Pulse Oximeter (IMAGE) College of Medicine at Urbana-Champaign Caption The ability to accurately measure oxygen saturation without the use of a pulse oximeter is something that has never been achieved, until now. The pulse oximeter, a non-invasive medical device usually placed on the patient's finger, measures the proportion of oxygen in the blood, combining status of the two major circulatory systems, the heart and the lung. Credit © University of Illinois College of Medicine at Urbana-Champaign Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.