on how you look at it, but it's not a bad word . We can help you learn to adjust your machine whenever you'd like to try it. Do NOT let the DME's or doctors or anyone tell you it's either illegal (please!), or that you won't understand it all anyway (no comment) or that the machines are unreliable so it won't matter... those are the 3 usual arguments.

[Budleigh]

Again, thanks all so much for the support. Thought I'd be at sea with this forever.

The mask I'm using is a ResMed, with the only words I could see being 'Medium Mirage SoftGel'. It is an over the nose mask. http://www.resmed.com/us/products/mirag ... c=patients

The CPAP machine is a Phillips Respironics REMstar Auto A-Flex system one...whew. Looks like this: http://www.cpap-supply.com/REMstar-Auto ... ds550s.htm

I'm also registered now for PM's.

Thanks!