How to Read a Pulse Oximeter

A pulse oximeter works by passing an infrared beam through the capillary bed to a sensor on the other side. Before oxygenation by the lungs, blood is a darker shade of red. The small instrument measures the intensity of both shades of blood, detects the heart rate, and then subtracts the amount of the darker unoxygenated blood through a series of calculations. The result is the percentage of oxygen-saturated blood. These, along with the heart rate, appear on the display monitor.

Instructions

Difficulty: Easy

1. Determine the source of power for the pulse oximeter. Some plug into the wall while others have a rechargeable battery.
2. Select the appropriate probe. The earlobe and finger are the usual choices, and each requires a different probe. If the finger is used, remove all nail polish so you have good contact with the skin. Clean the skin to remove oil.
3. Turn the instrument on and wait for it to calibrate and run through a series of checks. This may take a few seconds.
4. Place the probe at the site you have prepared. Avoid using force when attaching the probe. Although it is cushioned, excessive pressure can cause injury to delicate skin.
5. Wait a few seconds for the pulse and percentage of oxygen saturation to appear on the monitor screen.
6. Assess the numbers. A normal oxygen level on room air is in the high 90s. Some things that can affect the oxygen level are a change in position, increase in activity or change in condition. Investigate anything below 95 percent.
7. Check the heart rate displayed on the monitor. The normal adult heart rate is 60 to 80 beats a minute. The adolescent's normal rate is 60 to 105, and a child 5 to 12 years of age has a rate of 60 to 120. Infants and younger children have a much higher heart rate. Children between 1 and 5 years of age have a heart rate between 80 and 150 beats per minute, and infants' hearts beat between 120 to 150 a minute.

Tips & Warnings

• Do not rely solely on an instrument. Use your own observations of the person you are monitoring for changes in their condition.
• Proper contact with the skin is important for an accurate reading.
• An oxygen level below 90 percent indicates a low oxygen level (hypoxemia) and requires attention immediately.