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CA's, Mask type, and leaks/vent
#1
Question 
I have been pouring over sleepyhead data and trying to find some relationship between my CA's and any other data on sleepyhead.
Most of my CA's happen the last 4 hours of the night when I am half asleep. I get that and classify them as SWJ. Junk or not, I have to stop them. I believe my O2 drops too low and wakes me up. I caught one time at 86%.

What I have also noticed was that when a cluster of CA's happen, I also have no mask leaks.

Another observation is, I am using the P10 system and there is no free space in the mask to dampen the pressure changes.

My question is - Can a FFM or Nasal mask with more free space be easier on the CA's and sudden pressure changes?

Following the discussions on EPR, CA's and etc. it seems that the people with the pillows have a bigger problem. Could be my imagination so you are free to "Correct me if I am wrong"
Dont-know  I am an accountant so any advice given here is not medical. If I give any financial advice, you can take it to the bank. However, you will have a hard time cashing it in. Okay
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#2
(11-13-2016, 08:19 PM)Rcgop Wrote: I have been pouring over sleepyhead data and trying to find some relationship between my CA's and any other data on sleepyhead.
Most of my CA's happen the last 4 hours of the night when I am half asleep. I get that and classify them as SWJ. Junk or not, I have to stop them. I believe my O2 drops too low and wakes me up. I caught one time at 86%
Did either your diagnostic or titration sleep tests say anything about CAs?

Quote:What I have also noticed was that when a cluster of CA's happen, I also have no mask leaks.
How many CAs are we talking about? And how long do they last? And what does your leak line look like the rest of the night?

Also there's no good reason to assume that "no leaks" is what's causing the CAs: The Resmed machine you are using records only the unintentional leak rate and it's actually expected that if the leaks are well controlled, the leak rate should be reported as 0 L/min for most (even all) of the night.

Quote:Another observation is, I am using the P10 system and there is no free space in the mask to dampen the pressure changes.

My question is - Can a FFM or Nasal mask with more free space be easier on the CA's and sudden pressure changes?
I don't know what you mean by "dampen the pressure changes." Do you mean "less noticeable"?? Or do you mean something else?

It is true that the space in a nasal pillows mask is somewhat less than in a nasal mask and significantly less than the space in a larger nasal mask or a FFM, but all the space inside the mask is pressurized regardless of what kind of mask you are using.

When the machine feels the need to increase the pressure, it's going to pump enough air into the whole system to make all the space inside the mask (and your upper airway) have the correct pressure. The more space there is in the mask, the more air the machine will have to pump into the system.

Moreover, the fact that there more space in a FFM typically also means that the engineers have built in a higher intentional leak rate to help make sure that all the air in the mask is exchanged frequently enough to prevent rebreathing of CO2. And that also means that when the machine decides to ramp up the pressure, it will have to pump a bit more air into the system when you are using a FFM as opposed to a nasal pillows mask.

Quote:Following the discussions on EPR, CA's and etc. it seems that the people with the pillows have a bigger problem. Could be my imagination so you are free to "Correct me if I am wrong"
I don't know what you mean by people with nasal pillows have a bigger problem. A bigger problem with what?

I've looked at a lot of data from a lot of people the last six years, and I have not picked up any kind of correlation between using nasal pillows and having more CAs. Moreover the correlation between EPR and having more CAs is rather convoluted: Some people have more CAs withs straight pressure or EPR = 1 than they do with EPR = 3.

In a person who actually has a real problem with pressure induced CAs, whether EPR is or is not a contributing factor all depends on what is causing the CO2 overshoot/undershoot to develop in the first place:
  • If the person has a great deal of difficulty exhaling against the pressure, that may allow the person to retain too much CO2 (undershoot) which triggers hyperventilation (overbreathing), and the hyperventilation leads to blowing off too much CO2, which then suppresses the urge to breathe, which triggers the CO2 undershoot (plus a possible CA) and the CO2 undershoot will lead to the next CO2 overshoot and a positive feedback loop can set up with CAs occurring at the nadir of the breathing cycle.
  • If the difference between IPAP and EPAP is great enough where the person finds it too easy to exhale too fully and too much of the residual CO2 is blown out of the mask's exhaust vents by the positive air pressure, then a CO2 overshoot situation can develop which triggers a suppression of the urge to breathe, which triggers a lessoning of the size of the inhalations and exhalations to correct the CO2 level in the blood, which triggers a CO2 undershoot (and a possible CA) and the CO2 undershoot can lead to the next CO2 overshoot and a positive feedback loop can set up with CAs occurring at the nadir of the breathing cycle.
In the first case, more exhalation relief can actually be useful in preventing the cycle from developing as well as increasing comfort; in other words in this case the number of CAs may go down when EPR is turned up.

In the second case, the person may have fewer CAs if they turn EPR down or off.

And then there's this to consider as well: If pressure-induced CAs don't resolve themselves and the CAs really are present in enough numbers to be clinically significant, then the usual next step of treatment is to try a plain old BiPAP because sometimes the greater difference between IPAP and EPAP is enough to take care of the CAs and they wind up resolving when the person is put on BiPAP with an IPAP-EPAP difference of 4 or 5 cm. Most insurance companies won't automatically move a person with potential problems with mild complex sleep apnea to a BiPAP ST or an ASV machine until a plain old BiPAP has been unsuccessfully tried. And the way that BiPAP ST and ASV machines treat CAs is by ramping up the PS support when it looks like there's a high chance of CAs starting to develop. And what is PS? It's just IPAP - EPAP. In other words, PS is just a variable amount of EPR, where the min PS is usually set up around 3-5cm on an ASV machine.

So I come back to the questions I asked earlier:

1) How many CAs are we talking about? 2 or 3? or more like 7-8?

2) What does your leak line look like for the entire night?

Can you post some data that shows the whole night? Post the flow rate, the pressure curve, and the leak curve.

And then can you zoom in on a CAs cluster that you are worried about? Try to zoom in far enough to see the individual breaths in the flow rate curve. And post the pressure curve and the leak curve with the flow rate curve.
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See my Guide to SleepyHead
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#3
I believe the idea is that the FFM can act as a low pass filter and limit the rate of change of pressure in the system. However, the system is capable of at least 4 HZ pressure changes, since that is used to detect CA' vs OA's I expect the upper end is much higher than that, but from a therapy point of view, the rate of change is orders of magnitude lower. I don't believe any significant damping affects occur because of the increased volume of the FFM.
I am not a Medical professional and I don't play one on the internet.
Started CPAP Therapy April 5, 2016
I'd Rather Be Sleeping
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#4
(11-14-2016, 12:45 AM)FrankNichols Wrote: I believe the idea is that the FFM can act as a low pass filter and limit the rate of change of pressure in the system.
Explain what that means in layman's terms?

Quote:However, the system is capable of at least 4 HZ pressure changes, since that is used to detect CA' vs OA's
That's the pesky FOT that drove me nuts when I was first starting out and using a Resmed S9 AutoSet ....

Quote:I expect the upper end is much higher than that, but from a therapy point of view, the rate of change is orders of magnitude lower.
Yes, the rate the machine increases the pressure when it wants to increase the therapeutic setting is much slower than when it's doing the FOT oscillations.

Of course the amount it increases the pressure by when the AutoSet algorithm is responding to events, flow limitations, and snoring is a lot larger than the amplitude of the FOT oscillations are.

Quote:I don't believe any significant damping affects occur because of the increased volume of the FFM.
But until we actually see some data that shows Rcgop's CAs we really haven't got much of a clue as to why he's even thinking that air space inside his mask makes a difference in the number of CAs he's having.

Questions about SleepyHead?
See my Guide to SleepyHead
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#5
I guess I have some explaining to do. This is exactly the kind of discussion I was hoping for so I will start by trying to better where I am coming from. I am getting frustrated with my AHI numbers. I think there is some O2 desaturation involved so I feel they need to be addressed and not just written off as SWJ even though that's probably what they are. On the positive side I have been feeling better during the day so I feel I am making progress. My afternoon naps (1 to 1 1/2 hrs.) are pure heaven. Always zero events, always on my back the whole time, none to minimal leaks (mouth) and with good sleep. At night, the first half is good and the problem starts the last 3 to 4 hours of the night.

I will try to answer the questions in order:

robysue wrote:
Quote:Did either your diagnostic or titration sleep tests say anything about CAs?

I had a home study with no titration. Given the Apap with 4 to 16 pressure. 35 OA's, 29 HA's and 0 centrals. AHI 7.1 with 7.7 desaturations with a low of 76% . Supine index equals 18.7.

Quote:Also there's no good reason to assume that "no leaks" is what's causing the CAs:

That's not what I am suggesting. I have noticed that when I am sleeping my leaks are well under control and when I am having repetitive CA's, my leaks seem to go up. Not necessarily above the allowed 24 l/min.

Quote:How many CAs are we talking about? And how long do they last?

My AHI is around 2 to 3 most nights. Zero OA's, 1 or 2 HA's, and the rest are CA's and come in bunches when I am half asleep, and had a couple hours of good sleep. I occasionally get an AHI <1 and I have even had a several days with zero events for the whole night. But then again that's in the 9 months of paping. They last from 11 to 20 seconds which is probably not bad but when you string 4 or 5 in a row, it can't be good.

Quote:I don't know what you mean by "dampen the pressure changes." Do you mean "less noticeable"??

Probably dampen. With more space, the pressure will build more slowly. Maybe only by a fraction of a second but not as suddenly. The machine will try to fill the mask to the appropriate pressure as quickly as possible. I am saying, it take a slight bit of time to accomplish this.

Quote:I don't know what you mean by people with nasal pillows have a bigger problem.
Problem is probably the wrong word. When I look at other's charts, I look at their mask type and it seems (to me anyway) that people with FFMs have fewer centrals than those on pillows. Hence the reason for this discussion.

Also a very big thanks to robysue for the detail on what causes CA's. I will read over it many times in the next few days.

Also I will post a typical day shortly. I can't do it on this computer as sleepyhead is on a different computer.

Thanks like
Dont-know  I am an accountant so any advice given here is not medical. If I give any financial advice, you can take it to the bank. However, you will have a hard time cashing it in. Okay
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#6
http://imgur.com/a/dDeEC

Quote:So I come back to the questions I asked earlier:

1) How many CAs are we talking about? 2 or 3? or more like 7-8?

2) What does your leak line look like for the entire night?

Can you post some data that shows the whole night? Post the flow rate, the pressure curve, and the leak curve.

robysue, Here are the graphs that should answer your questions.
The first is the whole night. You can see the first part of the night is reasonably good. The second is a 1 hour nap earlier in the day. (Heavenly I might add). Third is a close up of my problem areas. I might add that the EPR is at one and when I reduce it to "off" I get fewer CA's but more HA's. I have not yet tried EPR any higher than 1 yet. My comfort level went up significantly but with more CA's. Maybe I need to jump to EPR of 3 as a test. Maybe just for a nap at first.
Dont-know  I am an accountant so any advice given here is not medical. If I give any financial advice, you can take it to the bank. However, you will have a hard time cashing it in. Okay
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#7
That hour between 3:00 and 4:00 looks mighty rough. You turned the machine off and back on right before this rough hour starts, so a good question to ask is: Do you think you got back to sleep? Or do you think all you were doing was dozing during this time?

There are two main clusters of CAs between 3:00 and 4:00. One is around 3:05-3:10 and the second is around 3:35-3:40ish. The first one may be represent a particularly rough WAKE to SLEEP transition. If you fell asleep briefly, the second one may also be a sleep transition cluster, but that's hard to say for sure.

You turn the machine off around 4:00ish and then back on again. So you were clearly awake at that point. When you turn the machine back on, there's another smaller cluster of events shortly after 4:15, and then even on the full night scale you can see that the breathing settles down into a clear sleep breathing pattern. So my guess is that the cluster around 4:15 is most likely sleep transitional.

But without knowing more about what was going on between 3:00 and 4:00, it's hard to make sense of that cluster of events.

More pressure---in the sense of changing the minimum and maximum pressure settings is NOT going to fix those CAs and it could make them worse. So leave the pressure settings alone.

You also write:
Quote:I have not yet tried EPR any higher than 1 yet. My comfort level went up significantly but with more CA's. Maybe I need to jump to EPR of 3 as a test. Maybe just for a nap at first.
At this point in your therapy I would say the comfort level is more important than the CAs. I think your CAs are likely to resolve themselves once you are comfortably sleeping with the machine, rather than being slightly less comfortable. The less comfortable you are, the more you are likely to wake and that provides more opportunities for sleep transition CAs to creep in.

Use naps to experiment with EPR. Try EPR = 2 and EPR = 3 on different naps and see if either are more comfortable than EPR =1. If you are more comfortable with a higher EPR, then switch to the higher EPR and use the higher EPR for at least 3 or 4 days before trying to conclude whether EPR is somehow responsible for your CAs.
Questions about SleepyHead?
See my Guide to SleepyHead
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#8
robysue,
Thank you for the excellent discussion on CA's. It all makes perfect sense now.

The times between 3:00 and 4:00 are rough. This is my problem. I start back too sleep and CA'S start up again. I start and stop the machine to mark the spot as well as to try to break the cycle. I have tried tried getting up and walking around, using the ramp feature , or just keeping my eyes open in order to get awake enough to get totally reset. Nothing works the last half of the night.

I have been afraid to change to play with the EPR because when I went to 1 the only change was a change from CA to HA. This would increase pressure and keep me awake. From the discussion on the board, I got the impression EPR would cause CAs.

NOW FOR THE GOOD NEWS!
Last night out of desperation I took the plunge and cranked the EPR to 3. My night was much improved. And my AHI was 1.02 but the best part is only 4 CA's all night. AND, 90% pressure equal to 8.38. AND, when I woke up at 4 (not 3) I stayed awake and was comfortable.

If this is the answer, then I can work on the OAs from last night. I will post the graphs here in a few minutes so you can see what I am talking about. I did stop and start the machine out of curiosity and not because of my comfort level.

Again thanks for the info. Thanks

Dont-know  I am an accountant so any advice given here is not medical. If I give any financial advice, you can take it to the bank. However, you will have a hard time cashing it in. Okay
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#9
robysue,
Here is the screen shot from last night as promised. EPR =3, and much more comfortable night. I think we are onto something good.

I hope this is not a fluke.

Thanks again.
http://imgur.com/a/hA5id
Dont-know  I am an accountant so any advice given here is not medical. If I give any financial advice, you can take it to the bank. However, you will have a hard time cashing it in. Okay
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#10
(11-15-2016, 01:10 PM)Rcgop Wrote: I have been afraid to change to play with the EPR because when I went to 1 the only change was a change from CA to HA. This would increase pressure and keep me awake. From the discussion on the board, I got the impression EPR would cause CAs.
The idea that EPR causes large numbers of CAs in lots PAPers is, unfortunately, a piece of misinformation that does seem pretty common around here.

The fact is that some people do better in terms of the numbers of CAs with EPR turned on and set to 3. Other people do better in terms of the number of CAs with EPR turned OFF. And many people don't notice any difference in the number of CAs when they change their EPR setting

My own pet theory that explains all three things: Except for a small minority of PAPers, the number of real CAs on CPAP is not clinically significant. The literature I've read indicates that no more than 15% of new PAPers develop clinically significant numbers of CAs once they start PAPing. And even among the ones who do, the problem is self-limiting: As their body adjusts to PAP and as they learn to sleep more comfortably with the mask on their nose, the number of machine scored CAs goes down with time. And so many of the PAPers who do have problems with CAs initially are no longer having problems with them 2 or 3 months after starting therapy.

I don't discount potential problems with CAs in newbie's data; when I see a newbie who is posting data that I find indicates a real possibility of pressure induced CAs, I'll tell them that. But I also try to also reassure newbies who are likely dealing with machine scored CAs scored during sleep transition and SWJ periods that focusing on comfort and getting a good night's sleep with the machine may do more to fix the "CA problem" than doing lots of tweaking to the clinical settings. And EPR is NOT a clinical setting. Yes, it can have some implications for some PAPers, but most PAPers who like and use EPR don't have any problems with it compromising their therapy or their sleep quality.

I am glad that you got brave enough to turn EPR up to 3. I'm even more glad that you got a decent night's sleep with EPR = 3. Hopefully it's the first of many good nights for you.
Questions about SleepyHead?
See my Guide to SleepyHead
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