While we often consider the butt as the exit for waste in our body, it is also an entryway with lifesaving potential. After all, humans and plenty of other mammals can absorb medications rectally. That\u2019s because there\u2019s a lot of blood vessels<\/a> in the area, allowing medicine easy entry. <\/p>\n\n\n\n But medicine is specially designed to maximize absorption in the body. Oxygen doesn\u2019t have nearly as easy a path towards entry into the bloodstream through the rectum because of the mucus membrane mammals have on the intestines. There are also important anatomical differences between our intestines and those of fish that already harness this ability. Animals that can breathe through their butts, like loaches<\/a>, had a much thinner epithelium in their guts and a lot less mucus. During the course of early development, a butt-breathing genetic pathway is turned on that helps dictate the structure of the intestine. When it\u2019s all said and done, the posterior end of the intestine is equipped with all the structures necessary for respiration (and gas exchange).<\/p>\n\n\n\n Would this mucus prevent oxygenation in mice? In the first experiment, researchers used a model of oxygen deprivation in mice, preventing them from breathing through their lungs. The control group didn\u2019t receive any intestinal ventilation, one group received oxygen through an anal catheter, and the final group had the mucus layer on their intestines \u201cscrubbed\u201d before receiving anal ventilation.https:\/\/cdn.iframe.ly\/api\/iframe?url=https%3A%2F%2Fmassivesci.com%2Farticles%2Fbutts-shape-big-anthropologist-evolution-how-why-explainer%2F&key=a91f6c63822d2172297a7435cae7a9eb&v=1&app=1<\/p>\n\n\n\n Remarkably, the mice supplied oxygen through their anus had elevated oxygen levels in their blood. The final group that also had their intestinal mucus scrubbed fared even better, surviving the longest in the low-oxygen conditions \u2014 five times as long as the control group. This experiment proved that there is potential for mammals to breathe through their butt, however, the mucus layer covering the intestinal epithelial cells makes it more difficult.<\/p>\n\n\n\n In a clinical setting, scrubbing the mucus off of a person\u2019s intestines isn\u2019t really feasible, and doesn\u2019t sound like a pleasant experience. But using a method akin to an enema may work, by infusing safe, oxygenated liquid through the butt. This liquid, called perfluorodecalin, could safely store and deliver oxygen via an enema. Due to the properties of this liquid, it doesn\u2019t need to scrub the mucus off of the intestines, meaning less discomfort and abrasion. Oxygen diffuses into the bloodstream while carbon dioxide diffuses out. Since it holds a lot of oxygen and carbon dioxide very easily, it is also delivered safely to the lungs<\/a>, and is already in clinical use. <\/p>\n\n\n\n In their next experiment, mice were placed in chambers with only 10 percent oxygen. While this isn\u2019t lethal, it is enough to induce the physiological effects of a lack of oxygen, hypoxia. The mice that received oxygen-loaded PFD rectally normalized their oxygenation back to normal levels. <\/p>\n\n\n\n In rats and pigs, the researchers repeated these experiments finding that two days of the protocol didn\u2019t lead to any significant adverse effects. Importantly, the diffusion and distribution of many different drugs are tested in pigs<\/a> due to similarities in physiology. While the authors couldn\u2019t figure out how exactly the oxygen passes into the intestine, they showed enough efficacy to permit more studies trials in animals and in humans. According to the press release<\/a>, the research team is working with Japan Agency for Medical Research and Development to conduct more experiments and potentially head to a human trial. This could increase the ventilation capacity of hospitals during future outbreaks of respiratory diseases.<\/p>\n\n\n\n During COVID-19, many hospitals find themselves short on ventilators<\/a>. During the pandemic, many will require the use of a ventilator for an average of 15 days<\/a>, while a few people will need significantly more time. Ventilators aren\u2019t something that a person can use for one day and then get discharged. The first wave of people requiring ventilators will receive them immediately. However, someone whose lungs fail the next day may need to survive for two weeks without one.<\/p>\n\n\n\nCan Rectal Ventilation Mitigate a Ventilator Shortage?<\/h3>\n\n\n\n