From Parody to Practice: Rectal Oxygenation Challenges Respiratory Medicine

This could have remained a simple scientific curiosity, relegated to the margins of medical research. However, this improbable idea of ​​passing oxygen through the intestines rather than the lungs has resisted ridicule and has just reached a decisive milestone. Enteral respiration, a method as surprising as it is promising, is moving closer to potential clinical use after a conclusive trial conducted on human volunteers.

From scientific curiosity to human experimentation

At the origin of this disconcerting approach, there is a fish. The loach, a species living in oxygen-poor waters, is able to supplement its respiration by absorbing air through its intestines. Fascinated by this adaptation, Japanese and American researchers sought to transpose the mechanism to humans. The idea is to use the rectum as an alternative route to get oxygen into the blood, especially when the lungs are out of commission.

The project was first rewarded with an Ig Nobel in 2024. This prize recognizes research that surprises as much as it questions. However, this touch of irony did not slow down the team of Dr. Takanori Takebe, a researcher in Osaka and at the Cincinnati Children's Hospital. Their objective remained very serious. They are looking for a way to help patients in respiratory distress when traditional treatments fail or worsen the lungs.

First of all, it was necessary to demonstrate that this procedure was not dangerous. The concept is based on the introduction into the rectum of a liquid capable of transporting large quantities of oxygen: perfluorodecalin. This substance, already used in medicine, has exceptional gas solubility properties. In 2021, a first study on pigs showed that part of the oxygen could pass into the blood circulation via this intestinal route. It remained to verify tolerance in humans.

© Cincinnati Children's Hospital

An innovative respiratory bridge in emergency situations: The perfluorinated liquid, administered rectally, could temporarily support oxygenation in the event of pulmonary distress.

Enteral respiration enters the clinical phase

In October 2025, the bet became reality. Twenty-seven Japanese men aged 20 to 45 took part in a pioneering clinical trial, the results of which were published in the journal Med. Volunteers received up to 1.5 liters of non-oxygenated perfluorodecalin, administered rectally. The solution had to be held for sixty minutes, without mechanical assistance.

Of the twenty-seven participants, twenty managed to keep the liquid for the expected duration. No serious side effects were noted. The most common symptoms were simple bloating or temporary abdominal discomfort. Biological analyzes confirmed the absence of abnormalities in liver and kidney functions, and no significant trace of fluid in the blood was detected.

As noted in the report published by Cincinnati Children's Hospital, this study marks an important milestone. It validates the safety and feasibility of enteral respiration in humans. This is not yet proof of effectiveness, since the liquid used was not enriched with oxygen. However, a predictive model based on animal data suggests that oxygenation could indeed occur with the appropriate version of the liquid.

Towards an alternative in case of respiratory distress

This advance opens new avenues for emergency medicine. Indeed, some patients cannot be ventilated without risk. In the event of an accident or acute inflammation, each respiratory intervention can worsen the situation. However, enteral respiration could serve as a temporary vital relay. It would buy time until the lungs resume their function or the airways are cleared.

The idea is not to completely replace mechanical ventilation, but to supplement it or delay it. It could also be beneficial in premature newborns, who are often fragile in the face of attacks from invasive respiratory systems.

According to New Atlas, the logical continuation is already underway. The researchers plan to test this time a version of the liquid enriched with oxygen, in order to evaluate its real effectiveness in raising blood oxygen levels. If the results are conclusive, this technique could join the medical arsenal in the years to come. In less than two years, a mocked idea is becoming a credible backup solution to save lives when the air no longer passes.