Hypoxemia is a low level of oxygen in the blood. It starts in blood vessels called arteries. Hypoxemia isn't an illness or a condition. It's a sign of a problem tied to breathing or blood flow. It may lead to symptoms such as:

• Shortness of breath.
• Rapid breathing.
• Fast or pounding heartbeat.
• Confusion.

A healthy level of oxygen in the arteries is about 75 to 100 millimeters of mercury (mm Hg). Hypoxemia is any value under 60 mm Hg. Levels of oxygen and the waste gas carbon dioxide are measured with a blood sample taken from an artery. This is called an arterial blood gas test.

Most often, the amount of oxygen carried by red blood cells, called oxygen saturation, is measured first. It is measured with a medical device that clips to the finger, called a pulse oximeter. Healthy pulse oximeter values often range from 95% to 100%. Values under 90% are considered low.

Often, hypoxemia treatment involves receiving extra oxygen. This treatment is called supplemental oxygen or oxygen therapy. Other treatments focus on the cause of hypoxemia.