[CPAP] Analyzing inspiration data

[tkblizard]

Hi all,

I had a few quick questions about inhalation/exhalation shapes and what they mean.  My breathing shape/pattern doesn't seem to really fit any of the ones I saw in the (awesome) guide, and in trying to sort out what is happening in the peaks, valleys, and plateaus. 

As to the shape of things, mostly I am curious why there is a flat shoulder of sorts on my breathing peak and what that means is happening at that point morphologically?  Is the flat shoulder a pause before I inhale or am I trying to inhale and there is resistance?  Is it worrisome at all and does the EPR help or make this breathing pattern worse?  Maybe I just pause a bit naturally between breaths?  It looks a bit like an extreme class six inspiration shapes but what are the jagged bits and why the sharp drop before?

Here are few screen shots.  Many of my apneas seem to occur after a big inhalation or maybe movement so I never know whether to mentally count those as true apneas - and did I really not breath for 36 seconds?! Thanks!

   
   
   

[PeterFD]

Your sleeping air flow rate looks much like mine. In my breathing, what you call a "shoulder", is the tail of the exhale phase. After the peak exhalation rate, the rate seems to decrease exponentially (sort of) until it reaches zero for the start of inhalation. When I am awake this portion is more rounded and curved the other way and in between the two this portion can be almost a straight diagonal line.

So far as the inhalation phase is concerned, mine seems a bit more ragged but not too different.

That doesn't mean of course that you and I are both normal. 

I notice that your mask pressure wave is a little different to mine, probably because your machine is a later model. With mine, while breathing out or not breathing, the pressure is minimum (i.e. set pressure minus EPR). At the start of inhalation, the pressure slowly ramps up to the maximum (the set pressure), reaching it at about the end of the inhalation phase, when the pressure drops abruptly to the minimum again. With your machine at the end of inhalation, the pressure drops more or less exponentially. A different applied air pressure must have some effect on the shape of your air flow rate.

[jdougc]

There seems to be some disagreement with this type of flow limitation. 
Many see the rounded top and say it looks great, but I don't think so.

If all of that is above the zero, then that is the main concern. 
Your step/delay in the inhalation doesn't seem to be above the zero level though, so it is not considered a flow limitation.

It looks very similar 6 flow limitation. but that inhalation delay would have to be above the zero level. It may be a slow exhalation or what PeterFD called "the tail of the exhale phase".

   

I will let more experience people weigh in.

[tkblizard]

Thanks for the insights PeterFD, and glad I have company.  I've had this same pattern with several different mask types (full, pillows, Bleep) and different pressure and EPR settings.  I've never turned EPR off entirely to see what might happen (a bit chicken because finally gotten consistent low AHI).  But like many others, I still can sometimes but not always wake up quite tired.  Every night is an adventure!

Thanks also jdougc - I hadn't really thought about where the plateau was with respect to the zero line. Maybe my sleep breathing is driven more by CO2 buildup and I just don't inhale as often leading to extended exhale periods.

[WisNaeMe]

You'd be better off looking at a one-minute zoom of your flow charts, rather than the 5 minutes you've selected - in 5-minute zooms, breaths tend to look very elongated and distorted.

A one-minute view will look less exaggerated and any flow limitations you might have will then more mirror the shapes described in the flow limitation class chart.

You should then find that what you describe as the 'shoulder', is just the end of a normal exhalation (i.e. below zero).

The CA prior to the OA may just be treatment emergent (TECSA) or simply breath-holding after a positional change.

But the statistics panel suggests that your machine is picking up very few FLs at EPR=3 (the setting you are using). Reducing EPR a bit might help reduce CAs, if these have or start to become persistent. But all-in-all you're not having a lot of events (if this night is typical).