The use of a CPAP machine

Sleep apnea is a situation of cumulative pikuah nefesh, meaning that if not treated the patient will eventually end up in an ICU. However, not using it for even one night can give rise to a possibility of pikuah nefesh depending on many other factors and therefore MUST be used every night. Where possible use a Shabbos clock to turn it on and off, or else use the back of your finger to do so if you have to disconnect in the middle of the night.

There is no distinction between machines that need a button to start versus machines that start when the mask is attached, if both actions (pressing the button or attaching the mask) can be done B'shinui.

Refuah Shlema