CPAPtalk.com

christinequilts wrote:I don't buy that CPAP intolerance is playing more of a major role then use of a non-approved mask, especially when you take into account my history with various machines, complexity of my CSA and lack of adequate control of my centrals & periodic breathing with other machines. It honestly did not feel like I was using my Adapt and if I didn't know any better, I would have said someone hooked me up to a different machine, by the way it acted was so dramatically different. If it did that with a regular mask, my DME would have gotten a call in the middle of the night to replace it immediately. It was not functioning within normal parameters.

LC is integral to the function of the Adapt. They don't have us do it just because, it is so the machine can function properly. I pulled on my clinical manual and here is what is says (sorry for any typos):

From the Clinical Manual:
Learn Circuit
The Air Circuit Learn function (LEARN CIRCUIT) provides a way of factoring the impedance of the air tubing assembly into the the delivered pressure. The Air Circuit Learn function must be run every time impedance in the air circuit is altered (eg, addition or removal of an antibacterial filter or addition or removal or a humidifier), or the flow generator is moved to a significantly different altitude. Set up the whole system (flow generator, air tubing, mask and other component) before running LEARN CIRCUIT. Do not cover the mask. If the LEARN CIRCUIT fails, the VPAP Adapt SV reverts to the last successful impedance value.


And from the User Manual:
The Air Circuit Learn function takes approximately 20 seconds to run. It allows the unit to 'learn' what pressure it needs to build into its calculations, based on the components in the system. Select LEARN CIRCUIT every time you add or remove a component (eg, mask, humidifier) or move to a significantly different altitude.
To run this function:
1. Set up the entire VPAP Adapt SV system (flow generator, mask, humidifier, etc) as you wish to use it.
2. Make sure that the mask is unobstructed so air can flow from the mask to the flow generator.
3. Turn on the VPAP Adapt at the power switch.
4. Move through the menus until you reach LEARN CIRCUIT and select 'yes' by pressing the Left key.
5. A message will remind you to check that the airflow from the mask is clear. select 'start' with the Left key.
6. A progress screen is displayed while the Air Circuit Learn function is running.
7. When the function is complete, a screen will appear saying that the circuit has been learned successfully. The next menu item item is then displayed. Commence treatment...
If there is a problem with the circuit a screen saying 'Invalid Circuit' will be displayed instead of the progress screen. Check that all the connections between pieces of equipment are secure. You may need to return to the previous chapter of this manual to check that you have set the system up correctly.

So I don't think there can be any question about the LC and how important it is to use masks & components that pass the LC. By putting the Swift on, after running LC with a Vista, the impedance is clearly changed by the smaller diameter mask tube and the restriction of the nasal pillows themselves. I won't list all the various mask I have tried with the Adapt, but anything that has a smaller diameter mask tube will not pass, like the Dream Seal, Simplicity, or ComfortLight with the over the nose attachment, even though the mask part itself is relatively open. Mask like the Comfort Select and Comfort Gel with direct hook up to the hose and no major restriction on airflow pass the LC fine, using a similar listed ResMed mask selection, though each person still has to decide on their own if using a non-approved mask is appropriate through trial and error.

Looking up 'impedance' in the dictionary and you get a lot of stuff related to electricity & such, I'll leave that to the engineers. My basic take on it is that say I plan a quilt top with standard 1/4 inch seam allowance (impedance), with 40 seams across and 80 seams down that is suppose to be 50"x70", simple enough. But when I sit down to sew, I accidentally used a 1/3" seam allowance, because I changed the presser foot (Vista=1/4", Swift=1/3") after I ran all the calculations & planned everything (ran Learn Circuit). Suddenly my 50"x70" quilt only measures 43.6"x57.2"...and someone is going to have cold toes. If something as small as the difference between 1/4" & 1/3" can make that much of a difference when compounded by multiple seam allowances, think about all the calculations the Adapt is performing every second...and if the calculated impedance is off, all its calculations are going to be wrong, from Tidal Volume to BPM to Minute Vent to Target Vent to Leaks, Mask Fit, Median Pressure, etc. Would you want to use your APAP if someone reprogrammed it with different numbers?

StillAnotherGuest wrote: I think the volume and pressure measurements should be OK, I don't believe Learn Circuit has any bearing on that. But if this thing works chiefly by a component of PAV, if you make it think that there's more resistance in the circuit than there actually is, then what you got now is a REAL expensive BiPAP that has a mind of its own. And it's not gonna think what you want it to think.

I don't know...I have to question any measurement when the machine wants to give me IPAP when I'm exhaling and EPAP when I'm inhaling. It wasn't like that all the time, but enough of the time to make me question any numbers it reported. I still couldn't get over how easy it was to hold my breath with the Swift on for several breath cycles, as I've never been able to do that with my Adapt...mind of its own? it didn't even know its own mind, IMHO.
Edited to add...I guess what I'm saying is the pressure numbers may be correct that the machine reports, but I feel the use of the Swift screwed too much with the Adapt's reading of what pressures I needed compared to normal functioning. Clear as mud?

My Swift has found a new home with my Mom for now...it was either that or it was going to become a cat toy. And I'm sticking with my Vista & Activa with my Adapt for now. This whole experience has reinforced how important LC really is and I'll do my best to remember to run it, even when I have to switch masks at 3am.

Hey Christine:
You didn't by any chance get the software, or can you get the machine downloaded at the DME and grab the file? The download has only the last maybe 3 days of complete data, but you can look at long term trends for the rest of the period. A real bad night should stick out.
SAG

Wow - in a few days, there are certainly a lot of material covered.
I'd make the "ya snooze, ya lose" analogy, but somehow it doesn't fit a sleep apnea blog.

The engineer in me looks at Learn Circuit as a process that compensates for the tubing, humidifier air and water space, mask. The LC takes out the effect of the tubing, et al on the algorithm. Obviously it makes a difference or ResMed would not have bothered to add it to the design.

I like Christinequilts description - it is quite clear.

For me, impedance is the resistive component that otherwise impacts how well current will flow in a wire or coaxial cable. There is a spot where it works best for a particular use - which is why antenna cable of a certain impedance value in ohms is used. You also like to "match" the output of an amplifier circuit to the load for optimum values. That is how I see the Learn
Circuit function.

This is an analogy for me, not necessarily a completely accurate description of how it works. It's just how I think of it.

BTW, thank you several days back for clarifying the ASV "mod" to include indices. Now the comment makes sense.

A search of the http://www.fda.gov web site, for new ResMed requests, will show when the revision is approved in the USA. Eventually one regarding the change will be posted when it is approved.

What I want to know, is the pressure sensing tube, that is located "as close to the mask interface as practical" -- when one uses EERS, and moves the pressure sensing point further away from the mask -- what does that do to the machine performance?

See the fun you miss out on! I hope FQ finds her way back soon too.

Lubman wrote:
What I want to know, is the pressure sensing tube, that is located "as close to the mask interface as practical" -- when one uses EERS, and moves the pressure sensing point further away from the mask -- what does that do to the machine performance?

You know I've wondered about that too, but with the Activa & Vista its further away too because of the mask lead hose. Shhhh! Don't tell, but I've left the lead hose on a few times when I've used my UltraMirage nasal and UMFM (which I try to avoid using at all cost)...that cuff thing is a bit annoying at times when it hits part of the anatomy you guys don't have to worry about...let's just say with the UM or UMFF, it can make turning your head dangerous I've also wondered about using it with the pressure sensing tube hooked up to one of the O2 vents on various masks, but then you're putting more variable in again.



I've got to hope getting my allergies under control better helps control my dermatographism & pressure urticaria, or I'm going to run out place on my nose to park mask that will work the Adapt. I still have my Synchrony ST & BiPAP STD, but I have no desire to use them even for a couple nights. I guess it could be worse...at least I can get away with wearing makeup to cover the red, raised welts easier then a guy could

Hi Everyone -

Good activity here. I think the range of questions, ideas and information is going to be very helpful in contribution to the interaction with Beth Israel. In other words, I am going for my sleep study there tonight, and will bring a printout of the last couple of pages where the discussion has gotten down to the brass tacks I was hoping to elicit from you brilliant folks!

About the Swift, I will just say again that the BI people said they tested it and it was successful and equivalent. That is why I have maintained my use of it. But I am going to be very interested to see the response to questions raised here. I have an open mind about all of it, the Swift question, whether ASV is right for me, the backup rate question, the discomfort during the initial patient callibration, etc.

I am hoping we will investigate these points during my study tonight with all the facilities available to get as much factual data as possible.

If you have any further suggestions or questions please post asap and I will bring those in too!

Thanks again,
frequenseeker

Good Luck FQ!

I will be very interested to hear what they have to say about the Swift too. Seriously, have them try it after running LC w/Vista, keeping it on for at least 5-10 minutes, as you were instructed to yourself. Then have them run LC w/Vista again, or any other approved mask and use that mask for the same amount of time. I'd like to even hear your experience doing the same thing and see if notice the difference in comfort level, I think you will find it much more comfortable.

I know you don't have any real experience with BiPAP ST to compare the Adapt, which may very well be the case for many of its users who have been switched from CPAP or regular BiPAP and many may think 'that's the way its suppose to feel,' when it isn't. You should never feel like its fighting you or trying to push you around, that's just not how ST work, unless you are using them in straight TIMED mode only of course, which is what I feel the Swift may be inadvertently causing the Adapt to do. Wasn't your BPM range fairly tight around 15 when they downloaded the data? What about what the machine reported RR every morning? Which is actually the 5th and 95th percentile, so we know it drops obvious outliers on both ends. Mine is fairly constant at 11-16, 12-17, etc. I think my 3 months average is something like 12-18, but I have had as high as 12-20 for a night or two- much different then what you are reporting. I can't compare my Adapt numbers as easily with my Synchrony, as it reports highest & lowest RR per whole minutes, so those times I had minute long apneas gave me a range of 0-17 BPM, where other nights I would generally had a range of 11-18 or so, if we dropped the outliers.

You also mentioned in a post to DSM a few days back your MV was 2-4:

Your MV ...Mine BTW is 2-4 on the onscreen stats, which is all I can get at the moment

March 28
How did that compare with data from your VPAP III? Just to compare, my MV is in the 3-7 range consistently (5th & 95th percentile again), which is within range of what my Synchrony use to show, when I drop the nights 60 second plus apnea nights. Of course I'm not certain how reliable the Adapts data can be with the Swift in circuit, but if you have a RR of 15 & a MV of 2-4, there are only so many possibilities for TV, as MV is a measure of both RR & TV. How did that compare with your VPAP III?

I'm still a little confused about your misunderstanding of the backup rate of 15, and even more so of your doctors. ResMed made that fact very clear at all stages of development, from the very early days of CS2. I believe many others on this post will remember the BR of 15 was a major concern I raised in relation to myself several times in particular, long before the first VPAP Adapt SV was ever released in the US. I was much happier when marketing information, especially the technical data sheet at ResMed.com explained it well enough for me to understand its not a fixed backup rate like a normal ST has, but rather a 'when all else fails' and it doesn't have enough information about my recent breathing rate to try to get me breathing again backup rate. Maybe instead of calling it a 'backup backup rate' as I suggested earlier, failsafe backup rate would be more appropriate? And since I've never seen any of your PSG reports mention central apneas, under normal circumstances, I do not think the failsafe backup rate of 15 would come into play. What do others think?


IMHO, I think it would be good for you to at least have a split night PSG, with no intervention the first part of the night at all. How long has it been since your original PSG? 3 years? With as much difficulties as you have had with various CPAP, BiPAP, and now the Adapt, you do have to wonder what is really under all those layers of complex treatment. As a nurse practitioner, I'm sure you've had patients come to you taking vitamin supplements to counteract medications for GERD, which they were taking to counteract the NSAIDS they were taking for a sore shoulder that has long such healed. Do you tell them to keep taking everything they are taking and give them something else for the diarrhea they now developed from taking the vitamins and continue to possible treat side effects instead of the original symptom? Or do you work with them to find out if that shoulder injury did heal or at least look for alternative, safer, less complex, and less likely to cause other problems to treat the shoulder if pain persists then NSAIDS?[/quote]

So, FS --- tell us how the study went?
I think we are all curious about any initial results

Lubman

christinequilts wrote:See the fun you miss out on! I hope FQ finds her way back soon too.

Lubman wrote:
What I want to know, is the pressure sensing tube, that is located "as close to the mask interface as practical" -- when one uses EERS, and moves the pressure sensing point further away from the mask -- what does that do to the machine performance?

You know I've wondered about that too, but with the Activa & Vista its further away too because of the mask lead hose. Shhhh! Don't tell, but I've left the lead hose on a few times when I've used my UltraMirage nasal and UMFM (which I try to avoid using at all cost)...that cuff thing is a bit annoying at times when it hits part of the anatomy you guys don't have to worry about...let's just say with the UM or UMFF, it can make turning your head dangerous I've also wondered about using it with the pressure sensing tube hooked up to one of the O2 vents on various masks, but then you're putting more variable in again.



I've got to hope getting my allergies under control better helps control my dermatographism & pressure urticaria, or I'm going to run out place on my nose to park mask that will work the Adapt. I still have my Synchrony ST & BiPAP STD, but I have no desire to use them even for a couple nights. I guess it could be worse...at least I can get away with wearing makeup to cover the red, raised welts easier then a guy could

Hi everyone -
I had a great sleep study...I think! Have to see what the report says really happened
I wrote all about it to post, then lost it so you'll have to wait a little bit more to hear. I will try to post again within the next day. A bit busy at the present.

Back soon...
FQ

StillAnotherGuest wrote:
There were criteria/recommendations that were given us at ASV start-up:

Indications
CHF NYHF Class III/IV with LVEF <40%
+/- Atrial fibrillation
pCO2 <38 mmHg
CSR by history or PSG
Cyclic hypoxia

Contraindications:
Chronic hypoventilation
Moderate-to-severe COPD (pCO2 >45 mmHg)
Restrictive thoracic or neuromuscular disease

We have added:

Central-oriented AHI refractory to traditional pressure therapy

to address CSBD.

The concept of using ASV for everything is VERY recent, hence my earlier comments, which I still stand by. There's "approved uses", "anecdotal evidence", and "hybrid mask" philosophy.

Approved uses vs really working?- how has that proven out over time? Or was it more a case of the Adapt was 'approved to treat all forms of CSA', just as all BiPAP ST's are, since the Adapt is technically still a BiPAP ST, and therefore all BiPAP ST could have made the same marketing claim ResMed made? You know my experience with it- LOVE IT- but wondered about how its looking from your point view as a sleep professional?

How have your centers' indication for when to trial ASV change since last summer?- if they have, of course...just figured they probably have with more hands on experience, even if there hasn't been any peer reviewed research on non-CSR/CHF patients yet.

Also, what is the general refractory AHI range for CSDB diagnosis? What do you think about the Medicare requirement of an AHI of 5+ residual centrals with for CSDB and therefor qualification for treatment with BiPAP ST or ASV? Couldn't an overaggressive titration or using BiPAP when not indicated cause that many centrals per hour in some people? And what would happen if someone is put on ASV if they don't need it?

StillAnotherGuest wrote:OLT, the concept of ASV has similarly been around a while, under a variety of names. It might be a good idea to start out with the basic concepts of ASV, and then we can apply this to what these "servo" machines pick and choose:

Adaptive Support Ventilation
• If no spontaneous effort to breathe, machine delivers required minute ventilation (VE) as pressure control, comprised of pressure support (PS) and rate (f).
• If patient starts to breathe spontaneously, machine reduces f and lowers PS to keep VE above set minimum.
• If spontaneous tidal volume (VT) is > target and f <target, PS is reduced and f is increased.
• If VT > target and f > target, PS is lowered and f is reduced.
• If VT < target and f > target, PS is increased and f is lowered.
• If both VT and f are < target, machine increases f and PS.

So that's what its busy doing all night Scary to admit, but that makes perfect sense to me now after 5 months with my Adapt. Tempted to use it to better explain what it does, adding my observations as an end users...I do better with 'if you don't breath deeply enough or quickly enough, it does..." then VT < target, then PS... personally (though my GRE scores indicate otherwise...I still think they got my analytic scores mixed up with someone else's-lol)

Back again..extenuating circ's and then a bad cold...

So this is how it went (I don't have the formal report yet):
I presented excerpts I had put together from the comments on this topic to my BI doctor.
I asked questions of my PSG tech.
He explained that the only way to identify problems and solutions is through challenging during the PSG. By giving more or less pressure, cpap/bipap/etc., looking at O2/CO2 during challenges..etc.
The doctor was consulted with before and during the study (even at 1:30am).
He started with the ASV. After a couple of hours I woke with anxiety, churning stomach, chills even though the room was very warm (when I was awake in the am I could easily verify that), couldn't go back to sleep and became aware that the higher rate of breathing was related to this. After an hour and a half... I called the tech in and explained that it was not going to work like that.
He called the doctor and returned to say we were going to switch to bipap. I still had chills and trouble falling asleep, not sure if it was just going to take time to get it to settle down.
Then the tech came in again and increased the tubing for more CO2 (EERS). A few moments later, I suddenly got nice and warm, relaxed, and fell asleep until he woke me for finishing up.
Though I had not had many hours of sleep, the tech had awakened me guided by my being at the shallow end of the sleep cycle, before I went into the deep stuff again. This helped me feel fairly good, and I had a very productive day following.

My doctor has also told me:

Basic reason for the limited masks for use with the device is that mouth leak will compromise the adapt performance and the decision was made to recommend the device with full face mask as that would be expected to have minimal leak issues. Basically if flow through the leak (mouth or other) is excessive, targeting a volume by changing pressure becomes futile because flow through the leak is “infinite” and will compromise the algorithm. If leak minimized with a nasal mask then should have a capacity to perform—makes is more of an off label use rather than black box warning as is suggested (by the topic posters). If you’re fine with the Vista and awful with the swift I would want to know what the leak was—that would explain a lot.

Having talked with with the Medical Director from ResMed:

the back-up rate of 15 is really a set parameter and can not be modified. It is relevant across the night and will not let you breathe at a lower rate. They designed it for CHF patients who on balance are tachypneic and breathe faster than that. Future devices may allow us to modify that but in its current form there is no way to get the resp rate <15. ...last night during the study it really sounded like that back-up rate is creating problems for you during the night--suspected based on the at home data and confirmed in the lab--will have final thoughts when I can see the primary data but I worry the Adapt really may not be long term good in its current form if it is always going to be trying to overdrive your ventilation. That EPAP max of 10 is again fixed--I think it is going to leave you slightly under-supported in REM. Therefore the pattern of arousal due to inadequate pressure--confusion of the ventilatory control with a high back-up rate prohibiting return to sleep may be hard to break with the current Adapt.

I am currently using my VPAP III on cpap mode and pressure of 11. It helps me through most of the night, but that early morning switch to dreaming continues to be a challenge as the cpap pressure is not very effective for that apnea.

My sinus cold has been a challenge too, couldn't use the pap very much last night, but am on the mend with antibiotics now.

Latest thought out of BI is that they are investigating the new Respironics Bipap that has four different modes, including one that is like ASV. This might be an option for me.
I'm starting to imagine a setup where I am on one machine until 4am and then have to switch to another to get through the REM apneas Oh well, you can get used to just about anything, if it makes you feel better...
Hey, I could try this at home, kids: use the ASV for cpap mode for the first part of the night, then switch to the VPAP III on higher pressure bipap to finish it out...have 'em set up side by side, etc. No problem, I am used to fiddling with machines and masks and going back to sleep. But to have to drag two machines when I travel every week??!!

frequenseeker

Frequenseeker, thanks for reporting in!

Absolutely no disrespect to your doctor. But that first quoted answer about masks raises plenty of confusion in my own mind. There must have been some kind of disconnect between question and answer, to account for what seems like a bit of an illogical answer to me. The original question pertained to the Swift failing ASV's Learn Circuit, and whether there were any treatment ramifications for failing that impedance-based pressure calibration routine using the Swift.

But I don't understand the answer relative to that question. It simply says there were limited ASV mask choices because the ASV algorithm is so leak sensitive. And since leaks through the mouth are bad to the ASV algorithm, a decision was made to go with a Full Face mask. Here's where I get really confused: Three of the four ASV mask choices on the menu are nasal only masks, right? So that's obviously not what your doctor was talking about.

But to continue my own perception of illogic relative to the ex-lunation. Those three nasal-only choices all pass the Learn Circuit routine on the ASV with flying colors. Yet the Swift cannot pass the Learn Circuit routine. But that sends us back to the original questions unanswered: What are the treatment ramifications, if any, of Learn Circuit failure with the Swift? And if there are no ramifications, then why is the calibration procedure that always fails with the Swift placed documented as a prominent step? Regardless, thank you very much for conveying the answer that you received, Frequen.

That second quote from the Resmed medical director gives a simple, clear, and extremely helpful answer IMO. The back up rate is fixed at 15. That answer is simple and it helps immensely IMO.

I have the above answer in bold, red text, because it's contrary to the impression I get reading the Resmed Fact sheet as well as the very promising marketing literature. But it looks like ASV entails at least two treatment characteristics that are not at all well-suited for you according to Resmed themselves: 1) fixed 15 BPM back up rate, and 2) EPAP Max of 10 cm.

So back to the VPAP III. I distinctly recall reading a few years ago when you first discovered using the VPAP III easily your own spontaneous breath rate hastened with nothing more than a higher experimental back up rate. Here we are once again with what seems to be RR skewing based either primarily or exclusively with a higher BR. It sounds as if you need more BR flexibility.

The Respironics BiPAP Auto SV marketing literature gives a feature rundown, compared side-by-side with the Resmed Adapt:


The above image was originally posted by SAG in this thread:
viewtopic.php?t=16527&highlight=asv+fixes

You can see this newly approved Respironics model has back up rate options as well as higher EPAP capability. Quite a few other bells and whistles too. Just don't know if it's your multi-issue PAP solution. Good luck! I'm way over due dropping you an email. Thanks again for the info, Frequen!

frequen, in all seriousness, I wonder if an S8 Elite CPAP machine, set at 12 with EPR at "2", might not give you very good treatment all night long. One machine on your nightstand. And it would be a nice small size for travel.

Also wonder if the doctor evaluated you for cyclic alternaing pattern, cardiorespiratory decoupling, vagal tone, etc. Any unique findings there?