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BiPAP Machines vs CPAP Machines: Differences, Settings, Pros and Cons

Sep 10, 2019 8:24:40 AM / by Kevin Asp

cpap vs bipap


It's likely you know at least a little something about continuous positive airway pressure, more widely known as CPAP.

It involves wearing a mask which delivers air to you as you sleep so that you don't have dangerous pauses (called apneas) in your breathing.

CPAP is only one of several kinds of therapeutic devices using positive airway pressure (PAP) therapy to treat sleep apnea. A second kind of therapy known as Bilevel PAP (BiPAP) also exists which helps people with severe sleep breathing disorders. 

Which is the right therapy for you? You'll know that answer once you understand the differences between the two: how they work, what problems they address, and who they're intended for.

What is CPAP?

This therapy remains the gold standard for treating obstructive sleep apnea (OSA), though other therapy options, like oral devices, exist. CPAP is used for people suffering from all severities of OSA. 

How does CPAP work?

A CPAP machine draws air in from the room, then pressurizes it to a predetermined setting. Then, it delivers this air pressure as a single continuous stream through the tubing and mask attached to the machine. You wear the mask to receive delivery of the PAP therapy. It helps keep your upper airway from collapsing as you sleep. When the tissues in the airway collapse, this leads to partial or complete obstructions of the airway. 

The result of this collapse are: 

  • precipitously low oxygen levels in the bloodstream
  • more effort to breathe
  • oxidative stress on the heart
  • disrupted sleep, which can lead to sleep deprivation
  • changes in the body related to low oxygen which disrupts insulin levels and other chemical imbalances

If apneas happen repeatedly night after night, you are at increased risk for stroke, high blood pressure, type 2 diabetes, heart disease, vascular disease, obesity, depression, and many other chronic health problems. 

What is BiPAP?

BiPAP stands for bilevel positive airway pressure. It is also sometimes* referred to as BPAP or Bilevel PAP. Its uses and appearance are similar to CPAP; what makes it different is how the machine is set.

How does BiPAP work?

BiPAP delivers two different pressures: one for inhalation (called inspiratory positive airway pressure, or IPAP) and another (lower) pressure for exhalation (called expiratory positive airway pressure, or EPAP).

Bilevel therapy also offers the benefit of additional modes of function:

  1. It can be set to match a person's breaths-per-minute rate through the Timed function
  2. It can be set to "sense" any significant shift in the user's breathing using the Spontaneous function, providing compensation by adjusting pressures so the person can maintain a steady airflow
  3. It can be set to incorporate both the Timed and Spontaneous functions

Some people do not tolerate CPAP well; either they find they cannot adjust to the pressure (which can be high), or they don't mind the incoming pressure, but struggle to exhale against it.

For these people, BiPAP's specialized modes help synchronize the breathing patterns of users more easily, and offerthe option of a lighter EPAP pressure to make it easier to exhale. 

BiPAP is also the therapy of choice for people who suffer with specific kinds of pulmonary disorders (in example: chronic obstructive pulmonary disorder, or COPD) or cardiovascular problems (such as congestive heart failure, or CHF). 

It can be especially useful in that it can treat both OSA and its neurological cousin, CSA. 

What is central sleep apnea?

Central sleep apnea (CSA) occurs when the brain, during sleep, fails to signal to the lungs to breathe. CSA occurs sometimes in response to using CPAP (usually this is temporary, as the brain adjusts to the "new help" that CPAP provides). It also occurs in people with neurological problems that impact the brain's ability to regulate breathing automatically during periods of sleep. 

Which therapy is best for me?

This depends upon what kind of sleep apnea you have, how severe it is, how well you can tolerate PAP therapy, and what other health conditions you may have. Your doctor will prescribe PAP therapy based on the outcome of your sleep study and other factors. 

Most patients generally start with CPAP if their biggest concern is OSA. Keep in mind, however, that if you start on CPAP but cannot use it because you struggle to tolerate it, the doctor may then "graduate" you to BiPAP to help you adjust and succeed at your therapy.

Patients who also show evidence of the less common CSA may also be started on a Bilevel PAP therapy device instead. 

Pros of CPAP: 

  • Less expensive than BiPAP
  • Simple settings
  • Effective for users with mild to moderate obstructive sleep apnea

Cons of CPAP: 

  • May be hard for some to tolerate, especially at higher pressures, leading to noncompliance
  • May not be as effective for people with severe OSA
  • Does not treat CSA

Pros of BiPAP:

  • Helps make PAP therapy tolerable for some, improving compliance
  • More sophisticated settings can be customized to user's specific needs
  • Effective for users with moderate to severe obstructive sleep apnea

Cons of BiPAP: 

  • More expensive than CPAP
  • Users cannot start on BiPAP, typically, until they "fail" CPAP
  • May lead to CSA in people originally diagnosed with OSA

In any case, you must use your therapy every night for it to work. If you don't practice compliance, you cannot expect to get better.

What is compliance, and why is it important?

No matter which PAP therapy you choose, you will need to use it for a minimum of 4 hours each night, for a minimum of 5 nights a week in order to show you are compliant. This is what physicians and insurers look for with all kinds of therapies. A patient who is noncompliant is not going to get better because they are not using their therapy.

For instance, if a person who is newly diagnosed with Type 2 diabetes doesn't check their blood sugar or use their insulin therapy as prescribed by their doctor, they will be defined as noncompliant. This matters not only to doctors, who want you to get better, but also to insurance companies, which are set up to reimburse for therapy. They will stop reimbursing for therapies if they deem that users are not applying them faithfully enough to make a difference in outcomes.

The same holds true for using CPAP or BiPAP. "Use it or lose it" may indeed become the new mantra as patient outcomes are more frequently measured by insurance carriers based on patients' compliance to their therapies.  

If you start out using CPAP and find you are not able to tolerate it, don't put your machine in a drawer and give up! You can always call your doctor and ask about using BiPAP to manage your difficulties with pressures.

It's important that you communicate your challenges to your sleep specialist or durable medical equipment (DME) provider in order to ensure you can remain on your therapy to meet compliance minimums but, more importantly, to derive the greatest benefit from your PAP therapy and feel better. 

Topics: bipap, cpap vs bipap, cpap

Kevin Asp

Written by Kevin Asp

Kevin Asp is the President and Founder of inboundMed and SomnoSure. He is the past founder and President of Alaska Sleep Clinic, touted as the most trafficked sleep center website in the world.

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