On their website AA clearly states that passengers are allowed to bring one bag plus one personal item. CPAP machines are cited as an example of an "assistive device" that can be carried on board "above and beyond the restrictions" of the one bag and one personal item.
Of course they also say:
-At some airports, carry-on baggage may be more restricted.
-Additional limits may be placed on carry-on bags because of aircraft stowage capacity.
-Limits may be imposed after the boarding process has begun.
So, it would appear from their website that consolidating your CPAP into one of the two allowable carry on items is above and beyond what one should need to do, however any planning for any type of carry on is subject to being completely blown out of the water at the gate or on the plane. It probably will be blown out of the water these days with the nutty checked bag policies.
Can someone get through to the airlines that increased seating and charges for checked bags should necessitate planning for a way to deal with the resulting increased carry-on luggage. A decent gate-check system or first bag checked included in ticket price would go a long way.
Heck, if they are desperate for baggage income allow a free checked bag and a free personal item carry-on - charge me for my roller carry-on. I would be paying extra for the convenience of not waiting for unloading and for using precious cabin space. There might even be room left in the cabin for our CPAPs to be carried hassle free.