A pulse oximeter measures your blood oxygen levels and pulse. A low level of oxygen saturation may occur if you have certain health conditions. Your skin tone may also affect your reading.

Pulse oximetry is a noninvasive test that measures the oxygen saturation level of your blood.

It can rapidly detect even small changes in oxygen levels. These levels show how efficiently blood is carrying oxygen to the extremities furthest from your heart, including your arms and legs.

The pulse oximeter is a small, clip-like device. It attaches to a body part, most commonly to a finger.

Medical professionals often use them in critical care settings like emergency rooms or hospitals. Some doctors, such as pulmonologists, may use them in office settings. You can even use one at home.