In 2021 a research group led by Tokyo Medical and Dental University (Japan) had proposed the ‘Enteral ventilation’ technique as an alternative to mechanical breathing via intubation, thus proposing “butt breathing”. Although it may make you laugh, over the years the technique has proven to be safe, and now, after the first experiment on humans, scientists believe it could be the future of emergency medicine.
The study, not surprisingly, has attracted the attention of Annals of Improbable Research who in 2024 awarded the authors of this work the IgNobel Prize for Physiology, which, like all IgNobels, is awarded to research that first makes you laugh (perhaps) but then reflect.
What researchers had really discovered in 2021
The scientists of Tokyo Medical and Dental University have shown that oxygen can be transported across the intestinal wall to compensate for the reduced availability of the crucial gas in the body, a condition that occurs in lung diseases that cause respiratory failure.
Breathing means living – the authors wrote – For higher animals, breathing involves the absorption of oxygen and the excretion of carbon dioxide through the gills or in the lungs. However, some species have developed alternative ventilation mechanisms: loaches, catfish, sea cucumbers and weaver spiders can absorb oxygen through the hindgut to survive in situations where oxygen availability is limited
And inspired by these unique adaptations, the team devised strategies to allow gas exchange across the intestinal mucosa, a process called enteral ventilation, or EVA.
The rectum has a network of thin blood vessels just beneath the surface of its mucosa, meaning that drugs administered through the anus are readily absorbed into the bloodstream,” explained Ryo Okabe, first author of the work. “This led us to ask whether oxygen could also be put into the bloodstream in the same way.”
The scientists, in particular, had tried to use oxygenated perfluorodecalin (PFD) in the laboratory, a liquid that can be used safely in the human body, already in selective clinical use, and which can transport large quantities of oxygen and carbon dioxide. The method, thus, proved to be potentially effective for patients with respiratory failure, increasing oxygenation levels, thus prolonging survival, with overall general safety.
Patients in respiratory distress can benefit from this method to support oxygen supply, reducing the negative effects of oxygen deprivation during the treatment of the underlying disease – argued Takanori Takebe, lead author of the research – Enteral ventilation has proven very promising in our asphyxia-like experimental model. The next steps will be to test the safety of the EVA approach with a deeper understanding of the working mechanisms and establish its efficacy in humans in a clinical context
This work was published on Cell.
What was discovered next (and what’s missing)
The Japanese researchers, at least about safety, were right: this year, in fact, the method was tested on humans for the first time, demonstrating the applicability of the technique in the absence of significant negative effects.
Specifically, 27 healthy male volunteers in Japan were instructed to hold between 25 and 1,500 milliliters of a non-oxygenated version of the liquid in their rectum for 60 minutes, and no serious adverse effects were reported, although participants who took the highest volumes experienced abdominal swelling, discomfort and pain. Other vital signs remained unchanged and only seven participants were unable to hold their “breath” for the entire hour.
This is the first data on humans and the results simply demonstrate the safety of the procedure and not its effectiveness – says Takanori Takebe now – But now that we have established tolerance, the next step will be to evaluate the effectiveness of the process in supplying oxygen to the bloodstream
The next study will then use the properly oxygenated version of the liquid and test the amount and duration needed to clinically improve a patient’s blood oxygen levels.
This latest research was published on Med.
Sources: Institute of Science Tokyo / Cell / ScienceAlert / Med
