Pulse Oximetry

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. When you breathe, your lungs take in oxygen and send it into your bloodstream. This oxygen-rich blood is carried by your red blood cells into your heart, which pumps it to the rest of your body.

But if a health condition causes your blood oxygen level (oxygen saturation) to get too low (a condition called hypoxemia), it can make it hard for your body to work properly. The longer your blood oxygen level stays low, the higher the risk is of damage to your tissues and organs. Pulse oximetry is a painless and quick way to find out if your oxygen level is too low.

Quick treatment of low blood oxygen may help you avoid serious complications.

Why this test is done

Your provider may give you a pulse-oximetry test as part of a routine checkup. You may also get the test if you:

• Have a condition that affects your lung function. These can include chronic obstructive pulmonary disease (COPD), lung cancer, heart failure, asthma, and COVID-19.
• Are taking medicine to treat lung disease. The test can show how well the medicine is working.
• Are having surgery. Your blood oxygen level may be checked before, during, and after your procedure.
• Have sleep apnea. This is a disorder that causes you to repeatedly stop breathing during sleep.
• Use extra oxygen (oxygen therapy). This may help your provider determine if you are getting the right oxygen flow rate from your oxygen device.
• Have shortness of breath (feeling like you can't get enough air).

How to prepare

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

Other names for this test

pulse ox, oxygen saturation monitor, finger pulse oximeter