Why are my numbers so much higher with a FFM?

[MoodyMolly]

I usually use nasal pillows, but the other night I had a stuffy nose and had to use my backup FFM (Simplus). Halfway through the night my nose unplugged enough to switch back to the pillows. But my AHI for the first half of the night with FFM was annoyingly high at 17(possibly 24, depending on when I actually switched to the pillows.) Apparently with my allergies and how often I get colds, my nose will be plugged enough to have to use a FFM from time to time, so I'd like to figure out how to get my numbers down while wearing it. Does anyone have any suggestions on what could be going on, or what changes I could make?
These are my results for that night, first half is FFM, and at some point I switched to the pillows:
https://imgur.com/a/Rz04k

[nicholasjh1]

I honestly think that nasal interface masks may be more efficient at removing apneas... or the same pressure with a nasal interface is higher that with a FFM. for instance, I moved to a nasal from a full face... the full face needed 16 CM of pressure to keep my apnea's low... when I put on the nasal that felt like a much higher pressure... I had to lower my minimum to 12.2 and I'm still getting a similar low number of apneas.

The other thing that could have been happening, is that at least for me when I have a stuff nose and esp. Inflammation that can raise my AHI. so the combo FFM vs Nasal pressures and the cold could have drastically raised your AHI.

[Matt00926]

FFM can require more pressure for the same therapeutic outcome as nasal pillows or nasal masks.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4990949/

[Pugsy]

Looks like you needed more pressure but the machine couldn't go higher. It maxed out at 15.
Now it is possible that the congestion was to blame for it wanting/needing more pressure but it also might simply be that with a full face mask (and congestion not a factor) you need more pressure to hold the airway open and prevent the collapse of the airway in the first place.
Usually it's the minimum but in your case might also be the max since you are limiting the max to 15.

For some people they just need more pressure with a full face mask than they need with a nasal interface mask. Not sure why unless it is related to the position that the full face mask ends up causing to the face and the airway. Seems like they will sometimes pull that lower jaw backwards a bit and that can cause narrowing of the airway and make it even more difficult for the airway pressure to hold the tissues open.

I know one guy who needed 17 cm minimum pressure with a full face mask to get decent reports and was able to reduce that minimum to 13 when he changed to nasal pillows....to get the same decent reports. I had to nearly twist his arm off to at least try a nasal pillow mask..needless to say he was a happy camper.

So in your case...the congestion itself could be driving the pressure and the cause of the flagging...I don't know for sure if the pressure had been allowed to go higher if the AHI would have reduced or not. If the machine is flagging nasal congestion as apnea events...more pressure might not help.
Meaning I don't know for sure if those flagged events are airway related or nasal mucosa (inside your nostrils) related.

[MoodyMolly]

That makes sense, that the flags could be the resistance of mucous and not obstructed airways. Also, needing more pressure with a FFM than pillows makes sense as well. I think I'll try the FFM again with a clear nose and see if that makes a difference, and then try a higher setting if it doesn't. That way I can use it when my nose is blocked, and still get a good night.

[Pugsy]

Good plan...try the FFM when nose is normal and then you will have a better idea about pressure needs and potential cause of those events you saw flagged.

[Bons]

No suggestions, but wanted to let you know you are not alone. My pressures and AHI are much lower when I use a nasal mask than when I use a full face. Unfortunately I need the full face during winter months due to chronic sinus issues.

[ShinRyoku]

I usually use nasal pillows, but the other night I had a stuffy nose and had to use my backup FFM (Simplus). Halfway through the night my nose unplugged enough to switch back to the pillows. But my AHI for the first half of the night with FFM was annoyingly high at 17(possibly 24, depending on when I actually switched to the pillows.) Apparently with my allergies and how often I get colds, my nose will be plugged enough to have to use a FFM from time to time, so I'd like to figure out how to get my numbers down while wearing it. Does anyone have any suggestions on what could be going on, or what changes I could make?
These are my results for that night, first half is FFM, and at some point I switched to the pillows:
https://imgur.com/a/Rz04k

As others have mentioned, some people have lower AHI with nasal or nasal pillows than full face mask. A couple recent studies have looked at this:

https://www.ncbi.nlm.nih.gov/pubmed/27448430

https://www.ncbi.nlm.nih.gov/pubmed/27306398

The reasons for this are not fully understood but likely involve one or more of the following depending on the particular person and particular mask:
-Greater neck flexion with full face mask
-Lower jaw being pushed backwards with full face mask
-More mouth opening with full face mask

One thing that may help is wearing a soft cervical collar, which can address all three of the above issues - neck flexion, jaw position, and mouth opening:

http://jcsm.aasm.org/ViewAbstract.aspx?pid=31144

[TedVPAP]

Slightly off topic but make sure you give your pillows a chance to work even when congested. Even when blocked, I have always been able to get the air path open and keep it open all night. Take the mask off in the morning and the congestion takes over again. Eight years using pillows. My min pressure is 16 so that likely helps open up the path.