CPAP Machines or Flow Generators are the brains of your sleep apnoea therapy and come in 3 diffent categories. These 3 categories are Fixed Pressure (CPAP), Automatic Pressure (APAP) and Bi-Level (BPAP or VPAP). Each of which have a different delivery method of therapy and will be determined by to refering specialist.
Fixed Pressure Machines are set to a specific therapy pressure. This is based on the script from your sleep study.
Automatic Machines are set with a min. and max. pressure based on the script from your sleep study. The machine will measure each breath you take and based on the shape of that breath, and will adjust your treatment as needed.
Bi-Level Machines produce 2 levels of pressure to treat sleep apnoea. An inspiratory pressure (IPAP) and an expiratory pressure (EPAP). This simply means that a pressure delivered upon inhalation is higher than the pressure upon breathing out and is beneficial to person that has trouble exhaling against standard CPAP pressure.