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.