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Clear Airway definition
#11
(03-22-2012, 07:18 PM)SuperSleeper Wrote: Bill, reducing or turning off A-Flex is going to decrease AHI, generally... same thing with reducing the amount of time for ramp period. Not much, but it should help to a degree. If not possible for comfort or tolerability reasons, I understand.

Not sure if you tried this, but if your average 95% pressure is 11.0, I'd be willing to bet good money that your pressure needs go up above 12.0 at certain times during the night (on some nights), and your current upper restriction of 12.0 might be hampering you from obtaining the best possible pressure during those times to punch through a particularly stubborn event. Have you tried increasing the upper pressure limit to say, 15 or 16 for one night and seeing the effect upon overall AHI?

In any case, good idea to discuss with the doc, considering the other issues.

like i did say, i raised it to 12.5 because i bumped into 12, 3 or 4 times total since i bought it. i haven't bumped into 12.5. it seems odd to raise it for the once a month that it may go higher. maybe i'll raise it. maybe not. i'm scared of it going way up, triggered by a leak or something. i'm iffy on this.

i feel i need the a-flex, although i will play with the number on it. the ramp makes no sense because it's only 15 minutes, i'm usually not sleeping right away and i see zero events during it. it does help me adjust to the sudden 8.5. i have tried without it and don't like it. i'm getting up at night way less times and not at all lately. when i was, it worked not using the ramp when i put it back on at 3am because i was half asleep and usde to the pressure.

the original thought was ca. what's your reading on that?


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#12
Might be a good idea to see the sleep doctor, there is something is not right and beyond my understanding.
Let the Doc decide, it could be medication or other health issues not related to sleep apnea or might need different type of machine.
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#13
(03-22-2012, 07:42 PM)Netskier Wrote: Is there evidence that higher max pressures reduce central events?

Howdy, Netskier...

There is debate on that. Some believe higher pressures increase centrals... others say it has no major effect. Truth is probably somewhere in between... and it depends upon the individual, I think.

Increased pressure can reduce obstructive events, thus lower overall AHI... and sometimes increasing the pressure slightly will increase centrals to a small degree, but decrease obstructive events to a greater degree, thus having an overall effect of lowering the AHI.

As far as I know (and we've had a ton of discussion on this in the old forum) there is no solid, reliable large-group study that has proven that higher pressures lead to increased centrals, although this contention seems to be prevalent out there among some professionals... but with very little publically-available scientific proof to back up that claim.

The whole point is that since everyone is different, experimenting with pressure settings scientifically is probably one of the best ways to determine optimum pressure settings. There isn't a one-size-fits-all pressure range, and there are real limitations even when doing an overnight sleep study in a lab, which is a completely different environment than a patient's bedroom.

In addition, eventhough a machine lists central events in the data... this doesn't necessarily mean that all of those are actual centrals. The machine just determined that there is an event and that it doesn't appear to be obstructive, therefore is generally assumed to be a central event, and listed in the data as a central or "clear airway" event.

Smile
SuperSleeper
Apnea Board Administrator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.



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#14
Bill, I don't pretend to know all about the proprietary algorithms that autos use when adjusting pressure. But it is conceivable that they look at the pressure ranges in a percentage-sort-of way. Thus, the algorithm will only raise the pressure a certain percentage towards the high end, rather than looking at the raw cmH20 pressure numbers.

In other words, if you set the high-end pressure at 12, the algorithm may tell the machine to go to 80% of that pressure over a specific period of time, then 90% of that pressure during the next period of time, on up to 100% over a longer period of time. If that is the case, and you're experiencing obstructive events during the deep sleep periods that may occur later in the sleep cycle, the machine will not go higher fast enough to deal with a bad obstructive event... and will be restricted by the algorithm.

Raising the high-end pressure may expand those percentages enough to allow the pressure to raise to the higher levels faster, thus reducing the obstructive events.

Hope that made sense. Cool
SuperSleeper
Apnea Board Administrator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.



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#15
(03-22-2012, 08:19 PM)zonk Wrote: Might be a good idea to see the sleep doctor, there is something is not right and beyond my understanding.
Let the Doc decide, it could be medication or other health issues not related to sleep apnea or might need different type of machine.

absolutely. i take 4 pills in the morning and 2 at night. some of them are more than one drug combo drugs. also 2 different asthma sprays. plus i'm in a b-12w shot regimen and take vit d every other week, not the otc kind.

going for a b-12 shot in the morning and going to see if i can make an appt with him too.
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#16
(03-22-2012, 08:29 PM)SuperSleeper Wrote: Bill, I don't pretend to know all about the proprietary algorithms that autos use when adjusting pressure. But it is conceivable that they look at the pressure ranges in a percentage-sort-of way. Thus, the algorithm will only raise the pressure a certain percentage towards the high end, rather than looking at the raw cmH20 pressure numbers.

In other words, if you set the high-end pressure at 12, the algorithm may tell the machine to go to 80% of that pressure over a specific period of time, then 90% of that pressure during the next period of time, on up to 100% over a longer period of time. If that is the case, and you're experiencing obstructive events during the deep sleep periods that may occur later in the sleep cycle, the machine will not go higher fast enough to deal with a bad obstructive event... and will be restricted by the algorithm.

Raising the high-end pressure may expand those percentages enough to allow the pressure to raise to the higher levels faster, thus reducing the obstructive events.

Hope that made sense. Cool

made perfect sense. thanks.

the other thing is i have a history of laryngospasms on the machine or off. not often, but completely unexpected every time. the other night the pressure shot to the top as did the leak and i woke up in a big laryngospasm which makes it extremely hard to breathe. i couldn't get the mask off fast enough to start sipping water so i could breathe. it takes about a half hour to get back to normal breathing. i'm not sure if the pressure, the leak, or the dry throat triggered it. it was scary and makes me scared of the high pressures.

one of these days i need to write out all of these medical things so you guys know what i'm dealing with. i'm not the typical apnea patient with typical easy answers.

i've learned alot in the forum, so when i do talk to the sleep doc i will have specific things i can ask him and tell him and understand his answers.
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#17
Yep, I do think you need to consult with the doc on this, definitely... the info I've been offering would apply to "normal" sleep apnea patients, but you just ain't normal, Bill. Bigwink

Perhaps it could be that funny bug that keeps walking around your avatar... looks like it could jump off the page and into your nose... looks way too real to me. Too-funny

But seriously, so sorry you have these added complications. Let us know what you find out with the doc, okay?

SuperSleeper
Apnea Board Administrator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.



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#18
(03-22-2012, 08:24 PM)SuperSleeper Wrote:
(03-22-2012, 07:42 PM)Netskier Wrote: Is there evidence that higher max pressures reduce central events?

Howdy, Netskier...

There is debate on that. Some believe higher pressures increase centrals... others say it has no major effect. Truth is probably somewhere in between... and it depends upon the individual, I think.

Increased pressure can reduce obstructive events, thus lower overall AHI... and sometimes increasing the pressure slightly will increase centrals to a small degree, but decrease obstructive events to a greater degree, thus having an overall effect of lowering the AHI.

As far as I know (and we've had a ton of discussion on this in the old forum) there is no solid, reliable large-group study that has proven that higher pressures lead to increased centrals, although this contention seems to be prevalent out there among some professionals... but with very little publically-available scientific proof to back up that claim.

The whole point is that since everyone is different, experimenting with pressure settings scientifically is probably one of the best ways to determine optimum pressure settings. There isn't a one-size-fits-all pressure range, and there are real limitations even when doing an overnight sleep study in a lab, which is a completely different environment than a patient's bedroom.

In addition, eventhough a machine lists central events in the data... this doesn't necessarily mean that all of those are actual centrals. The machine just determined that there is an event and that it doesn't appear to be obstructive, therefore is generally assumed to be a central event, and listed in the data as a central or "clear airway" event.

Smile

From what you wrote, there is absolutely no evidence that high pressures reduce central airway events. The debate you discussed is whether or not higher pressures increase clear airway events. So if there is no evidence that higher pressures reduce clear airway events, then there is no reason to increase pressures to try to reduce clear airway events.

From what I can tell, increasing max or average pressures serves only to reduce OA or hypopneas, but not clear airway events nor unspecified apneas.
My age is none of my mind's business. --- Netskier
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#19
(03-23-2012, 01:06 AM)Netskier Wrote: From what you wrote, there is absolutely no evidence that high pressures reduce central airway events. The debate you discussed is whether or not higher pressures increase clear airway events. So if there is no evidence that higher pressures reduce clear airway events, then there is no reason to increase pressures to try to reduce clear airway events.

From what I can tell, increasing max or average pressures serves only to reduce OA or hypopneas, but not clear airway events nor unspecified apneas.

Correct. The idea is to have a net decrease in AHI, not a decrease in centrals. From a lot of what I've read, increasing pressure will not decrease centrals, but more likely the opposite, but as I said, there is debate on that - some say it has no major effect or that it actually has a slight positive effect in reducing centrals, depending upon the individual.

But in CPAP therapy, for better or worse, sleep apnea severity and effectiveness is generally measured in AHI, and increasing pressures to combat obstructive events, even though it may slightly raise clear airway events, still can cause a net decrease in the overall AHI. For each individual, (on constant-pressure CPAP) there is a "sweet spot", or best range of pressures (for autos) that will result in the lowest AHI levels, while still maintaining clear airway events within an "acceptable" range.

That is why making small, incremental adjustments to pressure over time, noting the effects on AHI (and looking at obstructive and 'central' events also) can result in lowering AHI levels. It's basic scientific analysis.








SuperSleeper
Apnea Board Administrator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.



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#20
(03-22-2012, 05:06 PM)greatunclebill Wrote: holy moly.

last night sleepyhead:
ahi 9.09
oa .15 (1 event)
ca 5.66 (38 events)
hypo 3.28 (22 events)
disrupted sleep, wake several times.

i could have central apnea? the numbers are different every night and usually between 5 and 10 ahi but the percentages are kinda the same.


Hey Bill, not sure if you still follow this thread, but:
I have almost the exact same numbers as you listed above.
Did you ever determine how to lower CA and Hypo?
Thanks!  J
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