High AHI toward morning - am I the only one :)

I've recently started using a "non-brick" CPAP machine, the Remstar Pro with C-Flex. Now that I can see my nightly data (using Sleepy Head) it looks like I have very high AHI readings during about the last 2 hours of sleep, i.e., toward morning, but almost none before this. I will discuss this with my sleep doc but would like to know if this is something others have encountered. I will experiment with possible causes (mask fitting, chin strap etc.), but I suppose I may need an oximeter to tell me if the high readings are real. Another solution may be a CPAP machine that adjusts pressure according to number of apnea episodes? Thanks for any advice/comments.

The 2 most common causes of an increase in events at certain time periods of the night are
1...supine sleeping...sometimes we might roll over onto our backs
2...REM stage sleep
or someone might have a combination of both

It's common for our OSA to be "worse" in REM sleep or when sleeping on our backs and it is also common to perhaps need more pressure during those times than we might need during other times of the night.
My OSA happens to be much worse when in REM stage sleep (documented on the sleep study).

Those wee hours of the morning (2 or 3 hours before we wake up) also happens to be when we go into REM stage sleep more frequently and the REM stages will last longer.

Go here and scroll down the page a little and on the right side is a typical hypnogram that shows the various stages
http://en.wikipedia.org/wiki/Sleep
and you will see what I mean about REM stages.

The solutions...either more cpap fixed pressure all night or get an apap machine and let it auto adjust the pressure as needed for those increased events.
If you think you might be on your back you could try staying on your side but sometimes that is easier said than done.
We have no control over REM though so I prefer to go the apap route since I know for sure that my worst OSA is in REM.
I have found that sometimes I need a lot more pressure during REM and sometimes I barely need any increase.
How much more you might need....I don't know. It depends on how many you are seeing in those wee hours of the morning.
I assume you are seeing some clustering....You might only need 1 or 2 cm more cpap fixed pressure to break up the clusters...all depends on just how bad the clusters are or you may be like me and sometimes need a LOT more pressure to break up the clusters.

Which model PR S1 CPAP are you using?
Is it a 450 or 460? The model number is on the bottom of the blower unit. A 3 digit number with maybe DS, REF or P in front or behind it. If it is a 460 model that machine has some limited apap capabilities so you could maybe see just how much pressure difference there is to deal with those events.

Finally...just how many are you seeing during those wee hours of the morning?
What is your current pressure now?

Oximeter use may or may not help you. Not everyone will have significant desats associated with apnea events especially if they are short lived and the number in the cluster isn't huge.

Thanks for your advice Pugsy. I'm generally a side sleeper, so I suppose I can rule out supine sleep causes. You're right, my OAs are clustered, usually about 2 or 3 of 20-30 min duration each - usually but not always during last 2 hours of sleep. Based on the hypnogram you point to I'd guess that my episodes of OA are during REM sleep. My pressure setting is constant at 14 cm after ramping to this from 6 cm during the first 15'. Since I'm already at 14 cm fixed I'll consider (with my doc) an APAP machine that adjusts pressure as needed.

I'm using a REMstar Pro Model 460P. I'll look into what I can do with its APAP capabilities. I recently was diagnosed with heart failure probably related to long-term atrial fibrillation, and seemingly my sleep apnea. Even with my clustered REM events I've not experienced any (admittedly subjective) atrial fibrillation since I started using CPAP about a month ago. I should note that I've had the REMstar Pro machine only about a week, after starting with the REMstar Plus "brick" machine.

Your advice is very helpful. Thank you!

If you don't have the provider/clinical manual for your PR System One 60 Series Pro CPAP (model 460) you can request it here.
http://www.apneaboard.com/adjust-cpap-p ... tup-manual

Just follow the instructions and this is what you would request
Respironics PR System One 60 Series REMstar Pro with C-flex+

In the manual it explains about the trial APAP mode. It's a 30 day trial but I think it can be reset up to 5 times to get an additional 30 days with each reset....or at least that is what was available in the past the 5 resets.
A reset involves erasing all prior therapy history off the machine though, so just be aware. Not a huge deal if you have the SD card containing all the data and the software.

The wee hours of the morning was when I would most often see pressure increases and any clustering myself.
Sometimes also at the first REM stage which is usually around 90 minutes after sleep onset.

My "daily driver" is a brick, so I don't have long term data, but I did do a 2 week in home titration study with an APAP, back in Sept. I had AHI increases from 4-6 AM. At first it had me a bit puzzled. After a little research, I discovered that my dogs getting restless during that time, is the likely source. I tested the theory by sleeping in another room for 3 days. No AHI increases were recorded.

Is it possible that something is happening to arouse you from sleep (may not be fully awake), during those last 2 hours?

Did you ever figure this out. I have very high AHI almost always between 6 am and 730 am. It also happens to be when I need to get up for work.

Mouchet - are you asleep or awake at that hour (when you 'have to go to work')? If awake, what you read or deduct from the machine's 'results' are not valid... you don't breathe the same way when awake and you shouldn't rely on any numbers you see then.

Mouchet wrote: ↑

Sun Jul 22, 2018 8:14 am

Did you ever figure this out. I have very high AHI almost always between 6 am and 730 am. It also happens to be when I need to get up for work.

As was told to me by a very good sleep tech, "It just happens this way to some people, nobody's ever been able to tell me why".

I have this also, but looking at the waveforms, It appears to transitional central, as I am waking and falling back to sleep.