CPAP Therapy

What Is an Automatic Positive Airway Pressure (APAP) Machine? (Uses and Benefits)

If you’ve been diagnosed recently with Obstructive Sleep Apnea—or if you think you have Sleep Apnea, but are not yet diagnosed—you may be feeling confused about the differences between the various Sleep Apnea machines (sometimes referred to as PAP machines, or Positive Airway Pressure machines).

Most people with apnea use a CPAP (Continuous Positive Airway Pressure) machine, but CPAP isn’t the ideal choice for every user. Individual treatment needs can vary. Some apnea patients will see better results by using a BiPAP/BPAP (Bilevel Positive Airway Pressure) machine and others will benefit more from using an APAP (Automatic Positive Airway Pressure) machine.

In this article, we’ll take a look at what an APAP machine is, why you’d use it to treat your apnea or sleep-disordered breathing, and what the benefits are from this therapy.

What Is an APAP Machine?

The acronym APAP is short for Automatic Positive Airway Pressure. APAP machines adjust air pressure automatically so that you can receive the minimum amount of pressure needed to keep your airways open.

The general principle behind CPAP, BiPAP, and APAP is the same in all three cases: pressurized, filtered air keeps your airway from collapsing during sleep, allowing you to breathe without interruption.

By using an apnea machine like APAP, you’ll be able to breathe without apnea events—those cessations of breathing that lead to multiple nighttime awakenings per hour throughout the night. Apnea machines can also help to treat upper airway resistance syndrome (UARS), a precursor to Sleep Apnea that narrows, rather than blocks, your airway.

All PAP machines consist of three main components:

  1. a motor that pressurizes, filters, and humidifies (if you want it to) room air
  2. tubing through which this pressurized air travels until it gets to. . .
  3. an apnea mask that you wear while sleeping

The difference between the three types of machines is in the pressure settings.

Depending on the severity of your apnea and any underlying health issues you may have that affect your breathing, you may benefit from one style of air pressure setting more than another.

How Does an APAP Machine Work?

Sleep Apnea experts frequently hear this question: “APAP vs. CPAP: what’s the difference between these apnea machines? If they all do the same thing, why choose APAP for my apnea instead of CPAP?” The difference is in the air pressure settings.

CPAP: Single Pressure Setting

CPAP therapy, the gold standard for treating most cases of obstructive apnea, provides a continuous, steady flow of air at a single pressure. This pressure setting is the exact level of air pressure required to clear the airway of obstructions. A CPAP machine user will have their own individual pressure setting, determined by their doctor during their CPAP titration study (an overnight study where you wear your apnea mask to sleep, and technologists observe you and adjust your air pressure until it’s precisely what you need).

This set air pressure level can be adjusted in the future if needed—for example, if your Sleep Apnea worsens and you need greater air pressure to clear your airway—but these changes are prescribed and need to be changed by your doctor or technicians in the sleep clinic.

APAP: Automatic Range of Pressures

The pressure delivered by an APAP machine automatically changes as needed to deliver the minimal pressure required to maintain the airway. Your doctor will set a minimum air pressure setting range and a maximum air pressure setting range. After that, sophisticated algorithms automatically determine which level of air pressure you need at any given moment during the night, and the APAP machine makes the necessary adjustments.

No titration study is required. This type of apnea therapy is helpful for people with varying breathing patterns. If for some reason you don’t respond well to APAP therapy, your doctor can reset the machine to function like a CPAP, delivering continuous pressure instead.

Which apnea machine is best for you depends primarily on your comfort level.

Uses of APAP (Reasons and Indications)

What is APAP used for? You might choose APAP therapy if you have one of the following situations or indications:

Your apnea events increase in REM sleep.

During REM sleep, your throat muscles relax and may become flaccid or paralyzed, leading to an airway obstruction. If you use CPAP, your machine is adjusted to provide you sufficient air pressure to overcome this obstruction—but that air pressure stays with you all night long, even during the other sleep stages.

Some users find this constant high air pressure to be uncomfortable. APAP can adjust by delivering higher pressure during REM sleep and lower pressure during other sleep stages.

You switch sleep positions during the night.

Are you a side sleeper or a back sleeper—or do you switch between each position? Moving around in the night can lead to changing pressure requirements. Some people with apnea need a higher pressure setting when sleeping on their backs vs. their sides. (Gravity pulls the loose tissue toward the back of your throat, creating a blockage.) An APAP can adjust automatically by reducing the air pressure setting when you roll onto your side.

You’ve been diagnosed via a Home Sleep Test (HST).

If you live far away from a sleep center or your health insurance does not cover the cost of a full polysomnogram and overnight sleep study at a sleep center, perhaps you’ve opted for a home sleep test as an alternative. If your HST diagnoses with you apnea, you may be able to start out treatment quickly with an auto-adjusting APAP. This also allows you to begin treatment without going to a sleep center for a CPAP titration study.

Benefits of Using APAP to Treat Apnea

Perhaps the chief benefit of using an APAP is that you do not need to stay on the fixed higher pressure of CPAP over the course of a single night. Using APAP means your overall pressure can be significantly less. For some people who are sensitive to higher air pressures (for example, if you feel claustrophobic), this variable pressure setting may mean more comfort and a better night’s sleep.

APAP is also helpful if you experience night-to night-variability in your air pressure needs. For example, if you have seasonal or situational allergies or a cold, sometimes you’ll want more or less air pressure depending on your level of congestion.

If you’ve been drinking alcohol, you may need more air pressure that night to compensate for the resulting flaccidity of your muscle tissue (because alcohol is a depressant).

The APAP machine can adjust on its own for these conditions, whereas CPAP and BiPAP cannot.

Costs: Is an APAP Machine More Expensive than a CPAP Machine?

APAP devices themselves do cost more than CPAP devices, but the long-term cost benefits can more than make up for the cost differences at the start.

For one, you can use an APAP with no need for a CPAP titration study. This can save you co-pay and time (since a titration study is an overnight commitment).

Also, the increased comfort when you choose APAP may improve your compliance, which can mean fewer follow-up appointments and better insurance coverage for your therapy.


APAP machines have the same therapeutic goal as CPAP and BiPAP, but with a difference: they can automatically adjust air pressure to suit your changing needs as you sleep. APAP machines also do not require a CPAP titration study, meaning you can begin therapy faster and may save on costs and time. Some users choose APAP because they feel the variable air pressures make the treatment more comfortable and therefore easier to use.

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  1. Enjoyed your article very much as I am about to try an APAP machine very soon. I have been using a CPAP machine for the last 5 yrs and after a recent tritation study, the results show that an APAP machine would possibly benefit me better for my UARS than a standard CPAP one.

    • Hey JY, that is great news. A lot of of customers find themselves transitioning to an APAP. It may take some getting use to, but it usually works out well. Please let us know if we can be of any assistance with the machine change.

      We wish you the best!

  2. Franco mobilia Reply

    Mi mandate articoli interessanti in inglese, ma io nn lo conosco e non capisco niente
    Nn potete inviarmi questo articolo tradotto in italiano ??


    I bought from you an APAP S10 machine from ResMed, and I would like to obtain the Catalog that will allow my Doctor to set the upper limit of pressure, as it consistently exceeds the maximum recommended pressure the tests at the Hospital found to to be healthy. Will you help me?


    I bought from you an APAP S10 by ResMed and I would like to obtain a setting Manual that may allow my Doctor to set the upper limit of the pressure range, as it consistently raises up to a point, usually at 17,5 cm pressure, when I wake up under a very uncomfortable and risk condition, as the test performed at Fundación Neumológica de Colombia, in Bogotá, report a maximum desirable pressure of 10 cm.
    I am sure you will help me, as I am an old customer of yours.

    Thank you,

    • Hello Alfredo, I have e-mailed the clinical manual for the AirSense 10. Please let us know if there is anything else we can help you with. We can be reached at: 1-800-356-5221.

      Have a great day

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