CPAPtalk.com

Wow!

Like with a log-jam, when the key log gets removed, a massive flow results. Ooh, ooh ... an even better analogy would be flow limitations and obstructions ... (Okay, I'm done with reflection, now.)

Ozij, I'm not sure I understand what information about the PB420E you were asking for, but mine is set for 6-12 cm (pretty wide I know, but I find that preferable to aerophagia), FL1 (I think, but whatever the non-default setting is).

One point needs to be stated regarding complete blockage and the measurement of that blockage. As the blockage begins to severely restrict flow through the windpipe, the difference in pressures above and below the obstruction build quickly tending to force total occlusion.

Couple that with accuracy limitations of measurement, and 20% begins to look like a good point at which to declare apnea. For practical purposes it seems reasonable that almost all obstructive events leading to such a low level of flow would quickly lead to total occlusion due to the large build-up in pressure differential.

My point is that the occlusion slams shut quickly, sealing with saliva, and the blockage is complete.

Doesn't provide much useful info about central events though.

If the machine calls it apnea, then in almost all cases it's likely to reflect complete occlusion (except, of course, for when it's central apnea).

Regards,
Bill

ozij wrote:

Wulfman wrote:xyz,

You only see those events (NR & FL and a few different charts/reports) from a machine that's capable of being set to Auto mode and when it IS set to Auto mode.

Den

On the PB you can set up minimum=maximum in auto mode and then get all the details you get in auto mode. Is that possible in Respironics? Resmed? I don't see why it shouldn't be possible - but would like to have it confirmed.

Thanks.
O.

Yes, you can do that with Respironics (as Den described) and with resmed autopaps...using them in "auto" mode with max/min set to the same number in order to see the additional detailed data (flow limitations, for example) that wouldn't be recorded in just "cpap" mode.

Thanks, RG.

Bill (and others...),
I always wondered at what looked like PB's idiotic "initial pressure" parameter, which could only be set to equal the min, or go above it. Absurd, in a machine that has ramp in auto mode.

I was reading Rapoport's paper on Caridac Oscillations, and Rapoports patents, and I think I've finally discovered why the "initial pressure" is there, and it's by no means idiocy, on the contrary -it's brilliant.

If you read US Patent no. 5803066, (also no. 5,546,933) given to Rapoport et. al. and later sold to PB, you will see that the PB auto algorithm assumes the existence of a prescribed pressure, a "preferred" pressure which is neither the min. nor the max. of the range. I'm adding emphasis to the quote, from pat. 5803066:

38. A breathing device for optimizing the positive airway pressure to a patient, comprising:

a source of breathing gas at controlled positive pressure to the airway of a patient;

a flow sensor configured to generate first data values representative of an inspiratory flow of breathing gas to the patient;

computer memory configured to store the first data values generated by said flow sensor;

a microprocessor including means for calculating the area of the inspiratory waveform from said first data values and calculating the area of a pure sine wave to generate a ratio of said areas and configured to generate a first signal when said ratio indicates a flow limitation in the patient; and

a pressure controller responsive to the first signal from said microprocessor and coupled to said source of breathing gas for increasing the positive pressure to the airway of the patient.

39. The breathing device of claim 38 wherein said micropressor is further configured to cause said pressure controller to increase the positive airway pressure to the patient at a greater rate when said positive airway pressure is less than a preselected prescribed pressure that (sic) when said positive airway pressure is greater than said preselected pressure.
40. The breathing device of claim 38, wherein said microprocessor is further configured to cause said pressure controller to decrease the positive pressure to the airway of the patient when said ratio does not indicate a flow limitation in the patient.

41. The breathing device of claim 40, wherein said microprocessor is further configured to cause said pressure controller to decrease positive airway pressure to the patient at a greater rate when said positive airway pressure is greater than a preselected prescribed pressure than when said positive airway pressure is less than said preselected pressure.

The preselected prescribed pressure is the 420E's initial pressure. When you don't set an initial pressure, initial and min. default to same. Meaning that you are set up for a slow rise (inhibiting the machines preemptive capabilities) and speedy decrease back to your minimum - with not much chance of stabilizing around a preferred pressure, since the machine assumes preferred=min.

If you set up an initial pressure, closer to your preferred or prescribed, the machine will climb up to that quickly - being very responisve to flow limitations, snores etc. and then add further pressure more carefully, Once higher than your preferred pressure, it will drop back to that quickly and then drop further more carefully.

The bottom line is that you have more chances of staying at or below an optimal pressure if you tell the machine what it is.

This is a very different logic from the Respironics algorithm.

The difference in rate of change is true for all breathing events. Not setting up the initial pressure therefore hobbles the PB's ability to respond quickly to apnea precursors.

Now, the machine does start therapy mode out at initial pressure. Which is why ramp is crucial (no optional) in this automatic machine. If your initial pressure is too high for comfort, you use the ramp to fall asleep. The machine check your breathing at optimal pressure, and will gladly drop you down if everything is OK.

The following must be read with caution, since the change for me could have been caused by less humidity - and I'm too happy to do more testing right now:

My recommended (90%) is almost always 7. By defining my min. at 6 and my max. at 8, the machine does an excellent preemtive job, and my apneas rarely bring about a pressure response above 7. My AHI is the best ever, and I have less of PB mixed apneas - whatever they are.

All in all, I think you may have a better chance of less pressure and less aerophagia if you define an initial pressure above 6.
O.

ozij wrote:I always wondered at what looked like PB's idiotic "initial pressure" parameter, which could only be set to equal the min, or go above it. Absurd, in a machine that has ramp in auto mode.

I was reading Rapoport's paper on Caridac Oscillations, and Rapoports patents, and I think I've finally discovered why the "initial pressure" is there, and it's by no means idiocy, on the contrary -it's brilliant.

---snipped---

If you set up an initial pressure, closer to your preferred or prescribed, the machine will climb up to that quickly - being very responisve to flow limitations, snores etc. and then add further pressure more carefully, Once higher than your preferred pressure, it will drop back to that quickly and then drop further more carefully.

The bottom line is that you have more chances of staying at or below an optimal pressure if you tell the machine what it is.

This is a very different logic from the Respironics algorithm.

The difference in rate of change is true for all breathing events. Not setting up the initial pressure therefore hobbles the PB's ability to respond quickly to apnea precursors.

Now, the machine does start therapy mode out at initial pressure. Which is why ramp is crucial (no optional) in this automatic machine. If your initial pressure is too high for comfort, you use the ramp to fall asleep. The machine check your breathing at optimal pressure, and will gladly drop you down if everything is OK.

---snipped---

All in all, I think you may have a better chance of less pressure and less aerophagia if you define an initial pressure above 6.
O.

ozij! What a find! And what a wonderful analysis, ozij!

Excellent information about the 420E. Like you, I had wondered why did they bother to put in a "start pressure" setting. Figured that was if a person wanted to start higher than the minimum that had been set in the range, but didn't know "why" that would be useful.

Since I set a much wider range at the top with my 420E than you do, I'm going to drop my min down some from the 8, 9, or 10 I usually use as the minimum, and try various higher "start" pressures with mine, giving each about 5 days to get a good look.

Most interesting info you dug up, ozij! Thanks!

NightHawkeye wrote:mine is set for 6-12 cm (pretty wide I know, but I find that preferable to aerophagia), FL1 (I think, but whatever the non-default setting is).

Bill, if you are seeing FL1 in the LCD on the PB 420E autopap, that setting (for IFL1) is still set for the factory default of "on". If you turned off the IFL1 setting in "Advanced Settings" (via the Silverlining software) it would show in the LCD as FL0 (zero for "off".)

Confusing, I know, since there are two different "FL" settings -- IFL1 and IFL2. Both come from the factory set to "on." But only one of them (the IFL1 trigger) actually shows up in the LCD -- and it shows up in the window as just "FL", accompanied by a 1 (for "on") or a 0 (zero for off.) The IFL2 trigger setting doesn't show up in the window at all.

FL1 in the window means the trigger called IFL1 is still turned on.

If the machine has not been running the pressure up unusually high and often for you, having IFL1 on ("FL1" in the LCD) is probably fine for you. I had to turn IFL1 off (FL0 <zero> in the LCD) on my machine. I think ozij did, too. Having IFL1 on (FL1 <one for "on"> in the LCD) apparently works for most people, though, or it would not come from the factory with the default of on.

Thanks for volunteering Rested Gal... I knew I'd pique your curiousity.... I'm almost tempted to join... I'm almost tempted to joins, since it was only while writing that I realized how the preemption was hobbled by not having an initial pressure.

O.

ozij wrote:........
If you set up an initial pressure, closer to your preferred or prescribed, the machine will climb up to that quickly - being very responisve to flow limitations, snores etc. and then add further pressure more carefully, Once higher than your preferred pressure, it will drop back to that quickly and then drop further more carefully.

The bottom line is that you have more chances of staying at or below an optimal pressure if you tell the machine what it is.

This is a very different logic from the Respironics algorithm.

Thanks for explaining this to us. That could be a significant advantage over the Respironics machine I chose. Since I eventually gave up use of the C-Flex and A-Flex settings, I think I am missing three nice advantages of the 420E:

-The "initial pressure" algorithm.
-Reading and appropriately responding to cardiac oscillations.
-Maybe a better software than Respironics?

Thanks Ozij!

Superb discovery and text emphasis by ozij regarding the 420e!

I don't currently have Silver Lining installed on any of my computers. I wonder if anyone wouldn't mind taking a peek at SL3 to tell us what the online guide says (if anything at all) about "initial pressure". More importantly I'm wondering just what the 420e set up guide clearly (or vaguely) tells clinicians to do regarding "initial pressure".

The great discussion continues!

Ozij,

A true detective I greatly appreciate your discoveries as it has helped me to understand just how different the Auto algorithms are between vendors. I had previously though there wasn't that much between them.

Each machine seems to have its own special features. I regard my older PB330 as a work of art that set the pattern for future miniaturization of blowers for all vendors.

Have ever tried the Pb4xx Auto just the PB420S & that was an amazing example of further miniaturization. The blower in it is so unbelievably small for the CMS it can deliver.

DSM

rested gal wrote:

ozij wrote:

Wulfman wrote:xyz,

You only see those events (NR & FL and a few different charts/reports) from a machine that's capable of being set to Auto mode and when it IS set to Auto mode.

Den

On the PB you can set up minimum=maximum in auto mode and then get all the details you get in auto mode. Is that possible in Respironics? Resmed? I don't see why it shouldn't be possible - but would like to have it confirmed.

Thanks.
O.

Yes, you can do that with Respironics (as Den described) and with resmed autopaps...using them in "auto" mode with max/min set to the same number in order to see the additional detailed data (flow limitations, for example) that wouldn't be recorded in just "cpap" mode.

RG,

I never realized this & never thought to try it

I have a Reslink on my S8 Vantage & it adds extra data over the std reporting from the machine without it.

I plan to add an SpO2 probe if they will only bring the price down for them. Slinky & I purchased several nonin devices that are identical to the required one but it turns out the ones we bought deliver a higher rate of data than the SpO2 unit used with the Reslink plus they have a different plug and one extra wire in the cable. Seeing we got them for approx $US30 each we figured it was worth trying them.

So, setting min & max to titration allows the machine to start at that CMS then vary CMS down and up as it sees fit (per algorithm) ? - great find.

DSM

dsm wrote:So, setting min & max to titration allows the machine to start at that CMS then vary CMS down and up as it sees fit (per algorithm) ? - great find.

DSM

I may be misunderstanding what you are saying there.

When you put an autopap in auto mode, but you set the minimum and maximum pressure to the same number (like "min 8, max 8") the machine will blow just 8 cm H20. Not varying. Blowing 8 as if it were in cpap mode at 8.

But since the operating mode is set for auto mode rather than for cpap mode, the machine will record the usual "autopap" data...including flow limitations data (which cpap mode doesn't look at.)

But in regard to treatment... the autopap set for auto mode at 8 min, 8 max will blow just 8 while it records events. It won't vary the pressure, 'cause it can't. You've leashed it to go no lower than 8 and no higher than 8.

Bill, I offer a couple thoughts relative to some of your recent points:

NightHawkeye wrote: One point needs to be stated regarding complete blockage and the measurement of that blockage. As the blockage begins to severely restrict flow through the windpipe, the difference in pressures above and below the obstruction build quickly tending to force total occlusion.

Here we are speaking of passive characteristics contributing to the dynamics of airway collapse. Some researchers are also trying to understand what role neural input plays in addition to these passive airway characteristics (regarding airway patency or collapsibility).

My understanding is that the Starling Resister model is deemed by many researchers in the field to be the best physics model to describe those types of passive airway dynamics that you just mentioned above.

However, a surprising finding (correct or incorrect) seems to be that the extreme vacuum pressures are more the survival response after the occlusion rather than the cause of the occlusion:

Kirkness, Krishnan, Patel, Schneider wrote: Rather, the markedly negative intraluminal pressures
generated by the diaphragm during periods of upper
airway obstruction were the consequence rather than the
cause of upper airway occlusion.

Whether we believe the above statement or not, that document makes for an interesting read describing passive (non-neural) factors contributing to both snoring and airway collapse (Adobe PDF document below):
http://content.karger.com/ProdukteDB/Ka ... nea_02.pdf

NightHawkey wrote: Couple that with accuracy limitations of measurement, and 20% begins to look like a good point at which to declare apnea.

I also suspect that 20% apnea definition-and-measurement demarcation was likely driven by the sampling rate, nonlinearity, and other measurement inefficiencies related to thermistor technology (presumably in predominant use when the apnea definition was first derived).

However, the inexpensive pnuemotachs used today have great sampling rates, sensitivity ratings that can pick up just a faint heart beat, and superb linearity. When they do happen to measure flow between say 1% and 19% of baseline, it's a fairly accurate averaged volume that they're measuring. Of course, that's not to say those flows between 1% and 19% occur at any given statistical prevalence across the SDB population.

Today's differentiation difficulties have largely to to with finding a way to indirectly determine from a superbly-measured flow signal just what might be happening in physiology (Does that very faint heartbeat mean we're seeing a central? Was that subtle wave-shape nuance highly characteristic of slight obstruction?). But at least they're very good at measuring flow these days.

ozij wrote:Bill (and others...),
I always wondered at what looked like PB's idiotic "initial pressure" parameter, which could only be set to equal the min, or go above it. Absurd, in a machine that has ramp in auto mode.

I was reading Rapoport's paper on Caridac Oscillations, and Rapoports patents, and I think I've finally discovered why the "initial pressure" is there, and it's by no means idiocy, on the contrary -it's brilliant.
...
All in all, I think you may have a better chance of less pressure and less aerophagia if you define an initial pressure above 6.
O.

Wow, Ozij.
(This is a double wow day!)

Ozij, I never really spent much time adjusting the settings on my PB420E. I even had to get out the manual to find which setting you were talking about. I got the machine for travel, quickly set it up, looked at the data software output only briefly, and checked/adjusted FL per RG's recommendations. Although I've been using it exclusively for a little while I haven't been monitoring the data at all. I thought it was set for a range of 6-12 cm, but actually it's set for a range of 4-11 cm with CPAP=6 cm. The CPAP setting is the initial setting your refer to. I supposed I must have assumed the "CPAP" setting wasn't used in APAP mode. However, looking at the data I can see exactly what you are referring to. The charts clearly show the pressure bouncing between 4 cm and 6 cm frequently, sometimes staying down at 4 cm for a little while, but then also climbing up above 10 cm and plateauing up there for periods most often between 30 minutes and an hour.

So, yes, my data confirms exactly what you have described, although to be honest, I'd never payed any attention to it before. By the time I acquired the PB420E I was really pretty tired of experimenting with things CPAP.

I guess now I'm gonna have to experiment some more with the PB420E settings. .

BTW, I spent some time looking through the first Rapoport patent. Interesting discussion material there, to be sure.

Regards,
Bill

Well, posts in this thread are going by faster than I've had time to read 'em, much less respond to 'em. I'm about 147 posts behind right now. Out of those worth responding to, I'll start with this one of yours, -SWS.

-SWS wrote: Bill, it only took me a few hours to understand the human factors that went into that single post. By contrast it would have taken someone with better social acumen but a few seconds. Absolutely no need for you to apologize, but I will for delivering humor that just didn't come across right. Den very succinctly underscores that point above.

-SWS, please don't feel any need to apologize. We all bring baggage to this discussion with us, some we're aware of, some we're not. That's just pretty much the human condition.

-SWS wrote:I ain't never going to learn to dance right, Bill.

I know what you mean. I have to deal with my own lacking in social graces frequently. I just do the best I can and blunder through with what needs to be done. I ain't never gonna display anything like your accommodating personality, -SWS.

Regards,
Bill (who actually can dance, BTW)

rested gal wrote:

dsm wrote:So, setting min & max to titration allows the machine to start at that CMS then vary CMS down and up as it sees fit (per algorithm) ? - great find.

DSM

I may be misunderstanding what you are saying there.

When you put an autopap in auto mode, but you set the minimum and maximum pressure to the same number (like "min 8, max 8") the machine will blow just 8 cm H20. Not varying. Blowing 8 as if it were in cpap mode at 8.

But since the operating mode is set for auto mode rather than for cpap mode, the machine will record the usual "autopap" data...including flow limitations data (which cpap mode doesn't look at.)

But in regard to treatment... the autopap set for auto mode at 8 min, 8 max will blow just 8 while it records events. It won't vary the pressure, 'cause it can't. You've leashed it to go no lower than 8 and no higher than 8.

RG,

I realized this just after making the post but was driving off for a breakfast in the countryside.

Re setting cpap mode - I am sure the S8 Vantage I have supplies the full data even when in cpap mode - I'll have to take another look - As mentioned I have a Reslink module & even get snore data.

DSM

Snoredog wrote:

-SWS wrote:...Toward building this theory, does anyone think it's useful to come up with more distinguishing terms? Is it at all useful to attempt to devise distinguishing terms such as "untreated apnea", "residual apnea", "persistent apnea", "extremely persistent apnea"? Or is that type of distinction merely a waste of time for the way you envision this theory progressing?

But how can you have a "residual" apnea?

I would see and call that inadequate therapy, but I would agree and call a Hypopnea or FL or even snore a "residual event" with those falling in line with your thinking on partial occlusion.

When I look at someone's report, I first look at the worst offender of oxygen levels that being apnea, if they exist not high enough pressure used, if they persist and/or don't go away I highly suspect they are central in origin,

then I suggest they pull out their PSG and look for CA's or MA's denoted on that report. But it seems reporting of CA's on PSG's seem to be subjective on the part of the PSG tech/scorer because many times they have NO CA's denoted on the first PSG but when the patient mentions them they suddenly appear on their 2nd or 3rd PSG (especially if the patient has mentioned those to the tech prior to the study, its akin to the tech saying he/she mentioned centrals, I better pay better attention and score those if seen).

Once the apnea has been addressed with adequate pressure, I look at those "residual" events such as snore, hypopnea and FL and continue with pressure until they dissipate. It seems to me if AI is higher than 1.5 on these autopaps you haven't gone far enough in addressing them, you have to get below AI=1.0 before those "residual" events begin to fall (my experience anyway).

Only curve in that as mentioned is if I suspect the machine is not correctly scoring those events and confusing them for something else as in the case of that NRAH.

My thought process is the machine is LESS accurate in differentiating those residual events like hypopnea and Fl, snore is easy to spot even by the machine. If a machine cannot score a snore accurately you might as well toss it out the window.

But exactly what do you mean by residual apnea?

I'm not sure defining pretreatment terms and post-treatment terms serve what Doug and Bill have in mind toward this theory in the making. However, for the sake of this limited discussion point alone, I would say that anything left over, despite PAP treatment, can be thought of as residual--including apneas.

But your analytical point really sounds as if you suspect everyone should be able to better manage their AI below say 1.5, by selecting better machine settings or a more suitable machine (presumed point 1).

The other points that I think I may be picking up from your post is that if it is a left over apnea, then it must be a central apnea that didn't get differentiated properly (presumed point 2). Or that if there's a residual apnea, then it is probably a central apnea that was pressure-induced--- because some combination of FL/H/S handling probably caused an unnecessary pressure hike (presumed point 3).

Not sure if I summarized those three points completely right to be perfectly honest. But I'll compare views on all three in case I interpreted one or more correctly (so here are my own opinions below):

point 1: All too often not possible for a variety of reasons in physiology, but good tweaking quite often solves that problem---perhaps even more often than not.

point 2: I think residual OA and purely incidental CA tends to show up in the OSA population; but in the case of undiscovered CompSA, "induced CA" rules the order so to speak.

point 3: I suspect this can, indeed, be problematic for people on APAP algorithms that don't suit them well for a variety of possible reasons; It's tough to guess just how often this scenario happens IMO. We've seen plenty of flagrant pressure runaway. So how about unnecessary moderate pressure hikes that are much harder to observe, yet adversely impact residual scores?

I also think it's inordinately difficult to project APAP success or failure rates across patient populations relying on analytic methods such as logic (for lack of much-needed epidemiology). It's not so much that APAP boxes are overly cryptic. Rather the genetic expressions of disease and physiology manifest in an entirely diverse manner of etiology/pathology IMO. .