Zero AHI At Sleep Study, Not So Good At Home

My sleep study and titration on 11/15 indicated no apneic episodes and no hypopneic episodes at a pressure of 6cm. I received my CPAP setup on 11/18, and immediately got at it. I've got the same mask, pressure, etc.... as in the titration, but am now reading average for apneas (.6) and hypopneas (6.2) at home via my Smartcard and ResScan software. This week, I've experienced hypopneas up to 14.

Any idea of why I'd be at zero during my titration, and all over the board at home?

Thanks,
Brian

maybe leaks? dunno?

but there are many here who could better help you figure it out if you could post the report from your ResScan software, specifically your nightly leak and AHI plots.

hang in there, it can take some time to work out all the fine details of the treatment ... but well worth the effort.

forgot to mention ... you should not always expect zero indicies EVERY night.

there are treatment and non-treatment related variables that affect the values such as medications, diet, amount of time you sleep on your back or side.

the point is that you should use your data in terms of averages (weekly) and/or trends (monthly) ... don't get too hung up on the night-to-night values.

At the sleep study you had more advance equipment that was more accurate in determining what constitutes an AI or AHI event.
Your CPAP machine has more limited capabilities and hence uses a different algorithm to determine the events.
Even different manufacturers of CPAP machine score events differently. Resmed are known to report higher number of AHIs than most others.

Yeah. I'll bet they didn't use a ResMed machine to titrate you.


Den

Visited with My DME dealer today. No great ideas there, but walked out with a F&P Forma Full Face Mask. Interesting though.... apneas seem to increase when leakage is low. Most of the folks were scrathing their heads. I just want to sleep.

Thanks all!

Brian

In the sleep study, more criteria has to be met to qualify as an apnea or hypopnea. Could be your events are not causing you to desat enough to be classified in the sleep study, even if the air flow criteria was met.

Deeper sleep tends to bring on more apneas/hypopnas. Perhaps you are sleeping a lot more deeply at home than you did during your sleep study. Many people do, myself included.

I wouldn't worry at all about the HI (hypopnea index) with a ResMed machine being even as much as 10.0 as long as the apnea index (AI) was very low -- like AI below 1.0. I'm not a doctor though. That's just my opinion about "hypopnea" reporting with ResMed machines.

As others mentioned, the definition of hypopnea used in sleep studies, and the definition of hypopnea used by our treatment machines is not the same at all, so it's not surprising there could be quite a difference in what's reported from a PSG sleep study, and what's reported from our treatment machines.

Drops in SpO2 (measured by the little clip on your finger at the sleep study) as well as arousals (identified by the EEG patches attached to your scalp at the sleep study) are taken into consideration at the sleep lab when identifying hypopneas. Neither oxygen saturation nor brain arousals are taken into consideration in the definitions of "hypopnea" our machines use.

Even the airflow measurements that both the PSG study and different brands of machines track can have different definitions regarding the amount of diminished airflow it takes before a "flow limitation" will qualify as a hypopnea.

That said, if it were me, and I'd been prescribed a fixed pressure of 6 cm from a sleep study, I wouldn't hesitate at all to raise the pressure myself to as much as 10 or 11, to see if more pressure made me feel better. I'd raise the pressure especially if I were using ResMed's EPR for exhalation pressure relief. And I'd raise the pressure one or two full cm's at a time, giving each change at least 3 or 4 days.

Doesn't look like you're having any leak problems.

Thanks for the great, informative post, Rested Gal. Much appreciated.

I asked the DME dealer to crank up the pressure a bit, without much luck. Planning on contacting my MD's office today to get the go ahead. The full face mask (F&P Forma) idea didn't work out too well last night. In order to keep a seal, I had to strap it too tight. As a result, it hurt everywhere it contacted my face. Went back to my Swift LT and got about 9 hours on it, with better numbers.



Is it normally difficult to get the go ahead to increase the pressure? As I'm keeping a pretty close eye on the results, seems like the best way to manage the program.

Have a great day!!!!
Brian

Your numbers looks pretty good to me if you're not having leak issues, and it seems like you are not (with the Swift LT anyway).

Remember, that AHI is composed of both Apnea and Hypopnea index. Obviously full blooded apneas are more significant events than hypopneas, and a lot of hypops push up an AHI. They are less serious, and with an autopap, it can generally catch those events and resolve them, with the proper pressure setting. Your numbers look just fine to me from what you posted. An AHI under 5 is considered NORMAL for an adult. One doesn't have to have an AHI of 0, or even close to it for one to feel rested, and properly treated. So, keep it up, and check periodically with your professional, and feel free to post here with questions.

BrianR4743 wrote:...The full face mask (F&P Forma) idea didn't work out too well last night.

Consider the RespCare Hybrid that covers the mouth and has nasal pillows; it does not cover the nose or trouch the forehead. Comes with 3 sizes of oral cushion, 3 sizes of pillows that sit at 2 different heights (bottom of nose to upper lip varies quite a bit amongst faces) so getting a good fit is fairly easy.