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Understanding Normal Blood Oxygen Level

When you breathe, oxygen from the ambient air travels through your nose, down your windpipe and into your lungs where it enters the bloodstream. It then travels through the blood bound to hemoglobin – a protein found in red blood cells – to oxygenate the cells, tissues and organs of your body.

Oxygen saturation (SpO2) is a term referring to the concentration of oxygen in the blood, or the percentage of hemoglobin molecules that are saturated with oxygen. One hemoglobin molecule can carry 4 oxygen molecules.

How is Oxygen Saturation Measured?

pulse oximeter oxygen saturation levelYour oxygen saturation level can be estimated with a pulse oximeter, a small medical device that clips onto your finger. You can click here to view and purchase the pulse oximeter sold directly on the Inogen online store. The most accurate way to measure oxygen saturation, however, is through a blood test known as an arterial blood gas study.

Normal blood oxygen level ranges between 95-100%. It’s not uncommon for people with lung disease to have below normal levels. In general, supplemental oxygen is prescribed when the oxygen saturation level stays at or below 88 percent. It’s normal for oxygen saturation levels to fluctuate with activity. If your oxygen saturation level runs low on an ongoing basis, whether at rest, during activity or while you sleep, talk to your health care provider about using supplemental oxygen.

Signs and Symptoms of Low Oxygen Levels

In order to function properly, your body needs a certain amount of oxygen circulating in your bloodstream at all times. When the level of oxygen in the blood drops, hypoxemia, or low blood oxygen levels occur. Hypoxemia can lead to hypoxia, or low oxygen in the tissues. Ongoing hypoxemia in COPD can lead to pulmonary hypertension (high blood pressure in the lungs) and secondary polycythemia (an overproduction of red blood cells); it can also lead to other complications.

Although signs and symptoms of hypoxemia or hypoxia may vary from person to person, the following are the most common:[1]

  • Confusion
  • Changes in skin color from blue to cherry red
  • Fast heart beat
  • Fast breathing
  • Shortness of breath
  • Sweating
  • Wheezing and/or cough

How Oxygen Therapy Can Help

Treatment with supplemental oxygen increases the amount of oxygen in your bloodstream, which increases the amount of oxygen to your cells, tissues and organs. If you have a lung disease that impairs your breathing, getting more oxygen can help you breathe better and live longer. Whether you choose a home oxygen concentrator like the Inogen at Home or a portable oxygen concentrator like the Inogen One G3 or Inogen One G4, supplemental oxygen helps reduce the risk of hypoxemia or hypoxia by providing you with oxygen as needed or on a continuous basis, 24/7, Inogen has a solution for all your oxygen needs.


[1] WebMD. “Hypoxia and Hypoxemia”. Last reviewed June 12, 2014.

By Deborah Leader RN, BSN, PHN



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