Mammals can breathe through the anus in an emergency, Japanese study finds

A team of Japanese scientists showed in a study released on Friday that it was possible for mammals to absorb oxygen through ... their anus.

To discover

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Intrigued by the way some animals breathe through their intestines in an emergency, researchers at Tokyo Medical and Dental University have proven that the same is possible, under experimental conditions, in mice, rats and pigs. .

According to their work, published in the journal Med, this could also apply to humans in a state of respiratory distress, for example during a shortage of ventilators, as was the case during the Covid-19 pandemic, or when these machines do not prove to be suitable for a patient.

Breathing typically involves the inhalation of oxygen and the exhalation of carbon dioxide through the lungs or gills.

But species have developed other mechanisms.

Some fish, spiders, or even sea cucumbers, can use their posterior to get oxygen in order to survive in emergency situations.

A phenomenon designated by the English acronym EVA, which can be translated as enteric respiration via the anus.

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The rectum has a mesh of fine blood vessels just below the surface of its wall, which means that drugs delivered through the anus are easily absorbed into the bloodstream,

” says lead author Ryo Okabe. .

It is on this principle that suppositories are based.

So the team of scientists wondered if oxygen could be administered in the same way.

To demonstrate this, they decided to carry out experiments on mice, pigs, and rats lacking oxygen.

Two methods were tested: delivering oxygen in the form of gas, or by performing an enema rich in oxygen.

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Provocative idea

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Scientists in the first case prepared the walls of the rectum by friction, in order to cause inflammation and increase blood flow, which improves the efficiency of the delivery of oxygen. However, since such a treatment would not be accepted in humans, they also used an oxygen-enriched liquid, perfluorodecalin, which is known to be harmless. As a result, the oxygen delivered in both gas and liquid form increased oxygenation, normalized animal behavior, and extended their lifespan.

The researchers said the small amount of fluid absorbed along with oxygen caused no harmful effects and did not disrupt gut bacteria, indicating that the method was safe. Ultimately, they hope to prove the method's effectiveness in humans. “

Patients in respiratory distress could have their oxygen needs provided by this method while their disease is being treated,

” said one of the co-authors, Takanori Takebe.

In a commentary accompanying the study, Caleb Kelly of Yale University School of Medicine stressed that the technique should be taken seriously. "

It's a provocative idea and those who discover it for the first time will be surprised,

" he conceded. “

But considering the clinical role it can play and the data presented (by this study), VAS emerges as a promising therapy that deserves the interest of the scientific and medical community.

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