BiPAP stands for Bilevel Positive Airway Pressure, and is very similar in function & design to a CPAP machine. Unlike a CPAP Machine which delivers a constant standard pressure, but in a BiPAP machine there are two pressure settings. One pressure is for inhalation (IPAP), and other is for lower pressure that is for exhalation (EPAP). When you breathe in, the pressure will increases in a prescribed amount, & lower during exhalation. Many people found tolerating PAP therapy easier with a Bi-Level machine, and have been prescribed this is a specific therapy by their physician. Other names of Bi-Level machine is BiPAP & VPAP.