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Pulse Oximetry

You may hear the terms “pulse ox” or “oximeter”, or questions on our lists and message boards regarding “what are your stats” or  “my o2 stats have been running”, etc. and wonder what these terms or phrases mean.

There are two common methods that your physician and/or respiratory therapist use to measure the amount of o2 (oxygen) concentration present in your blood. The first is a bit more invasive and is called an ABG or arterial blood gas.  This requires getting a specimen of blood by way of a needle-stick directly into an artery, not a vein, and usually obtained from the wrist area.  The second method is to use an oximeter (aka oxymeter)

What is a pulse oximeter? 

A pulse oximeter is an ingenious tool used to obtain oxygen (o2) saturation levels and pulse rates in a non-invasive fashion. If you have ever been to the doctor or hospital and have had a small device clipped onto your finger, much like a small, fat cloths pin, this was most likely an oximeter. They come in many shapes and sizes and serve a variety of uses, however, all with the same end result --  to monitor oxygen saturation rates. 

They are routinely used in operating rooms by anesthesiologists as part of their continuous vital-sign monitoring. They are used during the 6-minute walk tests done by our physicians or pulmonary rehab teams to determine possible supplemental oxygen needs, as well as used to evaluate our response to our current oxygen-use settings. They are used as a tool, as well, in overnight oximetry tests and in sleep labs to determine nocturnal (nighttime) drops in oxygen levels (hypoxemia) that may require supplemental oxygen-use and or other types of non-invasive breathing aids, such as Bi-PAPs or C-PAPs.

How does pulse oximetry work?

This is indeed a complex and interesting process. A pulse oximeter uses a beam of light transmitted through an area of the body, most generally a finger, however, toes and earlobes can be used as well under some circumstances, as in circulatory disorders or the presence of thick artificial nails or deep dark nail polish. The beam of light uses the color of our blood to determine the oxygenation of it. The color of our blood changes somewhat, depending on whether or not our red blood cells are adequately oxygenated.

Well-oxygenated blood is generally bright red in color, and will absorb most of the light being transmitted through the oximeter. Poorly oxygenated blood is more dark red-to-purple in color, and will not absorb the beam of light as well. Another fascinating aspect of the pulse oximeter is its ability to distinguish between venous blood levels and arterial blood levels. The mechanics of this magnificent technology allows it to distinguish between the pulsating venous blood and the constant flow of arterial blood. 

The measurements of oxygen levels obtained by way of pulse oximetry are extremely close to those obtained by the more invasive ABG. Regardless of the unit used -- the big, table-top units used in hospitals with running tapes or the smaller finger-tip, battery-operated units many COPDers have purchased -- the technology is the same.

Please understand that the explanation here is in lay terms from information taken from pages of technical information from an oximeter manual, and in no way is meant to indicate that they are simple mechanical devices, as nothing is farther from the truth. The ability to put such complex technology in such a small piece of equipment is nothing short of amazing. 

Do I need one? 

That is a question that only you can answer. Many of us on supplemental oxygen have decided to purchase our own personal pulse oximeter. We find comfort and security in being able to monitor ourselves and our oxygen needs. We use them when we get very short of breath to help guide us in determining what may be happening.

We use them while exerting ourselves or exercising to make sure we are maintaining adequate oxygen levels. If we notice severe drops or changes we are concerned about, we can then contact our physicians to decide how best to manage your individual concerns. 

Remember, oxygen is a medication!  We should never adjust our oxygen flow from the prescribed level with out first consulting our physician. Some physicians are happy that their patients have an oximeter and are being pro-active in their own care, while some other physicians are strongly against their patients having one. The concern, frequently, is that a patient will become obsessed with checking and become overly alarmed at even minimal drops. This is often not the case; however, it can and does happen. Only you can truly decide if the out-of-pocket expense and extra security is worth it to you.

Will insurance cover the cost?

This is also an excellent question, as the units are not inexpensive. We have found in our experiences that generally most insurance companies do not cover the cost of an oximeter. Some select insurance companies will cover the rental or purchase of one, although that is rare. Please check with your own insurance company before deciding and making a purchase

There are many sources for purchasing a pulse oximeter on the Internet. Search until you find the best price possible, as they change often. Some places require a physician’s prescription, where others do not. If you are considering such a purchase, make inquiries on our e-mail lists or message boards. Most people will be happy to share their experiences and information as to the best prices and or sources they have found.  COPD-International does not recommend or endorse one specific supplier over another.

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Last modified: June 17, 2002
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