BILEVEL THERAPY Many of the components of a BiPAP machine are the same as the standard CPAP machine. For example, it still requires a face mask and tubing connected to the device. The key distinguishing feature of BiPAP is that the pressurized air is delivered at two alternating levels.
The inspiratory positive airway pressure (IPAP) is higher and supports a breath as it is taken in. Conversely, the expiratory positive airway pressure (EPAP) is a lower pressure that allows you to comfortably breathe out. These pressures are preset based on a prescription provided by your sleep doctor and alternate just like your breathing pattern.
Beyond these standard settings, there are a few other variations that are available. Bilevel ST includes the timed delivery of a breath if breathing pauses occur. These pauses are often present in central sleep apnea.
In addition, auto or adaptive servo-ventilation (ASV) includes more sophisticated settings that vary the timing, length, and volume of the breaths that are delivered.