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Oxygen Levels and Supplemental Oxygen.

Oxygen Levels and Supplemental Oxygen

When you have a chronic lung disease like COPD, doctors will often monitor your oxygen levels. If your oxygen levels are low, doctors may prescribe supplemental oxygen. So, what are oxygen levels, and what is supplemental oxygen? Here’s all you need to know.

What is oxygen saturation (SpO2)?

This is often referred to as the fifth vital sign, as it is often taken along with your other vitals: heart rate, respiratory rate, blood pressure, and temperature. It’s an estimate (and usually a very close estimate) of the percentage of oxygen you are inhaling that gets to your bloodstream. It is generally recorded as SpO2, which means peripheral oxygen saturation. A normal SpO2 is 98%, although greater than 90% is considered acceptable. In some special cases of severe COPD, your doctor may find that less than 90% is acceptable for you.

What is a pulse oximeter?

Most hospitals have these now as standard equipment. They are small devices that slip over a finger, toe, or earlobe. In fact, they have been around long enough now that they can be purchased at stores like Amazon or Walmart for as little as $20. They measure your oxygen saturation. You can talk to your doctor about whether you should have one at home, although some people who require oxygen find it nice knowing what their oxygen levels are, allowing them to increase or decrease their oxygen intake as necessary (of course, with permission from their doctors).

What is arterial blood gas (ABG)?

While most blood tests require venous blood, this test requires arterial blood, or freshly oxygenated blood. The best place to draw it is on the thumb side of the inside of your wrist where the radial artery is close to the surface. It is important because it measures your arterial gases: oxygen and carbon dioxide.

What is arterial oxygen saturation (SaO2)?

This is the same as SpO2 although it is considered to be accurate as it is measured directly from your arterial blood. Normal is 98%, although greater than 90% is considered acceptable.

What is partial pressure of arterial oxygen (P02)?

This is an accurate measurement of inhaled oxygen that gets inhaled into your blood. A level of 80-100 is considered normal. 60-80 is considered mild hypoxemia, or mildly low blood oxygen level. Anything greater than 60 is often considered acceptable.

Why is a pulse oximeter such a useful tool?

It’s nice because a 60 PO2 usually correlates well with an SpO2 and Sao2 of 90%, which explains why 90% saturation is generally considered acceptable. This is important because it allows you to measure your oxygen levels simply with a non-invasive pulse oximeter rather than having to undergo an invasive blood draw. So, this allows your doctor to conveniently check your oxygen levels in the office, or even for you to do so in the convenience of your own home.

Why is an ABG useful?

Chances are your doctor will want to obtain an accurate measure of your arterial oxygen levels just to make sure they correlate with your SpO2 reading. Likewise, an ABG can also provide your doctor with lots of other useful information such as I explain in my post, “What Is An ABG?”

What is supplemental oxygen?

It is when your lungs require more oxygen than what is provided to you in room air to oxygenate your blood. Room air contains about 21% oxygen, so supplemental oxygen would entail inhaling anywhere from 21% to 100% oxygen.

What devices supply supplemental oxygen?

The most common device used to provide it to you is a nasal cannula. This is a lightweight and easy to tolerate plastic device with prongs that enter your nares. A low flow enters your nose and your lungs along with oxygen in room air. Usually, this provides your lungs with all the supplemental oxygen needed to adequately maintain healthy and normal oxygen levels in your arterial blood.

When is supplemental oxygen needed?

Supplemental oxygen is usually indicated when your oxygen saturations are consistently less than 90% or your PO2 is less than 60. Medicaid will only pay for supplemental oxygen if you qualify. Their qualification requires that a caregiver measuring your oxygen saturation while you’re walking. If it drops below 88% you qualify.

What happens if I qualify for supplemental oxygen?

Your doctor’s office will set you up with an appointment by the home health care provider of your choice. This person will bring all the equipment you need to your home and teach you how to use it. You will probably use an oxygen concentrator, which is a small machine that turns room air into pure oxygen for you to inhale. You will hook up your nasal cannula to this concentrator. Your provider will probably also provide you with some oxygen tanks to use for when you leave your home. Oxygen tanks also work nice should the electricity go out and your concentrator stop working.


Low oxygen levels due to COPD may cause you to feel short of breath. Supplemental oxygen can help you breathe easier, and it’s also proven to help you live better and longer with COPD. So, with a diagnosis of COPD, your doctor will want to monitor your oxygen levels so supplemental oxygen can be prescribed when needed.

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.


  • Leo4u
    9 months ago

    COPD since 2013,
    Part of enquiry to my Hospital.
    I’m fully aware that my Oxygen Blood levels are above 90% when tested within a calm relaxed environment, nevertheless you would be fully aware by now that I have suffered from COPD for many years, the recent relapse and Hospitalisation on the 16/02/2019 until 22/05/2019 was due to Lung infections, which we could have easily treated at home with my emergency medications pack and supplemental Oxygen if it had been issued.

    I used those emergency medications since leaving Hospital on 22/02/2019 and they cleared up a nasty Lung infection, which I informed Respiratory Medicine Department Doctor of, on the 3rd May 2019.
    A Supplemental, Oxygen supply at home would have greatly helped in both of these relapses?

    Best regards,

  • Leon Lebowitz, BA, RRT moderator
    9 months ago

    Hi Leo4u and thanks for joining in the conversation here based on the article about oxygen levels and supplemental oxygen. We appreciate you sharing the letter you wrote to the hospital. Based on this recent experience (successfully managing your condition at home with the medication that you have been dispensed), are you able to continue doing that? Are you working closely with your physician? What is their view of your planned strategy to provide self care? Leon (site moderator)

  • buckybuck
    3 years ago

    I appreciate your easy to understand explanations, John. I am very thankful for the concentrators and the portable tanks. I also have a portable concentrator that I consider for emergencies because it is heavy. Anything lighter would have only lasted less than 3 hours on battery. And it was expensive, but at least I know it’s there if needed. My biggest problem is with my supplier. They want to limit the portable tanks to a point that I find I am rationing myself too much. Does Medicare really limit the suppliers as they have indicated?

  • lynn2u
    3 years ago

    Thanks John for this article and its non-alarmist tone. Also, I want to add that while I opted for medicare to provide the tank and tank refill system, I purchased a tiny portable unit that I just adore! My insurance covered either or and so I let them provide the tanks etc and I gave up a cruise I did not want anyway to buy my own InogenOne G4. 17 years ago when my husband was being treated for COPD, these little guys weren’t even an option. We’ve come a long way baby.

  • John Bottrell, RRT moderator author
    3 years ago

    Hi. Lynn. And You are welcome. After I wrote this one of my patients was telling me about the portable oxygen concentrator. It’s pretty remarkable, as you note, how far technology has come in such a short time. The next goal is to get that price down, as I Googled it and saw the price. Thanks for your comment. John.

  • JoanneC
    3 years ago

    While I agree with what you’ve written about Medicaid being unwilling to provide supplemental oxygen until you’re at 88% oxsat, my Better Breather’s Club indicates that degradation of other bodily functions / organs begins at 92% and not 90% as you’ve seemed to indicate.

    Do you have any explanation as to the 2% difference?

    Clearly, we’re all dealing with multiple health challenges once our pulmonary system is involved. If we push oxygen deprivation below the recommended standards of the American Lung Association / Better Breather’s Clubs, what does it do to the reliability of our cognitive abilities, our overall levels of exhaustion, etc?

    I’d be very interested in your data source for the 90% reference point. otherwise, I found this to be an interesting article.

    If you wish to write about “hardening” of the lungs due to mis-use of oxygen, that would be appreciated, too.

  • John Bottrell, RRT moderator author
    3 years ago

    Hi. Joanne C. I can try to answer your question about the 2% difference. In most people, a normal PO2 is 80-100, with greater than 60 considered acceptable. Less than 60 and your doctor will probably start thinking supplemental oxygen to assure your blood and tissues are receiving enough oxygen. As noted in the article, an SpO2 of 90% correlates well with a PO2 of 90. Back when I started as an RT 20 years ago, we wanted to keep patients at 92% or better. This was basically to play it safe. Today, we use 90%. Medicare uses 88%. For instance, you must have a walking SpO2 of 88% or less to qualify for home oxygen. To put it another way, the generally accepted range of SpO2 for most COPD patients is 88-92%. Medicare tends to recommend the low end (because they don’t want to pay), and healthcare institutions (like hospitals) usually recommend 90% or better to be on the safe side. Yet another way of looking at it (and maybe this would have been an easier answer for you, is that pulse oximeters are usually considered accurate +/-2%. So, I hope this answers your questions. If not, please feel free to come back at me with another question. Thanks. John.

  • lynn2u
    2 years ago

    Thank you John. As always your comments are always clean, clear and enlightening.

  • KevinDavitt moderator
    3 years ago

    Nice article, John.

  • John Bottrell, RRT moderator author
    3 years ago

    You are welcome! And thank YOU!!!

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