OKCSleepDoc wrote:So I spoke with Resmed Clinical Specialist As Promised.
Before I begin, I would comment that your flow limitation overall is actually pretty well controlled, even though you have a few spikes, they are addressed. I think the more important thing is that your AHI is well controlled on the ASV whereas it was not before.
That being said, I spoke to the Resmed clinical Specialist and he commented essentialy exactly what RobySue said. Your Flowlimitation was likely taken care of with your AutoMachine due to the machine being able to adjust the pressure when flow limitation was encountered. Your curent device is on Fixed Adapt SV mode so therefore as the EPAP is fixed, the flow limitatoin may be occuring given your pressure support settings. The way you could test this would be to either increase your EPAP by 1 cm H20 to see if it addressed it, or to raise your pressure support minimum from 2 to 3. Essentially you probably need a bit more pressure and if the PS falls to 2 on top of 7, perhaps 9 or 10 cm H20 is enough to cause some flow limitation which is why the machine ramps up the pressure every time that is encountered and it resolves the FL.
I hope that makes sense. Sorry it took me a while to call Resmed for you (RobySue was right on the money anyways!).
Thanks so much RobySue, you're a gem, and especially OKCSleepDoc for the follow-up support I needed. You're a credit to the profession. My bad for not replying sooner. I've been away from the board for awhile and missed your post.
I agree, as have others such as John and Avi, that AHI is of primary importance relative to FL detailed graphs which, after all, are mathematic derivatives of the shape of air flow wave forms. So I've been happy to see AHI so well controlled by my new ASV machine from June until now. At the same time, most educated individuals in technical fields do not just hang their hat on their favorite "hook" and disregard other signs that look questionable and raise their eyebrows. Thus my focus on the graphed flow limitations was initially something I wanted to get evaluated because I recognized that they were maxed out on the charts, and that needed to be explained or rationalized. It's also a challenge to learn as much as you can about how the various sleep parameters fit together.
Re. your post, does "that make sense" to me? Yep, in that I'm beginning to get the gist of what both of you are saying, but I need to do some homework to better understand the concept of "pressure support" (aka PS) and how it plays here. And so I have been varying EPAP incrementally, and holding at each level for a few days or up to two weeks at some levels. I went first from 7 to 7.6 to 8 cmH2O, then down to 7.4, 6.8, 6.4, 6 and then back up to 7. Am now reviewing the resulting AHI and IPAP Lo and Hi at each level that SleepyHead has recorded. I'm not confident that I can trust SH's PS numbers though. And I'm not sure how to manually figure my own PS figures. SH seems to be saying PS min and max stayed fixed at 3 and 15cm even while IPAP Lo and Hi varied each time I made a change in EPAP settings.
Again, thanks so much for the great backup on this topic.