The Need for Supplemental Oxygen

The amount of oxygen in the bloodstream can be easily measured two ways: 

  • Oximetry — This is the method used most often. A small, clip-on device shines a light through your finger or earlobe and measures the amount of light absorbed by the oxygen-carrying hemoglobin in the red blood cells. By calculating the amount of light absorption, the device can measure how saturated the hemoglobin is with oxygen molecules, or O2 sat. Normally, the oxygen saturation of the blood is around 98 to 100 percent.
  • Arterial blood gas study — In this procedure, blood is drawn out of an artery, usually in the wrist, using a needle and syringe. The blood is then sent through an analyzer to measure the amount of oxygen gas dissolved in the blood. This result is called the arterial oxygen pressure (paO2), and is normally 80 to 100 mm Hg.

The body needs enough oxygen to keep the blood adequately saturated, so that cells and tissues get enough oxygen to function properly. Furthermore, cells and tissues can neither "save up" nor "catch up" on oxygen — they need a constant supply. When the oxygen saturation falls below 89 percent, or the arterial oxygen pressure falls below 60 mmHg — whether during rest, activity, sleep or at altitude — then supplemental oxygen is needed. 

Your health care provider can determine your supplemental oxygen needs by testing you while you are at rest and while walking, and can also order an overnight oximetry study to test your oxygen saturation at night. . A high altitude simulation test is also available to test your oxygen saturation at 8000 ft (the cabin pressure of most airliners).

When and how often do I have to wear my oxygen?

Your health care provider will write a prescription for when and how much you should wear your oxygen, based on the results of your testing. The prescription should specify the following: 

  • The appropriate oxygen flow rate or setting, expressed as liter flow of oxygen per minute (lpm or l/min) that will keep your saturations at or above 90 percent
  • When you should wear your oxygen (for instance, during activity, overnight or continuously)
  • The type of equipment that will accommodate your lifestyle needs

Why would I need to wear oxygen while sleeping?

Everyone's oxygen levels in the blood are lower during sleep, due to a mildly reduced level of breathing. Also, some alveoli drop out of use during sleep. 

If your waking oxygen saturation is greater than about 94 percent on room air, it is unlikely that your saturation during sleep will fall below 88 percent. However, your doctor can order an overnight oximetry test if there is a question about your oxygen saturation levels while you are sleeping. 

How do I know that I'm using the right amount of supplemental oxygen?

To determine if you're getting the right amount of supplemental oxygen, your oxygen saturation must be measured while you are using your oxygen. Your provider or a respiratory therapist from the oxygen supplier should test your oxygen saturation on oxygen while you are at rest, while walking and, if indicated, while you are asleep. As long as your saturation is in the 90s, you are getting the right amount of supplemental oxygen. 

Should I buy my own finger oximeter to test my oxygen saturations?

It is probably a good idea to buy a finger oximeter, so that you are sure you are getting the right amount of supplemental oxygen. Finger oximeters are available on the internet, through medical supply companies and even in sporting goods stores. 

How will using supplemental oxygen benefit me?

When a person isn't getting enough oxygen, all organs of the body can be affected, especially the brain, heart and kidneys. Wearing supplemental oxygen keeps these organs, and many others, healthy. There is evidence that, for people who are hypoxemic, supplemental oxygen improves quality of life, exercise tolerance and even survival. 

Supplemental oxygen can also help relieve your symptoms. You may feel relief from shortness of breath, fatigue, dizziness and depression. You may be more alert, sleep better and be in a better mood. You may be able to do more activities such as traveling, including traveling to high altitudes. 

Symptoms such as shortness of breath may be caused by something other than lack of oxygen. In these cases, supplemental oxygen may not relieve the symptom. But if tests show you are not getting enough oxygen, it is still important to wear your oxygen. 

Does my need for supplemental oxygen mean that I don't have long to live?

People live for years using supplemental oxygen. 

Will I always need to use supplemental oxygen?

That depends on the reason oxygen was prescribed. If your lung or heart condition improves, and your blood oxygen levels return to normal ranges without supplemental oxygen, then you don't need it anymore. 

Can I become "dependent on" or "addicted to" oxygen?

There is no such thing as becoming "dependent on" or "addicted to" supplemental oxygen — everybody needs a constant supply of oxygen to live. If there is not enough oxygen in your bloodstream to supply your tissues and cells, then you need supplemental oxygen to keep your organs and tissues healthy. 

Does supplemental oxygen cause side effects?

It is important to wear your oxygen as your provider ordered it. If you start to experience headaches, confusion or increased sleepiness after you start using supplemental oxygen, you might be getting too much. 

Oxygen settings of 4 liters per minute or above can cause dryness and bleeding of the lining of the nose. A humidifier attached to your oxygen equipment or certain ointments can help prevent or treat the dryness. For more information, see "Higher Oxygen Flows" in Your Oxygen Equipment

Will I be able to go out and about with my oxygen equipment?

The goal is to have you continue as many of your usual activities as you can. You should work with your health care provider and oxygen supply company to get oxygen equipment that will allow you to do these things. Choosing the right type of equipment for you and your lifestyle is very important — the right ambulatory oxygen equipment can play a major role in improving the quality of life.

Your Oxygen Equipment

How do I choose the right oxygen equipment for me?

You, your health care provider and your oxygen supplier should all work together to choose the oxygen system that is right for you — one that takes into account your lifestyle and activities, as well as the amount of oxygen you need. The goal is to have oxygen equipment that you can and will wear, so you can keep enjoying your usual activities.

Some of the factors to consider when choosing your system and equipment are listed below: 

  • The amount of oxygen your doctor has prescribed for you (written as liter flow of oxygen per minute, such as 2 liters/min)
  • How often and for how long you leave your house
  • What activities you do while you are out
  • Your size, strength and endurance versus the weight of the equipment
  • The size and layout of your home (for instance, whether your house has two or more stories)
  • Whether you breathe through your nose or your mouth
  • Your dexterity
  • Your personal preferences

What type of equipment is available?

The three types of oxygen systems currently available are:

  • Compressed gas systems
  • Portable oxygen concentrators (POCs)
  • Liquid oxygen systems

The compressed gas system consists of a stationary concentrator, to be used in the home, and a small oxygen tank, to be used outside the home. The liquid oxygen system consists of a stationary concentrator or reservoir to use while you are in your home and an ambulatory tank to use when you go out. The portable oxygen concentrator can serve as both the ambulatory device and the stationary concentrator in certain circumstances. 

Type of System Ambulatory Component Stationary Component
Compressed gas system Small, pre-filled tanks delivered to you on a weekly basis, depending on how much oxygen you are using, or tanks that fill overnight at home (aka a home-fill system) from your concentrator. 

These small tanks must be used in conjunction with an oxygen conserving device or regulator (OCD) that delivers the oxygen in pulses, so that the oxygen supply lasts longer. 

Oxygen concentrator with 50-foot tubing
Liquid oxygen system Small, refillable tank that you fill from the reservoir as needed Oxygen reservoir with 50-foot tubing
Portable oxygen concentrator (POC) A small electric device that can be worn on the back or wheeled around, runs on regular electricity or a battery, is easily recharged even in a car, and requires no tanks or filling. The maximum tubing length for proper delivery of oxygen is 7 feet. These units can be taken onto airplanes.  

Ambulatory Versus Portable Oxygen Equipment

While the terms portable and ambulatory oxygen equipment are often used interchangeably, there is an important difference. In 1999, the 5th Oxygen Consensus Conference differentiated between portable and ambulatory oxygen systems. 

Portables are defined as easily moved devices that are not designed to be carried and weigh more than 10 pounds. Ambulatory devices are defined as weighing less than 10 pounds, available for daily use, designed to be carried by the patient, and lasting four to six hours at a setting of 2 liters per minute. They are normally small aluminum cylinders or liquid oxygen containers equipped with oxygen conserving devices (OCDs). 

E-tanks are the larger, older metal tanks that are wheeled around. They can be the right choice for some people and situations, but are generally not considered to be ambulatory devices. They are often used as back-up systems in the home, should the electric power in the home fail. 

Oxygen Conserving Device (OCD)

The oxygen conserving device (OCD) is the device on your small compressed gas tank that makes the oxygen supply last longer. It causes the oxygen to be delivered only when you take a breath. Not all OCDs deliver the same amount of oxygen as a continuous flow would, so it is important that your oxygen saturation be tested at rest and with activity while you are using the OCD, to make sure you are getting enough oxygen. 


Several accessories come with your oxygen equipment. In addition, there are other accessories to make wearing or carrying your oxygen more comfortable. Below are examples of a few basic accessories. 

Example of a portable oxygen concentrator (POC)
  • Nasal cannula — Oxygen is generally delivered through tubing and a nasal cannula, sometimes called nasal prongs. The nasal cannula end of the tubing fits into your nose, and is the most common delivery accessory. The stationary equipment for home use comes with 50-foot tubing, so you can freely move about the house. The ambulatory equipment comes with shorter tubing.
  • Oxygen masks — Oxygen masks can also be used for higher oxygen needs. The Oxymask is a comfortable version.
  • Oxygen conserving device — An Oxymizer mustache or pendant can increase the amount of oxygen delivered or make the oxygen last longer.
  • Humidifier bottle — Higher oxygen settings can be drying to the lining of the nose. A humidifier attached to your stationary oxygen equipment can help prevent this dryness.
  • Carrying cases, carts — Ambulatory oxygen tanks can be rolled in small carts, carried in backpacks and sometimes even worn as a waist pack. Portable oxygen concentrators are rolled in their own cases, worn in a backpack on the back or slung over the shoulder.
  • Oxyview glasses: Using supplemental oxygen is a big lifestyle change. Patients on oxygen can have low self-esteem and feel socially isolated. Oxyview glasses are designed to make the use of supplemental oxygen less visible. More information can be found here.

Increased Oxygen Needs and Higher Oxygen Flows

Rates of 4 liters/minute or greater are considered higher oxygen flow. As more scarring develops in the lungs, they become less efficient in delivering the necessary oxygen the body needs. If you need more than 5 Liters/min of supplemental oxygen, you should discuss with your healthcare provider about other oxygen delivery systems such as a high flow concentrator for oxygen needs beyond 6 Liters/min. You may need humidification with higher flows of oxygen to prevent dryness of your nasal passages. You may want to consider switching from a portable oxygen concentrator to compressed gas tanks which, although cumbersome, allow for continuous oxygen delivery which may make you feel less short of breath and more comfortable. Devices such as oxymizer reservoirs (pendants or mustaches) can replace nasal cannula to allow for oxygen tanks to last longer when outside of the home. In short, it's important to have the appropriate equipment to prevent adverse effects associated with low oxygen and to keep you as active with your family and friends as possible.  

  • Liquid systems deliver higher flows of oxygen for longer periods of time. Unfortunately, it is getting more difficult to obtain liquid oxygen systems.
  • Oxygen conserving devices may not deliver enough oxygen. Continuous flows are better for flow rates above 4 liters/minute. 
  • There are high-flow stationary concentrators that go up to 10 and 15 liters/minute. 
  • For oxygen settings higher than 6 liters/minute, a high flow nasal cannula is needed. 
  • Certain oxygen face masks and reservoir cannulas can boost the delivery of oxygen and make high oxygen flows more comfortable. 
  • For irritated nasal passages due to high flow oxygen, try RoEzIt or ocean nasal spray. Do not use petroleum based gels or ointments like Vaseline. For more info on nasal care, see these tips by UCSF respiratory care therapist, Julia Rigler. (Link PDF here).
  • Due to the increase in back pressure and resistance to flow, disposable humidifier bottles are not recommended for flows greater than 6 liters/min. 

Where do I get my oxygen and equipment?

Your provider can help you choose an oxygen company, or you may choose any company you want. Some insurance policies dictate which oxygen company you must use. 

Who will pay for my oxygen and equipment?

Most insurance policies cover supplemental oxygen when the medical necessity for oxygen is demonstrated. This necessity is based on the oxygen saturation or the arterial blood gas measurements. 

Generally, if your O2 saturation falls below 89 percent, or your paO2 falls below 60 mm Hg — whether at rest, with activity or during sleep — then you qualify for supplemental oxygen. For more information, see The Need for Supplemental Oxygen

You may find that your electric bill increases after you receive an oxygen prescription. We encourage you to call your electricity provider (PG&E if you live in California) to inquire about available assistance programs for those with medical conditions such as receiving extra notifications in advance of a Public Safety Power Shutoff or lowering the rates of your monthly energy bill. Please also refer to our Environment and ILD section of this website (listed under "Living Well With ILD") for emergency preparedness tips.  

Oxygen is an IRS-approved medical expense. Also, the cost of electricity used to operate your oxygen concentrator may be deductible. See IRS publication 502, Medical and Dental Expenses.

How do I maintain my equipment? 

Your oxygen supply company will give you instructions for cleaning your equipment. Some basics are listed below: 

  • The nasal cannula should be changed every week.
  • The long tubing attached to your stationary equipment should be changed according to the guidelines supplied from your oxygen company. 
  • If an oxygen face mask is used, it should be cleaned twice weekly with warm soapy water and allowed to air dry completely before using.
  • Oxygen concentrators usually require a weekly filter cleaning with warm soapy water and allowed to air dry completely before using.
  • If you are using a humidifier, empty it at least once a day, wash the bottle with soap and warm water, making sure all the soap is rinsed out, and then refill the bottle with distilled water. Do not use tap water, as the minerals in it can damage your equipment.