Scientists from Japan and the United States recently completed the world's first human trial of "Enteral ventilation" (anal oxygen inhalation), paving the way for an unconventional new oxygen delivery technology for patients with severe respiratory failure. This research team, which previously won the 2024 IgNobel Prize for the discovery that mammals can breathe through the anus, has initially confirmed the safety and tolerability of this technology in human experiments.
The clinical trial was conducted in Japan, and the subjects were 27 healthy adult men. During the study, volunteers were required to inject up to 1,500 ml of oxygen-rich liquid (unoxygenated perfluorodecane) through the anus and retain it in the body for 60 minutes. The scientific research team evaluated safety and tolerability by observing data such as adverse events, vital signs, clinical laboratory examinations, and systemic drug exposure, and used large animal data models to predict oxygen transport effects. Perfluorodecane was chosen because of its excellent oxygen-carrying capacity.
Among them, 20 subjects successfully retained fluid for 60 minutes. Even at the maximum injection volume, there were only mild side effects such as abdominal distension and discomfort, and all clinical indicators such as liver and kidney remained within the normal range. The researchers noted that this "first human study demonstrates that enteral injection of unoxygenated perfluorodecane is safe, feasible, and well tolerated. The results lay an important foundation for the subsequent technical development of using oxygen-rich fluids to support patients with respiratory failure."
The technology is inspired by a bottom-dwelling fish that swallows air to obtain oxygen through its intestines to assist the function of its gills when the water quality is poor. If humans could safely absorb oxygen-rich fluids through the colon and into the bloodstream, it could potentially save the lives of patients whose airways are blocked due to injury, inflammation or severely compromised lung function.
The research team next plans to conduct related experiments again to determine the amount and retention time of fluid required to increase blood oxygen levels.
Relevant research has been published in Med, a journal of Cell Press.