A pulse oximeter is a small device that measures your blood oxygen level. It does this by using beams of light, without the need for a blood sample. When placed on your finger, the pulse oximeter analyzes the light that passes through your finger to determine the percentage of oxygen in your red blood cells.

These devices can give an estimate of blood oxygen levels. Certain factors such as poor circulation, skin pigmentation, skin thickness or temperature, current tobacco use, and fingernail polish can all affect accuracy. For the best reading, make sure your finger is warm, relaxed, and held at a level below your heart. Remove any finger polish. Sit quietly during the reading. Your oxygen saturation level and heart rate will appear on a small screen on the top of the device. Pulse oximeters can be used monitor blood oxygen levels in case of illness such as COVID-19 or lung disease, such as asthma or COPD. Talk with your health care provider about how to use the pulse oximeter and what to do when levels drop too low.