Higher AHI with new full face mask

[Alimagrog]

I haven’t posted much on this forum, so forgive me if I do it incorrectly.

I have a Philips Respironics DreamStation CPAP and on Friday I got a ResMed AirTouch F20 Full Face Mask to replace the Wisp nasal mask I have been using (because my nose has been randomly getting clogged in the middle of the night so I want to have the ability to breathe through my mouth). Friday night was my first night with the new mask, and my AHI jumped from the typical 1-3 up to 5.8 with an increase in obstructed apneas. My pressure was at 11, so I increased it to 12 last night (Saturday) and my AHI was 5.6 still with a high number of obstructive apneas. Do I need higher pressure because of the full face mask? Do I need to contact my doctor or the medical equipment place about this? I really like the full face mask, but want to use my CPAP correctly.

[Pugsy]

It's fairly common to need more pressure with a full face mask than with what they were using with a nasal mask.
I think it has to do with how the straps on full face masks tend to pull the lower jaw back just a little and causing the airway to narrow a bit. Just makes it a little more difficult to hold the airway open and prevent those collapses from happening.
I know people who have 2 to 4 cm difference in pressure needs between a nasal mask and a full face mask.