ASV users: the everything ASV thread.

[JohnBFisher]

... Rise time and Flex. ...

That's a good question. The answers I am providing are "As I Understand Them". I might be wrong. But I think this is all correct.

First, I do know that "Flex" is a technology first developed by Respironics to address the discomfort of sleeping against a continuous pressure provided by CPAP units. This technology/technique drops the pressuring during the expiration phase of breathing. It is NOT Bi-Level PAP therapy (BiPAP), which has a prescribed pressure for both inhalation and exhalation. Rather, it drops the pressure during exhalation to make it easier to breathe. As I've noted before, this drop does not "support" breathing. The pressure will not be enough to maintain an open airway.

Respironics then went on to create different Flex technologies for different types of units. For example, there is a Flex technology for BiPAP units. But they basically work on the same principle - decreasing the pressure a little during exhalation to make it easier to breathe.

Second, the "Rise Time" value on the ASV unit shows the ventilator background of the ASV units. Rise time determines the speed with which the flow or pressure of the ventilator rises from exhalation to inhalation. The time it takes for this switch from one to the other is the "Rise Time".

... Can someone explain what they are and what they are supposed to do, ...

See above.

... what is the difference between rise time and flex, ...

See above.

... and what is the difference between a rise time of 1 and a rise time of 6, ...

A rise time of one (1) is a VERY short rise from exhalation to inhalation. Most people would find that to be COMPLETELY unacceptable. To me (when I've tinkered with it) it feels as if I was suddenly having some shop pressure tool pumping me full of air. No thanks!

A rise time of six (6) is much longer time to rise from exhalation to inhalation. Most people may find that to be too long. In fact, it might actually limit the amount of air that you inhale. If it is too long and you the unit decides you have not cycled your breathing it might actually truncate the intake and switch you to exhalation pressure. Also not good. To compensate, a long rise time may require a higher pressure from the ASV to meet your needs.

So, you might try to see if a Rise Time of 5 or 4 would help reduce the high pressures, by moving you more quickly to the inhalation pressure. But don't overdo it by moving to a Rise Time of 2 or 3. You would feel very rushed in that case.

... and the difference between a 1 and 3 in flex? ...

The 1 to 3 denotes the drop off in pressure during the expiration phase of breathing. The least decrease in pressure is at a setting of 1. The greatest decrease in pressure is at a setting of 3.

... Can these settings impact therapy and AHI? ...

Absolutely, see the last graph in the following summary of a couple studies. At 3 the pressure decreases to the point that the number of obstructive sleep apnea events increase. The more you back off the pressure, the more it is likely the pressure will not be enough to avoid an obstructive apnea.

http://cflex.respironics.com/PDF/101663 ... tudies.pdf

Interestingly, due to the decreased pressure the studies confirm my own experience. I got better sleep with a C-Flex setting of 1.

As to the Rise Time setting, as you can see a slightly lower Rise Time might decrease the top pressure to help you attain normal respiration during a central apnea.

Hope that helps.

[ameriken]

Thank you John, that is excellent. I know some time ago I was trying to find some settings between the flex and rise time, and obviously was quite sure about what I was doing. Ok, I had no clue. I didn't think those settings could affect therapy, however over the past few weeks, Imy AHI's have risen for no other reason, and I've had 12's, a15, 16 and a 20, even though nothing else has changed and there were no leaks.

I'll see what I can come up with and hopefully figure out a way to get my AHI's back into the 4-10 range again.

[sickwithapnea17]

thanks so much! I wish someone would start a thread with descriptions of all the different ASV settings. I'm going to start one.

[ameriken]

thanks so much! I wish someone would start a thread with descriptions of all the different ASV settings. I'm going to start one.

That's kinda sorta some of what I was hoping to get into this thread since there's not a forum for ASV's.There's a lot to learn about these machines.

[ameriken]

That's a good question. The answers I am providing are "As I Understand Them". I might be wrong. But I think this is all correct.

Hope that helps.

Thanks John, that was very helpful. As I played around with the settings it helped me understand what was going on with each one. I don't like the flex at all and so I went with turning the flex off and then on with a rise time of 4. That was quite comfortable and felt more natural. I slept well with it and I actually felt better today. I'm wondering if the flex setting is what screwed with my AHI's. I'd check my software but that's a whole 'nudda issue, the password expired with no warning and I can't get it to work nor will it reload.

Anyhow, thanks again, it was very helpful.

[Kody]

Have a question about the use of ASV's. Last time I saw my RRT she remarked that another patient after being on the same machine as mine for 18 months was able to go to just a regular CPAP Machine. Like it was a "good" thing to get off the ASV. I commented at the time that I liked my unit because I was able to breath easier with it than a CPAP. Still trying to put this puzzle together, but is it one of the goals to be able to switch down to a regular CPAP Machine rather than stay on an ASV? I know these are much more complicated and expensive, but I thought what ever works for you is what you need. After being on an ASV for a prolonged amount of time, is there some magical thing that happens that makes it so you can switch to an ASV? Any info you guys may have would once again be appreciated.

[ameriken]

Remember: CPAP does not address central apneas and some of the other breathing disorders. CPAP is mainly for obstructives. ASV is for centrals, other disorders, and obstructives. I'm thinking that if the centrals and other breathing disorders were no longer an issue and there were only obstructives left to deal with, then perhaps one can just go to a straight CPAP. But I don't think an ASV is necessarily a stepping stone, especially if your problem is mostly centrals. ASV addresses the symptoms of centrals and is not a 'cure'.

For example, in my situation, I have relatively few to no obstructives at all so a CPAP doesn't do anything for me. I'm probably going to need an ASV forever assuming that my centrals and other issues continue to stay the same. If my centrals magically go away, then I probably won't need any machine at all since I don't currently have a problem with obstructives.

[Kody]

I agree with you ameriken on this, that is why I thought it was such a strange comment she made. Unless I'm missing something here, I don't see where an ASV unit can "cure" anything, only help you deal with what ever your problem already is.

[justbreathe]

I am using the VPAP ADAPT. There are only three settings on this thing. I am wondering what all the fuss is about special titration and all.

The EPAP is the low setting 10 inches H20 for me. It keeps the airway open and should work just like the cpap.

The PS, Pressure support for me is 3 inches H20. This works like a Bipap and raises to a minimum of 13 IPAP.

The Max PS is 15. This allows the ASV to adjust to a maximum IPAP of 25 inches of H20 when needed to clear an Apnia event. Does not matter if it is Obstructive, Hypopnia or Central in nature. It should get them all.

I don't see why the EPAP would be 10 on the VPAP ADAPT when was doing fine at 6 inches H20 on straight CPAP except for the centrals.

I am not adjusting well to the higher pressure.

Am I missing something and not understanding these settings correctly?

[ameriken]

I agree with you ameriken on this, that is why I thought it was such a strange comment she made. Unless I'm missing something here, I don't see where an ASV unit can "cure" anything, only help you deal with what ever your problem already is.

The only thing I can think of is that person had complex sleep apnea (centrals induced by CPAP) and perhaps the centrals became less and less of a problem and was able to go back to CPAP. Or whatever else was causing the centrals went away and he only needed to deal with the obstructives. Otherwise, the whole thing is ambiguous without an explanation of the situation. I doubt someone could automatically tell all ASV patients that the ASV is temporary and the goal is to get downgraded to a CPAP machine.

[ameriken]

I am using the VPAP ADAPT. There are only three settings on this thing. I am wondering what all the fuss is about special titration and all.

The EPAP is the low setting 10 inches H20 for me. It keeps the airway open and should work just like the cpap.

The PS, Pressure support for me is 3 inches H20. This works like a Bipap and raises to a minimum of 13 IPAP.

The Max PS is 15. This allows the ASV to adjust to a maximum IPAP of 25 inches of H20 when needed to clear an Apnia event. Does not matter if it is Obstructive, Hypopnia or Central in nature. It should get them all.

I don't see why the EPAP would be 10 on the VPAP ADAPT when was doing fine at 6 inches H20 on straight CPAP except for the centrals.

I am not adjusting well to the higher pressure.

Am I missing something and not understanding these settings correctly?

Good question, and I hope JohnBFisher shows up to give you a good intelligent answer, which I think he will!

[Bons]

Have a question about the use of ASV's. Last time I saw my RRT she remarked that another patient after being on the same machine as mine for 18 months was able to go to just a regular CPAP Machine. Like it was a "good" thing to get off the ASV. I commented at the time that I liked my unit because I was able to breath easier with it than a CPAP. Still trying to put this puzzle together, but is it one of the goals to be able to switch down to a regular CPAP Machine rather than stay on an ASV? I know these are much more complicated and expensive, but I thought what ever works for you is what you need. After being on an ASV for a prolonged amount of time, is there some magical thing that happens that makes it so you can switch to an ASV? Any info you guys may have would once again be appreciated.

I wonder how insurance companies would work for that? The only way to get an ASV is to show that cpap and bipap do not help the patient. When I switched doctors shortly after getting the ASV my new doctor wanted to switch me back to bipap but the insurance company said know, even while I was still in a rental stage for the ASV.

[sickwithapnea17]

I think I am getting brain damage from low O2, but I can't get enough therapy or comfort on my bipap st. my settings are 18/14 and on bipap on my graph over the last few months I was getting erratic clear airway apneas. now on bipap st I get hypopneas and rarely obstructives.
I think for years I was getting these hypopneas- I would wake up with rapid shallow breathing and throat congestion
thanks so much!

[ozze_dollar]

Whats the difference between a bi pap and an ASV?

[ameriken]

Whats the difference between a bi pap and an ASV?

The way I understand the ASV, is it basically operates as a bipap machine providing just minimal support while one is breathing normally. However it is monitoring every breath and it builds an algorithm of the breathing pattern. When it detects something going awry in the breathing, then it responds. I've noticed if I stop breathing, it seems to become a ventilator until my breathing starts on my own again. It will maintain my breathing at 10 BPM. When I pick up my own breathing again, the machine backs off. It seems to know when I need a little support, when I need a lot of support, when I need no support, and it responds in kind. That's the best way I can explain it, it follows and matches my breathing.