Pulse Oximetry Pulse oximetry is a simple, non-invasive method used to measure the oxygen saturation level (SpO₂) in the blood and monitor heart rate. It works by placing a small sensor, usually on a finger, toe, or earlobe, which uses light absorption to estimate how much oxygen is carried by hemoglobin. Pulse oximetry is widely used in hospitals, clinics, and home settings to assess respiratory and cardiovascular status, especially in patients with lung diseases, heart conditions, or during an