Blood Oxygen Level: Normal, Importance, Measurement, Variation, Levels, COVID19, And Test

Oxygen is required for life. In the atmosphere, there is 21% oxygen, which we inhale and use for all cellular functions of the body. That is why we are called aerobic organisms.

Importance of Oxygen

Oxygen is a wonder gas. It is required by the cell to extract energy out of the food we eat. But it’s role is not limited to energy production, it is also required to fight against many toxic substances and microorganisms ( bacteria, fungi, parasites) by the white blood cells. It has a role in the repair of damaged cells, in metabolising fat of the body and in many senses like vision, touch, hearing, smell etc.

Transport of Oxygen

Air inhaled by us first enters the respiratory systems, which consists of lungs mainly. In the lungs, we have many small units which extract oxygen and give it to blood. These are called alveoli.

In blood, oxygen binds to haemoglobin which is present in red blood corpuscles and gets transported to various organs by pumping of blood via the heart.

At the organ level, the oxygen detached from haemoglobin enters cells by simple diffusion.

Blood Oxygen Level Measurement

In blood, 98% is bound to haemoglobin, and the rest is transported in the dissolved form in plasma.

So, what we can measure is either dissolved oxygen or the haemoglobin bound oxygen. Dissolved oxygen levels in the blood are called partial pressure of oxygen. Normally, it is 95mm of Hg.

But the bound form is measured as haemoglobin saturation which is usually 98%.

Variations in Children

The arterial partial pressure of oxygen in a new-born baby is 75mm of Hg usually, and it gradually increases over a period of five years to reach adult level of 95mm of Hg.

Haemoglobin saturation of oxygen at the time of birth is 60%, it becomes 80% by 3 to 5 minutes of life and reaches more than 95% within 10 minutes.

The venous partial pressure of oxygen usually stays the same at 40 to 50 mm oh Hg throughout life.

How to Improve Blood Oxygen Level

Many people living in cities, breathing polluted air are suffering from respiratory illnesses like asthma, pneumoconiosis etc. which in the long term decreases their respiratory reserve causing an increase in carbon dioxide levels of blood and reduced oxygen levels. An easy way to combat this problem is by going to more green areas like parks nearby for walking and doing breathing exercises ( like Pranayama) there. Further, wearing masks like N90 or N95 purifies the air we inhale and prevents further lung damage.

Blood Oxygen Level in Athletes

Athletes have a better oxygen reserve than non-athletic persons. Due to their healthy lifestyle, the haemoglobin level in their blood is high, so quantitatively oxygen level also increases.

Regular exercise stimulates the synthesis of erythropoietin hormone, which increases the red blood cell count as well as haemoglobin in our body and improves oxygen reserve. Apart from this, it also boosts proper usage of oxygen by muscles which prevents early fatigue and keeps our body fit for a longer time. Yoga is one of the best ways to improve oxygen levels. It involves proper integration of breath with movements of the body which improves the activity of lungs along with purifying blood.

Blood Oxygen in Chronicle Respiratory Diseases

These days, a lot of people are suffering from chronic respiratory illnesses like asthma, interstitial lung disease, COPD etc. All these diseases have two common attribute factors – pollution of atmosphere and smoking habits.

In all of these, the lungs undergo degeneration, so they are not able to filter out carbon dioxide. This increases blood carbon dioxide levels which further cause hydrogen ion production, leading to an acidic environment in the blood. This impairs the delivery of oxygen to the tissues by haemoglobin, leading to deficiency of oxygen at the cell and tissue level. It is termed as hypoxia. This creates air hunger in the body and in the long run, even leads to heart failure and infections like pneumonia.

Blood Oxygen and Covid - 19 Infection

Covid – 19, a coronavirus which has turned into a dreaded pandemic is a unique virus with the ability to infect almost any system of the body. One of the most common areas it affects is lungs and bone marrow. In the lungs, it causes pneumonia in which lungs get filled with exudate and also impairs gaseous exchange. So, oxygen levels fall in blood and oxygen therapy is often used.

Blood Oxygen Level Test

It can be easily measured using an oximeter. Oximeter work on a simple principle of wave absorptiometry ( spectrometry), in which, two waves one of infrared and other of red light are passed. A chemistry law ( Baer’s Law) states that the amount of light absorbed of different wavelengths is different for different substances.
So, the infrared light is absorbed more by deoxygenated haemoglobin while the red light is absorbed more by oxygenated haemoglobin. Hence, we get to know the amount of oxygen bound to haemoglobin by this method. This is a very simple instrument which doesn’t involve the drawing of blood. It can even be used at home, one just has to put it on a finger for a few seconds, and it gives the values required. Just make sure you don’t have nail polish while measuring ( since it can give wrong results).

Smoking Affects Blood Oxygen

We all know smoking is harmful; still it remains the most common substance of abuse. Whether people are educated or not, they still believe in the myth that smoking is cool!

Well, it is not so cool for our body. It affects not only the lungs but also our brain and heart. To start with, smoking decreases the defences of the respiratory tract leading to frequent viral infections ( common cold and cough) and increases chances of pneumonia. It then starts interfering with the debris removal system, so the air which was usually filtered in nose and pharynx goes as it is to lungs and deposits dust there. Further, it causes fibrosis of lungs where the alveoli are replaced by long strands of protein just like a sieve in which tea leaves get stuck. This causes decreased exchange of air and lowers blood oxygen level.

Moreover, while smoking harmful gases like carbon dioxide and carbon monoxide are produced which enter the blood. Carbon monoxide is a dangerous gas that binds to haemoglobin in place of oxygen and impairs the oxygen-carrying capacity of the blood.

Blood Oxygen Level in Anaemia

In anaemia, the haemoglobin levels decrease so, logically, blood oxygen also decreases. But what we measure is the saturation of haemoglobin, so this remains normal even though the absolute amount of oxygen carried by the blood is low. So, a person with anaemia has a deficiency of oxygen and becomes breathless.

Blood Oxygen With Appliances

Most of the people are in the habit of sleeping with AC/ heaters on and closing all the doors and windows of the room. Even though this gives a cosy feeling, but it definitely hampers health in the long term. This is because the closed room has no connection with outer air which depletes the oxygen inside the room and so decreases blood oxygen levels. The functioning of sleeping brain is affected, which can cause fatigue next morning, increased day time sleepiness and cognitive impairment in the long term.

Blood Oxygen and Snoring

Snoring has become rampant these days as a result of increasing obesity. Well, when we snore, it means that airway is blocked partially, so our oxygen levels decrease and again brain functioning is affected. This not only decreases the quality of sleep but also leads to hypertension in the long run.

Conclusion

Oxygen is an inevitable requirement of life. We need 192 litres of oxygen per day! ( which is much more than the water we take in a month!). So, take care of your oxygen by exercising every day and spreading as much greenery as possible.

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Co-author: Paridhi Singhal

Paridhi is a budding doctor. Apart from studying medicine, she is a a keen writer who believes in the thought that pen is mightier than the sword.