There are many types of CPAP devices.
Fixed pressure CPAP device
This type of CPAP machine is set with a fixed pressure based on the pressure level the patient requires to prevent apneas and hypopneas based on a titration to effectively treat sleep apnea.
Automatic CPAP device
This type of device is set at a range of pressures that will increase or decrease the pressure as needed throughout the night to treat obstructive sleep apnea.
Bi-level positive airway pressure device (also called BPAP)
The bi-level device works just like the fixed and automatic CPAP devices, except that it delivers pressure at two levels: one for inhaling and another for exhaling. The pressure when exhaling is lower in order to make it easier to breathe.It is mostly used by people who need a higher positive pressure, providing them more comfort and tolerance of the treatment.