Although a priori we have been taught from childhood that the lungs are the organ responsible for our breathingthe reality is that breathing through the ass is also possible. And it is not a theory, but rather it has been put into practice, as a clinical trial has shown published in the magazine Med who has named this technique enteric ventilation.
The current situation. When a person is in a critical condition, it is quite common to perform an intubation with the aim that a ventilator can do the action of exhaling and inhaling with the aim also of applying an extra dose of oxygen when there is respiratory depression or simply controlling this route. Although it is also a technique that can be seen in an operating room, in surgery, when anesthesia is applied.
The problem is that sometimes intubation is not possible, because the airway is very compromised or simply because the lung is in a state that prevents it from performing its normal function. This forces us to look for alternatives to maintain blood oxygenation, and one of them is this enteric ventilation through another area such as the rectal area, which is presented as support but not a substitute, but is a further advance in emergency medicine.
The technique. It has already been tested by the Takanori Takebe research team of the Cincinnati Children’s Hospital and the Osaka Universityis presented as a complementary oxygenation pathway in very serious respiratory emergencies. In Takebe’s own words“does not seek to replace mechanical ventilators or ECMO, but rather to offer a temporary means of support to allow the lungs to rest.”
The operation. The idea of breathing through the rectum was not born in the laboratory, but in an aquarium. In 2021, Takebe and his group they published in Med a pioneering study in which they demonstrated that animals such as mice, rats and pigs could survive low-oxygen environments if their intestines received oxygenated perfluorodecalin.
This liquid, a perfluorocarbon Chemically inert, it can transport oxygen in concentrations much higher than what an erythrocyte can do. And to test it, they introduced it through the rectum, causing the animals to reverse the lethal hypoxia and reduce the need to use the lung as a ‘pump’ to ventilate the body.
The administration was enteral, that is, through the rectum. In animal models, intestinal oxygenation managed to reverse lethal hypoxias and reduce the need for pulmonary ventilation.
The next step. Once tested on animals, the idea was to move on to humans and see if it was safe. To do this, they recruited 27 healthy volunteers who received one liter of perfluorodecalin not oxygenated by a controlled enema. In this case, none of them had hypoxemia and the goal was not to see if it could be reversed, but to check if they had any strange reaction. And the result was a success: there was only a little diarrhea (a good thing considering what could have happened).
But the most important thing is that the results coincided with what was observed in animal experiments, and above all they confirmed that there is no significant damage or inflammation in our intestinal mucosa.
What’s coming Takebe’s group is already planning a phase II clinical trial with patients suffering from moderate hypoxemia, in collaboration with hospitals in Japan and the United States. In this case, oxygenated PFD (O₂-PFD) will be used to determine if intestinal absorption can really raise blood oxygen levels as it occurs in animals, although expectations are very high.
If we look at the scientific literature, there are already different application possibilities. As published in Frontiers in Physiology in 2023 the potential of perfluorocarbons can be highlighted as alternative oxygen carriers, both for lungs with edema and for emergency medicine where it cannot be easily intubated or the lung is not 100% fit for it.
In parallel, the field of liquid ventilation has remained active among critics and intensivists: works such as the one published in Intensive Care Medicine Experimental in 2020, they pointed since oxygenated fluids could relieve pulmonary stress in patients with distress acute respiratory illness, serving as a “bridge” in life support therapies.
His comic side. In 2024, Takebe’s group received he Ig Nobel Prize for his research in enteric ventilation, an award that celebrates research that first makes you laugh and then makes you think. But, beyond humor, Takebe himself emphasizes that what began as a biological curiosity is giving rise to real biomedical innovation.
And although it remains to be confirmed that the human intestine can actually oxygenate blood effectively, accumulated data in animals and the first safety trials put enteric ventilation on the border between experimental biomedicine and advanced critical medicine.
Far from being an extravagance, research in liquid oxygenation is part of a growing area that seeks alternatives to invasive mechanical ventilation, especially in situations where resources or time are limited. And if all goes well, in the future a treatment that today sounds unthinkable—injecting liquid oxygen through the intestine—could become another tool in the arsenal of intensive care units.
Images | Alexey Elfimov
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