IIRC during covid they did experiment with liquid oxygen exchange through the intestinal wall for patients whose lungs were so wrecked normal ventilators weren’t sufficient. So you could maybe engage in some anal breathing if you were to get a super-oxygenated fluid enema, but its not something the unassisted human body can do. Or tries to do, for that matter.
If you’re a turtle or a sea cucumber maybe.
IIRC during covid they did experiment with liquid oxygen exchange through the intestinal wall for patients whose lungs were so wrecked normal ventilators weren’t sufficient. So you could maybe engage in some anal breathing if you were to get a super-oxygenated fluid enema, but its not something the unassisted human body can do. Or tries to do, for that matter.