I found this on the web. ResMed states that the 115 volt 400 hz power supplied on aircraft is compatible with their machines.
Note that this is from ResMed and only applies to their machines.
Note also that this does not discuss whether airlines will let you use this power for a CPAP or whether there will be a power outlet at any given seat.
Link ===> https://www.resmed.com.au/knowledge-hub ... e-aircraft