Hold onto your butts because this is a pretty weird one; have you ever heard of rectal ventilation? Until recently, no one really had or would even think of putting those words together. Thanks to the pandemic, the topic of ventilation has become a household concern. As the Delta variant continues to spread, ICU beds are filling up and there aren’t enough ventilators to go around. Researchers in Japan have come up with a solution and it’s called enteral ventilation via anus, aka EVA. Basically, it’s a procedure that increases blood oxygen levels through the intestinal tract. It may sound bizarre but the technique has been so successful that the next step is human trials. In case the world wasn’t weird enough for you, here are the details about this new treatment.

Enteral ventilation via anus aka EVA

enteral ventilation via anus

Image Courtesy of the Asahi Shimbun

Enteral ventilation via anus is a new procedure created by the Tokyo Medical and Dental University. The procedure is similar to an enema and works to deliver oxygen to the body through the distal gut. This medical procedure is groundbreaking, especially in cases where lung tissue damage is preventing air exchange. It does not mean that the future is everyone breathing through our butts. However, when someone is struggling to breathe, it means that we have another way of getting oxygen in their system. Combined with pulmonary ventilation, this new method could save a lot of lives.

How did they come up with butt breathing?

The inspiration behind the treatment came from watching the animal kingdom and looking at drug absorption methods. Researchers observed and studied animals that absorb oxygen through the intestines, paying special attention to the creatures that only do this during emergencies. Catfish, sea cucumbers, and orb-weaving spiders can absorb oxygen through their gut during survival situations. 

butt breathing

Image Courtesy of the Australian Museum

Ryo Okabe is one of the researchers that created and studied the procedure; he explains how the idea behind this new method came to the group. “The rectum has a mesh of fine blood vessels just beneath the surface of its lining, which means that drugs administered through the anus are readily absorbed into the bloodstream. This made us wonder whether oxygen could also be delivered into the bloodstream in the same way.”

How enteral ventilation via anus works – Gas or Liquid

Basically, there are two options to increase oxygen through enteral ventilation: using oxygen in either a liquid or gas form. Both options work but gas is more invasive than liquid. To absorb oxygen in a gas form, the rectum needs to be rubbed and inflamed to increase circulation. As this would be too uncomfortable, the researchers used oxygenated perfluorodecalin (PFD), a safe liquid that carries large amounts of oxygen and carbon dioxide. Tests were carried out on animals and found to be extremely successful. 

How enteral ventilation via anus works - Gas or Liquid

According to researcher Ryo Okabe, “We used experimental models of respiratory failure in mice, pigs, and rats to try out two methods: delivering oxygen into the rectum in gas form, and infusing an oxygen-rich liquid via the same route.”

Can’t argue with the results

The results of the testing for this procedure were pretty incredible. After undergoing enteral ventilation via anus, blood oxygen levels increased and behavior normalized. Through the use of cellular staining, researchers confirmed that oxygenation improved within cells all over the body. On top of that, there were minimal amounts of PFD residuals absorbed with the liquid oxygen, and gut bacteria was undisturbed. 

Takanori Takebe, another researcher and co-author of this study had this to say on the subject. “Patients in respiratory distress can have their oxygen supply supported by this method to reduce the negative effects of oxygen deprivation while the underlying condition is being treated. Enteral ventilation showed great promise in our asphyxia-like experimental model. The next steps will be to test safety of the EVA approach with more profound mechanistic understanding by which it works, and to establish effectiveness in humans in a clinical setting.”

Footnote(s)

https://doi.org/10.1016/j.medj.2021.04.004
https://www.asahi.com/ajw/articles/14350603