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. 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.
In most cases of obstructive sleep apnea, CPAP alone is sufficient as a therapy, but in more complicated scenarios, BiPAP may prove to be a useful alternative.
Sources:
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.
