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How does a CPAP machine work?

In order to treat it, the simplest, and most effective,solution is to use a mechanical therapy that falls under the category of positive airway pressure (PAP).

CPAP, APAP, BiPAP, and ASV are all versions of this kind of therapy.

How these different PAP treatments work relates to how sleep apnea occurs in the first place.Let’s review what sleep apnea is, how a PAP machine operates, and how the mechanisms of this therapy treat OSA.

Sleep apnea 101

At night as you sleep, your brain switches to an automated system that allows you to breathe once you are unconscious.However, if your body experiences obstacles to breathing as you sleep, it will wake itself up so that you can consciously take a breath to remove these obstacles.

What is sleep apnea?

An apnea is a pause in breathing that lasts more than 10 seconds and which leads to an unhealthy drop in blood oxygen. Sleep apnea, as the name suggests, occurs only as you sleep.

In the case of obstructive sleep apnea (OSA),there is an obstruction in the upper airway that is blocking the passage of air into or out of your lungs as you sleep.

The body itself may continue to try to breathe, but the obstruction prevents any oxygen from entering the bloodstream (or any carbon dioxide from being exhaled).

This creates a chemical imbalance in the body which leads to alerts to the brain to “wake up” to breathe.

What causes these obstructions?

The most common obstructions during an apnea take place in the upper airway at the back of the throat. The tissue is relaxed here during sleep, which can lead to problems if the tongue has dropped into the back of the throat, or the airway itself has been crowded by overlarge tonsils or uvula.

Some people also have very narrow passage ways to begin with, and the space itself is compromised during sleep for this reason.

Those with added fat around their neck, while in a supine position (on the back) are also vulnerable, as gravity and weight press against the soft, often floppy, tissues surrounding the airway, creating obstruction.

And any time the tissues of the airway are inflamed or swollen or otherwise affected (such as congestion, allergies, or asthma), the risks for encountering obstructive apneas go up.

What is central apnea?

In the case of central sleep apnea (CA), the signals from the brain to the diaphragm to breathe as you sleep are thwarted, leading to no airflow and no effort to breathe. Eventually, the same alarms are sounded in the body and the brain sends you back to consciousness to take a necessary breath to correct the problem. CA is not a mechanical problem, then, but a neurological one.

CPAP to the rescue

You can think of CPAP as a kind of “pneumatic splint.” Positive airway pressure forces a stream of pressurized air into the back of the throat which helps keep the airway open and the tissues firm, rather than floppy. When you use CPAP, it’s not actually breathing for you, it’s just helping to recreate the proper conditions so that you can breathe for yourself.

How CPAP machines work

The original CPAP machine was devised using a reversed vacuum cleaner technology back in the 1980s, believe it or not. The concept still works, though today’s machines are far more sophisticated and comfortable to use.

Here’s how it’s done:

  • Inside the machine is a simple motor which draws air in from the room, then pressurizes it

  • Once the “room air” is pressurized, it’s sent(usually) through a humidification chamber, which warms and moisturizes it to make it more comfortable to the airway

  • This humidified air is sent by way of a length of tubing to the CPAP mask to deliver directly to the user through the nose (or, in the case of full-face masks, through both nose and mouth)

  • The incoming stream of air pressure opens up the airway and allows you to breathe independently while asleep, without obstruction

How much pressure is delivered?

Pressurized air is metered by a preset number that has been programmed into the CPAP machine by asleep specialist. For many people, the force of the air is gentle, but effective.

Others with moderate to severe sleep apnea may have higher settings or more complicated sleep-breathing problems which lend themselves to the use of the other PAP therapies, such as BiPAP or ASV. The only way to know which therapy works best for you is through testing and consultation with a sleep specialist.

Bottom line: CPAP saves lives

For millions of people with sleep apnea, PAP has become a lifesaver in this way.

In fact, at sleep centers everywhere, there is a common refrain among long-time CPAP users: “I won’t sleep without it!” CPAP support groups are a great way to connect with these “super users.”

Despite the challenges that some have with adjusting to the therapy, it still remains the most simple, effective, and noninvasive way to treat sleep apnea.

While some discomfort may temporarily be part of the experience, the long-term effects of untreated sleep apnea are far worse. Brain damage, hypertension, mood disorders, sleep deprivation, heart disease, and diabetes are just a few of the problems you can expect.

Treating sleep apnea is as simple as understanding its mechanical dysfunction and correcting it using a mechanical therapy. CPAP and its other cousins in the PAP lineup of therapies are considered the first line of defense against sleep apnea precisely for this reason: these approaches are simple, noninvasive, and effective.


If you suspect you might have sleep apnea, please consider addressing your concern with a sleep specialist. In the meantime, if you aren’t sure, you can take the easy, free sleep apnea test below to determine whether you might have a problem.

Further Reading

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