Data interpretation and relevance of AHI

Help me refine my understanding of these graphs.
The charts below are fairly typical of my event distributions.

In the top image below (graph of 8 hours), there are 3 Central Events and two Hypopneas between midnight and 5:30 AM (calculated AHI of 0.91).
Then, as seen in the second image (expanded to a 30 minute window), there are 4 Central Events between 5:34 and 5:45 AM (calculated AHI of 20).
In the pressure chart of the first image, it looks like there was an interruption in the pressure graph just before this event cluster.





So, here are the questions I have:
1) On other nights, I have seen the same cluster (Centrals only) without the interruption preceding it. Are these clusters likely due to REM sleep? (Right or wrong, that is the interpretation I have been following...and the basis of the following questions)
2) Investigation of the detailed data for that night shows interruption in the flow happened between 5:20 and 5:24AM and I suspect it was a potty trip. Is it likely that the events between 5:34 and 5:45 reflect REM sleep?
3) My AHI numbers fluctuate from night to night. I have a minimum of 1.3 and a maximum of 3.2. When I look at the nights with higher AHI's, I either see two separate clusters like this or a cluster which is sustained for longer duration. So, if my presumption that this is during REM is correct, it seems that on nights my AHI was high, I got lots of REM and on nights it was low, not so much. So, is a high AHI really bad if I see this pattern consistent with extended REM time?
4) If so, is there anything I can do about these clusters of Centrals?

As background, during my original (non-CPAP) sleep study my REM AHI was 25.9 and nonREM AHI was 5.4, with a Total Sleep Time AHI of 8.3.

Thanks for the Help!

I see nobody has yet replied so I'll take a stab at these

Rogue Uvula wrote:1) On other nights, I have seen the same cluster (Centrals only) without the interruption preceding it. Are these clusters likely due to REM sleep? (Right or wrong, that is the interpretation I have been following...and the basis of the following questions)

It's difficult to tell whether it's REM sleep or not, only really a sleep test would be able to determine this being wired up to a whole host of other sensors.

Rogue Uvula wrote:2) Investigation of the detailed data for that night shows interruption in the flow happened between 5:20 and 5:24AM and I suspect it was a potty trip. Is it likely that the events between 5:34 and 5:45 reflect REM sleep?

Same as above

Rogue Uvula wrote:3) My AHI numbers fluctuate from night to night. I have a minimum of 1.3 and a maximum of 3.2. When I look at the nights with higher AHI's, I either see two separate clusters like this or a cluster which is sustained for longer duration. So, if my presumption that this is during REM is correct, it seems that on nights my AHI was high, I got lots of REM and on nights it was low, not so much. So, is a high AHI really bad if I see this pattern consistent with extended REM time?

I presume looking at the graphs you tend to get more Central Apneas than Obstructive? I only see one obstructive there from this night and the rest are Centrals. If this is the case, then the S9 although great for detecting Centrals, isn't going to be able to help as much as it can for Obstructive Apneas. It uses pressure to splint open the upper airway to provide it easier to breath and less likely to have the upper airway being blocked. For Centrals it still responds, it gives you the oxygen you need and it does ramp up the pressure to ensure you get the oxygen but it's not necessarily going to bring you out of the Central Apnea as it's your brain effectively forgetting to breath as opposed to a physical blockage.

Rogue Uvula wrote:4) If so, is there anything I can do about these clusters of Centrals?

I would check more of your graphs, increased pressure has been known to generate more central apneas in some people, and if you find a cluster of more centrals when the pressure increases, you might need to think about reducing the pressure. For you it might not be the case (from what I can tell on the graph above it doesn't seem the case as you have clusters of centrals at lower pressures).

Rogue Uvula wrote:So, is a high AHI really bad if I see this pattern consistent with extended REM time?

An AHI below 5 is still good, so I wouldn't worry too much unless your AHI is going above 5 or even 10 or 15. Ultimately we all like to get our figures down as much as possible, with Centrals its a lot more difficult to do this vs Obstructive apneas which are much more easier to control.

Thanks
Dave