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Patients must be stored in cold temperature to halt all chemical activity and fluid movement.  Storage has historically been in liquid nitrogen (LN2) at -196°C.  Storage can also be in a cryogenic freezer at -130°C.  This is not as extreme as the -196°C of liquid nitrogen (LN2), so it's known as Intermediate Temperature Storage (ITS). 

 

There's not yet a strong case to be made for using ITS. The warmer temperature might help minimize internal stress and avoid possible cracks.  The cost seems to be similar to traditional LN2.

 

Immersion in LN2 introduces some stress and may cause cracks, fractures, or pulverization of brain tissue.  A fracture is a complete separation into two parts, whereas a crack is only a partial propagation and an incomplete separation.  Neither of these would be a cause for concern, as very little molecular information would be lost and the original state could be easily inferred.  But fractures and cracks could be more complex and could involve some pulverization, which would transform some of the tissue into a powdered state with little information about the original structure.  It's unclear how much cracking actually takes place during current cryonics cases, but evidence suggests that there is probably some cracking.

 

ITS is one possible way to avoid cracks and improve storage quality, but the improvement is only theoretical.  We have explored ITS technology.  We have a cryogenic freezer with a built-in controller that injects LN2 gas once or twice a day to thermostatically maintain a desired set temperature.  The tissue would be stored in nitrogen gas rather than in liquid nitrogen. 

 

On Alcor's ITS page, they explain their current storage system.  They have informally and quietly offered ITS to a few people over the years, and they now have about six ITS patients.  Alcor's approach to ITS has been tentative and cautious for a number of good reasons.  In their case, it adds considerable cost for questionable benefit.  But Alcor's ITS is also different from ours.  They do not stabilize the tissue first with glutaraldehyde, nor do they validate CPA concentration with CT scanning prior to cooling.  Because the tissue is not stabilized, a warming event at Alcor would cause catastrophic damage and be completely unacceptable.  To eliminate this risk, their ITS storage costs must be much higher so that a typical failure would result in cooling rather than warming. 

 

ITS at Oregon Cryonics would not face these same limitations.  Our glutaraldehyde stabilization means that a warming event would probably be harmless. But the complex freezer is prone to occasional failure, and there are still many cases where LN2 must still be used instead of ITS.  Any case where any portion of the tissue has already been straight frozen could not be eligible for ITS.  Overall, we do not see an advantage to offering ITS.