Learning About Pulse Oximetry for Children

Pulse oximetry is a quick, painless test that measures the oxygen level (oxygen saturation) in your child’s blood. It shows how much oxygen is being carried in the blood.

The test uses a small device (probe) that gently clips on the tip of a finger, an earlobe, or a toe. Most teens can use an adult-size clip. You can get a special pediatric-size clip for young kids. For babies, it’s a strap that fits around the wrist or foot.

It works by shining a light through the fingernail, tissues, and blood cells. A sensor on the other side detects how much light gets through the finger to calculate the oxygen level.

Pulse oximetry is done to check the oxygen levels in your child's blood. Low oxygen levels can be caused by lung problems, heart problems, or other conditions. The test results are shown as your child’s oxygen saturation level, which is also called O2 sat or SpO2. The percentage of oxygen in your child’s blood is compared with the greatest amount the blood is able to carry.

Follow the instructions that come with your oximeter. Here are the usual steps:

1. Turn it on.
2. Make sure your child is relaxed and still. For babies, wait until your baby is calm and settled. For older children and teens, have your child sit quietly for a few minutes. Make sure your child's hands or feet are warm.
3. Place the sensor on your child.
   • For babies: Place the sensor or wrap-style probe on your baby's foot, toe, or hand, depending on the size of your child and the type of probe. Make sure the sensor is snug but not too tight.
   • For children and teens: Clip the device on the end of a finger. Use a finger that doesn't have nail polish or an artificial nail. Keep the fingernail facing up. Have your child hold the finger still.
4. You'll start to see results in a few seconds. Wait until you see one steady number for the oxygen level. Your child’s doctor can help you know what numbers are normal for your child.

Many things can affect the results from a pulse oximeter. These include darker skin colors and poor blood flow in the finger. The device also may not show accurate results if your child has cold hands or wears nail polish or artificial nails.

If your child has a darker skin color, a pulse oximeter may miss low oxygen levels. You may not know that your child’s levels are low and that your child needs medical care.

It's important to watch for symptoms along with changes in the oxygen levels. Talk with your child's doctor about symptoms your child may have with low oxygen levels. For infants, symptoms may include fast breathing, fussiness, or difficulty feeding. For children and teens, symptoms may include fatigue, weakness, and shortness of breath.