Talk about it and spread the word to others that this is impossible to do.
There's also some interesting discussion here, mostly to the tune of "it won't work":
http://www.eevblog.com/forum/crowd-funded-projects/the-airin...
I was hoping that someone in this community would know someone in indegogo responsible enough to say wait a minute, this is not plausible. I took a look at indegogo's terms of service and found only this:
"If the Campaign is claiming to do the impossible or it's just plain phony, don't post it. "
Which is pretty weak.
But I suppose the old saw that 'a fool and his money are soon parted' still applies in the crowdfunding world...
And here's a -real- battery powered CPAP machine, taking a laptop-type lithium ion battery:
http://www.cpap.com/productpage/Hoffman-Laboratories-Breathe...