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Wondering1 wrote: ↑

Sat Aug 26, 2023 9:39 pm

lazarus wrote: ↑

Fri Aug 25, 2023 8:56 am

The technician is right that CPAP/APAP is primarily aimed at treating AHI.

Better: The technician is right that CPAP/APAP is primarily aimed at treating Obstructive apneas and flow limitations, not at all for clear airway apneas.

No. That would be very wrong, since CPAP often solves ALL forms of apneas, given time, and is often aimed at centrals:

viewtopic/t187112/Interesting-discussio ... SA---.html

Yes that is indeed a very interesting discussion. I'm going to get the sleep report and take it from there. I have my suspicions but am not leaping to conclusions yet.

ozij wrote: ↑

Sun Aug 27, 2023 12:12 am

I wonder if the fact that CPAP is not helping can be sufficient grounds for him being give in lab study and titration.

Let's hope so!

lazarus wrote: ↑

Sun Aug 27, 2023 12:17 am

Wondering1 wrote: ↑

Sat Aug 26, 2023 9:39 pm

[ The technician is right that CPAP/APAP is primarily aimed at treating Obstructive apneas and flow limitations, not at all for clear airway apneas.

No. That would be very wrong, since CPAP often solves ALL forms of apneas, given time, and is often aimed at centrals:

What a curious thing to say.

I've not seen my machine respond to clear airway events - have you?

So how do CPAP machines "treat" these types of events?

So Ozij suggested trying to track the relationship between the flow limitations, central apnea and pressure swings. Does this reveal anything? I'm a bit lost at this point.

https://imgur.io/a/vsCVYvb

wobblycrayon wrote: ↑

Sun Aug 27, 2023 6:53 am

So Ozij suggested trying to track the relationship between the flow limitations, central apnea and pressure swings. Does this reveal anything? I'm a bit lost at this point.

https://imgur.io/a/vsCVYvb

What I can tell you is that (in my OSCAR) graphs:
If there is no change in flow limitations, the CPAP DOES NOT change pressure during or immediately after a clear airway event.

AS I understand it, flow limitations are a suggestion that that the airway is undergoing a changing dynamic that may eventually lead to a full obstruction. If the machine is "seeing" or "sensing" that a full obstruction is on the way, it is understandable that the method to combat that is to increase the pressure (splinting the airway).

In the case of a clear airway, there is no obstruction, ergo, the machine will not increase (or decrease) pressure(splinting) as there is nothing to be accomplished.

wobblycrayon wrote: ↑

Sun Aug 27, 2023 6:53 am

So Ozij suggested trying to track the relationship between the flow limitations, central apnea and pressure swings. Does this reveal anything? I'm a bit lost at this point.

https://imgur.io/a/vsCVYvb

My suggestion refers to the chart for the whole night, not when you focus on the apneas for short periods.

Ok thnx I will have a look at that this evening.

Look at a number of nights:
Do they all have those pressure swings?
Does it seem like flow limitation occur just befoe the pressure zooms?
Are there more central apneas in those pressure changing times (when pressure goes up or down)?

ozij wrote: ↑

Sun Aug 27, 2023 10:13 am

Does it seem like flow limitation occur just befoe the pressure zooms?

It should because flow limitation grade (0-1.0) will initiate a pressure increase (by design)

Are there more central apneas in those pressure changing times (when pressure goes up or down)?

SO, can the clear airway events be minimized by using constant pressure (as opposed to varying pressure)?
Useful question.

So I have had a look at the pattern of flow limitations, pressure change and apneas over a few days (as suggested). A flow limitation invariably leads to a rise in pressure. But that does not always coincide with an apnea. Sometimes it does. But there are many apneas appearing where there does not seem to be anything happening re flow limitations or pressure changes.

wobblycrayon wrote: ↑

Mon Aug 28, 2023 3:56 am

So I have had a look at the pattern of flow limitations, pressure change and apneas over a few days (as suggested). A flow limitation invariably leads to a rise in pressure.

That is to be expected.

But that does not always coincide with an apnea. Sometimes it does. But there are many apneas appearing where there does not seem to be anything happening re flow limitations or pressure changes.

You are referring to central apneas.
And if I understand you correctly, you don't see more cental apneas when the pressure changes.
Modern auto algorithms do distinguish cental apneas from obstructive ones and do not raise (or lower) pressure in response to central apneas.
However, if a person is aroused from sleep by flow limitations or pressure changes, there may be more "post arousal" cental apneas in their breathing.

A flow limitation means that the inhale pressure is too low - and by being given the leeway to go too low, the machine is actually playing catchup with the tendency of your son's airway to collapse. Things stabilize, and down the pressure goes, letting the disturbances appear again.

We don't know how the central apneas are related to that pattern, but we do know that as a general rule, EPR in lower pressures may be conducive to central apneas.

Thanks for this Ozij.

So if i have understood you correctly, all (or most) of these central apneas could basically be a bit of an artefact? That is, response to arousals? Just a bit of a delay before the centrals start appearing.
So by and large he is being undertreated at too low pressures and EPR is not helping? Is that a fair assessment of your thoughts ? It would certainly be rather reassuring if this is what is going on. (Still don't have the sleep study, public holiday here).

wobblycrayon wrote: ↑

Mon Aug 28, 2023 8:32 am

Thanks for this Ozij.
[...]
So by and large he is being undertreated at too low pressures and EPR is not helping? Is that a fair assessment of your thoughts ? It would certainly be rather reassuring if this is what is going on. (Still don't have the sleep study, public holiday here).

I find it easier to respond the above. Yes, I think its probable that he is being undertreated at too low pressure and EPR is not helping.

As for the CA's:

wobblycrayon wrote: ↑

Mon Aug 28, 2023 8:32 am

So if i have understood you correctly, all (or most) of these central apneas could basically be a bit of an artefact?

They could be. But we don't know, and could doesn't mean "are".

And since it was a home study, a major question is "was it capable of distinguishing central apneas from obstructive ones"?
It will also be interesting to see if he has more obstructive events during REM sleep.

In recent years, the process of identifying sleep disorders and finding the correct way to treat them has moved to:

• Home study
• Automatic machine set wide open to titrate the correct pressure
• (hopefully) adjustment of machine settings based on results.
  or
• lab study if the machine can't be set to help the person get good results.

That's when things are working as they should. However, some professionals (or rather "professionals") behave as though they believe an automatic machine can be left to its own devices without further settings.
Treatment of sleep-disordered breathing with positive airway pressure devices: technology update

In our experience, many patients left on AutoCPAP 4–20 are undertreated and may present with awakenings a couple hours into sleep, residual symptoms, or difficulty tolerating PAP. Some patients are sensitive to the pressure changes, so if patients are not doing well with AutoCPAP, fixed CPAP should be tried.

As you can understand from the quote, "undertreated" because the minimum is left at 4, not because the machine is given its head to go to the maximum.

Got it, thnx.