I too am bulbar-onset ALS. I was first diagnosed with Sleep Apnea in 1999, but did not start using a CPAP until 2008 when the technology finally had auto-adjusting features available readily. I’ve always used the nose pillows vs. a mask covering mouth.
I was only diagnosed with Bulbar-onset ALS in August 2023 after 9 months of searching for the cause of my slurred speech that showed up after a tongue biopsy in Dec 2022. (Had to run out many things: from stroke to Parkinson’s before arriving at bublar onset ALS.)
Anyway, I’m not sure about the differences between BIPAP and CPAP as I’ve only used CPAP. But, I simply cannot sleep without CPAP.
the Saliva mess I have is somewhat managed with Botox, but it’s very much there. I don’t have the problem with the CPAP machine because the nose pillows force the air down my nasel passageways into my windpipe — with the intention to ‘push’ the tongue out of the way! With Bulbar onset, your tongue becomes a ‘flappy’ mess Which you cannot control much anyway.
I’ve not needed to sleep sitting up. But, I have found a little bit of elevation helps. and, i find that I need to sleep on my side (vs. directly on my back as I have since starting CPAP).
The only usage of CPAP during the day is when I take a nap. I monitor my pulse-ox with a finger device from time to time and constantly via my Apple Watch. Fortunately, I’ve not felt ‘winded’ enough as of yet to push me to use it during the day otherwise.