No Answers Yet For Problems With ASV

[Paper_Nanny]

Deborah, the text in your PSG report is fuzzy (not in focus).

It was a bad photocopy, but here is the titration study in a more legible incarnation.

[Paper_Nanny]

Deborah, the text in your PSG report is fuzzy (not in focus).

And here is a more legible version of the original sleep study.

[avi123]

[quote="Paper_Nanny"][quote="Paper_Nanny"]


And here is a more legible version of the original sleep study.[/quote="avi123"]


I still don't understand it why they have not decided on a plain CPAP after the first PSG, when you had AHI of 5.7?

[BrianinTN]

I still don't understand it why they have not decided on a plain CPAP after the first PSG, when you had AHI of 5.7?

Paper_Nanny had a diagnostic AHI of 7.0, but only about 1.3 of that came from obstructive apneas. The rest was mostly central apneas and hypopneas (3.8 and 1.9, respectively). Also, even though an AHI of 7 doesn't seem that high, (1) it is above the generally accepted threshold of 5, therefore qualifying as "mild" apnea, and (2) note that she had a large cluster of events during her brief period of REM sleep (AHI of 15.7).

Because she experienced mixed apnea rather than simple obstructive apnea, that's probably why they skipped the CPAP. The decision of treatment modality isn't about the severity of AHI so much as it is about its constitution. Their attribution of her central apneas is attributed partially to the MS, which may have also tilted the balance in favor of a ventilator that sports a backup rate like an ASV. Does that help?

I took a very quick look at your report images, and it's tough to make out the numbers, but it looks like you had more central apneas than obstructive apneas in your diagnostic study. Is that right? And that your AHI during your ASV titration was actually slightly worse than in your diagnostic study (5.7 in the diagnostic and 7.6 in the titration) while your total RDI was about the same (7.2 and 7.6, respectively)? I know those numbers are over the course of the whole nights, and the report says in the text that the final settings "resolved all apneas," but it would be nice to know how things progressed. They only had you on the final settings for about an hour it looks like.

Remember me saying this two pages ago? Well, with your new images, we can see that a lot clearer now. This is actually pretty fascinating.

It looks like you had no respiratory events during your final 45 minutes of sleep with pressures of IPAP=15 and EPAP=8. However, once you got to an EPAP of 6, your events also became pretty darn rare (only 4 events over a few hours). All of those settings look very similar; it would be premature to conclude that the pressures of 15/8 were "optimal" because you had only a brief period of time at those settings. If you were to look at this statistically (nerd alert!) and look at the probability of a respiratory event over time, you would be forced to conclude that all of the settings above EPAP=6 are statistically similar given the available data.

As for why things seemed much worse at home than in the lab, it could be a number of things. You could have had a very good stretch of time in the lab. There could be differences in how events are being scored between the ASV and the lab (the latter being more reliable, but even a falsely-flagged hypopnea on your ASV could still be indicative of something not quite right). Also, while mentioning this makes me groan, the lab kept your pressure support at a minimum of 3, while your ASV at home isn't doing that right now -- so perhaps in your particular case the higher IPAP was useful in addressing some of your hypopneas. There is insufficient data to draw that conclusion at this point, however, and with your home data looking so good, I definitely would not tinker there any time soon.

I love your data! It makes some sense!

[avi123]

Looking at this guideline I don't see Paper_Nanny's numbers exceeding those allowed
to justify a BiPAP SV or an ASV machine. And if it does, it's only marginally so.

Especially, after the first PSG.

My question is if it's possible that Deborah was treated at the PSGs too aggressively and as a result was given complex machines unnecessarily?


Clinical Guidelines for the Manual Titration of Positive Airway Pressure in Patients
with Obstructive Sleep Apnea


Positive Airway Pressure Titration Task Force of the American Academy of Sleep Medicine, 2008


Summary: Positive airway pressure (PAP) devices are used to treat
patients with sleep related breathing disorders (SRBDs), including
obstructive sleep apnea (OSA). After a patient is diagnosed with
OSA, the current standard of practice involves performing attended
polysomnography (PSG), during which positive airway pressure is
adjusted throughout the recording period to determine the optimal
pressure for maintaining upper airway patency. Continuous positive
airway pressure (CPAP) and bilevel positive airway pressure (BPAP)
represent the two forms of PAP that are manually titrated during PSG
to determine the single fixed pressure of CPAP or the fixed inspiratory
and expiratory positive airway pressures (IPAP and EPAP, respectively)
of BPAP for subsequent nightly usage. A PAP Titration Task
Force of the American Academy of Sleep Medicine reviewed the available
literature. Based on this review, the Task Force developed these
recommendations for conducting CPAP and BPAP titrations. Major
recommendations are as follows: (1) All potential PAP titration candidates
should receive adequate PAP education, hands-on demonstration,
careful mask fitting, and acclimatization prior to titration. (2) CPAP
(IPAP and/or EPAP for patients on BPAP) should be increased until
the following obstructive respiratory events are eliminated (no specific
order) or the recommended maximum CPAP (IPAP for patients
on BPAP) is reached: apneas, hypopneas, respiratory effort-related
arousals (RERAs), and snoring. (3) The recommended minimum starting
CPAP should be 4 cm H2O for pediatric and adult patients, and
the recommended minimum starting IPAP and EPAP should be 8 cm
H2O and 4 cm H2O, respectively, for pediatric and adult patients on
Clinical Guidelines for the Manual Titration of Positive Airway Pressure in Patients
with Obstructive Sleep Apnea BPAP. (4) The recommended maximum CPAP should be 15 cm H2O
(or recommended maximum IPAP of 20 cm H2O if on BPAP) for patients
<12 years, and 20 cm H2O (or recommended maximum IPAP of
30 cm H2O if on BPAP) for patients ≥12 years. (5) The recommended
minimum IPAP-EPAP differential is 4 cm H2O and the recommended
maximum IPAP-EPAP differential is 10 cm H2O (6) CPAP (IPAP and/or
EPAP for patients on BPAP depending on the type of event) should be
increased by at least 1 cm H2O with an interval no shorter than 5 min,
with the goal of eliminating obstructive respiratory events. (7) CPAP
(IPAP and EPAP for patients on BPAP) should be increased from any
CPAP (or IPAP) level if at least 1 obstructive apnea is observed for
patients <12 years, or if at least 2 obstructive apneas are observed for
patients ≥12 years. (8) CPAP (IPAP for patients on BPAP) should be
increased from any CPAP (or IPAP) level if at least 1 hypopnea is observed
for patients <12 years, or if at least 3 hypopneas are observed
for patients ≥12 years. (9) CPAP (IPAP for patients on BPAP) should
be increased from any CPAP (or IPAP) level if at least 3 RERAs are
observed for patients <12 years, or if at least 5 RERAs are observed
for patients ≥12 years. (10) CPAP (IPAP for patients on BPAP) may
be increased from any CPAP (or IPAP) level if at least 1 min of loud or
unambiguous snoring is observed for patients <12 years, or if at least
3 min of loud or unambiguous snoring are observed for patients ≥12
years. (11) The titration algorithm for split-night CPAP or BPAP titration
studies should be identical to that of full-night CPAP or BPAP titration
studies, respectively. (12) If the patient is uncomfortable or intolerant
of high pressures on CPAP, the patient may be tried on BPAP. If there
are continued obstructive respiratory events at 15 cm H2O of CPAP
during the titration study, the patient may be switched to BPAP. (13)


The pressure of CPAP or BPAP selected for patient use following the
titration study should reflect control of the patient’s obstructive respiration
by a low (preferably <5 per hour) respiratory disturbance index
(RDI) at the selected pressure, a minimum sea level SpO2 above 90%
at the pressure, and with a leak within acceptable parameters at the
pressure. (14) An optimal titration reduces RDI <5 for at least a 15-
min duration and should include supine REM sleep at the selected
pressure that is not continually interrupted by spontaneous arousals
or awakenings. (15) A good titration reduces RDI ≤10 or by 50% if the
baseline RDI <15 and should include supine REM sleep that is not
continually interrupted by spontaneous arousals or awakenings at the
selected pressure. (16) An adequate titration does not reduce the RDI
≤10 but reduces the RDI by 75% from baseline (especially in severe
OSA patients), or one in which the titration grading criteria for optimal
or good are met with the exception that supine REM sleep did not occur
at the selected pressure. (17) An unacceptable titration is one that
does not meet any one of the above grades. (18) A repeat PAP titration
study should be considered if the initial titration does not achieve a
grade of optimal or good and, if it is a split-night PSG study, it fails to
meet AASM criteria (i.e., titration duration should be >3 hr).


Also:


4.4.6 Adaptive Servoventilation

4.4.6.1 Adaptive servoventilation may be considered if the patient
is observed to have Cheyne-Stokes respiration or if treatment emergent
central sleep apnea (i.e., complex sleep apnea) during
the titration study is not eliminated by down titration of pressure.

But no periodic breathing and/or Cheyne-Stokes were mentioned in the PSG.

As to emergent centrals if its so, it's not mentioned in the PSG report.

[BrianinTN]

Her doctor made the decision to have ASV titration as an option. The PSG technician doesn't just decide to do that on his/her own. For that reason, the MS very well could have played a role in the decision.

The doctor also has discretion in deciding what is "medically necessary". Insurance typically will not cover treatments for patients with an AHI too low, and I don't imagine most doctors would recommend something in that case either (someone correct me if I am off base there). Why did they move to an ASV? As it says in the footer of the report: "Mild obstructive sleep apnea with central sleep apnea titrated with BIPAP, however still having central events. Patient was then titrated with BIPAP SV which resolved all apneas..."

Paper_Nanny had an AHI over 5, and an AHI over 15 in REM sleep. That was good enough for her doctor to deem this treatment approach to be medically necessary and, more importantly, good enough for her insurance (I'm assuming based on the posts about the DME interaction). Despite her apnea being in the "mild" range, I think she is lucky to receive the most flexible and gold standard option, even if the split wasn't absolutely necessary.
(Edits: Previous final paragraph was too negative on the possibility of standard CPAP/BiPAP addressing centrals, as this seems to be a matter of some debate. Also added quotation from report footer.)

[avi123]

Brian, please let her answer. You "think" and "assume" endlessly!

[Paper_Nanny]

Also, while mentioning this makes me groan, the lab kept your pressure support at a minimum of 3, while your ASV at home isn't doing that right now -- so perhaps in your particular case the higher IPAP was useful in addressing some of your hypopneas. There is insufficient data to draw that conclusion at this point, however, and with your home data looking so good, I definitely would not tinker there any time soon.

Home data hasn't been looking as good the past couple nights. AHI on Wednesday night was 4 and last night, it was up to 5. Maybe some tinkering is in order here. What shall I try? Raising my IPAP min? Oh, wait, in reviewing my original settings, I see that raising the IPAP min will be impossible, so I'll skip that one. Maybe raise my pressure support min? That one I could do. Why do I feel like I am calling numbers for Bingo or drawing lottery tickets?

Lots of graphs at the end of the post. I think I got the illegibility problem taken care of and they should be okay to read.

I love your data! It makes some sense!

Wow, it's been a long time since a guy has said that to me! <looking in vain for the "batting my eye lashes" smiley!.

Tuesday 06-14 AHI= 2



Wednesday 06-15 AHI= 4



Thursday 06-16 AHI=5

[BrianinTN]

Home data hasn't been looking as good the past couple nights. AHI on Wednesday night was 4 and last night, it was up to 5. Maybe some tinkering is in order here. What shall I try?

Well, the conservative advice would be to give things time to stabilize. JohnBFisher, Slinky, and I are talking about the data collection aspect right now over in my periodic breathing thread.

Getting AHI under 5 appears to be the threshold for which most everyone aims. (Not to digress, but I'm actually curious whether that's because it's a Medicare and/or insurance threshold, or whether there have been studies demonstrating that's a turning point for many patients in terms of how they feel.) However, I've read stories on here of people who felt like garbage with an AHI of 4-5 and who felt great when it was closer to 0. In any case, it's really good that your AHI consists not of apneas but rather entirely of hypopneas, which are less detrimental.

The most important question is: putting aside the numbers (since they're all objectively pretty good), how do you feel?

OK, let me put on my data analyst hat. On your "best" night, the ASV changed your pressures virtually none at all. Your average PS was 1.0. Averages can be deceptive, but in this case, your night was pretty consistent. Now take a look at your "worst" night. If you line up where the hypopneas are occurring, it appears to the naked eye like you were having them both at low IPAPs and higher IPAPs. In addition, your leak was much worse on that night. Most interesting to me, I also notice that your PTB got progressively worse night over night, right along with the gradual increase in your HI. What does that all mean? I don't know. It could even be a spurious correlation. What does that mean you should do? I don't know. But...

Raising my IPAP min? Oh, wait, in reviewing my original settings, I see that raising the IPAP min will be impossible, so I'll skip that one. Maybe raise my pressure support min? That one I could do.

It's a little confusing, but on our ASVs, when you raise your min PS, you actually are raising min IPAP. On our ASVs, min IPAP is just a variable rather than a constant number. Expressed as an equation, Min IPAP = min EPAP + min PS. Will raising min PS (and therefore in effect min IPAP) help? Seems like it might have made your first night worse, but maybe there would have been no effect. A higher IPAP might address the hypopneas you experienced in your second and third nights -- or it might not. Increasing min PS also could have a negative iatrogenic (i.e., treatment-induced) effect. We don't know for sure. Have I raised more questions than I've answered? Good.

Why do I feel like I am calling numbers for Bingo or drawing lottery tickets?

Honestly, I think this is the strongest argument for playing it conservatively. I know some people treat machine tinkering exactly like that. Heck, I was impatiently doing the same thing myself a few weeks ago. But here's the problem. You have AHIs of 2, 4, and 5 the last three nights. Which one of those is closest to the "true" AHI at your current settings? We don't know. What if you hypothetically increase min PS and then, over three nights, get AHIs of 3, 3, and 4 -- what then? This is why I'd personally lean toward being conservative, trying to establish a baseline with a good amount of data at certain settings, and most important, let how you feel guide you.

All I ask is whatever you decide to do, let us know and keep sharing!

[avi123]

Lots of graphs at the end of the post. I think I got the illegibility problem taken care of and they should be okay to read.

Checking the literature for a target AHI for those on ASVs with CSA I see this:

◦Studies show that ASV is superior to conventional positive airway pressure therapy for controlling the number of central sleep apneas,[27, 28] improving sleep architecture and daytime hypersomnolence, particularly for CSB-CSA, central sleep apnea syndrome, and complex sleep apnea. In one study,[27] both ASV and CPAP decreased the AHI, but, noticeably, only ASV completely corrected CSB-CSA, with AHI below 10/h."

[Paper_Nanny]

Checking the literature for a target AHI for those on ASVs with CSA I see this:

◦Studies show that ASV is superior to conventional positive airway pressure therapy for controlling the number of central sleep apneas,[27, 28] improving sleep architecture and daytime hypersomnolence, particularly for CSB-CSA, central sleep apnea syndrome, and complex sleep apnea. In one study,[27] both ASV and CPAP decreased the AHI, but, noticeably, only ASV completely corrected CSB-CSA, with AHI below 10/h."

It difficult to assess the relevance of that information without the full context from which it was taken.

No, I was definitely not given a complex machine unnecessarily. I am not easily amused; I should always be given the most complex machine possible.

Seriously, though, I had central apneas showing up in the original sleep study. No, the numbers on average were not overly impressive, but, when considering that many of the centrals were during REM sleep and that I had very little REM sleep, it would follow that if the quality of my sleep improved such that I was having more time in REM, then the number of central events would increase. With all that in mind, I don't follow how you're wondering if the BiPAP SV or ASV is moe complex than what was needed.

The other reason I am having trouble following is that as far as I can tell, the tech in the sleep lab followed protocol and made the changes necessary to get my numbers where they needed to be. It didn't seem like she was skipping steps in the titration to get me the fancy machine. And, even if the tech had messed up, the information was reviewed by the RT and the MD. Having three trained professionals reviewing the information cuts down on the chance that a big mistake was made. (In theory, anyway...) And, if those three did miss the mistake, there was one more chance to catch the incorrect assignment of machine when the rental was reviewed by the one of the Professional Claims Adjusters at the insurance company. I don't know for sure that they reviewed it, but it would strike me as peculiar that they review most everything else and would fail to review the request for a more expensive machine than what is usually used to treat sleep apnea.

But, the bottom line is the same as my top line of this post. I should always be given the most complex machine possible. It is one of the Lesser Known Universal Truths. And now that I have a complex machine, I will fight like to protect "my baby" from being taken away, the same as any other wild animal mother would fight. Ferociously, with fur raised, teeth bared, and claws out.

Deborah

edit to remove a stray { from the post.

[Paper_Nanny]

Looking at this guideline I don't see Paper_Nanny's numbers exceeding those allowed
to justify a BiPAP SV or an ASV machine

My question is if it's possible that Deborah was treated at the PSGs too aggressively and as a result was given complex machines unnecessarily?

Brian, please let her answer. You "think" and "assume" endlessly

If Brian answered a question that was directed specifically to me and was a question only I could be reasonably expected to answer, I think it would be okay to take issue with him answering. But, avi123, your questions were not directed specifically to me. You refer to me in third person, which implies, "I am talking about Deborah, not to her." And, your questions were not ones that I only I could be reasonably expected to answer. For example, if you had asked, "How is Paper_Nanny feeling today?" it would be silly for anyone else to answer, even though it was asked about me, rather than to me.

As for you saying that Brian is thinking and assuming endlessly, I understand how you could come to that conclusion. Brian's answers are very in depth and do show that a lot of thought and a few (usually logical) assumptions go into them. And I appreciate that. The answers he gave to your questions, for example, were much more thorough and cogent than anything I could have come up with. And while it is tempting to raise Brian to the level of Beings Who Think and Assume Endlessly, it is not right and proper to do so. Because, you see, even Brian ceases to think and assume at times. Sad, I know, and also true.

Deborah

[avi123]

Deborah, if you don't feel HORRIBLE any more as you stated in the heading of this thread then this should count
the most and we don't need to waste time about who said what to whom and when and how.

As I understand it, central apnea syndrome is usually caused by medical underlying conditions and the XPAPs are not meant to cure these diseases. XPAPs only deal with the sleep disorders aspects.

Some of the underlying medical conditions are these:

•The patient has a history of an underlying disorder other than heart failure or renal failure. Patients with stroke can have either classic CSB-CSA or central apneas without a crescendo-decrescendo pattern.
◦Stroke
◦Diabetes mellitus
◦Hypothyroidism
◦Parkinson disease
◦Multiple system atrophy or Shy-Dragger syndrome
◦Familial dysautonomia
◦Postpolio syndrome
◦Damage to medullary respiratory centers by tumor, infarction, or infection
◦Arnold-Chiari malformation types I-III
◦Cervical cordotomy
◦Muscular dystrophy
◦Myasthenia gravis
◦Prader-Willi syndrome
◦Idiopathic cardiomyopathy
◦Acromegaly

ETC.


There seems to be a problem on this board that a few posters who are using such ASV machines are exchanging set-up information as though everyone is suffering from the same underlying condition. As I understand it, this is not the properway if you check the following:


How does one set the servo ventilator? The EPAP is
set to a level that can treat obstructive apneas and obstructive
hypopneas and before central hypopneas manifest,
but there may be some inter-observer variability in determination
of such a pressure level . Some investigators believe that the EPAP level should not exceed 15 cm
H2O in patients with heart failure and central apneas, due
to concerns surrounding decreased venous return and consequent
hypotension in a preload-sensitive cardiac condition.

But, as I mentioned above if you're satisfied with your present achievements and condition then good luck on it!

[Mr Bill]

avi123
Its true, those of us that have these ASV's, to all appearances, are swapping recipes like a bunch of mother hens. We all need to step back and not get angry at each other. This is very scary at first. I think helping with unfamiliarity and frustrations and/or with fears is a lot of what this forum is about. I read a lot of people helping out each other with CPAP and BIPAP and I read them with great interest. I especially read the ASV stuff with interest because I want to know what other people are experiencing. I can directly relate because I have one. I sort of wonder if you would be posting some of these questions relating to whether patients should get an ASV, if you had an ASV yourself.

My experience with CPAP and BIPAP was only one night in the sleep lab. I'm sure it was at least partly a negative experience because, CSA aside, it was my first time experiencing wearing a mask and having to trust a box to deliver air to me. It played heck with all my asthma fears let me tell you. But my CSA got worse with pressure for both CPAP and BIPAP and worse with oxygen. So, it is ASV for me.

I've appreciated all the posts between other board members that help each other be more comfortable and get actual good sleep. Its pretty clear that with the low incidence of CSA patients (maybe 1:500) many doctors may never have had a CSA patient. Maybe also many DME's, being bureaucratic, may not have a person at the point of treatment, who knows anything about ASV's. One thing I learned right off is this ASV won't kill me if I have it adjusted wide open. I may not sleep but I won't die. I was very fearful at first, wearing a mask and trusting this box. The darned thing worked when nothing else could. My first night it breathed for me for 25% of the night. However, when I found I was conflicting and having trouble sleeping I had no problem going right over to my RT and working it out over several nights. My take on this is, if you are not at deaths door, e.g. your life does not hang in the immediate balance, you can fiddle these machines a bit for comfort and better sleep. Along the way I think we all hope to learn what is happening, in ourselves how we feel about it, in our treatment how it is affecting our condition, and just what our condition and path are going towards as an outcome.

So the doctor thought the ASV doing all the work initiating breathing was preferable and the Respironics rep said its not preferable but its not unsafe. The latter, being the obvious better answer. This just shows how unfamiliar these units are to some physicians. I work as a chemist and I am a huge instrument / data / PC nerd from all the way back. I am good at understanding machines either from their specs or by intuition and getting them to work. I don't expect my doctor to necessarily understand how one works unless he wanted to strap one on and thoughtfully try it for a few weeks.

Lets see what may have caused me to have CSA?

(0) I've never experimented with any reality altering drug except alcohol. I'm a moderate drinker. My only exposure to opioids were for two knee surgeries. The last one was in 2000 and I recall as I was coming out of anesthesia, complaining over and over that I could not breath (could not feel that feeling that breathing was giving me oxygen) and being assured over and over that my blood oxygen was fine. The doctor said he left enough anesthesia and morphine in my knee to last for 2-3 days. CSA feels like that.

(1) GERD, probably for 25 years, since back when I weighed only 165 started back around 1980. I never knew what the problem was, it was just this persistent cough when I was tired and acid reflux but no doctor made me aware that sinus drainage and asthma like symptoms went hand in hand with GERD.

(2) Hypothyroidism, Hashimoto's thyroiditis got me in 1989

(3) Asthma, mild but made worse by GERD, asthma diagnosed in 1994
Summer of 2006 complained of vertigo and odd perspective shifts. We did whole battery of eye, throat, sinus, neurologist; no findings.
Asthma symptoms greatly decreased by sleeping supline and elevating head of bed 6 inches, Spring of 2008 when thank God, I realized I had GERD and acted on my own. Dr then concurred with diagnosis.

(4) Started reporting sleeping problems fall of 2008. Was dead on feet reported whole body numbness. I got conduction tested for MS, with negative results. Sudden gain of 30 pounds. Neurologist suggested I exercise more.

(5) Fall of 2008 Blood pressure began rising rapidly and resisted treatment
Sleepnessness attributed to new cat and possible alergies. Spent much of 2009 in a mental fog but was not really aware it was a sleep problem.

(6) My mother was diagnosed with CSA in 2009, but I was unaware of the diagnosis, or its hereditary significance.
My CSA came on like gangbusters late summer of 2010, I woke up over and over, knowing I was simply not breathing. I was scared to fall asleep. I bought a pulse oximiter and proved to my doctor that I had sleep apnea. Two polysomnography studies later, here I am.

(7) Joint pain in hands and feet along with numbness, slightly elevated uric acid since CSA started.
Elevated triglycerides and uric acid, went along with the blood pressure rise. I did the sugar tolerance test and passed. So far, uric acid is barely at top of normal range, no gout, YAY!

So many of these things are getting better because I am finally getting sleep.
My blood pressure is down, my GERD is healing, I am loosing weight, the numbness goes away when I have slept well, and my arthritis/gout in hands and feet pain is greatly lessened. It seems to me that sleep apnea causes a whole raft of inflammation and/or excessive immune response conditions.

Maybe its all because I'm left handed.

Edit: I should add that I had done the ECG and treadmill test in 2006 and passed with flying colors. In the fall of 2007 my little brother died of myocardial infarction. He had lost 65 pounds over 6 months with weight watchers. We now think he may have also had sleep apnea. I don't know if it was also CSA. I got a calcium CT scan done in the fall of 2007 and got a score of 1. So, no calcium related blockages. So, apparently my CSA is not heart related in the blockage sense.

[JohnBFisher]

MrBill, well said. Paper_Nanny, I definitely agree that if the protocols were properly followed and the ASV was prescribed accordingly (as is true in your situation), an ASV unit seems to be the best choice for you. The low percentage of patient initiated breathing would seem confirm that.

avi123, you are correct that there is often (but not always) an underlying health condition that causes CSA. Sometimes it just happens. It might be hereditary (as it seems to be for MrBill). It might just be some weird problem for an individual. Then it is known as Ideopathic CSA. The point is that if CSA exists, it may be that only by using an ASV unit can the CSA be treated. Often the underlying condition resists any form of therapy. In my case, I have a neuro-degenerative disorder (Sporadic OPCA and possible MSA). It impacts the brain stem and cerebellum. The brain stem controls breathing. Even during the day I find my breathing is rather erratic. And an arterial blood gas test shows the same thing. Now, I sure wish something could help address the source of my problem. But NOTHING can be done. So, we treat the symptoms to minimize their impact.

I also agree that sometimes people are too willing to fiddle with all the dials. It is why I recommend that the changes be made in conjunction with a doctor. The doctor should be aware of the problem and what the patient is attempting to correct. Then if improvement happens, the doctor should be apprised of what had to be done to improve the situation. That becomes part of the medical record. It helps the doctor better understand the situation for the patient. But that's exactly what I see MrBill and Paper_Nanny doing. They don't make changes without a plan of attack. And without involving their doctors.