Why is cryopreservation sometimes attempted hours after clinical death?
Cryonics procedures are ideally begun by restoring circulation and breathing within moments of cardiac arrest. If this should not be possible, most people who choose cryonics choose to proceed with cryopreservation anyway. This is scientifically justified by the generally good appearance of brain tissue in electron micrographs during the early hours of clinical death. Much of what is known about neurodegenerative diseases is actually based on histochemical studies of brains obtained hours after clinical death, so clearly much chemical information still exists. Living neurons can sometimes be cultured as long as 4 hours, or even 8 hours after clinical death. Further discussion and references concerning post-mortem brain changes are available within this article, and also this one. These data suggest that the early stages of what we consider death today may actually be a treatable injury. This is not because death is reversible, but because what we think of as death today might not reall
