What is blood oxygen saturation?

Blood oxygen saturation (SpO2) is the percentage of oxygen-saturated hemoglobin in the blood relative to the total hemoglobin in the blood. It is an important clinical indicator of the oxygenation status of the blood and can be used to assess the effectiveness of respiratory function.

SpO2 is measured using a device called a pulse oximeter, which is a non-invasive medical device that clips onto a finger, earlobe, or toe and uses light waves to measure the amount of oxygen in the blood. The pulse oximeter transmits two wavelengths of light through the skin and measures the amount of light that is absorbed by the hemoglobin in the blood. The amount of absorbed light is then used to calculate the SpO2.

Normal SpO2 levels are between 95% and 100%. Levels below 90% are considered low and may indicate that the person is not getting enough oxygen to their tissues. Low SpO2 levels can be caused by a variety of conditions, including:

- Pneumonia

- Asthma

- Chronic obstructive pulmonary disease (COPD)

- Heart failure

- Anemia

- Carbon monoxide poisoning

SpO2 monitoring is an important part of medical care and can be used to:

- Screen for and diagnose respiratory problems

- Monitor the effectiveness of respiratory treatments

- Guide the management of patients with chronic respiratory conditions