Accuracy of Encore versus Sleep Study

lemon · Post by **lemon** » Mon Mar 05, 2007 1:50 pm

I've been on cpap for 3 years and been through 5 studies, so I've been analyzing my data for a while. My problem seems to be that I have a high REM AHI, for which even the highest pressures titrated don't correct. This is probably why I'm still tired even though I comply with CPAP and have worked out many of the kinks.

On my sleep studies, each REM period shows about 50 hypopneas an hour, even at high pressures. Encore on the other hand, only shows about 5-10 a night. They're at about the right places, where my REM cycles might be, but still only a fraction of the number there should be.

Has anyone else noticed big differences like this between sleep studies and their Encore data?

Of course I'm sure there are differences in how hypopneas are measured, but the fact that so many are missing seems like it renders the APAP functionality useless. It also makes it hard for me to gauge my treatment.

rested gal · Post by **rested gal** » Mon Mar 05, 2007 2:39 pm

lemon, the absence of most hypopneas on your Encore Pro data is an indication that the machine is treating you well. It's preventing most of the events you saw on your sleep study. When it prevents an event, the event simply doesn't happen; thus no "event" to report.

The 5 or 10 hypopneas you see reported are the ones that are getting through despite the machine trying to ward them off.

The fewer events (apneas/hypopneas) you see on your data, the better.

Linda3032 · Post by **Linda3032** » Mon Mar 05, 2007 2:43 pm

Lemon, are you saying you get 50 events during the sleep studies while you are using pap? Are you also using the same mask?

Goofproof · Post by **Goofproof** » Mon Mar 05, 2007 2:50 pm

What settings are you using on APAP? What is your AHI? The hybrid has a high vent rate, are the leaks under control, and what is your avg leak rate. Jim

Wulfman · Post by **Wulfman** » Mon Mar 05, 2007 3:22 pm

lemon wrote:Encore on the other hand, only shows about 5-10 a night.

You WANT it to show more??? Sounds like you're disappointed.

Den

lemon · Post by **lemon** » Mon Mar 05, 2007 3:55 pm

To answer the questions.

I had 50 events per hour during REM sleep only. So my REM AHI was about 50. My overall AHI was about 8. My Encore AHI average is 1-2.

I'm currently set to the same constant pressure as the highest I was titrated, so I would theoretically expect my results to be in line with the study. I also have Encore data from the same period of time I was titrated, and I would certainly expect that to be in line. Same mask/habits as I used in study, etc.

I've been using constant pressure rather than APAP mode most of the time, since most of my events didn't seem to be detected anyway. So the theory that the auto is taking care of my events, doesn't seem to hold up.

Am I dissapointed that there aren't more events detected? A little. Because I still feel very tired during the day, much more than 5-10 events a night would suggest! And since the results are inconsistent with the in-lab sleep study, it offers a good explanation of why to say the machine isn't detecting all hypopneas the sleep lab was. Unfortunately if my REM AHI does explain my problems, I'd need a very high pressure to cure those REM issues. Higher than the highest pressure titrated (>15). It's gotten so bad that I'm seriously considering surgery right now as an alternative.

lemon · Post by **lemon** » Mon Mar 05, 2007 4:09 pm

In answer to the question on my leak rates, I spent a lot of time on hybrid leaks and I've gotten to near perfection with the new straps. I don't have my data in front of me, but for pressure 15 I average about 60 L/min.

By the way, thanks for all your quick respsonses. THinking about what I went through with leaks and everythign reminded me how helpful this board has been to me.

SleepySandy · Post by **SleepySandy** » Mon Mar 05, 2007 4:16 pm

Your situation is puzzling.

I'm wondering some things, but please understand I'm very new to this process. I hope my questions aren't dumb.

I do understand what you're saying about the high number of events in the sleep study and not seeing those on EncorePro. You indicated those 50 REM events per hour were at your prescribed pressure. Were they obstructive apneas, hypopneas, or central apneas? I swear I just read that a pressure that's too high can cause central apneas... Does EncorePro recognize central apneas? Could the titration study have been tracking central apneas that EncorePro isn't recognizing?

lemon wrote:My problem seems to be that I have a high REM AHI, for which even the highest pressures titrated don't correct.

I'm puzzled about this because I don't understand why they wouldn't adjust your pressure more during the titration study to get the REM events under control.

Was this explained to you in terms of not being able to correct the REM events? Has your doctor explained the logic of prescribing a pressure that doesn't seem to have your events under control?

NightHawkeye · Post by **NightHawkeye** » Mon Mar 05, 2007 4:17 pm

lemon wrote: It's gotten so bad that I'm seriously considering surgery right now as an alternative.

Whoa! That's pretty drastic. I daresay there are other less drastic (and less expensive) possibilities you can try first. Here are some which come to mind:

1) Post a copy of your EncorePro data on-line so folks can see what it looks like and offer suggestions.
2) Try different settings on your current machine (which way to go? You haven't stated enough info for anyone here to make an educated guess yet.)
3) Try a different APAP - The machines operate differently, perhaps another manufacturer's algorithm would work better for you.
4) Try the BiPAP-auto - The BiPAP action gives higher pressures but also makes breathing at those pressures a lot easier.
5) Talk with doc about getting a Timed/Synchronous machine. That kind of machine will force you to breathe. Kinda hard for hypopneas to sneak through on that.

Not even trying to offer you a suggestion on what approach to try other than to say that there are sure a lot of things I'd try before going under the knife myself again. Last surgery I went through had too many things which went wrong (and that's a common occurrence, by the way).

One other thing: It does sound like the Remstar is stopping a lot of your hypopneas, but perhaps not all. You definitely don't want to be seeing an AHI of 50 under treatment. If you could post a picture of you Encore Pro chart that would really help.

Regards,
Bill

lemon · Post by **lemon** » Mon Mar 05, 2007 4:31 pm

SleepySandy wrote:You indicated those 50 REM events per hour were at your prescribed pressure. Were they obstructive apneas, hypopneas, or central apneas? I swear I just read that a pressure that's too high can cause central apneas... Does EncorePro recognize central apneas? Could the titration study have been tracking central apneas that EncorePro isn't recognizing?

They were almost all hypopneas. No centrals. My doctor did say that REM was probably responsible for my current daytime sleepyness, but I didn't get a clear answer on why they didn't go to a higher pressure on the study. I guess they titrated until my overall RDI was low, even though my REM RDI was still very high. To be fair, it did bring my overall RDI way down. I no longer have any events in non-rem sleep over pressure 9. I also wake up less during the night, so it's not like it does nothing.

On a side note, I'm not sure if the machine would catches centrals. I would think it might, since as I understand it centrals you still stop breathing, just not due to obstruction.

-SWS · Post by **-SWS** » Mon Mar 05, 2007 5:56 pm

Lemon, did you happen to see that answer by Rested Gal? Your sleep study showed untreated AHI while Encore Pro data shows your residual or treated AHI.

These "before" and "after" AHI indexes should not be the same. Note that sleep labs tend not to send a patient out the door with a treated AHI of 50. However, an untreated AHI of 50 or so is not at all uncommon.

With that said, if you still have serious daytime fatigue or somnolence issues, be sure to address those symptoms with your physician(s). If your physician ignores any outstanding symptoms that are truly debilitating, then it is time to get a new physician in my opinion. Good luck!

Linda3032 · Post by **Linda3032** » Mon Mar 05, 2007 6:06 pm

I keep reading Lemon's post that says, "On my sleep studies, each REM period shows about 50 hypopneas an hour, even at high pressures."

That indicates to me that she is having 50 hypopneas per hour even with treatment during the sleep studies.

Maybe I am all confused (which is normal for me). To me, she is asking why "with treatment" the sleep studies show alot more HI's than Pro does.

Maybe Lemon can clarify if that's the case, and state again what she's asking.

Sorry if I'm confusing this whole issue.

Offerocker · Post by **Offerocker** » Mon Mar 05, 2007 6:11 pm

Lemon:

I've had two sleep studies, two different labs. Two different results.

I now give more credence to my APAP's captured data, Encore Pro, and Encore Pro Analyzer, and how I feel.

I also agree it is worth addressing with a different doctor, since you are not feeling as well as you would like.

rested gal · Post by **rested gal** » Mon Mar 05, 2007 6:24 pm

Linda3032 wrote:I keep reading Lemon's post that says, "On my sleep studies, each REM period shows about 50 hypopneas an hour, even at high pressures."

That indicates to me that she is having 50 hypopneas per hour even with treatment during the sleep studies.

Ahhh...ok, I missed "even at high pressures". Thanks, Linda!

I guess a person would need to see the graphs and charts from those titration nights to really get an idea what was going on during REM.

-SWS · Post by **-SWS** » Mon Mar 05, 2007 7:08 pm

My old "cognitive issues" have me missing whole bunches today (true). Linda, thanks for pointing out key details!

Lemon, don't be afraid to get second or even third medical opinions from other doctors if you haven't already. Plenty of good opinions and advice already presented in this thread IMO.