The normal reference range for arterial oxygen saturation (Sao₂) is 95% to 100%.

Pulse oximetry measures the oxygen saturation noninvasively, without the need to get the arterial blood gas study. Pulse oximetry is indicated during the emergency management of airway, and to monitor the adequacy of oxygen delivery. Oxygen is generally indicated in patients with acute myocardial infarction, upper airway obstruction, aspiration, sepsis, and in other critically ill patients, including possibly patients with delirium.