If you do require a CPAP machine to keep you from dying in your sleep then yes a CPAP machine must be made available to you in jail.
Any medically necessary equipment that you need while in jail including medicines must be provided to you while you're in jail.
You need to get your doctor to prove that you need the CPAP machine but when you get into jail and booked in then let the medical staff know that you require a CPAP machine and they should provide you with one or allow your CPAP machine to be brought to the jail by family members.
Most times though they should be able to get you a CPAP machine without needing to bring your own.