Message for Avi

If this helps I changed my CPAP for an APAP after just 1 month under Medicare.....My DME tried to stop it but I won in the end.

avi123 wrote:Jan, sorry about it. I 'll try to fix it. Here is my message:

Upgrade my CPAP to APAP under Medicare rental arrangement

Sent at: Wed Apr 27, 2011 4:30 pm
From: avi123
To: Janknitz

Hi Jan, by any chance do you know if under Medicare rental I can change my CPAP to APAP?

I am in the 6 month of rental under Medicare. My DME on its own changed the S8 Escape II with S9 Elite in the third month of rental. But my AHIs are still high and I need higher pressures to counteract the Obstructive and not burden the Centrals. My sleep doctor MD gave me an RX for an S9 Autoset. But the DME (who is Medicare provider) emailed this to me:
*********************************************

Mr. Avi, YYYY contacted me regarding your request for a new auto cpap unit. We have already evenly exchanged your cpap unit once, which is not our policy, because you are a valued customer that we want to help. Your insurance did not cover this exchange, as insurance companies do not allow that practice and do not cover any expenses incurred. {this sort of correct. The DME was denied payments more than 20 times as "Duplicate service-previously processed}

If you would like to cash purchase an auto cpap, we have very competitive pricing—around $1000 for both the flow generator and humidifier. We are happy to help you in this manner, but are unable to do another exchange of a used unit for a brand new one. Insurance companies will not recognize a physician’s order as a reason to cover another unit for you.

Thank you for your email and please let us know how we can help from this point forward.


Clinical Manager

*******************************************************

Jan, any idea how to go about it? Reminding you that I am using a CPAP being amortized at Medicare for the 7 more months.

I read your reports but I don't think that a similar case is covered there.

I am fully covered by Medicare and Medigap.

Thanks.

Avi

avi123 wrote:Please clarify this:

You wrote: "You are also mistaken in assuming the Autosed will "drop the pressure" if it encounters a central apnea. It will do no such thing. After an apnea it condsider obstructive, an Autoset will raise the pressure. After a central apnea it will simply not make any changes. "

If I set the S9 Autoset at 8 cm low and 12 cm hi, what will it do if it encounters Obstructive Apnea vs. Central Apnea?

Let's say the apnea in question occurs when the Autoset is running at a pressure setting of 11cm.

If the apnea is an OBSTRUCTIVE apnea, the Autoset will INCREASE the pressure from 11cm up to a point where the flow curve is decent and no further OAs are occurring. In a worst case scenario, the pressure may be increased all the way to the max allowed (12cm in your case). Not sure if the S9 starts increasing the pressure AFTER the apnea is OVER or just after the machine's algorithm has determined the apnea is an OA. But unless the apnea is a really long one, we're only talking a matter of a few of seconds or so anyway.

If the apnea is a CENTRAL apnea, the Autoset will simply continue running at a pressure of 11cm: Until and unless OTHER events such as flow limitations, snores, and obtructive apneas start to occur and cause the pressure to increase. So if a central apnea occurs very close to a significant flow limitation, the machine won't respond to the CENTRAL, but it may very well start increasing the pressure due to the Flow limitation and if you're only looking at the pressure graph and the events graph, you could mistakenly attribute the increase in pressure to an incorrect response to the Central.

The S9 Auto begins to REDUCE the pressure from the current setting when: (a) Any flow limitations have been adequately dealt with, (b) snoring has been reduced, and (c) no clusters of OAs are occurring. Typically the S9 starts gently reducing the pressure setting as soon as the event(s) that triggered the increase are addressed. Hence the sharp peaky-wave look to the S9 AutoSet's pressure curves. And if you happen to have a Central right after a flow limitation or snoring event that triggered a pressure increase is resolved and you're only looking at the Events graph and the Pressure graph (and not the flow and snore graphs), it can be easy to mistakenly attribute that decrease in pressure to the Central. But that's simply not the case: The pressure decrease is because the event that triggered the initial rise in pressure has been addressed and the machine is happy with the flow curve and snoring index and no OAs are occurring.

Hi robysue, my main objective in replacing my S9 Elite which is a plain CPAP with the S9 Autoset is this:




Notice here in the Flow graph taken from my S9 Elite, that a pressure of 9.6 cmH2O has not taken care of an Obstructive Apnea that occurred to me:

Re-edit: But, I seem to have an error here b/c the the flags are usually posted at the ends of the events and this is not the case here.


Should I raise the pressure to take care of such Obstructive Apneas it could affect my Central Apneas negatively. The S9 Elite does not change pressures b/c of Apneas.


On the other hand, if I switch to S9 Autoset, then this machine would raise the pressure to take care of Obstructive Apneas but when it detects Central Apneas (i.e. open airway) with its FOT it should keep the pressure below 10 cmH2O. This I read in this Resmed's report:

Central Sleep Apnea Detection and the Enhanced AutoSet Algorithm

J P Armitstead, PhD; G N Richards, MB ChB; A Wimms, BSc; A V Benjafield, PhD
Applied Research and ResMed Science Center, ResMed Ltd, Sydney, Australia


Link:

http://www.resmed.com/us/assets/documen ... -paper.pdf

The following illustrations taken from this report explains it visually:




Note: at this point I am not interested how the S9 Autoset does it as long as it does not expose my Central Apneas to hi pressures.

Thank you Avi for providing the link to ResMed's paper about verifying the accuracy of the enhanced Autoset's Central Sleep Apnea Detection and response.

Please show me where it says in this paper that the Autoset reduces pressure in response to central apnea.

In describing figure 5, Resmed wrote: Another subject treated with the enhanced AutoSet and
CSAD experiencing central apneas at a pressure below
10 cm H2O is shown in Figure 5. The pressure has not
increased. The previous algorithm would have increased
pressure to 10 cm H2O.

Please look at your data, Avi.
You experience many obstructive apneas and flow limitations at your present 9.6 pressure. These apneas, and the flow limitations will make an Autoset raise your pressure higher and higher.

Now look at your data again:
You experience central apnea and unknown apneas at pressures lower than 10.
If your central apnea are pressure induced, they will become worse as the pressure rises higher and higher in response to all those obstructive apneas and flow limitations.
If, on the other hand, your central apneas are post-arousal central pauses, the resolution of your obstructive apneas will result in a reduction of those central apnea.

So you really have to consult your doctor before setting up the Autoset.
Please ask him to read this paper which discusses the accuracy of the Autoset's event detection.
And then, please ask your doctor how he understands the central events reported in your results.
Ask him if the thinks your central apneas may disappear when the obstructive component is solved. Ask him if, on the other hand, he thinks it may be possible that your central apneas will multiply as the pressure goes up in response to the obstructive triggers [apneas, snores, flow limitations].

Ask him, also if he thinks it's possible you may be suffering from Complex Sleep Apnea Syndrome, and if so, how long does he want you to try to adapt to CPAP, before having you titrated on an ASV machine.
Do keep in mind the fact that people who suffer from CompSAS do not do well on Automatic algorithms.

And I'll repeat my question: please show me where it says in this paper that the Autoset reduces pressure in response to central apnea.
The figures you've provided support my previous statements:

• The ResMed Autoset algorithm does not reduce pressure in response to an apnea it identifies as central. (Caption to Figure 5: "A subject with central apneas and the enhanced AutoSet and CSAD algorithms not increasing pressure").
  
  An APAP does drop pressure if it sees you breathing smoothly for a while. (Fig. 3 and Fig. 4)

ozij wrote: Ask him, also if he thinks it's possible you may be suffering from Complex Sleep Apnea Syndrome, and if so, how long does he want you to try to adapt to CPAP, before having you titrated on an ASV machine.
Do keep in mind the fact that people who suffer from CompSAS do not do well on Automatic algorithms.

AVI, I have been wondering the same about your residual AHI. I'm glad ozij mentioned that possibility...

Avi,

First and foremost, I agree with ozij and -SWS: You absolutely NEED to talk to the sleep doctor about your residual AHI, the fact that you still have numerous events, some central, some not occurring at your current CPAP pressure of 9.6, the possibility that you have CompSA, and the very real fact that you may need to be on an AVS. You should ask point blank: How long does the doctor want you to continue with your current ineffective treatment before declaring CPAP is not enough? The question is relevant since Medicare requires you "fail" at CPAP before they'll pay for a more fancy machine. But how long you try depends at least in part on when the doctor is willing to put in writing that you've tried and failed at CPAP.

Next, thanks for link to ResMed's paper about verifying the accuracy of the enhanced Autoset's Central Sleep Apnea Detection and response.. But I still think you are not reading the paper closely enough.

First, on page 1, the paper states:

Automatic algorithms respond to the presense of apneas (assumed to be obstructive) by raising delivered pressure because, although this does not treat the apnea that is detected, the pressure increase reduces the likelihood of further obstructive events occurring.

This makes it clear that in any Auto algorithm, the INCREASE in pressure due to an obstructive apnea does NOT "blast" through or "open" the current (obstructive) apnea. Rather---with the increase in pressure, the likelihood of future OAs goes down.

Second, on page 2, the paper states:

The CSAD (Central Sleep Apnea Detection) algorithm determines resistance of the upper airway. To do this accurately the impedance of the circuit needs to be known. CSAD works optimally when recommended circuit configurations are used, but it does not rely on correct menu setup. The ability to determine resistance is also affected by large leaks. Small leaks are tolerated but the accuracy falls rapidly with leaks greater than 30L/min.

Apneas are classified as being central (open upper airway), obstructive (closed upper airway) or unknown. Central apneas are scored when the resistance is low, and obstructive apneas when the resistance is high. The classifier labels apneas 'unknown' when the inadvertent leak exceeds 30 L/min or the resistance is indeterminate. Central and unknown apneas do not cause an increase in delivered pressure (emphasis added)

So the CSAD algorithm (based on the FOT algorithm) that's being used to enhance the AutoSet determines two things:

• (1) How to score the particular apnea: The apnea is scored as an OA because of a CLOSED airway OR the apnea is scored as a CA because of an OPEN airway.
  
  (2) Whether to increase the pressure: If airway is CLOSED, increase pressure---regardless of what current pressure level is; if the airway is OPEN, do not increase pressure---regardless of what current pressure is. And note: "does not cause an increase" is not the same as "decrease.

Finally, you write:

Note: at this point I am not interested how the S9 Autoset does it as long as it does not expose my Central Apneas to hi pressures.

As ozij points out, your current fixed pressure on the S9 Elite is 9.6. And your flow limitation graph shows some pretty significant flow limitations going on most of the night at your current pressure. Since those flow limitations ARE used by the S9 Enhanced AutSet algorithm to increase pressure, on an S9 Auto, your pressure would likely rise above 10cm in order to resolve the flow limitations. How often and how high? And enough to "expose (your) Central Apneas to hi pressures."? I'm not a doctor or an RT. So I don't know. That's why I second ozij's suggestion that you talk about all of this with your doctor and even bring in this paper with you.

As it was explained to me in simple terms, an auto will not raise pressure to "eliminate" an event already in progress but to "prevent" further events. So if the minimum pressure is set high enough the first event may not occur at all. The max should be set 1-2cms above 90% to catch any stray events that may occur during REM or deep sleep/dreams stage. I think I have that right?

del

While this is not exactly related to avi's predicament, I am trying to understand the concept that higher CPAP/APAP pressure does not open an airway, but it can make an obstructive apnea shorter.

If the higher pressure doesn't assist in some way with opening the airway, how can it shorten an event?

I have personally noticed fewer obstructive events with higher pressure, which I can understand under the stent premise. But I have also noticed shorter events with the higher pressure, which I can't explain under the stent premise.

Can someone explain?

Thanks!

John

Hi John,
Suppose your airway is not stented.
Your muscles relax, your airway collapses. You've got a 30 second apnea.
Now think of the same apnea, but stent the airway with pressure.
Your muscles relax, the pressure keeps your airway from collapsing, this works for about 15 seconds
Your muscles continue relaxing, against the supplied pressure.
Now the pressure is no longer enough, your airway collapses. However, for 15 seconds, the pressure worked, and now you've got a 15 second apnea instead of a 30 second one.
The pressure doesn't "cut the apnea short " after it starts. Rather, it supplies the resistance that delays the beginning of an apnea..
The effect, time-wise is a "shorter apnea' but it's shorter because the stinting kept it from happening for part of the time.

Ozij, you're "stinting" instead of "stenting"! I needed that laugh!

Avi123 wrote:3) Last week, while talking to my sleep Doc who happened to have MDs in both Pneumatology and Internal Medicine and who is a Diplomate in Sleep Medicine, ABIM, and is the one who interpreted the above PSG tests, we have decided that I should try an APAP for a couple of months to see if it does lower my AHIs. If not then a new PSG might be in order. This Doc is not interested in CPAPS results for analysis of events or Graphs because CPAPs rely on Flow only. The Doc was interested in my feeling and my two daily half hour naps because of residual daytime sleepiness.

I take that to mean the Doc who happenes to have MDs in both Pneumatology and Internal Medicine and who is a Diplomate in Sleep Medicine, ABIM is concerned about your total AHI and is aware you have further symptoms of untreated sleep apnea which he would like to improve.

The caridiac PVC noted in the PSG concerns me. This is one reason for my wish to avoid hi pressures going into my Central Apneas.

This too should be discussed with your sleep Doc who happens to have MDs in both Pneumatology and Internal Medicine and who is a Diplomate in Sleep Medicine, ABIM.

ozij wrote:No cpap - fixed or auto - will "open" an apnea. Continuous Positive Air Pressure is there to stent your airway and keep it from collapsing, but if it collapses, it collapses. With proper pressure, in garden variety OSA, most obstructive apneas will be prevented - or perhaps be shorter, but none are "opened".

You are also mistaken in assuming the Autoset will "drop the pressure" if it encounters a central apnea. It will do no such thing. After an apnea it considers obstructive, an Autoset will raise the pressure. After a central apnea it will simply not make any changes.

You have got many flow limitations - these are going to drive the Autoset's pressure up -- in an attempt to get rid of them. The Autoset is very responsive to flow limitations.

Avi123 wrote:4) I do keep reading that the S9 Autoset besides identifying and treating OI, with over 10 cm H2O, also responds to flow limitations and snoring, with above 10 cmH20, increases pressure only during inspiration and not during apnea, and also does not increase pressure for central apneas, as several posted above.

I guess we are all in agreement now about how APAP's function, and about which of the posters misread, misunderstood or misremembered what the ResMed paper said.

BTW, for me to comment on your typos would be a case of the pot calling the kettle black Avi, but I really can't help wondering, when you write: "Here is one of my ResScan graphs which buffled me but not the Doc" would you consider that a "grammar mistake" or a typo? IMO, it's a typo, the word is BAFFLED not BUFFLED.

Good luck in your therapy!

DoriC wrote:Ozij, you're "stinting" instead of "stenting"! I needed that laugh!

Ah Dori, in this I bow to the higher authority of those venerable internet sources, Google's spell checker, and -SWS - both of whom are incredible resources of valid information...
So when google spell check corrected "stenting" to "stinting", and I remembered -SWS using it, I figured it was 2 against 1...

What's the old saying.... "Two wrongs don't make a right?"

ozij wrote:Hi John,
Suppose your airway is not stented.
Your muscles relax, your airway collapses. You've got a 30 second apnea.
Now think of the same apnea, but stent the airway with pressure.
Your muscles relax, the pressure keeps your airway from collapsing, this works for about 15 seconds
Your muscles continue relaxing, against the supplied pressure.
Now the pressure is no longer enough, your airway collapses. However, for 15 seconds, the pressure worked, and now you've got a 15 second apnea instead of a 30 second one.
The pressure doesn't "cut the apnea short " after it starts. Rather, it supplies the resistance that delays the beginning of an apnea..
The effect, time-wise is a "shorter apnea' but it's shorter because the stinting kept it from happening for part of the time.

Great explanation!

Thanks a lot!

John

rested gal wrote:What's the old saying.... "Two wrongs don't make a right?"

No, but three lefts do!