Bilevel Positive Airway Pressure (BiPAP) provides two levels of pressure: one for inhalation (IPAP) and a lower pressure during exhalation (EPAP). BiPAP machines usually costs more that a CPAP machines. A BiPAP is sometimes used with patients who have a higher than average CPAP pressure and/or who find breathing out against an increased pressure to be uncomfortable. Respironics shows that C-Flex can also help BiPAP therapy