ASV users: the everything ASV thread.

[ozze_dollar]

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 mainting 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.

Yes I can relate to what you say.

[moresleep]

Whats the difference between a bi pap and an ASV?

Really quite different beasts, although mechanically, a Bipap has the essential quality needed for an ASV--the ability to raise pressure quickly. The rest is more sensors and firmware than anything else...

A Bipap simply provides separate pressures for Inhale vs. Exhale. People who are experiencing centrals with straight Cpap because of the pressure may have less of a problem with the Bipap, because they can use a lower exhale pressure. For more extreme cases, there is the Bipap with S/T, which switches from one pressure to the other at a timed interval, to prompt breathing. The ASV is something like the Bipap S/T but more dynamic. In fact, the Respironics ASV doesn't even have to run in Bipap mode--you can set PS=0, in which case the Enhale and Exhale pressures are the same. (The Resmed ASV insists on a min. 3cm separation.) The ASV uses its analysis of the last several minutes of breathing (or a backup BPM rate) to decide when the patient needs to be prompted to breath. It then delivers a puff of high pressure. If that doesn't work, it delivers another puff, and another one, at successively higher pressures, until the person is breathing again. This type of Auto-Servo-Ventilation is called "non-invasive ventilation" as opposed to true ventilation where the machine would not just "nudge" but would take full control of the breathing.

Both ASV's can be used as straight Cpaps or Bipaps. The Respironics ASV (with which I am most familiar) is actually close to an ideal machine for all occasions, essentially allowing use as a straight Cpap, an Auto Cpap, a Bipap, an Auto Bipap, and/or an ASV, depending on how it is set. At present, of course, ASV machines are hellishly expensive, justifying their placement only with people who need the ASV function. Eventually, though, all Cpap machines, or at least all Bipap machines, may come with all these functions, including ASV, allowing the user to select what is needed...

[moresleep]

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?

I think you've got it right. The Resmed ASV really does not have many settings, and you seem to understand them.

I also do not see any reason 6 cm would not work for EPAP, given that it was enough to prevent obstructive events with straight Cpap--if you're sure about that. In fact, higher pressure generally increases the risk of centrals. If it were me, I would see what happened with EPAP=6. That would give 6/9 cm, plus ASV when needed.

[JohnBFisher]

... 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. ...

Of course, this is sheer speculation, but there are two reasons someone might come off an ASV unit.

The first possibility is that person was improperly diagnosed and/or titrated the first few times through the process (not very likely due to the number of titrations that are normally required for an ASV unit).

The second (and more likely) possibility is that person dropped enough weight and/or had some surgeries that resulted in a lower pressure requirement, which did not trigger the central apneas. The of course assumes they had complex sleep apnea.

The second possibility seems more likely.

I would gladly give up my ASV unit if I could get away from the central apneas. But as long as I have them, I'm glad to have my ASV unit. My objective is to sleep well - regardless of the therapy. If an ASV is what is needed, great. If a ventilator will be needed in the future (a real possibility for me, due the to degeneration of my brain stem) then that's what I would use.

Kody, I agree with you. You use what you need - and nothing more. We don't need a ventilator all the time. But it's nice our units act as one when those central apneas arise. But if we no longer needed that assist (because the pressure was low enough to not trigger central apneas), then going with something less complicated than an ASV unit would be a good thing. Not that I would chase that. Only that it would be good if it was no longer needed. Until then, use what you need to sleep well. I definitely agree with you on that.

[JohnBFisher]

... I am wondering what all the fuss is about special titration and all. ...

Well, done properly they try to find the lowest EPAP setting that keeps the airway open. 10cm H2O seems to be where most of them start, but there is no real reason to have it that high. I assume they started you lower and worked up to 10 where the obstructive apneas were cleared. At least that is how it is supposed to go. Here is the protocol for titrating the older ASV unit from Resmed. I suspect it remained mostly the same for the S9 version of their ASV unit:

http://www.resmed.com/us/documents/1011 ... otocol.pdf

One reason they might have set the EPAP to 10cm H2O is to have the ability to push the maximum pressure upto 25cm H2O. The Max PS goes from 9 to 16cm H2O on the older unit. Thus, 10cm H2O (for EPAP) and 15cm H2O (for MaxPS) is 25cm H2O.

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

Almost. It can act as a CPAP device. In that case the PS will be 0 (zero) cm H2O. There will be no difference between IPAP and EPAP.

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

Exactly. By the way, I find it a little easier if the PS is 4 and not 3. It just separates the IPAP pressure enough to make it easier to breathe.

... 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. ...

By the way, it is centimeters H2O and not inches H2O. One inch = approximately 2.54 centimeters. So, your 25" would be about 63.5cm. Yikes!

It can go UPTO (but may not) 25cm H2O. The actual pressure depends on the amount of air the unit thinks you should be breathing. If it sees that you will fall short, then it ramps up the pressure to increase that amount. It will ramp upto the 25cm H2O if needed. If it does not need that much, the amount it delivers is much lower.

... 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. ...

As I noted, I suspect it was to give you the top end of the pressure.

... I am not adjusting well to the higher pressure. ...

You might want to try setting the EPAP value down to 7 or 8 and see how it does. If it suffice and clears most of your apnea events, then you are probably good to go. Do keep a careful track on the AHI values. If those spike up by dropping the EPAP, then the higher value may in fact be needed.

... Am I missing something and not understanding these settings correctly? ...

Nope. I think you have it.

Hope this helps.

[JohnBFisher]

... 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 "No!", even while I was still in a rental stage for the ASV. ...

Once the insurance companies commit to a higher level of cost, they don't like to back off it, unless it is absolutely necessary.

Bons, I once had a sleep doctor tell me that I had been placed on BiPAP too quickly ... I think he wanted to get into a pissing contest with the other doctor. I simply noted that the sleep study the other doctor used seemed to validate the move. I provided that to the new doctor. He promptly dismissed their work. By the way, this was MANY years ago, when a BiPAP unit costs about what an ASV unit now costs.

So, the new sleep doctor ordered a sleep study. And when we next sat down, the sleep doctor said "Well, you need BiPAP and the pressure has to be increased a bit". He completely ignored me when I reminded him of his earlier comment. He was the same fool that told me I could not have central sleep apnea because it is so rare - regardless of what my sleep study showed.

As you might imagine, he's not my current sleep doctor.

The moral of the story ... sometimes doctors like to prove they can use less expensive therapies than other doctors. Just remember that when the get into these pissing contents you might be their target!

[JohnBFisher]

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.

Exactly. It keeps a moving average of the amount you breathed during the past three minutes. If you fall short (breathe too shallowly or don't breathe at all) it ramps up the pressure to be certain you get enough air into your lungs. This is the adaptive servo-ventilation mode of the ASV unit.

[JohnBFisher]

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!

I've said it before, I'll say it again ... if the BiPAP S/T unit is not working for you ... you need to see your sleep doctor as soon as possible. You've mentioned that you become nauseous and vomit after sleep. These symptoms are NOT normal. In fact, it is very alarming and you should see your doctor immediately. Don't turn to us for further advice, since only your medical professionals should be involved at this point.

[Kody]

... 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. ...

Of course, this is sheer speculation, but there are two reasons someone might come off an ASV unit.

The first possibility is that person was improperly diagnosed and/or titrated the first few times through the process (not very likely due to the number of titrations that are normally required for an ASV unit).

The second (and more likely) possibility is that person dropped enough weight and/or had some surgeries that resulted in a lower pressure requirement, which did not trigger the central apneas. The of course assumes they had complex sleep apnea.

The second possibility seems more likely.

Thanks for your logical response John, once again your wisdom unlocked another mystery question in this unending puzzle.

[Bons]

... 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 "No!", even while I was still in a rental stage for the ASV. ...

Once the insurance companies commit to a higher level of cost, they don't like to back off it, unless it is absolutely necessary.

Bons, I once had a sleep doctor tell me that I had been placed on BiPAP too quickly ... I think he wanted to get into a pissing contest with the other doctor....

The moral of the story ... sometimes doctors like to prove they can use less expensive therapies than other doctors. Just remember that when the get into these pissing contents you might be their target!

Actually, the prescribing doctor was in a pissing contest with me. After two weeks on bipap he said I was doing fine, and I questioned his saying that when my AHI was still over 8. The next day my DME called to tell me to come pick up my new ASV. I spent all of two hours (less than 60 minutes of that asleep) on an ASV during titration, so it remains arguable whether or not I should be on ASV.

[Bons]

Oh gurus of ASV,
I've been wondering for a long time: what is the Ti and what does it to for/to me? My manual doesn't tell me anything about it. For what it's worth, mine is set at 1.

[JohnBFisher]

Oh gurus of ASV,
I've been wondering for a long time: what is the Ti and what does it to for/to me? My manual doesn't tell me anything about it. For what it's worth, mine is set at 1.

From the providers manual:

Ti "Indicates that the inspiratory time setting is being displayed."

And further in the manual for the screen to set the inspiratory time:

7. Inspiratory Time Setting Screen

The Inspiratory Time Setting screen is shown in Figure 6–9. The Inspiratory Time Setting screen displays only if Breath Rate is not OFF or AUTO.

Increase or decrease the inspiratory time by pressing the HEAT and RAMP buttons until the correct setting is reached. You can adjust the inspiratory time from 0.5 to 3 seconds in 0.1 second increments.

NOTE: Th e inspiratory time and breath rate controls are linked so the inspiratory time never exceeds the expiratory time. If the breath rate or inspiratory time are set to values that would cause the I:E ratio to exceed 1:1, the inspiratory time is automatically reduced to maintain a 1:1 I:E ratio.

Hope that helps.

[Bons]

Thanks for trying, John. But what will it do for me? Right now I'm still having the same old issues of the machine switching to inhalation while I'm still exhaling. BPM is set at 6. Rise time is at the max of 6. Ti is set at 1. So, am I correct in thinking that if I move the Ti up to 3 it might help? One of these days I have to find a doctor who is familiar with these things.....

[JohnBFisher]

Thanks for trying, John. But what will it do for me? Right now I'm still having the same old issues of the machine switching to inhalation while I'm still exhaling. BPM is set at 6. Rise time is at the max of 6. Ti is set at 1. So, am I correct in thinking that if I move the Ti up to 3 it might help? One of these days I have to find a doctor who is familiar with these things.....

Bons, you might want to clear Ti to allow the machine to calculate the inspiratory time. Or set it to 5. (5 seconds for inspiratory time plus the same for exhalation equals 10 seconds, which is 6 breaths per minute.

Hope that helps.

[jamiswolf]

Bons wrote: So, am I correct in thinking that if I move the Ti up to 3 it might help?

I defer to John's knowledge on this issue...

But as a general rule, and especially when you're unsure of what you're doing, take "baby steps" Not a radical jump from 1 second to 3 seconds. I believe T settings go down to tenths of a second increments.
Jamis