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High "Clear Airway" events
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zzzzk Offline

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Post: #21
RE: High "Clear Airway" events
(09-14-2012 05:30 PM)Sleepster Wrote:  
(09-14-2012 02:11 PM)givememoresleep Wrote:  I have also found my CA's are lower when on C-Flex as opposed to A-Flex.

C-Flex is the same thing as A-Flex. They lower the pressure a few centimeters upon exhling. It's called exhalation pressure relief (EPR).

BiPAP's induce CA apneas, so it's not surprising that EPR does too. It's probably an effect that subsides with time.

This is one reason why just a night or two of therapy shouldn't be used to establish an effect. It can take the human body weeks to adjust to changes in therapy pressures.

Hello, sorry, but I don't think your are correct. Here is what Supplier #9 web site says:

"A-Flex works in exactly the same way as C-Flex during exhalation. On inhalation, though, the pressure is increased more gradually to better match the normal breathing rythm of the CPAP user. With A-Flex the pressure doesn't spike up from exhalation to inhalation. It's a smoother and more comfortable increase. A-Flex also helps to prevent the CPAP machine from delivering a pressure that is too high. The difference between C-Flex and A-Flex is subtle. The bottom line is that if you want a CPAP machine that follows more closely your natural "breathing curve" then A-Flex is the technology for you."

I personally don't think it is useful having "A-flex" for a lot of people. It more slowly adds pressure on inhalation. I'm not a doctor, but if I have an obstruction, or I need air, I want it to unblock quickly. My CA's have gone down quite a bit by changing from "A-flex" to "C-flex" They are NOT the same to me.
(09-14-2012 02:11 PM)givememoresleep Wrote:  I have also found my CA's are lower when on C-Flex as opposed to A-Flex.

Yes, I continue to have this improvement with C-Flex. I'm starting to think A-Flex does more harm than good for many people.
(This post was last modified: 09-15-2012 11:57 AM by zzzzk.)
09-15-2012 11:41 AM
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Sleepster Offline
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Post: #22
RE: High "Clear Airway" events
Hmmmm.... Interesting. I didn't know that. I wonder then if Bi-Flex is any different?

The manual states that Bi-Flex does modify the pressure curve so it may be doing something similar to what A-Flex is doing.

Sleepster
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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.
(This post was last modified: 09-15-2012 01:44 PM by Sleepster.)
09-15-2012 01:38 PM
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zonk Offline

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Post: #23
RE: High "Clear Airway" events
CPAP does not correct centrals
Some folk (Not everyone) when they start PAP therapy might have centrals appear in response to pressure
More likely things would improve as they use the machine more and get accustomed to the therapy
09-15-2012 04:43 PM
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zzzzk Offline

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Machine: System One RemStar Auto with A-Flex (550P)
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Post: #24
RE: High "Clear Airway" events
We'll after MONTHS of high "clear airway's" I changed from "A-flex" to C-flex" and my "clear airways" have gone down a lot! Smile

Now a number of people have said the same thing. This is significant for people to at least try, to me. My theory is that "A-flex" actually causes many more centrals for some people, not so much that they prevent them, but I could be wrong. This, just as many people say that higher pressure causes centrals. Perhaps it deceives the body in some way because the pressure drops on inhalation in the beginning? Interesting...
09-16-2012 11:51 PM
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archangle Offline
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Post: #25
RE: High "Clear Airway" events
I think the various forms of "FLEX", EPR, exhale relief, and bilevel are something that has to be experimented with for each person. Each option here seems to work great for some people, and are bad for others. Both in terms of measured results, and patient comfort.

It seems to require tinkering.

Yet another reason it's important to have a fully data capable machine and monitor the results.

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09-17-2012 12:41 PM
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archangle Offline
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Post: #26
RE: High "Clear Airway" events
(09-14-2012 05:30 PM)Sleepster Wrote:  BiPAP's induce CA apneas, so it's not surprising that EPR does too. It's probably an effect that subsides with time.

That seems to be highly variable. Bilevel seems to help some people with CA, but it may harm or be ineffective for others. Bilevel is one of the first things they tend to try for people with CA.

(09-14-2012 05:30 PM)Sleepster Wrote:  C-Flex is the same thing as A-Flex. They lower the pressure a few centimeters upon exhling. It's called exhalation pressure relief (EPR).

Respironics has "CFlex, AFlex, CFlex+, and BiFlex". There are differences in the shape of the pressure waveforms between Flex versions. Some people find big differences between Flex flavors. Yet another thing that needs tinkering. ResMed does "EPR", which is more like a simple square wave with two pressures.

All the "Flex" names are trademarks of Respironics. "EPR" is a trademark for ResMed. "Exhale relief" is the generic term.

BiPAP is Respironics trademark, VPAP is ResMed's trademark, and "bilevel" is the generic term.

Get the free SleepyHead software here.
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Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
09-17-2012 12:53 PM
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Moriarty Offline

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Post: #27
RE: High "Clear Airway" events
(09-16-2012 11:51 PM)zzzzk Wrote:  ..... My theory is that "A-flex" actually causes many more centrals for some people, not so much that they prevent them, but I could be wrong. This, just as many people say that higher pressure causes centrals. .....

I think it is important to not confuse the 'Clear Airway' events with the 'Central Apnea' events that are identified in a proper sleep study.

The terms are not synonymous. A 'Clear Airway' event may be a result of true Central Apnea or may be a result of the machine not correctly identifying the event - particularly when exhalation relief is in operation. This could be because the machine is probing an 'empty' hose that effectively increases the dead volume that it is looking into. If you are a bit slow to inhale how does the machine decide that you are in apnea? - it is relatively easier if the pressure is constant.

I think it is possible that we over-think some of the things we see in our data. The machines are the result of very clever designers but that do not have any neurological connections to you so they can only do so much.

The very important bottom line is that if anyone is concerned that their Clear Airways events have increased and is worried that they may be Central Apneas then they should consult their physician to make sure that they have not developed true Central or Complex Sleep Apnea.

Cheers

David
09-17-2012 06:56 PM
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zzzzk Offline

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Machine: System One RemStar Auto with A-Flex (550P)
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Post: #28
RE: High "Clear Airway" events
(09-17-2012 06:56 PM)Moriarty Wrote:  
(09-16-2012 11:51 PM)zzzzk Wrote:  ..... My theory is that "A-flex" actually causes many more centrals for some people, not so much that they prevent them, but I could be wrong. This, just as many people say that higher pressure causes centrals. .....

I think it is important to not confuse the 'Clear Airway' events with the 'Central Apnea' events that are identified in a proper sleep study.

The terms are not synonymous. A 'Clear Airway' event may be a result of true Central Apnea or may be a result of the machine not correctly identifying the event - particularly when exhalation relief is in operation. This could be because the machine is probing an 'empty' hose that effectively increases the dead volume that it is looking into. If you are a bit slow to inhale how does the machine decide that you are in apnea? - it is relatively easier if the pressure is constant.

I think it is possible that we over-think some of the things we see in our data. The machines are the result of very clever designers but that do not have any neurological connections to you so they can only do so much.

The very important bottom line is that if anyone is concerned that their Clear Airways events have increased and is worried that they may be Central Apneas then they should consult their physician to make sure that they have not developed true Central or Complex Sleep Apnea.

Cheers

David

Hi David,

I agree with part of what you say, but some of us are suffering and can't go to the sleep center constantly. Also, most modern doctors will spend about 5 minutes with their patients analyzing the data. Even when I had insurance, the doctors I had spent next to no time troubleshooting my issues because I had a cheap HMO. All they did was slap a cheap CPAP and mask on my face and said, bye. Sad, but true. Of course, a doctor, with the expertise, time, and caring, is the best. However, I think many people make a great mistake just "trusting" everything their doctor says. I appreciate the input of changing the setting from a-flex to c-flex, I feel better and my ahi is down. I think it is wise to let people know options so they can test their options. Especially when I doubt changing this setting will harm people. I doubt real centrals are just going to go away and not show up in the data with this change in setting.
09-17-2012 08:22 PM
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Moriarty Offline

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Post: #29
RE: High "Clear Airway" events
(09-17-2012 08:22 PM)zzzzk Wrote:  .... but some of us are suffering and can't go to the sleep center constantly.....

OK zzzzk - I hear what you are saying and I understand the difficulties of organising and undergoing sleep studies without insurance.

I guess I am fortunate that I have insurance that covers most of the sleep study and about half of the Physician - but they only pay a quarter of the machine and nothing for the masks... lousy mob.

Having a slight understanding of the way the machines work I would not get too worked up over increased CA events following a pressure or mask change if the increase in CA is balanced more or less by a reduction in OAs and/or hypopneas... The supplier I use is only concerned about the summary AHI number and the hours used and don't look at the graphs unless they are unhappy with the AHI.


HTH

Cheers

David
09-17-2012 11:56 PM
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Sleepster Offline
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Post: #30
RE: High "Clear Airway" events
(09-17-2012 12:53 PM)archangle Wrote:  
(09-14-2012 05:30 PM)Sleepster Wrote:  BiPAP's induce CA apneas, so it's not surprising that EPR does too. It's probably an effect that subsides with time.

That seems to be highly variable. Bilevel seems to help some people with CA, but it may harm or be ineffective for others. Bilevel is one of the first things they tend to try for people with CA.

The study results were posted here recently and are consistent with my experience. Patients with simple OSA wer put on BiPAP's and they induced CA's. In my case it drove my AHI up above 15 for about 10 consectutive days. My doctor's remedy was to lower the pressure. My AHI now averages between 1.1 and 1.4.

Quote:Respironics has "CFlex, AFlex, CFlex+, and BiFlex". There are differences in the shape of the pressure waveforms between Flex versions.

Yup, I realize that now. My BiPAP has has Bi-Flex and according to the manual it does alter the shape of the presssure curve. It's the only Flex option available in BiPAP mode. I don't know if putting the machine in CPAP mode would make a C-Flex option available. I'll have to do some tinkering. Since it's a BiPAP I could lower the Flex and raise the EPAP. See if that makes a difference.

Sleepster
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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.
09-18-2012 07:33 AM
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