Are Pulse Oximeters Accurate and How Do They Work?

Pulse Oximeter Advice

Are Pulse Oximeters Accurate and How Do They Work
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Pulse oximetry is a way through which we measure how much oxygen our blood is carrying. It is done through a small device known as the pulse oximeter. These devices are small and extremely useful but are pulse oximeters accurate? In this article, we will try to understand the device and see how accurate they are.

Pulse Oximeters

The best thing about these devices is that they can measure something as important as our blood oxygen levels without any needles or any other invasive methods. The device is fairly simple to use; you simply clip it to your finger, and it is able to measure your blood oxygen levels from the exterior of your skin.

In order to measure our blood oxygen levels, an oximeter measures something called the oxygen saturation level, also known as SaO2. This represents the percentage of how much oxygen is being carried by our blood relative to its maximum capacity of carrying blood. Normally, 89% of your blood should be carrying oxygen.

Importance of Pulse Oximeters

If you have some form of respiratory disease, your blood oxygen levels might be lower than normal. In such cases, it is important to be aware of your blood oxygen levels because a lack of oxygen in the blood supply can result in degradation of the body on a cellular level.

Oxygen is the fuel on which most of our bodily functions rely. Every breath of air to take goes into our lungs, where the oxygen is extracted and dissolved in our blood. Hemoglobin a form of protein in our blood carries the oxygen in our blood. As the blood circulates throughout the body, it delivers oxygen to each and every part of our body, feeding the cells the fuel it needs to function, repair and reproduce.

As mentioned earlier, you need at least 89% of your blood to be carrying oxygen in order to stay healthy. A temporary and brief decline in the blood oxygen level is not believed to cause any harm. However, persistently low oxygen levels in the blood can have a severe and lasting effect on our health.

This is why it is so important to use pulse oximeters to monitor our blood oxygen levels. If you regularly suffer from low blood oxygen levels, then you need to supplement through oxygen therapy or other means.

How Does a Pulse Oximeter Works

Pulse oximeters are available in two variants. You will find them as either a small unit that clips to your finger or toe or as a small handheld device with a wire that attaches to the finger, toe or earlobe. The smaller variant is more practical for home use and is quite economical as well.

The device works by flashing beams of light directly onto our skin, which can pass through the skin and blood. The reflection of the light is measured by the device and reflection can take the state of the blood and the oxygen it is carrying. The amount of oxygen in the blood can alter its color due to hemoglobin, which can change the color of our blood.

This is how the device measures how much oxygen is being carried by our blood. Moreover, the same technique can also provide a reading of our heart rate. If you count your pulse for one minute and compare it with the number you’re getting from the pulse oximeter, you can get a good idea of the signal quality, which also affects the accuracy of the device.

Are Pulse Oximeters Accurate

One of the most commonly asked questions is, are pulse oximeters accurate? Well, it is not a hundred percent, but it is reasonably accurate, more than enough to suffice for home use. Most oximeters have a margin of error of around 2 percent. Meaning, if the reading show 93 percent, the actual reading can be anywhere between 91 and 95 percent.

The quality and accuracy of the reading can be affected by a number of things. For example, if you’re wearing nail polish, the light from the device might not be able to penetrate as well and affect the accuracy of the result. Other than nail polish, artificial nails, cold hands, and poor circulation can affect the accuracy of a pulse oximeter reading.


Aside from the few things mentioned above, pulse oximeters are fairly accurate. It might not be as accurate as an arterial blood gas test but its accurate enough to be extremely useful.

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