Oxygenated blood is carried to the organs and tissues of the body by the hemoglobin in the red blood cells. Oxygen saturation levels refer to the amount or percentage of red blood cells that are full with oxygen. Oxygen saturation may also be referred to as blood oxygen level.
Normal oxygen saturation levels vary slightly depending on age and activity. A blood oxygen level of less than 90 percent is considered abnormal. The organs in the body need a continuous supply of oxygen to function properly. If the blood oxygen levels in the body become too low, various problems can develop.
When oxygen levels are too low, the condition is known as hypoxemia. Various symptoms can occur depending on how low the oxygen saturation is. Symptoms may include shortness of breathing, fatigue, headache, and confusion. Because oxygen must be supplied to the heart and brain constantly, death can occur if blood oxygen levels become too low.
Oxygen saturation levels may be measured as part of a physical exam or if a patient is showing signs of breathing problems. There are two main ways to do this, including taking blood from an artery, which is called an arterial blood gas test, and obtaining a reading with a pulse oximeter. An arterial blood gas test is considered more accurate, however, it is invasive.
To measure oxygen saturation with an oximeter, a probe is placed a person’s finger, toe, or earlobe and the pulse oximeter machine displays a reading. A reading can be affected by a person moving, fingernail polish, and cold fingers. A pulse oximeter is a quick way to determine oxygen saturation levels.
Various conditions can cause a low oxygen saturation level in the blood. People who have breathing problems, such as asthma or pneumonia, may not be able to get enough oxygen into their lungs. This causes the oxygen levels in the blood to drop. Other conditions that can impair breathing include a drug overdose, head injury, and cardiac conditions, such as a heart attack.
If oxygen saturation is too low, treatment will be needed. The primary treatment for low oxygen saturation is oxygen therapy. Oxygen can be given through a mask or nasal prongs. The amount of oxygen given will depend on how low the oxygen saturation is in the blood. Some people have chronically low oxygen saturation levels and may need to be on oxygen permanently. Various types of home oxygen devices are available.