I don't see how they can say that a CPAP draws more power than a laptop.
Neither can I! It's probably just their 'get-out' clause!
I went to a specialist battery shop and asked for a supplemental lbattery suitable for a laptop. It came with a charger lead to attach it to the mains supply and a separate lead to connect the charged battery to the cpap. It is about the size of a small paperback book and is light. It cost me about 170€ (I live in France) but Maplins in the UK sell one about the size of an A4 sheet of paper for about £80.
Make sure you take your cpap technical manual to the battery shop to check the voltage required. The consumption of your CPAP and the pressure you use it at plus the capacity of the battery can give you some idea of how long the charged battery can run your cpap. Make sure you know how long the battery needs to be recharged.
I hope that this helps. I sit my battery on top of my CPAP on the dropdown table and there are no trailing leads .......... just my hose!!
Happy landings!