Minimum pressure -- trying to understand the algorithm

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Pugsy
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Re: Minimum pressure -- trying to understand the algorithm

Post by Pugsy » Tue Oct 21, 2014 4:17 pm

Wulfman... wrote:Or, maybe a straight pressure........
I was wondering how long it would be until you said that.

It did also cross my mind but I wanted to hear the answer to "why the wake ups" first and then maybe get a feel for what was going on before giving my usual...with more minimum pressure the maximum may not go so high...speech.

She's so new to this therapy that I really didn't want to suggest big changes unless big changes were warranted and the wake ups could be from a dog or something. and the AHI doesn't support a need for a big change at this point anyway.

But yes...I am thinking more minimum (maybe 9ish) and see what happens...if and when she feels up to experimenting further and depending on the answer to "why the wake ups".

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Re: Minimum pressure -- trying to understand the algorithm

Post by palerider » Tue Oct 21, 2014 4:18 pm

Wulfman... wrote:
palerider wrote:
Wulfman... wrote:Or, maybe a straight pressure........
ones one figures out what it should be.

you must *love* the cpap-check feature of the 460/560.
I have no idea what you're referring to, but I'd suggest a straight pressure of about 9 or 10 cm.
it's an optional mode of the 460/560, where it runs in auto mode for a period, till it finds what it thinks is the best pressure, then it goes into cpap mode, and then re-evaluates periodically, but it's mostly fixed pressure.

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Re: Minimum pressure -- trying to understand the algorithm

Post by palerider » Tue Oct 21, 2014 4:20 pm

Pugsy wrote:
Wulfman... wrote:Or, maybe a straight pressure........
I was wondering how long it would be until you said that.
it's good to have things you can count on...

if Den starts advocating auto setting, I'd be a bit weirded out!

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Re: Minimum pressure -- trying to understand the algorithm

Post by Pugsy » Tue Oct 21, 2014 4:23 pm

palerider wrote:if Den starts advocating auto setting, I'd be a bit weirded out!
If Den starts doing that I am making a road trip to Montana to check on him because I know something bad happened and he needs me.

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Re: Minimum pressure -- trying to understand the algorithm

Post by palerider » Tue Oct 21, 2014 4:24 pm

Pugsy wrote:
palerider wrote:if Den starts advocating auto setting, I'd be a bit weirded out!
If Den starts doing that I am making a road trip to Montana to check on him because I know something bad happened and he needs me.
he should be glad to know that there's people that care about him. perhaps you can hitch a ride with hubby?

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Re: Minimum pressure -- trying to understand the algorithm

Post by cathyf » Tue Oct 21, 2014 4:28 pm

Pugsy wrote:How come the wake ups? Any idea?
Not a lot of clues... Maybe it's menopause -- yes, sleep disturbances are one of the more crippling effects. Maybe it's habit -- the last couple of nights when I have woken up -- at least later in the night -- I've been able to stay in bed and just be annoyed at being awake and eventually go back to sleep, because my back teeth have NOT been floating. But before the cpap I got up a LOT to go potty. It's been that way for a LONG time -- at least 20 years -- because when I found out 20 years ago that in order to take basal body temps you need to have been asleep for at least 4 straight hours I was SHOCKED. I think I get 4 hours in a row a couple of times per year. Looking over the nights, my best night was Saturday night. I was doing laundry and didn't get into bed until 12:30 and slept until 6:15.

I didn't put my events on there. I am not having hardly any -- AHI is 0.36 -- and a lot of them are when I am awake. Or, to pick on Frank again, I've got hypopneas that just show up out of the blue, just one, and then the night goes along like nothing happened.

My machine is set at 7-20, and like I said, it doesn't seem to have any trouble picking high pressures and just staying there. Given what y'all are saying about trying to get settings where the machine will behave, I'm getting the feeling that if I were on a machine with the technology from 20 years ago it would not be working nearly so well...

One thing... I have an enlarged thyroid, and a couple of months ago I noticed that at the very end of an exhale I would get a short little "squeak". It's totally unpredictable and I haven't figured out how to cause it to happen, I just notice that it's happening. It does seem to happen more when I am on my left side, which puts the right lobe of my thyroid (the larger one) on the top of a thyroid-windpipe sandwich. I have not heard/felt one at all since I have been on the cpap. It's possible that I have flow limitations all of the time, awake and asleep. Certainly the flow limitation graph is not recognizably distinct when I am awake.

I do sing in 2 community choruses and a church choir, and can sing long phrases and stay on pitch, so it's not SO limited.

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Re: Minimum pressure -- trying to understand the algorithm

Post by palerider » Tue Oct 21, 2014 4:38 pm

cathyf wrote:Or, to pick on Frank again, I've got hypopneas that just show up out of the blue, just one, and then the night goes along like nothing happened.
I'd be willing to bet that all of your apneas, few though they are, are preceeded by precursors, which are snores and flow limitations, (after seeing what you posted).

so it's likely that none of your apneas are 'sudden' or out of the blue

flow limitations aren snores are precursors, which is why the machine ramps up pressure aggressively when they happen, in attempt to head off the apneas in the first place, though, of course, it's not perfect at that, but it does try.

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Re: Minimum pressure -- trying to understand the algorithm

Post by Wulfman... » Tue Oct 21, 2014 4:43 pm

Pugsy wrote:
palerider wrote:if Den starts advocating auto setting, I'd be a bit weirded out!
If Den starts doing that I am making a road trip to Montana to check on him because I know something bad happened and he needs me.
If you go to Montana looking for me, you won't find me THERE. You don't have to go that far North. Just a little ways Southeast of Yellowstone National Park (as the crow flies).

Just to be clear, I'm not AGAINST a range of pressures......IF it fits the person's breathing and events patterns. Having pressures bounce all over the place and disrupting sleep all night isn't "productive" if it's not preventing "real" events IMO.
And, just because a machine will vary pressures and chase events all night long doesn't make the Auto mode a "better" option. It's just AN option.


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Re: Minimum pressure -- trying to understand the algorithm

Post by palerider » Tue Oct 21, 2014 4:51 pm

Wulfman... wrote:Just to be clear, I'm not AGAINST a range of pressures......IF it fits the person's breathing and events patterns. Having pressures bounce all over the place and disrupting sleep all night isn't "productive" if it's not preventing "real" events IMO.
And, just because a machine will vary pressures and chase events all night long doesn't make the Auto mode a "better" option. It's just AN option.
fwiw, I agree with you. ... whatever works for the individual.

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Re: Minimum pressure -- trying to understand the algorithm

Post by Wulfman... » Tue Oct 21, 2014 4:56 pm

cathyf wrote:
Pugsy wrote:How come the wake ups? Any idea?
Not a lot of clues... Maybe it's menopause -- yes, sleep disturbances are one of the more crippling effects. Maybe it's habit -- the last couple of nights when I have woken up -- at least later in the night -- I've been able to stay in bed and just be annoyed at being awake and eventually go back to sleep, because my back teeth have NOT been floating. But before the cpap I got up a LOT to go potty. It's been that way for a LONG time -- at least 20 years -- because when I found out 20 years ago that in order to take basal body temps you need to have been asleep for at least 4 straight hours I was SHOCKED. I think I get 4 hours in a row a couple of times per year. Looking over the nights, my best night was Saturday night. I was doing laundry and didn't get into bed until 12:30 and slept until 6:15.

I didn't put my events on there. I am not having hardly any -- AHI is 0.36 -- and a lot of them are when I am awake. Or, to pick on Frank again, I've got hypopneas that just show up out of the blue, just one, and then the night goes along like nothing happened.

My machine is set at 7-20, and like I said, it doesn't seem to have any trouble picking high pressures and just staying there. Given what y'all are saying about trying to get settings where the machine will behave, I'm getting the feeling that if I were on a machine with the technology from 20 years ago it would not be working nearly so well...

One thing... I have an enlarged thyroid, and a couple of months ago I noticed that at the very end of an exhale I would get a short little "squeak". It's totally unpredictable and I haven't figured out how to cause it to happen, I just notice that it's happening. It does seem to happen more when I am on my left side, which puts the right lobe of my thyroid (the larger one) on the top of a thyroid-windpipe sandwich. I have not heard/felt one at all since I have been on the cpap. It's possible that I have flow limitations all of the time, awake and asleep. Certainly the flow limitation graph is not recognizably distinct when I am awake.

I do sing in 2 community choruses and a church choir, and can sing long phrases and stay on pitch, so it's not SO limited.
If the enlarged thyroid is in fact contributing to the Flow Limitations, then (in my opinion) you need to make the machine ignore them. Yep......straight pressure. Sure, they may be preceding the Apneas, too, but that's ALOT of Flow Limitations for the machine to chase for only a few apneas.

If you're willing to TRY straight pressure, I'd suggest starting with a pressure setting of 9 minimum pressure and 9 maximum pressure in APAP mode.
Depending on whether or not you "need" Ramp, that's up to you. Some people start without it and some people feel they need to use it for awhile. Maybe work upwards with the starting Ramp pressure until you feel you can eliminate it.


Den

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Re: Minimum pressure -- trying to understand the algorithm

Post by Wulfman... » Tue Oct 21, 2014 5:00 pm

Pugsy wrote:
Wulfman... wrote:Or, maybe a straight pressure........
I was wondering how long it would be until you said that.

It did also cross my mind but I wanted to hear the answer to "why the wake ups" first and then maybe get a feel for what was going on before giving my usual...with more minimum pressure the maximum may not go so high...speech.

She's so new to this therapy that I really didn't want to suggest big changes unless big changes were warranted and the wake ups could be from a dog or something. and the AHI doesn't support a need for a big change at this point anyway.

But yes...I am thinking more minimum (maybe 9ish) and see what happens...if and when she feels up to experimenting further and depending on the answer to "why the wake ups".
I'm so glad to know that "you're learning"........

(and that I'm pretty predictable in some of these situations)


Den

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Re: Minimum pressure -- trying to understand the algorithm

Post by Pugsy » Tue Oct 21, 2014 5:03 pm

The enlarged thyroid could account for those flow limitations (or maybe part of them). It could be pressing on the airway a bit.
We had another forum member not long ago that had a similar situation but her FLs were much, much worse than yours.

Do you sleep in any certain position or move around a lot? Spend much time on your back?

Having gone through the menopause thing...it totally wrecks any chance of good sleep...nasty little thing that mother nature gave us.

You know it's entirely possible that the pressure changes you are seeing are being a disruptive factor to your sleep quality...maybe disturbing you in some fashion. Hard to tell with the other stuff going on but you might want to consider limiting the range or (whisper...go to cpap mode if you want to) and see if it helps the sleep quality any better.
At this point the AHI is fine...but your sleep isn't. How much of it is maybe the flow limitations or the changing pressures...that's up for grabs but it's something to think about.

The flow limitations themselves aren't in any urgent need of additional pressure therapy as long as they aren't causing problems....but we don't have any way to know for sure if they are causing a problem or not. They are far from horrible.
If you were sleeping soundly and feeling decent I wouldn't do anything about them if it were me.

So here comes the speech about sometimes when we increase the minimum then the maximum actually drops and settles lower. That's because the machine with the minimum pressure higher is holding the airway open better so the machine doesn't have to fight to open the airway with more pressure. Might still an occasional short lived increase (like maybe supine sleeping or REM sleep) but for the most part the wild variations settle down.

Now if it is your thyroid that is the flow limitation culprit...it may be that nothing will hold it open further than it is and you just live with it like it is and then work on whatever pressure keeps your AHI low and you sleep better (hopefully).
Now it might be the menopause thing and it might just be habit.

If it were me I would probably at least try more minimum just to see if it helped the sleep quality any and maybe cut down on the flow limitations. If you were sleeping great...I wouldn't mess with it but you aren't.
No guarantees though especially if it is just habit or menopause.
The 9 ish minimum is probably what I would try...see if the maximum still wants to go where it's wanting to go and if it does...and flow limitations don't change at all...maybe limit the maximum for a while (tiny range or do cpap mode) just to see if it's the variations in pressure that is the culprit.
It may be that you just have a little dose of sleep maintenance insomnia not tied to anything related to sleep apnea and nothing we do with the machine will help much but it doesn't stop a person from trying things to see.
If we don't try...we don't know if a little change might have helped or not.

Up to you...there is no rush to do anything right this minute. Don't do anything because I said so or Den said so or whoever unless it is something you want to do and you understand what you are doing and what you are looking for.
Do be prepared to give any change some time...don't go changing things nightly. You will be chasing your tail every night if try to fix last night after the fact.

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Re: Minimum pressure -- trying to understand the algorithm

Post by cathyf » Tue Oct 21, 2014 8:46 pm

I'm thinking that since I just turned on the autostart last night I would give it another day or two before changing something else.

There is one other thing that has been happening a lot over the last year or two and did happen once on the machine, which is that I will wake up and want to sit up and lean forward. It's similar to when I had pneumonia 4 years ago, where I feel like the only way that I can catch my breath is to lean forward. (Ok, it's not like pneumonia in any way except that leaning forward seems to help.) I noted the times while it was happening and looked at the data the next day, and it was totally unremarkable compared to the other data. Unfortunately I have now forgotten which night it was -- I had not noticed the "notes" tab in Sleepyhead...

We also have the family sleep gene in my family. My dad falls asleep at the dinner table during a big loud enthusiastic family dinner, as well as dozing off and on pretty much continuously. My brother and I and two of my brother's kids have it, too, but to a lesser extent. When I was in high school and my family went to Europe, every time we got in the car my brother and I were asleep. When we drove from Paris to Amsterdam I completely slept through Belgium, for example.

I notice that the flow limitation seems to track the snoring pretty closely. And to think that my husband was totally surprised at the sleep study report that says that I snore a lot!

My untreated AHI is not high -- ApneaLink screening showed 8-11 (depending upon whether you use sleep time or test time as the divisor), while the sleep lab test showed 15. I would love to get it to where I would not wake up in the night, or at least go back to sleep right away. It is certainly better since I've been on cpap, and hopefully with a little tinkering I can get it even better.

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Re: Minimum pressure -- trying to understand the algorithm

Post by Wulfman... » Tue Oct 21, 2014 9:32 pm

As always, it's your therapy.
We just review the data and express our thoughts, opinions and potential options. Sometimes we agree and sometimes we don't or have some variations.
Please let us know how things are going.


Den

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Re: Minimum pressure -- trying to understand the algorithm

Post by cathyf » Wed Oct 22, 2014 5:34 am

So I tried a little compromise -- raised the minimum pressure to 8. Had an AHI of 0, but still had lots of awakenings. My humidifier ran out of water in the middle of the night -- that was the reason I got up at 3:30...

I think I will raise it to 9 tomorrow night. The machine doesn't seem to feel very constrained by the min pressure, so maybe it won't matter. But one data point does not a dataset make!

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