I have been on my bipap for almost 30 years. The g irst time we lost power I went out and got a a small APC UPS. it will run my m-series for almost 8 hours without the humidifier. They only run 30 to 40 so really worth it for peace of mind....
Ps: if you get one be sure to disable the alarm. I havevslep thru msny outages and never even noticed til i had to reset the clocks the next day.