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+--- Thread: ASV for flow limitations in mild OSA (/Thread-ASV-for-flow-limitations-in-mild-OSA)
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ASV for flow limitations in mild OSA - logit - 03-31-2021
Has anyone tried or had any luck using an ASV to help with flow limitations? At PS > 4, I have a lot centrals and I'm wondering if the variable pressure support of an ASV might help. I know it's an unusual use case for that machine but curious if anyone has any experience with this.
RE: ASV for flow limitations in mild OSA - Sleeprider - 04-01-2021
If you need pressure support of 4-5 cm, but have enough central events to justify adaptive pressure support, then the ASV will treat that problem and give you good results. If your central apnea index is less than 2/hour the problem is likely pretty minor and while it will treat CA, you have to wonder if the often disruptive changing PS is worth it. You have very little data posted and I guess it's your decision if you want to pursue this because we have almost nothing to go on that would suggest your need for PS 4.0 + or the severity of CA issues. What is "a lot of centrals"? How disruptive are your flow limitations at PS less than 4.0? Have you tried using a high trigger sensitivity?
RE: ASV for flow limitations in mild OSA - logit - 04-01-2021
Thanks for jumping in sleeprider, you are a hero on these forums. I haven't tried using higher trigger sensitivity, what settings do you recommend? My machine is currently on medium. Attached a flow rate chart that is pretty typical. It doesn't last all night but as you can see a lot of these flow limitations aren't marked in the flow limitations chart so it's a little hard to use the flow limit metric flagged by the machine. My numbers look good overall but I've never actually felt better so I'm wondering if these flow limitations could be the reason. It's been a while since I tried higher PS but it was in the range of ~2/hr. Do most people find the adaptive pressure support pretty disruptive?
[attachment=31168]
RE: ASV for flow limitations in mild OSA - Sleeprider - 04-01-2021
The type of inspiratory flow limitation (IFL) we see on your flow rate is Class 2 which may be the airway collapsing during inspiration and quickly reopening. If this chart is typical, you do not have a central apnea problem or therapy onset centrals. We can reduce the number of CA events by moving the trigger sensitivity from medium to high. I personally use this setting, and while zero AHI is not a reasonable goal to pursue, this can reduce some of the random CA events by causing the machine to kick into IPAP with less inspiratory flow as exhale ends.
The class 2 IFL might respond to higher EPAP or slightly higher pressure support. In this sequence your EPAP is at 7.5 and PS 4 is delivering IPAP 11.5. We can see a slight dip in flow as expiration ends, and this will likely diminish with high trigger sensitivity. Some of the irregularity is cardioballistic effect during expiration and we can ignore that. I would rather that you implement only one change at a time, so let's put any pressure changes on the back-burner while you try high trigger sensitivity first. Please be sure to include full-night charts with any zoom so we can have some context on whether this is typical.
RE: ASV for flow limitations in mild OSA - SarcasticDave94 - 04-01-2021
Hi logit,
With your current VAuto, there's been some success with CA combat by way of changing trigger to high or very high. I'd suggest one step up to high and see what that does. Compare events and how it feels to give it a grade, so to speak.
I've got the ResMed AirCurve 10 ASV and it did a great job at CA combat, but it lacks manual control like this trigger setting. And insurance is pretty strict on issuance and approval of an ASV. In other words you need to jump over a lot of hurdles and check a lot of boxes, such as a diagnostic sleep study with 50% or more CA. They're not likely to issue ASV to treat treatment emergent CA or CA that can be avoidable with current machine settings.
Then to top it off, the ASV isn't particularly good at flow limit issues. When my ASV was working with me, my FL was actually flat, and not the same as most other ASV users.
How about discussing your historical account of CA. What did your diagnosic and titration show? What about current treatment and the VAuto on the CA? Just so you know where you're at now and to help us direct your target to fight. It may be that ASV isn't a fight you need to take on. But if it is, we can help with that too.
RE: ASV for flow limitations in mild OSA - logit - 04-01-2021
Sleeprider, thank you, wil try higher trigger sensitivity and follow up with more charts + full night. CA is not an issue on PS 4, but once I move higher it does become an issue.
> Class 2 which may be the airway collapsing during inspiration and quickly reopening
Sometimes when I'm awake I experience something which I can only describe as a "throat snort", it's an audible sound that occurs during inspiration. I can feel it slightly under my adam's apple and is always extremely brief. Has anyone ever described this before / any idea if it's related?
Dave,
CA is only an issue at higher PS, which I've tried to help with flow limitations. Diagnostic studies ranged from 12-20 RDI, CA was never an issue in any of them. Titration study for Bilevel tried two pressures 10/14 and 11/15, they prescribed 10/14 but i cannot tolerate that level of pressure. I get leaks, aerophagia, it's overall extremely uncomfortable and does more harm to my sleep than help. RDI < 1 with those settings so supposedly working but I think the pressure itself is more disruptive than the arousals.
I have previously had a matryx titration for dental device. This was the best, most refreshing night of sleep I've had in years but the dental device itself didn't do anything except completely screw up my bite.
My sleep doc would not prescribe an ASV. I honestly would do whatever it takes to fix my sleep and would happily pay for an ASV out of pocket (if this is even possible).
Going to follow sleepriders suggestions and post back with result. Thank you both.
RE: ASV for flow limitations in mild OSA - SarcasticDave94 - 04-01-2021
OK I copy. If you're having any troubles with pressures now, the ASV might be even worse. Its algorithm is designed to blow harder during CA events. And then too if your CA is rather on the lower side, again it's very likely not the best choice. It does most things well but it may be a bit overkill for you according to what I've seen thus far.
On the leak issues generically I suggest review of the overall mask fit. I do not think the machine mask fit works well other than to cause madness. Check that there's no physical damage to the mask and for proper adjusting the straps. Some mask models will be a better choice. Unfortunate it typically requires trying them out under therapy pressures to see how they'll do.
RE: ASV for flow limitations in mild OSA - logit - 04-03-2021
Changed my trigger sensitivity to high. I spliced together flow limit shows for the first ~10 minutes of my night last night. This is very typical of the sleep onset for me and i frequently wake up 10-15 minutes after falling asleep. I get woken up shortly after the third screenshot. This pattern doesn't last all night but it comes and goes. Sometimes my flow limitations look fine, other times it looks like these screenshots for a while and is not marked on the flow limitations chart.
As far as leaks go, I've tried a dozen or so masks, full fasks masks just do not work for me, they can't fit my face. I've even tried the face shield and it didn't work. I use p10 with a chin strap - I know sleeprider is not a fan of chin straps but I don't have a choice. If I don't wear it i get a ton of leaks through my mouth and full-face masks have never fit me. I position it so that it fits underneath my chin so it pushes upwards and doesn't compress my jaw backwards which should prevent some of the issues associated with chin straps.
RE: ASV for flow limitations in mild OSA - logit - 04-03-2021
Here's the overview for the night and the zoomed in section
RE: ASV for flow limitations in mild OSA - sheepless - 04-03-2021
post a 10 minute view scale screenshot of your april 2 flow rate from about 20:26 to 20:36. do you have a history or awareness of restless legs or periodic limb movement? view scale can be adjusted by moving the view size slider at the bottom of the 'daily'/'events' tab.