Fixed Pressure/Manual CPAP Machines have been around since the beginning. A CPAP machine is an electro-mechanical device designed to deliver a predetermined and precise amount of constant pressure to the nasal airway, keeping the airway open. Think of it as a pneumatic splint that keeps the airway from collapsing while you sleep. Users will often confuse Fixed Pressure/Manual CPAP with an Auto CPAP machine due to the ramp feature on their device, don't be confused! A Fixed pressure machine for sleep apnea only generates one specific setting and stays at that number through the course of the night.