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Patient Resources

Oxygen Therapy

Oxygen Therapy

Oxygen Therapy

Some adults and children may need extra (supplemental) oxygen. While lung conditions are the most common reason for needing supplemental oxygen, other conditions that affect the heart or sleep may also require treatment with oxygen.

Why do I need oxygen?

We need oxygen for the cells in our body to function properly. The air we breathe contains about 21% oxygen, which is plenty for people with healthy lungs.  However, your lung condition may prevent you from getting enough oxygen from your lungs into your blood. If your oxygen level is low, your healthcare provider will recommend supplemental oxygen. Sometimes you only need extra oxygen in certain situations. For example, you may only need to use oxygen with activity and not when sitting quietly.

How do I know I need oxygen?

Some people may notice worsening shortness of breath, or rapid heartbeat, but other people do not know when they need oxygen. Your healthcare provider will check the amount of oxygen in your blood with either a blood sample or an oximeter. A blood sample is drawn from an artery (usually in your wrist) for an arterial blood gas (ABG) measurement. The ABG measures your oxygen (and carbon dioxide) levels directly from your blood and is the most accurate of the tests. This can be done in the office, clinic or hospital, wherever the arterial blood test equipment is available. A pulse oximeter can estimate your oxygen level by measuring your oxygen saturation (O2 sat). The pulse oximeter is clipped on a finger, toe or earlobe and has the advantage of not requiring any needles. It can also monitor your oxygen during sleep or with walking. However, the pulse oximeter does not provide as much information as an ABG. Oximeters also can give an inaccurate reading if your circulation is poor (cold hands), you are dark skinned, wearing dark nail polish, or if you are anemic.

How much oxygen should I use?

Oxygen is a medication and requires a prescription from your healthcare provider. They will prescribe your oxygen at a specific flow rate to use at rest, during activity, and during sleep. Some patients will be prescribed oxygen 24 hrs./day, or most of the day. If your oxygen level is lower during activity than at rest, you may have one

 flow rate prescribed for rest and a higher flow rate prescribed during activity. Use your oxygen as prescribed; too little oxygen may put a strain on your heart and brain, causing heart failure, fatigue or memory loss, while too much can cause some patients to slow their breathing to dangerously low levels.

Will I need oxygen when I sleep?

If you use supplemental oxygen during the day, you may need to use oxygen at night. The reason is that we tend to slow our breathing rate while sleeping. Some people may not require oxygen while awake but may need supplemental oxygen only while sleeping. Your healthcare provider may refer you to a sleep specialist to evaluate your need for oxygen during sleep.

How do I know if I need more oxygen when I exert myself?

Your need for oxygen increases during exertion and therefore, need more oxygen than at rest. With some lung conditions, even breathing faster or deeper may not be enough to get oxygen into your blood. Your healthcare provider may therefore have you do an exercise stress test or a walk test to find out if your oxygen levels drop with walking. In children, the amount of oxygen they need can be determined by measuring their oxygen level during play and with feedings.

How many hours a day will I need oxygen?

If your oxygen levels are low when at rest, you should ideally use supplemental oxygen for 24 hours a day, otherwise you should use it as prescribed- for example only with activity. Even if you feel “fine” off of your oxygen, your body’s oxygen level may be low which can put you at risk for brain and heart problems.

Will I always need to use oxygen?

Sometimes you may only need oxygen during or after a short illness. If your lung condition and oxygen level improve, oxygen therapy may be reduced or stopped. However, you should never stop or cut back your oxygen without being instructed to do so by your healthcare provider.

What are the different kinds of oxygen systems?

Oxygen can be delivered from three types of systems: oxygen concentrator, liquid system or oxygen pressurized in a metal cylinder. The right choice for you depends on how much oxygen you need (your flow rate) and when you need it (day, night or both). Portable oxygen devices that you can use outside of the home vary in how much oxygen they deliver and whether it is delivered using continuous flow, or as a ‘pulse dose’. It is important to review your options carefully with someone knowledgeable about oxygen devices, such as the office nurse, a respiratory therapist, or someone at the oxygen supply company.  The choice of delivery system also depends on what your local supply company offers, how active you are outside of the home, cost to you and insurance restrictions. It is very important that you receive education and training on how to use the equipment that you receive. 

What are oxygen concentrators?

An oxygen concentrator is a device that takes in the oxygen we normally breathe (that consists of 21% oxygen), removes other gases from the air and delivers 85-95% pure oxygen. The concentrator runs on electricity or a battery. A concentrator for home usually weigh about 30-50 lbs (14–23 kg) and is usually on wheels so that it can be moved from room to room.
Portable oxygen concentrators weigh about 3-20 pounds (1-9 kg), depending on the battery weight and thus, are more convenient to use. However, portable concentrators may deliver a lower percentage of pure oxygen than a larger home concentrator. Also, some portable devices deliver a “pulse” of oxygen rather than a continuous flow. Before purchasing or renting a portable oxygen concentrator, ask your healthcare provider to measure your oxygen level while using the portable concentrator while you are at rest and while being active, to make sure that the system can deliver enough oxygen to you.

What is liquid oxygen?

Liquid oxygen is made by super-cooling (-300 degrees) oxygen. When in liquid form, oxygen takes up less space, so one can store a large amount in the home in thermos-like storage canisters. Liquid systems deliver 100% oxygen, and do not require electricity. A small canister can be filled from the large one for portability. This small canister weighs about 11 pounds (5 Kg) and can be carried or placed in a cart.

What are oxygen cylinders?

Oxygen is compressed under high pressure into a metal cylinder and is stored in either large or small cylinders. This is the oldest method for storing oxygen. Cylinders contain 100% oxygen. Large cylinders are not portable and often used as the primary source of oxygen in the home. However, using a large tank in your home can require frequent replacement and can be expensive. You may be able to use an oxygen concentrator instead as the primary source of oxygen. Smaller cylinders are used as portable oxygen when leaving the house. Small cylinders (E- cylinders) weigh about 8 lb (3-4 Kg) can be put in a cart. A smaller “D” cylinder weighs 5-6 lbs (2.5 Kg) can be carried in a backpack.  The E cylinder can serve as a backup during a power outage or equipment issue.

What is a nasal cannula?

A nasal cannula is a two-pronged tube that is placed in your nose for delivering oxygen. The other end of the tube is attached to your oxygen system. A nasal cannula has the ability to deliver high amounts of oxygen. However, high-flow oxygen (greater than 4 liters/minute) delivered by a nasal cannula can dry your nasal passages. This drying can sometimes be reduced with a humidifying device to warm and moisten the oxygen.

What is a pulse (on-demand) device?

A pulse oxygen delivery device delivers oxygen when you breathe in. As you breathe in, some devices sense the start of your inhalation and immediately gives a short “pulse” of oxygen. Other devices provide a regular pulse of oxygen at preset intervals. Pulse systems can help you preserve so your oxygen lasts longer. Young children and adults who are weak or do not inhale strongly may not trigger the sensor when they inhale, and hence, will not get enough oxygen. These individuals should not use a pulse (on-demand) device. Oxygen concentrators, liquid oxygen systems and small cylinders all have the ability to provide ‘pulsed’ oxygen. You should confirm with your healthcare provider that you are getting enough oxygen through a pulse device before buying or renting it.

Do I have to worry about oxygen exploding or burning?

Oxygen alone will not “explode” and does not burn. Oxygen will make a flame burn hotter and brighter. You should never smoke while using oxygen. Your nose, hair, and clothing can catch fire very quickly and cause life-threatening burns. Keep oxygen at least 6 feet (2 meters) away from any open flame. If a cylinder falls and cracks, it propels like a torpedo. Stabilize all cylinders by placing in a safe area or by chaining them to a wall.

What do I need to do when I travel?

Talk with your healthcare provider to see if you will need oxygen on an airplane. If so, contact the airline customer service department to find out their rules for using personal oxygen concentrators (POC) on the plane. You may be required to select a window seat, and you will need to have enough battery power for your POC during the flight. You should also contact your medical supply company for POC rentals and help with travel needs throughout the trip, including to the airport, while waiting at the airport, during stopovers, and at your travel destination.

Rx Action Steps

Use your oxygen as prescribed by your healthcare provider.

  • Discuss with your healthcare provider what options you have for oxygen delivery systems and which works best for your activity level.
  • Have your oxygen level checked at rest and with activity when using your oxygen delivery system.
  • Do not smoke, especially around any oxygen devices.
  • Avoid being around open flames and people who smoke when using oxygen.
  • If you are traveling, plan ahead to ensure you have enough oxygen at every step of your trip.

Additional Resources

American Thoracic Society

American Lung Association

COPD Foundation

Pulmonary Fibrosis Foundation


No Person Left Behind

Authors: Suzanne C. Lareau RN, MS, Bonnie Fahy RN, MN
Reviewers: Hrishikesh S Kulkarni, MD, Marianna M Sockrider MD, DrPH, Jennifer Hayes (degree), Trina Limberg (degree)
Illustration credit: OurDesigns, Inc.

This information is a public service of the American Thoracic Society. The content is for educational purposes only. It should not be used as a substitute for the medical advice of one’s health care provider.

Am J Respir Crit Care Med Vol 171, P1-P2, 2005
Online version updated February 2024
ATS Patient Education Series © 2016 American Thoracic Society


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