An oximetry test, also known as pulse oximetry, is a simple and painless medical test that measures the amount of oxygen in your blood. A small, clip-like device called a pulse oximeter is placed on a fingertip, earlobe, or toe to measure the oxygen saturation level by using red and infrared light. This test is used to check overall oxygen levels, diagnose and monitor lung and heart conditions, and assess how well lung medications are working.  

Basically, pulse oximetry is a painless, noninvasive method of measuring the saturation of oxygen in a person’s blood.