What is Pulse Oximeter

A pulse oximeter is a device intended for the non-invasive measurement of arterial blood oxygen saturation and pulse rate. Oximeters are used medically by patients with asthma, chronic obstructive pulmonary disease (COPD), chronic obstructive airway diseases (COAD), and other respiratory conditions. Pilots use pulse oximeters to help guard against hypoxia. Pulse oximeter can also help athletes, such as mountain climbers and walkers, to improve their performance.

The finger tip pulse oximeter contains a dual light source and photo detectors. Typically it uses two LEDs (light-emitting diodes) generating red and infrared lights through a translucent part of the body. Bone, tissure, pigmentation, and venous vessels normally absorb a constant amount of light over time. Oxyhemoglobin and its deoxygenated form have significantly different absorption pattern. The arteriolar bed normally pulsates and absorbs variable amounts of light during systole and diastole, as blood volume increases and decreases. The ratio of light absorbed at systole and diastole is translated into an oxygen saturation measurement.

A more recent study has shown that the absorption changes can also be used to estimate blood volume of a patient.

Today there are many pulse oximeter manufacturers making different models of pulse oximeters. They mostly use the two-wavelength method; however each manufacturer has its own signal processing algorithms for deriving the oxygen saturation levels. With recent technological development, the accuracy has improved significantly especially during low perfusion and motion.