An unexpected medical perspective is emerging from Japanese laboratories, where a rather unusual approach for oxygen administration has just reached a significant milestone. This method, inspired by biological mechanisms observed in nature, relies on using the intestinal walls as a gas exchange interface. The first clinical trials have just revealed the safety of this procedure in healthy volunteers, paving the way for potential therapeutic applications for patients in respiratory distress.
The underlying scientific concept, named enteral ventilation, could constitute an alternative to conventional respiratory support techniques. Its active principle uses a liquid with particular physicochemical properties, capable of binding significant amounts of oxygen. The therapeutic objective is to allow this vital gas to cross the rectal mucosa to reach the bloodstream, thus bypassing the upper airways when they become compromised.
Inspiration from the animal world
Several aquatic species have developed intestinal respiratory capabilities to survive in oxygen-poor environments. Loaches, freshwater fish, can thus swallow air at the surface and extract oxygen through their digestive tract. Some freshwater turtles also use their cloaca to perform gas exchange underwater. These observations provided researchers with serious leads to explore alternative respiratory pathways in mammals.
The human intestinal mucosa has anatomical characteristics favorable to this type of exchange. Thin and richly vascularized, it normally allows the absorption of nutrients and certain medications. Scientists hypothesized that this membrane could also allow oxygen molecules to diffuse toward blood capillaries. Previous work on porcine models had validated this principle, demonstrating the possibility of oxygenating blood through this unconventional route.
The liquid used in this research, perfluorodecalin, has an exceptional affinity for respiratory gases. This compound can dissolve up to fifty times more oxygen than water, thus creating a concentration gradient favorable to its passive diffusion through tissues. Already approved for certain medical uses, this product has the advantage of being biologically inert and not absorbed by the body.
First results in humans
The preliminary clinical trial included 27 healthy male volunteers. Participants received different amounts of non-oxygenated perfluorodecalin (between 0.25 and 1.5 liters), which had to be retained for 60 minutes in their rectum. This initial phase aimed exclusively to assess the local and systemic tolerance of the procedure, without measuring the effectiveness of gas exchange. The experimental protocol carefully increased the administered volumes to identify any potential adverse effects.
Among the participants, 20 tolerated the entire planned duration, including those who received the largest volumes. Clinical observations revealed no changes in vital parameters during the experiment. However, researchers noted the appearance of abdominal bloating sensations and discomfort in subjects receiving the largest volumes, without observing any severe adverse reactions.
The investigators emphasize the preliminary nature of these data in the pages of the journal
Med. They indicate that this first step only validates the safety aspect of the method in healthy subjects. Demonstrating its effectiveness in improving blood oxygenation will require additional investigations using the oxygenated version of the liquid. These results, however, open a promising path for the development of this therapeutic approach.
Article author: Cédric DEPOND