I too don't understand the reason why CPAP has to be certified for use on aircraft, but that's the line taken by the airlines, possibly due to ignorance. Surely, electromagnetic signature of a laptop, Gameboy, DS or PSP will be different from that of CPAP, ( CPAP might have a peak in a different region of the spectrum), but total energy in the siignature cannot exceed the power drawn by the unit. One difference between a CPAP and other gadgets you mentioned is that some of the energy of those devices goes in display while for a CPAP,. all of the energy goes into driving the motor (pump). Whether peak of the electromagnetic signature of a CPAP lies in an objectionable part of the spectrum or exceeds a set limit, I cannot say.