I've used a CPAP machine on 50+ long haul, business and first class CX flights during the past three years. Other than the occasional issue with the seat power supply not functioning, I've never had a problem or so much as a comment from the crew. I've never informed CX about my CPAP or sought any special permission. I occasionally use a battery operated machine (as a backup in case the seat power is out), but 90pc of the time I'm plugged in and snoozing in comfort.

For those not familiar with CPAP, the units are practically silent and the one I use is the size of a book. It sits beside me on the seat and doesn't bother anyone. The air hose and headgear look a bit odd, but that's more comic relief than inconvenience for the other passengers.