Oxygen Saturation in Arterial Blood

What Does This Test Measure?

Oxygen saturation (SaO₂) is the percentage of hemoglobin molecules carrying oxygen in your arterial blood. A normal value typically indicates efficient oxygen transfer from the lungs to tissues. This test is often used alongside pulse oximetry (a non-invasive device measuring oxygen levels in fingers/toes) to evaluate respiratory health, especially in conditions like asthma, COPD, or sleep apnea.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms like shortness of breath, fatigue, or if they suspect lung disease, heart problems, or other conditions affecting oxygen levels. It’s also used during surgeries, in intensive care settings, or before procedures that could impact breathing.

How Is the Test Done?

A small blood sample is taken from an artery (often in your wrist or arm) using a needle. The blood is sent to a lab where it’s analyzed for oxygen saturation. The process takes about 5–10 minutes and is usually painless but may cause a brief sting.

What Are Common Results?

Results are reported as a percentage (e.g., 95% SaO₂). While reference ranges vary by lab, values below 90% may signal low oxygen levels requiring further investigation. Mild deviations might be normal for some individuals, so discuss results with your provider.