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What is oxygen therapy?

If you have been diagnosed with a disease that makes it hard to breathe, such as chronic obstructive pulmonary disease (COPD) or pulmonary fibrosis, you may have symptoms such as:

  • Shortness of breath, especially when you walk or exercise;
  • Cough;
  • Tiredness;
  • Headaches;
  • Swollen ankles when you get up in the morning; or
  • Blue fingertips or lips.

Low oxygen levels in your blood—a condition called hypoxemia—affects your body in several ways. Lung disease may significantly change the tubes in your lungs (called alveoli) or the space that surrounds the alveoli (called the interstitial space) in your lungs, which may cause your heart to pump harder to circulate blood—and therefore oxygen—through your body.

Low oxygen levels make it difficult to perform basic activities or even walk. All organs in your body depend on a good oxygen supply to function properly. Most importantly, low oxygen may affect your brain. You may notice, for example, that you have trouble paying attention or remembering things. You or your friends and family may even notice that you’re slurring your words.

Your health care provider will need to perform specific tests to qualify you for oxygen therapy. For example, your provider may order a blood test to see the oxygen content of your blood. You qualify for oxygen therapy under the following conditions:

  • If your saturated oxygen (SaO2) level on room air (that is, without oxygen) at rest while you’re awake is 88% or less as measured by a pulse oximeter (a small, noninvasive device that clips onto your finger and measures the amount of oxygen in your blood) or is 55 mm Hg or less as measured by a blood test, you qualify for continuous oxygen therapy.

    If your SaO2 level on room air at rest while you’re awake is above 88%, your health care provider may check your SaO2:
      •  At rest on room air;
      •  With exertion on room air;
      •  With exertion on oxygen; and
      •  At rest after exertion on oxygen.

    If your SaO2 is 88% or less after these tests, you qualify for oxygen therapy.
  • If after these tests in the provider’s office or hospital your SaO2 doesn’t drop below 88%, your provider may want to monitor your SaO2 levels while you’re sleeping, called nocturnal oximetry.

    Your provider will send an order to a durable medical equipment (DME) supplier. The DME supplier, working with a testing company, will send you a pulse oximeter. You sleep with the device clipped to your finger. While you’re sleeping, the oximeter records your oxygen levels. The next day, you return the oximeter to the DME supplier, and the testing company will send the results to your health care provider.

    If your SaO2 is 88% or less for 5 minutes, you qualify for nocturnal oxygen only. In this case, the DME supplier will send you a stationary oxygen concentrator (see “Stationary oxygen therapy systems” for more information) and backup oxygen cylinders in case of a power outage.

  • If your SaO2 at rest is above 88% as measured by a pulse oximeter both while you’re awake and while you sleep but you still have trouble breathing, you will need to meet additional criteria, such as:
      •  Have evidence of edema, which may suggest heart failure
      •  Have evidence of pulmonary hypertension or right heart failure
      •  Have elevated blood counts, with a hematocrit level greater than 56%

Depending on the results of these tests, your health care provider may prescribe oxygen therapy. This supplemental oxygen is delivered by an oxygen therapy system.


Please see Paying for Oxygen Therapy for information about Medicare and private insurance reimbursement for oxygen therapy.

Your oxygen therapy prescription

When your health care provider prescribes oxygen, the prescription should include the following information:

  • How often you should use your oxygen therapy system
  • How many liters a day of oxygen you should use
  • The type of flow rate (continuous or pulsed flow)
  • When you should use oxygen (for example, all day, only when you’re walking around, only when you’re sleeping)
  • The type of oxygen therapy system you need and how often you’ll need replacement supplies
  • A certificate of medical necessity (required by Medicare and many other insurance providers)

Stationary oxygen therapy systems

Stationary oxygen therapy systems come in two types: oxygen concentrators and liquid oxygen systems.

Oxygen concentrators

Stationary Oxygen Therapy system

These systems work by drawing in ambient air (called room air); separating out nitrogen and other room air components to leave 100% pure oxygen; passing the oxygen through the concentrator’s tubing; and then streaming it through the tubing to your nasal canula so that you can breathe the oxygen in.

Stationary oxygen concentrators are about the size of a bedside table and weigh between 20 and 70 pounds. These systems typically come with about 50 feet of tubing, so that’s how far you can move about your home while using the system. (If you need longer tubing, talk to your DME supplier.) These systems must be in a well-ventilated area of your home. They require regular maintenance by your DME supplier and filter changes to work well. Newer stationary oxygen concentrators produce enough oxygen that you can store it in a refillable tank to take with you in a backpack when you travel. Filling tanks yourself means that you don’t have to rely on your DME supplier to provide portable oxygen tanks.

  • Advantages. Newer oxygen concentrator models enable you to fill portable tanks from your stationary concentrator for easier mobility.
  • Disadvantages. Oxygen concentrators are large and require electricity, regular maintenance, and filter changes to work. If your power goes out, you’ll have to rely on your portable system for oxygen.

Neither Medicare nor insurance companies will reimburse you for the cost of the electricity needed to run your oxygen concentrator. You may be able to deduct the cost of electricity from your income tax, though. Check with your tax preparer for more information. Also, financial assistance may be available to help you with the cost of electricity. Check with your health care provider for information.

Liquid oxygen systems

Liquid oxygen system

When oxygen is cooled to low temperatures, it becomes a liquid. This liquid oxygen is then stored in metal tanks. When this liquid passes through the tubing to your nasal canula, it warms up and turns into a gas, which you then breathe in.

When oxygen is cooled to low temperatures, it becomes a liquid. This liquid oxygen is then stored in metal tanks. When this liquid passes through the tubing to your nasal canula, it warms up and turns into a gas, which you then breathe in.

Stationary liquid oxygen systems are large—up to 120 pounds. In fact, the main tank is too heavy to move, so if you have a summer home or will be away from home for a while, you’ll have to arrange for another home liquid oxygen system. How often your DME supplier must fill the main tanks depends on how much oxygen you use. Talk to your DME supplier about the length of tubing you need to move around your home easily and comfortably.

  • Advantages. Liquid oxygen systems are quiet (they have no moving parts) and don’t require electricity to work. Also, you can fill smaller, portable tanks from your main home tank.
  • Disadvantages. Liquid oxygen is not used often compared with oxygen concentrators. The home tank is large and must be secured so that it doesn’t tip over. Also, the main home tank has to be refilled regularly, which makes these systems more expensive to maintain. Some of the liquid oxygen in the system (approximately 1 pound daily) will evaporate naturally. As a result, home liquid oxygen isn’t available everywhere, so you’ll need to check with your DME supplier to make sure it’s available where you live or where you’ll be traveling.

Both oxygen concentrators and liquid oxygen systems are available as pulse-flow (also called demand-flow) systems and continuous-flow systems. Pulse-flow systems have a sensor that can tell when you inhale and deliver oxygen only when you breathe in. Continuous-flow systems provide oxygen constantly, even when you’re not breathing in. Your health care provider will prescribe the system that best meets your needs.

Portable oxygen therapy systems

Portable oxygen therapy systems come in three types: portable oxygen concentrators (POCs), portable compressed gas cylinders, and portable liquid oxygen.

Portable oxygen concentrators

Portable oxygen concentrator

POCs work the same way stationary concentrators do except that they run on batteries rather than electricity. POCs come in a variety of sizes, but note that the smaller the POC, the less oxygen it can produce and the shorter the battery life. Many POCs have a rechargeable battery that will last a few hours. If yours does not, be sure to keep extra batteries on hand for your system. Most POCs work by pulsed flow rate, which means that they deliver oxygen in a pulsed flow rate—that is, only when you inhale. If you need a POC with continuous flow, be aware that these POCs don’t go beyond 3 to 4 liters per minute. If you need continuous-flow oxygen therapy, your health care provider must specify that on the prescription.

There are many POCs on the market today. Some of the more commonly seen devices are made by Inogen, SimplyGo, and LifeChoice. The way a POC provides oxygen (pulsed flow, continuous flow, or both) and the oxygen flow rate it offers depends on the device and manufacturer. Work with your DME supplier to find the POC that’s best meets your needs.

There are many POCs on the market today. Some of the more commonly seen devices are made by Inogen, SimplyGo, and LifeChoice. The way a POC provides oxygen (pulsed flow, continuous flow, or both) and the oxygen flow rate it offers depends on the device and manufacturer. Work with your DME supplier to find the POC that’s best meets your needs.


POCs can be very expensive. As a result, not all DME suppliers offer them.

Most airlines allow POCs, but be sure to check with your airline before you travel with your POC. (See Traveling With Oxygen Therapy: Trip Planning Guide for more information about traveling with your oxygen therapy system.)

Portable compressed gas cylinders

Portable compressed gas cylinder

Portable compressed gas cylinders are available in many sizes, from some that weigh a few ounces and that you can carry in a backpack to those that weigh 8 pounds that you pull on a small cart. Some of these portable cylinders can provide oxygen continuously, but they will last just a few hours.


The higher the flow rate of oxygen, the faster you’ll use the oxygen stored in the cylinder.

If you have an oxygen conserver with your cylinder, the tank provides oxygen only when you breathe in. In this case, oxygen can be stored in the cylinder for up to 5 hours, depending on the size of the cylinder. You can fill these cylinders from your stationary oxygen concentrator. They make a good backup to a stationary oxygen concentrator if the power goes out, but they’re not designed for long-term use.


Use caution when handling these cylinders: They are under high pressure and can be extremely dangerous if they were to fall and crack a valve.

For information about Medicare reimbursement for portable oxygen therapy systems, please see Paying for Oxygen Therapy.

Portable liquid oxygen tanks

Portable liquid oxygen tank

Portable liquid oxygen is a less commonly prescribed oxygen therapy system, and many DME suppliers may not provide this option. However, the benefit of portable liquid oxygen is that it provides higher flow rates of continuous-flow or pulsed oxygen, is lightweight, and lasts longer than POCs or compressed gas cylinders. In addition, you can fill your portable liquid oxygen tanks from your larger stationary oxygen therapy system. These systems require no electricity to operate.

Other components for your oxygen therapy system

Besides the tanks or concentrators that store and supply your oxygen, you need some or all of the following accessories to use your oxygen therapy system:

oxygen therapy tubing

This thin hose connects from your stationary oxygen therapy system to your nasal canula or mask. Most stationary systems come with up to 50 feet of tubing.

If your health care provider has prescribed high-flow oxygen therapy (that is, you require more than 6 liters per minute of oxygen), your system will come with special high-flow tubing, which is slightly larger in diameter.

To clean your tubing, complete the following steps:

  1. Wash the tubing in warm, soapy water.
  2. Rinse the tubing in a solution of 10 parts water to 1 part vinegar to kill any bacteria.
  3. Rinse the tubing with hot water.
  4. Hang the tubing to dry.
oxygen therapy nasal canula

Nasal canula
This two-prong piece attaches to the tubing and goes into your nose to deliver oxygen.

 To clean your nasal canula, complete the following steps:

  1. Wash the canula in warm, soapy water.
  2. Rinse the canula in a solution of 10 parts water to 1 part vinegar to kill any bacteria.
  3. Rinse the canula with hot water.
  4. Hang the canula to dry.
oxygen therapy face mask

Face mask
If your health care provider has prescribed high-flow oxygen therapy, you may need to use a face mask instead of a nasal canula. This mask covers both your nose and your mouth and attaches to the tubing.

To clean your face mask, complete the following steps:

  1. Wash the face mask in warm, soapy water.
  2. Rinse the face mask in a solution of 10 parts water to 1 part vinegar to kill any bacteria.
  3. Rinse the face mask with hot water.
  4. Hang the face mask to dry.
oxygen therapy humidifier

A humidifier is a container filled with distilled water that attaches to the oxygen therapy system. The water mixes with your oxygen to help prevent it from drying out your nasal membranes.

To clean your humidifier, complete the following steps:

Wash the humidifier in warm, soapy water.
Rinse the humidifier in a solution of 10 parts water to 1 part vinegar to kill any bacteria.
Rinse the humidifier with hot water.
Set the humidifier aside to dry.

Note: POCs may not work with a humidifier.

Filters are small components that help keep the oxygen you breathe in clean and free from dust, bacteria, and other things that can make it hard for you to breathe. Which filters you need depends on your oxygen therapy system.

Safety tips for using your oxygen therapy system

To help you breathe and avoid lung and sinus infections, be sure to keep up with the following basics:

  • If you use an oxygen concentrator, change the filters regularly. Your DME supplier can help with this task and will supply the right filter for your oxygen therapy system.
  • Change your nasal canula, tubing, and face mask regularly.
  • If you use a humidifier with your oxygen therapy system, wash it at least once a week. Fill the humidifier with distilled water only.
  • Schedule a yearly maintenance appointment with your DME supplier for your stationary and portable oxygen therapy systems.

In addition, for as long as you have your oxygen therapy systems, follow these safety precautions:

  • Do not smoke or allow others to smoke around you (for example, in your home or car).
  • Avoid open flames, such as from candles, bonfires or fire places, cigarette lighters, pilot lights, and gas stoves.
  • If you use oxygen tanks, store them at least 10 feet away from any source of fire in a well-ventilated area out of direct sunlight.
  • Don’t use electric razors, hair dryers, and similar appliances that can cause sparks while you’re using oxygen.
  • Contact your DME immediately if you notice a crack in an oxygen tank. Don’t try to fix problems with your oxygen therapy system yourself.
  • Place a sign on the front door of your home to let visitors know that you use oxygen in your home.
  • Change the batteries in your smoke detectors every 6 months, and keep fire extinguishers in your home.
  • Let your power company and local fire department know that you have an oxygen therapy system in your home. Ask for your home to be a priority service listing.
  • Don’t use petroleum-based moisturizers on your face or chest (for example, Vaseline) or petroleum- or wax-based lip balm (for example, ChapStick).

Benefits of oxygen therapy

Oxygen therapy will help you breathe better so that you can maintain your lifestyle as much as possible. Once you start oxygen therapy, you may notice benefits such as:

  • Better quality of life
  • Less breathlessness and fatigue
  • Less stress on your internal organs, such as your heart
  • More energy
  • Better memory and sharper thinking

Remember, oxygen therapy can make you feel better than you did before it!

How will oxygen therapy affect my lifestyle?

There’s no question that you need to make some changes in your day-to-day routine when you have an oxygen therapy system. But, remember that oxygen therapy is there to help you breathe better, be more active, and live your life to the fullest.

Here are a few tips for making the most of life with your oxygen therapy system:

  • Be patient with yourself. Give yourself time to lean what you can do with your oxygen therapy system.
  • Make sure that your stationary oxygen therapy system comes with enough tubing so that you can move around your home easily.
  • If you’re planning to travel, be sure to read our Trip Planning Guide for information about traveling with an oxygen therapy system, including airline restrictions.
  • Get the support you need! Ask your health care provider about support groups in your area. Talking with other people who are on oxygen therapy can help tremendously. Also, the American Lung Association maintains a Support and Community page, or you can phone the Lung HelpLine at 1-800-LUNGUSA to learn more about programs, events, and resources.


CHEST Oxygen Toolkit

Our oxygen toolkit will improve your experience with oxygen therapy. Be among the first to know when it’s available.

CHEST Oxygen Toolkit
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Live your life to the fullest

A diagnosis of ILD can be a challenge, but you have the right to a happy and fulfilling life, whatever your diagnosis. Taking control of your treatment plan and seeking both physical and emotional support resources can help you regain some optimism. Remember, your support team should help you explore all available options to continue doing activities you enjoy and living a life full of the people and places you love.


The Erin Popovich Endowment, established with the CHEST Foundation, is changing what it means to live with ILD. The CHEST Foundation is the philanthropic arm of the American College of Chest Physicians.

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