Respiratory depression from ASVauto?

[Dutchie]

Hi guys,

Not too long ago I had an in lab titration night where my AHI maxed at 8 and I was given a BiPap on trial. The recommended settings were 10/14, as this gave the most stable REM sleep. I've slept with this machine and setting for a while to treat the apnea/hypopnea and flow limitations and I actually felt worse than sleeping with my own Resmed Aircurve 10 ASV machine:

https://imgur.com/a/B0VvOYr



Even though my AHI is excellent, I still suffer from poor sleep quality due to RERA's and inspiratory flow limitation. To also eliminate the RERA' with, I figured to give the Resmed ASVauto mode algorithm free reign with the following settings:

epap min 9
epap max 10
PS min 3
PS max 8

I woke up halfway through the night and felt horrible with a lot of tension/anxiety and changed the settings to ASV, that's why in the attached screenshot it doesn't show the ASVauto settings, but the settings I used in the latter part of the night. For some reason the pressure increases a LOT and I think having too wide of a PS margin, combined with the way the machine responds to my breathing is triggering respiratory depression / alkalosis. I feel very tense during the day, with a knot in my stomach and can't seem to catch a deep breath. The data:

https://imgur.com/a/CTbm1gL


So my question are:

Is this actually respiratory depression / hypoventilation?
Would I do better configuring my ASV to a Bipap? (I prefer the more 'natural feel' of breathing of an ASV over going to BiPap)

Thanks

[Sleeprider]

I'm going to give you official authorization to borrow my settings, EPAP min 9, Max pressure 18, PS 4. Your machine does not have variable PS. Here is the deal....your machine is set to fixed VPAP-S pressure with 10.0 EPAP and 14.0 IPAP. Change this to Mode Vauto, EPAP min 9.0, Max pressure 18.0 and PS 4.0. I think you may need higher PS, but let's start with Vauto mode and variable pressure to deal with the obstruction, and go from there. Whoever wrote your prescription doesn't have a clue, but I just corrected it for you.

[Dutchie]

Thanks for the authorization   I actually don't have the Bipap VAuto device anymore. I could only use it for a month on trial basis and had to hand it back in. I'm not being seen or guided by a lung doctor or sleep lab anymore, they tend to focus on AHI. I don't want go through the hassle of finding another doctor, explaining what UARS is, and trying to convince them to grant me another trial for a VAuto.

Since it's mostly RERA's and flow limitation I'm trying to treat, wouldn't I do better on a fixed epap and a variable PS? My AHI is 0 after all. ASV machines can ramp up the PS when needed and from what I understand the Philips Respironics algorithm targets peak flow limitations and could provide a better response to my flow limitations.

A befriended co-UARS patient alerted me on the differences:

https://web.archive.org/web/202110060150...-with-ifl/

Last last night I fixed the epap at 9 with a PS of 5. It's not perfect in Oscar, and I still see RERA's, but it sure beats waking up with a racing heart on ASVauto mode. Do you reckon I should increase the PS in increments of 0.2?

https://imgur.com/a/dlLWyOF

[Sleeprider]

I missed the change to ASV. I think the 5 cm PS spread you are using is typical for individuals using ASV for UARS, and the EPAP simply needs to control obstruction. After seeing many individuals try ASV in this capacity, I have concluded that the results are mixed to negative compared to conventional fixed bilevel pressure support. The reason ASV normally results in poor sleep is that the constantly changing pressure support is disruptive to sleep, and the ASV is better suited to maintaining a constant minute vent rate rather than correcting a flow limitation. A restricted upper airway which leads to the symptoms of UARS tends to be a much more fixed target and is best treated with the pressure support that relieves the airway resistance. The only time I would suggest someone consider ASV is when the therapy pressure support results in central apnea, so that a backup trigger and adaptive PS can address that issue. Upper airway resistance tends not to change much from breath to breath, however other factors like sleep position may affect the amount of pressure needed to stent the airway or may change the need for PS. With all that said, it would be a lot easier to help you if you posted charts with flow rate, mask pressure, inspiration time, flow limits and leaks. My guess is that your PS min of 3 is insufficient for your UARS, and you mostly don't need the PS mas, but with ASV you don't get that choice.

[Dutchie]

Having slept with a 'fixed' PS of 5 (actually 4,8 - 5), I do feel somewhat better. Not exactly good, but it's not as bad as having ASVauto mode on and alternating between 8 and 20 breaths per minute every couple of minutes.

One thing I keep noticing is that every couple of minutes I seem to gasp/inhale deeply, followed by what seems shallow/choppy breathing. My working theory: the pressure support is not enough to comfortably breath  causing frequent an inspiratory flow rate not rounded at all, and I have to gasp to catch up with breathing. Not to sure why my breathing is 'smaller' in between such a these gasps. Can these be considered arousals and does the airway need time to stabilize again?

https://imgur.com/a/xZGVplW


Also, I am contemplating buying a used DSX960D off of Dotmed, to see if the Philips Respironics ASV peak flow focussed algorithm works better than the minute ventilation focussed Resmed ASV algorithm. 

• Is there much difference between fixing the PS for an ASV to act as a Bipap and actually buying an Bipap? I find breathing with an ASV much more comfortable.
  
• Then again, is the airway stenting more consistent or stable with the Bipap? I just found the 'forced breathing' of the Vauto uncomfortable. Perhaps this was a matter of tweaking the trigger times?
  
• Based on a fixed PS of 5 over 9.2, would you recommend me gradually increasing the PS, while also decreasing the Epap? After all, my AHI is 0.
  

Anyhow, thanks for taking the time to look into my case and responding Sleeprider. I very much appreciate it

[Dutchie]

By the way, could the gasping be explained by trying to get enough air through the nose, failing, and switching to mouth breathing, resulting in more collapse due to mouth breathing? My nasal breathing has deteriorated over the last couple of months due to what I believe is stress and poor sleep and I could be in a cycle of poor sleep, nasal congestion and possible collapse of airway by switching from nasal to mouth breathing. Does that make sense based on these screenshots: https://imgur.com/a/xZGVplW