Overview

A pulse oximeter is a device that checks to see how much oxygen your blood is carrying.

Usually a small clip is put on the end of your finger. (Sometimes it's put on your toe or earlobe.) The device shines a light beam through the skin. It estimates your oxygen level by measuring the percentage of your blood that's carrying oxygen. Your oxygen level (or oxygen saturation, SpO2) shows on the display screen.

Pulse oximeters are used in doctors' offices and hospitals. Your doctor may think it's a good idea to use one at home. This may be the case for people who have a condition that affects their oxygen levels. Examples include people who have long-term heart or lung problems or an infection like COVID-19. Choose a device that has been approved to give accurate readings. Talk to your doctor if you want help choosing one.

Why is it used?

Usually, low blood oxygen levels cause symptoms like fatigue or shortness of breath. But with some health problems, you may not have symptoms from low blood oxygen. Your doctor may suggest checking your oxygen at different times. This can help you know when you need medical attention even if you don't have symptoms.

How do you use a pulse oximeter?

Turn on the pulse oximeter. (Check that it has batteries.) Clip it on the end of a finger. Your nail should be facing up. You'll see the results in a few seconds.

The device gives two results: your blood oxygen level (SpO2) and your pulse rate (PR). Your doctor can help you know what numbers are normal for you.

The device may not show any results if you have cold hands or you wear nail polish or artificial nails. Warm your hand, or remove the nail polish or nail. Or try a different finger.

Your doctor may suggest checking your oxygen level at different times, during exercise, or anytime your symptoms get worse. Keep a record of your levels in case you need to show it to your doctor.

When should you call for help?

Your doctor probably told you what numbers to watch for when you use your pulse oximeter. If not, here is some guidance.

Call your doctor or nurse advice line if:

• Your blood oxygen level (SpO2) drops below 95%. This is true even if the number only drops when you're active.

If you have certain health problems, like COPD, your oxygen level may always be lower than 95%. Ask your doctor what oxygen number you should expect when using your pulse oximeter. Find out which number is a sign that you should call for help.

Watch closely for changes in your health, and be sure to contact your doctor or nurse advice line if:

• Your symptoms get worse.
• You are not getting better as expected.