Oxygen saturation (medicine)
Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal blood oxygen levels in humans are considered 95–100 percent. If the level is below 90 percent, it is considered low resulting in hypoxemia. Blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, and should be promptly addressed. Continued low oxygen levels may lead to respiratory or cardiac arrest. Oxygen therapy may be used to assist in raising blood oxygen levels. Oxygenation occurs when oxygen molecules () enter the tissues of the body. For example, blood is oxygenated in the lungs, where oxygen molecules travel from the air and into the blood. Oxygenation is commonly used to refer to medical oxygen saturation.
Dennis Lewis
In his writing and teaching about breathing, Lewis maintains that many people habitually hyperventilate — by which he means taking rapid shallow breaths from the top of the chest instead of breathing more naturally with the entire abdomen and back — and this reduces carbon dioxide levels in the blood too rapidly and thus causes an oxygen shortage in the brain and body. The result of lower oxygen he claims is, among other things, anxiety, tension, or irritability. There is disagreement about the benefits of increased oxygen blood levels. According to Dr. Mary Purucker, a pulmonary specialist in the U.S. Food and Drug Administration Center for Drug Evaluation and Research, there are no long-term, well-controlled scientific studies that support claims of benefit for increased oxygen in healthy people. There are many like Lewis today, however, including breath therapists, breathing teachers, MDs, and researchers, who maintain that good breathing increases the likelihood of a longer, healthier, more-rewarding life—physically, emotionally, and spiritually.