Sleep Wake Junk Mystery

Woke up after about 3 and a half hours last night and realised that I wasn't getting back to sleep in a hurry.

I saw this as a very good time for an experiment. I got out my book, put the mask and machine back on and read for just under 2 hours. When I looked at the SH data this morning there were over 40 events during this time with 70% being registered as OAs (30% hypopneas) so you can imagine how that pushed my AHI numbers up. I did not fall asleep at all and every now and then my tongue detached briefly from the roof of my mouth giving a pop that I could feel through the tubing of my Dreamwear mask. Pressure went up to the maximum of 14 but I cant understand why unless lying on your back does this to you. Was this little pop what gave the OA readings? I don't remember having that many of them.

I am wondering if the F&P Icon does that good a job of interpreting events as I now have a continuous history of recorded events even though I am awake.

No large leaks, I was under 14cm for 90% of the time.

Can anyone offer an explanation? Is the machine imagining that I am having events.

Will I get rid of this when I change to the Resmed S9? At least it will far more information than the Icon.

Hi - well, the machine doesn't 'know' if you're awake or not, but the fact is that your breathing pattern is different when sleeping so the machine doesn't respond the same way at all. In other words you can't (or shouldn't try to) get any kind of valid result from such an experiment because it won't be valid, and I imagine the teeth/tongue business, while maybe good practice for you, wouldn't have the same effect either.

And you may be absolutely correct about not having slept at all, but patients routinely swear they did not sleep during lab studies when in fact they did, if only for short periods of time... happens every day.

The fact you were on your back (I assume, if reading, a position that would normally provoke more apneas than otherwise, means that if you did snooze at all, a few events might have been recorded, but you'll never know for sure what happened there. And I can't see where a different machine would make a diff. Sleep-wake junk is about transitioning to or from sleep, and you can't manufacture or eliminate it artificially.

Holden4th wrote:Woke up after about 3 and a half hours last night and realised that I wasn't getting back to sleep in a hurry.

I saw this as a very good time for an experiment. I got out my book, put the mask and machine back on and read for just under 2 hours. When I looked at the SH data this morning there were over 40 events during this time with 70% being registered as OAs (30% hypopneas) so you can imagine how that pushed my AHI numbers up. I did not fall asleep

What your experiment demonstrates is that there is a huge difference between the way normal wake breathing and normal sleep breathing. And that our machines are not capable of distinguishing between when we are awake and when we are asleep. And that our machines will mis-score normal wake breathing patterns as sleep disordered breathing events.

Even when we don't realize it, we consciously control our wake breathing in ways that we don't control our sleep breathing. When awake, we routinely sigh, hold our breath momentarily when concentrating (we often don't realize it), take a deep breath now and then and then breath shallowly for the next following breaths. We swallow without being aware of it, which can "block" the airway momentarily. In other words, normal wake breathing, even when we're resting, is a lot more "ragged" looking than sleep breathing. And all that raggedness can be interpreted by the machine (which thinks you are asleep simply because you are using it) as apneas, both OAs and CAs, and Hs. And add to this the fact that the CPAP itself can alter our wake breathing patterns simply because we're aware of the air being blown down our upper airway when we're awake. If the brain feels like too much air is coming into the lungs when we're awake and we're not in a panic, it may voluntarily decide to skip a couple of breaths to make sure the CO2 level doesn't get too low, for example.

So, yes, if you use the machine for 2 hours while reading in bed, it would NOT be unusual to have a ton of events that run together in a 2-hour long "cluster".

And yes, the machine will respond to all those OAs and Hs by raising the pressure. And certain kinds of sniffles or clearing the throat noises can be interpreted by the machine as either snores or flow limitations, both of which will cause the machine to raise the pressure. So it's also no surprise that the machine maxed out during your two hour experiment.
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I am wondering if the F&P Icon does that good a job of interpreting events as I now have a continuous history of recorded events even though I am awake.

...

Will I get rid of this when I change to the Resmed S9? At least it will far more information than the Icon.

The Icon and the S9 are programmed to analyze sleep breathing. When you are asleep, both machines are pretty much looking for the same thing: Sudden decreases in flow volume that last at least 10 seconds (to score an apnea or H) and certain kinds of raggedness in the shape of the flow rate curve that indicate snoring is going on and other kinds of raggedness in the shape of flow rate curve that indicate there is a flow restriction.

My best guess is that if you repeat this experiment with the Resmed S9, you will still see a ton of near continuous events when you are awake for 2 hours reading in bed. My guess is that the Resmed will also max out pressure if its run in AutoSet mode.

But you are correct, the S9 does provide more data than your Icon. If the Icon recorded the actual flow rate so that you could see every breath you took during the 2-hour experiment, you would be able to see the visual difference between normal wake breathing and normal sleep breathing.

Holden4th wrote:I did not fall asleep at all and every now and then my tongue detached briefly from the roof of my mouth giving a pop that I could feel through the tubing of my Dreamwear mask. Pressure went up to the maximum of 14 but I cant understand why unless lying on your back does this to you. Was this little pop what gave the OA readings?

No, I don't think those pops were why the machine was recording a whole slew of OAs. (See my previous post)

My guess is that those pops were most likely the result of pressurized air suddenly entering your oral cavity when your tongue was no longer blocking the oral cavity off from the upper airway. The machine had to temporarily push a bit more air into your upper airway to compensate for the air that went into your mouth rather than down your upper airway.

1 for Robysue.
My awake breathing is so irregular that a recent 20 minute MRA procedure took almost 60 minutes while the technician struggled to synchronize the scanning with my breathing. Needless to say, my claustrophobia didn't help all that much.

Thank you folks, that has certainly added to my knowledge base of what happens when both awake and asleep. I now know I can ignore those early few minutes after replacing the mask.