Suspended animation (stasis) Hydrogen sulfide takes the place of oxygen

Scientists are starting to understand that death isn't caused by oxygen deprivation itself, but by a chain of damaging chemical reactions that are triggered by sharply dropping oxygen levels. The thing is, those reactions require the presence of some oxygen. Hydrogen sulfide takes the place of oxygen, preventing those reactions from taking place. No chain reaction, no cell death. The patient lives.
Scientists hope work with poison gas can be a lifesaver -