Ninja, I know you are totally supporting his wishes. I meant that if he doesn't want an ICU stay, you would be his advocate in that respect as well.
But you say you tried and it didn't work out, and I don't know anything about how things work in Vancouver. I guess it's late in the game, but for others who might read this in future, secondwindcpap does ship BiPAPs internationally, if you get an rx from any doc -- doesn't have to be your neuro.
So I guess you go back to him and he has that choice. [edit: our posts crossed, so he took a right turn, very understandable]. As Nikki says, if there is an underlying cause for the O2 drop, perhaps they will find it there [or further outpatient testing will reveal it]. And it is true that there are several treatable possibilities.
Decompensation is where the person with ALS takes in so little air over a period of time that their lungs lose the ability to hold it and biochemically do the exchange of CO2 and O2 even if a machine pushes it, often with pneumonia and/or lung collapse. So, there is a set point where if someone waits too long to do BiPAP, it may not work well. From what you say, though, that may not be the case with your husband at all.
Keep us posted -- anything we can do.
Best,
Laurie