[CPAP] OSCAR confusing me with leaks/apneas

[kappa]

If you look at the image in Post #6. You will see that, the excess leaks, are always  13/L MIN below the total pressure.

Doesn't change with pressure. 

Which is not how it's supposed to act, I figured? As you said, it's supposed to subtract expected leaks on the scale as put in preferences, based on pressure.
I just assumed the software gets confused and defaults to 13 as some sort of default number.

  
If I re-import everything, it resolves itself, but otherwise it defaults to this 13 L/min expected leak.
I don't know how else to explain it, it just seems to be a software malfunction. I don't have the problem on SleepyHead 1.1.0

Yes, I see the 13 difference here, but in other screenshots you have a difference of 30. So it's not clear what the exact history of settings and imports is.

As I have stated before, the leak values are calculated on data import, so changing the preference values later does not impact old leak values, only new or reimported ones. Happy to try and fix this in the code if we see a reproducable problem... as I suggested before, post details in the software support forum. I've looked through the code and can't see why you would get an intentional leak of 13 (particularly if your leak value preferences were 20-49).

Flat tops of inhales are associated with flow limitations (i.e. airway restrictions of some sort). Flat periods between breaths (as long as they aren't too long) shouldn't really be cause for concern.

[godletmesleep]

If you look at the image in Post #6. You will see that, the excess leaks, are always  13/L MIN below the total pressure.

Doesn't change with pressure. 

Which is not how it's supposed to act, I figured? As you said, it's supposed to subtract expected leaks on the scale as put in preferences, based on pressure.
I just assumed the software gets confused and defaults to 13 as some sort of default number.

  
If I re-import everything, it resolves itself, but otherwise it defaults to this 13 L/min expected leak.
I don't know how else to explain it, it just seems to be a software malfunction. I don't have the problem on SleepyHead 1.1.0

Yes, I see the 13 difference here, but in other screenshots you have a difference of 30. So it's not clear what the exact history of settings and imports is.

As I have stated before, the leak values are calculated on data import, so changing the preference values later does not impact old leak values, only new or reimported ones. Happy to try and fix this in the code if we see a reproducable problem... as I suggested before, post details in the software support forum. I've looked through the code and can't see why you would get an intentional leak of 13 (particularly if your leak value preferences were 20-49).

Flat tops of inhales are associated with flow limitations (i.e. airway restrictions of some sort). Flat periods between breaths (as long as they aren't too long) shouldn't really be cause for concern.

It's not really a concern for me, leak rate line is kind of useless retrospectively.

Flat tops of inhales are associated with flow limitations (i.e. airway restrictions of some sort). Flat periods between breaths (as long as they aren't too long) shouldn't really be cause for concern.

There are some forum posts associating flat tops with mouth-breathing, some by those on this thread.

1. http://www.apneaboard.com/forums/Thread-Mouth-Leak-vs-mask-leak 
   
2. http://www.apneaboard.com/forums/Thread-CPAP-How-does-the-Flow-Rate-graph-look-like-if-you-are-nose-breathing-only
   

There used to be discussion that the flow-rate was not important in considering mouth leaks, but for whatever reason it seems that argument has shifted.

Not quite sure what else would cause such dramatic drops and such a flat flow curve. I mean flow limitation is possible, but so far no pressure adjustments have fixed that and the flat tops are even more pronounced during plateau leaks.

There's a flow limitation for flat tops, but those are anything but minor, as they indicate complete upper airway collapse.

[kappa]

Flat tops of inhales are associated with flow limitations (i.e. airway restrictions of some sort). Flat periods
between breaths (as long as they aren't too long) shouldn't really be cause for concern.

There are some forum posts associating flat tops with mouth-breathing, some by those on this thread.

1. http://www.apneaboard.com/forums/Thread-Mouth-Leak-vs-mask-leak 
   
2. http://www.apneaboard.com/forums/Thread-CPAP-How-does-the-Flow-Rate-graph-look-like-if-you-are-nose-breathing-only
   

There used to be discussion that the flow-rate was not important in considering mouth leaks, but for whatever reason it seems that argument has shifted.

Not quite sure what else would cause such dramatic drops and such a flat flow curve. I mean flow limitation is possible, but so far no pressure adjustments have fixed that and the flat tops are even more pronounced during plateau leaks.

There's a flow limitation for flat tops, but those are anything but minor, as they indicate complete upper airway collapse.

mulitcast's example of mouth exhale below (from this post) has a flat base, which is below zero because the PAP assumes that avg inhale volume == avg exhale volume, so even if all exhale is going via the mouth the machine will invent an "exhale" period (which in reality is a "zero" flow period). (The first part of the image is mouth inhale/exhale with the mouth exhale only on the right).

   
This is from an Airsense 10 so it reports unintentional leaks rather than the total leaks you are seeing from the Dreamstation.

I don't think the other examples there are indictive of assymetric breathing. IMO the flat period between breaths (if it exists) being on zero is indicative of symmetric breathing.

A flat top is not indicative of complete airway collapse, since that would have zero flow and be marked as OA (if long enough). Could be some form of UARS though, which wouldn't necessarily respond to additional pressure.

[multicast]

Please keep in mind that the zero line is always only *estimated* -- which makes the oracularities even harder.

[kappa]

PAP machines generally only have an air pump, a (total) flow sensor and a pressure sensor (and some other incidental compute and interface components . My interpreation is that Total leak = (rolling) average (total) flow. "Flow" (as reported by OSCAR) = (total) flow (instantaneous) - total leak (current rolling average). As such, yes, the zero line is an estimate based on the rolling average flow but the volume above the zero line should be similar to that above the line (i.e. what goes in must come out). Asymmetric leaks mess things up, but for most the zero line is fairly accurate regarding air flow in/out of the body.

[godletmesleep]

A flat top is not indicative of complete airway collapse, since that would have zero flow and be marked as OA (if long enough). Could be some form of UARS though, which wouldn't necessarily respond to additional pressure.

A flat top is indicative of "collapse of non-compliant upper airway" as seen in Class 7 on Dr. Guilleminault's research alongside others in evaluating flow limitations.


The erratic nature leads me to believe that a flat top like this isn't necessarily a flow limitation. As I am more than willing to try an occam's razor approach before acting on what could be a more complicated problem.  If the mouth leaks aren't the cause, I'm welcome to hear your suggestions for a solution as to why my night is riddled with all these top plateaus. It could be a mix of both, I don't know, but I don't see a point in debating anything here.

I'll yield to the point that I have some flat tops going on while awake as well, so that could be indicative of a problem. But if its a flow limitation, a pressure increase has failed to redress it completely if at all.

Attempting a firmer taping last night, actually gave me my lowest AHI yet, at 1.63, and my lowest user flags yet, at 1.90. 
So clearly it did something, sure, I am still tired as I am still awoken constantly. (I need to evict my cat from my room... he's been bothering me a lot lately.)
Also, I still had mouth leaks on my leak graph as I woke up to find the tape seal once again broken. 

A full face mask might be what's needed for me to be honest.

I just want a good nights sleep where I don't have 30+ awakenings... because thats my current reality.

[kappa]

The language in that table is a little confusing - easy to interpret 'collapse' as meaning 'complete collapse' - but I think the intent is just to mean that there is an upper airway restriction. The entire paper is here and is worth a read if you haven't already.

A full face mask may work here, particularly if you have nasal restrictions. You mention that you were initially diagnosed with UARS, have a deviated septum?, RLS, (possibly) PLM, ...

If there are multiple contributing factors, simply applying air pressure up your nose may not be sufficient to improve your sleep. I certainly wish it was enough for me...

Improving sleep hygene by evicting the cat, and any other simple measures you can take, sounds like a great idea.

[sheepless]

"I just want a good nights sleep where I don't have 30+ awakenings... because thats my current reality."

I agree w kappa.

at risk of sounding like the proverbial broken record, imo, you are likely to continue to have this problem until you sort issues external to pap, especially the movement issue.