Pulse oximetry is a test used to measure the oxygen level (oxygen saturation) of the blood. It's an easy, painless measure of how well oxygen is being sent to parts of your body furthest from your heart, such as the arms and legs.

A clip-like device called a probe is placed on a body part, such as a finger or ear lobe. The probe uses light to measure how much oxygen is in the blood. This information helps the doctor decide if a person needs extra oxygen.

Pulse oximetry may be used to see if there is enough oxygen in the blood. This information is needed in many kinds of situations. It may be used:

• As part of a routine wellness check.
• During or after surgery or procedures that use sedation.
• To see how well lung medicines are working.
• To check a person's ability to handle increased activity levels.
• To see if a ventilator is needed to help with breathing, or to see how well it's working.
• To check a person who has moments when breathing stops during sleep (sleep apnea).

Pulse oximetry is also used to check the health of a person with any condition that affects blood oxygen levels, such as:

• Heart attack
• Heart failure
• Chronic obstructive pulmonary disease
• Anemia
• Lung cancer
• Asthma
• Pneumonia

Your doctor may have other reasons to advise pulse oximetry.

All procedures have some risks. The risks of this procedure may include:

• Incorrect reading if the probe falls off or is not fully attached to the earlobe, toe, or finger
• Incorrect reading if there is dark nail polish or artificial nails.
• Incorrect reading due to skin coloring (pigmentation). Pulse oximetry may miss low oxygen saturations when used on darker skin. Talk with your doctor about the accuracy of your results if you have darker skin.
• Skin irritation from adhesive (if used) on the probe

Your risks may vary depending on your general health and other factors. Ask your doctor which risks apply most to you. Talk with them about any concerns you have.

Your doctor will explain the procedure to you. Make sure to ask any questions you have about the procedure. If a finger probe is to be used, you may be asked to remove fingernail polish.

Your doctor may have other instructions for getting ready.

You may have your procedure as an outpatient. This means you go home the same day. Or it may be done as part of a longer stay in the hospital. It depends on your condition and your doctor's methods. In most cases, pulse oximetry will follow this process:

1. A clip-like device called a probe will be placed on your finger or earlobe. Or a probe with sticky adhesive may be placed on your forehead or finger.
2. The probe may be left on for ongoing tracking.
3. The oxygen probe may be left on while you walk to see if your oxygen falls.
4. Or it may be used to take a single reading. The probe will be removed after the test.

You can go home after the test, unless you are in the hospital for another reason. You may go back to your normal diet and activities as instructed by your doctor. Your doctor may give you other instructions after the procedure.

Before you agree to the test or procedure make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person's qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how will you get the results
• Who to call after the test or procedure if you have questions or problems
• How much you will have to pay for the test or procedure