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Tuesday, October 4, 2011

What is a normal oxygen percentage in the blood?

Pocket size pulse oximeter
Your question:  What is the normal percentage of oxygen in the blood?

My humble answer:  I believe you are referring to pulse oximetry, or spo2.  Your blood has many red blood cells (RBC), and each RBC has a hemoglobin molecule.  After passing through the lungs, an oxygen molecule binds with a hemoglobin molecule.  So, an spo2 gives a percentage of hemoglobin molecules (in arterial blood) that are carrying an oxygen molecule.  A normal percentage is 98%.  However, anything over 90% is acceptable.  As we age, sleep, and with various disease conditions it's normal for this percentage to decrease.  Pulse oximetry is now considered the 5th vital sign after blood pressure, heart rate, respiratory rate and temperature.


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