How to Interpret Pulse Oximeter Readings

Pulse Oximeter Advice

How to Interpret Pulse Oximeter Readings
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Pulse oximeters are simple devices and interpreting its reading is not really complicated. In fact, it’s quite simple. But in order to really understand the device you have to understand the human body and how it functions.

What is Oxygen Saturation

Oxygen saturation means blood molecules are carrying the maximum amount of oxygen possible. If every bit of hemoglobin is carrying oxygen, then we would have a blood oxygen saturation of 100%. A healthy person with normal lungs, breathing at normal altitude, should have an oxygen saturation level between 95 percent and 100 percent.

We know that our blood is red. But there is a bit of nuance involved here, and that’s how pulse oximeters measure our blood oxygen levels. When blood is in our arteries, it has a bright red color, whereas when it in our veins it has a dark red color. The difference in color is due to the amount of oxygen in hemoglobin. By the time blood travels from arteries to veins, it has dispersed some of the oxygen it had been carrying.

What Does a Pulse Oximeter Measure

A pulse oximeter measures two physiological aspects of our body. First is the oxygen saturation of hemoglobin and the pulse rate in beats per second.

As the amount of oxygen in hemoglobin decreases, the color of blood changes along with it. The change can be detected by a pulse oximeter using light sensors. The device flashes beams of light that can penetrate the skin and reach the blood. When the light is reflected back towards the device, it is picked up by the sensors. The device can interpret the reflection and determine the color of the blood.

The color of the blood can then be used to determine the level of oxygen saturation in our blood. And through the saturation of blood, the device can indirectly determine, with reasonable accuracy, the amount of oxygen carried by our blood.

The device also measures our heart rate per minute. The reason for measuring our heart rate is to determine the signal strength of the device. It allows us to know if the device is working properly or not. In the case of a weak signal, we would know that the readings could be inaccurate. It serves as a fail-safe mechanism to minimize the potential for incorrect readings.

How to Interpret Pulse Oximeter Readings

As you can see, there is not much for us to do when using a pulse oximeter. It functions on a dual process system that allows us to know if the device is working properly or not. Moreover, every pulse oximeter comes with an alarm, which alerts us when our blood oxygen levels fall below a certain level.

So even if you don’t understand how to interpret pulse oximeter readings, you can still use it effectively to monitor your blood oxygen levels. But it is still important to understand how to interpret pulse oximeter readers.

Normal Range for Pulse Oximeter Readings

For a healthy adult, a normal reading typically ranges between 95 and 100 percent. However, the same wouldn’t apply to individuals suffering from lung diseases such as chronic obstructive pulmonary disease. Although your physician will tell you what is normal for your specific condition, it is not uncommon for people suffering from lung diseases to maintain their pulse ox reading between 88 and 92 percent.

In the case of a healthy child, oxygen saturation levels tend to fluctuate between 96 and 100 percent. The range is similar to a healthy adult. But in the case of children, even a drop below 95% is a cause for concern and might result in a physician to order a medical intervention.

Conditions that May Yield Inaccurate Readings

It is extremely unlikely to have abnormally high blood oxygen levels. The only way high oxygen levels can occur is due to overuse of supplemental oxygen. This can only be detected using an arterial blood gas test, an invasive test for measuring blood oxygen levels.

There are some external interferences that can artificially yield low pulse ox readings. Strong and bright lights can affect the sensors’ ability to accurately measure our blood saturation level. Artificial nails and nail polish can also result in inaccurate and artificially low readings because it prevents light from penetrating through the extra layer.

How to Deal with Low Blood Oxygen Levels

Oxygen supplementation or oxygen therapy is the ideal way to boost oxygen saturation. However, oxygen supplementation is considered as a prescription medication, and your doctor must prescribe it.

A temporary drop in oxygen saturation is not believed to be harmful. But if your blood saturation continuously drops below normal levels, you will need to seek medical attention. Also, it important to follow your doctor’s advice when using oxygen therapy to avoid needless complications.


Now you should know how to interpret pulse oximeter readings. In fact, you should understand how the device functions, including the physiological aspects involved in the process. Before we end the article, a quick reminder, always remember to keep the alarm turned on.

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