Expiratory mouth breathing?

[Barefooter64]

My wife has some flow rate structures that I don't understand.  The flow rate graph has sections that are flat bottomed compared to other times.  The attached image is a 30 second section of one of those times.  The Optimizing Therapy wiki article has an example of something called expiratory mouth breathing that seems to match this.  She tapes her mouth so can this happen with expiration through her nose?

During this time the leak rate was around 2.4 and dropped to 1.2 at the mid point.  Similar flow rate structure happened a few days ago during a time when there was no leaking.

[G. Szabo]

It looks like a palatal prolapse. Mouth taping makes it more obvious.
The best nonsurgical resolution is nasal stent. See for example 
Alaxo Hybrid Stent with CPAP - Therapy Thread ( 1 2 3 4 )

[Barefooter64]

Thanks.  Very plausible as she has connective tissue disorder.

Some medical discussions of this mention that it typically doesn't cause desaturation.  It doesn't seem to be causing arousals.

[G. Szabo]

I have a first-hand experience with this palatal prolapse (PP) condition. 
Indeed, it does not significantly reduce saturation. However, the inhalation peaks are reduced during this period because you cannot fully exhale the inhaled air. This causes sleep disturbances. I feel groggy when it lasts a long time at night. Also, I often wake up during or after these PP periods. This is why different surgical interventions are used. 

In addition to the link I provided above, she might want to try positional therapy, which worked for me.
[Treatment] Palatal prolapse mitigated with positional therapy.

You can also find some threads on the stents
Alaxo 6" St"nt - Treating Soft Palate Obstruction

[How to] Homemade improvement of the Alaxo Hybrid Stent, i.e., the 5" lo"g.

[Product Review] AlaxoStent Review (6” FD" Approved) ( 1 2 3 4 ... 7 )

Alaxo 6" St"nt - Treating Soft Palate Obstruction