Jenna-
I know it seems strange that a highly technical BiPAP ST can run on alternative power sources, but a simple heated humidfier can't, but AA is correct that the planes power source will not work. It has to do with the type of power a heated humidfier uses that makes them malfunction when not using a regular plug in and damage the humidifier. I don't know the technicalities, other then it needs a pure Sine (sp?) wave power, which battery packs & other alternative power sources can't provide. Which brand of BiPAP does Elizabeth have? Most Repironics can be run on DC power with the correct cable, which is a lot more efficient if you are using a battery backup type system. When you convert battery power to DC power through an inverter, you waste a lot of power in the conversion- and BiPAP use more power then regular CPAPS, so we need to conserve all we can (Respironics Synchrony BiPAP ST user). You can use the humidfier as a passover, possibly having a flight attendant warm distilled water every so often in the planes galley so she gets more moisture then from cold water. If you insulate the humidfier with a blanket or something, it would keep the water warm longer too.
I noticed on her site you had problems with her enteral feeding pump on a recent trip- I'm glad they got it straightened out & you were able to fly with next day. As an adult who uses an enteral pump, I would be interested in what the other name they finally found it under. I don't have any plans to fly anywhere soon, but I would like to be prepared, just in case. Also, which brand of enteral pump does she have? The best thing I did was switch DME's so I could get a Zevex Enterlite instead of a Kangaroo Pet, as the Enterlite is so much smaller, lighter, and not fussy about how its positioned. Zevex even has a newer, smaller pump out now called the Infinity.
Here is a link to a thread at another site that has links to most of the discussions on using batteries for xPAPs from several Apnea/xPAP forums-
http://www.cpaptalk.com/viewtopic.php?t=9682 Alot of them are camping related, but its the same issue of how to use alternative power sources for xPAPs.