Cryopreservation begins the moment legal death is pronounced. The goal at every step is to preserve the fine structure of the brain as faithfully as possible.
- Stabilization. The patient is cooled and circulation and oxygenation are restored mechanically to slow the chemical changes that follow cardiac arrest.
- Cryoprotection. The blood is gradually replaced with a cryoprotectant solution. This acts like a medical antifreeze and is what makes vitrification possible.
- Cooling to storage temperature. The patient is slowly cooled to around minus 196 degrees Celsius, the temperature of liquid nitrogen, where all chemical activity effectively stops.
The key concept is vitrification rather than freezing, which avoids the ice damage that plain freezing would cause.