Morning Numbers

[shanzlik]

They should have stuck with calling them clear airway apneas, which was a more accurate statement since the S9 isn't reading brainwaves.

I have experienced more CA events on higher pressures. When I went from 9 to 12, my CA events tripled at first, and they're still about double what they were. There was an article in ResMedica stating that CA events tended to rise once the pressure is 10 or more.

[PaulaO2]

Yep, this happens to just about everyone. During my sleep test, I went from an AHI of 3 on pressure of 7 and an AHI of 36 on pressure of 9. So we started at 8 and increased it after a month or so.

[SuperSleeper]

We had a huge discussion on the old forum on whether or not increased CPAP pressure actually causes central apnea events or not. Some claimed higher pressure has no effect upon centrals. Much discussion back and forth, but if I remember correctly, no one could come up with a completely unbiased scientific study (with a large sample group) that showed with any degree of certainty that increasing pressure indeed leads to centrals.

Still waiting for someone to come up with a study that shows either conclusion with convincing data. There is plenty of anecdotal evidence and personal experience on both sides, but nothing I've seen yet that brings it to a solid conclusion either way via scientific method with a large sample group.

[PaulaO2]

Yep. It is all anecdotal. It would be a great study to try!

And mine were all central events. It went from 8 OSA to 36 CSA.

[zonk]

There was an article in ResMedica stating that CA events tended to rise once the pressure is 10 or more.

This is an old article as the older APAP didn't treat apnea above 10 cmh20 as thought apnea above 10 are central best to leave them alone but the S9 enhanced AutoSet algorithm differentiates between OA and CSA. It uses Forced Oscillation Technique (FOT) to determine whether the airway is open or closed during an apnea.

Central Sleep Apnea Detection and the Enhanced AutoSet Algorithm
http://www.resmed.com/au/assets/document...-paper.pdf

[projman65]

Thanks for all the replies. My second night on the S9 with pressure settings of 9-16 was a little worse. AHI 6.8 and leak 11.2

Because I am a curious person, I kept thinking about the last 4 years and my fixed pressure of 11. I really wanted to know how I was doing...and the only way to find out was to actually re-create the conditions of my old CPAP machine on my new S9. So I did last night. I set it to CPAP and set my pressure to 11.

Surprisingly, the numbers were better than the first 2 days on Autoset...AHI 5.2, Leak 8.6

So now I'm confused. Any ideas?

Thanks.

[PaulaO2]

Leave. It. Alone.

Seriously.

Yes, you used another machine for several years. But it is a different machine. Autoset vs basic. EPR vs nothing. Different manufacturer and different algorithm. And you keep changing things. Pick something. Either Auto with a good range (whatever the sleep doc said to use) or straight CPAP with the pressure you had before. Then leave it. Go two weeks on one or the other. One or two nights of data is very useless.

In addition to the AHI, there's the 'how do you feel' factor. Then there's the 'how my day went' factor. And the 'how did I sleep' factor. Then there's mood, environment, comfort, etc etc. Each one of these are variables that effect each other. No two nights are the same. We don't dream the same, we don't sleep in exactly the same position for exactly the same amount of time.

This is why sleep data from our machine at home is much better when looked at over a period of time.

For example, I got an oximeter (measures the blood O2) Monday. The first night, my O2 was great. Never went below 94%. Second night, lowest was 84%. Last night was even worse and it went down to 80%. OMG!! I'm getting worse!! No, I'm not. First night was a regular night. I wasn't overly tired, I slept relatively well for 8hrs. Second night, I went to bed angry and frustrated at something. I slept about 6hrs. Last night I was exhausted from the bad sleep the night before as well as I wasn't feeling well from dinner. I am not making any conclusions from the data until I've used it for about two weeks. I can see a slight trend, though, and will not be surprised if my final average is below what it should be.

You need to do the same. Pick one or the other and collect data for at least two weeks.

[shanzlik]

The portion of the article I mentioned - that higher pressures can cause more central apneas - is not invalidated just because they've changed treatment algorithms. Dr. Berthon-Jones stated, "I mentioned before that the higher the pressure, the more central apneas you will have."

He then went on to talk about not treating apneas if the pressure was already over 10 (in the older algorithm). I realize that the algorithm used to treat apneas with their current CPAP machines is different from that in the study, and that they have changed which levels they are and are not treating, but that doesn't change the statement he made linking higher pressures to higher central apneas.

The FOT still can't distinguish whether a non-obstructive apnea is truly a central apnea, with associated lack of respiratory effort and brain activity, or whether it is something else. Sighing, talking, etc. can appear to the machine to be central when they really aren't. FOT didn't change that.

It's certainly better than what they had, but it's still prone to some false positives. If they relabled central to open airway, it would be more technically accurate. In my opinion calling them all central makes some people think they have a problem when thy may really be perfectly normal.

[Sleepster]

Thanks for replying Zimlich. I know it's only been one day...we'll see how the numbers look in a 2-3 weeks. but it's interesting what you said about the increased apneas with the increased pressure. I wonder if that's common with others.

When I had too many central apneas they lowered the pressure to reduce them. It worked.

So, based on that experience, I would say I would say that too high of a pressure can increase (central) apneas.

If I were you I'd do two things. First, wait and see what happens in the next couple of weeks. Second, see if the AHI is composed mostly of central apneas.

If, after a couple of weeks, you still have a AHI above 5 on a significant number of nights, and the AHI is due mostly to central apneas, then I would be concerned that the pressure might be rising too high.

[Sleepster]

The ResMed S9 AutoSet will not raise pressures in response to a central sleep apnea event.. it basically ignores them. It will only raise pressures in response to an obstructive event.

That surprises me. I would have thought that it would lower the pressure in response to an excessive number of centrals.

What does cause it to lower the pressure? A lack of obstructive apneas?