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+--- Thread: ASV Questions (/Thread-ASV-Questions--48166)
ASV Questions - genasea - 01-12-2025
Hello, I have been using a Airsense 11 for one month (new to CPAP at that time) and have been experiencing CA's reported by the machine. It was recommended by the members on this board that my body might start acclimating to the machine and these may go away after time, or I could try an ASV machine.
I just purchased a used Resmed Aircurve 10 ASV and tried it for the first time last night, using pretty much the base settings (as recommended by members of this board). The settings are in the screenshots below.
From the data the ASV machine is producing, what the Airsense 11 considers a CA, the AirCurve 10 calls these a UA.
According to the Airsense 11, I pretty consistently have multiple CAs as I start to go to sleep. In the screenshot you can see that I have several smaller CAs when falling asleep with the Airsense 11. This occurs most every night.
Now that I am on the ASV, it appears I have traded multiple smaller CAs when going to sleep for one very long CA (last night I stopped breathing for 1 minute 3 seconds when falling asleep).
During this time, my O2 levels went down to 81 - which is below any reading I had while on the Airsense 11 over the previous month.
Additionally of concern, My O2 levels went from 96 prior to the single CA event, and remained in the 80s (shown in the screenshot) for 25 minutes where I once again went to 90 or above on my O2 levels. I have not seen this behavior with the Airsense 11. On the Airsense 11 the dips in O2 levels (below) 90, where much shorter in duration and recovered (above 90) much faster.
I am curious as to any thoughts or recommendations regarding these readings.
Thank you in advance for your ideas and comments, I appreciate them.
Prolonged low O2 levels after CA event on AirCurve 10 ASV machine shown here
RE: ASV Questions - SarcasticDave94 - 01-12-2025
UA is Unclassified events, the ASV doesn't have forced oscillation test the AutoSet and VAuto would use, testing for CA. Also the ASV expects there to be no CA when it gets done with your therapy.
I would first increase EPAP Min to 5, then later maybe to 6. It's not the goal in this suggestion to improve therapy, but I think you need more base air than 4 cmH20.
While you're in the clinical menu, change Essentials to Plus to see more on-screen.
Next OSCAR, edit the view slightly. You can have whatever you want pinned. But if you can present us with Events, Flow Rate, Mask Pressure (as you're on ASV), Leaks, skip Flow Limit.
This FL chart will probably be busy while on ASV. For sanity just ignore it. The ASV algorithm caused artifacts on most users of this machine. You can't fix FL on this, not a flaw.
RE: ASV Questions - genasea - 01-12-2025
Dave, thank you for your thoughts and ideas on this.
That makes sense about the forced-oscillation to identify the CA events on this machine. Thank you for this explanation.
I have increased the min EPAP to 5 as you suggested.
The 'Essential' setting in the clinical menu is already set to 'On' (I did not see a 'plus' but I think this is what you meant).
And I made the adjustment to the Oscar screen as you recommended.
Note: I have actually left off the leaks chart at it is always flatlined at 0 (I am fortunate that I get no leaking with the F20 Airfit mask)
RE: ASV Questions - SarcasticDave94 - 01-12-2025
Yep the Essentials was the referred item. I thought it had plus as an option.
OK try that increased EPAP min.
How did you feel for the usage of the ASV? This should guide as well.
RE: ASV Questions - genasea - 01-12-2025
I feel pretty rested so far today, thank you for asking. The previous night I was only able to get 4 hours of sleep so I had some catching up to do.
RE: ASV Questions - Sleeprider - 01-12-2025
Looking at the UA event, it is not surprising that it resulted in a low SpO2 as it was a 1-minute duration. This event was obstructive, and your machine hit you with the maximum pressure support 15-times through the event. You can see the tiny flow responses. A better graphical view is to look at Flow Rate and Mask Pressure rather than Pressure. Mask Pressure show each pressure trigger an cycle and the magnitude of the pressure, while the pressure graph simply shows the EPAP was at 4.0 and IPAP was at 19 through the entire even, and that EPAP was raised to 7 at the end of the event.
Since you obstructed at EPAP 4, I recommend you increase EPAP min to 6 or 7, and retain the other settings as-is.
RE: ASV Questions - genasea - 01-12-2025
Sleeprider - Thank you for your comments and suggestions. Both you and Dave recommend a higher EPAP minimum, so I will bump this up a bit more to 6 (since both you and Dave recommended this number).
Is there anything you would recommend for me to change regarding how the machine responds during the CA event? I see that it pulsed a lot of air at me during this time, without any apparent change in my breathing. Is there any other setting I should be looking at to possibly get a better result next time? And do you need any other data from the machine to make a determination?
Thank you again.
RE: ASV Questions - Sleeprider - 01-12-2025
That was an OA event, and you locked into it until your oxygen deficit was enough to arouse you to break the obstruction. We use the EPAP at a level that keeps the airway patent and prevents obstruction like this, then use the pressure support (IPAP) to resolve any central events and hypopnea. Your machine worked exactly as expected, and the increase in EPAP min is the correct solution. For your own understanding, you should zoom into that event and look at flow vs mask pressure and you will se exactly what happened. You were obstructing a lot prior to that event. Look at the mask pressure chart showing the pressure supplemented breaths leading up to the big OA. This shows much better breathing after EPAP was increased automatically. We want to preemptively increase the EPAP.
RE: ASV Questions - genasea - 01-12-2025
Sleeprider, thank you for the detailed explanation regarding what is occurring at that point. I appreciate the education.
I have increased the EPAP pressure to 6 and will see how that does tonight.
I will report back with the Oscar data in this thread tomorrow.