How Should I use an Oximeter?

Dear Dr. Mahler:

One of my children recently bought an oximeter for me to check my oxygen level? However, I am not exactly sure how to use this information. My doctor has told me that I have severe COPD with emphysema, but I do not use oxygen. I take Tudorza and Symbicort both twice a day and ProAir as needed. I usually get a chest cold in the winter and then take prednisone and a Z-pak.  I keep fairly active at the senior center and participate in their exercise programs usually twice a week. 

Barbara from Clearwater, FL

Dear Barbara,

An oximeter is a medical device that measures oxygen saturation. This is often abbreviated SpO2 where S = saturation; p = pulse; and O2 = oxygen.

The device passes two waves of light through the finger to measure the percentage of hemoglobin, the protein in the red blood cell, that carries oxygen. Most devices also measure heart rate.

Oximeter which measures the percentage of oxygen being carried by hemoglobin in the blood

Oximeter which measures the percentage of oxygen being carried by hemoglobin in the blood

 

The top piece of the oximeter emits light waves that pass through through the finger. The bottom piece has a sensor. Absorption of light differs between blood loaded with oxygen and blood lacking oxygen.

The top piece of the oximeter emits light waves that pass through through the finger. The bottom piece has a sensor. Absorption of light differs between blood loaded with oxygen and blood lacking oxygen.

What do the numbers mean? A normal value is 95% or higher. A value of 90% or higher is considered adequate or acceptable. A value of 88% or below is considered low and qualifies for oxygen use.

Are there any limitations? Yes, there are a few to know about. First, you must have good blood flow to the finger for the oximeter to be accurate. Poor blood flow can occur if your hand is cold or if you are moving a lot, like shivering. If you measure the oxygen level when walking, make sure to keep your finger/hand steady to get an accurate recording. Also, an irregular heart rhythm can affect the accuracy. Those who have atrial fibrillation (a fib) have an irregular heart beat and the values can change based on how much blood reaches the finger.

I find that some patients in my practice are overly dependent on knowing their SpO2. It is useful as a guide as how the lungs are working, but does not indicate how you are feeling or how good or bad is your breathing. Certainly, it is reasonable to check the level particularly if you are having a “bad breathing day.”

Finally, you are fortunate that one (or more) of your children is interested in your COPD and wants to help out. Make sure that you share this response with your family to help them understand what the SpO2 means.

Best wishes,

Donald A. Mahler, M.D.