Rectal Oxygenation: Scientists Explore Novel Approach to Respiratory Failure Treatment
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A groundbreaking study published in Med in Febuary 2025 demonstrates the safety of delivering liquid oxygen via the rectum,a procedure dubbed extra-corporeal visceral aeriation (EVA),offering a potential new avenue for treating severe respiratory distress. While initially met with an Ig Nobel Prize in 2021 for animal trials, researchers are now cautiously optimistic about its potential submission in human patients.
Patients with severe respiratory failure often rely on mechanical ventilation, a life-saving intervention that can, paradoxically, cause further lung damage. This new research suggests EVA could offer a respite, allowing the lungs to “rest and heal,” as one author explained.
from Animals to humans: A History of rectal Oxygenation
The concept of delivering oxygen rectally isn’t new. Initial experiments, which earned the research team an Ig Nobel Prize, involved administering oxygen gas or a liquid oxygenated perfluorocarbon to rodents and porcines via intra-anal administration. The results were surprisingly effective in mitigating respiratory failure in the animals, with no major complications observed.
Building on this success, the team initiated a human trial to assess the safety of the procedure. Twenty-seven healthy adult men in Japan participated in the study, each receiving a gradually increasing dose of non-oxygenated perfluorodecalin – ranging from 25 to 1,500 mL – administered rectally.
Initial Human trials show Promise,But Caution Remains
Twenty of the 27 participants successfully completed the hour-long retention period.The study revealed that the procedure was largely well-tolerated, with participants reporting only mild, temporary abdominal bloating and discomfort. These side effects were found to be directly related to dosage and resolved without any need for medical intervention.
“this is the first human data and the results are limited solely to demonstrating the safety of the procedure and not its effectiveness,” stated co-author Takanori Takebe of Cincinnati Children’s Hospital and the University of osaka in Japan. “But now that we have established tolerance, the next step will be to evaluate how effective the process is for delivering oxygen to the bloodstream.”
The researchers emphasize that this initial study focuses solely on safety. Further investigation is needed to determine whether EVA can effectively deliver sufficient oxygen to the bloodstream to improve outcomes for patients experiencing respiratory failure.
This research represents a bold, if unconventional, step toward addressing a critical medical challenge. While the idea of rectal oxygenation may raise eyebrows, the initial findings suggest it warrants further exploration as a potential adjunct therapy for those battling severe respiratory illness.
DOI: 10.1016/j.medj.2025.100887
Why: Researchers are exploring rectal oxygenation (EVA) as a potential option or supplement to mechanical ventilation for patients with severe respiratory failure, which can sometimes cause further lung damage.
Who: The study was conducted by a team led by researchers from Cincinnati Children’s Hospital and the University of Osaka in Japan, with co-author Takanori Takebe.Twenty-seven healthy adult men in Japan participated in the initial human trial.
What: The study demonstrated the safety of administering non-oxygenated perfluorodecalin rectally to humans. Participants tolerated the procedure with only mild,temporary side effects. The research builds on previous triumphant animal trials that earned the team an Ig Nobel Prize.
how did it end?: The initial phase of the research concluded by establishing the safety and tolerability of the procedure in humans. Researchers are now planning further studies to
