When pressed for oxygen, some fish and sea cucumbers will use their lower intestines to draw a little more from their surroundings. Now, a team of Japanese researchers say mammals are also able to breathe through their rectal cavities, at least in a lab.
The team’s research is published today in the journal Med and describes the ability of mice, rats and pigs to survive longer and have more strength under low oxygen circumstances when given either gaseous or liquid oxygen rich in oxygen through the rectum, in a process similar to an enema. While fish like groupers and catfish use a similar method to gain supplemental oxygen in the natural world, this does not appear to be an evolutionary adaptation for mammals. In other words, mammalian bodies can’t do this naturally, but with a little help from modern science it becomes possible. Previous research has seen oxygen injected directly into the bloodstream of mammals, extend the life of rabbits, but the rectal approach to the problem of low oxygen is new.
The experiment, while disturbing, was designed to find new ways to save the lives of people with failing lungs.
“Artificial respiratory support plays an essential role in the clinical management of respiratory failure due to serious illnesses such as pneumonia or acute respiratory distress syndrome,” said Takanori Takebe, gastroenterologist at the Tokyo Medical and Dental University and Cincinnati Children’s Hospital Medical Center, and lead author of the article, in a Press release. “Although side effects and safety must be carefully evaluated in humans, our approach may offer a new paradigm for supporting critically ill patients with respiratory failure.”
These treatments prolonged the survival of the animals in an oxygen-poor environment by preventing respiratory failure. Mice received both the gaseous and liquid oxygen delivery methods, while rats and pigs received only the liquid treatment.
In a controlled hypoxic laboratory environment (a 9.5% oxygenated chamber), mice without supplemental oxygenation died after approximately 11 minutes. With the treatment, three-quarters of the mice tested survived for almost an hour under the same lethal conditions. Gaseous oxygen ventilation required abrasion of the intestinal mucosa of the animals so that oxygen could enter the bloodstream. Because of this abrasive element, researchers do not expect gas ventilation to be clinically feasible in humans. To overcome this limitation, they used an oxygenated perfluorochemical which is safe for humans and can likewise carry oxygen in the bloodstream.
Pigs, mice and rats were injected rectally with the oxygen-rich liquid. The mice that received the treatment walked further and more oxygen reached their hearts. In pigs, the color returned to the skin of the animals, which also warmed up, and their oxygen levels improved.
“It’s a provocative idea and those who encounter it for the first time will express their astonishment,” Caleb Kelly, gastroenterologist at Yale School of Medicine, and who was not affiliated with the recent article, said in a document. accompanying Point of view article. “Yet while the potential clinical role is taken into account and the data presented by Okabe et al. is examined, EVA [enteral ventilation via anus] appears as a promising therapy which deserves scientific and medical interest. “
Researchers noted the shortage of ventilators for patients with covid-19 in the darkest days of the pandemic, which is raging in India and elsewhere. Another way to deliver oxygen to critically ill patients could save lives if it gives doctors enough time to tackle the cause of a person’s respiratory failure.
“Many procedures that are currently used in intensive care (and to save lives) could be considered more invasive than VAS,” Kelly said in an email to Gizmodo. “I am both skeptical and optimistic. EVA needs further study to determine if it will be effective and safe, but the concept is exciting. “