How to Read a Pulse Oximeter: Understanding Your Device

Pulse Oximeter Advice

How to Read a Pulse Oximeter Understanding Your Device
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A pulse oximeter is a medical device that is used for measuring the amount of oxygen in our blood. It is a noninvasive method for measuring blood oxygen levels. The device does this by measuring the oxygen saturation in the blood to indirectly measure the oxygen levels in the blood. In this article, we will address a very common question, how to read a pulse oximeter.

How Does a Pulse Oximeter Works?

As mentioned earlier, oximeters indirectly measure blood-oxygen levels by measuring the saturation of oxygen in the blood, which is also known as SpO2. Okay, so what is SpO2? SpO2 is a metric used for measuring the amount of hemoglobin in the blood that contains oxygen.

Hemoglobin is a protein found in our blood. It is the primary protein that carries oxygen in the blood. It is also the element that gives our blood its color. But more importantly, its color can change depending on the amount oxygen in the blood.

Pulse oximeters can detect changes in the color of our blood using non-invasive sensors. Changes in the amount of hemoglobin can affect the color of our blood, which can be measured by pulse oximeters and help us indirectly figure out the amount of oxygen in our blood.

Understand Your Pulse Oximeter Device

Now that we know what a pulse oximeter is, let’s look at the device and try to understand the various different readings it provides.

  • Step One: Understand the Device

The first thing you will do is find the SpO2 reading. You will find it on the digital readout panel. You will find the figures in percentage terms, usually between 92 and 99 percent. The exact location of the readout panel depends on the brand and type of the oximeter.

Some oximeters also display signal strength, which indicates the strength or intensity of the signal. A high signal would provide more accurate readings, while a weak signal is more prone to errors.

Most people have a SpO2 reading between 90 and 99 percent. Levels below 90 percent are unlikely as it indicates acute respiratory failure. However, some individuals who suffer from chronic respiratory diseases tend to have a blood oxygen concentration level below 90 percent without actually suffering from acute respiratory failure.

  • Step Two: Identify the Pulse Rate

Pulse oximeter devices, in addition to oxygen saturation, also measure pulse rate. Hence, you will also need to identify the pulse rate. The pulse rate is usually displayed as two or three digit numbers. It usually ranges between 60 and 100 and can be higher in children and infants.

  • Step Three: Secondary Measurements

There are certain pulse oximeters, such as the Zoll’s R-series, which also provide readings for plethysmogram and ECG. An ECG measures electrical activity that is generated by the heart. It is used for monitoring cardiac functioning and is helpful in identifying arrhythmias. On the other hand, plethysmography measures the changes in the blood oxygen level with each pulse.

A Few Precautions to Keep in Mind

First of all, many pulse oximeters have different settings for how it shows the readings. These settings can be changed at home but you shouldn’t. Doing so can result in inaccurate readings and distort the point of using the device. Unless your doctor says so, it’s better just to leave it as it is.

Another important thing to remember, these devices have alarms which can be a bit annoying, a reason why a lot of people tend to silence it. However, it is a good idea to get used to it as it will alert you when your blood oxygen levels or heart rate fall below the expected levels.

How to Read a Pulse Oximeter

For most healthy adults, an O2 sat of 95% is considered normal, while it’s between 96-100% for kids breathing room air. Around 89 percent of our blood cells should be infused with oxygen. This is the bare minimum necessary to keep our cells and body healthy. A temporary decline in oxygen levels is not believed to cause lasting damage. However, consistently low levels may be harmful and a cause for concern. 

This is basically all you need to know to read a pulse oximeter. In the event that your blood oxygen levels fall beyond the point of concern, the device will alert you, and in such cases, you should seek immediate medical attention.


Hopefully, you should now understand what pulse oximeters are and how they work. You should also be able to read and understand the device.

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