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[Treatment] Help interpreting data -- all CAs??
#1
Hi all, I am new here but not to sleep apnea. Hoping someone can help me interpret the data from my new machine.

My story: I did a sleep test and was prescribed CPAP 6 years ago (my wife had been complaining about stopping breathing and gasping, and my BP had risen significantly). I used the Resmed S8 (pressure level 7) faithfully, BP dropped, and doctor said things were good after sleep test a year later, so I carried on for 5 years. No real problems (that I knew of) but realized recently that I was long overdue for a retest and a new machine. New doctor downloaded data from my S8 and found I had average AHI of 21, made appointment for a new sleep test (not until December!!) and arranged for an APAP loaner for a month (an S9 with pressure range 7-14). Based on the results from the loaner he prescribed an Airsense 10 Autoset (also set 7-14). I looked at the summary data from the S9 in ResScan (it didn't save detailed info) and the AHI results were all over the place (from 0.4 to 16) but he said it was because leaks were high due to my old mask (up to 72 L/min) and not to worry. So I got the Airsense 10 but decided I would monitor things myself -- did some research, installed Sleepyhead, etc.

I have been using the new machine and mask for 3 weeks. Leak is much lower but the results are still all over the place (AHI from 1.4 to 19.6, average 7.29) and almost all of my events are CAs. I tried to link a screenshot from Sleepyhead of a recent night with AHI=14.5 but haven't posted 8 times yet, can send it if anyone is interested.

My statistics for that night were

AHI 14.55
Obstructive Index 1.47
Hypopnea Index 0.49
Clear Airway Index 12.59

I note in the Sleephead "By Pressure" chart that events increase rapidly with increased pressure (AHI=8.8 at pressure 7, 13 at 8, 35 at 9, 51 at 10, 75 at 11). Does this mean that the pressure increases to stop OAs are causing CAs? I have seen discussions of EPR causing CAs and my level is currently set to 3, would reducing that help maybe? Should I be pushing the doctor to try an ASV machine?

One more issue: My best nights in the last 3 weeks were 7 in a row while on a cruise in the Caribbean (AHI from 2 to 6). I did a lot of things that are supposed to be bad for apnea (eating and drinking late in the evening, irregular sleep hours, etc.) but for some reason the sleep environment (I assume) more than made up for it. I have been working on replicating the conditions -- significant white noise (from ship's loud air conditioner), darker and cooler room than I am used to, softer pillow, etc. but no real success so far (AHI= 9.4 last night). The only other things I can think of are (1) Unlike at home, I spent no time at all using a computer or tablet so will try that on the weekend (no exposure to blue light before bed, etc.). (2) My wife is a light sleeper and changes position often during the night. The king bed on the ship was bigger and much more solid than the queen we use at home, so maybe her restlessness is affecting my sleep. Any thoughts?

Details I didn't mention: male age 60, 5'8" and 185 pounds, no other medical problems.

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#2
Are you using EPR on the new machine? EPR at 3 is same as Pressure Support at 3. It can cause CAs due to excess CO2 washout. You may want to eliminate EPR and test for 7-10 days and see if CAs go away. Then you may or may not want to re introduce them gradually (1 first for 10 days and then to 2 and then to 3).

Once you have done this experiment, report the results back in this same thread. We can then advise on other strategies.
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#3
Yup, EPR=3, wondered about that (mentioned in my message but it was rather long...). Will try turning it off for a while and report back. Thanks.
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#4
EPR is not a simple thing on Resmed. EPR is an average of 3-4 cycles, it only effects the initial start of exhale, and always tries to get back to full pressure. This is not a BiPAP like setting, it tries to soften the push into exhale from the end of inhale.
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#5
A lower EPR setting causes more CO2 washout due to higher flow on exhale.


Using FlashAir W-03 SD card in machine. Access through wifi with FlashPAP or Sleep Master utilities.

I wanted to learn Binary so I enrolled in Binary 101. I seemed to have missed the first four courses. Big Grinnie

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#6
Hi boss,
WELCOME! to the forum.!
Much success to you as you continue your CPAP therapy and good luck with your new machine.
trish6hundred
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#7
(09-05-2015, 12:25 PM)PoolQ Wrote: EPR is not a simple thing on Resmed. EPR is an average of 3-4 cycles, it only effects the initial start of exhale, and always tries to get back to full pressure. This is not a BiPAP like setting, it tries to soften the push into exhale from the end of inhale.
It doesn't average over i3-4 breaths as you mention. And it's just like BiPAP. The exact rise and fall pattern can vary but the basic idea is the same. There is a PDF on resmed site that shows it in waveforms for an S8.

(09-05-2015, 01:09 PM)AlanE Wrote: A lower EPR setting causes more CO2 washout due to higher flow on exhale.

The CO2 washout I mention here is not from the mask. It is from the lungs. And difference in IPAP and EPAP causes it.
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#8
(09-05-2015, 01:58 PM)AshSF Wrote: The CO2 washout I mention here is not from the mask. It is from the lungs. And difference in IPAP and EPAP causes it.

On a ResMed the lower the EPR number the more washout you will have.


Using FlashAir W-03 SD card in machine. Access through wifi with FlashPAP or Sleep Master utilities.

I wanted to learn Binary so I enrolled in Binary 101. I seemed to have missed the first four courses. Big Grinnie

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#9
EPR can cause CA for some folks, but not everyone or assume every CA events triggered by EPR. EPR automatically suspended during apnea event breathing drop 75% for 10 seconds or more and re-start when event is over and normal breathing resumes

I don't have an issues with CA or pressure induced CA, unlike S8 AutoSet ... S9 and A10 AutoSet can tell the difference and do not increase pressure if central event detected





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#10
(09-05-2015, 01:58 PM)AshSF Wrote: [quote='PoolQ' pid='129975' dateline='1441473925']
EPR is not a simple thing on Resmed. EPR is an average of 3-4 cycles, it only effects the initial start of exhale, and always tries to get back to full pressure. This is not a BiPAP like setting, it tries to soften the push into exhale from the end of inhale.
It doesn't average over i3-4 breaths as you mention. And it's just like BiPAP. The exact rise and fall pattern can vary but the basic idea is the same. There is a PDF on resmed site that shows it in waveforms for an S8.

Well since EPR tracks inhale pressure with a fixed offset, the exhale pressure will track whatever the inhale pressure is doing. According to:

http://www.resmed.com/us/en/consumer/sup...toset.html

"AutoSet devices assess breathing adjust pressure according to a five-breath average"

So in part you are correct it is not 3-4 breaths, it is over 5 breaths

I have now had both an APAP and a BiLevel Resmed machine and the inhale and exhale waveforms of the two machines look totally different.

The information I posted is based on what my sleep Dr. told me and was his reason for changing me to BiLevel (single breathe response verses moving average response). IMHO he is a very good Doctor and I trust his information. YMMV

Just in case anyone is interested here is the Resmed patent for EPR:
http://www.google.com/patents/US20120291785
What they chose to implement in their actual product line is another story.
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