Resmed Quattro Sizing Guide comes to the rescue?

I have made several attempts in the past to use a medium sized, full face mask (Quattro FX) but none were successful. The other day, I happened upon a sizing chart for the Resmed Quattro. To my great surprise, the recommended measurement indicated I needed a small! This was surprising because I normally use a medium in everything, doesn't matter what it is. So, I decided to take an expensive gamble ($125) and ordered a size small Quattro and darned if it didn't seal well and there was no fluttering.

The test was not perfect however, because after about 4 hours, I woke up with dry mouth, so I upped the humidity level from 4 to 5. I woke up probably 5 or 6 more times with itching nose and/or itching skin. I definitely didn't get a great sleep but I'm thinking that it may be just be that I need to get used to the new mask.

MyAir.Resmed.com indicated that I had a good seal but what is a bit confusing is that my AHI was 5.1, versus the 1 or less I get with a Zest Nasal mask with mouth tape. Does anyone how I can have a good seal but increased AHI?

For everyone's reference, here is the Resmed Quattro sizing guide:

https://cdn.shopify.com/s/files/1/0783/ ... guide.webp

SligoReef wrote: ↑

Wed Apr 08, 2026 11:43 am

what is a bit confusing is that my AHI was 5.1, versus the 1 or less I get with a Zest Nasal mask with mouth tape. Does anyone how I can have a good seal but increased AHI?

It's fairly common for people who go to a full face mask from a nasal mask that they end up needing a higher pressure with the full face mask if the increase in apnea events are from obstructive or hyponea events.

Which event category did you see the increase?
Perhaps you just need a higher baseline pressure to better prevent obstructive/hyponea events.

Pugsy wrote: ↑

Wed Apr 08, 2026 11:58 am

SligoReef wrote: ↑

Wed Apr 08, 2026 11:43 am

what is a bit confusing is that my AHI was 5.1, versus the 1 or less I get with a Zest Nasal mask with mouth tape. Does anyone how I can have a good seal but increased AHI?

It's fairly common for people who go to a full face mask from a nasal mask that they end up needing a higher pressure with the full face mask if the increase in apnea events are from obstructive or hyponea events.

Which event category did you see the increase?
Perhaps you just need a higher baseline pressure to better prevent obstructive/hyponea events.

Unsure what is meant by category. My machine and myair.com only mention "events" which I assume is the same as AHI.

category of events that compose up the AHI

Obstructive Apnea

Central Apnea

Hyponea