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+--- Thread: Another FNG (estimating untreated AHI using CPAP at 4 cmH2O) (/Thread-Another-FNG-estimating-untreated-AHI-using-CPAP-at-4-cmH2O)
Another FNG (estimating untreated AHI using CPAP at 4 cmH2O) - tomhole - 03-01-2012
Newbie here. Had a sleep study done 4 years ago. Doc said I didn't sleep well but had no apneas. Snored like a lumberjack and woke up 40 times an hour, but had no real decreases in O2 saturation. Felt sorry for me and prescribed a CPAP but wouldn't diagnose me with OSD or anything that would allow me to get insurance to cover the CPAP. I was retiring from the Navy and busy getting a new job and left it at that.
Since then, my wife has kicked me out of the bedroom and I never sleep well. So I went crazy, logged on here and decided to see if I could get a CPAP with a 4 year old prescription. I'll be darned, you can. Figured I should get an auto machine since my sleep doc just put "start at 6" for the pressure on the prescription.
Anyway, now to the geek part. I set the S9 to a range of 4-20 and let er rip. love all the data that thing spits out. Had 8 apneas and 4 hypopneas according to the data. Also registerd a central apnea. AHI was 2.1. The S9 kept the pressure at a min of 10 and most of the time at 14 to 15. I'm using a full face mask because of the whole lumberjack thing. Got the same results on the second night (last night). Leaks were minimal and the snore index seemed low. My wife thought I had died because she walked by the guest bedroom where I sleep and didn't here me sawing logs.
So, the data indicate to me that I may be worse than that sleep study lead the doc to believe 4 years ago. I would like to characterize just how bad just to satisfy my curiosity. Can I set the pressure to 4, turn off the auto feature and see what the S9 records for events? I'm thinking this might capture how bad I was without the CPAP.
I also got an oximeter to see if my O2 sat goes haywire without the CPAP.
I know I should go back to the doc, but I like this geeky analysis stuff. I don't see any danger to me personally because I've spent 45 years sleeping like crap. Also spent 20 years sucking on positive pressure oxygen in a fighter jet. Not sure there is any real danger here experimenting with myself.
So, that's that. Would appreciate any inputs on the self sleep test outlined above.
And thanks for this site. I would not have gotten a CPAP on my own without the advice I found here. Of course, there are those that would say I shouldn't get a CPAP on my own. Not sure who's right but I'm having a blast with this stuff.
Tom
RE: Another FNG - SuperSleeper - 03-01-2012
Hi Tom, welcome!
I'd say you're a pretty smart cookie... that sounds like an excellent idea to me (keep in mind that I'm not a sleep doctor, however).
I will say that at 4 cmH2O of pressure, it's not going to produce an absolutely accurate view of what your AHI would be like without CPAP, because even at 4.0, there is slightly more positive airway pressure than simply breathing in at normal atmospheric pressures. But it should give a pretty good approximation.
But heck, yeah, that sounds like a good test to me. Anyone else have thoughts on this?
Now, my caveat and disclaimer: if you die in the night due to complications resulting from not using your CPAP at correct pressures, I disavow giving you any sort of medical advice and always suggest that before doing any pressure change you consult with your doctor.
If you're still alive after trying this, please post back the results here in this thread and let us know what you found out. It could be VERY interesting!
RE: Another FNG - tomhole - 03-01-2012
I'm traveling right now but I made an assumption that the min pressure is 4 on the S9. Perhaps it is lower. I'll have to check that tomorrow night (or if someone finds out sooner, let us know).
RE: Another FNG - JudgeMental - 03-01-2012
Hi Tom and welcome.
I'm with Supersleeper on the pressure of 4 thing. Its very little pressure thats not go to be of any real value as far as I can see, as far as trying to determine how many apneas you might have with no positive pressure. Of course, it sounds like you are going to become an expert CPAP analist, so give it a go. Then, in my opinion, for the sake of producing beneficial CPAP therapy, you just might as well set the min. pressure up around your (most of the time figure)or 90-95% number of 14, and leave the top at 20. The top figure is pretty much meaningless. The bottom number is the least amount of pressure necessary to stop the most of the apneas.
Again welcome and keep us advised on your therapy.
RE: Another FNG - SuperSleeper - 03-01-2012
(03-01-2012, 09:03 PM)tomhole Wrote: I'm traveling right now but I made an assumption that the min pressure is 4 on the S9. Perhaps it is lower. I'll have to check that tomorrow night (or if someone finds out sooner, let us know).
Yes, S9 AutoSet minimum pressure is 4.0 cmH2O. As far as I know most every standard and auto CPAP is going to have a pressure range that is configurable within a range of 4.0 to 20.0.
Some machines go higher than 20, ie, a Bilevel positive airway pressure machine (abbreviated BPAP or VPAP).
RE: Another FNG - greatunclebill - 03-01-2012
welcome to the forum and thank you for your service from an old retired (1990) usaf msgt. i agree with what has been said plus you should get a sleep study to be sure after playing around. under tricare prime there is no co-pay for diagnostics like lab and xray and mri. sleep study also falls within this. there is no copay for sleep study. additionally, trips to the sleep doc do not require prior approval referral so you can make your own appointment with a network sleep doc. sometimes the docs want a referral from your pmimary doc anyways.
RE: Another FNG - tomhole - 03-01-2012
(03-01-2012, 09:25 PM)greatunclebill Wrote: welcome to the forum and thank you for your service from an old retired (1990) usaf msgt. i agree with what has been said plus you should get a sleep study to be sure after playing around. under tricare prime there is no co-pay for diagnostics like lab and xray and mri. sleep study also falls within this. there is no copay for sleep study. additionally, trips to the sleep doc do not require prior approval referral so you can make your own appointment with a network sleep doc. sometimes the docs want a referral from your pmimary doc anyways.
Thank you for this info. To be honest, I haven't been to a doc since I retired in 2008. Might be time to track one down.