Everyone Should Know About Blood Oxygen Levels . What are Blood Oxygen Levels? The amount of oxygen in the blood circulating in the body is called the blood oxygen level. The oxygen in the blood is carried by a specific type of cell called the Red Blood Cells (RBCs) that transport the oxygen from the lungs to different body parts. As we know, oxygen is an essential element for the proper functioning of our organs. Thus, the quantitative value of the person’s oxygen levels determines the lung function and the distribution in the body. What is oxygen saturation (SpO 2 )? ‘S’ in Sp0 2 refers to saturation, ‘p’ in Sp0 2 refers to pulse or pulsatile flow, ‘0 2 ’ in Sp0 2 refers to Oxygen, Oxygen saturation measures the percentage of oxyhemoglobin (oxygen-bound hemoglobin) in the blood, and it is represented as arterial oxygen saturation (SaO2) and venous oxygen sat...