BiPAP and CPAP each generate positive airway pressure for the treatment of sleep apnea. CPAP machines provide a single constant pressure during inhalation and exhalation. BiPAP, or BiLevel, on the other hand, provides two different pressures, one during inhalation and the other during exhalation. Obstructive sleep apnea patients will use CPAP most often. Patients with central sleep apnea will use will use BiPAP most often.
Theory
The theory behind positive airway pressure is to prevent apnea by keeping the airway open. This approach also supports the process of respiration by keeping a constant level of oxygen in the cells to prevent cell damage or death. Originally developed in 1981 to support patients suffering from sleep apnea, positive airway pressure is also used in the acute care setting to provide short-term ventilatory support.
Significance
According to MayoClinic.com, central sleep apnea occurs when a person temporarily stops and starts breathing throughout their sleep cycle because the brain is not sending adequate signals to the respiratory center to breathe. Obstructive sleep apnea occurs when the soft tissue of the upper airway relaxes, closing off the trachea during sleep. Both forms of apnea can lower the blood oxygen levels in the body. BiLevel and CPAP treatment can reduce or even eliminate the affects of sleep apnea.
System Components
Components of a positive airway pressure system include the flow generator, or the actual BiLevel or CPAP machine, which provides the airflow through a breathing circuit to the patient interface. The patient interface is a mask or soft latex or rubber nasal prongs that fit snugly into the nasal openings. The breathing circuit connects the flow generator to the patient's mask or nasal prongs.
Effects of BiLevel
BiLevel positive airway pressure provides breathing support to patients most often diagnosed with central sleep apnea. According to the Cleveland Clinic, a BiPAP machine delivers a lower expiratory pressure, making it easier to breathe out, and a higher inspiratory pressure to keep the airway open during inhalation. There are three modes to BiPAP: spontaneous, where the machine triggers inspiratory pressure as it senses a person taking a breath; timed, where a specific breaths-per-minute rate is set; and spontaneous/timed, which is a setting where the machine initiates a breath when the patient fails to initiate one on his own.
Effects of CPAP
Continuous positive airway pressure, or CPAP, provides a fixed, preset pressure during inhalation and exhalation for patients most often diagnosed with obstructive sleep apnea. According to the National Heart, Lung and Blood Institute, CPAP is the most common treatment for this type of sleep disorder. Patients with obstructive sleep apnea use CPAP machines in their homes. These machines are by prescription only and most often prescribed after completing a test called a sleep study, or polysomnography.
