Please help me understand

Hi all,
I don't know if its my fibromyalgia, being in menopause, having ADD or what, but I'm having MAJOR thinking problems these days. I think there are just vast areas of my brain that are totally nonfunctioning. I also have major problems with reading and comprehension, so I'm really in bad cognitive shape.
I've been trying to deal with understanding APAP pressures, indices, leak rates, so that I can better know what pressures to be at, etc., but my brain is not cooperating.
So.....can you please give me a grade-school level explanation of what it means to have a low pressure setting and a high one? Say things like "Okay.....you go to sleep and your throat starts to close off.......and then the machine does this......until you start breathing better, and then this happens......"
And what exactly happens when I start breathing out of my mouth......which leads to a high leak rate, but an acceptable AHI?
When people say its best to have a narrow margin between low and high pressures........why? When I have a certain number (off my machine's LED), for HI, does that just tell me that it happened a certain number of times an hour, but not how long it lasted?
I'm really sorry that I'm so stupid here. Its becoming really disconcerting not to be able to think clearly.
Just try to explain things to me in ridiculously simple terms. I really appreciate it!

I will let one of the forum veterans explain the ends and outs of cpap but you write a good post and ask good questions so I don't put much stock in your claim to be simple minded.

Oh I can relate. That is the very reason I was diagnosed with sleep apnea, my brain was not working and I realized that. I told my doctor, "I am not this stupid, what is going on?"

So let's see if I can start the explanation and others will surely help too.

When you have your pressure set to a range on an APAP the machine can tell what pressure you need to prevent the apneas. It will adjust to your needs as you sleep.
If you open your mouth and do not have a full face mask, you are negating your therapy and the APAP cannot prevent your apneas. It may not even record the apneas that are occuring because the way I understand it works it relies on the flow limitation to determine the apneas.
When your throat begins to close and restricts the air flow the APAP increases pressure to prevent the apnea from happening. If you have your mouth open, the flow just flows out and it shows a high leak rate, but a low AHI.

If I am incorrect in my understanding, please someone come on and correct this and educate me as well.

I hope this helps some.

Karen

I'll talk to the small range question

For me, my AHI in response to pressures is like a series of hills and valleys. Some points the response is good... and I'm in a valley with my AHI (low) and some it's bad... and I'm on a hilltop (some of which are larger than others).

What a small range allows me to do is to take the downward slope of one hill, and cut the pressure off before it gets to the next big slope going upwards.

Country4ever wrote: So.....can you please give me a grade-school level explanation of what it means to have a low pressure setting and a high one? Say things like "Okay.....you go to sleep and your throat starts to close off.......and then the machine does this......until you start breathing better, and then this happens......"

When you use a automatic machine, you set a low pressure and and a high pressure.
That is telling the machine: OK, except for the ramp, this is the lowest you ever go.
The machine chugs along at this low pressure as long as it finds no reason to raise it.
Then your breathing changes, and the machine raises the pressure.
It will raise the pressure till it finds your breathing is OK again - or till it reached the top of the range.
After some time of stable breathing it will start dropping the pressure, and will drop it all the way to the lower pressure - if no breathing disturbances occur.
Ramp (which you didn't ask about...) is when you tell the machine: "This low pressure I just gave you is too much for me to handle when I'm awake. You start out here (much lower), and raise it gradually to the bottom of the range - and meanwhile (hopefully) I'll fall asleep."

And what exactly happens when I start breathing out of my mouth......which leads to a high leak rate, but an acceptable AHI?

With your mouth open, the pressurized air does not push against the obstruction, instead it pours out of you mouth. The machine doesn't realize you may be having an obstruction - because the air is still flowing smoothly - just not in the right direction. And since the machine doesn't realize something is obstructing the flow, the AHI looks good.

When people say its best to have a narrow margin between low and high pressures........why?

When you have a broad range (or magin) the machine may do a lot of up and down roaming within that range (or margin). These pressure changes disturb the sleep of some people.

O.

Thanks everyone,
This is helping!
Track.....thanks for the compliment. But that seems to be a "problem" I have. I can sound good explaining my simple-mindedness and then it looks like I'm doing fine cognitively......but really am pretty limited in what I can think about. But thanks!
Okay.....so there can be obstruction in two places.......either in the naso-pharynx area, or the lower throat area. When the machine pushes air through my nose (I use a nasal pillow), if the obstruction is higher up, it very well could be opening up the obstruction......but if my mouth is open, it might just be easier for the air to come out there?? And if the obstruction is the lower throat....then the machine happily goes along pushing air in and out of my mouth, (but not ventilating me). Is this right?
Shouldn't the machine sense that there's too much going out of the mouth (and doesn't feel enough lung-resistance), and count that as AHI (or is that asking too much of the machine? )

Does anyone know what is the average range of pressure that a "normal" person breaths at at night? Would that be around the 4cm range?
Maybe I'm being too anal about my pressures. I never had a titration study. I refused to. I was lucky to just get through the sleep study. Fortunately, the doc let me have a machine without the titration study, and set the pressures at 4 and 8. I guess I wanted to try to feel even better than I was feeling, so started playing around with the numbers.
Even though I just went from the previous settings to 4.4/8.2, I began having more leaks and higher AHIs. Could a .2-.4 cm increase be causing that?

Okay.....so if my high pressure is at 8.2 and that's not enough to open things up, it will just stay at 8.2, but will it register as a hypopnea episode?

I understsand how setting the limits widely could cause alot of wake-ups. But wouldn't setting the upper limit too low also cause wake-ups?

If I'm fine at the lower pressure for while I'm still awake, is there any reason to turn the settling function back on?

Unfortunately, I don't have the software, so I'm going by the LED readout thing each morning. By looking at that data (LED), how would I judge if I needed to go up on the lower number, or the higher number?
For example, right now, my AHIs are under 5, but I'm spending 4-5 nights a week at my 8.2 pressure. Does that mean I should go up on the upper limit, or is there something about raising the lower limit that would help more than raising the upper pressure?

I'm getting confused again, so I'll stop. I really do appreciate everyone's help!

Country4ever wrote: Shouldn't the machine sense that there's too much going out of the mouth (and doesn't feel enough lung-resistance), and count that as AHI (or is that asking too much of the machine? )

.....

Even though I just went from the previous settings to 4.4/8.2, I began having more leaks and higher AHIs. Could a .2-.4 cm increase be causing that?

Okay.....so if my high pressure is at 8.2 and that's not enough to open things up, it will just stay at 8.2, but will it register as a hypopnea episode?

I understsand how setting the limits widely could cause alot of wake-ups. But wouldn't setting the upper limit too low also cause wake-ups?

If I'm fine at the lower pressure for while I'm still awake, is there any reason to turn the settling function back on?

Good morning, Country!

I'll add in my 2 cents worth (after inflation)....for a few of your questions:

1. I doubt that the machine can figure out that you've got air flowing out of your mouth -- it's not intelligent enough It only knows that you've got bigger leaks.

2. With the same mask, you'll generally have higher leaks at higher pressures. There are varying opinions on how much leaks matter. The sleep techs tell me that leaks don't matter until they are "large leaks" because the machine can adjust for smaller ones. The general rule of thumb I was given is that a leak rate (on Respironics) below 50 is fine, around 70-80 is not good except occasionally and when the machine classifies a leak as a "large leak" which seems to be over 90 or 100, then it ceases to count AHI's because it really can't detect them. I won't swear to the exact numbers!

3. Setting the upper limit too low could result in a higher AHI since not all events would be "fixed"

4. I gather that the "settling" or "ramp" function is for comfort so I would assume that it's not necessary if you're fine with the starting pressure. However if others have a different opinion, I'd go by that.

I'd also like to add that you needn't worry about brain fog and thinking that people will think your questions are too simple. I had brain fog for over 10 years before finding out I needed CPAP. I always felt so stupid yet others didn't see me that way. We notice it ourselves more. And, I truly believe that there is no such thing as a stupid question ... well, I probably shouldn't say that ... either Snoredog, Goofproof or Wulfman will probably come up with something just to prove me wrong

Mindy

Country4ever,

Did you have a titrated (prescribed) pressure?

If you did....have you set your machine in CPAP mode and tried it at that pressure?

What pressure range is your machine set to?

Using an APAP/Auto in a range of pressures without software is a recipe for failure, in my opinion. At best, it'll take longer to find your best pressure than using single-pressure and adjusting after a few nights data is collected. If you're mouth-lealing with that Swift, it'll mess up the pressure settings. You also don't know how many events you're having at the lower pressures before it gets to a pressure that'll take care of most of them. And, while you're having those events, your blood is not getting enough oxygen and your "brain fog" will take a lot longer to go away.

If you HAVE a titrated pressure, you need to try your therapy AT that pressure until it can be proved that it is NOT correct. Sometimes, it may only be off a few points from what was prescribed......unless you had MY sleep doctor.

Den

Country4ever wrote:Thanks everyone,
This is helping!
Okay.....so there can be obstruction in two places.......either in the naso-pharynx area, or the lower throat area. When the machine pushes air through my nose (I use a nasal pillow), if the obstruction is higher up, it very well could be opening up the obstruction......but if my mouth is open, it might just be easier for the air to come out there?? And if the obstruction is the lower throat....then the machine happily goes along pushing air in and out of my mouth, (but not ventilating me). Is this right?

Yes

Shouldn't the machine sense that there's too much going out of the mouth (and doesn't feel enough lung-resistance), and count that as AHI (or is that asking too much of the machine? )

The machines response to "not enough resistance" is "oops, here's a leak, I'll raise the pressure" and it does.

Does anyone know what is the average range of pressure that a "normal" person breaths at at night? Would that be around the 4cm range?

Normal people breathe whatever air pressure there is in the latitude they're staying at. When they go higher that they're used to, their lungs and brain need some time to acclimatize = to learn to breathe in a way that gives their body the oxygen it needs.

Okay.....so if my high pressure is at 8.2 and that's not enough to open things up, it will just stay at 8.2, but will it register as a hypopnea episode?

It the high pressure is too low you'll have more events - apneas or hypopneas.

I understand how setting the limits widely could cause alot of wake-ups. But wouldn't setting the upper limit too low also cause wake-ups?

Of course - you'll have more events (a higher AHI) and your sleep will be less refreshing.

If I'm fine at the lower pressure for while I'm still awake, is there any reason to turn the settling function back on?

None at all.

Unfortunately, I don't have the software, so I'm going by the LED readout thing each morning. By looking at that data (LED), how would I judge if I needed to go up on the lower number, or the higher number?
For example, right now, my AHIs are under 5, but I'm spending 4-5 nights a week at my 8.2 pressure. Does that mean I should go up on the upper limit, or is there something about raising the lower limit that would help more than raising the upper pressure?

By looking at the LED info you only know the you spent 90% of your time at 8.2 or below that -- if the machine is in auto mode. If you feel refreshed, fine. If not I'ld start raising the bottom gradually. If your AHI gets better, then you'll know you're getting too many events at lower pressures. If you raise the bottom pressure, and get close to the top, and you AHI doesn't get any better, you'll know you need to raise the top.
pressure - how much depends on how you feel.

And we've all had to plow through brain fog - which affects our ability to gather in new information. We need to put new information into short term memory before we can process it further, and with short term memory messed up by OSA the new data feels overwhelming and ungraspable. Don't worry, just take it one bit at a time.

O.

Thanks everyone,
You're being really kind. I've been trying to judge if my settings are good or not by how I feel during the day. But with fibromyalgia, its not so clear cut. My energy has been MUCH better with using APAP, but my cognitive problems seem to be worse. Maybe I'm just awake enough now to realize how bad my brain is!!
I guess I have this incorrect notion that apneas/hypopneas don't happen around 4-5cm pressure.....but I guess that's not so. I haven't been taking my lower pressure very seriously.......thinking its fairly useless, and just a way to gently get to the higher pressures.
I also think I'm trying to fine-tune things too much. My numbers from the software at the docs last October were really good, spending 90% of my night at 7.6cm. My 95th centile leak was .29 l/sec. My AHI was 3.3 events per hour.
But since then, my LED numbers have not been as good. But they still aren't bad. I think I just wanted to experiment and see if I could feel even better. Maybe I should just go back to the original settings? I sort of feel silly........it seems like everyone else has pressures so much higher than mine. But I guess if lower pressures are all I need.....then that's where I need to be.
And I have to admit, I'm really nervous about the doc seeing that I've been playing around with it........especially since I really don't know what I'm doing! But at least I've gone very slowly with the changes. And 4.6 and 8.2 aren't much different than the original settings of 4/8.
I never did have a titration study.......so the doc just picked 4 and 8 out of the air.
I'm really claustaphobic and am fairly sure I wouldn't do well with a full face mask........so I'm trying to avoid that. Is it possible that my numbers can look good, but I'm leaking enough to make all this treatment totally useless? Or would it at least show up on the leak data? Is it possible that if I had a full face mask, the numbers would look really similar, but I would feel tons better??
I'm sorry if I'm repeating myself.
And I definitely appreciate the patience you're all showing me.
I read the words, and they just don't soak in. Its like there's a pretty big disconnect somewhere.

Sounds like you've spent a good deal of time in the vacinity of 8 cm., so, I'd suggest setting it in CPAP mode at a pressure of 8 and see how the numbers look. You could try an EPR setting of 1 or 2 so you can check out how that feels.

Den

Country, I'm concerned that you're confusing the top and bottom range for the ramp (or settling) and the top and bottom range for therapy pressure.

"Easing you into higher pressure" is the role of the ramp.

If your 90% pressure with the software was 7.6 then I'ld set the therapy pressure range at 6-8 and stick to it for a week or two, noting the AHI daily.

Is it possible that my numbers can look good, but I'm leaking enough to make all this treatment totally useless? Or would it at least show up on the leak data? Is it possible that if I had a full face mask, the numbers would look really similar, but I would feel tons better??

The answer is a qualified - very qualified - yes to both. "totaly useless" and "tons better" are extreme terms. If you mouthleak all night long, then your therapy is useless all night long. And if you mouthleak badly, switching to a full face mask may help you feel better.

Have you checked the other ways of controling mask leaks?

O,

Thanks Wulfman and Oz.
I understand the difference between ramp/settling and my lower pressure. I guess since everyone else seems to need higher pressures, that low of a pressure (4) seems like its probably useless. Am I making any sense? Or does that pressure of 4 mean that as soon as the machine senses an obstruction, it only starts at 4 to correct it? Ah! I think I'm starting to understand........ Do I have this right?: It pushes air into me at 4cm all the time. But as soon as I start having trouble breathing, then it starts increasing the pressure from there. The unfortunate part of having it set at 4 is that I might have a sudden big obstruction, and since the machine only goes up in small increments, it might take too long to really deal with the obstruction. Am I right?
Oh man do I feel stupid. This reminds me of a few years ago when I insisted on having an educational psychologist test me for some type of learning problem (since I have so much trouble with reading and comprehension). I did fine for the most part, but there was this one little test that I just couldn't understand, no matter what! Anyhow.......that's what this reminds me of!
If I did try the CPAP mode set at 8.....and an EPR of something lower, and I woke up in the night, would that high pressure keep me from going back to sleep?
When I see my sleep doc in January and he downloads/uploads all this info, will he see all the crazy adjustments I've made??

I think you're getting the picture, now.

If you start at 4 and it takes a pressure of 7 or 8 to clear an event, it can take a bit of time for it to get there. And, if you happen to be one (like me) that pressure changes disturb sleep, you'll either be waking up or won't sleep as well.
I doubt seriously whether your doctor would be able to tell whether your "adjustments" had been made. In any case, just remember that your doctor works for YOU. Whatever you do that results in better treatment, shouldn't make a damn bit of difference to your doctor. He/she should be happy for you. Because, it's YOUR therapy.

EPR is the "breathing relief" setting. It drops the pressure during your exhale to make it easier to breathe. A setting of 1 offers the least relief and the setting of 3 the most relief.

You won't know the answers until you try the options.

Den

Suppose you were at 4 and needed 8 to clear an event., I was told the machine will only go up 3 in response to an event. If you are at 4 you will only reach 7 and the even won't be cleared. Therefore you need a tighter range. You need to find a valid pressure and looking on the LED panel won't give it to you.

Until you get the software and can download the daily graphs of your pressures, leaks, and events, or until you do a titration in the lab or get your doc to look at the detailed graphs over a week's worth of APAP data with a larger range, you are just playing a guessing game and could be way off in your range versus what treatment you really need.

Since you don't seem to want to do the titration in the lab (hmm - that sounds very familiar as I never did), you need to buy the software and get some of the detailed graphs posted here on the forum so some of the experts here can give you some ideas on how to proceed with your treatment. This is a case where a picture (graph) is well worth 1000 words.