O2 Levels in Humans
The cells of the body require oxygen, or O2, to stay alive and to function properly. Oxygen levels can vary greatly from one day to the next and even within a single day, particularly in people who have respiratory problems. Abnormalities in blood O2 levels may be a sign of disease or health problems. Measurements of oxygen levels are one way that health professionals evaluate a patient's health.
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What is Normal?
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According to the Mayo Clinic, oxygen levels can be measured by using either a blood test or a small monitor placed on the finger, which is known as a pulse oximeter. Arterial blood gases, or ABG, are tested from a blood sample. Along with O2 level, this test measures the acidity of the blood and the level of carbon dioxide in the blood. The pulse oximeter measures the saturation of O2 in the blood and is used as an estimate of blood O2 levels. Readings between 95 and 100 percent are considered normal in most cases.
Low Oxygen Levels
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A pulse oximeter reading under 90 percent is diagnostic of hypoxemia, or low blood oxygen. It can be caused by respiratory diseases such as lung cancer, chronic obstructive pulmonary disease, interstitial lung disease, cystic fibrosis or pneumonia. Other conditions such as shock or congenital heart disease may also trigger low oxygen levels. Low levels of O2 can cause shortness of breath, fatigue, irritability, headaches and difficulty concentrating. Oxygen levels that continue to drop may be a medical emergency and require hospitalization.
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High Oxygen Levels
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Too much oxygen can also cause problems. The brain of a person with high oxygen levels may not send signals to the body to breathe. This is a concern for a person with sleep apnea, a condition in which a person stops breathing periodically while sleeping. In order to prevent problems with high O2 levels, oxygen levels may be adjusted based on ABG levels or pulse oximeter readings.
Oxygen Therapy
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Oxygen therapy may be needed for people who are unable to get adequate oxygen into their system. Oxygen may be required in the short term for people who have injuries to their lungs, or it may be required in the long term in people who have chronic lung disease or sleep apnea. The goal of oxygen therapy is to keep blood oxygen levels within the normal range, which helps prevent damage to the heart, lungs and brain cells. Some people need oxygen therapy only during sleep or while exercising. After O2 therapy, a person may feel more energetic and rested.
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References
Resources
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