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Hypoxia and hypoxemia are two terms that refer to decreased oxygen availability, which can lead to health problems. Although they sound similar, and one can cause the other, they are different. Hypoxemia refers specifically to low levels of dissolved oxygen in the blood. This can lead to the development of hypoxia, or decreased oxygen supplies to various organs and tissues. Hypoxia and hypoxemia can both be very serious, as the body's tissues are not designed to function without oxygen.
In the case of hypoxemia, a doctor can perform a test to measure the amount of dissolved oxygen present. If the patient's oxygen saturation level is below 90%, this is indicative of hypoxemia. For some reason, not enough oxygen is getting into the patient's blood. Some causes can include a slowed respiratory rate, fluid in the lungs, or lung disease. Over time, the decreased oxygen availability can start to create complications.
With hypoxia, tissues and organs experience oxygen deprivation and start to develop problems. These can include cell death that leads to tissue necrosis, where tissues die because they do not get enough oxygen. In the brain, a condition known as cerebral hypoxia can develop where brain cells experience a decline in function because of the oxygen deprivation. Hypoxia and hypoxemia can occur at the same time, as the low blood oxygen causes tissues to develop hypoxia. Patients can also have hypoxia because of anemia, which causes a generally low supply of oxygen-carrying red blood cells, or because of an obstruction in the supply of blood.
Treatments for hypoxia and hypoxemia are similar, as the goal in both cases is to get more oxygen into the patient. The patient may need to wear an oxygen mask or could require intubation if he or she cannot breathe independently. The doctor will prescribe a high oxygen mixture, rather than straight air, to increase the amount of oxygen getting into the lungs. This can facilitate gas exchange and raise blood oxygen levels.
If the patient's tissues continue to develop hypoxia, the doctor may need to run some tests to learn more about the patient's lung function and check for issues like obstructions that might be occluding blood flow and making it hard for an area of the body to get the blood it needs. With hypoxia and hypoxemia, it is also possible to see tissues dying because of lack of nutrients. This indicates that the overall flow of blood is not as robust as it should be and cells cannot get the compounds they rely upon to function. The doctor may take steps to raise blood pressure or increase blood flow.
I read somewhere that the ultimate cause of every human death is a form of hypoxia. Eventually the cells in the brain become oxygen-deprived and all brain activity stops.