BiPAP is a method of breathing support that is often used to treat central sleep apnea. It may also be used in more severe obstructive sleep apnea, especially if mixed apnea events are present, suggesting a component of central sleep apnea. It may be used to treat people who cannot tolerate continuous positive airway pressure (CPAP), especially those who complain that it is difficult to breathe out against the pressure. It may help to improve compliance. In addition, it is a non-invasive means of support that can be used in hospitalized people who are in respiratory distress but who do not wish to placed on a ventilator.
Many of the components of a BiPAP machine are the same as the standard CPAP machine. The key distinguishing feature of BiPAP is that the pressurized air is delivered at two alternating levels. The inspiratory positive airway pressure is higher and supports a breath as it is taken in. Conversely, the expiratory positive airway pressure is a lower pressure that allows you to breathe out. These pressures are preset and alternate just like your breathing pattern.
There is some confusion about the word BiPAP itself, especially how it differs from bilevel. These are actually the same thing. One of the major manufacturers of these devices, Respironics, has registered BiPAP as a trademark name for the technology that is generically called bilevel. The other major competitor, ResMed, calls similar devices VPAP.
In most cases of obstructive sleep apnea, CPAP alone is sufficient as a therapy. In more complicated scenarios, or when it is difficult to tolerate CPAP, BiPAP may prove to be a useful alternative. If you are curious whether it would be an appropriate therapy for you, you can start by speaking with your sleep doctor.
Kryger, MH et al. "Principles and Practice of Sleep Medicine." Elsevier, 5th edition.
Reeves-Hoche, MK et al. "Continuous versus bilevel positive airway pressure for obstructive sleep apnea." Am J Respir Crit Care Med 1995;151:443.