Home WelfareGeneral well-being What is the pulse oximeter for and how to read it

What is the pulse oximeter for and how to read it

by Alivia Nyhan
Published: Last Updated on
pulse oximeter

Have you been suggested to buy or have you read about pulse oximeters? Do you want to know how useful it would be to have one in your home? Oximeters are small devices widely used in daily medical practice, as they provide information about the amount of oxygen in the blood and the frequency of the pulsations.

Next, in this FastlyHealarticle, we only offer you all the information you need to know about the pulse oximeter: what it is, what it is for, how it works, how to use it correctly, the keys to read it and know when it can give wrong results.

How does oxygen travel from the lungs to the rest of the body?

To understand what an oximeter is for and how it works, knowing what happens to oxygen is essential.

Oxygen is a gas that is present in the air we breathe, in greater or lesser concentration, depending on where we are, how high we are, and whether there is exposure to environmental pollution, among other things. An exchange occurs once it enters the lungs: oxygen enters the blood, and carbon dioxide leaves the lungs.

Oxygen is necessary for the proper functioning of each of the body’s cells. On the other hand, carbon dioxide results from the processes that occur in them and must be eliminated on expiration.

Once oxygen passes into the blood, it binds to hemoglobin in red blood cells (blood cells). Hemoglobin is a protein that has several functions, including transporting oxygen molecules throughout the body.

Not all hemoglobin in arterial blood is bound to oxygen. Typically, about 95% of it is called oxygenated hemoglobin or oxyhemoglobin, while the percentage of hemoglobin without oxygen is called deoxyhemoglobin or reduced hemoglobin.

What is a pulse oximeter?

A pulse oximeter is a small device that has two functions :

  • Measure the amount (saturation) of oxygen present in the hemoglobin of the arteries (known as SpO2).
  • Know the pulse and heart rate.

To achieve these functions, it uses red and infrared light detectors. Oxygenated hemoglobin absorbs infrared light and lets red light through. Instead, hemoglobin without oxygen does the opposite: it absorbs red light and not infrared.

These detectors are placed hugging an area of ​​translucent skin, which is why they are usually chosen:

  • Fingertip.
  • Pinna of the ears.
  • Foot or hand in young children.

Thus, both the number of beats per minute (pulse and heart rate) and the amount of red and infrared light are measured during an arterial pulse.

With these data, it is possible to estimate the amount of oxygen entering the body and circulating through the arteries to the tissues. On the small screen, these two pieces of information are displayed. They are an average of the last 3 to 6 seconds.

How to use and read an oximeter?

The pulse oximeter can give you interesting information if you know how to use it correctly:

  1. Before you start, you need to make sure your battery is charged.
  2. Place the oximeter in one indicated area (fingertip or earlobe).
  3. Wait for the result to be returned.

As we have seen, an oximeter measures two parameters. Both will be displayed on the small screen:

  • Heart rate/pulsations: varies between different people according to many parameters. Generally, between 60 and 100 beats per minute (bpm) or beats per minute (bpm) are expected.
  • This number can often be seen with the acronym bpm, bpm, or a tiny beating heart.
  • Oxygen saturation in arterial hemoglobin (SpO2): normality will depend on many factors. One of the most important in height above sea level measured in meters (masl) at which the person tested is. Regular at sea level (0 masl) is that SpO2 is 97-99%, but up to 94% is considered normal. On the other hand, at 2,500 meters above sea level, a healthy person can have between 85 and 87% SpO2

Pulse oximeter device

What factors influence the performance of an oximeter?

Different issues can modify the correct operation of an oximeter, including:

  • Movement: if the person moves during the oxygen saturation measurement, the results may be altered. It is important to remain very still while using this appliance.
  • Low blood circulation: In cases of shock, hypothermia, or people who received a recent transfusion, there may be less circulating arterial blood or blood pressure. Therefore, the results can be unreliable.
  • Pigmentation of the skin or nails: darker skins and the use of enamels tend to interfere a little with the measurement, so the values ​​may not be entirely reliable.
  • Electromagnetic interference: cell phones or other devices that could cause this type of problem can also alter the signal of the oximeter.
  • Ambient Light Interference – Solid white light can also affect its performance. The oximeter can be covered so that it does not receive as much light.
  • Diseases with hemoglobin disorders: they can give errors in the census.

For all these reasons, it is considered that constant measurement with an oximeter in stable people is unnecessary since there are many errors independent of the good use of the device. It is more than essential to consider the person’s symptoms more than the mere information that a device provides.

What is the pulse oximeter for?

After understanding how the oximeter works and how to use it correctly, it is necessary to know what it provides.

Knowing the oxygen saturation is a tool that allows inferring mainly how much oxygen is entering the body through the lungs, which is very useful in medical practice to decide treatments or know the state of a patient who has shortness of breath.

As we have seen, in some everyday situations, the amount of oxygen can be less and still be normal. This is the case of people who live in height.

Likewise, acute and chronic diseases can cause less oxygen to enter the lung than necessary. Lung infections ( acute bronchitispneumonia ), chronic diseases such as Chronic Obstructive Pulmonary Disease (COPD)lung cancer, fibrosis, among other processes, can cause lower SpO2.

Usually, a person with oxygen levels below normal feels short of breath. Therefore, it is necessary not to isolate just one result from the oximeter. If the oximeter reads 70%, but the person feels fine, it is likely a measurement error. Therefore, oximeter measurement in healthy, symptom-free people can satisfy curiosity but is not usually necessary.

However, it is useful when oxygen levels are deficient and feel short of breath. In that case, the person may require the supply of extra oxygen.

This article is merely informative. At FastlyHeal .com, we do not have the power to prescribe medical treatments or make any diagnosis. We invite you to see a doctor in the case of presenting any condition or discomfort.

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