Artificial ventilation is an invasive procedure that can cause damage to the lungs and requires a lot of personnel. Japanese researchers suggest administering oxygen through the anus as a simple enema. It is proving to be a very effective and safe technique.
As with Covid-19, many pathologies lead to respiratory insufficiency requiring ventilation. This is done via an intubation tube that delivers oxygen to the lungs. The problem is that this invasive procedure itself can cause damage to the lungs, not to mention the risk of infection from bacteria from the mouth and the inability to eat.
Ryo Okabe and his colleagues at Tokyo Medical and Dental University (TMDU) have found another way: delivering oxygen through the anus. In fact, some animals, such as loaches, turtles, and sea cucumbers, have developed an alternative way of breathing when oxygen availability is limited: they take in air through the anus, which then distributes the oxygen through the intestinal wall into the body.
A technique inspired by suppositories
“The rectum has a very intricate network of blood vessels just below the mucosal surface, so drugs administered through the anus are easily absorbed into the bloodstream,” Ryo Okabe explains. This is the principle behind suppositories, so we wondered if oxygen could be administered in the same way.
The researchers initially thought of administering oxygen in gaseous form into the rectum. But although the procedure works in mice, it requires “rubbing” the rectal wall to increase blood flow and promote gas exchange. One can imagine that this must not be very pleasant. Ryo Okabe then developed a different method, diffusing perfluorodecalin with oxygen through the rectum, a fluid that can carry large amounts of oxygen and carbon dioxide similar to that used in premature infants. They placed animal guinea pigs (mice, pigs, and rats) under hypoxia and then applied their treatment.
No side effects
The animals no longer had respiratory problems and blood oxygenation was improved. “Interestingly, rectal ventilation required two to three times less fluid than if through the lungs,” the authors also wrote in their study, published in the journal Med. The researchers also said the small amount of fluid absorbed with the oxygen caused no adverse effects and did not disrupt gut bacteria, suggesting the method is safe.
Requires less medical personnel and equipment
“This is an idea that may seem provocative but should be taken very seriously,” judged Caleb Kelly of Yale University School of Medicine in a commentary accompanying the study. For example, this method, which resembles a simple enema, could greatly facilitate recovery in patients with respiratory failure or replace oxygenation with extracorporeal membrane oxygenation (EMCO), which is used primarily in severe cases of covid. It would also require fewer medical staff and less expensive equipment. This would have been very useful in the ICUs in recent months.