Pigs can breathe oxygen via their rectum, so humans probably can too

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Piping an oxygen-rich liquid through the anus could be a life-saver. A new treatment for failing lungs that involves such a process has been successfully tested in pigs.

People with low blood oxygen levels may be treated in intensive care by being put on a ventilator, which blows air into their lungs. But this usually requires sedation and can injure delicate lung tissue. “It can be really damaging,” says Takanori Takebe at the Tokyo Medical and Dental University.

Takebe wondered if people could absorb oxygen through their intestines, which happens in some freshwater fish. In mammals, the rectum is lined with a thin membrane that allows absorption of certain compounds into the bloodstream, and doctors already exploit this by giving some medicines as suppositories.

Takebe’s team tested the idea on pigs by giving them enemas of a type of fluid called a perfluorocarbon, which can hold high levels of oxygen. Such fluids have been investigated as a way of breathing liquid, and are already used to help protect the lungs of premature babies, so are likely to be non-toxic when used in this novel way, says Takebe.

The researchers anaesthetised four pigs and put them on a ventilator that gave them a lower breathing rate than normal, so their blood oxygen levels fell. When they gave two of the pigs enemas of the oxygenated fluid, replaced once an hour, their blood oxygen levels rose significantly after each infusion. The same effect happened when the fluid was delivered by a tube surgically inserted into the rectums of the other two pigs.

Read more: Divers could breathe deep with liquid-filled lungs

If there is a similar-sized effect in people, it would be enough to provide a medical benefit, says Takebe. He thinks the approach could be especially useful in low-income countries that have fewer intensive care facilities. “Ventilators are super-expensive and need a number of medical staff to manage,” he says. “This is just a simple enema.”

One problem is that gut function may be impaired in people sick enough to need intensive care, which can cause diarrhoea, says Stephen Brett at Imperial College London. “It’s too early to say if this has got any legs,” he says.

“This is a provocative idea and those first encountering it will express astonishment,” wrote Caleb Kelly at Yale School of Medicine in an article accompanying the paper. But the idea of faecal transplants for people with recurrent intestinal infections also met initial resistance for “aesthetic reasons” yet is now accepted, he added.

Read more: https://www.newscientist.com/article/2277532-pigs-can-breathe-oxygen-via-their-rectum-so-humans-probably-can-too/#ixzz6v97qt2AW