What Is the Difference Between CPAP and BiPAP Therapy for Sleep Apnea?

Device Pressure Settings Vary and Treat Different Sleep Apnea Conditions

CPAP and BiPAP (or bilevel) therapy are used to treat obstructive and central sleep apnea
CPAP and BiPAP (or bilevel) therapy are used to treat obstructive and central sleep apnea. Brandon Peters, M.D.

If you have been diagnosed with sleep apnea, you have likely been introduced to at least one of the possible treatment options. The most common (and effective) therapy is continuous positive airway pressure (CPAP). You may also be curious to know the difference between two similar treatment options: CPAP and BiPAP (or bilevel) therapy. Discover more information about these therapy devices and which one might be right for you.

What Is CPAP?

The standard treatment for obstructive sleep apnea is the use of a machine that provides support to keep your airway open while you are asleep. This can be accomplished with continuous positive airway pressure (CPAP) in which a constant flow of air is provided via a face mask. How does CPAP work to treat sleep apnea and what pressure is needed? The pressure setting of this airflow is often determined by a doctor based on your needs. This may be evaluated as part of sleep study or can be estimated based on your risk factors, such as your anatomy and weight. An effective pressure setting is meant to prevent both apnea and snoring, as well as the other symptoms associated with sleep apnea.

What Is BiPAP?

A similar therapy is called BiPAP, but it differs in important ways. BiPAP is an abbreviation trademarked by the manufacturer Respironics for bilevel positive airway pressure. (It is called VPAP by the other major manufacturer, ResMed.) The "bilevel" component refers to the fact that there are in fact two pressures, which the machine is able to alternate between.

This allows you to breathe out against a slightly lower pressure. Aside from a label or different color, from the outside the machine may not look significantly different from a CPAP. It still requires the same tubing and face mask that is used in CPAP therapy. It can be more effective in select circumstances, however.

Do I Need CPAP or BiPAP?

People with the most common form of sleep apnea usually start treatment with CPAP. BiPAP is more often used to treat central sleep apnea. This condition is characterized by pauses in breathing without obstruction of the airway, and is identified as part of a sleep study. The BiPAP device may be set to compensate for these pauses in breathing by kicking in an extra breath as needed. BiPAP may also be used if you are unable to tolerate using a CPAP machine due to discomfort breathing out against the higher pressure.

Are There Other Machine Options?

Beyond CPAP and BiPAP, there are additional settings of the machines that can be ordered by your sleep specialist. Many machines, often with the prefix "Auto," have an automatic feature that allow a range of pressures to be used. The device is able to respond to subtle collapses in the airway and can turn up the pressure as needed during the night.

There is also a type of bilevel that can deliver timed breaths (often called bilevel ST).

Finally, there is another sophisticated machine called auto or adaptive servo ventilation (ASV) that has even more features to maintain normal breathing in sleep. These devices are often reserved for people who need extra ventilatory support due to underlying neuromuscular, cardiac, or pulmonary disease.

How do you sort this out? Luckily, you don't have to! Your sleep specialist should be able to make the determination of your needs based on the results of your sleep study and your assessment in the clinic. Discuss your options at your visit and be in close contact if you experience any difficulties with the treatment of your sleep apnea. Based on usage data, if changes in your therapy are required, these can be arranged when you are seen in routine follow up.

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