Sudden increase in peak AHI

[ohwhatanight]

I've been on CPAP for 3 years and have never seen this kind of spike before. Most of the events are hypopneas, usually clustered together in about an hour period. My tidal volume also looks different. No big leaks. No illness or congestion. No new medications but I have recently lost over 6o lbs (weight loss surgery in Nov.) Any ideas what could be causing such a sudden increase? Should I raise or lower my pressure?

(The gap in data is because my card ended up corrupted. I had to format a new one.)

[Pugsy]

Can't tell anything or offer any ideas just by looking at the overview charts.
How about sharing the detailed daily report for a good night and one of the most recent bad nights?

[ohwhatanight]

Here is a recent night. I've had several that looked similar to this lately. Thanks!

[ohwhatanight]

Here is the rest of the screen for the same night.

[Pugsy]

Whenever we see clusters of events at some time and nothing else going on at other times then we think "something changed" because the pressure was fine for the other parts of the night and not for a small part of the night. What changed to obviously need more pressure during that time.

The 2 most common culprits for clusters like this are supine sleeping or REM Stage sleep or maybe a combination of both.
It's common to have significant pressure needs differences when it comes to supine sleeping or REM stage sleep.

If your worse clusters seem to be more frequent in those wee hours of the morning the my first thought is REM stage sleep but it wouldn't be impossible for it to be supine sleeping or even a little of both. I happen to fall in the REM stage sleep OSA is worse and sometimes I need significantly more pressure during those times when compared to non REM time. In my case supine sleeping doesn't seem to make any difference because I did an experiment early on in my therapy where I built a wall to make sure that I absolutely didn't roll over onto my back. That experiment showed me that sometimes I would still need higher pressures but sometimes I didn't need quite as much. I was using an APAP machine at the time and it was easy to see the change in pressure needs.
I had similar clusters like yours when my minimum wasn't quite optimal in APAP mode...a little increase broke up the bad clusters and then the machine could increase as needed and maintain the break up of the clusters.

Since your machine is a cpap only machine you don't have the choice to use less pressure part of the night and let the machine go higher the rest of the night. You are going to need more pressure to break up those clusters.

Now as to why the marked change from the past reports...I don't know why unless it is maybe related to sleeping position. Are you on your back more now? Change in meds? Weight gain?
I would assume that REM sleep itself is probably still the same as it was in the past. I know that in my case I didn't always see a significant pressure change in what was probably REM stage sleep and I wasn't on my back so I don't know why there would be such a wide difference in pressure needs.

So something changed...and it affected your pressure needs during part of the night and not the other parts of the night.
This is one of those situations where having auto adjusting pressures might come in handy then you could continue to use the lower pressure for the bulk of the night and let the machine auto adjust as needed.
Since you don't have auto adjusting capability that means you are going to need to use more pressure all night. Fortunately your pressure needs aren't horribly high and there's a good chance that 1 or 2 cm more will break up the clusters enough so the reports don't look so ugly.

Now if you think it might be related to supine sleeping then you could maybe try doing something so as to stay off your back and see if that resolves the issues without increasing the pressure. Easier said than done sometimes.
If you already never sleep on your back then that leaves REM stage sleep as the likely culprit and we have no control over REM sleep so that leaves a pressure increase as the only option.

[ohwhatanight]

Thanks for such a great explanation! I don't think I sleep on my back, I would have back & neck pain if I did. I also have almost no snoring now, and I had quite a lot until just a month or so ago and if I rolled onto my back it would wake me up. So maybe it is REM. That seems most likely.

You asked what has changed - like I said, no new meds, in fact I am off of several that I was on before. The only one that would affect sleep is that I am no longer taking Ambien. No weight gain instead I have lost over 60 lbs in the past several months. I would think that would decrease my AHI instead of increase it. Diet, of course has also changed with my bypass surgery, but for the good. I eat much healthier, and have no more GERD. All blood work is great. However the rapid change began right at the same time as my surgery. I had general anesthesia - could I have aspirated something? I also have sarcoidosis, but have not had any symptoms for a couple of years. But then again, when I was diagnosed I wasn't having symptoms either. I would think lung issues would show up more evenly throughout the night though, right?

I'll try bumping up my pressure for a few nights and see how that does. I really want to avoid another sleep study unless nothing else helps. I was only able to sleep 3 hours at mine, so they won't get nearly as good of a picture of what is going on as I can see from my own data over the course of weeks. I've moved since then too and don't have a new doctor here.

[Pugsy]

Actually even though our gut reaction to significant weight loss would be "less pressure needed" I have seen lots of people come here and say they need more pressure. Not sure why unless with the reduction in weight the airway tissues sort of get more floppy and saggy similar to what happens to our under arms with a lot of weight loss. Things are used to being stretched out from the adipose tissue and with the loss of the adipose tissue things sag more and don't necessarily shrink back. Kinda like an inflated balloon looks when you let the air out of it.

It's also possible that maybe with the Ambien now being absent that you are maybe getting a little more REM sleep....it's a maybe.

Either way...no matter what the reason is...the fix is likely going to be a little more pressure when we see an increase in OAs or hyponeas.