Getting "over inflated"

[-SWS]

Lastly, beware that message boards can be a "dial wingers" paradise. In general people love to help. And in general some helpful people simply don't know what it is they don't know---strange as that entirely lacking type of self assessment sounds. Proceed with caution if the dial wingers decide to woo you.

Whatchu talkin' 'bout Willis?

When I read the part I bolded, I thought of this......

"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know." - Donald Rumsfeld

Yes, proceed with caution.....don't be a "dial winger" unless/until "you KNOW what is is you don't know"....

Den

I just knew that was going to elicit a response! I even got an implicitly reproachful PM. Interestingly both people who responded are two of the most sensible and cautious posters we have---well-educated posters who make very responsible suggestions IMO. I don't recall either of those posters ever suggesting settings for medically challenging cases on these message boards. Honestly, you two always seem to intuitively know when the ratio of known-factors to unknown-factors gets unwieldy.

By contrast there is never a shortage of people on message boards who are avidly willing to wager their best guesses when diseased physiology drastically and obviously deviates from simple obstructive apnea. Voila! Enter the avid guessers! Now why is it that you two posters never enter those threads with specific settings to try? Because you understand perfectly that there is plenty that you don't know.

Now for the PM assessment that my statement was inflationary (you know who you are ). I too understand that there is very little about physiology that I truly understand. I understand that my ignorance of fact far exceeds my knowledge. I also understand that being wrong is much like quantum mechanics: we can predict the aggregate rate but we can never predict the individual occurrences. When I wake up each morning I seldom revel in what very little in this world I truly know. Rather I set about the business of methodically addressing my remaining vast ignorances. I expect to be wrong and I expect to be ignorant---again and again. It's a "deflationary" given.

So is it ignorant or egotistical of me to wish that some members of this message board were a little more reluctant to dive in with guesses when cases are medically challenging---and to be a little more inclined to recommend professional assistance? Quite honestly, I don't think it is. I think it's a perfectly rational opinion. And it's an opinion that doesn't get voiced nearly enough on this message board. Message board help is clearly a knife with two edges. Ironic that the two people who took issue with my position have always wielded the correct edge of the knife---when I'm positive they have repeatedly noticed that same two-sided message-board knife employed with sorely lacking caution.

[Wulfman]

"A man's got to know his limitations." - Dirty Harry Callahan from "Magnum Force".

-SWS,

I was just havin' a little fun with ya.
There are definitely areas of this therapy that I will NOT offer an opinion.....at least on settings.....and those are (mainly) the discussions on Bi-Level therapy (and in particular, the more sophisticated machines). However, if I happen to have any documentation that I can pass on to the users, I'm always glad to do that for their own self-education and awareness.

Most of the time, I know my limitations.

Den

[-SWS]

Den, you never come even close to being reckless. You understand perfectly what it is that you understand perfectly. Unfortunately that trait is not universal.

My ignorances are a complete quagmire. That statement doesn't come from low self image. It comes from realization of vast outstanding or missing knowledge. By contrast there are plenty of our species who subscribe to this self-aggrandizing rhetoric: "Ignorances? What ignorances?"

I'm just barely smart enough to know how damn dumb I am... which is negligibly smarter than barely knowing enough to be dangerous.

[den942]

I think these are the current settings as they are written on my receipt for the machine:

IMO it's a good idea to learn how to at least check the actual settings in your machine against those prescribed values. Not to sound overly harsh, but as ozij correctly points out, we have seen very many machines set up incorrectly by clueless DME providers. Then again we also have some DME providers who post here that are nothing short of superb IMO. I'd personally take Wulfman up on his typically generous offer for the clinician manual if I were in your shoes.

Max IPAP +19
Min IPAP +12
EPAP + 9

These values are undoubtedly common and reasonable for many. Nothing out of the ordinary here IMO.

Rate= 10
IT 1.2

You'll see in the BiPAP AutoSV clinician manual that Backup Rate (yours is prescribed at 10) and Inspiratory Time (yours is prescribed at 1.2) generally work together to achieve not only breath rate, but also a ratio of inspiration to expiration (I/E). Respironics does not want time spent in inspiration to exceed time spent in expiration. Accordingly, as a clinician enters a value for Backup Rate, Inspiratory Time may automatically adjust downward in the process so that time spent in I does not exceed time in E. That automatic adjustment of IT during clinician setup will occur so that IT is set at exactly half the value determined by Backup rate.

So with that Backup Rate of 10 breaths per minute, Respironics will assume a time of 6 seconds per breath. If Respironics needed to automatically adjust Inspiratory Time in your case (and Respironics clearly does not), then that 50/50 ratio rule would make sure that IT is set at half of your 6 seconds. If IT were above 3 (and it is not) then the Respironics setup algorithm would set that IT value at exactly 3 to automatically achieve a 50/50 I/E ratio.

So your two values above kind of hint at your sleep lab quite possibly having wrestled a bit with your breath stacking problem. That Rate of 10 allows for each breath (I+E) to be as slow as 6 seconds. And that IT allows for each inspiratory phase (each breath in) to be no longer than 1.2 seconds in duration. Those settings clearly favor allowing you to spend significantly more time in the expiratory phase (breathing out) to cope with that breath stacking tendency. I doubt you can or should set that IT much lower. Ratio-wise IT is already set pretty low.


Those 10 and 1.2 settings kind of hint at your breath stacking problem in the lab IMO.

RT 3

That's a rise time of 0.3 seconds, by the way. Very reasonable IMO. But RT=3 also happens to be the default or "hard coded" value (the latter actually) when BiFlex is turned on. Algorithmically BiFlex tries to account for the dynamics of elastic recoil and other dynamic changes in respiratory resistance. Great feature for most people. However, algorithms are not infallible IMO. Some people are known to experience breath stacking simply by having the Flex feature turned on. If BiFlex is enabled, you might want to try experimentally turning it off to see if that helps with the breath stacking.

Lastly, beware that message boards can be a "dial wingers" paradise. In general people love to help. And in general some helpful people simply don't know what it is they don't know---strange as that entirely lacking type of self assessment sounds. Proceed with caution if the dial wingers decide to woo you.

I'm not much of a "knob twisting button pusher" unless I'm sure of the outcome. On things I'm familiar with I can
"dial wing" with the best of them. lol Like I said this "Breath Stacking" isn't a normal occurence so I'm not real
concerned about it. I will call the sleep clinic and talk to them about it. Maybe they will suggest some knob twists
and button pushes I can do...

Thanks...

[den942]

Lastly, beware that message boards can be a "dial wingers" paradise. In general people love to help. And in general some helpful people simply don't know what it is they don't know---strange as that entirely lacking type of self assessment sounds. Proceed with caution if the dial wingers decide to woo you.

Whatchu talkin' 'bout Willis?

When I read the part I bolded, I thought of this......

"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know." - Donald Rumsfeld

Yes, proceed with caution.....don't be a "dial winger" unless/until "you KNOW what is is you don't know"....

Den

As soon as I get to know what unknowns I don't know, I may be tempted to wing a dial or two. I don't really want to know
everything because a little mystery in life is always nice. lol

[Wulfman]

As soon as I get to know what unknowns I don't know, I may be tempted to wing a dial or two. I don't really want to know everything because a little mystery in life is always nice. lol

You married?
If so, that should just about take care of all of life's "little mysteries" that one can handle.


Den

[-SWS]

Shhhh! Best not to lament out loud... My mysterious wife is in the other room! She might overhear us typing!

[den942]

As soon as I get to know what unknowns I don't know, I may be tempted to wing a dial or two. I don't really want to know everything because a little mystery in life is always nice. lol

You married?
If so, that should just about take care of all of life's "little mysteries" that one can handle.


Den

I'm as single as one can get. Been living alone since my youngest daughter moved out in '93. Well, not completely alone. I
breed flying squirrels for pets and hand raise orphan wild life for a nature center. I have a back that, after four back surgeries,
takes a 1 1/2 page report after an MRI. So I'm not real active in sports. Hand feeding critters is something I can do while I'm ridin' the rocker anyway.

[den942]

Shhhh! Best not to lament out loud... My mysterious wife is in the other room! She might overhear us typing!

I guess one advantage with my critters is that they never complain. They don't care if I'm out late. They don't ask for
much but food and water. But a good woman is a lot more fun... lol

[Goofproof]

Either one can be dangerious when pervolked. Jim

[Snoredog]

Those 10 and 1.2 settings kind of hint at your breath stacking problem in the lab IMO.

I believe the 10 BPM and 1.2 IT are the back-up rate machine defaults. When you are experiencing periodic breathing and/or central apnea in spontaneous mode they have you switch to those default settings. It is also my understanding that once you know the BPM from the spontaneous mode you set the Backup BPM to that value -2, but you keep the IT at 1.2.

So if a person is getting breath stacking in spontaneous mode shouldn't the machine switch to back-up mode and apply those settings? The result should be a shorter Inspiration Time whenever they reverted to machine assisted mode.

On his Rise Time value=3?; I believe his Rise Time would only be valid in Manual mode? I didn't think it applied in Auto SV mode and it found that automatically.

[-SWS]

Those 10 and 1.2 settings kind of hint at your breath stacking problem in the lab IMO.

I believe the 10 BPM and 1.2 IT are the back-up rate machine defaults. When you are experiencing periodic breathing and/or central apnea in spontaneous mode they have you switch to those default settings.

Auto is the default setting. But when Auto is not turned on the manual defaults are 15 BPM and 2 IT. Also note those 15 BPM and 2 IT default settings yield that Respironics default or preferred I/E ratio of 50/50. When Auto is turned on, both the BPM and IT settings are automatically handled by that single auto parameter. The Auto (BPM & IT) setting is designed to take care of both periodic breathing and central apneas in almost all cases.

It is also my understanding that once you know the BPM from the spontaneous mode you set the Backup BPM to that value -2, but you keep the IT at 1.2.

That manual (BPM - 2) setting allows spontaneous breathing to be comfortably backed up, versus short-cycled or forced. However, I don't think the IT 1.2 is a default or universally-preferred manual setting. Could be wrong about that last part, though.

So if a person is getting breath stacking in spontaneous mode shouldn't the machine switch to back-up mode and apply those settings? The result should be a shorter Inspiration Time whenever they reverted to machine assisted mode.

Well, the machine will back up the following situation only: the leading edge of inspiration is missing or late. The backup feature itself isn't inherently advantageous for incomplete or short-cycled exhalations. Then, the IT setting causes the machine to cycle from I to E---again yielding no inherent advantage that copes with incomplete exhalation or "breath stacking". Then, to complicate matters, when breath stacking occurs, the Auto backup rate calculation is going to get skewed with erratic values toward an automatically maintained BPM. That's why it's advantageous to turn Auto BPM off in favor of an appropriately set manual value for severe cases of breath stacking.

On his Rise Time value=3?; I believe his Rise Time would only be valid in Manual mode? I didn't think it applied in Auto SV mode and it found that automatically.

Well, the Auto SV mode itself only maintains how high or low IPAP will automatically peak for each breath. Rise time can still be manually set for this machine's ASV modality. Then there was that other "auto" parameter we were just discussing in the above paragraphs. That auto parameter is turned off in favor of 10 BPM and 1.2 IT. Here rise time can be manually set and is apparently prescribed at 3 ( or 300 milliseconds).

So they removed the Auto backup setting that was default. Then they migrated away from the 15 BPM and 2 IT manual defaults and that 50/50 ratio, to allow Den942 plenty of extra ratio time to be spent in expiration----which is exactly what someone with a breath stacking problem needs: more opportunity to breath out.

[Snoredog]

That auto parameter is turned off in favor of 10 BPM and 1.2 IT. Here rise time can be manually set and is apparently prescribed at 3 ( or 300 milliseconds).

So they removed the Auto backup setting that was default. Then they migrated away from the 15 BPM and 2 IT manual defaults and that 50/50 ratio, to allow Den942 plenty of extra ratio time to be spent in expiration----which is exactly what someone with a breath stacking problem needs: more opportunity to breath out.

That seems right but that 10 BPM and 1.2 settings seemed familiar to something I've seen before, appears they come from the Respironics Protocol Titration guide for that machine in the decision tree, with obstructive taken care of, if Periodic Breathing/Central apnea is present it instructs you to set the machine to a "minimum" 10 BPM (or -2 below Spontaneous BPM rate) and IT 1.2 seconds.

So are they treating this "stacked breathing" the same as Periodic Breathing/Central?? That is what it appears they are doing by use of those backup settings.

I think I understand what the stacked breathing is, similar to taking 2-3 short breaths without any exhale. I guess those settings would work if his Spontaneous BPM was 18 that would surely get his attention and slow things down. The only point here is we don't know actually what his Spontaneous BPM is, if that was known the backup BPM should be that value -2 and not particularly 10 BPM which is the Minimum they recommend. But once you know what the Spontaneous BPM is you are supposed to set the backup BPM to that value -2.

I'm only saying this because if his backup BPM is set to 10 and he experiences Periodic Breathing and/or a Central the same thing can happen when he switches from User mode to Machine mode, he could go from 18 BPM to 10 BPM all of a sudden (e.g where maybe he should be at 16 BPM with the shorter IT time to eliminate the stacked breathing).

So if the person stays in Spontaneous mode 99% of the time it doesn't really matter what that backup mode is set at, BUT it could be a surprise awakening if left in the manual mode and set incorrectly. My understanding is the Auto mode for backup is only used long enough to set up Spontaneous mode, then backup is set to manual. This way if the machine switches it switches from a mode where breathing is not ideal to a known good pattern slightly uncomfortable but to slow things down.

I'm just trying to think this out is all and we know how well they set these things up,

[-SWS]

So are they treating this "stacked breathing" the same as Periodic Breathing/Central?? That is what it appears they are doing by use of those backup settings.

My best guess is that the clinicians were forced to compensate for a fairly challenging BiLevel side effect of "breath stacking"----as they also attempted to treat the primary SDB component.

But breath stacking, periodic breathing, and central apneas are three different and very unique problems in central physiology. And to complicate matters, attempting to treat one of those problems in biology can severely skew or even cause the others. For the most part, periodic breathing (which is a biologic problem of inspiratory overshoot/undershoot) is addressed with how high or low an ASV machine decides to deliver peak IPAP for each breath. And primary occurrences of central apneas (latent or missed inspiration) are compensated with that timed backup. My understanding is that "breath stacking" can be very challenging to compensate, but that clinicians frequently attempt to create a larger ratio or window of opportunity in which the patient might manage to properly and fully exhale before taking that next breath in. These are three very unique problems in central respiration with three very unique primary treatment approaches. When two or more of those problems show up in combination, the clinician literally has a juggling act on their hands.

But once you know what the Spontaneous BPM is you are supposed to set the backup BPM to that value -2.

Right. I think that offset of 2 you mention is a fairly standard protocol for manually setting backup rate. You don't want the machine to lead or prematurely trigger inspiration when the spontaneous respiratory drive is largely functional or intact. Rather, you want the spontaneous or biologic respiratory drive to "run the show" so to speak, with a nice unobtrusive backup rate in place that intentionally falls a bit short of that largely functional spontaneous respiratory drive. So that's the general reason for the timing offset of 2----so that biology is allowed to comfortably run the show for most breaths and not machine timing.

However, in the case of "breath stacking" clinicians may need to offset spontaneous BPM by more than 2 to compensate with that much better expiratory ratio or window of opportunity in which to breathe out. Tricky caveat: using an offset of more than 2 in an attempt to compensate for breath stacking may not be feasible in biology---if the timed backup needs of a latent/remiss central respiratory drive actually need to be much closer to spontaneous rate. It's theoretically possible to be painted in a corner regarding multiple pathology components and their respective or intended treatments. Here it's theoretically possible to address breath stacking with that altered I/E ratio, but at the expense of sacrificing a much needed and much "tighter" time window in which to back up primary central apneas. My understanding is that quite often juggling acts in complex pathology and combinatorial treatment can be adequately achieved. But sometimes outstanding components or symptoms are allowed to remain slightly under-treated simply because that's the best treatment combination that was possible. It's entirely possible that those infrequent breath stacking symptoms that Den942 mentioned represent not only the best possible treatment in his case, but a damn good titration from some incredibly skilled clinicians.

[den942]

However, in the case of "breath stacking" clinicians may need to offset spontaneous BPM by more than 2 to compensate with that much better expiratory ratio or window of opportunity in which to breathe out. Tricky caveat: using an offset of more than 2 in an attempt to compensate for breath stacking may not be feasible in biology---if the timed backup needs of a latent/remiss central respiratory drive actually need to be much closer to spontaneous rate. It's theoretically possible to be painted in a corner regarding multiple pathology components and their respective or intended treatments. Here it's theoretically possible to address breath stacking with that altered I/E ratio, but at the expense of sacrificing a much needed and much "tighter" time window in which to back up primary central apneas. My understanding is that quite often juggling acts in complex pathology and combinatorial treatment can be adequately achieved. But sometimes outstanding components or symptoms are allowed to remain slightly under-treated simply because that's the best treatment combination that was possible. It's entirely possible that those infrequent breath stacking symptoms that Den942 mentioned represent not only the best possible treatment in his case, but a damn good titration from some incredibly skilled clinicians.

Without getting too long winded or technical they told me Ikept them quite busy during my titration and that I was a complicated case with many things going on. They mentioned the two types of apnea and that at times I had both at
the same time. They said I also had some RLS problems. Somewhere around here I have a copy of the report sent to my
doctor. It was quite afew pages.

Geez, between my brain, back, and sleep problems, maybe I need to donate my body to a medical school while I'm still
using it. They could give me free room and board and have student doctors diagnoses my problems.. lol