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BiPAP vs CPAP: Which One is Best?

One of the most common questions our patients ask is “what is the difference between CPAP and BiPAP?” Both machines use positive airway pressure (PAP) therapy to keep your airways open while you sleep. Both can can be used with a full face mask, nasal mask, and nasal pillows.  Yet for some, the difference between the two is the key to better sleep. 

If CPAP therapy just isn't working for you, a BiPAP could be the solution you need. Keep reading to find out if BiPAP therapy is right for you.

How Does CPAP Work?

CPAP stands for Continuous Positive Airway Pressure because CPAP machines have a “fixed” or constant level of pressure. This constant stream is used to keep the airway open during sleep, thus preventing apneas, or pauses in breathing due to relaxed muscle tissue in the laryngeal/tracheal region. CPAP devices are the most commonly prescribed treatment for Obstructive Sleep Apnea (OSA) because CPAP therapy is the most effective non-invasive option.

A CPAP delivers only your prescribed air pressure level throughout the night. However, many CPAP machines now come with a feature called Exhalation Pressure Relief (EPR) which can lower the incoming pressure as you exhale for a more natural breathing sensation. At first glance this may seem like the same thing that a BiPAP machine does, so why the distinction? Let’s get into how a BiPAP machine works, and what sets it apart.

How Does BiPAP Work?

BiPAP machines – or Bilevel Positive Airway Pressure– are different from CPAP machines because, as the name suggests, it has two set levels of pressure. 

The first level of pressure is inspiratory positive airway pressure (IPAP). This higher pressure level is applied during inhalation to keep the air passage open. The second level of pressure is expiratory positive airway pressure or (EPAP), and this lower pressure level is more natural to help with exhaling. While this may seem like the same thing CPAP machine with an EPR feature does, it’s actually not.

Both inhalation and exhalation pressure levels are indicated for people who use BiPAP, where as CPAP patients will only have one pressure set. With EPR, the pressure lowers slightly on exhalation, but always in proportion to your prescribed pressure level. But with BiPAP, the exhalation pressure level is a completely separate pressure level set by your sleep specialist.

The lower pressure during exhalation provided by both CPAP with EPR and BiPAP may help to avoid some potential side effects of PAP therapy, such as difficulty exhaling, bloating, dry mouth, and sinus discomfort.

BiPAP machines are more typically prescribed to patients who need higher than normal pressure or have additional health concerns. These may be more complicated sleep disorders, such as Central Sleep Apnea or Complex Sleep Apnea, or cardiopulmonary conditions such as Chronic Obstructive Pulmonary Disease (COPD) or a history of congestive heart failure.


The machines may look identical, but now you can see that the difference between the two is in how they use pressurized air. It may seem like the BiPAP is the better way to go since both IPAP and EPAP levels are customized. A more advanced machine = better treatment right? But BiPAP may not be right for you. It’s usually more expensive than a CPAP machine and typically used for more complicated conditions or situations. If adjusting to the airflow is your only concern, you may be better off with an APAP, or Automatic Airway Pressure Machine.

What is APAP?

APAP stands for “automatic positive airway pressure. It’s also sometimes referred to as an Auto CPAP. PAP technology has advanced so much in the last few years that most new CPAPs have automatic pressure adjusting functionality. But since ‘CPAP’ is so widely used as a catchall term, you may see APAP machines listed as CPAP machines. In fact, most of the machines we offer on our CPAP machines page have auto-adjusting functionality.

When you use an APAP, your healthcare provider will prescribe an air pressure range and then the machine uses an algorithm to choose the pressure you need at any given time. 

You should always consult your healthcare provider if you want to explore a new type of PAP therapy or if you are having trouble adjusting.

Consider a BiPAP Machine

If you are having trouble adjusting to your CPAP machine, there are a few things to try before choosing a different treatment option:

  • Make sure that you have a well-fitting CPAP mask. Many patients cannot tolerate their machine simply because they have a mask that does not properly fit them. Use our handy mask fit guide to ensure that you get a great fit.
  • Check your humidity level and remember to use your ramp button. The ramp feature will lower your pressure and slowly work its way back up, giving you time to fall asleep at a comfortable pressure.If you are still having trouble with your CPAP machine, it may mean that you are a BiPAP candidate. BiPAP machines are a great option if you require a high-pressure setting.

CPAPSupplies.com carries a great selection of BiPAP machines. No matter what needs you have when it comes to sleep apnea treatment, we'll help you find the best equipment at the right price.