An oximeter (illustration).

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  • Since their use has spread on a daily basis, in the midst of the Covid-19 pandemic, masks have been accused of causing a lack of oxygen, or hypoxia.

  • If many doctors have repeated in recent months that masks could not cause such effects, some parents are now measuring the level of oxygen saturation of their child's blood after school to prove this alleged impact. harmful to health.

  • Is this measurement, carried out using an oximeter, convincing?

    20 Minutes

    takes stock. 

What if the alleged health hazard of protective masks against Covid-19 could be proven by measuring the level of oxygen saturation in the blood using a simple oximeter, an over-the-counter device?

This is, in any case, the mission undertaken for a few weeks by many parents to denounce on Facebook hypoxia - a lack of oxygen supply - which their offspring would suffer because of the health protocol in force in schools.

“Today, in a pharmacy, I buy my oximeter to measure the oxygen level of children by illegally wearing a mask: a simple medical method that allows me to prove the dangerousness of wearing a mask for our children […] in order to to say NO!

"," Test with oximeter before and after school, 3 hours of mask category 1, result: 90. Hypoxia [begins] below 95 ", thus affirm two testimonies among others.

The initiative, far from being isolated, is encouraged by the association Réaction 19, whose president, Carlo Alberto Brusa, recently sent a letter to senators and deputies in which he is concerned about "measures obtained [which are] extremely shocking ":" The children all leave their homes with an oxygenation rate of between 97 and 100% and end up, when they leave school, with a rate often lower than 95%, and sometimes even lower than 90 %!

As a reminder, it is clear that the state of hypoxia is declared when the level of oxygenation in the blood is less than 95. "

Justified concerns or resolutely alarmist messages? 

20 Minutes

takes stock.

FAKE OFF

“We talk about hypoxia when the body is deprived of oxygen and it lacks it.

The reasons can be varied: the altitude, when one is at 1,000 meters or more, the fact of having the head under water… But also in the case of certain respiratory diseases preventing the lungs from absorbing water. oxygen ”, explains

Samuel Vergès, research director at Inserm (National Institute for Health and Medical Research) in the Hypoxia and physiopathologies laboratory at the University of Grenoble-Alpes

, to

20 Minutes

.

From the first months of the Covid-19 pandemic, protective masks have been accused of causing hypoxia ... wrongly, as detailed by a number of doctors questioned on the subject.

“A surgical or fabric mask allows oxygen to pass through.

The nursing teams, who wear FFP2 for several hours, would have realized it, if there was a problem at this level, ”explained in particular to

20 Minutes

 the pulmonologist Jean-Philippe Santoni last May.

A scientific finding corroborated by the WHO on its website: “Prolonged use of medical masks can be uncomfortable, but it does not lead to CO2 poisoning or lack of oxygen.

"

"When we have trouble breathing, our body alerts us"

If masks can indeed be painful to wear, especially for a long time, "they are made so that we can breathe through and be worn lengthwise without health concerns," recalls Samuel Vergès.

“On the other hand, if you put a plastic bag on your head, which prevents you from exchanging fresh air with the outside, there, yes, you will cause hypoxia.

When we have trouble breathing, we feel it very quickly because our body alerts us: headache, suffocation, etc. ”, adds the research director at Inserm.

“The normal blood oxygen saturation value is around 98%, not 100%.

When you climb to 1,500 or 2,000 meters in altitude, you will be at 95%, and at 2,600 or 3,000 meters, you are still below this percentage.

We are therefore in a condition of hypoxia but we do not fall ill for all that, ”continues the specialist.

A measure sensitive to a double bias

How, then, can we explain that children leaving school after a day of wearing the mask may end up with rates below 95%, depending on the oximeter placed at the end of one of their fingers?

Measuring the saturation rate "is very sensitive to a double bias: test and device conditions", explains Samuel Vergès.

“In particular, you have to make sure that it is done on a hand that is warm enough so that blood circulation takes place at the fingertips: if they are cold, the value necessarily drops.

You can take measurements on a child without a mask on leaving school and find a result lower than 95%, it is difficult to draw conclusions ”.

“This measurement must be done under standardized conditions and by a healthcare professional.

For the best oximeter models, we are on an accuracy of about 2%.

But on the others, it can turn between 3 and 4% so we are in a gray area, ”concludes the research director at Inserm.

Health

Coronavirus: Does prolonged use of the mask deprive of oxygen?

The answer is no !

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