A pulse oximeter is a handy medical device that uses two frequencies of light â red and infrared â to determine the percentage of hemoglobin in the blood that is saturated with oxygen, or your oxygen saturation level. When oxygen saturation is measured using a pulse oximeter, it is referred to as Sp02. When it is measured by way of a blood test known as an arterial blood gas study, it is referred to as Sa02.
What is the Normal Oxygen Saturation Level?
Your oxygen saturation level is dependent upon a number of factors including your health condition, breathing rate and activity level. Normal oxygen levels range between 95-100 percent. Values under 90% are considered low.
Supplemental oxygen is generally covered by Medicare and other insurance companies when your oxygen saturation level, as measured by pulse oximetry, is at or below 88 percent at rest and/or your partial pressure of oxygen (Pa02), as measured by an arterial blood gas study, is at or below 55 mm Hg.
Pulse Oximetry and Oxygen Therapy
A pulse oximeter can be a useful and reassuring tool if youâre using home oxygen therapy. Not only will using a pulse oximeter at home help you better manage your health condition, but it will allow you to adjust your oxygen flow rate â under the strict guidance of your doctor â according to your activity level.
Tips for Using Pulse Oximetry at Home
You can purchase a home oximeter either online or from a medical supply company or pharmacy. Most models made for in-home use are inexpensive and easy to use. Simply attach the pulse oximeter probe to your finger and wait until the LED screen indicates your Sp02. It should only take a couple of seconds. The pulse oximeter will also measure and display your heart rate. You may want to record your daily Sp02 readings in a health journal or on a piece of paper to later show your health care provider. This way, she can determine if your oxygen flow rate is meeting your needs during all of your activities.
Why itâs Important to Know Your Oxygen Saturation Level
Itâs important to know your oxygen saturation level if you have a health condition that affects how much oxygen is in your blood. When your blood oxygen level is low, the cells and tissues of your body have less oxygen. This can negatively impact all your bodily functions. Â It can also put a strain on your heart and your brain.
According to the American Thoracic Society, most people need an oxygen saturation level of at least 89% to keep their cells healthy. Having a blood oxygen level lower than this for short periods of time is not believed to be dangerous. However, your cells and tissues may become damaged if your oxygen saturation level runs low many times or continuously.2
How to Obtain an Accurate Pulse Oximetry Reading
To get the most accurate reading from your pulse oximeter, there needs to be enough blood flow to the hand and finger wearing the device. This means the best reading occurs when your hand is warm, relaxed and below the level of your heart.2
Factors that May Influence an Sp02 Reading
Most oximeters are reasonably accurate, giving you a reading of 2% over or 2% under what your saturation would be if measured by an arterial blood gas study.2 A reading may be less accurate, however, if any of the following apply:
Tips for Getting a Better Reading
An inaccurate pulse oximetry reading can be misleading and alarming. To get the best reading possible, consider the following tips:
 Mayo Clinic. âHypoxemiaâ. January 4, 2013.
 American Thoracic Society. âPulse Oximetryâ. Am J Respir Crit Care Med Vol. 184, P1, 2011 â˘ Online Version Updated December 2013 www.thoracic.org. ATS Patient Education Series ÂŠ 2011 American Thoracic Society.
By Deborah LeaderÂ RN, BSN, PHN