ASV: Hypopnea Index Remains High

[ozij]

So, Looking at your recent 90% EPAP at 7 and average PS of 3 results. I wonder if you would get similar results by setting Min EPAP at 7 and min PS at 3 or EPAP min at 6 and min PS at 4. In other words set you min EPAP low enough that your unit is occasionally bumping the EPAP up and set you min PS to 3 or 4 to give you a comfortable bilevel range. I'm thinking your min EPAP should be low enough that you should see your machine bumping it just a bit throughout the night. If you have no bumps in the Min EPAP, then it may be too high.

I would consider a week or 2 at EPAP min =7 PS=3, I agree with Mr. Bills analysis. I would definitely use the way I felt as a guide to anything.

I have a question for the two of you or JBF. I understand why min EPAP matters; the titration protocols call for addressing obstructive events by raising EPAP. From what I've read in your other posts, ozij, the ASV only prevents those events -- it does not "cure" them by opening the pathways, and because it takes time for the ASV to make adjustments, those are all reasons you want to set a proper floor for EPAP. (Let me know if I have misunderstood anything.)

It's the PS part that has me a little confused. Let me quote -SWS from another thread (viewtopic.php?f=1&t=60687&st=0&sk=t&sd= ... 05#p574405) where he talks about experimenting with settings to improve AHI:

Here are some of the dynamics you might encounter in an exploratory grid like that:
- as PS Min decreases: a) iatrogenic central events might decrease, but b) primary central events might increase, and/or c) obstructive events might increase
- as PS Min increases: a) iatrogenic central events might increase, but b) primary central events might decrease, and/or c) obstructive events might increase

Here's my question for you: since raising min PS is practically speaking equivalent to raising min IPAP, why not let the ASV figure out the appropriate level of PS?

That's like asking why not trust the ASV's automatic algorithm. One reason is that it didn't seem to work for you. The other is that the machines do not learn from mistakes - they will go down to the minimum again and again, until jogged out of it - and when the minimum (in this case minimum PS leading to minimum IPAP) is too low, you'll be having the events that happen at the pressure the machine reverted to.

At EPAP=7 and PS=3, you're basically enforcing a floor of IPAP=10. What does a higher IPAP floor accomplish?

It keeps away the obstructive events that appear when the IPAP is lower.

from Mr. Bill, you mentioned a "comfortable bilevel range" -- but isn't a higher baseline inhaling pressure going to be inherently less comfortable?

That depends on what you need. Some people feel choked if the IPAP is too low.

And if the higher IPAP is what's required to eliminate the hypopneas, isn't the ASV going to "get there" (and stay there) anyway? Most nights on the ASV, I've seen an average PS around 3, even when min PS is set to 0.

It won't necessarily stay there, and and average does not tell youi how much time you are at each pressure.

In a nutshell, I thought this area was exactly the area where an ASV is supposed to shine compared to conventional treatment modalities like an Auto BiPAP -- so I'm trying to better understand the theoretical background for why applying this particular constraint to the ASV should improve its performance.

The ASV in "out of the box Auto mode" did not work for you at home.

[máirtín]

The ASV in "out of the box Auto mode" did not work for you at home.

I have been following this thread with great interest.
I got the new Resmed VPAP ASV Enhanced about six weeks ago. I am averaging AHI 0.6 over that time which seems to indicate that my central apnea and Cheynes-Stokes is well controlled. But I feel crap every morning - exactly how I have felt for the past 25 years without treatment.
This thread seems to be all about tweaking the settings to get optimal AI and AHI results. Don't get me wrong, I think that is important. But I would like to see more information about tweaking the settings of this new kind of machine so that I actually feel better.

[Mr Bill]

So, Looking at your recent 90% EPAP at 7 and average PS of 3 results. I wonder if you would get similar results by setting Min EPAP at 7 and min PS at 3 or EPAP min at 6 and min PS at 4. In other words set you min EPAP low enough that your unit is occasionally bumping the EPAP up and set you min PS to 3 or 4 to give you a comfortable bilevel range. I'm thinking your min EPAP should be low enough that you should see your machine bumping it just a bit throughout the night. If you have no bumps in the Min EPAP, then it may be too high.

I would consider a week or 2 at EPAP min =7 PS=3, I agree with Mr. Bills analysis. I would definitely use the way I felt as a guide to anything.

I have a question for the two of you or JBF. I understand why min EPAP matters; the titration protocols call for addressing obstructive events by raising EPAP. From what I've read in your other posts, ozij, the ASV only prevents those events -- it does not "cure" them by opening the pathways, and because it takes time for the ASV to make adjustments, those are all reasons you want to set a proper floor for EPAP. (Let me know if I have misunderstood anything.)

It's the PS part that has me a little confused. Let me quote -SWS from another thread (viewtopic.php?f=1&t=60687&st=0&sk=t&sd= ... 05#p574405) where he talks about experimenting with settings to improve AHI:

Here are some of the dynamics you might encounter in an exploratory grid like that:
- as PS Min decreases: a) iatrogenic central events might decrease, but b) primary central events might increase, and/or c) obstructive events might increase
- as PS Min increases: a) iatrogenic central events might increase, but b) primary central events might decrease, and/or c) obstructive events might increase

Here's my question for you: since raising min PS is practically speaking equivalent to raising min IPAP, why not let the ASV figure out the appropriate level of PS? At EPAP=7 and PS=3, you're basically enforcing a floor of IPAP=10. What does a higher IPAP floor accomplish? Mr. Bill, you mentioned a "comfortable bilevel range" -- but isn't a higher baseline inhaling pressure going to be inherently less comfortable? And if the higher IPAP is what's required to eliminate the hypopneas, isn't the ASV going to "get there" (and stay there) anyway? Most nights on the ASV, I've seen an average PS around 3, even when min PS is set to 0.

In a nutshell, I thought this area was exactly the area where an ASV is supposed to shine compared to conventional treatment modalities like an Auto BiPAP -- so I'm trying to better understand the theoretical background for why applying this particular constraint to the ASV should improve its performance.

As always, thanks for your time and help.

For me, the first few months I had this visceral fear of falling asleep made worse by having the mask on and feeling like it restricted my inhalation. It took me 3-4 months to get over that gut level fear. That fear made my breathing excited and I felt like I was starving for air. I would suck hard every breath and finally somehow fall asleep. Gradually, I figured out that getting calm first made the breathing better. Also, I quickly figured out that my ASV responds to holding my breath by bumping up the PS to higher values and then gradually ramps them back down. So, there was at least a few months there where I would hold my breath a few times on purpose to bump up that PS so I did not feel like I was sucking vacuum. But over time now, I just get calm quickly and then breath along with the timing. My min PS of 3 is just enough difference to me that I can feel that little assist when I start to breath. My minute vent and BPM numbers always start out around 15 (a liter per breath) but then when I fall asleep the ASV catches me and I perk along at a minute vent of 9 and BPB of 18 (half a liter a breath).

As you can see my EPAP is 6 and Min PS is 3 which I guess is that low because I have such a problem with centrals and they get worse as the pressure goes up. Both bump up by about 1 unit when I am sleeping. So, I guess I am right where I ought to be.
viewtopic/p601542/viewtopic.php?f=1&t=4 ... 72#p568572
For some odd reason (I've asked SWS about this) sleeping on my back gives me the best sleep. I guess my 90% EPAP of 7 and avg PS of 4 takes care of that. Either side and the hyponeas jump right up.

So, to actually stick to the point and answer the question. I am guessing the EPAP is about what you need to keep a clear airway when you exhale. PS must be needed because exhaling is easier than inhaling and that PS makes the difference of that little bit more pressure to open the airway for inhalation. I guess us ASV breathers want to keep those numbers as low as possible to reduce centrals but high enough that the ASV is not hunting all night fixing up OSA. I have mild asthma and I can always tell I am going to have a higher AHI night because my mouth gets dry even though I am drinking lots of water and my tongue seems bigger so I am biting the edges a bit and swallowing becomes slightly difficult.

[Bons]

Hey BrianinTN, what did your doctor set you up with for an 'Inspiratory Time'? I noticed you have a pretty high BPM, around 17. As you see in my sig, they set my I.S. at 1.2 seconds. I was wondering if that is why my BPM ends up being 17-19? Does everybody breath this quickly when on ASV?

My RT called tech support at Phillips/Respironics today to figure out why the pressure shimmies when I'm breathing and awake. What she was told is that the ASV gives everyone 3 seconds to inhale and again to exhale. So when the rise time/inspiratory time is set at it's highest, it still expects you to breathe at least ten times per minute... if it's set lower it expects you to breath even faster. That's why my long, deep breaths drive the machine and me crazy.

[Mr Bill]

Hmmm, I am going to ask my RT if I can try a longer inspiration time.

[BrianinTN]

On my BiPAP titration they had me down for an inspiration time of 1.8, but the doc didn't include that as part of the prescription. So, when the DME programmed the machine, they put in 1.0. Bumping that up made all the comfort difference in the world.

[Bons]

My RT spoke with the tech support at Respironics and they came up with the theory that slow breathers like me tend to be incompatible with the ASV. It wants me to breathe faster than I want to breathe. They suggested that I turn the rise time setting at its highest (6), which makes the slowest transition from EPAP to IPAP. Felt much better last night and I fell asleep quickly and stayed asleep, save for a few leaks/mask adjustments.

Which helps me to understand what happened to make my titration for the ASV so miserable. I picked up my report yesterday (amazing what a call to the medical society can do after 6 months of requests to the doctor's office). I had told the tech that the machine was "fighting me" and "making me feel like I was hyperventilating" - her notes in the report, and true. Her response was to turn the rise time to the lowest setting, which actually speeds up the transition time, so of course I "continued to express frustration and difficulty breathing", leading to the discontinuation of the ASV and a switch back to BiPap.

[máirtín]

They suggested that I turn the rise time setting at its highest (6)

What is the "rise time". How do I set/change it on my machine?: ResMed VPAP ASV Enhanced

OT: Is the ResMed VPAP ASV the same as the ResMed S9 VPAP ASV?

[JohnBFisher]

They suggested that I turn the rise time setting at its highest (6)

What is the "rise time". How do I set/change it on my machine?: ResMed VPAP ASV Enhanced ...

"Rise Time" is the time it takes for the machine to switch from exhalation to inhalation. Without that, it would be a sudden pressure switch from one to the other. With a longer "rise time", it allows the pressure switch to gradually occur, which tends to allow slower breathing.

On the ResMed VPAP ASV Enhanced, "to gain access to the Clinical menus, press the Right and Up/Down keys
simultaneously for 3 or more seconds".

OT: Is the ResMed VPAP ASV the same as the ResMed S9 VPAP ASV?

They are both made by ResMed, but they are different machines. The VPAP Adapt SV Enhanced unit is based on an older S7 body. The S9 VPAP Adapt SV unit is based on the S9 body. However, since they use very similar electronics and algorithms, the settings are very similar.

[Edited to add the response on Rise Time.]

[ignorant1]

Just a quick note to help anyone searching this thread in the future: The S9 based ASV model ("S9 VPAP Adapt") does NOT have a rise time adjustment in the clinical setup menus, whereas the older resmed model does have it.

[máirtín]

Thanks for the info, John!

[Jay Aitchsee]

Brian, Hi. Wow, what a thread! I'm not an expert, nor a medico, but I have suffered from disturbed sleep for more than 10 years and like everyone else I've been searching for the magic bullet that will give me that refreshing sleep we all want. Let me throw a few things out there for your consideration.

First, let me say that I have no idea what half the variables are that your machine is controlling, I'm working with a basic S8 auto. I can tell you this, though, if I give the machine full range, I feel like crap, even though my numbers look good. When I narrow the operating band, i.e., raise the min pressure, lower the max pressure, I feel much better, even though the numbers (AHI) are basically the same. Likewise, when I use EPR (CFlex), I feel like crap, still good numbers, though. As others have said, I think you should try to limit the numbers of variables you are changing to one at a time and let it run for a while (week?) and see what happens. I'd be tempted to run in the straight CPAP mode set at your best guess of effective pressure and work out, rather than in. Remember, I'm just throwing stuff out there. I read your reasons for the auto bipap.

Have you given any thought to the fact that you may have more than one problem? Your titration looked excellent, from a respiratory point of view. It's not in front of me right now, but I don't think you had any respiratory arousals. On the other hand, you had 90 LM arousals in 6 hours. Thats an index of 15. Still, you seemed to be getting to stage 3, so... ? Do you have a neurologist certified in sleep medicine on your team? If not, I'd consider finding one. My experience has been that once pulmonologists have apnea under control and the patient still isn't experiencing refreshing sleep, they have nothing else to offer.

What about meds? You mentioned clonazepam in one of your posts. I believe that's a CNS depressent and I question its use if you have CSA. Additionally, it is my understanding that although clonazepam is a very effective sedative it does not promote stage 3 sleep. As far as the ambien, I would consider halving that 10 mg to 5 (break the pill). I find that too much (10 mg) ambien gives me a druggy hangover. A technique I've read about is to take a minimal amount of ambien at bedtime and if you wake up in the night, take a little more; like 5mg at bedtime followed by 2.5 if you wake. Quite honestly, I've tried this and couldn't get it to work. I've tried the 6mg CR Ambien too, also gives me a drug hangover and since it's a time release capsule you can't split it. There was a mention of Ibuprofen in one the posts, I'm not sure whether it was yours or not. Oddly, if I take Aleve at bedtime, I get that same drugged feeling in the morning. I'm just saying....

Brian, I hope you take these comments as they were meant. Just observations on my part, something to think about on yours. Sometimes looking at things from a little different angle helps.
I wish you all the best,
Jay

[BrianinTN]

Thanks for weighing in, Jay. I definitely appreciate the suggestions. To hit most of your points, although not in order:

* My doc right now has his specialty in pulmonary, and I'm scheduled for a follow-up with him mid-month. Your suggestion that someone with a neurology background seems spot-on and is what I've been thinking as well. I'm planning to see another local sleep doc who has an excellent reputation and a neurology background. I figure more input is a good thing, and since I'll just be out my copay, the price is right. If there really is more than one problem going on, that's the best way to figure it out.
* Changing settings: I have been trying to keep things constant for several days at a time. Unfortunately, so far, I've yet to find anything that consistently yields both a quantitative and qualitative improvement. I took a nap two days ago without the ventilator, and while I wore it that night, when I woke up the following morning I went back to sleep without it. I felt so much more rested and wonderful not using it. I know the common advice is to encourage patience, but in my case, I've been on one ventilator or another for the better part of a year now. I don't feel like this is an issue of me getting "used to it."
* Meds: I've set aside the clonazepam almost completely, although my understanding is that it can actually help with central apneas and PLMD. Nevertheless, that's not really the med I want to get dependent on to deal with those problems. As far as the Ambien goes, I had initially started with 5 mg a couple years ago but had to bump it up to 10 mg about a year ago. My body seems to build up a tolerance to it, which is why I switch back and forth between it and Lunesta (to which I build a quicker tolerance). I wish I didn't have to take any of these things, but my insomnia is just bad enough to make sleep nearly impossible while on the ventilator without them. Anyway, I kind of like your idea about splitting the tablet and taking a little more when I wake up -- I'll give that a shot tonight.

An addendum I've been meaning to add to this thread has to do with my "old" titration results. A lot of the thinking is that giving the ASV free reign has me starting at a pressure that's simply too low. I should have done it earlier, but this is the table from my BiPAP titration:


What's most interesting and perplexing to me is that the pressure increases by the technologist were not done to treat obstructive apneas; they were to treat centrals predominantly, and then hypopneas. As -SWS had explained to me in my BiPAP thread a while back, we can't be sure whether hypopneas are obstructive or central in nature, but here I actually don't think that matters since the ratio of centrals to hypopneas is high for the first four pressure settings they tried, ranging from 10/6 to 13/9. Throughout the entire night, I didn't have a single obstructive apnea at any pressure setting. Granted, the brief duration at each setting means that there is no guarantee that an obstructive event wouldn't have occurred at that setting given enough time, but still...

What does this mean practically for me? I don't know. Maybe some of you folks do. But at least in the BiPAP titration, the pressure increases weren't to address obstructive apneas. I have a call into my nurse to get my full PSG results from all four of my studies, as I'm eager to see what the table in my initial CPAP titration looked like too.

[BrianinTN]

As I saw a new sleep doctor who specializes in neurology today, this seemed like a good time for an update and maybe some fresh advice.

For the past month, I've reverted back to min EPAP=4, which seems to work well. For the most part, the ASV keeps my EPAP around 4-6 and rarely goes above that. It seems my obstructive apneas don't require much pressure. Experimentation with higher values of EPAP did not improve my residual hypopneas.

Experimentation with min PS also yielded no effect on the hypopneas. I am now using a nasal pillow mask (Swift LT) on some nights, upon the advice of my PSG-tech friend. While min PS=0 is perfectly comfortable with my FFM (Fisher & Paykel 432), I sometimes feel like I'm suffocating with my mouth taped on the Swift LT. As such, I've generally found it to be more comfortable to go to sleep with min PS between 3 and 5. So far, PS has been a comfort settings, and changing its value has not had any quantitative clinical impact.

My new doc feels like my data generally look good. There are enough nights with AHI<5 that the nights where AHI>5 don't worry her too much. However, she is concerned about two things I said:
1) I feel worse when using my ASV compared to using nothing at all.
2) I require a sleep pharmaceutical (e.g., Ambien or Lunesta) to get to sleep on the ASV, but don't require that when not using it

As such, her belief is that I may simply be one of those people who is intolerant to pressures, even at such low values, and that may be exacerbating another underlying problem.

The PLMD is a potential culprit here. She first mentioned the possibility of trying Gabapentin (Neurontin) replacing my other sleep aids as well as the Mirapex/Requip to treat the PLMD. However, I started taking Remeron recently, and because she doesn't want too many prescription changes going on, we're going to leave that side alone at least for the time being.

To deal with (and test) my possible intolerance of any air pathway pressures, I am now scheduled for a consult with a dentist, the expected outcome of which is an oral appliance. I have TMJ, so I'm used to using a mouthguard (although to be frank, my compliance with it has been horrible).

Whee, it's been a fun month.

[Paper_Nanny]

The PLMD is a potential culprit here. She first mentioned the possibility of trying Gabapentin (Neurontin) replacing my other sleep aids as well as the Mirapex/Requip to treat the PLMD. However, I started taking Remeron recently, and because she doesn't want too many prescription changes going on, we're going to leave that side alone at least for the time being.

Yes, one change at a time is usually the best strategy with medication changes.

Is the suggestion of replacing the other sleep aids with neurontin because it has sleepiness as a side effect or for a different reason?