We don't have a 12V receptacle in the bedroom area, but there is 12V wiring runnning in the walls around the bedroom area - a hot lead in the wall at the head of the bed running to our outside shower's remote water pump switch, and a hot lead in the wall at the foot of the bed running to our outside entertainment center's outside 12V receptacle.
I'm too lazy to tap into these though ... why do it ... plus then have to buy an expensive voltage converter brick for the CPAP. Instead we just do what I mentioned earlier - string an extension cord to the bedroom area from our small pure sine wave inverter that we already have for other things.
K.I.S.S. really does make life easier at times.