Blood oxygen level is the amount of oxygen circulating in the blood. Most of the oxygen is carried by red blood cells, which collect oxygen from the lungs and deliver it to all parts of the body.
The body closely monitors blood oxygen levels to keep them within a specific range, so that there is enough oxygen for the needs of every cell in the body.
A person’s blood oxygen level is an indicator of how well the body distributes oxygen from the lungs to the cells, and it can be important for people’s health.
Normal and low blood oxygen levels
A normal blood oxygen level varies between 75 and 100 millimeters of mercury (mm Hg).
A blood oxygen level below 60 mm Hg is considered low and may require oxygen supplementation, depending on a doctor’s decision and the individual case.
When blood oxygen level is too low compared to the average level of a healthy person, it can be a sign of a condition known as hypoxemia. This means that the body has difficulty delivering oxygen to all of its cells, tissues, and organs.
How is blood oxygen level measured?
The most efficient way to monitor blood oxygen levels is by an arterial blood gas or ABG test. For this test, a blood sample is taken from an artery, usually in the wrist. This procedure is very accurate, but it can be a little painful.
An ABG test can be difficult to do at home, so a person may wish to do an alternative test, using a small device known as a pulse oximeter.
A pulse oximeter is a small clip that is often put on a finger, although it can also be used on the ear or toe. It measures blood oxygen indirectly by light absorption through a person’s pulse.
Although the pulse oximeter test is easier, quicker, and not painful, it is not as accurate as the ABG test. This is because it can be influenced by factors such as dirty fingers, bright lights, nail polish, and poor circulation to the extremities.
For people who wish to purchase a pulse oximeter, there is a range of easy-to-use devices available online.
