Pulse Oximeters and Oxygen Saturation

Pulse oximeters are great for patients who have gone through a pulmonary rehabilitation class and are knowledgeable about oxygen, oxygen saturation, and oximeters. But what if you haven’t been through a class. What do you need to know?

A pulse oximeter works by shining a light onto the blood vessels in your fingernail and measuring the color of your blood. Blood carrying a lot of oxygen is bright red, whereas blood with lower levels of oxygen becomes more bluish/purple in color. By measuring the color, you can get an idea of how well oxygenated your blood is.

Several things can affect the accuracy of the pulse oximeter reading that you get with a finger oximeter. If you wear nail polish (especially blue, green, black or metallic ones), then the reading might be inaccurate because the oximeter cannot ‘see’ your blood through the nail polish. If you have cold hands or poor circulation, then the reading might be inaccurate too, because you are not sending enough blood to your fingertip where the reading is being taken. If you smoke, you should not waste your time and money buying an oximeter! The oximeter can’t tell the difference between blood that is carrying oxygen, and blood that is carrying carbon monoxide. Smoking increases the carbon monoxide in your blood, and the pulse oximeter can give a falsely high reading. Another thing to remember about oximetry is that there is a delay of up to 30 seconds between what goes on in your lungs and the reading that you make at the fingertip. So be patient and wait in a relaxed state as you do your reading!

The amount of oxygen in your blood is described by the “oxygen saturation” – which is literally the percentage of your blood that is ‘fully loaded’ with oxygen.

We turned to PERF board member Dr. Brian Tiep for advice to those who wish to purchase their own oximeter. He is well known for his research with oxygen and breathing techniques in pulmonary patients.

My patients and I were lucky enough to work with Dr. Tiep for many years in research studies on oxygen and oximeters. There are now several on the market. Nonin is the company that invented the small finger oximeter and with which we did some of our research (see video below). Massimo and Innovo are other companies that make medical-grade pulse oximeters, but there are a lot more companies out there now that make these devices. These brands tend to be more expensive; however, we are more confident of their accuracy. Look for devices that advertise “plethysmograph and perfusion index,” as these tend to be more accurate. They are also more expensive (in the $100-$300 range) than the more everyday type of devices that can retail for as little as $15. The FDA discourages the use of the sports model for medicine and the medical model for sports. However, they are exactly the same, and you do not need a prescription for the sports models. These days, you can even get oximeters that send recordings directly to your mobile app. There is a large choice of oximeters on Amazon.com and many other stores. If you decide to purchase your own oximeter, obtain a doctor’s prescription and you may be able to deduct the cost of the oximeter from your income tax. Laws change, so check with your tax consultant. On rare occasions, an insurance company will reimburse the purchase cost if you get a prescription. It is worth checking on. However, as many oximeters are now available in stores or online and are relatively inexpensive, they can be a good low-cost investment.