APAP lower pressure questions

[Pupcake]

I'm a newbie who switched from 6.0 CPAP to APAP 6.0-20 last week. I was still having Many events so they switched to 8.0-20. Then it seems like my pressures just spiked every 7 min. I personally (bad girl)raised the lower pressure to 9.0 which lowered my AHI to <1.0 but still spikes. Is that what I want. Do I want to raise it until it doesn't spike anymore, or will that blow my lungs up?

I (hope) I have attached screen shots below

https://www.dropbox.com/s/jqxfjf04yr8xb ... 6.png?dl=0

https://www.dropbox.com/s/hvawh0lzylmf0 ... 4.png?dl=0

https://www.dropbox.com/s/tk6l5613q99jl ... 3.png?dl=0

[Pupcake]

OK that didn't work

[Julie]

DL to Imgur.com, size appropriately and leave a link in this thread to the graphs.

[Pupcake]

step 2

http://imgur.com/a/Ffz3D

[robysue]

Pupcake,

I'm a newbie who switched from 6.0 CPAP to APAP 6.0-20 last week. I was still having Many events so they switched to 8.0-20. Then it seems like my pressures just spiked every 7 min. I personally (bad girl)raised the lower pressure to 9.0 which lowered my AHI to <1.0 but still spikes. Is that what I want. Do I want to raise it until it doesn't spike anymore, or will that blow my lungs up?

Are you talking about the triangular sawtooths in the pressure curve?

If so, those are a part of the PR System One's Auto algorithm: They're part of the PR Search algorithm, which is how PR machines proactively search for the "optimal" pressure even before breathing has deteriorated to the point where a flow limitation can be scored. And the only way to "get rid of them" is to change to CPAP mode or to set min pressure = max pressure in Auto mode, which effectively mimics CPAP mode, but allows the machine to record (but not respond to) flow limitations and VS snores.

Here's what you need to understand about the PR Search algorithm: When the breathing is relatively stable, the PR search algorithm does a 2 cm test increase in pressure approximately every 7-10 minutes. The machine is carefully evaluating the shape of the inhalations to see if there is any improvement in the "roundness" of the inhalations. If no improvement is seen, the pressure is then lowered back down to the base line pressure. If improvement is seen, the machine continues to increase the pressure at the same rate until one of two things happen: No further improvement is seen in the wave form OR the max pressure setting is reached. Once no improvement is seen, the machine backs the pressure off to the last pressure setting where improvement WAS seen and that effectively becomes the new baseline for a while.

When the pressure has been raised above the min setting for a certain amount of time, the machine does a test decrease as part of the Search algorithm. The machine will keep lowering the pressure until one of two things occurs: The min pressure setting is reached OR a subtle deterioration in the flow rate is detected; in this case the machine then increases the pressure back up to the previous level.

Your data clearly shows both parts of the PR Search Algorithm in action.

And the upshot of all this is: You can't increase the pressure to eliminate the pressure spikes that are caused by the PR Search Algorithm. This is the way the machine is designed to work.

[Pupcake]

Thank you.

You answered my question quite well!

Pup

[palerider]

follow these instructions next time for easier posting:
https://sleep.tnet.com/resources/sleepyhead/shorganize

[cpapernewbie]

I am glad I read this thread. That was a very insightful answer to a great question.

Thank you to robysue and also to pupcake for asking the question.