Baseline AHI analysis with CPAP (without airflow adjustments)

Hi there,
Thanks to this wonderful forum, I think I have a much better idea of how to analyze my sleep apnea issues.

I am interested now in doing 'baseline' test of what my real AHI is when I am sleeping without the CPAP trying to push any adjustments. I have doubts about the sleep lab for various reasons:

• They had me sleeping on my back all the time (I am not back sleeper), attached to various sensors, which I'm sure degraded my quality of sleep
• The room was way too cold for my comfort level

I am therefore interested in running a 'baseline AHI' test myself where I'd like to use the CPAP but not have it try and put any air pressure. My objectives are:

• Have the device track my AHI for one night
• Not try to fix my apneas, as I indicated above
• Ideally, if possible, not record this night in its database

Any thoughts on how I might go about this? My guess is item 3 is not possible as I am interested in extracting that data to OSCAR so I can't really have it both ways (i.e. take to OSCAR but not to the dream station app)

Thank you.

Yes I have tried something similar in the past.
However, CPAPs are not diagnostic machines so the closest you will get is an approximation.

It's not possible to have the machine run without pressure so you will always get some therapy pressures involved to skew the results.
The closest you can get is to turn the pressure settings as low as possible/tolerable to minimize the therapeutic skew.
The downside there is that if you have the pressure settings as low as possible you may feel a bit suffocated due to getting little "breathing relief" or PS/EPR/Flex (depends on the machine).

A reasonable compromise (if you have, say, a ResMed AutoSet) is to set EPR off (equivalent to "PS"=0) and find a low pressure that you can tolerate. If you increase EPR for comfort you will get more therapeutic skew.
Nevertheless, providing you take the results with a pinch of salt, you may get close to your objectives.
Does that make sense?

ApneaMachines wrote: ↑

Fri Feb 28, 2020 9:53 am

Yes I have tried something similar in the past.
However, CPAPs are not diagnostic machines so the closest you will get is an approximation.
<snip>
Does that make sense?

Hello ApneaMachines, thank you for your thoughts. How about I tried this (and I'm asking questions before attempting because I'm trying to maintain my real AHI tracking with the CPAP working as intended, with minimal disruption):

• Instead of my Resmed N20 mask (which fits over my nose), I use my Resmed N30, which fits under my nose
• turn the CPAP to fixed mode and minimum pressure for that night (whatever it is, maybe 4)
• I put the mask on but loosely - so that it can measure my AHI but I get some space to also breathe normally without the suffocation

Having a mask so loose that that you can breathe around it will just cause pressure leaks and the machine will become totally confused because the pressure/flow sensors won't know what's happening.
As a result, the reported events may be unreliable.

Using basic CPAP at a low pressure is a good attempt but you may find it's not comfortable. As you tweak things to make it tolerable, you will basically be adding more therapy and therefore more skew.
You are on the right lines though... keep the settings as low as you can tolerate and then take the results with a pinch of salt.
I don't remember if all events and data streams are reported in basic CPAP mode, I'd stick with AutoSet mode to ensure that the full reporting happens.

As far as the data storage is concerned, the machine doesn't know that you are experimenting and will incorporate the readings into its averages.
If you use OSCAR to look at the data, you will be able to compensate for the experimental night and.. if you wish... you will be able to delete the data in OSCAR for that night and eliminate it altogether.
By deleting that data in OSCAR you'll just end up having a night of no data and therefore a false impression of non-compliance for that one night.

ApneaMachines wrote: ↑

Fri Feb 28, 2020 10:32 am

I don't remember if all events and data streams are reported in basic CPAP mode, I'd stick with AutoSet mode to ensure that the full reporting happens.

With the Respironics machines Flow Limitation flagging is turned off in fixed cpap mode.

This smart plan of mine did not quite work. I tried experimenting with low pressure but it made me very uncomfortable which I think would defeat the purpose of my baseline test. Oh well, I wish I knew more before I did my sleep test. I was pretty much a deer in the headlights at that time. Well, I still am, but now I know I need to smile.

If you are doubting your need for CPAP, how about you set your machine wide open 4-20. If your pressure rises, it means there were breathing indicators that made it increase to ward off trouble rather than restrict you and cause feelings of suffocation. Giving it the option to increase may make it more tolerable. It doesn't give you the exact answers you seek, but can serve as a confirmation you have OSA. If having the airflow so low bothers you, that may be an indicator you need the treatment. Good luck figuring things out.

FYI in case you're not sure, machines don't know if you're awake or not when working, so if you've been 'testing' while awake results won't be valid.

DustyDoozeer wrote: ↑

Fri Feb 28, 2020 9:23 am

I am interested now in doing 'baseline' test

I am therefore interested in running a 'baseline AHI' test...

• Have the device track my AHI for one night
• Not try to fix my apneas, as I indicated above
• Ideally, if possible, not record this night in its database

Any thoughts on how I might go about this? My guess is item 3 is not possible as I am interested in extracting that data to OSCAR so I can't really have it both ways (i.e. take to OSCAR but not to the dream station app)

Thank you.

The only way is to pay for an at home test, but to what end?

All the distractions and discomforts at the sleep lab serve to reduce your sleep, leading to a lower AHI reading than what is accurate. And even if it were accurate, it does not matter, the only thing that matters is that it was bad enough to get a machine.

What matters now is that you focus on optimization of your treatment, not some number showing (at best) some vague number of "how bad was I before". That simply does not matter!

Stop looking back, start looking forward. Pull the data, post some charts, start getting better sleep.

(I wish this forum has multi-quote capabilities. If it did, I don' see the option when I respond)

palerider wrote:Stop looking back, start looking forward. Pull the data, post some charts, start getting better sleep.

Fair enough. I did - right here viewtopic/t178568/Im-trying-to-learn-ho ... 5#p1343848

kteague wrote:If you are doubting your need for CPAP, how about you set your machine wide open 4-20. If your pressure rises, it means there were breathing indicators that made it increase to ward off trouble rather than restrict you and cause feelings of suffocation

Yes, the issue I had was when I set it to low pressure and tried to sleep, the fully covered nose mask made me very uncomfortable, breathing wise. I suppose trying to baseline without the equivalent of what the sleep lab did is futile and as suggested above, I've dropped the idea.

DustyDoozeer wrote: ↑

Tue Mar 03, 2020 2:04 pm

(I wish this forum has multi-quote capabilities. If it did, I don' see the option when I respond)

palerider wrote:Stop looking back, start looking forward. Pull the data, post some charts, start getting better sleep.

Fair enough. I did - right here viewtopic/t178568/Im-trying-to-learn-ho ... 5#p1343848

if'n you find that multiple quote button, please let me know!

as to the rest, this is why it's a good idea to keep yourself contained in one thread when you first get here. it helps others keep track of what is going on with you. certainly after you've been here for "some time", which i'm carefully not defining, you can stretch out, so to speak.

not a hard and fast rule. i'm neither moderator or forum owner. just makes sense to this random guy on the internet.

DustyDoozeer wrote: ↑

Tue Mar 03, 2020 2:04 pm

(I wish this forum has multi-quote capabilities. If it did, I don' see the option when I respond)

palerider wrote:Stop looking back, start looking forward. Pull the data, post some charts, start getting better sleep.

Fair enough. I did - right here viewtopic/t178568/Im-trying-to-learn-ho ... 5#p1343848

And now, you're off the rails, instead of just working to make your therapy *better*.

CPAP is a treatment tool, it is not a diagnostic tool.
There is no way to do what you're asking with any useful degree of accuracy.

And now, you're off the rails, instead of just working to make your therapy *better*.

Quite the contrary. I am seeing improvement. Trying to understand should be supported especially in a forum that advocates owning your own therapy and using OSCAR. now if I said I am constantly tweaking things based on potentially incorrect assumptions then a rap would be understandable. Hopefully, I'll keep improving on my interpretations.

CPAP is a treatment tool, it is not a diagnostic tool.
There is no way to do what you're asking with any useful degree of accuracy.

Indeed. So it seems. It is objective commentary like this that helps me improve. Thanks.

DustyDoozeer wrote: ↑

Wed Mar 04, 2020 6:18 am

And now, you're off the rails, instead of just working to make your therapy *better*.

Quite the contrary. I am seeing improvement. Trying to understand should be supported especially in a forum that advocates owning your own therapy and using OSCAR. now if I said I am constantly tweaking things based on potentially incorrect assumptions then a rap would be understandable. Hopefully, I'll keep improving on my interpretations.

You should be infrequently tweaking things, *based on current data*, not what may or may not have happened during a sleep test, which is but a single still frame on the full length feature film of your sleep.



Does that tell you anything useful about the movie? do you understand the plot, the intrigue, the essence?

That's your sleep study.

Watch the movie, stop obsessing about a still frame (or two).