Here is another option.
http://omronhealthcare.com/product/1136-201-respiratory-devices-compact-compressor-nebulizer-ne-c30
 This unit will run on 12vdc if needed.
If you check out the link http://www.fugitt.com/cs_notes  and go to 
testimonials, there is an interesting document.
Thank you Gail, for bringing it to my attention.
mike