"The air we breathe is 21 percent oxygen. At 5 percent, (...) fish and flies — like us — would be dead in a few minutes. At 0.1 percent, it [is] another story. "You get a state of suspended animation and the creatures do not pass away, and that's the basis of what we see as an alternative way to think about critical care medicine," Roth says. "What you want to do is to have the patient's time slowed down, while everyone around them [like doctors] move at what we would call real time. (...) While it's true we need oxygen to live, it's also a toxin. (...) 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."