Pulse Oximeter SPO2 blood oxygen monitor measurement

Benefits of Using A Pulse Oximeter

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A pulse oximeter is a convenient portable device to measure the oxygen level in your blood and pulse rate. You may find this popularly used in hospitals and clinics for people suffering from respiratory diseases such as asthma, lungs disorders, heart diseases etc. It can be a helpful device for pilots, mountain climbers, athletes or anyone wanting to monitor blood oxygen and heart rate. Read on to learn more about mechanism, uses and benefits of a pulse oximeter…

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Pulse Oximeter Definition

A pulse oximeter is a device meant for non-invasive measurement of arterial blood oxygen saturation (SpO2) and pulse rate. You may notice that Oximeters are widely used in hospitals, clinics, operating rooms or ICUs. Both oxygen saturation level and pulse rate are vital signs of a person or a patient. Oximeters are handy, inexpensive and you can get accurate readings in seconds.

Pulse oximeters are useful if you have asthma, chronic obstructive pulmonary disease (COPD), chronic obstructive airway diseases (COAD) or other respiratory problems. Health experts suggest that people  with serious respiratory problems should get their SpO2 levels checked regularly.

Oxygen is life for you!

When you breathe, oxygen in the air enters your lungs. The oxygen then passes into your blood stream where majority of oxygen attaches to haemoglobin.  Haemoglobin a protein located inside your red blood cells. The oxygenated blood carrying protein then circulates to the tissues and keeps you healthy.

Hence, assessing your need for oxygen is an essential element of life; no human life can survive in the absence of oxygen. More so if you happen to suffer from respiratory or lungs disorders.

What is Pulse Oximetry?

Pulse oximetry refers to a test used to measure the oxygen level (oxygen saturation) of the blood. It is an easy, painless measure of how well oxygen is being sent to different parts of your body farthest from your heart, such as the arms and legs.

The finger-tip pulse oximeter is made with technology to quickly detect changes in your blood oxygen level. It indirectly monitors oxygen saturation blood, which is different from measuring oxygen saturation from a blood sample taken from your body. Pulse Oximeters are non-invasive, painless, and easy to use device for knowing efficiency of oxygen delivery to the tissues.

What is Oxygen Saturation in Pulse Oximetry?

A blood-oxygen monitor on a Pulse Oximeter displays the percentage of blood that is loaded with oxygen. Oxygen saturation is calculated as fraction of oxygen-saturated haemoglobin relative to total haemoglobin (unsaturated + saturated) in the blood.

What is meant by SpO2 – Pulse Oximeter Readings ?

The reading of SpO2 stands for peripheral oxygen saturation. This is not exactly same as SaO2, which refers to arterial oxygen saturation, which is determined from arterial blood gas analysis typically done in a clinic or hospital.

However, these two metrics are found to be well related to each other. As per research done at Santa Casa Hospital of Brazil, the fingertip pulse oximeter readings were found to have similar accuracy as the hospital oximeter fitted with a digital sensor. So SpO2 through pulse oximetry is a good indicator of oxygen saturation for regular use.

Nowadays, more and more doctors are prescribing this portable Pulse Oximeters for persons needing to continuously monitor SPO2 or heart rate. The main reasons : pulse oximeters are safe, convenient, easy to use, handy, non-invasive and inexpensive ! They are readily available online too!

What is the normal oxygen level (SpO2 level)?

Normal blood oxygen levels in us are considered to be 95–100 per cent. For people with mild or moderate respiratory (breathing related) problems, the SpO2 measurement should be 90% or above. If your oxygen level is going below 90 per cent, then it very low and is medically called hypoxemia.

In such cases, i.e. if SpO2 level falls below 90%, supplementary oxygen can be used. At this stage you may want to consult your doctor or a pulmonologist (doctor specialising in lung diseases or respiratory problems).

Pulse oximeter uses

Pulse Oximeters are used to measure oxygen levels (or oxygen saturation) in the blood in a lot of clinical situations such as surgery, procedures involving sedation (e.g., bronchoscopy), effectiveness of lung medications and person’s tolerance to high activity levels.

Other reasons may include some of the following:

  • Mechanical ventilation – use of a ventilator to support breathing
  • Sleep apnoea – periods of cessation of breathing during sleep
  • Medical conditions, such as heart attack, congestive heart failure, anaemia, lung cancer, asthma, or pneumonia

Pulse oximeter – how it works

Pulse oximeter technology uses light absorptive nature of haemoglobin and pulsating nature of blood flow in the arteries to determine oxygenation saturation in the blood. This is briefly explained below.

First of all, you should understand that there is a colour difference between haemoglobin saturated with oxygen, which is bright red AND haemoglobin without oxygen, which is darker. Oxygenated haemoglobin absorbs more infrared light and allows more red light to pass through, thus looking bright red. On the other hand, deoxygenated (having less oxygen) haemoglobin allows more infrared light to pass through and absorbs more red light, thereby looking darker.

The pulse oximeter compares how much red light and infra-red light are absorbed by the blood. The ratio of the amount of red light absorbed is then compared to the amount of infrared light absorbed and this difference indicates presence of certain amounts of oxygenated haemoglobin  and deoxygenated haemoglobin.

Advantages of using a pulse oximeter

  • Simplicity of use and the ability to provide continuous and immediate oxygen saturation values. Hence this can be used at home, at work or while exercising.
  • Portable battery-operated … Power source is not required. It can be used by pilots in non-pressurized aircraft above 10,000 feet where supplemental oxygen is required. Portable Pulse Oximeters can be used by mountain climbers or athletes whose oxygen levels may decrease at high altitudes or due to heavy exercise.

Some oximeters come with a software that can chart your blood oxygen and pulse, serving as a reminder to check blood oxygen levels.

  • Provides convenient non-invasive continuous measurement of blood oxygen … In contrast, blood gas (inlc. oxygen) levels are determined in a laboratory conditions on a blood sample taken from the body.

It is used by doctors for regular assessment of any patient’s oxygenation and heart rate. This can determine the effectiveness of or need for any supplemental oxygen. These devices are very useful if you have respiratory or cardiac problems, especially COPD, or for diagnosis of sleep disorders such as apnoea and hypopnea

What are the limitations of pulse oximeter?

The following are the main limitations of a pulse oximeter :-

  1. It cannot determine metabolism of oxygen, i.e. the amount of oxygen being used by the person.
  2. Pulse oximetry also is not a measure of circulatory sufficiency. If there is insufficient blood flow or insufficient haemoglobin in the blood (anaemia), tissues can still suffer hypoxia despite high oxygen saturation in the blood.
  3. Since pulse oximetry measures only percentage of “bound” haemoglobin, a falsely high or falsely low reading can occur even when haemoglobin binds to something other than oxygen.

When do I need to use pulse oximeter at home?

You can use a finger pulse oximeter to measure your oxygen saturation and/or heart rate level at any time, such as at home, at work or during recreation. This is such a convenient device to have.

In case advised by doctor, you can use pulse oximeter to help manage your supplemental oxygen requirements, manage asthma and other respiratory problems such as COPD. Your doctor may also prescribe the specific oxygen saturation target for you and the regular flow rate that should usually keep your oxygen saturation at that level.

People with serious cardiac condition would often experience low SpO2 levels. Pulse Oximeters can help them monitor their conditions and use supplementary oxygen when required.

Even if you are a normal healthy adult, you can use this to monitor heart rate and oxygen saturation during certain types of sports activities or high-altitude mountain activities. Pilots, mountain climbers and people in high altitudes thus can use pulse Oximeters to help them guard against hypoxia.

What are the ways to increase my blood oxygenation level ?

For many patients, doctors often recommend exercise to improve their physical stamina and overall fitness. However exercise can result in increasing shortness of breath. Patients should monitor their oxygen saturation with pulse oximeters while exercising so they can adjust the pace as the oxygen saturation decreases.

Proper breathing techniques, such as pursed lip breathing, can increase your oxygen saturation level. Studies suggest that many people with low oxygen saturation are able to increase their saturation up to 93% with good breathing techniques.


A pulse oximeter is a convenient, portable and easy to use personal health device to measure oxygen level in your blood and your pulse rate. While it is used in hospitals and clinics for people suffering from respiratory diseases, it can be a very helpful device if you require to monitor your blood oxygen and heart rate on regular basis. Pilots, mountain climbers and athletes can definitely benefit from its usage.





Disclaimer: This information / content published for educational purposes only and can by no means be considered fully exhaustive and complete. It should therefore not be used as a substitute for the medical advice and/or treatment by your healthcare provider.