Definition

By Mayo Clinic Staff

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 an issue tied to breathing or blood flow.

Hypoxemia may lead to:

  • Shortness of breath.
  • Fast breathing.
  • Fast or pounding heartbeat.
  • Not thinking clearly.

A healthy level of oxygen in the arteries is about 75 to 100 millimeters of mercury (mm Hg). Healthcare professionals use a sample of blood taken from an artery to measure levels of oxygen and the waste gas carbon dioxide. This is called an arterial blood gas test.

Most often, the first measure is the amount of oxygen that red blood cells carry. This is called oxygen saturation. A medical device that clips to the finger, called a pulse oximeter, measures oxygen saturation. Healthy pulse oximeter values range from 95% to 100%. Values under 90% are low.

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

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Feb. 20, 2026