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Getting to Know Blood Oxygen Levels

blood oxygen levels

Understanding your oxygen levels is helpful to understanding how your body functions, but it is especially important for people living with breathing difficulties. If you struggle with breathing problems or heart problems, you may experience low blood oxygen levels, which can be dangerous if left untreated. 

If you need to know whether your oxygen levels are healthy, it is essential that you understand what a normal blood oxygen level is for you, as well as how to regulate your blood oxygen level when it gets low. Read on to learn more about blood oxygen levels and how to tell if you should be concerned about yours.

What Is a Blood Oxygen Level?

When you measure your blood oxygen level, you are measuring how much oxygen your red blood cells are carrying at the time the measurement is taken. Because every cell in your body requires oxygen to function properly, maintaining a normal blood oxygen level is essential to your health. If you struggle with breathing problems or heart problems, it is likely that your health care team will want to carefully monitor your blood oxygen level to ensure that your body is getting the oxygen it needs. If your blood oxygen level is below normal, which is called hypoxemia, you will need to treat the condition quickly.[1,3,4]

How Is Your Blood Oxygen Level Measured?

In order to understand your blood oxygen level, you should first understand how blood oxygen levels are measured. Both the arterial blood gas study and pulse oximetry can be used to measure your blood oxygen level. Pulse oximetry is most common as it is noninvasive, but the tests work differently, so depending on your health concerns, your doctor may opt to use one or both tests.[1,3,4]

  • Arterial blood gas (ABG) study: An arterial blood gas study is a blood test used to measure the oxygen and carbon dioxide levels in your blood, as well as the acidity, or pH, of your blood. This test is able to tell medical professionals how well your lungs are functioning and whether they are effectively allowing oxygen to be absorbed into your blood while removing carbon dioxide the way they should. An ABG test is conducted by drawing blood from an artery, where the blood is oxygenated. Be aware that arteries are located deeper than veins, so drawing blood from an artery is more uncomfortable than a typical blood draw from a vein. The measurements gathered from an ABG test are able to provide a great deal of helpful information to your doctors in just 15 minutes. A normal blood oxygen level (sometimes called a PaO2) should fall between 75 and 100 mm Hg (or millimeters of mercury).
    Blood sample tube for arterial blood gas test

    Arterial Blood Gas Study

  • Oximetry: Oximetry is a noninvasive way to test a patient’s blood oxygen level. You are likely familiar with the pulse oximeter that is placed on your fingertip, though it can also be placed on your toe or earlobe. A pulse oximeter sends two light frequencies (infrared and red) into the capillaries in your finger, toe or earlobe and determines the oxygen saturation level in the hemoglobin in your blood by measuring how much light is reflected off the gases. A pulse ox measurement is less accurate than an ABG measurement, with a 2% margin of error according to the American Thoracic Society, so your health care team may use a pulse oximeter as a jumping off point, but follow with an ABS test if the results are concerning. A normal blood oxygen level as measured by a pulse oximeter (also called your SpO2 level) generally falls between 95 and 100 percent.
    pulse oximeter

    Pulse Oximeter

How to Identify Whether Your Blood Oxygen Level Is Healthy or Unhealthy

It is important to know what your personal normal blood oxygen level is, and your doctor will be able to identify what is normal for you after doing a thorough examination and running your blood oxygen level tests. However, unless your doctor tells you to expect something different as a result of COPD or another health condition that could cause a lower than normal blood oxygen level, there are some general guidelines you should follow.

When it comes to your ABG oxygen level (PaO2), the normal reading is between 80 and 100 mm Hg. A normal pulse ox measurement (SpO2) should be between 95 and 100 percent. If your blood oxygen levels are falling below 75 mm Hg or below 90 percent, you should be taking measures to improve your blood oxygen level right away. 

pulse oximeter

What to Expect If Your Blood Oxygen Level Is Below Normal

Having a low blood oxygen level (hypoxemia) can present a number of problems. Symptoms can include a blue tint to the lips, skin or fingernails, chest pains, confusion, coughing, disorientation, headache, rapid heartbeat, shortness of breath and wheezing.[1,3] Many of these signs of hypoxemia can also be symptoms of COPD and other pulmonary issues, so it is essential that if you struggle with breathing or heart problems, you pay close attention to your symptoms. Any increase may mean that you are not getting sufficient oxygen. 

The blue tint to lips, nails and skin, also known as cyanosis, is a sign that hypoxemia has continued for too long. If you see this blue discoloration, it is critical that you seek immediate medical attention to ensure that your body is not without sufficient oxygen for too long. A lack of oxygen is life-threatening, and if you continue without the oxygen you need, you could suffer respiratory failure, fall into a coma or even die.[1,3]

How to Treat Low Blood Oxygen Levels

If your doctor finds that you have hypoxemia or suffer from a consistently low blood oxygen level, they will likely prescribe supplemental oxygen. Because medical oxygen is concentrated and you breathe it directly through a mask or nasal cannula, oxygen therapy allows your body to breathe in and absorb a much higher percentage of oxygen than is in the air around you, which quickly helps improve your blood oxygen level. Depending on when and why you are experiencing low blood oxygen, your doctor will prescribe oxygen therapy to provide the oxygen you need at the times you need it most.

The times at which patients experience hypoxemia can vary quite a bit, depending on the cause. Some people’s oxygen levels only drop at night, as with sleep apnea, while others experience low blood oxygen during times of exertion. Thankfully, no matter when you experience a low blood oxygen level, supplemental oxygen is a highly effective treatment.

Your doctor will first do a number of tests to clarify the cause of your hypoxemia and to ascertain your normal blood oxygen level. Once oxygen therapy has been prescribed, they will likely test, or teach you how to test, your blood oxygen level with a pulse oximeter during and after oxygen therapy to see if your supplemental oxygen prescription is sufficient to treat your hypoxemia. In many cases, the prescription is just right from the start, but some prescriptions will need adjustments. Regardless of your pulse ox reading, however, do not adjust your oxygen flow rate or the amount of time you are using supplemental oxygen without first speaking with your doctor. If you feel your oxygen prescription is not providing enough oxygen to maintain a normal blood oxygen level or to provide relief from your systems, talk to your doctor as soon as possible about any adjustments that may need to be made to your prescription.[3]

A Portable Oxygen Concentrator Can Help Treat Low Blood Oxygen Levels

If you have a consistently low blood oxygen level and have been prescribed supplemental oxygen, talk to your doctor about whether a portable oxygen concentrator (POC) is right for your oxygen therapy. Portable oxygen concentrators can provide the supplemental oxygen you need without requiring that you be tethered to a heavy metal tank. With the versatility of a POC, like those made by Inogen, you can continue participating in your daily activities while still receiving medical oxygen. Inogen’s portable oxygen concentrators allow you to regulate your blood oxygen level and get relief from your low blood oxygen symptoms by providing your supplemental oxygen anytime you need it throughout the day (as long as you are connected to a power source or fully charged battery), while still allowing you to maintain the freedom, independence and mobility you want. 

At Inogen, we know how critical it is to your health to maintain a normal blood oxygen level, but we also believe that supplemental oxygen should work with your life. Our small, lightweight POCs allow you to live as full and active a lifestyle as possible, allowing you to get your supplemental oxygen whether you are traveling, out and about or enjoying the comfort of your own home. Find out how the right prescription from your doctor and a portable oxygen concentrator from Inogen can help you maintain a normal blood oxygen level today. Talk to your doctor about which POC might be right for your oxygen needs, and contact us with any questions. Breathe better and keep your blood oxygen at healthy levels with Inogen.


  1. https://www.healthline.com/health/normal-blood-oxygen-level
  2. https://www.webmd.com/lung/arterial-blood-gas-test#1
  3. https://www.medicinenet.com/hypoxia_and_hypoxemia/article.htm
  4. https://www.thoracic.org/patients/patient-resources/resources/pulse-oximetry.pdf

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