SpO2 is the functional oxygen saturation measured by pulse oximetry. A normal SpO2 reading is usually considered to be above 94%. An SpO2 of 90-94% can signal that a patient may have a new or chronic respiratory problem, or that they may be progressing to hypoxemia. Many clinical definitions of hypoxemia (i.e. low oxygen concentration in the blood) use a cutoff of 90%, though depending on the context, SpO2 values above 90% may be abnormal (e.g. a healthy, young adult at sea level should be 96-100%. Similarly, depending on the context, an SpO2 less than 90% may be physiologically appropriate (e.g. at high altitude). Read more about the “Optimal SpO2 target for Patients with Respiratory Failure”
References: Lifebox Pulse Oximetry Learning Module
Keywords: normal SpO2, hemoglobin