4cm Pressure to Find Consistent Pre-Treatment Baseline?

Since events with same names (AHI, FL, RE, etc.) mean different things on a sleep study vs. on my CPAP machine, I'm wondering if setting my maximum and minimum pressures at 4cm would give me a rough idea of how my machine reports the number of the various types of events I have when I go untreated. If I could establish what a "typical" night looks like on my machine when untreated, I could see how CPAP therapy helps me (at least numerically, if not in my personal experience) when I use it at therapeutic levels.

Would this be a dangerous thing to do? I don't think it would be; 4cm of pressure is more than none, which is what I used to get pre-treatment and what one gets during a sleep study. I would only do it until what represents a typical night for me emerges, probably a few to several days.

I've just been very confused about how the AHI means something different on my sleep study as it does on my machine. I would like to know how my machine translates what my sleep study calls a high RDI and low AHI.

Also, the results of my sleep study may be slightly inaccurate, since some things about that night were atypical: sleeping in a new place, room less dark than my bedroom at home, noisy staff in the hallway, staff charging full-speed into the room when I'm half asleep to adjust my nose tube, sleep-onset insomnia when I usually have sleep-maintenance insomnia, etc.

Am I correct in thinking that setting my machine to low/minimal treatment would help me find out how my machine depicts a typical night and would provide me with a consistent baseline?

Napstrss,
I think I'm missing something...but why would you expect any difference at a pressure of 4 then at your prescribed pressure? Your machine is going to use the same method/algorithm despite the pressure setting...or that's how I see it.
J

jamiswolf wrote:why would you expect any difference at a pressure of 4 then at your prescribed pressure? Your machine is going to use the same method/algorithm despite the pressure settin

Hmmm..... I'm not sure what you're saying. I'm thinking that if I cap my pressure at 4cm, then I will have more events than at my treatment level—maybe almost as many as when untreated. That way I can see how my machine describes my situation when I am untreated.

I've been confused from the get-go about which events I should be looking at on my machine. My PSG said my AHI was 0.2, but my RDI was 45 events/hour. So my doctor is treating me with CPAP for what used to be called UARS, not apnea. She said my RDI was calculated based on my RERAs since I had so few OAs, Hs, and CAs. She wants to address the arousals triggered by respiratory efforting (since I rarely reach total throat closure but have a lot of awakening events from breathing issues). But my machine does not measure RDI. So I'm wondering how an untreated night gets reported by my machine in terms of number and types of events. I figure a min/max of 4cm is as close as I can get to untreated. Then I could see which types of events are significant for me and on which I should focus on addressing with correct pressure.

I'm in the midst of experimenting with my pressure levels anyway b/c a few people here thought I could go higher than my Rx of 5-8cm and/or go straight CPAP. It would be good to know if I should aim for what my machine is calling REs or AHI or what.

Am I making sense yet? Is this a hare-brained scheme?

This makes sense to me, your first post made just as much sense too...I am certainly no CPAP expert, but I have wondered about doing something similar myself. I am also curious how much the odd testing environment made a difference in my results and I would think that if you had the machine set very low it would give you your normal nights results. But I'm not entirely sure.

4 cm of pressure is still pressure and will have some therapeutic value so it won't be an absolute "true" baseline but it is as close as you are going to be able to get using the machine.

I understand what you are wanting to see if you can see by doing this. It may not be as remarkable of a baseline since your pressure needs aren't hugely different from 4 cm but if you can stand to breath easily at 4 cm to try it, I don't see why you shouldn't give it a try. Your situation is different from most of us who would have some major lengthy events with major oxygen drops if we tried this.

If I tried this I would see event city all night long...Wouldn't be pretty and I know I would feel like I had been in the toilet all night with 50 plus events an hour in REM and oxygen dropping to low 70's.

Just remember that 4 cm does offer some therapy value and thus it can't give you a true "pre cpap" baseline to go from. But it might show you something you could sink your teeth into and help you sort through your unique situation.

LARS929 wrote:This makes sense to me, your first post made just as much sense too...I am certainly no CPAP expert, but I have wondered about doing something similar myself. I am also curious how much the odd testing environment made a difference in my results and I would think that if you had the machine set very low it would give you your normal nights results.

Pugsy wrote:it might show you something you could sink your teeth into and help you sort through your unique situation.

Thanks LARS and Pugsy. I just tried a week at 6.5-8.5. This week I'm trying straight 8. Next week I'll try straight 4 to see what's what.

Pugsy wrote:I know I would feel like I had been in the toilet all night with 50 plus events an hour in REM and oxygen dropping to low 70's.

Good heavens, darling girl! What do you do when you have a cold?

I don't see any harm in trying but I don't think you'll get any useful information either. 4 cm is nowhere near being equivalent to no treatment. What did your sleep study show at that pressure? I had a huge reduction in AHI at the lowest pressure even thought my end pressure ended up being 14. Your prescribed pressure is barely over 4.

OK, so I'm a little slow.
You want to stimulate events to guage your machines ability to recognise them? To give a "baseline'.

A Rera is really just a hypopnea...slight difference in definition related to % of O2 saturation drop...but essentially the same thing. So wear a recording oximeter to gather one more channel of data. And be sure to sleep flat on your back to ensure maximum events.

Go for it.
J

napstress wrote:Good heavens, darling girl! What do you do when you have a cold?

You know I have had 2 maybe 3 colds since starting cpap therapy. I haven't missed a night using my nasal pillows when I had a cold. I didn't die a thousand deaths because I didn't have a full face mask and I slept about as well as I would have slept with a cold without the mask. Load up on decongestants, Nyquil and a little Afrin (if needed), crank up the humidifier full out and I found I actually could breath better on the machine than without.
I think the added moisture helped.

Only time I have slept without the machine was one night when I had the 2 P's (puking and pooping). Fell asleep on bathroom rug for about 4 hours. Desats were the least of my problems that night.

I don't think it will hurt you to do 4cm, but I am not sure your data will be particularly revealing. Even if it shows hypopneas, hypothetically, at 4cm, that's not going to tell you what they are at 8cm or whatever.

His idea is to get some idea of his AHi while not being treated, $ cm should show you that within the limits of using 4 cm over 0 cm, if you can't have a AHI under 5 at 4 cm, truly you need the correct pressure from the machine to stay healthy.

What he want's is a Poor Man's am I cured test. I couldn't stand anything under 10 cm anymore but that's just me, I've adapted to XPAP @ 15 cm just fine, now that's normal for me.

I wouls suggest a O2 meter to check for destats, I'd trust the results as well as a lab sleep test as long as the leak rate is under control during the test. Jim

Sure it's not a lab sleep test, as it doesn't go down to 0 cm, but it should be a fair indicator of need for treatment, with the O2 test added in.