Yes. The CPAP machine records info while you use the machine during the night. This info is viewed by the 'sleep' nurse that monitors your condition. You need to be using it to an adequate level before you will be accepted as 'fit' for surgery.
There are a pain to get used to sleeping with but they really do work and have a positive impact on quality of life. Ask the nurse for options that may make your adjustment to this unit more comfortable, such as 'nose pillows' that fit just in the nose. Apparently much more easier to get along with than a full face mask - being a mouth breather, I had to make do with the full face mask, but it did get eaiser.
There can also provide a humidifier that attaches to your CPAP and apparently they make a difference, but I've never used one.
Good luck