To begin with, the study authors removed the thin layer of mucus lining the gut of mice, in order to allow for enhanced diffusion of oxygen through epithelial cells. They then placed the rodents in a low-oxygen environment, which caused all of the animals to die within 11 minutes. However, when the researchers delivered oxygen gas directly into the anus of mice, three-quarters of the animals were able to survive inside the chamber for 50 minutes. Repeating the experiment on mice that had not had their gut mucosal layer removed, the authors noted a significantly smaller improvement in survival rates, with rodents remaining alive for an average of 18 minutes. While this finding indicates that mice are able to avoid respiratory failure by breathing through their buttholes, the need to remove gut mucosa makes this technique unsuitable for humans. The researchers decided to investigate an alternative method involving the administration of oxygenated liquid via the rectum.