COPD Lexicon: Pulse Oximetry Terms To Know

Pulse oximeters are neat little tools. They can help you monitor your oxygen levels. They used to only be available in hospitals. Now you can buy them at stores. So, what are they? How can they help you?

Basic pulse oximetry terms to know


This is a molecule that looks and acts like an inner tube. As oxygen molecules enter your bloodstream, they sit on the inner tube and go for a nice ride. So, in this way, hemoglobin carries oxygen molecules to all the cells of your body.

Arterial blood

Blood acts as a river. As it travels through your lungs it picks up oxygen molecules. They jump aboard hemoglobin molecules. When this happens, blood turns a bright red color. So, under ideal circumstances, arterial blood is freshly oxygenated red blood. It carries oxygen-carrying hemoglobin to all the cells of your body. Once they arrive at the desired cell, oxygen jumps off hemoglobin and enters the cell.

Hemoglobin Oxygen Saturation(SpO2)

It’s represented as a percentage. It’s an estimate of how well your hemoglobin is saturated (s) with oxygen (O2). It’s the percentage of oxygen you inhale that gets to your bloodstream. It’s an estimate of how well your lungs are oxygenating your arterial blood.1-2

Normal SpO2

A couple of hemoglobin molecules will always remain empty. So, a normal SpO2 is 98%.2

Acceptable SpO2

Acceptable is 90% or greater. Or, acceptable is whatever your doctor deems acceptable. Many doctors find that 88-92% is acceptable for COPD.3-4

Oxygen saturation

This is another way of saying SpO2.


This is another abbreviated way of saying SpO2


This is yet another abbreviated way of saying SpO2.


This is how some people describe SpO2. It is not accurate. It is not a stat. It’s a sat. Sorry, I just thought I’d throw this in here.

Pulse Oximeter

It’s a small, portable device that measures your SpO2. It slips over your finger. Essentially, all it does is send light through your finger. The light is received by a sensor on the other side of your finger. This estimates your SpO2 using your pulse. Because it uses your pulse, it also gives you your pulse or heart rate. It also measures your heart rate. Both are displayed on the LED.1-2

To note: The “p” in SpO2 refers to “pulse oximeter.” It means that a pulse oximeter was used to determine the reading. This is important because you can also determine an accurate hemoglobin oxygen saturation by an invasive blood test called an ABG. It’s accurate because the percentage is taken directly from your blood. When saturation is determined using arterial blood, it’s referred to as SaO2. The “a” refers to “arterial blood.” The nice thing about pulse oximeters to determine an estimated SpO2 is that it is easy to do and does not require your blood to be drawn.

Pulse ox

This is an abbreviated way of saying pulse oximeter or pulse oximetry.

Pulse oximetry

Using a pulse oximeter to measure oxygen saturation (SpO2).


It’s a display on the surface of the pulse oximeter. It usually displays the SpO2 as a percentage. It also displays the heart rate. I think the values shown are usually in red.


Not enough oxygen making it to tissues. Your tissues need oxygen to do their work. So when they don’t receive enough oxygen this can stress cells out. This can cause damage to cells and tissues. So, our goal is to prevent this from happening. This is why your oxygen levels are monitored.


It means that arterial blood oxygen levels are low. When they get too low it can cause hypoxia. You want to make sure your tissues are getting enough oxygen. So, if your blood oxygen levels get too low, you may benefit from supplemental oxygen. Hypoxemia can be monitored by monitoring your oxygen levels. The simplest way of doing this is by using pulse oximetry.


SpO2 is so well accepted by doctors that it's now often referred to as the fifth vital sign. It's as easy as slipping a probe over your finger. It's so easy, and the technology has advanced so far, that you can even get small, handheld pulse oximeters for using at home.

Should you get a pulse oximeter?

So, you can see how pulse oximeters are nice. Modern ones can be held in the palm of your hand. You can even buy them at places like Walmart, Aldie, and Amazon for less than $25. If you do buy one, just make sure it’s FDA approved. The FDA approves the ones it deems to be accurate. Your doctor can help you determine if it’s a good idea for you to have available to monitor your own oxygen levels.

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