ASV vs CPAP - and the winner is...

The Latinist wrote: It's hard to draw much of a conclusion from this because you had huge leaks corresponding to your increased pressure and your main cluster of centrals. Did the centrals cause the increase in pressure and therefore the leaks? Or did the increase pressure cause the leaks which caused the increase in centrals? And whichever started the cycle, if you'd not had the leaks would your BiPAP have kept the centrals under control?

Those leaks weren't huge at all. Never even hit 10 L/min. SleepyHead is making mountains out of molehills due to scale. You should have seen the leaks we were seeing when I first saw Benny's reports...now those were massive....80 % of the night over 30 L/min.
And yes he has still had reports with massive central clustering with no leaks to speak of and also with no increase in pressure to speak of.
Centrals won't/don't/can't cause an increase in pressure with the machine that Benny is using right now...so that pressure increase isn't a response to centrals. His machine right now won't respond to centrals at all but instead responds to some sort of obstructive in nature event...flow reduction, snore, etc.
APAPs won't/can't respond to centrals if that is all that is happening. It's the way their algorithm works. They ignore centrals because more pressure from them can't fix the central problem and might make it worse. If we see pressure increases in the neighborhood of a flagged central it is because of some sort of obstructive event that is also happening at about the same time.

The only machines that actually have an algorithm designed to respond to centrals are the ASV type of machines. They respond with a rapid increase in pressure that far surpasses the speed of the APAP machines to increase the pressures.
Like 8 cm to 22 cm in 20 seconds...where as with the APAP machine it might take 2 minutes to get to 22 cm..maybe longer.
APAPs just can't respond high enough and fast enough to address centrals after the fact.

Bilevel machines (the regular kind and not ASV kind) are sometimes able to keep centrals at bay more as a by product of the pressure settings not triggering the centrals in the first place than fixing them after they happen. Prevention as opposed to responding to and trying to fix them after the fact.

jnk wrote:One big problem with centrals can be the night-to-night variation, I understand. Occasional good nights and occasional bad nights seem to be the rule. The system of a one-night diagnostic study doesn't seem to work so well with people with varying central tendencies, I don't think.

I think a bigger issue than attempting to "treat" centrals is finding the cause, whenever possible. Personally, if I continued to have nights full of centrals, I would be asking my doc whether it would be good to look into why they are occurring. If a cause can be known, that can play a role in treatment choice, I believe.

I couldn't agree more and that's why I say "talk to the doctor"....and why I am still seeing red about 108 centrals on a diagnostic study with 12 OAs and he's given an OSA diagnosis and sent home with a machine and had no follow up and no mention as to "BTW those 108 centrals might mean something else is going on that needs investigating because that number of centrals isn't exactly something everyone has so we ignore them"
They aren't pressure induced if they occur without cpap pressure. They are either from something else or maybe idiopathic centrals but they needed to be investigated and at least followed up on.

The Latinist wrote:

Bennnyp wrote:I'm not exactly following this conversation, but here is last nights data. I hope to get my asv soon. I hope it will help with the centrals. I will say that even though my ahi is high.
since lowering my pressures I feel considerable better. Hmmm.

http://s743.photobucket.com/user/Bennny ... 4.jpg.html

It's hard to draw much of a conclusion from this because you had huge leaks corresponding to your increased pressure and your main cluster of centrals. Did the centrals cause the increase in pressure and therefore the leaks? Or did the increase pressure cause the leaks which caused the increase in centrals? And whichever started the cycle, if you'd not had the leaks would your BiPAP have kept the centrals under control?

The leaks are NOT "huge". Look at the scale in SleepyHead. The maximum value on the vertical axis of the leak graph is a measly 10 L/min, which is WELL below the Resmed Redline of 24 L/min for Large Leaks.

So yes, there's some moderate leaking going on at the time the centrals start, but the leaks are not "huge".

Also the increase in pressure just at the start of the cluster of centrals is easily explained: There are at least two closely spaced OAs scored right at the beginning of the dense cluster: Look for the two light blue ticks on the OA line of the event table that are scored right before 5:00; that's exactly when the machine decides to bump the pressure up from 11/7 to 13/9. And the moderate sized leaks start with the 2cm increase in pressure, as do the centrals.

Here's my take on what's going on here:

The machine scores at 2 OAs just before 5:00 and increases the pressure accordingly from 11/7 to 13/9. There may also be some flow limitations or snoring being scored at the same time; we can't tell since we don't have those two graphs.

The increase in pressure triggers some moderate leaks (with a max of 10 L/min, so they are NOT Large Leaks).

The pressure itself MAY be causing the centrals---if Bennnyp's threshold for pressure induced centrals is somewhere around 13/9. Or the moderate leaks may be causing some significant restlessness with some sleep/wave/junk breathing that's being misscored by the machine as CAs. There's no way to really sort this out with just this one day's graph.

In light of both the CAs being scored AND the moderate leaking going on AND the fact that there are no more obstructive events being scored, the S9 starts LOWERING the pressure a little after 5:00. The centrals continue to be scored (and the moderate leaks continue) until the pressure is back down to about 10/8 at around 5:25 or so. There's an isolated H scored at this time, which does NOT trigger a pressure increase because it's isolated.

There's another OA (or 2) scored a bit after 6:40 which triggers another pressure increase and a few more centrals happen before Bennnyp turns the machine off for good around 7:00.

Here's another one.

http://s743.photobucket.com/user/Bennny ... c.jpg.html

Pugsy and Robysue are, of course, correct; I missed the scale on the graph. So the leaks are moderate and unlikely to have interfered with therapeutic pressures. It seems then, that you have a bunch of centrals which correlate with the pressure increase and may be caused by it. If this is a pattern, then it's not surprising that your doctor thinks it needs to be dealt with. I would definitely do your new sleep study and see what the results are.

Pugsy wrote:

jnk wrote:One big problem with centrals can be the night-to-night variation, I understand. Occasional good nights and occasional bad nights seem to be the rule. The system of a one-night diagnostic study doesn't seem to work so well with people with varying central tendencies, I don't think.

I think a bigger issue than attempting to "treat" centrals is finding the cause, whenever possible. Personally, if I continued to have nights full of centrals, I would be asking my doc whether it would be good to look into why they are occurring. If a cause can be known, that can play a role in treatment choice, I believe.

I couldn't agree more and that's why I say "talk to the doctor"....and why I am still seeing red about 108 centrals on a diagnostic study with 12 OAs and he's given an OSA diagnosis and sent home with a machine and had no follow up and no mention as to "BTW those 108 centrals might mean something else is going on that needs investigating because that number of centrals isn't exactly something everyone has so we ignore them"
They aren't pressure induced if they occur without cpap pressure. They are either from something else or maybe idiopathic centrals but they needed to be investigated and at least followed up on.

Sadly, all too often doctors happen to have a hammer, so assume the world is made of nails! ... I even had one neurologist (who should know better) tell me that central sleep apnea is very rare, so I can not have it. I asked "Does the data show that I have central apneas?". He said, "It does. But it's very rare, so you can't have it.". I then commented and rhetorically asked: "Most people miss when they shoot at someone. Would you mind if I pointed at gun at you and pulled the trigger?" I then explained to him that just because the average situation says I do not have a condition, does not mean that in the specific that is true. Rather it's the diagnostic tests that should drive the diagnosis - not the average situation. The old diagnostic saying "If you hear hooves, think horses" does NOT say "If you hear hooves, only think horses ... and always ignore the possibility it might be zebras or bison or elk or ...".

Needless to say that doctor is no longer my doctor.

So unfortunately, some doctors don't understand central apneas so assume it's not an issue. Even a few minutes of looking at the data should have raised red flags in this case.

As to finding the cause, that's a more problematic issue - especially since it is there without the CPAP and he only has mild to moderate obstructive sleep apnea. Sometimes obstructive sleep apnea (especially on the severe side) will trigger the central sleep apnea. Thus, treating the OSA helps treat the central sleep apnea. But in this case with fairly mild obstructive sleep apnea that's not the case. If there are no other clear neurological symptoms the diagnosis would be ideopathic central sleep apnea. In other words, the diagnosis is "Who knows?! He just has it!". Even if there are other neurological symptoms present, there's nothing that can be done to "fix" it. .. Unless of course you go with the new breathing pace maker. But even that is not a fix, just a way of making the body behave better than it does on its own.

If I had a string of PSG centrals but few obstructives in a diagnostic, I would want a cardiac workup, myself, and a test or two, before settling on "idiopathic." I would even want that if habitus or drug history or pain or other health issues seemed the obvious culprit for hypoventilation.

And my point about APAP is that even if the machine is reacting "properly" in the context of simple OSA, it may be reacting improperly in the context of someone with central tendencies. Sometimes it isn't the pressure but the changes in pressure that set things off, especially changes in pressure in conjunction with sleep-stage breathing changes and partial airway closures. It is rarely ever, I believe, a matter of an airway either being open 100 percent or closed 100%--it is often partial closure with both "obstructive" and "central" apneas according to machine definitions, and I believe that gets lost in the context of home-machine-algorithms and the absence of effort belts, because it is an inconvenient thought when looking at home-machine squigglies.

JohnBFisher wrote:So unfortunately, some doctors don't understand central apneas so assume it's not an issue. Even a few minutes of looking at the data should have raised red flags in this case.

I am so hoping that this isn't the case here with Benny since he is going back to the same doctor/sleep lab (I think) that was used initially in hopes that a better job is done this time around but it makes me wonder. I think it was easier to try this guy again instead of hunt for a new doctor and all the time that is involved with that.
I just about choked when I saw the actual dictated sleep study report. Totally ignored the centrals.
From what I gather I suspect we are probably looking at idiopathic centrals in this situation but I don't have all the medical history or details or whatever beyond some basics like no known meds or drugs that might suppress the respiratory system.

Any indication of how much the centrals in the diagnostic disturbed sleep or lowered O2?

jnk wrote:Any indication of how much the centrals in the diagnostic disturbed sleep or lowered O2?

I don't remember but I don't think it was even mentioned...can't be sure. Nothing that stood out though.
It was a very abbreviated dictated summary. Not the complete sleep study showing times and sleep stages and O2 in various stages or position or anything like that. Maybe a page and half long if that.
Not sure I still have it to review but I will look. It may be in my old emails somewhere.
Edit:
This is all I have
"Desaturations were as low as 80% but total desat time was 18.8 minutes"
Bear in mind that the split study pre cpap was only 86 minutes of sleep per the document....
Total recording time was 395 minutes and sleep time much less than that and not the entire diagnostic time that I mentioned earlier. I had a brain fart from the CRS thing.
108 centrals in 86 minutes bears a mention IMHO in the diagnosis line..duh....

Benny...if you don't mind I will post what you sent me but omit all the personal information. This way others can see what I saw. It may be back in your Photobucket account somewhere because Sludge mentioned the 86 minutes sleep time.
If this is a problem for you just let me know and I will remove the images and I apologize in advance but the others haven't seen it.

I don't understand that diagnosis at all. If you ignore the centrals, his AHI is 13.9. Hardly "severe" OSA. And to completely ignore the central apnea seems like malpractice.

The Latinist wrote:I don't understand that diagnosis at all. If you ignore the centrals, his AHI is 13.9. Hardly "severe" OSA. And to completely ignore the central apnea seems like malpractice.

And now you know why I was seeing red and bitching and complaining and rolling my eyes. I understand typos and doctors getting words backwards and all that but this takes the cake. Even my own dictated summary report was more helpful than this one and sure as heck made more sense. Makes me wonder if it was even read after it was typed up.

Not to mention I spent 2 to 3 months bitching at Benny to clean up his leaks before we worry about the centrals which back then were coming in massive numbers with the pressures in the 20s that he was using...I didn't see this report until not long ago or I would have thrown a fit sooner. So I feel bad that I wasted months trying to fix leaks at the high pressures first but he was mouth breathing...sigh....hind sight is always 20/20. I thought the doc prescribed the hurricane pressures for a legitimate reason so that was what I was trying to make work.

I am in no position to defend the doc, because I have no letters after my name. But that doesn't stop me from being presumptuous enough to comment . . .

The doc did say another sleep study was needed after the split night, noting what was basically a failed titration.

And often the purpose of the first part of the split-night is just to see something that qualifies the patient to try a machine.

And they did try bilevel, which might not happen at every clinic.

And CompSAS was basically differential-diagnosed out of the picture right away.

And although it is a classic cop-out, the doc did at least say, "Patient will need to follow up with his physician to discuss this finding and determine a plan . . ." Classic case of crack-falling and run-around, maybe, although some insurance situations sort of require that. The doc is saying --I may never see this patient again, so tell the primary this--. Problem is, how many primary docs would recognize the significance of "persistence of sawtooth pattern"? Doesn't quite cut it in my book. Not enough of a flag and not red enough.

On the other hand. (Wait, how many hands have I used already?) Doc never saw any REM in the first half and may have assumed the central issues were mostly from damage done by obstructive problems the doc never got to see.

I hate split-night studies. And I blame insurance for them. It forces a doc to fly blind, since the end-of-the-night data is often the most valuable data for diagnostics, and that can't be gathered when titration is already in swing.

Thanks for posting that Pugsy. It was educational for me.

And I sure appreciate your approach to things on this board. Glad you're here.

jnk wrote:

Todzo wrote: . . . tracheostomy . . . central apnea . . .

May unmask, but will not cause.

I have often wondered if some sleep apnea may well be caused by changes in the breathing control system and this is likely evidence.

Perhaps some obstructive sleep apnea develops in response to the breathing control system problems.

Adding air pressure would do the same as a tracheostomy by removing the obstruction and increasing the gain as well by making inhalation easier (with exhale is assisted by well developed "talking" muscles, gravity (the weight of the belly pressing down), and/or tissue tensions).

I do not believe we will ever, therefore, see any kind of variable pressure device deal well with hypocapnic central apnea as in CompSAS.

Keeping the carbon dioxide level from dropping below the apneic threshold[1,2] looks like the only way currently available to actually prevent the central apneas from forming without causing excessive arousals. So I do believe it is time for the industry to look more in this specific direction.

[1]: Gilmartin G, McGeehan B, Vigneault K, Daly RW, Manento M, Weiss JW, Thomas RJ.
Treatment of positive airway pressure treatment-associated respiratory instability with enhanced expiratory rebreathing space (EERS).
Source: J Clin Sleep Med. 2010 Dec 15;6(6):529-38. Division of Pulmonary, Critical Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Link: http://www.ncbi.nlm.nih.gov/pubmed/21206741

[2]: Dynamic CO2 therapy in periodic breathing: a modeling study to determine optimal timing and dosage regimes
Yoseph Mebrate, Keith Willson, Charlotte H. Manisty, Resham Baruah, Jamil Mayet, Alun D. Hughes, Kim H. Parker and Darrel P. Francis
J Appl Physiol 107:696-706, 2009. First published 23 July 2009; doi: 10.1152/japplphysiol.90308.2008
Link: http://www.ncbi.nlm.nih.gov/pubmed/19628721

jnk wrote:And although it is a classic cop-out, the doc did at least say,

I hear you and I noted that also...I wasn't privvy to what all may have gone on in any discussions with the PCP and Benny.
Maybe Benny didn't scream loud enough...maybe Benny didn't scream at all..maybe he kept getting the "give it time" thing.
I don't know and I really don't care at this point. I worked in the medical field for over 30 years and this sort of falling through the cracks or like JohnBFisher's first doctor simply not thinking centrals were a problem...shouldn't happen. I know they do but they shouldn't and the sad thing is...they don't have to if someone would just get off their lazy ass and do something.
He should have been rescheduled right then and there IMHO because they came no where close to resolving any issues at all.
No one did any follow up...I suspect each one would point the finger at the other. I point the finger at all of them.
And if Benny didn't ever bitch about it to anyone...he gets a little of my finger pointing to. Hell, I even point my finger at myself for not catching this sooner. I got fixated on leaks and hoping all those centrals were arousal centrals from leaking.

That's water under the bridge though. Can't fix what happened or didn't happen yesterday but I won't go making excuses for someone that does a half assed job. Let's just try to get it right this time ...hopefully.