There are four main types of Positive Airway Pressure machines, which vary from most to least technologically involved. Your most common options for PAP therapy include the following:
Continuous Positive Airway Pressure (CPAP)
Bi-Level Positive Airway Pressure (BiPAP)
Auto Adjusting Positive Airway Pressure (APAP)
Adaptive Servo Ventilation (ASV).