Pulse Oximetry
Reviewed
Also called: Pulse Ox, Oxygen saturation monitor, Finger pulse oximeter
Pulse oximetry is a test that uses a small, clip-like device called a pulse oximeter (Pulse Ox) to measure oxygen levels in your blood.
Specimen: None
Urgent safety information
If it falls to 88% or lower, seek immediate medical attention. If you are using an at-home oximeter, watch for signs or symptoms that you have low oxygen levels, such as: Lips, nails, or face that look bluish (cyanosis), Trouble breathing or shortness of breath, Chest pain or tightness, Fast heart rate
Why this test may be ordered
- To check blood oxygen level as part of a routine checkup.
- To monitor lung function in conditions like COPD, lung cancer, heart failure, asthma, or COVID-19.
- To assess the effectiveness of medicines for lung disease.
- To monitor oxygen levels before, during, and after surgery.
- To evaluate for sleep apnea (repeated breathing pauses during sleep).
Preparation and collection
Dark nail polish on the finger being tested can block the light emitted from the oximeter. Other things that may cause inaccurate results can include: Artificial nails, A darker skin pigmentation (color), Poor circulation, Cold skin, Tobacco use
A small electronic device called a pulse oximeter will be clipped to a part of your body, usually your fingertip. After a few seconds, the oximeter will provide a readout of your heart rate (pulse) and oxygen level.
There is no known risk to having pulse oximetry.
Understanding results
If a result or symptoms suggest an emergency, get emergency medical help right away.
Results are often given as oxygen saturation levels.
- 95% to 100%: A normal oxygen saturation level ranges between 95% and 100%. Limitation: Pulse oximetry results may be 2% to 4% higher or lower than your actual blood oxygen level. Next step: If you have questions about your results, talk to your provider.
- 92% or lower (but above 88%): Saturation levels may be somewhat lower and considered acceptable if you have a lung disease such as COPD or pneumonia. Limitation: Your levels may also be lower if you live in an area with a higher elevation, where there is less oxygen in the air. Next step: Contact your provider if your oxygen saturation level is 92% or lower.
- 88% or lower: The longer your blood oxygen level stays low, the higher the risk is of damage to your tissues and organs. Limitation: For a more accurate result, your provider may do a blood test called an arterial blood gas. Next step: If it falls to 88% or lower, seek immediate medical attention.
- 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
If you have questions about your results, talk to your provider.
- What is my oxygen saturation level?
- Do I need to monitor my oxygen levels at home?
- What should I do if my oxygen level falls below 92%?
- How does my lung condition affect my target oxygen level?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.