Here is the promised update. First, thank you, once again, to JDS74 for donating the materials.
To recap, my main problem with the Fisher & Paykel Oracle 452 is that it makes me keep my mouth open, without the possibility to close it temporarily (e.g., to swallow or redistribute saliva), and on top of everything, it props the mouth wide open by pushing the incisor teeth apart. This not only has the potential to displace one's incisors but to allow the jaw to slide the wrong way (could be backward, forward or even sideways), thus causing TMJ pain. I had already dealt with that and the only thing that helped keep my jaw in check was a mouth guard together with a DIY chin strap.
So, I decided to make some modifications to address the above problem and here is the first iteration. I tried it for one night and it wasn't a great success but it certainly was a step forward. The goal here was to remove the part of the mask's mouthpiece that protrudes inside the jaw (behind the teeth line). The Oracle has this rigid base to which an inner soft piece attaches and an outer soft piece is screwed on to keep a tight seal on the lips.
First, I used a coping saw to cut the portion that enters the mouth and then used a rotary tool with a cutter bit to shape it and smooth it out. Here is the result, side-by-side with the unmodified piece:
Notice how the squid-tale shaped pieces are intact, because that is where the soft piece attaches. The latter has a protrusion that goes over the part that I cut out from the rigid piece, so I also cut that portion of it with a pair of small, round-tipped cosmetic scissors:
And here is the same thing as seen from above:
Again, I took special care to avoid cutting into the opening for the squid-tale shaped tabs. When assembled the whole thing looks like this:
... also, a view from above:
... and one more view:
Now, it is probably natural for most to keep the mouth open to breathe but I thought I'd give it a little incentive and also, since I normally use a mouth guard to keep my jaw in check, hope to achieve the same in this situation, so I made a mouth guard in such way that 1) the teeth will rest on it in the back (the strong molars) and 2) by cutting the portion in front of the incisors, I left room for air to enter the mouth:
... and from below:
This is made from regular silicone dental trays, usually sold for tooth-whitening purposes, and are very cheap ($5 for a four-pack at Amazon:
http://www.amazon.com/gp/product/B003UP ... UTF8&psc=1). I use hot water (dip quick lest it melts into a blob) and shape with my mouth and fingers. Then, I cut out the front portion, leaving enough to keep the two sides together.
Ideally, this would be part of the mask mouthpiece so it doesn't move around, like this:
With this modification, I can still close my mouth if I need to swallow or swish around the saliva, but the mouth normally stays just open enough to be able to breathe. I set my pressure to min EPAP of 9 cm H20 and pressure support of 5 cm, and still had several obstructive apneas recorded that night (the longest at 30 seconds), but I'm still far from comfortable with it. Even though my nose started out dry when I went to bed, a few hours into the night mucous started blowing through the nose plugs. I have some clips on order, which should address that problem but it seems like the back-pressure promotes the production of mucous because I never have that much. There was also some leaks in the beginning, experienced as "bubbling" in the mouth, between the lips and mouthpiece, but that somehow went away later in the night. That right there tells you that I kept waking up quite often through the night and ended up sleeping no more than 6 hours, but I did catch some dreams, so I definitely had an REM phase. When I woke up there was some minor jaw discomfort, which is not clear whether with longer sleep, several nights in a row, might accumulate to become TMJ pain. I also have a soft cervical collar on order, upon the advice of JDS74, and will see if that would help.
Another issue contributing to the leaks is the fact that I sleep on my stomach and the angle is not optimal. With my nasal mask, I can rest its edge on the pillow/sheets and it will actually support the mask. I have it modified so that the exhaust vent routes the air up above my head. The Oracle's vents are right there and I can't do that (unless I modify it the same way). The problem here is that the Breeze has this arched stem where the hose is routed. With the Oracle, the hose is free to go anywhere it feels like. When I'm on my stomach, with my regular hose support (by the way, the hose of the Oracle is shorter, so I had to deal with that, too), the hose would take various angles and pull the mask, causing leaks. It seems like I may need to find a way to support the hose on my head (same route as the Breeze), which will require something else on my head as the Oracle does not have anything of its own.
There is one other problem that can be overcome but will always be there: the fact that your nose is plugged and the mouth is solidly sealed and you don't have the freedom to do anything other than breathe calmly. This is exacerbated by the actual knowledge of it (psychology!) and, in my case, by my large vital capacity, so if I occasionally need to run a large volume of air, quickly, there is really no way. That night (I'm still not fully recovered from the chest cold) I had to cough in my sleep and I just couldn't inhale or exhale that large amount, so quickly, and I woke up confused and panicked, and could barely recover to remove the strap and the mask, and expectorate the saliva that had entered my trachea. By the way, that strap is necessary in my case - I tried without it but the mouthpiece tends to get blown away, as well as my cheeks stretching from the pressure. Also, the quick-release that seemed to work in the "dry" when I first played with it, isn't so "quick" when you need it.
As far as humidity goes, I left the H5i at 5/6 and the tank lasted the 6 hours but it felt quite dry, albeit, bearable. The H5i is integrated with the S9 such that the tank is fully enclosed by the machine housing, making it very hard to tap for external hoses. It is not so bad as it is, plus it is not impossible to come up with some engineering solution for extending the capacity of the tank, so I don't consider this a major problem.
So far it is not working very well overall but I'm giving it a good effort. When I receive the new nose plugs and collar I'll give it another try and see what is left to make it work. I'll report back here when I have some news.
McSleepy