Pulse Oximetry
Reviewed
Pulse oximetry is a quick, painless test that uses a small clip-like device (pulse oximeter) on a fingertip to measure the oxygen level in your blood. It is used to check for low blood oxygen (hypoxemia) in various settings, including routine checkups, monitoring of lung conditions, during surgery, and at home. The test carries no known risks, but factors like dark nail polish, artificial nails, darker skin pigmentation, poor circulation, cold skin, and tobacco use can affect accuracy. Results are typically given as a percentage (oxygen saturation). A normal level is 95%–100%, but lower levels may be acceptable for some individuals with chronic lung disease or at high altitudes. Contact your provider if your level is 92% or lower; seek immediate medical attention if it is 88% or lower. The test results may be 2% to 4% higher or lower than your actual blood oxygen level. For more precise measurement, your provider may order an arterial blood gas test.
Preparation and collection
Remove dark nail polish from the finger being tested. Avoid artificial nails on that finger. Inform your provider about factors that could affect accuracy (e.g., poor circulation, cold skin, tobacco use).
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- Dark nail polish, artificial nails, darker skin pigmentation, poor circulation, cold skin, and tobacco use may cause inaccurate results.
- Pulse oximetry results may be 2% to 4% higher or lower than the actual blood oxygen level.
- The test reflects oxygen saturation but does not measure other blood gas parameters; a more accurate measurement may require an arterial blood gas test.
What to do next
Discuss results with your healthcare provider. For at-home monitoring, follow your provider's guidance on when to contact them or seek emergency care.