Having serious respiratory problems? You may soon be able to breathe from the ‘other end’

A novel medical technique called enteral ventilation has raised eyebrows — and hope — in the world of respiratory care for patients whose lungs are severely compromised. Oxygen delivered through the digestive tract rather than the lungs may sound strange. But the science behind it is advancing.

What is intestinal oxygen delivery?

Enteral ventilation, often nicknamed “b—t breathing,” is the process of delivering oxygen-rich liquid or gas into the intestines, usually through the rectum, so that oxygen can enter the bloodstream directly. Blood vessels fill the lower gut, and under the right conditions, it can absorb gases much like the lungs do. According to scientists, medical staff could use this in emergencies when a patient’s lungs sustain damage or are failing.

In 2024, enteral ventilation won an Ig Nobel Prize in physiology, the tongue-in-cheek award that celebrates research “that first makes people laugh, then makes them think.” The winning team, led by Japanese scientist Takanori Takebe, received honors for the groundbreaking discovery that mammals can breathe through their intestines under certain conditions.

How does enteral ventilation work?

Normally, oxygen enters the body through the lungs and diffuses into the blood. Enteral ventilation works by bypassing the lungs and introducing an oxygen-rich fluid, such as a perfluorocarbon — a compound capable of carrying exceptionally high levels of dissolved oxygen — directly into the intestines.

Research shows that this oxygen can move across the intestinal wall into the bloodstream, temporarily supporting oxygen levels while the lungs recover or other treatments take effect. The primary obstacle is the efficient clearance of carbon dioxide (CO2). However, early results from animal studies using newer techniques show a promising, albeit small, amount of CO2 removal via the colon, an effect that is now under further investigation.

Enteral ventilation research looks promising

So far, researchers have tested enteral ventilation on animals, including mice and pigs, with impressive results. In a 2021 study, animals suffering from low oxygen levels survived longer once scientists introduced oxygenated liquid into their intestines. Their blood oxygen levels rose, showing that the gut could indeed act as a secondary respiratory organ.

In Japan, researchers have taken the next step with a small human safety trial. Twenty-seven healthy volunteers received a non-oxygenated version of the perfluorocarbon liquid rectally. While this early test did not involve delivering oxygen, it proved subjects tolerated the process without serious side effects, reporting only mild bloating and discomfort. The next phase will test how effectively the intestines can actually absorb oxygen in humans.

Although still in the experimental stage, the technique could one day help patients in critical respiratory failure or serve as a backup in places where ventilators or ECMO machines aren’t available.

Researchers caution, however, that much more testing is needed to confirm its safety, measure how effectively the intestines can absorb oxygen, and address how to remove carbon dioxide, which still must be exhaled through the lungs.