Normal for exhale peaks to be much greater than inhale peaks?

[stony82]

Hi, I'm new to my CPAP journey, only a couple of weeks in and still figuring out a lot of things.

One thing I regularly see in my flowrate graph is that the size of my exhales is much greater than the size of my inhales - often two or even three times greater.  In this screenshot my inhales are around 15, and my exhales are -30 to -50.

I've seen a few OSCAR flow rate charts on this forum and on YouTube, and haven't seen any that have the same pattern.  And I'm confused how I could be exhaling so much more than I'm inhaling.

Is this normal?  Anyone know what could be accounting for it, and whether it needs addressing?

OSCAR screenshot attached.

[Gideon]

Welcome to the forum.
That part is not abnormal, your inhale dipping into a brief exhale is a bit abnormal.

The biggest issue is you have a positional apnea issue starting at 00:30, see how your obstructive events are clustered together, that's the tell.
I suggest you set your min to 8 (Dreamstations benefit from having pressure set to near where they want to run and you should run Flex at 2 (this need min set to 6 for full use to be available)

On the positional issue, most likely this is from you tucking your chin which often crimps your airway, much like kinking a garden hose. This 1 vs 2 pillows, softer/less firm pillows to keep your neck straighter. If that doesn't work you may need a soft cervical collar to help (see my signature)

[stony82]

Thanks for your reply and the welcome!

And thanks for pointing out the positional apnea.  I didn't want to throw too much info into my first post, but it's something I realised too a few days ago (partly due to the advice on the excellent wiki), and I can recreate it easily even during the day just by tucking my chin down a little bit.  It barely has to be below a right angle to cause issues.  I've made an appointment with an ENT, and have been trying to solve it at night with the sorts of mechanical aids you suggest.  I have a cervical collar, which does help but is too uncomfortable to wear, and more on the way that will hopefully be softer.  

Per your suggestion I tried a lower pillow last night but was unable to get to sleep with the mask on - still getting used to everything - so I'm not certain yet if it helped.  I will try the suggested pressure settings too, but general nasal breathing difficulties (also planning to ask the ENT about) make it hard for me to exhale at higher pressures, so I usually max out CFlex.


> That part is not abnormal, your inhale dipping into a brief exhale is a bit abnormal.

Ah ok, thanks for the tip.  I went back through previous data and this dipping doesn't seem to happen on any other night.  So it was probably a side effect of this night's experiment, which was lying on my back without a pillow.  (I know that's not meant to be great for apnea, but I found while awake that it really 'unkinked the hose' and was curious if it would help at night.)  So, probably fine for me to ignore this one unless I see it again.

[quiescence at last]

In the section posted, your breathing is not labored, and exhibits a calm sleep. I would not be concerned if I had that happen routinely. The amount of volume inhaled is very near equal to the amount exhaled. you just inhaled less for a longer period of time.

QAL

[stony82]

Thank you QAL, that makes sense.  I'm very new to this and still figuring out what's weird or normal in the data, particularly when I see patterns I haven't seen in anyone else's graph, so it's reassuring to hear from the experts on here that this one's nothing to worry about.  Plenty of other mysteries to figure out still, but I'll quit worrying about this one.