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I don't know the reason or theory of why with some folks have CA events increase when started on cpap. That happened to me on an AUTO machine. The ipap would go up in response to apneas and the pressure would go up causing more apneas in a cycle. There are some good videos on YouTube about sleep apnea, some of the videos are on ASV which may be helpful. Doctors used to be loathe to prescribe ASV machines because of the expense, but as more people are having the same experience as you the percentage of ASV's increase. ASV is the machine of choice for central or complex apnea.
Good luck. I don't think an AUTO would be an improvement. I am no authority, though.
(10-16-2013, 03:21 PM)rgrxdp Wrote: Thanks for the help everyone. Does anyone have a theory why CA increases with pressure while OA decreases?

The experts think there are several reasons why pressure gives some people CA. In part, your urge to breathe is partly triggered by high CO2 levels in the blood. With CPAP pressure, you may inhale more deeply, flushing out the CO2 from your blood. You may stop breathing for a while until the CO2 builds back up. Unfortunately, your O2 levels may drop while this is happening. It's a bit like how you get dizzy when you hyperventilate.

Overinflating the lungs also stretches out some cells in the lungs and effects the feedback system reducing the urge to breathe.

The body is a complex system with lots of feedback mechanisms. Sometimes tinkering with the system screws things up.

Some info here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2576324/
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(10-13-2013, 05:43 PM)rgrxdp Wrote: I had 73 AHI during my sleep study, but CA ( I guess that means central apnea ) was 0. Now that my machine is set at pressure 10, I have about 10 or 11 AHI with about 9 of that CA. I this for real? Why would pressure make my CA worse...?

(10-13-2013, 10:19 PM)PaulaO2 Wrote: To the original poster:

Yes, it happens and is quite common. I would not worry about it for right now. How long have you been using the machine?

If it has been more than a few weeks, let the doctor know. What he will probably do is drop the pressure down a few points and let you get used to that then raise it back to the treatment pressure.

Hi rgrxdp,

It is fairly common that, at first, standard PAP treatment (the purpose of which is to prevent/reduce obstructive apneas) may cause an increase in Central Apneas. But as the body gets accustomed to PAP treatment, the Central Apnea Index (average number of central apneas per hour) usually gradually diminishes until it no longer dominates the AHI.

Often (but still only for a minority of users) EPR, Flex or other forms of exhalation pressure relief can increase the number of central apnea events. But exhalation pressure relief can also decrease the number of obstructive events, especially when using an auto-adjusting APAP machine.

When the CAI does not reduce to acceptable levels within a few weeks or months, then, depending on how large the CAI is, you may qualify for an Adaptive Servo Ventilator (ASV) machine. ASV machines may take longer to get used to and comfortable with, but are able to prevent/treat both obstructive and central events.

I think the relevant US Medicare rules are something like this:
(1) the CAI must make up a majority of the CAI
(2) the CAI all by itself must be over 5.0
(3) an ASV titration must demonstrate that ASV treatment significantly improves the AHI (like, by a factor of two of more, I think)

I think some private US medical insurance companies have stricter rules, such as that the CAI must be 15.0 or higher with the patient's present PAP machine.

Take care,
--- Vaughn
Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.

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