The Differences Between Oxygen Concentrators and CPAP Machines (2025)

If you need both an oxygen concentrator and a continuous positive airway pressure (or CPAP) machine, you might be wondering: What is the difference? While these therapies seem similar and sometimes treat the same disease, they are different in many ways.

In this brief blog post, we will discuss the main differences between an oxygen concentrator and a CPAP machine. We will also discuss some scenarios in which these therapeutic devices might overlap.

What is an Oxygen Concentrator?

An oxygen concentrator is a standalone or portable device that draws in ambient air, filters out the nitrogen, and expels the remaining oxygen as a concentrated gas. The primary function of an oxygen concentrator is to deliver more oxygen than what is available in the ambient air.

The air we breathe is made up of 21% oxygen and 79% nitrogen, with some trace gases mixed in. In certain disease states such as chronic obstructive pulmonary disease (COPD) or pulmonary fibrosis, the body requires more oxygen than what is available in the ambient air. So to meet that requirement, an oxygen concentrator creates a concentrated source of almost pure oxygen to raise the percentage of ambient oxygen to anywhere from 87%–100% oxygen depending on the manufacturer. This concentrated oxygen is then breathed in via a nasal cannula or oxygen mask to increase the amount of oxygen in the body. Depending on your needs, this concentrated oxygen can be delivered in a continuous flow (more oxygen) or as intermittent, or pulse-dose, flow (less oxygen).

To determine whether you need supplemental oxygen via an oxygen concentrator, your doctor might order several tests to determine the baseline level of oxygen in your blood and if it changes during mild exertion. These tests include a pulmonary function test (to test the overall function of your lungs), an arterial blood gas (to determine how much oxygen is in your blood at rest), a pulse-oximetry stress test (to measure changes in your oxygen level following a brief walk), and a chest x-ray.

What is a CPAP Machine?

A CPAP machine is a standalone device that compresses ambient air to generate pressure for therapeutic purposes. It is widely used at home to treat obstructive sleep apnea (OSA), but it can also be used in emergency settings in a hospital by a respiratory therapist.

With OSA, the primary problem is that the throat collapses while sleeping, causing the patient to snore. While snoring is often seen as a humorous act in movies, this repeated collapsing of the throat actually obstructs airflow into the lungs, which can eventually lead to dangerously low oxygen levels in the blood.

If OSA is the only clinical problem (outside of any other lung disease), then using a CPAP machine is generally sufficient to reverse the problem. The pressure generated by the CPAP machine flows through the CPAP tubing, into a face or nose mask, and then into your lungs. This pressure acts like a stent in the back of your throat, which keeps your throat from collapsing during sleep. If you have ever set up a camping tent, the pressure from a CPAP machine functions similarly to the framework inside the fabric of the tent, which keeps the tent open and prevents it from collapsing on itself.

What Is the Difference Between an Oxygen Concentrator and CPAP Machine?

There are 2 main differences between an oxygen concentrator and a CPAP machine:

• The concentration of oxygen in the air flow
• The amount of pressure flowing through the tubing

As described earlier, the primary function of an oxygen concentrator is to increase the percentage of oxygen in the ambient air. A CPAP machine, however, will not increase the amount of oxygen in the airflow it generates. While a CPAP machine produces a higher pressure of ambient air, the oxygen concentration remains at 21%.

To address the second point, while an oxygen concentrator increases the ambient level of oxygen in the air to anywhere from 87%–100%, it does not generate enough pressure to keep the throat open in the presence of OSA.

Can They Be Used Together?

While these 2 devices function differently, CPAP machines and oxygen concentrators can also be used together for certain conditions. For example, if you have a lung problem like pulmonary edema or COPD on top of OSA, it might be necessary to add in oxygen to the tubing of your CPAP machine. This will achieve both functions at the same time: increasing the amount of oxygen in the ambient air and also generating enough pressure to keep the throat open.

Final Thoughts

It can be confusing at first to understand the differences between these 2 devices because they are used in many of the same scenarios. Hopefully, this overview has given you some insight into how they are different so you can make more informed decisions with your healthcare provider.

Looking for more information?

• Call Us at 877.774.9271
• View our CPAP Machine Buying Guide
• Intro to Travel CPAP Machines
• How To: Connect a CPAP Machine to Your Oxygen Concentrator

Updated: September 9, 2024
Published: April 13, 2019

About Ryan Anthony:

Ryan Anthony, BS, RRT is a registered respiratory therapist and content writer and medical blogger currently located in Los Angeles, California. As a Respiratory Therapist, he performs a wide range of hospital duties including adult and neonatal intensive care, nitric oxide therapy, high-frequency oscillatory ventilation, conventional mechanical ventilation, noninvasive ventilation, BiPAP, CPAP, intubation assistance, bronchoscopy assistance, cardiopulmonary resuscitation, chest physiotherapy, and nebulizer therapy.