Can someone with real medical competence tell me why this weird idea wouldn't work?

This idea occurred to me a couple of years ago. It concerns the need for patients with lung damage, or fluid-filled lungs -- such as pneumonia patients or victims of smoke inhalation -- to maintain blood oxygenation, when the normal process of O2 absorption from their lungs is frustrated. I suppose someone, at some point, might have tried using a heart-lung machine to bypass the lungs in desperate cases, but I don't know for sure. With heart-lung machines being more complicated, more expensive, and less common than ventilators anyway, this wouldn't seem to be much help in the COVID crisis, so something simpler is needed. Unfortunately, I'm not a doctor, nor any sort of medical expert, myself, and I don't know who I could recommend this idea to for possible evaluation.

The idea comes from one very odd observation. Some turtles -- air-breathing animals which totally lack gills -- are able to survive hibernation underwater for months at a time. Of course, this is partly due to a drastic slowing of the animals' metabolism, a common ability among reptiles, but it's not enough by itself. Recently, investigators learned that these turtles are actually capable of "breathing" underwater -- through their butts. Now, technically, it involves the cloaca, an organ found in reptiles and birds, but not humans. Now, I realize turtles are not humans, and (with one prominent exception) humans are not turtles, and a human intestine is not the same as a cloaca. But consider what the intestines do -- they absorb nutrients, water, and salts from the contents of the digestive tract (water and salts apparently flowing both ways, as needed), at least partly by simple diffusion. To make this process rapid enough to be effective, the inner surfaces of the intestines are covered with tiny protrusions called villi, which increase the surface area available for diffusion, complementary to the way the airways of the lungs are ramified into many tiny alveoli for rapid diffusion of O2 and CO2. So couldn't an intestine serve as an alternative lung ? This is an idea which could be quickly be tested on dogs or pigs -- use a colonoscope or similar device to insert a tube deep into the colon, pass in O2-enriched air and allow it to pass out again through the anus. Then cut the animal's O2 supply (substitute pure N2, e.g.) and monitor the blood oxygen level. Even if this method is not as effective as normal breathing, it could still be very useful. It probably couldn't substitute completely for a ventilator, but might substantially augment oxygenation for patients in extreme pulmonary distress -- maybe enough to tip the balance. The equipment involved is not much more complicated than the high-flow nasal cannulas commonly in use, and much simpler than a ventilator. When ventilators run out, maybe it could even serve as a stopgap until a ventilator becomes available.

Again, I'm not a doctor, and don't have any in the family or my circle of acquaintances to discuss this with, but I'm just putting this out there to see if anyone can find merit in it, or improve the idea to the point it's more worth considering. Hope it helps someone, somewhere, somewhen.




(Possible later development -- use silicone or fluorocarbon fluids -- artificial blood -- in place of air. Might be of interest for deep-sea diving, or at least SF stories about same.)