Oximeter is quick and easiest way to monitor blood oxygen level and heart rate. Oximeter uses Infrared technology to measure blood oxygen level and heart rate. It can rapidly detect even the smallest changes in the oxygen levels. Pulse Oximeter The pulse oximeter is a small, clip-like device that attaches to a body part, like toes or an earlobe. It’s most commonly put on a finger, and it’s often used in a critical care setting like emergency rooms or hospitals. How to Use A clip-like device will be placed on your finger index finger One may feel a small amount of pressure, but there is no pain or pinching. The device is kept on for as long as needed to monitor your pulse and oxygen saturation. Once the test is over, the device will be removed.